CA1102039A - Radiation curable coating cmpositions containing unsaturated addition - polymerizable urethane resin - Google Patents
Radiation curable coating cmpositions containing unsaturated addition - polymerizable urethane resinInfo
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- CA1102039A CA1102039A CA283,373A CA283373A CA1102039A CA 1102039 A CA1102039 A CA 1102039A CA 283373 A CA283373 A CA 283373A CA 1102039 A CA1102039 A CA 1102039A
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- urethane resin
- unsaturated
- reactive diluent
- weight
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/67—Unsaturated compounds having active hydrogen
- C08G18/671—Unsaturated compounds having only one group containing active hydrogen
- C08G18/672—Esters of acrylic or alkyl acrylic acid having only one group containing active hydrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F299/00—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
- C08F299/02—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates
- C08F299/06—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates from polyurethanes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D4/00—Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16
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- Organic Chemistry (AREA)
- Polymers & Plastics (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Macromonomer-Based Addition Polymer (AREA)
- Paints Or Removers (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
Abstract
Abstract The addition of minor amounts of acrylic acid to radiation curable compositions containing unsaturated addition-poly-merizable urethane resin and reactive monomer diluent is effective in reducing viscosity and thixotropy of the com-positions and in inhibiting separation of the resin phase from the diluent phase. In addition, acrylic acid has been found to render unsaturated addition-polymerizable urethane resins more compatible with higher molecular weight reactive monomer diluents.
Description
ll~Z~39 This invention relates to radiation curablé coa-ting and ink composition. More particularly, the invention relates to radiation curable compositions containing unsaturated addition-polymerizable urethane resin.
Increasing concern with energy, environmental protection, and health factors have cooperated to enhance the potential of radiation curable coatings. In principle, such coatings com-prise a polymerizable mixture that can be applied as a thin film to a substrate and polymerized at a rapid rate by exposure to a radiation source such as an electron beam, plasma arc, ultra violet light, and the like. Advantages of radiation curable coatings include a practical method of at least reducing air pollution from volatile vapor loss, rapid cure rates at ambient temperatures, reduced operating costs, the use of heat-sensitive substrates, and improved product performance.
Among the more notable achievements in the field of radiation curing has been the development of the so-called 100 percent reactive solids systems based on unsaturated addition-polymerizable urethane resin. A characteristic feature of such systems is the substantial absence of conventional inert volatile solvents. Instead, the systems contain reactive diluents which react during curing to become an integral part of the cured coating. Such systems have been widely accepted commer-cially. ~hile such systems provide high-performance coatings which can be cured at high line speeds, they have also provided a new set of problems for the coatings formulators.
While unsaturated addition-polymerizable urethane resins can be prepared by several known reaction routes, the preferred method of preparation for obtaining premium-quality coatings is by capping an isocyanate-functional prepolymer with an appropriate addition-polymerizable monomer having a single isocyanate-reactive active hydrogen group, with the reaction being effected ~2~39 in the presence of a diluent system which is inert with respect to the capping reaction but which is reactive at cure conditions with the unsaturated addition-polymerizable urethane resins.
One particularly vexing problem of compositions containing such polymerizable urethane resins, regardless of how the resin is prepared, is the high viscosity of the resin compositions which makes application by conventional industrial techniques difficult, if not impossible. Because the use of conventional inert sol-vents such as are employed with moisture-cure polyurethanes is undesirable, there has been developed the so-called reactive diluent systems, which generally comprise a mixture of mono-functional and polyfunctional unsaturated addition-polymerizable monomeric compounds which are copolymerizable with the addition polymerizable urethane resin and thus become part of the cured coating. Certain of the lower molecular weight monomeric diluents such as butyl acrylate are effective in affording clear coating compositions which can be applied by conventional indust-rial techniques; however, their use is often undesirable because of their relatively high volatility, toxicity, noxiousness and other hazards. While higher molecular weight diluents such as
Increasing concern with energy, environmental protection, and health factors have cooperated to enhance the potential of radiation curable coatings. In principle, such coatings com-prise a polymerizable mixture that can be applied as a thin film to a substrate and polymerized at a rapid rate by exposure to a radiation source such as an electron beam, plasma arc, ultra violet light, and the like. Advantages of radiation curable coatings include a practical method of at least reducing air pollution from volatile vapor loss, rapid cure rates at ambient temperatures, reduced operating costs, the use of heat-sensitive substrates, and improved product performance.
Among the more notable achievements in the field of radiation curing has been the development of the so-called 100 percent reactive solids systems based on unsaturated addition-polymerizable urethane resin. A characteristic feature of such systems is the substantial absence of conventional inert volatile solvents. Instead, the systems contain reactive diluents which react during curing to become an integral part of the cured coating. Such systems have been widely accepted commer-cially. ~hile such systems provide high-performance coatings which can be cured at high line speeds, they have also provided a new set of problems for the coatings formulators.
While unsaturated addition-polymerizable urethane resins can be prepared by several known reaction routes, the preferred method of preparation for obtaining premium-quality coatings is by capping an isocyanate-functional prepolymer with an appropriate addition-polymerizable monomer having a single isocyanate-reactive active hydrogen group, with the reaction being effected ~2~39 in the presence of a diluent system which is inert with respect to the capping reaction but which is reactive at cure conditions with the unsaturated addition-polymerizable urethane resins.
One particularly vexing problem of compositions containing such polymerizable urethane resins, regardless of how the resin is prepared, is the high viscosity of the resin compositions which makes application by conventional industrial techniques difficult, if not impossible. Because the use of conventional inert sol-vents such as are employed with moisture-cure polyurethanes is undesirable, there has been developed the so-called reactive diluent systems, which generally comprise a mixture of mono-functional and polyfunctional unsaturated addition-polymerizable monomeric compounds which are copolymerizable with the addition polymerizable urethane resin and thus become part of the cured coating. Certain of the lower molecular weight monomeric diluents such as butyl acrylate are effective in affording clear coating compositions which can be applied by conventional indust-rial techniques; however, their use is often undesirable because of their relatively high volatility, toxicity, noxiousness and other hazards. While higher molecular weight diluents such as
2-ethyl hexyl acrylate, octyl acrylate, stearyl acrylate and the like are preferred because they do not present the volatility, toxicity and handling problems associated with their lower molecular weight counterparts, they are not without their problems. Generally, greater amounts of the preferred higher molecular weight diluents are required for effective viscosity reduction. A particularly undesirable phenomenon which is characteristic of diluent systems containing the higher mole-cular weight reactive monomer diluents is physical instability of the composition which results in thixotropy or cloudiness leading to eventual separation of the compositions into distinct resin-rich and monomer-rich phases. The adverse phenomena ~132~39 appear common to all diluent systems con-taining the higher molecular diluents and is most likely to occur with compositions containing hiqher molecular weight resinous components. Thus, there appears to be a maximum diluent level, which varies with the amount and composition of higher molecular weight diluent present in the diluent system, that the unsaturated addition-polymerizable urethane resins can tolerate before separation takes place. The abilitv to produce compositions which will remain homogeneous and which can be readily and uniformly applied to substrates and rapidly cured to a dried film is of important commercial importance. It is equally important that harmful emissions to the atmosphere be minimized and that toxic, noxious and otherhealth hazards be at least reduced, if not entirely eliminated.
During the course of an extensive study of the viscosity and thixotropy of radiation curable compositions, particularly such compositions containing unsaturated addition-polymerizable urethane resins, it was discovered that the addition of minor amounts of acrylic acid to radiation curable compositions has the unexpected and inexplainable effects of inhibiting, if not entirely eliminating, physical instability as the reactive diluent level increases, causing an increase in flowability;
and affording significant improvements in cured film properties;
the effects being out of proportion to the amount of free acrylic acid employed. One measure of this inexplainable effect is that the use of methacrylic acid, among other organic and inorganic acids, does not afford the same benefits as are obtained with acrylic acid. The present invention permits the use of higher molecular weight reactive monomer diluents such as 2-ethyl hexyl acrylate at hiqher diluent levels than heretofore. As well, the present invention provides compositionshaving a more manageable viscosity at higher resin content than heretofore ,~ .
~Z~39 possible.
In accordance with the present invention, there are provided radiation curable compositions comprising A. at least one unsaturated addition polymerizable urethane resin;
B. a reactive diluent system comprising at least one unsaturated addition-polymerizable monoEunctional monomeric compound selected from the group consisting of esters having the general formula O
CH2 = C - C - O - R, 1o wherein R is hydrogen or methvl and R is an aliphatic or cyclo-aliphatic, preferably alkyl or cycloalkyl, group having from 6 to 18, preferably 6 to 9, carbon atoms;
C. from about 0.1 to about 10, preferably about 1 to about 5, weight percent, based on total weight of said unsaturated addition-polymerizable urethane resin and total reactive diluent system, of acrylic acid; and optionally, D. an effective amount of at least one photoinitiator;
the amount of unsaturated addition polymerizable urethane resin being in the range from about 30 to about 90, preferably from about 50 to about 75, weight percent, based on combined weight of unsaturated addition-polymerizable urethane resin and reactive diluent system. The photoinitiator, which will generally be employed when curing is effected with a low energy radiation source such as ultraviolet light radiation, will generally be in the range from about 0.01 to about 30, preferably about 0.1 to about 15, parts by weight per 100 parts by combined weight of unsaturated addition-polymerizable resin and reactive diluent system.
1~2~39 The unsaturated addition-polymerizable urethane resins which are suitable for use in the practice of the invention are characterized by the presence of at least one, preferably at least two, polymerizable ethylenically unsaturated group(s) having the structure \ C=C ~ . The polymerizable ethylenically unsaturated group is preferably a terminal vinyl group having the structure CH2 = C ~ . Especially preferred unsaturated addition polymerizable urethane resins are the acrylyl urethane resins, i.e., urethane resins containing a polymerizable acrylyl/ methacrylyl, acrylamide, methacrylamide, and the like moiety in the molecule, characterized by the presence of at least one, preferably at least two, terminal ethylenically unsaturated group(s) having the structure CH2=C ~ . For brevity, the unsaturated addition-polymerizable urethane resins will be referred to hereinafter in this disclosure and the ensuing claims as unsaturated urethane resins. Such unsaturated urethane resins are well-known in the art and do not require further elaboration herein. A particularly preferred class of unsaturated urethane resins are those obtained by fully capping an isocyanate-functional prepolymer with an appropriate unsaturated addition-polymerizable monomer, e.g., 2-hydroxyethyl acrylate, especially such unsaturated urethane resins derived from isocyanate-functional- prepolymers obtained by reacting at least one polyisocyanate and at least one polyol at an NCO:OH ratio greater than 2:1.
A further essential ingredient of the coating compositions of this invention comprises a reactive diluent system. Broadly, the reactive diluent comprises at least one unsaturated addition-polymerizable monomer which is copolymerizable with the un-saturated resin upon exposure to radiation. In the generalcase, such unsaturated addition-polymerizable monomeric diluents can be monofunctional or polyfunctional with combinations of one i~2~)3g or more monofunctional reactive diluents and one or more poly-functional reactive diluents heinq presently preferred. In the case of the present invention, the reactive diluent systems contain at least one unsaturated addition-polymerizable monofunctional monomeric compound selected from the group con-sisting of esters having the qeneral formula O
CH2 = C - C - O - R, R
wherein R is hvdroqen or methyl and R is an aliphatic or cvclo-aliphatic, preferably alkyl or cycloalkyl, group having from 6 .
to 18, preferably 6 to 9 carbon atoms. Representative of such esters are hexyl acrylate, cyclohexyl acrylate, 2-ethyl hexyl acrylate, octvl acrylate, nonyl acrylate, stearyl acrylate, and the corresponding methacrylates. Optionally, the diluent systems can contain one or more of the known reactive monofunctional monomeric diluents in addition to the required acrylic and meth-acrylic esters havinq at least 6 carbon atoms inthe non-acid moiety of the molecule. In many instances, the reactive diluent systems advantageously will include one or more reactive poly-functional monomeric diluents. Suchoptional reactivemonofuncti~nal andpolvfunctional monomericdi~luents include,wi~hout limitation thereto,styrene, methylmethacrylate, butylacrylate, isobutylacrylate,;
dicyclopentenyl acrylate, 2-phenoxyethylacrylate, 2-methoxyethyl acrylate, 2-(N,N-diethylamino)-ethyl acrylate, the corresponding methacrylates, acrylonitrile, methacrylonitrile, methacrylamide, ' :
neopentyl glycol diacrylate, ethylene qlycol diacrylate, hexylene glycol diacrylate, diethylene glycol diacrylate, trimethylol propane triacrylate, pentaerythritol di-, tri-, or tetra-acrvlate, the corresponding methacrylates, vinyl acrylate, vinylmethacrvlate and the like. Generally, the reactive diluent system will comprise from about 10 to about 70, preferably about 25 to about 50, weiqht percent, based on total weight of .~
~ - 6 -1~2~S'39 unsaturated urethane resin and reactlve diluent system of the radiation curable compositions of the invention. It is presently preferred that the diluent system contain at least 50 weight per-cent of acrylic and methacrvlic esters havina at least 6 carbon atoms in the non-acid moiety of the molecule. Reactive diluent systems are well-known to those skilled in the art of radiation curing and the selection of an appropriate diluent system in any given instance is sufficiently encompassed by such knowledge as to require no further discussion here.
As previously indicated, a photoinitiator system will generally be employed when curinq is effected by exposure to low energy radiation sources such as ultra violet light. Any of the known photoinitiators can be used within the concentration ranges previously set forth. Illustrative photoinitiators, without limitation thereto, include benzophenone, benzoin, acetophenone, benzoin methyl ether, ~lichler's ketone, benzoin butyl ether, xanthone, thioxanthone, propiophenone, fluorenone, carbazole, diethoxyacetophenone, the 2-, 3- and 4-methylaceto-phenones and methoxyacetophenones, the 2- and 3-chloroxanthones and chlorothioxanthones, 2-acetyl-4-methylphenyl acetate, 2,2'-dimethoxy-2-phenylacetophenone, benzaldehyde, fluorene, anthroquinone, triphenylamine, 3- and 4-allylacetophenone, p-diacetylbenzene, 3-chloro-2-nonylxanthone, and the like, and mixtures thereof.
~ The invention compositions can also include pigments, fillers, wetting aqents, flatting agents, and other additives typically present in coating compositions, with the exception of inert volatile solvents or diluents. These are well-known to those skilled in the art and do not require further elaboration herein. Also well-known are the concentrations at which such additives are used.
The radiation curable compositions of the present invention i~2~39 have an increased flowability and fluidity, and exhibit a markedly improved viscositv stabilitv, i.e., a substantially reduced tendency to phasing, at any diluent level in comparison to compositions which do not contain any free acrylic acid.
Thus, the invention compositions can be applied to wood, metal fabric and plastic substrates in a more economical and efficient manner to afford a smoother and more uniform film. In addition, the modulus andultimate film properties or cured films derived from the compositions of this invention arenoticeably better than the corresponding properties of cured films derived from radiation curable compositions which do not contain any free acrylic acid.
The improved coating compositions of this invention can be applied and cured by any of the conventional known methods.
Application can be by roll coating, curtain coating, airless spray, dipping or by any other procedure. The cure can be effected by exposure to anv high energy source, such as ionizing radiation, or low eneray source, such as ultraviolet light radiation. The equipment utilized for curing, as well and the appropriate time for curing, and the conditions under which the curing is effected are well-known to those skilled in the art of radiation curing and do not require further elaboration herein.
The invention is illustrated in greater detail by the following Examples, but these examples are not to be construed as limiting the present invention. All parts, percentages and the like are in parts by weight, unless otherwise indicated.
Example I
An unsaturated acrylvl urethane resin composition is prepared by reacting methylene-bis(cvclohexyl isocyanate) and polycaprolacetone triol having an average molecular weight of about 900 in the presence of 2-ethyl hexyl acrylate and Z~39 stannous octoate at an NCO:OH mol ratio of 2.5:1. The reaction is terminated at an end point corresponding to 100 percent depletion of hydroxyl value, as determined by isocyanate titration. When the end point is reached there is immediately added to the isocyanate-functional prepolymer-containing reaction mixture sufficient 2-hydroxyethyl acrylate to react with the free isocyanate functions of the prepolymer. Radiation curable compositions are prepared at several diluent (2-ethyl hexyl acrylate) levels with the following results:
Composition A B C
Unsaturated urethane resin 70 65 60 2-ethyl hexyl acrylate30 35 40 Time to separationa2 mos 30 days 24 hrs Viscosity, cps 27,500 12,000 8,400 a = separation of composition into distinct resin-rich and monomer-rich phases The data are demonstrative of the physical instability of radiation curable compositions comprising unsaturated urethane resin and reactive diluent system containing acrylic and meth-acrylic acid esters having at least 6 carbon atoms in the non-acid moiety of the ester molecule.
Example II
Composition C of Example I is heated at 58C for 30 minutes with constant stirring. The resin phase is redispersed into the diluent phase to form a homogeneous system. The composition is now separated into four separate portions. After standing for 24 hours, phasing has occurred in each portion.
To three portions, there is added acrylic acid at 1, 3 and 5 percent levels. In each instance, the addition of acrylic acid results in resolubilization of the separated unsaturated urethane.
Also in each instance, the addition of acrylic acid significantly reduces the viscosity and thixotropy of the composition to _ g _ ~1~2~39 marked increase the flow abilityof the compositions. The results are tabulated below:
Composition C C-l C-2 C-3 Unsaturated urethane 60 60 6060 2-ethyl hexyl acrylate 40 40 4040 Acrylic acid, weight percent 0 1 3 5 Viscosity, cps 8,400 5,600 3,8003,000 Time to separation 24 hrs 2 mos >2 mos >2 mos To each of compositions C, C-l, C-2 and C-3 is added an effective amount of a henzoin-type photoinitiator. The com-positions are then coated onto aluminum panels and cured by exposure to ultravoilet radiation (200 watts/in.) at a line - speed of 50 feed per minute for three passes. Compositions C-l, C-2 and C-3are sianificantlyless viscous and are more easily and uniformly applied to the substrate than is composition C, which contains no acrylie acid. In the ease of Composition C, phasing aqain oecurs within 24 hours; nodiscernible phasing is observed with anv of compositions C-l, C-2 and C-3 after two months storage. The properties of the cured films are tabulated helow:
Composition C C-l C-2 C-3 Tensile strength, psi 3816 3065 3570 4480 Youngs modulus, psi 77000 75000 92000 118000 The data demonstrate the unexpected effects afforded by the present invention in reducing viscosity and thixotropy of radiation curable eompositions, improvina viscosity stability, and significantly improving cured film properties.
Example III
Emplovinq the unsaturated acrylyl urethane resin composition of Example I, the following formulation is prepared:
: Unsaturated urethane 60 2-ethyl hexyl acrylate 40 ~t;32~
The formulation is divided into several portions. After 24 hours at room temperature, phase separation has occured with each portion. There is added to individual portions acrylic acid, methacrylic acid, acetic acid, p-toluene sulfonie acid and hydrochloric acid, respectively, at a level of 3 weight pereent, based on total weight of urethane resin and diluent system. Acetie acid, p-toluene sulfonie aeid and hvdroehlorie aeid do not resoluhilize the resin phase. The resin phase is resolubilized by the addition of methaerylic acid but phasing again occurs within 24 hours. The resin phase is resolubilized by the addition of acrylic aeid and substantially no phasing has oeeurred after 2 months storage. The data demonstrates the eompletely unexpeeted results whieh are obtained by the addition of minor amounts of acrylie acid to radiation curable compositions.
~r ~,, - 11 -
During the course of an extensive study of the viscosity and thixotropy of radiation curable compositions, particularly such compositions containing unsaturated addition-polymerizable urethane resins, it was discovered that the addition of minor amounts of acrylic acid to radiation curable compositions has the unexpected and inexplainable effects of inhibiting, if not entirely eliminating, physical instability as the reactive diluent level increases, causing an increase in flowability;
and affording significant improvements in cured film properties;
the effects being out of proportion to the amount of free acrylic acid employed. One measure of this inexplainable effect is that the use of methacrylic acid, among other organic and inorganic acids, does not afford the same benefits as are obtained with acrylic acid. The present invention permits the use of higher molecular weight reactive monomer diluents such as 2-ethyl hexyl acrylate at hiqher diluent levels than heretofore. As well, the present invention provides compositionshaving a more manageable viscosity at higher resin content than heretofore ,~ .
~Z~39 possible.
In accordance with the present invention, there are provided radiation curable compositions comprising A. at least one unsaturated addition polymerizable urethane resin;
B. a reactive diluent system comprising at least one unsaturated addition-polymerizable monoEunctional monomeric compound selected from the group consisting of esters having the general formula O
CH2 = C - C - O - R, 1o wherein R is hydrogen or methvl and R is an aliphatic or cyclo-aliphatic, preferably alkyl or cycloalkyl, group having from 6 to 18, preferably 6 to 9, carbon atoms;
C. from about 0.1 to about 10, preferably about 1 to about 5, weight percent, based on total weight of said unsaturated addition-polymerizable urethane resin and total reactive diluent system, of acrylic acid; and optionally, D. an effective amount of at least one photoinitiator;
the amount of unsaturated addition polymerizable urethane resin being in the range from about 30 to about 90, preferably from about 50 to about 75, weight percent, based on combined weight of unsaturated addition-polymerizable urethane resin and reactive diluent system. The photoinitiator, which will generally be employed when curing is effected with a low energy radiation source such as ultraviolet light radiation, will generally be in the range from about 0.01 to about 30, preferably about 0.1 to about 15, parts by weight per 100 parts by combined weight of unsaturated addition-polymerizable resin and reactive diluent system.
1~2~39 The unsaturated addition-polymerizable urethane resins which are suitable for use in the practice of the invention are characterized by the presence of at least one, preferably at least two, polymerizable ethylenically unsaturated group(s) having the structure \ C=C ~ . The polymerizable ethylenically unsaturated group is preferably a terminal vinyl group having the structure CH2 = C ~ . Especially preferred unsaturated addition polymerizable urethane resins are the acrylyl urethane resins, i.e., urethane resins containing a polymerizable acrylyl/ methacrylyl, acrylamide, methacrylamide, and the like moiety in the molecule, characterized by the presence of at least one, preferably at least two, terminal ethylenically unsaturated group(s) having the structure CH2=C ~ . For brevity, the unsaturated addition-polymerizable urethane resins will be referred to hereinafter in this disclosure and the ensuing claims as unsaturated urethane resins. Such unsaturated urethane resins are well-known in the art and do not require further elaboration herein. A particularly preferred class of unsaturated urethane resins are those obtained by fully capping an isocyanate-functional prepolymer with an appropriate unsaturated addition-polymerizable monomer, e.g., 2-hydroxyethyl acrylate, especially such unsaturated urethane resins derived from isocyanate-functional- prepolymers obtained by reacting at least one polyisocyanate and at least one polyol at an NCO:OH ratio greater than 2:1.
A further essential ingredient of the coating compositions of this invention comprises a reactive diluent system. Broadly, the reactive diluent comprises at least one unsaturated addition-polymerizable monomer which is copolymerizable with the un-saturated resin upon exposure to radiation. In the generalcase, such unsaturated addition-polymerizable monomeric diluents can be monofunctional or polyfunctional with combinations of one i~2~)3g or more monofunctional reactive diluents and one or more poly-functional reactive diluents heinq presently preferred. In the case of the present invention, the reactive diluent systems contain at least one unsaturated addition-polymerizable monofunctional monomeric compound selected from the group con-sisting of esters having the qeneral formula O
CH2 = C - C - O - R, R
wherein R is hvdroqen or methyl and R is an aliphatic or cvclo-aliphatic, preferably alkyl or cycloalkyl, group having from 6 .
to 18, preferably 6 to 9 carbon atoms. Representative of such esters are hexyl acrylate, cyclohexyl acrylate, 2-ethyl hexyl acrylate, octvl acrylate, nonyl acrylate, stearyl acrylate, and the corresponding methacrylates. Optionally, the diluent systems can contain one or more of the known reactive monofunctional monomeric diluents in addition to the required acrylic and meth-acrylic esters havinq at least 6 carbon atoms inthe non-acid moiety of the molecule. In many instances, the reactive diluent systems advantageously will include one or more reactive poly-functional monomeric diluents. Suchoptional reactivemonofuncti~nal andpolvfunctional monomericdi~luents include,wi~hout limitation thereto,styrene, methylmethacrylate, butylacrylate, isobutylacrylate,;
dicyclopentenyl acrylate, 2-phenoxyethylacrylate, 2-methoxyethyl acrylate, 2-(N,N-diethylamino)-ethyl acrylate, the corresponding methacrylates, acrylonitrile, methacrylonitrile, methacrylamide, ' :
neopentyl glycol diacrylate, ethylene qlycol diacrylate, hexylene glycol diacrylate, diethylene glycol diacrylate, trimethylol propane triacrylate, pentaerythritol di-, tri-, or tetra-acrvlate, the corresponding methacrylates, vinyl acrylate, vinylmethacrvlate and the like. Generally, the reactive diluent system will comprise from about 10 to about 70, preferably about 25 to about 50, weiqht percent, based on total weight of .~
~ - 6 -1~2~S'39 unsaturated urethane resin and reactlve diluent system of the radiation curable compositions of the invention. It is presently preferred that the diluent system contain at least 50 weight per-cent of acrylic and methacrvlic esters havina at least 6 carbon atoms in the non-acid moiety of the molecule. Reactive diluent systems are well-known to those skilled in the art of radiation curing and the selection of an appropriate diluent system in any given instance is sufficiently encompassed by such knowledge as to require no further discussion here.
As previously indicated, a photoinitiator system will generally be employed when curinq is effected by exposure to low energy radiation sources such as ultra violet light. Any of the known photoinitiators can be used within the concentration ranges previously set forth. Illustrative photoinitiators, without limitation thereto, include benzophenone, benzoin, acetophenone, benzoin methyl ether, ~lichler's ketone, benzoin butyl ether, xanthone, thioxanthone, propiophenone, fluorenone, carbazole, diethoxyacetophenone, the 2-, 3- and 4-methylaceto-phenones and methoxyacetophenones, the 2- and 3-chloroxanthones and chlorothioxanthones, 2-acetyl-4-methylphenyl acetate, 2,2'-dimethoxy-2-phenylacetophenone, benzaldehyde, fluorene, anthroquinone, triphenylamine, 3- and 4-allylacetophenone, p-diacetylbenzene, 3-chloro-2-nonylxanthone, and the like, and mixtures thereof.
~ The invention compositions can also include pigments, fillers, wetting aqents, flatting agents, and other additives typically present in coating compositions, with the exception of inert volatile solvents or diluents. These are well-known to those skilled in the art and do not require further elaboration herein. Also well-known are the concentrations at which such additives are used.
The radiation curable compositions of the present invention i~2~39 have an increased flowability and fluidity, and exhibit a markedly improved viscositv stabilitv, i.e., a substantially reduced tendency to phasing, at any diluent level in comparison to compositions which do not contain any free acrylic acid.
Thus, the invention compositions can be applied to wood, metal fabric and plastic substrates in a more economical and efficient manner to afford a smoother and more uniform film. In addition, the modulus andultimate film properties or cured films derived from the compositions of this invention arenoticeably better than the corresponding properties of cured films derived from radiation curable compositions which do not contain any free acrylic acid.
The improved coating compositions of this invention can be applied and cured by any of the conventional known methods.
Application can be by roll coating, curtain coating, airless spray, dipping or by any other procedure. The cure can be effected by exposure to anv high energy source, such as ionizing radiation, or low eneray source, such as ultraviolet light radiation. The equipment utilized for curing, as well and the appropriate time for curing, and the conditions under which the curing is effected are well-known to those skilled in the art of radiation curing and do not require further elaboration herein.
The invention is illustrated in greater detail by the following Examples, but these examples are not to be construed as limiting the present invention. All parts, percentages and the like are in parts by weight, unless otherwise indicated.
Example I
An unsaturated acrylvl urethane resin composition is prepared by reacting methylene-bis(cvclohexyl isocyanate) and polycaprolacetone triol having an average molecular weight of about 900 in the presence of 2-ethyl hexyl acrylate and Z~39 stannous octoate at an NCO:OH mol ratio of 2.5:1. The reaction is terminated at an end point corresponding to 100 percent depletion of hydroxyl value, as determined by isocyanate titration. When the end point is reached there is immediately added to the isocyanate-functional prepolymer-containing reaction mixture sufficient 2-hydroxyethyl acrylate to react with the free isocyanate functions of the prepolymer. Radiation curable compositions are prepared at several diluent (2-ethyl hexyl acrylate) levels with the following results:
Composition A B C
Unsaturated urethane resin 70 65 60 2-ethyl hexyl acrylate30 35 40 Time to separationa2 mos 30 days 24 hrs Viscosity, cps 27,500 12,000 8,400 a = separation of composition into distinct resin-rich and monomer-rich phases The data are demonstrative of the physical instability of radiation curable compositions comprising unsaturated urethane resin and reactive diluent system containing acrylic and meth-acrylic acid esters having at least 6 carbon atoms in the non-acid moiety of the ester molecule.
Example II
Composition C of Example I is heated at 58C for 30 minutes with constant stirring. The resin phase is redispersed into the diluent phase to form a homogeneous system. The composition is now separated into four separate portions. After standing for 24 hours, phasing has occurred in each portion.
To three portions, there is added acrylic acid at 1, 3 and 5 percent levels. In each instance, the addition of acrylic acid results in resolubilization of the separated unsaturated urethane.
Also in each instance, the addition of acrylic acid significantly reduces the viscosity and thixotropy of the composition to _ g _ ~1~2~39 marked increase the flow abilityof the compositions. The results are tabulated below:
Composition C C-l C-2 C-3 Unsaturated urethane 60 60 6060 2-ethyl hexyl acrylate 40 40 4040 Acrylic acid, weight percent 0 1 3 5 Viscosity, cps 8,400 5,600 3,8003,000 Time to separation 24 hrs 2 mos >2 mos >2 mos To each of compositions C, C-l, C-2 and C-3 is added an effective amount of a henzoin-type photoinitiator. The com-positions are then coated onto aluminum panels and cured by exposure to ultravoilet radiation (200 watts/in.) at a line - speed of 50 feed per minute for three passes. Compositions C-l, C-2 and C-3are sianificantlyless viscous and are more easily and uniformly applied to the substrate than is composition C, which contains no acrylie acid. In the ease of Composition C, phasing aqain oecurs within 24 hours; nodiscernible phasing is observed with anv of compositions C-l, C-2 and C-3 after two months storage. The properties of the cured films are tabulated helow:
Composition C C-l C-2 C-3 Tensile strength, psi 3816 3065 3570 4480 Youngs modulus, psi 77000 75000 92000 118000 The data demonstrate the unexpected effects afforded by the present invention in reducing viscosity and thixotropy of radiation curable eompositions, improvina viscosity stability, and significantly improving cured film properties.
Example III
Emplovinq the unsaturated acrylyl urethane resin composition of Example I, the following formulation is prepared:
: Unsaturated urethane 60 2-ethyl hexyl acrylate 40 ~t;32~
The formulation is divided into several portions. After 24 hours at room temperature, phase separation has occured with each portion. There is added to individual portions acrylic acid, methacrylic acid, acetic acid, p-toluene sulfonie acid and hydrochloric acid, respectively, at a level of 3 weight pereent, based on total weight of urethane resin and diluent system. Acetie acid, p-toluene sulfonie aeid and hvdroehlorie aeid do not resoluhilize the resin phase. The resin phase is resolubilized by the addition of methaerylic acid but phasing again occurs within 24 hours. The resin phase is resolubilized by the addition of acrylic aeid and substantially no phasing has oeeurred after 2 months storage. The data demonstrates the eompletely unexpeeted results whieh are obtained by the addition of minor amounts of acrylie acid to radiation curable compositions.
~r ~,, - 11 -
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A coating composition comprising: a) at least one unsaturated addition polymerizable urethane resin; (b) a reactive diluent system containing at least one unsaturated addition-polymerizable monofunctional monomeric compound selected from the group consisting of esters having the general formula ;
wherein R° is hydrogen or methyl and R is an aliphatic or cyclo-aliphatic group having from 6 to 18 carbon atoms; and (c) acrylic acid, the amount of said unsaturated resin being in the range from about 30 to about 90 weight percent, based on combined weight of said unsaturated urethane resin and said reactive diluent system, the amount of the reactive diluent system being from 10 to 70% by weight based on the total weight of unsaturated urethane resin and reactive diluent system, and the amount of acrylic acid being in the range from about 0.1 to about 10 weight percent, based on total weight of said unsaturated urethane resin and said reactive diluent system.
wherein R° is hydrogen or methyl and R is an aliphatic or cyclo-aliphatic group having from 6 to 18 carbon atoms; and (c) acrylic acid, the amount of said unsaturated resin being in the range from about 30 to about 90 weight percent, based on combined weight of said unsaturated urethane resin and said reactive diluent system, the amount of the reactive diluent system being from 10 to 70% by weight based on the total weight of unsaturated urethane resin and reactive diluent system, and the amount of acrylic acid being in the range from about 0.1 to about 10 weight percent, based on total weight of said unsaturated urethane resin and said reactive diluent system.
2. A composition according to claim 1, wherein the amount of said unsaturated resin is in the range from about 50 to about 75 weight percent based on combined weight of said unsaturated urethane resin and said reactive diluent system.
3. A composition according to claim 2, wherein the amount of acrylic acid is in the range from about 1 to about 5 weight percent, based on total weight of said unsaturated urethane resin and said reactive diluent system.
4. A composition according to claim 3, wherein said unsaturated urethane resin is characterized by the presence of at least two terminal ethylenically unsaturated groups having the structure .
5. A composition according to claim 3, containing an effective amount of at least one photoinitiator compound.
6. A composition according to claim 4, containing from about 0.01 to about 30 parts by weight, based on combined weight of said unsaturated urethane resin and said reactive diluent system, of at least one photoinitiator compound.
7. A composition according to claim 2, wherein R is an alkyl or cycloalkyl group having from 6 to 18 carbon atoms.
8. A composition according to claim 2, wherein R is an alkyl or cycloalkyl group having from 6 to 9 carbon atoms.
9. A composition according to claim 8, wherein said unsaturated urethane resin is characterized by the presence of at least two terminal ethylenically unsaturated groups having the structure .
10. A composition according to claim 9 containing from about 0.01 to about 30 parts by weight, based on combined weight of said unsaturated urethane resin and said reactive diluent system, of at least one photoinitiator compound.
11. A composition according to claim 10 wherein the amount of said unsaturated urethane resin is in the range of about 50 to about 75 weight percent.
12. A composition according to claim 11, wherein said unsaturated urethane resin is derived from an isocyanate-functional prepolymer obtained by reacting a polyol having at least two hydroxyl groups and a polyisocyanate having at least two isocyanate groups at an NCO:OH ratio greater than 2:1.
13. A composition according to claim 4 wherein R° is hydrogen and R is 2-ethyl hexyl.
14. A composition according to claim 6, wherein R°
is hydrogen and R is 2-ethyl hexyl.
is hydrogen and R is 2-ethyl hexyl.
15. A composition according to claim 11, wherein R° is hydrogen and R is 2-ethyl hexyl.
16. A composition according to claim 12, wherein R° is hydrogen and R is 2-ethyl hexyl.
17. A composition according to claim 11, wherein the amount of acrylic acid is in the range from about 1 to about 5 percent.
18. A composition according to claim 17, wherein said unsaturated urethane resin is derived from an isocyanate-functional prepolymer obtained by reacting at least one polyol having at least two hydroxyl groups and at least one polyisocyanate having at least two isocyanate groups at an NCO:OH ratio greater than 2:1.
19. A composition according to claim 18, wherein R0 is hydrogen and R is 2-ethyl hexyl.
20. A method for coating a substrate comprising apply-ing to said substrate a coating composition according to claim 5;
and exposing said coated substrate to ultraviolet irradiation for a time sufficient to cure said coating to a hard mar-resistant surface.
and exposing said coated substrate to ultraviolet irradiation for a time sufficient to cure said coating to a hard mar-resistant surface.
21. A coated substrate having a hard mar-resistant sur-face which coating is an ultraviolet irradiation cured coating composition as claimed in claim 5.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70825276A | 1976-07-23 | 1976-07-23 | |
| US708,252 | 1976-07-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1102039A true CA1102039A (en) | 1981-05-26 |
Family
ID=24845028
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,373A Expired CA1102039A (en) | 1976-07-23 | 1977-07-22 | Radiation curable coating cmpositions containing unsaturated addition - polymerizable urethane resin |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5313644A (en) |
| AU (1) | AU516747B2 (en) |
| CA (1) | CA1102039A (en) |
| DE (1) | DE2733038A1 (en) |
| FR (1) | FR2359186A1 (en) |
| GB (1) | GB1590414A (en) |
| SE (1) | SE7708443L (en) |
| ZA (1) | ZA774349B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5502087A (en) | 1993-06-23 | 1996-03-26 | Dentsply Research & Development Corp. | Dental composition, prosthesis, and method for making dental prosthesis |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH652413A5 (en) * | 1978-09-20 | 1985-11-15 | Deltaglass Sa | PHOTOSETTING ADHESIVE COMPOSITION. |
| GB2055877B (en) * | 1979-08-06 | 1983-07-20 | Sony Corp | Magnetic recording media |
| JPS56122802A (en) * | 1980-03-03 | 1981-09-26 | Toyo Ink Mfg Co Ltd | Radiation-curable resin composition |
| NZ205989A (en) * | 1982-11-05 | 1987-04-30 | Deltaglass Sa | Radiation curable, urethane acrylate-containing fluid adhesive compositions and glass laminates |
| NL8401981A (en) * | 1984-06-22 | 1986-01-16 | Philips Nv | OPTICAL GLASS FIBER PROVIDED WITH A PLASTIC COATING AND METHOD FOR THE MANUFACTURE THEREOF. |
| JP4855028B2 (en) * | 2005-09-27 | 2012-01-18 | 富士フイルム株式会社 | Ink composition for inkjet recording, inkjet recording method, method for producing lithographic printing plate, and lithographic printing plate |
| JP4799981B2 (en) * | 2005-09-29 | 2011-10-26 | 富士フイルム株式会社 | Ink composition, inkjet recording method, lithographic printing plate production method, and lithographic printing plate |
| JP4896502B2 (en) | 2005-11-22 | 2012-03-14 | 富士フイルム株式会社 | Ink composition, inkjet recording method, lithographic printing plate production method, and lithographic printing plate |
| US10927269B2 (en) | 2017-06-27 | 2021-02-23 | Inx International Ink Co. | Energy cured heat activated ink jet adhesives for foiling applications |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3677920A (en) * | 1968-07-06 | 1972-07-18 | Asahi Chemical Ind | Photopolymerizable diisocyanate modified unsaturated polyester containing acrylic monomers |
| US3862021A (en) * | 1972-02-17 | 1975-01-21 | Asahi Chemical Ind | Polymerizable compositions and laminated articles bonded |
| DE2433908A1 (en) * | 1974-07-15 | 1976-02-05 | Basf Ag | RADIANT COATING COMPOUNDS |
-
1977
- 1977-07-19 ZA ZA00774349A patent/ZA774349B/en unknown
- 1977-07-21 DE DE19772733038 patent/DE2733038A1/en not_active Withdrawn
- 1977-07-21 AU AU27198/77A patent/AU516747B2/en not_active Expired
- 1977-07-21 SE SE7708443A patent/SE7708443L/en not_active Application Discontinuation
- 1977-07-22 FR FR7722543A patent/FR2359186A1/en active Granted
- 1977-07-22 GB GB30816/77A patent/GB1590414A/en not_active Expired
- 1977-07-22 CA CA283,373A patent/CA1102039A/en not_active Expired
- 1977-07-22 JP JP8822577A patent/JPS5313644A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5502087A (en) | 1993-06-23 | 1996-03-26 | Dentsply Research & Development Corp. | Dental composition, prosthesis, and method for making dental prosthesis |
| US5554665A (en) * | 1993-06-23 | 1996-09-10 | Dentsply Research & Development Corp. | Method and dispenser for making dental products |
Also Published As
| Publication number | Publication date |
|---|---|
| AU516747B2 (en) | 1981-06-18 |
| DE2733038A1 (en) | 1978-01-26 |
| JPS5313644A (en) | 1978-02-07 |
| FR2359186A1 (en) | 1978-02-17 |
| FR2359186B1 (en) | 1982-02-26 |
| ZA774349B (en) | 1978-06-28 |
| SE7708443L (en) | 1978-01-24 |
| AU2719877A (en) | 1979-01-25 |
| GB1590414A (en) | 1981-06-03 |
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