CA1118547A - Hot melting adhesive comprising a fluoroelastomer, an ethylene copolymer and a tackifier - Google Patents
Hot melting adhesive comprising a fluoroelastomer, an ethylene copolymer and a tackifierInfo
- Publication number
- CA1118547A CA1118547A CA000322548A CA322548A CA1118547A CA 1118547 A CA1118547 A CA 1118547A CA 000322548 A CA000322548 A CA 000322548A CA 322548 A CA322548 A CA 322548A CA 1118547 A CA1118547 A CA 1118547A
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- Prior art keywords
- hot melt
- melt adhesive
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Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
- C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
- C09J123/04—Homopolymers or copolymers of ethene
- C09J123/08—Copolymers of ethene
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J127/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Adhesives based on derivatives of such polymers
- C09J127/02—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
- C09J127/12—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Adhesives based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/20—Adhesives in the form of films or foils characterised by their carriers
- C09J7/22—Plastics; Metallised plastics
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
- C09J7/35—Heat-activated
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
- C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
- C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
Abstract
ABSTRACT
Novel hot melt adhesives comprise a fluoroelastomer an ethylene copolymer and a tackifier. Preferably the adhesive contains 20 to 40% by weight of the fluorocarbon elastomer, 40 to 60% by weight of the ethylene copolymer and 10 to 30% by weight of the tackifier. The adhesives will bond well to a wide variety of substrates, including substrates of low surface energy such as partially fluorinated polymers, even after prolonged exposure to high temperatures.
Novel hot melt adhesives comprise a fluoroelastomer an ethylene copolymer and a tackifier. Preferably the adhesive contains 20 to 40% by weight of the fluorocarbon elastomer, 40 to 60% by weight of the ethylene copolymer and 10 to 30% by weight of the tackifier. The adhesives will bond well to a wide variety of substrates, including substrates of low surface energy such as partially fluorinated polymers, even after prolonged exposure to high temperatures.
Description
ill8S47 This invention relates to hot melt adhesives and to their use for bonding substrates together, especially substrates having low surface energies.
Hot melt adhesives (also known as thermoplastic adhesives) are well known in the art and have valuable advantages in processing, storage and application. However, many of the known hot-melt adhesives will not bond well to materials having low critical surface energies, in particular fluorinated polymers, and/or are unstable (i.e.
they melt and flow ar.d/or are chemically unstable) at the elevated temperatures (e.g. above 100C, especially above 130C) at which the use of such materials is often particularly valuable.
We have now discovered a novel hot melt adhesive which will bond well to a wide variety of substrates (including a number of substrates for which known hot melt adhesives are unsatisfactory) even after prolonged exposure to elevated temperatures.
In its first aspect, the invention provides a hot melt adhesive composition which comprises (1) an ethylene copolymer containing polar groups;
Hot melt adhesives (also known as thermoplastic adhesives) are well known in the art and have valuable advantages in processing, storage and application. However, many of the known hot-melt adhesives will not bond well to materials having low critical surface energies, in particular fluorinated polymers, and/or are unstable (i.e.
they melt and flow ar.d/or are chemically unstable) at the elevated temperatures (e.g. above 100C, especially above 130C) at which the use of such materials is often particularly valuable.
We have now discovered a novel hot melt adhesive which will bond well to a wide variety of substrates (including a number of substrates for which known hot melt adhesives are unsatisfactory) even after prolonged exposure to elevated temperatures.
In its first aspect, the invention provides a hot melt adhesive composition which comprises (1) an ethylene copolymer containing polar groups;
(2) a fluorocarbon elastomer; and
(3) a tackifier.
In its second aspect, the invention provides a bonded assembly comprising two substrates which are bonded together through a layer of a hot melt adhesive as defined above.
5~
In its third aspect the invention provides a process for making a bonded assembly which comprises pressing two substrates against a layer of a hot melt adhesive as defined above, which layer lies between the substrates and is at a temperature above its activation temperature, and maintaining pressure between the substrates while the hot melt adhesive cools to below its activation temperature.
Generally the hot melt adhesive will be placed bet~een the substrates while it is solid, either as a self-supporting preform of any desired shape or as a layer adherent to one of the substrates, and the assembly will then be heated, while pressing the substrates towards each other, to heat the hot melt adhesive above its activation temperature.
The excellent bonding powers of the novel hot melt adhesives are most surprising in view of the fact that the fluoroelastomers alone are poor adhesives and the fact that known hot melt adhesives based on EVA/tackifier mixtures will not provide satisfactory bonds to low surface energy substrates, and are unstable at elevated temperatures.
The percentages of the ethylene copolymer (1), the fluoroelastomer (2) and the tackifier (3) which are generally, preferably, and most preferably used, are as set out below, the percentages being by weight based on the total weight of the three specified components.
EthyleneEluoroelastomer Tackifier Copolymer(l)(2) (3) Generally used 10-90%5-60% 5-40%
Preferably used 30-80%10-50% 5-40%
Most preferably used 40-60% 20-40~ 10-30%
~`- 1118S47 The ethylene copolymer (1) is preferably a crystalline copolymer containing at least 50 mole %, preferably at least 60 mole %, especially at least 65 mole %
of units derived from ethylene, and at least 5 mole %, preferably 10 to 40 mole %, especially 15 to 35 mole %, particularly 15 to 25 mole %, of units which contain at least one polar group, which units may be obtained by copolymerising at least one unsaturated comonomer containing at least one polar group and/or by modification, e.g. by partial or complete hydrolysis, of units derived from at least one such comonomer. The comononomer preferably contains a terminal ethylenic double bond. Preferred polar groups are carboxyl groups and carboxylic ester groups, including both pendant carboxylic ester groups, derived for example from alkyl esters of unsaturated carboxylic acids, and pendant alkyl carbonyloxy groups, derived for example from vinyl esters of saturated carboxylic acids. Preferably at least some of the polar groups are acid groups. Other polar groups include cyano groups and hydroxyl groups, which may be obtained for example by hydrolysis of copolymers containing units derived from vinyl esters. Particularly suitable monomers include vinyl esters of saturated carboxylic acids containing 1 to 4 carbon atoms, especially vinyl acetate; acrylic and methacrylic acids; and alkyl (including cycloalkyl) and aryl esters, especially methyl esters, of acrylic and methacrylic acids, said esters preferably containing at most 10 carbon atoms, especially methyl methacrylate, methyl acrylate and ethyl acrylate.
The copolymer may contain units in addition to those derived from ethylene and those containing polar groups, but the amount of such additional units is preferably less than 20 mole %, particularly less 10 mole %, especially substantially zero.
Particularly preferred as the copolymer (1) is a copolymer of ethylene and vinyl acetate and 0 to 10 mole %
of another comonomer, preferably a polar comonomer. Such copolymers are referred to herein as EVA copolymers. The vinyl acetate content in such copolymers is preferably 20 to 30 mole %. For some purposes an EVA copolymer having a melt index of not more than lO, eg. 1.5 to 7.51 is preferred, with melt indexes greater than 4, especially greater than 5, often being especially preferred. It is also often preferred that the EVA copolymer have a tensile strength of at least 2000 psi (140 kg/cm ).
Suitable commercially available ethylene copolymers include the copolymers of ethylene and ethyl acrylate with a small proportion of methacrylic acid which B are sold by Union Carbide as DPD 6169 and DPD~6~81, and the 72 : 28 copolymers of ethylene and vinyl acetate which are sold by du Pont as Elvax 4260 and 260.
The fluorocarbon elastomer (2) is preferably a polymer of one or more fluorinated monomers containing ethylenic unsaturation and optionally one or more other compounds containing ethylenic unsaturation. The fluorinated monomer may be a perfluorinated monoolefin, for example hexafluoropropylene or tetrafluoroethylene, or a partially 1uorinated monoolefin which may contain other substituents, eg. chlorine or perfluoroalkoxy, for example vinylidene fluoride, chlorotrifluoroethylene and perfluoroalkyl vinyl ethers in which the alkyl group contains up to six carbon atoms, eg. perfluoro (methyl vinyl ether); the mono-olefin is preferably a straight or branched chain compound having a terminal ethylenic double bond and containing less than six carbon atoms, especially two or tra~ ~ rh~ ~
11~854~
three carbon atoms. The elastomer preferably consists of units derived from fluorine-containing monomers. When units derived from other monomers are present, the amount thereof is preferably less than 30 mole %, generally less than 15 mole %; such other monomers include, for example, olefins containing less than six carbon atoms and having a terminal ethylenic double bond, especially ethylene and propylene.
The elastomer will preferably consist of carbon, hydrogen, fluorine and oxygen atoms.
Preferred elastomers are coplymers of vinylidene fluoride and at least one other fluorinated monomer, especially one or more of hexafluoropropylene, tetrafluoroethylene and chlorotrifluoroethylene, the vinylidene fluoride content preferably being 30 to 70 mole . Commercially available fluoroelastomers of this class include copolymers of vinylidene fluoride and B hexafluoropropylene such as Viton~ A, Viton~A35 and Vito ~AHV
sold by du Pont; copolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene such as Viton B
and Viton BS0 sold by du Pont; and copolymers of vinylidene fluoride and chlorotrifluoroethylene such as Kel-F~sold by Minnesota Mining and Manufacturing Co. The Mooney viscosity of the elastomer at 100C is generally 20 to 200, preferably 30 to 160.
.
The term ~tackifier" is used in adhesive art to denote a material which when added to an adhesive composition promotes its adhesion to a substrate, by increasing its ability to wet the substrate. Many tackifiers are known. We prefer to use low molecular weight polymers of monomers which contain ethylenic unsaturation and are free of polar groups, for example polymers of one or ~ t~
`" 1118~;~7 more compounds of the formula Rl, CH = CR2 R3 wherein each of Rl, R2 and R3, which may be the same or different, is a substituted or unsubstituted alkyl (including cycloalkyl), alkenyl (including cycloalkenyl), aryl, aralkyl or alkaryl radical containing less than ten r ~ ~
carbon atoms. Suitable such tackifiers include Nevpene7r 9500, which is believed to be a copolymer of a mixture of aromatically and alphatically substituted ethylenes, and Piccotex~ 5, which is believed to be a copolymer of vinyl toluene and ~ -methylstyrene. Other tackifiers which can be used include terpene-phenolic resins (eg. Nevillac Hard).
The tackifiers used preferably have at least one of the following properties Brookfield Viscosity at 160 80-1500 centipoises Ball-and-Ring Softening point 50-130 C
Molecular Weight <3000 As previously indicated, the adhesives of the present invention will bond to a wide variety of substrates, including a number of substrates, especially the fluoropolymers described below, to which many known hot melt adhesives provide bonds which are greatly inferior, especially after exposure to elevated temperatures. Thus adhesives of the present invention will bond well to materials having critical surface energies above 30 dynes/cm, and even to materials which have lower surface energies, for example as low as 25 dynes/cm, and which are fluoropolymers containing at most 65% by weight of fluorine.
Suitable substrates include many organic polymers, for example polyarylenes, eg. "Stilan'', polyamides, eg. nylons, polyimides, eg. "Kapton", polyamide-imides, eg. "Torlon'~
polyethylene and other polyolefins, polyphenylene sulphide, eg. "Ryton", and metals, for example aluminum and copper. The ~ t~d~e r~r~k adhesives are especially useful for bonding fluoro polymers which are homopolymers of partially fluorinated olefins, copolymers of at least one partially fluorinated or perfluorinated olefin and at least one olefin, and copolymers of at least one partially fluorinated olefin and at least one perfluorinated olefin, which fluoropolymers may contain O to 15 mole % of units derived from other comonomers, particularly polyvinylidene fluoride (eg.
B "Kynar"), ethylene/tetrafluorethylene copolymers (eg.
"Tefzel*) and ethylene/chlorotrifluoroethylene copolymers (èg.~nHalar~). The materials which are bonded together can of course be the same or different, and one or both of them can be a polymer which has been cross-linked, eg. by irradiation. One or both of the substrates to be bonded together can be heat-recoverable; for example a heat-shrinkable sleeve or cap can be provided with a coating of the adhesive, to provide an article which can be shrunk onto a substrate while simultaneously or subsequently activating the adhesive. Thé
adhesives of the invention are particularly useful for bonding together insulating components of electrical systems, for example the insulating jacket of a flat cable to the body portion of a connector for the cable.
In addition to the above-mentioned three basic components, the adhesive may contain additives designed to improve specific aspects of its performance, such as thermooxidative stability and stiffness. Thus, for example, antioxidants such as butylated hydroxytoluene (BHT), Santowhite (4~4'-thiObiS(6-t-butyl-m-cresol)~ Irganox~ 093 (an organic antioxidant manufactured by Geigy), and Ferroan (an oligomeric phenolic antioxidant manufactured by Raychem) may be used, either individually or in combination. The modulus of the adhesive can be increased with fillers such ~e ~
}5~7 as silica, glass fibers and glass bubbles. Reagents for crosslinking the fluoroelastomer and/or the ethylene copolymer, such as a peroxide or an alkaline earth metal oxide and a diamine or its derivative, eg. dicumyl peroxide or N,N'-m-phenylene dimaleimide, may be included in the adhesive so that when it is exposed to elevated temperatures, crosslinking will occur and the adhesive will acquire further strength both at room temperature and at higher temperatures. When such a cross-linking agent is used, the other ingredients are preferably ones which contain cross-linking sites. It will be apparent to those skilled in the art that these and other common additives such as pigments and stabilizers against ultra violet light may be used singly or in combination.
The ingredients of the adhesive can be mixed together by conventional mixing techniques, for example as described in the Examples be~low. However, it has surprisingly been found that by blending the ingredients at relatively low temperatures, eg. from 50 to 175C, preferably from 50 to 100C, the bond strength obtained under the same bonding conditions is often at least as good as when the ingredients are blended at temperatures above 175C. After the ingredients have been mixed, the mixture i8 preferably granulated (eg. under liquid nigrogen) so as to make it suitable for melt-extrusion. It is also possible to mix the ingredients and to extrude the mixture in a single operation, eg. by use of a twin-screw extruder.
The adhesive preferably has a softening point as determined by Thermomechanical Analysis (TMA), of 60 to 100C, preferably 65 to 90C. When, as is preferred, the adhecive is used as a preform (which may be in the form of a layer on one of the substrates) it is preferably shaped at a temperature which is at least 40C above its softening ~118547 point, but which, when the adhesive is in the form of a layer on one of the substrates, is not so high as to damage the substrate, generally below 250C, preferably 150 to 200C. The adhesive must be heated to its activation temperature before it will bond two substrates together, and it is preferably heated to a temperature of at least 150C, eg. 150 to 220C. Optimum bond strengths are often obtained at relatively high bonding temperatures, eg. 210 to 290C, but especially at temperatures above 220C care must be taken to avoid the formation of bubbles. The bonding temperature need be maintained for a relatively short time, eg. 10 to 30 seconds. The pressure between the substrates during the bonding process is generally S to 25 psi (0.35 to 1.75 kg/cm2), preferably not more than 20 psi (1.4 kg/cm2). When using substrates which are not too thick, it is convenient to subject an assembly of the substrates and the adhesive preform to heat and pressure by means of a press having heated platens.
The invention is illustrated by the following examples in which parts are by weight and temperatures are in degrees Centigrade, except where stated otherwise.
In each of the Examples the adhesive was prepared in a Brabender Plasti-corder. The mixing chamber was preheated to 210, and the fluoroelastomer was introduced, followed by the ethylene copolymer one minute later and the tackifier portionwise four minutes later. Throughout the blending process the temperature was maintained at 210 and the speed of the mixing screws at 25-45 rpm. When the mixture had been rendered homogeneous it was removed and pressed into slabs 10 mil (0.0025 cm) thick in a press having platens coated with poly(tetrafluoroethylene), the pressing being for 30 seconds at 200C and 15,000 psi (1050 kg/cm2).
Test specimens 3 x 1 inch (7.5 x 2.5 cm) were cut from the slabs and bonded to specimens of the various substrates by placing the adhesive test specimen in contact with the substrate for 10 to 50 seconds at 200 to 250 under a pressure of about 20 psi (1.4 kg/cm2). After heat aging in a dry air circulating oven as specified, the adhesive strength was measured either as a 90 or 180 peel value at a peel rate of 10 inches/minute (25 cm/minute) with an Instron tester.
The various ingredients of the adhesives which are identified by their trade names in the Examples below are believed to be materials as further identified below DPD-6169 A copolymer of ethylene and ethyl/acrylate (molar ratio 82:18) having a Melt Index of about 6 Viton A35 A copolymer of vinylidene fluoride and hexafluoropropylene (molar ratio 60:40) having a Mooney viscosity at 100 C of 35 + 5) Piccotex 75 A copolymer of vinyl toluene and O~-methyl styrene having a melting point of about 75C.
Elvax 4260 A copolymer of ethylene, methacrylic acid and vinyl acetate (28 mole %) having a Melt Index of about 6.
Elvax 265 A copolymer of ethylene and vinyl acetate (molar ratio 72:28) having a Melt Index of about 6.
Elvax 360 A copolymer of ethylene and vinyl acetate (molar ratio about 75:25) having a Melt Index of 1.6 to 2.4.
~1~8S47 Viton AHV A copolymer of vinylidene fluoride and hexfluoropropylene (molar ratio 60:40) having a Mooney Viscosity at 100 C of about 160.
The Kynar and Tefzel materials used as substrates in the tests of the adhesives had been cross-linked by irradiation, thus giving them sufficient stability for use in the heat-aging tests.
EXAMPLE I
An adhesive blend (hereafter referred to as Adhesive I) comprising 40 parts Viton A-35, 40 parts DPD 6169, and 20 parts Piccotex 75 was prepared. Its bonding properties to a variety of substrates after heat aging for up to 1000 hours at 150 are given in Table I. As can be seen, outstanding peel strength is retained even to the conclusion of the testO In fact, samples which have been exposed to some heat develop a bond that is stronger than the initial one.
EXAMPLE II
A mixture (designated Adhesive II) comprising 50 parts Elvax 4260, 30 parts Viton A35 and 20 parts Piccotex 75 was prepared and tested as in Example I. The results are given in Table II. Again, the outstanding bond strength after 1000 hours aging at 150 is apparent.
Similar but more viscous adhesives were prepared by using Elvax 265 or a mixture of Elvax 4260 (20 parts) and Elvax 360 (30 parts) in place of the Elvax 4260, and Viton AHV
in place of the Viton A35.
EXAMPLE III
Adhesive blends comprising Viton A35, DPD 6169 and Piccotex 75 were prepared. The tackifier concentration was 20% throughout, but the Viton and DPD 6169 concentrations were varied. Table III shows the effect of varying the Viton concentration on the strength of the bond formed between Tefzel and Kynar. The table shows that the addition of Viton helps adhesion and that maximum improvement occurs at about 30% Viton.
In the 90 peel tests used to evaluate these adhesives the elasticity of the adhesive plays an important role in determining bond strength. An elastic adhesive can deform at the peel junction, thus absorbing much of the stress that would otherwise be transmitted to the adhesive bond.
Thus, the Viton performs the dual function of rendering the adhesive elastically deformable and thermooxidatively stable.
EXAMPLE IV
Adhesive blends comprising Viton A35, DPD 6169, and Piccotex 75 were prepared in which the Viton to DPD 6169 ratio was kept constant while the Piccotex percentage was varied.
Table IV shows the effect of varying the tackifier concentration on the strength of the bond formed between Kynar and Tefzel surfaces, and demonstrates that optimal performance is achieved at a 20% loading of tackifier.
EXAMPLE V
Adhesive blends of 40-50% Elvax 4260, 20 to 30%
Viton A35 and 20% Piccotex 75 were filled with 5 to 20% glass fibers. The effect of varying the glass fiber loading on the mechanical properties of the blends and on the strength of the 111~35~7 bond formed between Stilan and Kynar materials is shown in Table V. Fiber reinforcement of the adhesives to give substantially stiffer material without sacrificing adhesion is possible, and is valuable for situations which require a more rigid adhesive than the unfilled blends.
EXAMPLE VI
To demonstrate the importance of a fluoroelastomer in rendering the adhesives more thermooxidatively stable, a blend of 80% DPD 6169 and 20% Piccotex 75 was prepared and used to bond Stilan to Kynar and Tefzel to Tefzel. The bonded assemblies were then heat aged at 150C. The results, provided in Table VI, show that the adhesives without Viton do not heat age as well. In addition to the numerical data of Table VI, visual inspection of the samples after aging shows that the adhesive is much more brittle than a comparable sample containing Viton.
EXAMPLE VII
Example VI was repeated except that a blend of 30%
Elvax 4260 and 20% Piccotex 75 was used. The results are given in Table VII.
-~--` 152/178 ~8547 Testing of Adhesive I
.Hrs Aged90 Peel Strength Mode of Substrates at 150 lb/in Width Failure SKynar-Tefzel 0 6 to 10 Adhesive-Tefzel " 100 21.1 . Adhesive-Kynar u .. 250 33.7 ,'~ixed " " S00 13.6 Adhesive-Kynar 750 19.5 0 u ~ 1000 22.6 " "
Kynar-Stilan 0 5.9 " 100 1.3 Adhesive-Stilan n 250 1.7 ,- ., u " 500 3.5 " "
" " 750 15.4 " "
" " 1000 10.9 " . "
Tefzel-Ryton 0 8b Adhesive-Tefzel 250 30b Mixed ~ u 500 35b Mixed 20Tefzel-Torlon 0 6b Adhesive-Tefzel 250 15b Mixed u u 500 28b Adhesive-Tefzel ' bl80 peet _ ---15--. . - - .
---~ 152/178 11185~7 TABEE II
: Testing of Adhes;ve II
Hrs Aged90 Peel Strength Mode of Substrates .at 150 lbtin Width Failure 5Tefzel-Kynar 0 6.6 Adhesive-Kynar : ~ " 100 26 " " 250 26 Mixed " " S00 28 "
~ 750 28 " " 1000 24 "
Kynar-Stilan 0 5.8 Adhesive-Stilan " " 100 10.3 " " -" " 250 10.4 " "
" " 500 12.7 " "
" " 750 11.5 " "
~ " 1000 11.7 Tefzel-Ryton 0 6.22 Adhesive-Tefzel " " 250 202 Mixet .
~' " " 500 262 "
20Tefzel-Torlon 0 5~62 Adhesive-Tefzel " " 250 8.62 Mixed " " 500 23.62 Adhesive-Tefzel 2 180 Peel :
-- ---- -15- 1 ~ l 1~85~7 .
- TABLE III
Effect of Yarying Viton Concentration on Bond Strength Percent Yiton A35 Bond Str~Q_h, lb/in 0 5.0 6.7 7~0 8.4 7.4 3.7 ABLE IY
Effect of Piccotex 75 Concentration on Bond Strength Percent Piccotex ?5 T-peel, lb/in 5.6 6.6 5.6 -The Effect of Glass Fibers on Adhesion 90 Peel Strength 20 X Glass Fibers Substrates lb/in (width) pliYoung's Modulus (psi) 0 Stilan-Kynar 5.1 350 " 6.1 1075 " 6.4 5444 n 5.4 5615 " 6.3 12042 .
., ~118547 Heat Aging of a Blend Comprising 80X DP0 6169 and 20~ Piccotex 75 90 Peel, SubstratesHrs at 150 lb/in Mode of Failure _ Stilan-Kynar 250 5.5 Mixed 500 1.9 Adhesive-Stilan 750 1.7 " "
1000 0.8 " "
Tefzel-Tefzel 0 10.0 Adhesive 100 16.6 "
250 11.7 Cohesive : 500 5.2 750 S.0 Adhesive ; 1000 4.5 :; ' ' TABLE VII
1 Heat Aging of a Blend Comprisin~ 80% Elvax 4260 and 20% Piccotex 75 90 Peel, Substratesa Hrs at 150 lb/in Mode of Failure Stilan-Stilan 0 2 Adhesive ~100 4.3 "
250 4.1 500 4.2 "
750 6.0 ~ 1000 5.2 - 25 Tefzel-Tefzel ll.S Adhesive 100 17.5 "
250 10.0 "
SoO 6.8 "
', 750 3.5 "
. .1000 4.Q . "
_
In its second aspect, the invention provides a bonded assembly comprising two substrates which are bonded together through a layer of a hot melt adhesive as defined above.
5~
In its third aspect the invention provides a process for making a bonded assembly which comprises pressing two substrates against a layer of a hot melt adhesive as defined above, which layer lies between the substrates and is at a temperature above its activation temperature, and maintaining pressure between the substrates while the hot melt adhesive cools to below its activation temperature.
Generally the hot melt adhesive will be placed bet~een the substrates while it is solid, either as a self-supporting preform of any desired shape or as a layer adherent to one of the substrates, and the assembly will then be heated, while pressing the substrates towards each other, to heat the hot melt adhesive above its activation temperature.
The excellent bonding powers of the novel hot melt adhesives are most surprising in view of the fact that the fluoroelastomers alone are poor adhesives and the fact that known hot melt adhesives based on EVA/tackifier mixtures will not provide satisfactory bonds to low surface energy substrates, and are unstable at elevated temperatures.
The percentages of the ethylene copolymer (1), the fluoroelastomer (2) and the tackifier (3) which are generally, preferably, and most preferably used, are as set out below, the percentages being by weight based on the total weight of the three specified components.
EthyleneEluoroelastomer Tackifier Copolymer(l)(2) (3) Generally used 10-90%5-60% 5-40%
Preferably used 30-80%10-50% 5-40%
Most preferably used 40-60% 20-40~ 10-30%
~`- 1118S47 The ethylene copolymer (1) is preferably a crystalline copolymer containing at least 50 mole %, preferably at least 60 mole %, especially at least 65 mole %
of units derived from ethylene, and at least 5 mole %, preferably 10 to 40 mole %, especially 15 to 35 mole %, particularly 15 to 25 mole %, of units which contain at least one polar group, which units may be obtained by copolymerising at least one unsaturated comonomer containing at least one polar group and/or by modification, e.g. by partial or complete hydrolysis, of units derived from at least one such comonomer. The comononomer preferably contains a terminal ethylenic double bond. Preferred polar groups are carboxyl groups and carboxylic ester groups, including both pendant carboxylic ester groups, derived for example from alkyl esters of unsaturated carboxylic acids, and pendant alkyl carbonyloxy groups, derived for example from vinyl esters of saturated carboxylic acids. Preferably at least some of the polar groups are acid groups. Other polar groups include cyano groups and hydroxyl groups, which may be obtained for example by hydrolysis of copolymers containing units derived from vinyl esters. Particularly suitable monomers include vinyl esters of saturated carboxylic acids containing 1 to 4 carbon atoms, especially vinyl acetate; acrylic and methacrylic acids; and alkyl (including cycloalkyl) and aryl esters, especially methyl esters, of acrylic and methacrylic acids, said esters preferably containing at most 10 carbon atoms, especially methyl methacrylate, methyl acrylate and ethyl acrylate.
The copolymer may contain units in addition to those derived from ethylene and those containing polar groups, but the amount of such additional units is preferably less than 20 mole %, particularly less 10 mole %, especially substantially zero.
Particularly preferred as the copolymer (1) is a copolymer of ethylene and vinyl acetate and 0 to 10 mole %
of another comonomer, preferably a polar comonomer. Such copolymers are referred to herein as EVA copolymers. The vinyl acetate content in such copolymers is preferably 20 to 30 mole %. For some purposes an EVA copolymer having a melt index of not more than lO, eg. 1.5 to 7.51 is preferred, with melt indexes greater than 4, especially greater than 5, often being especially preferred. It is also often preferred that the EVA copolymer have a tensile strength of at least 2000 psi (140 kg/cm ).
Suitable commercially available ethylene copolymers include the copolymers of ethylene and ethyl acrylate with a small proportion of methacrylic acid which B are sold by Union Carbide as DPD 6169 and DPD~6~81, and the 72 : 28 copolymers of ethylene and vinyl acetate which are sold by du Pont as Elvax 4260 and 260.
The fluorocarbon elastomer (2) is preferably a polymer of one or more fluorinated monomers containing ethylenic unsaturation and optionally one or more other compounds containing ethylenic unsaturation. The fluorinated monomer may be a perfluorinated monoolefin, for example hexafluoropropylene or tetrafluoroethylene, or a partially 1uorinated monoolefin which may contain other substituents, eg. chlorine or perfluoroalkoxy, for example vinylidene fluoride, chlorotrifluoroethylene and perfluoroalkyl vinyl ethers in which the alkyl group contains up to six carbon atoms, eg. perfluoro (methyl vinyl ether); the mono-olefin is preferably a straight or branched chain compound having a terminal ethylenic double bond and containing less than six carbon atoms, especially two or tra~ ~ rh~ ~
11~854~
three carbon atoms. The elastomer preferably consists of units derived from fluorine-containing monomers. When units derived from other monomers are present, the amount thereof is preferably less than 30 mole %, generally less than 15 mole %; such other monomers include, for example, olefins containing less than six carbon atoms and having a terminal ethylenic double bond, especially ethylene and propylene.
The elastomer will preferably consist of carbon, hydrogen, fluorine and oxygen atoms.
Preferred elastomers are coplymers of vinylidene fluoride and at least one other fluorinated monomer, especially one or more of hexafluoropropylene, tetrafluoroethylene and chlorotrifluoroethylene, the vinylidene fluoride content preferably being 30 to 70 mole . Commercially available fluoroelastomers of this class include copolymers of vinylidene fluoride and B hexafluoropropylene such as Viton~ A, Viton~A35 and Vito ~AHV
sold by du Pont; copolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene such as Viton B
and Viton BS0 sold by du Pont; and copolymers of vinylidene fluoride and chlorotrifluoroethylene such as Kel-F~sold by Minnesota Mining and Manufacturing Co. The Mooney viscosity of the elastomer at 100C is generally 20 to 200, preferably 30 to 160.
.
The term ~tackifier" is used in adhesive art to denote a material which when added to an adhesive composition promotes its adhesion to a substrate, by increasing its ability to wet the substrate. Many tackifiers are known. We prefer to use low molecular weight polymers of monomers which contain ethylenic unsaturation and are free of polar groups, for example polymers of one or ~ t~
`" 1118~;~7 more compounds of the formula Rl, CH = CR2 R3 wherein each of Rl, R2 and R3, which may be the same or different, is a substituted or unsubstituted alkyl (including cycloalkyl), alkenyl (including cycloalkenyl), aryl, aralkyl or alkaryl radical containing less than ten r ~ ~
carbon atoms. Suitable such tackifiers include Nevpene7r 9500, which is believed to be a copolymer of a mixture of aromatically and alphatically substituted ethylenes, and Piccotex~ 5, which is believed to be a copolymer of vinyl toluene and ~ -methylstyrene. Other tackifiers which can be used include terpene-phenolic resins (eg. Nevillac Hard).
The tackifiers used preferably have at least one of the following properties Brookfield Viscosity at 160 80-1500 centipoises Ball-and-Ring Softening point 50-130 C
Molecular Weight <3000 As previously indicated, the adhesives of the present invention will bond to a wide variety of substrates, including a number of substrates, especially the fluoropolymers described below, to which many known hot melt adhesives provide bonds which are greatly inferior, especially after exposure to elevated temperatures. Thus adhesives of the present invention will bond well to materials having critical surface energies above 30 dynes/cm, and even to materials which have lower surface energies, for example as low as 25 dynes/cm, and which are fluoropolymers containing at most 65% by weight of fluorine.
Suitable substrates include many organic polymers, for example polyarylenes, eg. "Stilan'', polyamides, eg. nylons, polyimides, eg. "Kapton", polyamide-imides, eg. "Torlon'~
polyethylene and other polyolefins, polyphenylene sulphide, eg. "Ryton", and metals, for example aluminum and copper. The ~ t~d~e r~r~k adhesives are especially useful for bonding fluoro polymers which are homopolymers of partially fluorinated olefins, copolymers of at least one partially fluorinated or perfluorinated olefin and at least one olefin, and copolymers of at least one partially fluorinated olefin and at least one perfluorinated olefin, which fluoropolymers may contain O to 15 mole % of units derived from other comonomers, particularly polyvinylidene fluoride (eg.
B "Kynar"), ethylene/tetrafluorethylene copolymers (eg.
"Tefzel*) and ethylene/chlorotrifluoroethylene copolymers (èg.~nHalar~). The materials which are bonded together can of course be the same or different, and one or both of them can be a polymer which has been cross-linked, eg. by irradiation. One or both of the substrates to be bonded together can be heat-recoverable; for example a heat-shrinkable sleeve or cap can be provided with a coating of the adhesive, to provide an article which can be shrunk onto a substrate while simultaneously or subsequently activating the adhesive. Thé
adhesives of the invention are particularly useful for bonding together insulating components of electrical systems, for example the insulating jacket of a flat cable to the body portion of a connector for the cable.
In addition to the above-mentioned three basic components, the adhesive may contain additives designed to improve specific aspects of its performance, such as thermooxidative stability and stiffness. Thus, for example, antioxidants such as butylated hydroxytoluene (BHT), Santowhite (4~4'-thiObiS(6-t-butyl-m-cresol)~ Irganox~ 093 (an organic antioxidant manufactured by Geigy), and Ferroan (an oligomeric phenolic antioxidant manufactured by Raychem) may be used, either individually or in combination. The modulus of the adhesive can be increased with fillers such ~e ~
}5~7 as silica, glass fibers and glass bubbles. Reagents for crosslinking the fluoroelastomer and/or the ethylene copolymer, such as a peroxide or an alkaline earth metal oxide and a diamine or its derivative, eg. dicumyl peroxide or N,N'-m-phenylene dimaleimide, may be included in the adhesive so that when it is exposed to elevated temperatures, crosslinking will occur and the adhesive will acquire further strength both at room temperature and at higher temperatures. When such a cross-linking agent is used, the other ingredients are preferably ones which contain cross-linking sites. It will be apparent to those skilled in the art that these and other common additives such as pigments and stabilizers against ultra violet light may be used singly or in combination.
The ingredients of the adhesive can be mixed together by conventional mixing techniques, for example as described in the Examples be~low. However, it has surprisingly been found that by blending the ingredients at relatively low temperatures, eg. from 50 to 175C, preferably from 50 to 100C, the bond strength obtained under the same bonding conditions is often at least as good as when the ingredients are blended at temperatures above 175C. After the ingredients have been mixed, the mixture i8 preferably granulated (eg. under liquid nigrogen) so as to make it suitable for melt-extrusion. It is also possible to mix the ingredients and to extrude the mixture in a single operation, eg. by use of a twin-screw extruder.
The adhesive preferably has a softening point as determined by Thermomechanical Analysis (TMA), of 60 to 100C, preferably 65 to 90C. When, as is preferred, the adhecive is used as a preform (which may be in the form of a layer on one of the substrates) it is preferably shaped at a temperature which is at least 40C above its softening ~118547 point, but which, when the adhesive is in the form of a layer on one of the substrates, is not so high as to damage the substrate, generally below 250C, preferably 150 to 200C. The adhesive must be heated to its activation temperature before it will bond two substrates together, and it is preferably heated to a temperature of at least 150C, eg. 150 to 220C. Optimum bond strengths are often obtained at relatively high bonding temperatures, eg. 210 to 290C, but especially at temperatures above 220C care must be taken to avoid the formation of bubbles. The bonding temperature need be maintained for a relatively short time, eg. 10 to 30 seconds. The pressure between the substrates during the bonding process is generally S to 25 psi (0.35 to 1.75 kg/cm2), preferably not more than 20 psi (1.4 kg/cm2). When using substrates which are not too thick, it is convenient to subject an assembly of the substrates and the adhesive preform to heat and pressure by means of a press having heated platens.
The invention is illustrated by the following examples in which parts are by weight and temperatures are in degrees Centigrade, except where stated otherwise.
In each of the Examples the adhesive was prepared in a Brabender Plasti-corder. The mixing chamber was preheated to 210, and the fluoroelastomer was introduced, followed by the ethylene copolymer one minute later and the tackifier portionwise four minutes later. Throughout the blending process the temperature was maintained at 210 and the speed of the mixing screws at 25-45 rpm. When the mixture had been rendered homogeneous it was removed and pressed into slabs 10 mil (0.0025 cm) thick in a press having platens coated with poly(tetrafluoroethylene), the pressing being for 30 seconds at 200C and 15,000 psi (1050 kg/cm2).
Test specimens 3 x 1 inch (7.5 x 2.5 cm) were cut from the slabs and bonded to specimens of the various substrates by placing the adhesive test specimen in contact with the substrate for 10 to 50 seconds at 200 to 250 under a pressure of about 20 psi (1.4 kg/cm2). After heat aging in a dry air circulating oven as specified, the adhesive strength was measured either as a 90 or 180 peel value at a peel rate of 10 inches/minute (25 cm/minute) with an Instron tester.
The various ingredients of the adhesives which are identified by their trade names in the Examples below are believed to be materials as further identified below DPD-6169 A copolymer of ethylene and ethyl/acrylate (molar ratio 82:18) having a Melt Index of about 6 Viton A35 A copolymer of vinylidene fluoride and hexafluoropropylene (molar ratio 60:40) having a Mooney viscosity at 100 C of 35 + 5) Piccotex 75 A copolymer of vinyl toluene and O~-methyl styrene having a melting point of about 75C.
Elvax 4260 A copolymer of ethylene, methacrylic acid and vinyl acetate (28 mole %) having a Melt Index of about 6.
Elvax 265 A copolymer of ethylene and vinyl acetate (molar ratio 72:28) having a Melt Index of about 6.
Elvax 360 A copolymer of ethylene and vinyl acetate (molar ratio about 75:25) having a Melt Index of 1.6 to 2.4.
~1~8S47 Viton AHV A copolymer of vinylidene fluoride and hexfluoropropylene (molar ratio 60:40) having a Mooney Viscosity at 100 C of about 160.
The Kynar and Tefzel materials used as substrates in the tests of the adhesives had been cross-linked by irradiation, thus giving them sufficient stability for use in the heat-aging tests.
EXAMPLE I
An adhesive blend (hereafter referred to as Adhesive I) comprising 40 parts Viton A-35, 40 parts DPD 6169, and 20 parts Piccotex 75 was prepared. Its bonding properties to a variety of substrates after heat aging for up to 1000 hours at 150 are given in Table I. As can be seen, outstanding peel strength is retained even to the conclusion of the testO In fact, samples which have been exposed to some heat develop a bond that is stronger than the initial one.
EXAMPLE II
A mixture (designated Adhesive II) comprising 50 parts Elvax 4260, 30 parts Viton A35 and 20 parts Piccotex 75 was prepared and tested as in Example I. The results are given in Table II. Again, the outstanding bond strength after 1000 hours aging at 150 is apparent.
Similar but more viscous adhesives were prepared by using Elvax 265 or a mixture of Elvax 4260 (20 parts) and Elvax 360 (30 parts) in place of the Elvax 4260, and Viton AHV
in place of the Viton A35.
EXAMPLE III
Adhesive blends comprising Viton A35, DPD 6169 and Piccotex 75 were prepared. The tackifier concentration was 20% throughout, but the Viton and DPD 6169 concentrations were varied. Table III shows the effect of varying the Viton concentration on the strength of the bond formed between Tefzel and Kynar. The table shows that the addition of Viton helps adhesion and that maximum improvement occurs at about 30% Viton.
In the 90 peel tests used to evaluate these adhesives the elasticity of the adhesive plays an important role in determining bond strength. An elastic adhesive can deform at the peel junction, thus absorbing much of the stress that would otherwise be transmitted to the adhesive bond.
Thus, the Viton performs the dual function of rendering the adhesive elastically deformable and thermooxidatively stable.
EXAMPLE IV
Adhesive blends comprising Viton A35, DPD 6169, and Piccotex 75 were prepared in which the Viton to DPD 6169 ratio was kept constant while the Piccotex percentage was varied.
Table IV shows the effect of varying the tackifier concentration on the strength of the bond formed between Kynar and Tefzel surfaces, and demonstrates that optimal performance is achieved at a 20% loading of tackifier.
EXAMPLE V
Adhesive blends of 40-50% Elvax 4260, 20 to 30%
Viton A35 and 20% Piccotex 75 were filled with 5 to 20% glass fibers. The effect of varying the glass fiber loading on the mechanical properties of the blends and on the strength of the 111~35~7 bond formed between Stilan and Kynar materials is shown in Table V. Fiber reinforcement of the adhesives to give substantially stiffer material without sacrificing adhesion is possible, and is valuable for situations which require a more rigid adhesive than the unfilled blends.
EXAMPLE VI
To demonstrate the importance of a fluoroelastomer in rendering the adhesives more thermooxidatively stable, a blend of 80% DPD 6169 and 20% Piccotex 75 was prepared and used to bond Stilan to Kynar and Tefzel to Tefzel. The bonded assemblies were then heat aged at 150C. The results, provided in Table VI, show that the adhesives without Viton do not heat age as well. In addition to the numerical data of Table VI, visual inspection of the samples after aging shows that the adhesive is much more brittle than a comparable sample containing Viton.
EXAMPLE VII
Example VI was repeated except that a blend of 30%
Elvax 4260 and 20% Piccotex 75 was used. The results are given in Table VII.
-~--` 152/178 ~8547 Testing of Adhesive I
.Hrs Aged90 Peel Strength Mode of Substrates at 150 lb/in Width Failure SKynar-Tefzel 0 6 to 10 Adhesive-Tefzel " 100 21.1 . Adhesive-Kynar u .. 250 33.7 ,'~ixed " " S00 13.6 Adhesive-Kynar 750 19.5 0 u ~ 1000 22.6 " "
Kynar-Stilan 0 5.9 " 100 1.3 Adhesive-Stilan n 250 1.7 ,- ., u " 500 3.5 " "
" " 750 15.4 " "
" " 1000 10.9 " . "
Tefzel-Ryton 0 8b Adhesive-Tefzel 250 30b Mixed ~ u 500 35b Mixed 20Tefzel-Torlon 0 6b Adhesive-Tefzel 250 15b Mixed u u 500 28b Adhesive-Tefzel ' bl80 peet _ ---15--. . - - .
---~ 152/178 11185~7 TABEE II
: Testing of Adhes;ve II
Hrs Aged90 Peel Strength Mode of Substrates .at 150 lbtin Width Failure 5Tefzel-Kynar 0 6.6 Adhesive-Kynar : ~ " 100 26 " " 250 26 Mixed " " S00 28 "
~ 750 28 " " 1000 24 "
Kynar-Stilan 0 5.8 Adhesive-Stilan " " 100 10.3 " " -" " 250 10.4 " "
" " 500 12.7 " "
" " 750 11.5 " "
~ " 1000 11.7 Tefzel-Ryton 0 6.22 Adhesive-Tefzel " " 250 202 Mixet .
~' " " 500 262 "
20Tefzel-Torlon 0 5~62 Adhesive-Tefzel " " 250 8.62 Mixed " " 500 23.62 Adhesive-Tefzel 2 180 Peel :
-- ---- -15- 1 ~ l 1~85~7 .
- TABLE III
Effect of Yarying Viton Concentration on Bond Strength Percent Yiton A35 Bond Str~Q_h, lb/in 0 5.0 6.7 7~0 8.4 7.4 3.7 ABLE IY
Effect of Piccotex 75 Concentration on Bond Strength Percent Piccotex ?5 T-peel, lb/in 5.6 6.6 5.6 -The Effect of Glass Fibers on Adhesion 90 Peel Strength 20 X Glass Fibers Substrates lb/in (width) pliYoung's Modulus (psi) 0 Stilan-Kynar 5.1 350 " 6.1 1075 " 6.4 5444 n 5.4 5615 " 6.3 12042 .
., ~118547 Heat Aging of a Blend Comprising 80X DP0 6169 and 20~ Piccotex 75 90 Peel, SubstratesHrs at 150 lb/in Mode of Failure _ Stilan-Kynar 250 5.5 Mixed 500 1.9 Adhesive-Stilan 750 1.7 " "
1000 0.8 " "
Tefzel-Tefzel 0 10.0 Adhesive 100 16.6 "
250 11.7 Cohesive : 500 5.2 750 S.0 Adhesive ; 1000 4.5 :; ' ' TABLE VII
1 Heat Aging of a Blend Comprisin~ 80% Elvax 4260 and 20% Piccotex 75 90 Peel, Substratesa Hrs at 150 lb/in Mode of Failure Stilan-Stilan 0 2 Adhesive ~100 4.3 "
250 4.1 500 4.2 "
750 6.0 ~ 1000 5.2 - 25 Tefzel-Tefzel ll.S Adhesive 100 17.5 "
250 10.0 "
SoO 6.8 "
', 750 3.5 "
. .1000 4.Q . "
_
Claims (34)
1. A hot melt adhesive which comprises (1) an ethylene copolymer containing polar groups, (2) a fluorocarbon elastomer, and (3) a tackifier.
2. A hot melt adhesive as claimed in claim 1, which comprises from 10 to 90 % by weight of said ethylene copolymer.
3. A hot melt adhesive as claimed in claim 2, which comprises from 30 to 80 % by weight of said-ethylene copolymer.
4. A hot melt adhesive as claimed in claim 3, which comprises from 40 to 60 % by weight of said ethylene copolymer.
5. A hot melt adhesive as claimed in claim 1, wherein the ethylene copolymer is crystalline.
6. A hot melt adhesive as claimed in claim 1, wherein the ethylene copolymer comprises at least 50 mole % of units derived from ethylene.
7. A hot melt adhesive as claimed in claim 6, wherein the ethylene copolymer comprises at least 60 mole %
of units derived from ethylene.
of units derived from ethylene.
8. A hot melt adhesive as claimed in claim 1, wherein the ethylene copolymer comprises at least 5 mole % of units derived from at least one comonomer containing at least one polar group.
9. A hot melt adhesive as claimed in claim 8, wherein the ethylene copolymer comprises from 10 to 40 mole %
of units derived from at least one comonomer containing at least one polar group.
of units derived from at least one comonomer containing at least one polar group.
10. A hot melt adhesive as claimed in claim 9, wherein the ethylene copolymer comprises from 15 to 25 mole % of units derived from at least one comonomer containing at least one polar group
11. A hot melt adhesive as claimed in claim 1, wherein said polar group is selected from carboxyl, carboxylic ester and alkyl carbonyloxy groups.
12. A hot melt adhesive as claimed in claim 11, wherein said comonomer is selected from vinyl acetate, acrylic acid, methacrylic acid, methyl methacrylate, methyl acrylate and ethyl acrylate.
13. A hot melt adhesive as claimed in claim 1, which comprises from 5 to 60 % by weight of the fluorocarbon elastomer.
14. A hot melt adhesive as claimed in claim 13, which comprises from 10 to 50 % by weight of the fluorocarbon elastomer.
15. A hot melt adhesive as claimed in claim 14, which comprises from 20 to 40 % by weight of the fluorocarbon elastomer.
16. A hot melt adhesive as claimed in claim 1, wherein the fluorocarbon elastomer is a copolymer comprising units derived from at least two fluorinated monoolefinic compounds.
17. A hot melt adhesive as claimed in claim 1, wherein the fluorocarbon elastomer is a copolymer comprising from 30 to 70 mole % of units derived from vinylidene fluoride.
18. A hot melt adhesive as claimed in claim 17, wherein the fluorocarbon elastomer comprises from 70 to 30 mole %
of units derived from hexafluoropropylene, tetrafluoro-ethylene and chlorotrifluoroethylene.
of units derived from hexafluoropropylene, tetrafluoro-ethylene and chlorotrifluoroethylene.
19. A hot melt adhesive as claimed in claim 1, wherein the fluorocarbon elastomer has a Mooney viscosity of from 30 to 160.
20. A hot melt adhesive as claimed in claim 1, which comprises from 5 to 40 % by weight of the tackifier.
21. A hot melt adhesive as claimed in claim 20, which comprises from 10 to 30 % by weight of the tackifier.
22. A hot melt adhesive as claimed in claim 1, wherein the tackifier is a polymer of at least one compound of the formula R1CH = CR2R3 wherein each of R1, R2, and R3, which may be the same or different, represents a substituted or unsubstituted alkyl, alkenyl, aryl, aralkyl or alkaryl radical containing from 1 to 10 carbon atoms.
23. A hot melt adhesive which comprises (1) from 10 to 90 % by weight of a crystalline ethylene copolymer comprising at least 50 mole %
of units derived from at least 5 mole % of units derived from at least one unsaturated comonomer containing at least one polar group;
(2) from 5 to 60 % by weight of a fluorocarbon elastomer consisting of one or more fluorinated monomers containing ethlenic unsaturation and from 0 to 30 mole % other ethylenically unsaturated monomers;
and (3) from 5 to 40 % by weight of a tackifier.
of units derived from at least 5 mole % of units derived from at least one unsaturated comonomer containing at least one polar group;
(2) from 5 to 60 % by weight of a fluorocarbon elastomer consisting of one or more fluorinated monomers containing ethlenic unsaturation and from 0 to 30 mole % other ethylenically unsaturated monomers;
and (3) from 5 to 40 % by weight of a tackifier.
24. A hot melt adhesive which has a softening point of from 60 to 100°C and which comprises (1) from 10 to 90 % by weight of an ethylene copolymer comprising at least 60 mole %
of units derived from ethylene and from 10 to 40 mole % of units derived from at least one comonomer containing polar groups;
(2) from 5 to 60 % by weight of a fluorocarbon elastomer comprising from 30 to 70 mole %
of units derived from vinylidene fluoride and from 70 to 30 mole % of units derived from a comonomer selected from hexafluoro-propylene, tetrafluoroethylene and chloro-trifluoroethylene; and (3) from 5 to 40 % by weight of a tackifier which is a polymer of at least one compound of the formula R1CH = CR2R3 wherein each of R1, R2 and R3, which may be the same or different, represents a substituted or unsubstituted alkyl, alkenyl, aryl, aralkyl or alkaryl radical containing from 1 to 10 carbon atoms.
of units derived from ethylene and from 10 to 40 mole % of units derived from at least one comonomer containing polar groups;
(2) from 5 to 60 % by weight of a fluorocarbon elastomer comprising from 30 to 70 mole %
of units derived from vinylidene fluoride and from 70 to 30 mole % of units derived from a comonomer selected from hexafluoro-propylene, tetrafluoroethylene and chloro-trifluoroethylene; and (3) from 5 to 40 % by weight of a tackifier which is a polymer of at least one compound of the formula R1CH = CR2R3 wherein each of R1, R2 and R3, which may be the same or different, represents a substituted or unsubstituted alkyl, alkenyl, aryl, aralkyl or alkaryl radical containing from 1 to 10 carbon atoms.
25. A hot melt adhesive as claimed in claim 24, which comprises from 30 to 80 % by weight of said ethylene copolymer and from 10 tG 50 % by weight of said fluoro-elastomer.
26. A hot melt adhesive as claimed in claim 25, which comprises from 40 to 60 % by weight of said ethylene copolymer, from 20 to 40 % by weight of said fluoroelastomer and from 10 to 30 % by weight of said tackifier.
27. A heat-recoverable article which comprises a heat-recoverable substrate having a coating on at least part of the surface thereof, in the direction of heat recovery, of a hot melt adhesive as claimed in claim 1.
28. A heat-recoverable article comprising a heat-recoverable substrate having a coating on at least part of the surface thereof, in the direction of heat-recovery of a hot melt adhesive which comprises (1) from 30 to 80 % by weight of an ethylene copolymer comprising at least 60 mole % of units derived from ethylene and from 10 to 40 mole % of units containing polar groups;
(2) from 10 to 50 % by weight of a fluoro-elastomer; and (3) from 5 to 40% by weight of a tackifier.
(2) from 10 to 50 % by weight of a fluoro-elastomer; and (3) from 5 to 40% by weight of a tackifier.
29. A heat-recoverable article as claimed in claim 28, wherein said substrate is composed of a heat-shrinkable cross-linked organic polymer.
30. A heat-recoverable article as claimed in claim 29, wherein said substrate is composed of a polymer selected from the group consisting of polymers of at least one partially fluorinated olefin, copolymers of at least one partially fluorinated olefin and at least one olefin, copolymers of at least one perfluorinated olefin and at least one olefin, and copolymers of at least one partially fluorinated olefin and at least one perfluorinated olefin.
31. A bonded assembly which comprises a first substrate, a second substrate and a layer of a hot melt adhesive which lies between them and bonds them together, said hot melt adhesive being as specified in claim 1.
32. A bonded assembly comprising a first substrate, a second substrate and a layer of a hot melt adhesive which lies between said first and second substrates and bonds them together, said hot melt adhesive comprising (1) from 10 to 90 % by weight of an ethylene copolymer comprising at least 60 mole %
of units derived from ethylene and from 10 to 40 mole % of units derived from at least one comonomer containing at least one polar group.
(2) from 5 to 60 % by weight of a fluorocarbon elastomer comprising from 30 to 70 mole %
of units derived from vinylidene fluoride and from 70 to 30 mole % of units derived from a comonomer selected from hexafluoro-propylene, tetrafluoroethylene and chlorotrifluoroethylene, and (3) from 5 to 40 % by weight of a tackifier and at least one of said substrates being composed of a polymer selected from the group consisting of polymers of at least one partially fluorinated olefin, copolymers of at least one partially fluorinated olefin and at least one olefin, copolymers of at least one perfluorinated olefin and at least one olefin, and copolymers of at least one partially fluorinated olefin and at least one perfluorinated olefin.
of units derived from ethylene and from 10 to 40 mole % of units derived from at least one comonomer containing at least one polar group.
(2) from 5 to 60 % by weight of a fluorocarbon elastomer comprising from 30 to 70 mole %
of units derived from vinylidene fluoride and from 70 to 30 mole % of units derived from a comonomer selected from hexafluoro-propylene, tetrafluoroethylene and chlorotrifluoroethylene, and (3) from 5 to 40 % by weight of a tackifier and at least one of said substrates being composed of a polymer selected from the group consisting of polymers of at least one partially fluorinated olefin, copolymers of at least one partially fluorinated olefin and at least one olefin, copolymers of at least one perfluorinated olefin and at least one olefin, and copolymers of at least one partially fluorinated olefin and at least one perfluorinated olefin.
33. A bonded assembly as claimed in claim 32, wherein said first substrate surrounds said second substrate, is composed of a cross-linked organic polymer and has been heat-shrunk around said second substrate.
34. A bonded assembly as claimed claim 32, wherein at least one of said substrates is an insulating component of an electrical system.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US882,391 | 1978-03-01 | ||
| US05/882,391 US4197380A (en) | 1978-03-01 | 1978-03-01 | Hot melt adhesive comprising fluorocarbon elastomer, ethylene copolymer and tackifier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1118547A true CA1118547A (en) | 1982-02-16 |
Family
ID=25380468
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000322548A Expired CA1118547A (en) | 1978-03-01 | 1979-03-01 | Hot melting adhesive comprising a fluoroelastomer, an ethylene copolymer and a tackifier |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4197380A (en) |
| JP (1) | JPS54160438A (en) |
| CA (1) | CA1118547A (en) |
| DE (1) | DE2907941A1 (en) |
| FR (1) | FR2418810A1 (en) |
| GB (1) | GB1604460A (en) |
| IT (1) | IT1111119B (en) |
| NL (1) | NL7901657A (en) |
| SE (1) | SE7901722L (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4331619A (en) * | 1980-12-08 | 1982-05-25 | Allied Corporation | Ethylene-chlorotrifluoroethylene copolymer foam |
| GB2093053B (en) * | 1981-02-05 | 1984-08-22 | Sumitomo Electric Industries | Fluororubber-based heat-shrinkable tubes |
| US4538881A (en) * | 1983-02-24 | 1985-09-03 | At&T Bell Laboratories | Optical fiber cable including a strain equalizing adhesive which constrains optical loss |
| US4595724A (en) * | 1984-01-24 | 1986-06-17 | Amp Incorporated | Flame retardant sealant |
| JPS6121148A (en) * | 1984-07-10 | 1986-01-29 | Mitsubishi Petrochem Co Ltd | Composition containing thermoplastic fluorine-containing resin |
| GB8418591D0 (en) * | 1984-07-20 | 1984-08-22 | Bp Chem Int Ltd | Polymer composition |
| FR2577564B1 (en) * | 1985-02-14 | 1987-07-17 | Atochem | PROCESS FOR THE SURFACE TREATMENT OF VINYLIDENE POLYFLUORIDE FOR ADHESION TO A SUBSTRATE. MATERIAL OBTAINED FROM TREATED VINYLIDENE POLYFLUORIDE |
| IT1204748B (en) * | 1987-06-19 | 1989-03-10 | Ausimont Spa | COMPOSITIONS BASED ON FLUOROELASTOMERS AND MODIFIED OLEPHINE POLYMERS |
| US5008340A (en) * | 1988-12-21 | 1991-04-16 | Raychem Corporation | Curable adhesives |
| US5059480A (en) * | 1988-12-21 | 1991-10-22 | Raychem Corporation | Curable adhesives |
| EP0489004B1 (en) * | 1988-12-21 | 1995-10-25 | Raychem Corporation | Thermoplastic fluoropolymer adhesive composition |
| US5052610A (en) * | 1988-12-21 | 1991-10-01 | Raychem Corporation | Heat-recoverable soldering device |
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Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3125547A (en) * | 1961-02-09 | 1964-03-17 | Extrudable composition consisting of | |
| NL143973B (en) * | 1965-03-08 | 1974-11-15 | Raychem Corp | PROCESS FOR MAKING POLYURETHANES AND OBJECT FROM A POLYURETHAN MADE THEREFORE FLAME-PROOF. |
| US3562195A (en) * | 1967-12-04 | 1971-02-09 | North American Rockwell | Fluoride elastomer composition |
| CH540946A (en) * | 1970-01-13 | 1973-08-31 | Ochsenbein Astrid O | Polyolefin articles - having adherent surfaces of non-polar polyolefins combined with inomeric ethylene polymer |
-
1978
- 1978-03-01 US US05/882,391 patent/US4197380A/en not_active Expired - Lifetime
- 1978-05-31 GB GB24963/78A patent/GB1604460A/en not_active Expired
-
1979
- 1979-02-26 SE SE7901722A patent/SE7901722L/en not_active Application Discontinuation
- 1979-02-27 FR FR7904977A patent/FR2418810A1/en active Granted
- 1979-02-28 IT IT20641/79A patent/IT1111119B/en active
- 1979-02-28 JP JP2327379A patent/JPS54160438A/en active Pending
- 1979-03-01 NL NL7901657A patent/NL7901657A/en not_active Application Discontinuation
- 1979-03-01 DE DE19792907941 patent/DE2907941A1/en not_active Withdrawn
- 1979-03-01 CA CA000322548A patent/CA1118547A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT1111119B (en) | 1986-01-13 |
| IT7920641A0 (en) | 1979-02-28 |
| FR2418810A1 (en) | 1979-09-28 |
| NL7901657A (en) | 1979-09-04 |
| GB1604460A (en) | 1981-12-09 |
| DE2907941A1 (en) | 1979-09-13 |
| JPS54160438A (en) | 1979-12-19 |
| FR2418810B1 (en) | 1984-06-29 |
| US4197380A (en) | 1980-04-08 |
| SE7901722L (en) | 1979-09-02 |
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