CA1177189A - Thermoplastic molding materials - Google Patents
Thermoplastic molding materialsInfo
- Publication number
- CA1177189A CA1177189A CA000386154A CA386154A CA1177189A CA 1177189 A CA1177189 A CA 1177189A CA 000386154 A CA000386154 A CA 000386154A CA 386154 A CA386154 A CA 386154A CA 1177189 A CA1177189 A CA 1177189A
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- CA
- Canada
- Prior art keywords
- weight
- resistant
- particles
- diameter
- impact
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
- C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
- C08L71/08—Polyethers derived from hydroxy compounds or from their metallic derivatives
- C08L71/10—Polyethers derived from hydroxy compounds or from their metallic derivatives from phenols
- C08L71/12—Polyphenylene oxides
- C08L71/123—Polyphenylene oxides not modified by chemical after-treatment
Abstract
Abstract of the Disclosure: Thermoplastic molding mater-ials based on styrene polymers which have been made impact-resistant and on polyphenylene ethers, wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 micron, and wherein the proportion of particles which have a diameter or less than 0.6 micron is not less than 40% by weight and the proportion of particles which have a diameter of from 0.6 to 3 microns is less than 3% by weight.
Description
7~9 Thermoplastic molding materials The pr~sent invention relates to thermoplastic molding materials based on styrene polymers which have been made impact-resistant, and on polyphenylene ethers.
Thermoplastic materials which are suitable for the production of moldings and which contain styrene polymers which have been made impact-resistant and polyphenylene ethers are disclosed, for example, in U.S. patents 3,383,435, 4,128,602 and 4,128,603. Such molding materials can be used for the ; 10 production of moldings which exhibit better heat-distortion resistance than those made from styrene polymers which have been made impact-resistant but have not been blended with polyphenylene ethers. The physical properties of such molding materials are generally satisfactory, but it has been found that the molding materials have poor flow and that moldings produced from them have inadequate mechanical properties, s~ch as inadequate rigidity.
It would be advantageous to have thermoplastic molding materials, based on styrene polymers which have been made - 20 impact-resistant andon polyphenylene ethers,which materials can be converted to moldings having improved properties.
The present invention provides a thermoplastic molding material either (i) based on the styrene polymers which have been made impact-resistant and on polyphenylene ethers, wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 micron and wherein the proportion of particles which have a diameter of less than 0.6 micron is not less than 40~ by weight and the proportion of particles which have a diameter of from 0.6 to 3 microns is less than 3~ by weight or ~ C,~ ~' (ii) comprising from 20 to 80% by weight of a styrene polymer which has been made impact-resistant and from 80 to 20% by weight of a polyphenylene eth~r, wherein from 95 to 85% by weight of the particles of the soft component have a diameter of from 0.2 to 0.5 micron and from 15 to 5%
by weight of the particles of the soft component have a diameter of from 4 to 7 microns.
As indicated above the present invention provides molding materials wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 ~m (micron) and wherein the proportion of particles which have a diameter of _ ~ ' ~:~'7~ 39
Thermoplastic materials which are suitable for the production of moldings and which contain styrene polymers which have been made impact-resistant and polyphenylene ethers are disclosed, for example, in U.S. patents 3,383,435, 4,128,602 and 4,128,603. Such molding materials can be used for the ; 10 production of moldings which exhibit better heat-distortion resistance than those made from styrene polymers which have been made impact-resistant but have not been blended with polyphenylene ethers. The physical properties of such molding materials are generally satisfactory, but it has been found that the molding materials have poor flow and that moldings produced from them have inadequate mechanical properties, s~ch as inadequate rigidity.
It would be advantageous to have thermoplastic molding materials, based on styrene polymers which have been made - 20 impact-resistant andon polyphenylene ethers,which materials can be converted to moldings having improved properties.
The present invention provides a thermoplastic molding material either (i) based on the styrene polymers which have been made impact-resistant and on polyphenylene ethers, wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 micron and wherein the proportion of particles which have a diameter of less than 0.6 micron is not less than 40~ by weight and the proportion of particles which have a diameter of from 0.6 to 3 microns is less than 3~ by weight or ~ C,~ ~' (ii) comprising from 20 to 80% by weight of a styrene polymer which has been made impact-resistant and from 80 to 20% by weight of a polyphenylene eth~r, wherein from 95 to 85% by weight of the particles of the soft component have a diameter of from 0.2 to 0.5 micron and from 15 to 5%
by weight of the particles of the soft component have a diameter of from 4 to 7 microns.
As indicated above the present invention provides molding materials wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 ~m (micron) and wherein the proportion of particles which have a diameter of _ ~ ' ~:~'7~ 39
- 2 - O.Z. 0050/03a677 less than 0.6 ~m is not less than 40% by weight and the proportion of particles which have a diameter of from 0.6 to 3 ~m is less than 3% by weight.
For the purposes of the invention, the molding materials are usually mixtures which can, by thermoplastic processing within certain tempera-ture ranges, be converted to moldings or to rods, tubes or sheets. The molding materials can be in the form of granules or powder, or be premolded by tableting.
They can also be in the form of sheets or webs.
The impact-resistant styrene polymers contained in the molding materials can be prepared by any desired method, provided that it results in the above particle size distributions. However, it is also possible to blend impact-resistant styrene polymers in which the soft components have different particle sizes. The styrene polymers contained in the molding materials according to the invention can be obtained, for example, by -mixing polymers having a particular particle size of the soft component with polymers in which the particle size of the soft component is different. For example, gO parts by weight of a polymer which has a mean particle size of the soft component o~ 0.5 ~m can be blended with ~0 parts by weight of a polymer which has a mean particle size of the soft component of 6 ~m.
Particularly suitable thermoplastic molding
For the purposes of the invention, the molding materials are usually mixtures which can, by thermoplastic processing within certain tempera-ture ranges, be converted to moldings or to rods, tubes or sheets. The molding materials can be in the form of granules or powder, or be premolded by tableting.
They can also be in the form of sheets or webs.
The impact-resistant styrene polymers contained in the molding materials can be prepared by any desired method, provided that it results in the above particle size distributions. However, it is also possible to blend impact-resistant styrene polymers in which the soft components have different particle sizes. The styrene polymers contained in the molding materials according to the invention can be obtained, for example, by -mixing polymers having a particular particle size of the soft component with polymers in which the particle size of the soft component is different. For example, gO parts by weight of a polymer which has a mean particle size of the soft component o~ 0.5 ~m can be blended with ~0 parts by weight of a polymer which has a mean particle size of the soft component of 6 ~m.
Particularly suitable thermoplastic molding
- 3 - O.Z. OOS0/034677 materials are those in which from 9S to 85% by weight of the particles of the soft component have a dia-meter of from 0.2 to 0.5 /um and 15 to 5% by weight of the particles have a diameter of from 4 to 7 /um.
The thermoplastic molding materials can contain the impact-resistant styrene polymer and the polyphenylene ether in any desired proportion, ~for example from 5 to 90% by weight of the styrene polymer and from 95 to 10% by weight of the polyphenylene ether. Materials which contain from 20 to 80% by weight of impact-resistant styrene polymer and from 80 to 20% by weight of polypheny-lene ether are particularly suitable for the production of moldings.
The most commonly used methods of preparation of impact-resistant styrene polymers are mass polymeriza-tion or solution polymerization, as described, for example, in U.S. Patent 2,694,692, and mass-suspension polymerization, as described, for example, in U.S.
Patent 2,862,906. Of course, other methods can also be employed, provided they result in the particle size combination described above.
Particularly suitable monovinyl-aromatic compounds are styrene and nuclear-alkylated and sidechain-alkylated styrenes, though preferably styrene alone is used.
The rubbers used in the preparation of the impact-resistant polystyrene are the natural or synthetic ~'7'~
The thermoplastic molding materials can contain the impact-resistant styrene polymer and the polyphenylene ether in any desired proportion, ~for example from 5 to 90% by weight of the styrene polymer and from 95 to 10% by weight of the polyphenylene ether. Materials which contain from 20 to 80% by weight of impact-resistant styrene polymer and from 80 to 20% by weight of polypheny-lene ether are particularly suitable for the production of moldings.
The most commonly used methods of preparation of impact-resistant styrene polymers are mass polymeriza-tion or solution polymerization, as described, for example, in U.S. Patent 2,694,692, and mass-suspension polymerization, as described, for example, in U.S.
Patent 2,862,906. Of course, other methods can also be employed, provided they result in the particle size combination described above.
Particularly suitable monovinyl-aromatic compounds are styrene and nuclear-alkylated and sidechain-alkylated styrenes, though preferably styrene alone is used.
The rubbers used in the preparation of the impact-resistant polystyrene are the natural or synthetic ~'7'~
- 4 - O.Z. 0050/034677 rubbers conventionally employed for making styrene polymers impact-resistant. Suitable rubbers, for the purposes of the invention~ are not only natural rubber but also, for example, polybutadiene, polyisoprene and copolymers of butadiene and/or isoprene with styrene and other comonomers, provided such copolymers have a glass transition temperature of below -20C. Butadiene polymers having a 1,4-cis content of from 25 to 98 % are particularly suitable.
The irnpact-resistant polymers having the pattern of properties required according to the invention are prepared by polymerizing the monovinyl-aromatic compounds in the presence of the rubber. As mentioned, this polymeri-za-tion is as a rule carried out in a conventional manner, as a mass polymerization, solution polymerization or aqueous dispersion polymerization, the rubber first being dissolved in the polymerizable monomer and this starting solution then being polymerized.
In solution polymerization, up to a maximum f 50 per cent by weight based on monovinyl-aromatic compounds employed, of an inert diluent may be added to the above starting solution. Examples of suitable inert diluents are aromatic hydrocarbons or mixtures of such hydrocarbons; toluene, ethylbenzene, the xylenes and mixtures of these compounds are preferred.
In aqueous dispersion polymerization, as a rule no solvent is added; in a particularly advantageous embodiment, the solution of the rubber in the monomers is mass-prepolymerized to a conversion of about 30%
- ~ ~'7'i~8~
" .
_ 5 _ o~Z~ 0050/0346~7 under the action o~ shearing forces, after which the reaction mixture is suspended in water and the polymeriza-tion then taken to completion. In general, this process is started by adding oil-soluble initiators which decom-pose to give free radicals, such as benzoyl peroxide, dicumyl peroxide, di-tert.-butyl peroxide, azo-diisobutyro-nitrile or the like, or combinations of these, but the prepolymerization can also be started thermally.
Suitable suspending agents are the conventional water-soluble, high molecular weight co`mpounds, eg. methyl-cellulose, hydroxypropylcellulose, polyvinyl alcohol, partially hydrolyzed polyvinyl acetates and the like, and inorganic dispersants, for example barium sulphate.
The suspending agents are in general employed in amounts of from 0.1 to 5% by weight, based on the organic phase.
Mass polymerization or solution polymerization is as a rule carried out at.from 50 to 250C, preferably from 100 to 200~C. The polymerization batch must be thoroughly stirred, at least in the first stage of the polymerization, ie. up to conversions of the monovinyl-aromatic compounds of 45% by weight or less. All the above polymerization processes are adequately known and are described in detail in the literature~ A summary is given by Amos, Polym. Engng. Sci., 14 (1974), No.l, 1 - 11, and in U.S. Patents 2,694,692 and 2,862,906, to which reference may be made for further details.
-For the purposes of the invention, the soft component is defined as the part of the impact-resistant polymer which is insoluble in toluene at room temperature '7'7~
- 6 - O.Z. 0050/03a~77 (2SC), minus any pigments present. Accordingly, the soft component corresponds to the gel component of the product.
The soft component in general has a heterogeneous structure; the component as a rule forms in the course of the process of preparation and its amount, and degree of sub-division, are affected by the process conditions.
As is known, the solution of the rubber in the monovinyl-aromatic monomer separates, immediately after the start o~ the polymerization reaction, into two phases, of which one, namely a solution of the rubber in the mono-meric vinyl-aromatic, initially forms the continuous phase, whilst the other, namely a solution o~ the poly-vinyl-aromatic in its own monomer, remains suspended in droplets in the continuous phase. With increasing conversion, the amount of the second phase increases at the expense of the first, and with consumption of the monomers. At a certain stage, a change in phase continuity occurs, and droplets of rubber solution form in the polyvinyl-aromatic solution; however, these droplets, in turn, contain trapped smaller droplets of what is at that stage the continùous phase.
Alongside this phenomenon, a grafting reaction takes place, in which chemical bonds between the rubber molecules and the polyvinyl-aromatics are formed, with the production of a graft copolymer of the two components.
This phenomenon is known and is described in detail by, for example, Fischer, Angew. Makromol. Chem. 33 (1973), 35 - 74.
7'7~89 _ 7 _ O.Z. 0050/034677 The soft component is taken to include both the grafted-on polyvinyl-aromatic and the polyvinyl-aromatic mechanically trapped in the rubber particles.
~hen the mass has completely polymerized, the resulting product comprises a heterogeneous soft component which consists of grafted rubber particles containing trapped matrix material (polyvinyl-aromatic), and which is embedded in a hard matrix of the polyvinyl-aromatic.
The greater the amount of the trapped matrix material, the greater is the amount of the soft component, for a given rubber content.
Accordingly, the amount of the soft component not only depends on -the amount of rubber employed but also on how the process is conducted, especially before and during phase inversion. The individual measures are specific to the process and are known to a skilled worker (see, for example, Freeguard, Brit. Polym. J.
6 (1974), 203 - 22~; Wagner and Robeson, Rubber Chem.
Techn. 4~ (1970), 1129 et seq.).
In order to arrive at impact-resistant thermo-plastic ~.aterials having the pattern of properties according to the invention, the amount of rubber which, before polymerization, is dissolved in the monomer -to prepare the starting solution is chosen, as a function of the final conversion during polymerization, so that the content of soft component in the resulting product, namely a polymer of the monovinyl-aromatic compounds which has been made impact-resistant, is not less than 20% by weight, preferably 25% by weight or more, based ~ . .
- 8 - O.Z. 0050/03~677 on the said impact-resistant polymer. The upper limit of the content of soft component is about 50 - 60%
by weight, and is imposed by the requirement that the polyvinyl-aromatic should form the continuous phase.
For the thermoplastic molding materials according to the invention, a soft -component content of 25 - 35 per cent by weight, based on the polymer which has been made impact-resistant, has proved particularly advantageous. The rubber content of the said polymer is then in general from 2 to 20% By weight, preferably from 5 to 15% by weight.
As is explained above and is indeed adequately known, the po]ymer of the monovinyl-aromatic compounds, which has been made impact-resistant, consists of a homogeneous continuous phase (matrix) of the polymer of the monovinyl-aromatic compound, in which the rubber particles of the soft component are embedded as the disperse phase, the rubber particles having been partially crosslinked and been grafted, to a greater or lesser degree, with the monovinyl-aromatic compounds during the polymerization.
The mean particle size of the disperse soft component can be determined by, for example, counting and evaluating electron microphotographs of thin layers of the impact-resistant polymers (cf. ~.Lenz, Zeitschrift f~r Wiss. Mikroskopie, 63 (1956), 50-56).
In the above process, the particle size of the disperse soft - component phase is adjusted, in a conventional manner, during polymerization of the mono-_ g _ o.Z. 0050/034677vinyl-aromatic compounds, by suitable choice of the speed ofstirring_ in the first stage of the polymerization, ie. up to a monomer conversion of 45% or less. The particle size of the disperse soft - component phase is the greater, the lower the stirrer speed and accord-ingly the lower the shearing stress. The relation between stirring speed and size and distribution of the rubber particles in the resulting impact-resistant polymer is described, for example, by Freeguard, loc.cit., to whose paper reference may be madè for further details.
The particular stirring speed re~ulred to achieve the desired particle size of the disperse soft-component phase depends, inter alia, on the details of the particu-lar apparatus and is known to a skilled wor~er or can be determined by a few simple experimerts.
The mean particle size (weight average) of the disperse soft -component phase was determined from electron microphotographs of thin layers, by counting and averaging the particles belonging to the same size category (constant interval width~. The cu~ulative distribution curve was determined from the volume of the particles (3rd power of the apparent diameter) within the intervals. The equivalent diameter can then be read off the abscissa as the value corresponding to the 50% ordinate value. The mean diameters quoted are the mean of at least 5,000 particles.
The polyphenylene ethers used are ortho-disubstitu~ed polyphenylene oxides, ~ ~'7:~39 - lO - o.Z. 0050/03~677 the ether oxygen of one unit being bonded to the benzene nucleus of the next unit, and at least S0 units being thus linked. The polyphenylene ethers can contain hydrogen, halogen, hydrocarbon radicals ~ree rrom ~-tert.-h~drogen, halohydrocarbon radicals, phenyl radicals and hydrocarbon-oxy radicals in the ortho-position to the oxygen. Accordingly, suitable materials include poly-(2,6-dichloro-1,4-phenylene)-ether, poly-(2,6-diphenyl-1,4-phen`ylene)-ether, poly-(2,6-dimethoxy-1,4-phenylene)-ether, poly-(2,6-dimethyl-1,4-phenylene)-ether and poly-~2,6-dibromo-1,4-phenylene)-ether, amongst which poly-(2,6-dimethyl-1,4-phenylene)-ether, more especially having an intrinsic viscosity of from 0.45 to 0.65 dl/g (measured in chloroform at 30C)~is preferred.
The polyphenylene ethers can be prepared from the phenols, for example in the presence of complexing agents such as copper bromide and sec.-dibutylamine.
The mixtures of the impact-resistant styrene polymers and polyphenylene ethers can furthermore contain additives such as pigments, dyes, fillers, flameproofing agents, other compatible polymers, antistatic agents, - antioxidants and lubricants.
The thermoplastic molding materials according to the invention are prepared in a conventional manner on equipment which permits mixing the components homogene-ously, such as kneaders, extruders or roll mills. In addition to high flo~3 the molding materials 71~3~3 - 11 - O.Z. 0050/03a677 also have other good properties, such as highrigid-ity and other good mechanical proper~ies.
EXAMPLES AND COMPARATIVE EXPERIMENTS
I. An impact-resistant polystyrene having a mean particle size of the soft component of ' 0.6 ~m is obtained by using the following recipe:
A solution consisting of 1,560 g of styrene, 240 g of a butadiene/styrene block copolymer having a gradual transition between the blocks ([~J = 1.74 - [dl/g], measured in toluene at 25; block polystyrene = 31.0%; [~ = 0.364 rdl/g], measured in toluene at 25; total styrene content = 41.6%), 1.6 g of t-dodecyl-mercaptan, 2.2 g of octadecyl 3-(3't5'-di-tert.-butyl-4-hydroxyphenyl)-propionate and 1.7 g of dicumyl peroxide was prepolymerized, in a 5 liter stirred kettle with blade stirrer, at 110C inter~al temperature and a stirrer speed of l50 rpm, until the solids content was 43.8% by weight.
1,800 ml of water containing 9.0 g of polyvinyl-pyrrolidone of K value 90, and 1.8 g of Na4P207, were then added and the stirrer speed was increased to 300 rpm. The polymerization was then taken to ~99% conversion of styrene by a final treatment of S hours at 120C
and 5 hours at 140C.
II. An impact-resistant polystyrene having a mean particle size of the soft component of aoout 6 ~m was prepared by the following method:
A solution consisting of 1,283 g of styrene, 112 g of polybutadiene (about 9% by weight of 1,2-vinyl content), 1.5 g of t-dodecylmercaptan, 1.5 g of octadecyl - 12 - O.Z. 0050/03a677 3-(3',5'-di-tert.-butyl-4'-hydroxyphenyl)-propionate and 1.5 g of dicumyl peroxide was prepolymerized, in a 4 liter stirred kettle with blade stirrer, at 110C
internal temperature and a stirrer speed of 150 rpm, until the solids content was 25.4% by weight. 1,800 ml of water containing 9 g of polyvinylpyrrolidone of K value 90~ and 1.8 g of Na4P2 07j were then added and the stirrer speed was increased to 300 rpm. The polymerization was then taken to ~99% conversion of styrene by a final treatment of 3 hours at 110C, 3 hours at 120C and 4 hours at 140C.
III. An impact-resistant polystyrene having a mean particle size of the soft component of 2.5 ~m was prepared by the following method:
A solution consisting of 1,283 g of styrene, 112 g of polybutadiene (about 9% by weight of 1,2-vinyl content), 1.5 g of t-dodecylmercaptan, 1.5 g of octadecyl 3-(3',5'-di-tert.-butyl-4'-hydroxyphenyl)-propionate and 1.5 g of dicumyl peroxide was prepolymerized, in a 4 liter stirred kettle with blade stirrer, at 110C
internal temperature and a stirrer speed of 300 rpm, until the solids content was 25.4% by weight. 1,800 ml of water containing 9 g of polyvinylpyrrolidone of K value 90)and 1.8 g of Na4P207~were then added and the stirrer speed was increased to 400 rpm. The polymeri-zation was then taken to ~99% conversion of styrene by a final treatment of 3 hours at 110C, 3 hours at 120C and 4 hours at 140C.
~'7~
- 13 - O.Z. 0050Jo3a677 The desired mean particle sizes and particle size distributions were obtained by blending the impact-resistant polystyrenes resulting ~rom methods I, II
and III.
The parts by weight of impact-resistant polystyrene and of poly-(2,6-dimethyl-1,4-phenylene)-ether shown in the Table, together with, in each case, 0.8 part by weight of tris-(nonylphenyl)-phosphite and 1.5 parts by weight of polyethylene, were melted, homogenized, mixed and granulated on a twin-screw extruder operated at 2803C. The poly-(2,6-dimethyl-1,4-phenylene)-ether had an intrinsic viscosity of 0.48 dl/g.
Test specimens were prepared from the mixtures on an injection molding machine at 280C.
The breaking energy was determined according to DIN 53,443, page 1, at 23C, and the modulus of elasticity on test specimens o~ size 4 x 10 x 150 mm according to DIN 53,457. The flow was assessed in terms of the melt index, according to DIN 53,735.
The results are summarized in the Table.
~ - 14 - O.Z. 0050/03a~677 ~:~ .
~ .
,1 ~ ~ O o O o o O o o ~ ~ ~ ~ Ln ~ ~o (o ~: ~ Z c~ C~
a:a) ~
~ ~ oa~ u~ D 0 ~ ~ ~ o ~ ~ ~ ~ n u~
~ U~ Ln L~ ~n ~ ~, ~3 ~ ~ ~ ~ ~ ~ ~ ~t o ~ D O O ~ O' U~ o ~o ,, ~S u~ F~ ~ O ~n O o o 3 S~ '~ O a~ J) 0 ~0 ~ r~l ~ ~V S
'O~ g ~ 0 ~ 0 C~J ~ O U~ ~ ' .
S~ C~ 0 ~ ~ ~
~ 0 IS~ 7 In U~ n E ~ ~ 3 ~ D ,~
o~:: ' ~-~
u~
s~ ~ ~ ~ ~ ¢ p~ o ~ ~ So X ~ O -~
.
The irnpact-resistant polymers having the pattern of properties required according to the invention are prepared by polymerizing the monovinyl-aromatic compounds in the presence of the rubber. As mentioned, this polymeri-za-tion is as a rule carried out in a conventional manner, as a mass polymerization, solution polymerization or aqueous dispersion polymerization, the rubber first being dissolved in the polymerizable monomer and this starting solution then being polymerized.
In solution polymerization, up to a maximum f 50 per cent by weight based on monovinyl-aromatic compounds employed, of an inert diluent may be added to the above starting solution. Examples of suitable inert diluents are aromatic hydrocarbons or mixtures of such hydrocarbons; toluene, ethylbenzene, the xylenes and mixtures of these compounds are preferred.
In aqueous dispersion polymerization, as a rule no solvent is added; in a particularly advantageous embodiment, the solution of the rubber in the monomers is mass-prepolymerized to a conversion of about 30%
- ~ ~'7'i~8~
" .
_ 5 _ o~Z~ 0050/0346~7 under the action o~ shearing forces, after which the reaction mixture is suspended in water and the polymeriza-tion then taken to completion. In general, this process is started by adding oil-soluble initiators which decom-pose to give free radicals, such as benzoyl peroxide, dicumyl peroxide, di-tert.-butyl peroxide, azo-diisobutyro-nitrile or the like, or combinations of these, but the prepolymerization can also be started thermally.
Suitable suspending agents are the conventional water-soluble, high molecular weight co`mpounds, eg. methyl-cellulose, hydroxypropylcellulose, polyvinyl alcohol, partially hydrolyzed polyvinyl acetates and the like, and inorganic dispersants, for example barium sulphate.
The suspending agents are in general employed in amounts of from 0.1 to 5% by weight, based on the organic phase.
Mass polymerization or solution polymerization is as a rule carried out at.from 50 to 250C, preferably from 100 to 200~C. The polymerization batch must be thoroughly stirred, at least in the first stage of the polymerization, ie. up to conversions of the monovinyl-aromatic compounds of 45% by weight or less. All the above polymerization processes are adequately known and are described in detail in the literature~ A summary is given by Amos, Polym. Engng. Sci., 14 (1974), No.l, 1 - 11, and in U.S. Patents 2,694,692 and 2,862,906, to which reference may be made for further details.
-For the purposes of the invention, the soft component is defined as the part of the impact-resistant polymer which is insoluble in toluene at room temperature '7'7~
- 6 - O.Z. 0050/03a~77 (2SC), minus any pigments present. Accordingly, the soft component corresponds to the gel component of the product.
The soft component in general has a heterogeneous structure; the component as a rule forms in the course of the process of preparation and its amount, and degree of sub-division, are affected by the process conditions.
As is known, the solution of the rubber in the monovinyl-aromatic monomer separates, immediately after the start o~ the polymerization reaction, into two phases, of which one, namely a solution of the rubber in the mono-meric vinyl-aromatic, initially forms the continuous phase, whilst the other, namely a solution o~ the poly-vinyl-aromatic in its own monomer, remains suspended in droplets in the continuous phase. With increasing conversion, the amount of the second phase increases at the expense of the first, and with consumption of the monomers. At a certain stage, a change in phase continuity occurs, and droplets of rubber solution form in the polyvinyl-aromatic solution; however, these droplets, in turn, contain trapped smaller droplets of what is at that stage the continùous phase.
Alongside this phenomenon, a grafting reaction takes place, in which chemical bonds between the rubber molecules and the polyvinyl-aromatics are formed, with the production of a graft copolymer of the two components.
This phenomenon is known and is described in detail by, for example, Fischer, Angew. Makromol. Chem. 33 (1973), 35 - 74.
7'7~89 _ 7 _ O.Z. 0050/034677 The soft component is taken to include both the grafted-on polyvinyl-aromatic and the polyvinyl-aromatic mechanically trapped in the rubber particles.
~hen the mass has completely polymerized, the resulting product comprises a heterogeneous soft component which consists of grafted rubber particles containing trapped matrix material (polyvinyl-aromatic), and which is embedded in a hard matrix of the polyvinyl-aromatic.
The greater the amount of the trapped matrix material, the greater is the amount of the soft component, for a given rubber content.
Accordingly, the amount of the soft component not only depends on -the amount of rubber employed but also on how the process is conducted, especially before and during phase inversion. The individual measures are specific to the process and are known to a skilled worker (see, for example, Freeguard, Brit. Polym. J.
6 (1974), 203 - 22~; Wagner and Robeson, Rubber Chem.
Techn. 4~ (1970), 1129 et seq.).
In order to arrive at impact-resistant thermo-plastic ~.aterials having the pattern of properties according to the invention, the amount of rubber which, before polymerization, is dissolved in the monomer -to prepare the starting solution is chosen, as a function of the final conversion during polymerization, so that the content of soft component in the resulting product, namely a polymer of the monovinyl-aromatic compounds which has been made impact-resistant, is not less than 20% by weight, preferably 25% by weight or more, based ~ . .
- 8 - O.Z. 0050/03~677 on the said impact-resistant polymer. The upper limit of the content of soft component is about 50 - 60%
by weight, and is imposed by the requirement that the polyvinyl-aromatic should form the continuous phase.
For the thermoplastic molding materials according to the invention, a soft -component content of 25 - 35 per cent by weight, based on the polymer which has been made impact-resistant, has proved particularly advantageous. The rubber content of the said polymer is then in general from 2 to 20% By weight, preferably from 5 to 15% by weight.
As is explained above and is indeed adequately known, the po]ymer of the monovinyl-aromatic compounds, which has been made impact-resistant, consists of a homogeneous continuous phase (matrix) of the polymer of the monovinyl-aromatic compound, in which the rubber particles of the soft component are embedded as the disperse phase, the rubber particles having been partially crosslinked and been grafted, to a greater or lesser degree, with the monovinyl-aromatic compounds during the polymerization.
The mean particle size of the disperse soft component can be determined by, for example, counting and evaluating electron microphotographs of thin layers of the impact-resistant polymers (cf. ~.Lenz, Zeitschrift f~r Wiss. Mikroskopie, 63 (1956), 50-56).
In the above process, the particle size of the disperse soft - component phase is adjusted, in a conventional manner, during polymerization of the mono-_ g _ o.Z. 0050/034677vinyl-aromatic compounds, by suitable choice of the speed ofstirring_ in the first stage of the polymerization, ie. up to a monomer conversion of 45% or less. The particle size of the disperse soft - component phase is the greater, the lower the stirrer speed and accord-ingly the lower the shearing stress. The relation between stirring speed and size and distribution of the rubber particles in the resulting impact-resistant polymer is described, for example, by Freeguard, loc.cit., to whose paper reference may be madè for further details.
The particular stirring speed re~ulred to achieve the desired particle size of the disperse soft-component phase depends, inter alia, on the details of the particu-lar apparatus and is known to a skilled wor~er or can be determined by a few simple experimerts.
The mean particle size (weight average) of the disperse soft -component phase was determined from electron microphotographs of thin layers, by counting and averaging the particles belonging to the same size category (constant interval width~. The cu~ulative distribution curve was determined from the volume of the particles (3rd power of the apparent diameter) within the intervals. The equivalent diameter can then be read off the abscissa as the value corresponding to the 50% ordinate value. The mean diameters quoted are the mean of at least 5,000 particles.
The polyphenylene ethers used are ortho-disubstitu~ed polyphenylene oxides, ~ ~'7:~39 - lO - o.Z. 0050/03~677 the ether oxygen of one unit being bonded to the benzene nucleus of the next unit, and at least S0 units being thus linked. The polyphenylene ethers can contain hydrogen, halogen, hydrocarbon radicals ~ree rrom ~-tert.-h~drogen, halohydrocarbon radicals, phenyl radicals and hydrocarbon-oxy radicals in the ortho-position to the oxygen. Accordingly, suitable materials include poly-(2,6-dichloro-1,4-phenylene)-ether, poly-(2,6-diphenyl-1,4-phen`ylene)-ether, poly-(2,6-dimethoxy-1,4-phenylene)-ether, poly-(2,6-dimethyl-1,4-phenylene)-ether and poly-~2,6-dibromo-1,4-phenylene)-ether, amongst which poly-(2,6-dimethyl-1,4-phenylene)-ether, more especially having an intrinsic viscosity of from 0.45 to 0.65 dl/g (measured in chloroform at 30C)~is preferred.
The polyphenylene ethers can be prepared from the phenols, for example in the presence of complexing agents such as copper bromide and sec.-dibutylamine.
The mixtures of the impact-resistant styrene polymers and polyphenylene ethers can furthermore contain additives such as pigments, dyes, fillers, flameproofing agents, other compatible polymers, antistatic agents, - antioxidants and lubricants.
The thermoplastic molding materials according to the invention are prepared in a conventional manner on equipment which permits mixing the components homogene-ously, such as kneaders, extruders or roll mills. In addition to high flo~3 the molding materials 71~3~3 - 11 - O.Z. 0050/03a677 also have other good properties, such as highrigid-ity and other good mechanical proper~ies.
EXAMPLES AND COMPARATIVE EXPERIMENTS
I. An impact-resistant polystyrene having a mean particle size of the soft component of ' 0.6 ~m is obtained by using the following recipe:
A solution consisting of 1,560 g of styrene, 240 g of a butadiene/styrene block copolymer having a gradual transition between the blocks ([~J = 1.74 - [dl/g], measured in toluene at 25; block polystyrene = 31.0%; [~ = 0.364 rdl/g], measured in toluene at 25; total styrene content = 41.6%), 1.6 g of t-dodecyl-mercaptan, 2.2 g of octadecyl 3-(3't5'-di-tert.-butyl-4-hydroxyphenyl)-propionate and 1.7 g of dicumyl peroxide was prepolymerized, in a 5 liter stirred kettle with blade stirrer, at 110C inter~al temperature and a stirrer speed of l50 rpm, until the solids content was 43.8% by weight.
1,800 ml of water containing 9.0 g of polyvinyl-pyrrolidone of K value 90, and 1.8 g of Na4P207, were then added and the stirrer speed was increased to 300 rpm. The polymerization was then taken to ~99% conversion of styrene by a final treatment of S hours at 120C
and 5 hours at 140C.
II. An impact-resistant polystyrene having a mean particle size of the soft component of aoout 6 ~m was prepared by the following method:
A solution consisting of 1,283 g of styrene, 112 g of polybutadiene (about 9% by weight of 1,2-vinyl content), 1.5 g of t-dodecylmercaptan, 1.5 g of octadecyl - 12 - O.Z. 0050/03a677 3-(3',5'-di-tert.-butyl-4'-hydroxyphenyl)-propionate and 1.5 g of dicumyl peroxide was prepolymerized, in a 4 liter stirred kettle with blade stirrer, at 110C
internal temperature and a stirrer speed of 150 rpm, until the solids content was 25.4% by weight. 1,800 ml of water containing 9 g of polyvinylpyrrolidone of K value 90~ and 1.8 g of Na4P2 07j were then added and the stirrer speed was increased to 300 rpm. The polymerization was then taken to ~99% conversion of styrene by a final treatment of 3 hours at 110C, 3 hours at 120C and 4 hours at 140C.
III. An impact-resistant polystyrene having a mean particle size of the soft component of 2.5 ~m was prepared by the following method:
A solution consisting of 1,283 g of styrene, 112 g of polybutadiene (about 9% by weight of 1,2-vinyl content), 1.5 g of t-dodecylmercaptan, 1.5 g of octadecyl 3-(3',5'-di-tert.-butyl-4'-hydroxyphenyl)-propionate and 1.5 g of dicumyl peroxide was prepolymerized, in a 4 liter stirred kettle with blade stirrer, at 110C
internal temperature and a stirrer speed of 300 rpm, until the solids content was 25.4% by weight. 1,800 ml of water containing 9 g of polyvinylpyrrolidone of K value 90)and 1.8 g of Na4P207~were then added and the stirrer speed was increased to 400 rpm. The polymeri-zation was then taken to ~99% conversion of styrene by a final treatment of 3 hours at 110C, 3 hours at 120C and 4 hours at 140C.
~'7~
- 13 - O.Z. 0050Jo3a677 The desired mean particle sizes and particle size distributions were obtained by blending the impact-resistant polystyrenes resulting ~rom methods I, II
and III.
The parts by weight of impact-resistant polystyrene and of poly-(2,6-dimethyl-1,4-phenylene)-ether shown in the Table, together with, in each case, 0.8 part by weight of tris-(nonylphenyl)-phosphite and 1.5 parts by weight of polyethylene, were melted, homogenized, mixed and granulated on a twin-screw extruder operated at 2803C. The poly-(2,6-dimethyl-1,4-phenylene)-ether had an intrinsic viscosity of 0.48 dl/g.
Test specimens were prepared from the mixtures on an injection molding machine at 280C.
The breaking energy was determined according to DIN 53,443, page 1, at 23C, and the modulus of elasticity on test specimens o~ size 4 x 10 x 150 mm according to DIN 53,457. The flow was assessed in terms of the melt index, according to DIN 53,735.
The results are summarized in the Table.
~ - 14 - O.Z. 0050/03a~677 ~:~ .
~ .
,1 ~ ~ O o O o o O o o ~ ~ ~ ~ Ln ~ ~o (o ~: ~ Z c~ C~
a:a) ~
~ ~ oa~ u~ D 0 ~ ~ ~ o ~ ~ ~ ~ n u~
~ U~ Ln L~ ~n ~ ~, ~3 ~ ~ ~ ~ ~ ~ ~ ~t o ~ D O O ~ O' U~ o ~o ,, ~S u~ F~ ~ O ~n O o o 3 S~ '~ O a~ J) 0 ~0 ~ r~l ~ ~V S
'O~ g ~ 0 ~ 0 C~J ~ O U~ ~ ' .
S~ C~ 0 ~ ~ ~
~ 0 IS~ 7 In U~ n E ~ ~ 3 ~ D ,~
o~:: ' ~-~
u~
s~ ~ ~ ~ ~ ¢ p~ o ~ ~ So X ~ O -~
.
Claims (5)
1. A thermoplastic molding material based on styrene polymers which have been made impact-resistant and on polyphenylene ethers, wherein the particles of the soft compo-nent of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 micron and wherein the proportion of particles which have a diameter of less than 0.6 micron is not less than 40 % by weight and the porportion of particles which have a diameter of from 0.6 to 3 microns is less than 3 % by weight.
2. A thermoplastic molding material comprising from 20 to 80 % by weight of a styrene polymer which has been made impact-resistant and from 80 to 20 % by weight of a poly-phenylene ether, wherein from 95 to 85 % by weight of the particles of the soft component have a diameter of from 0.2 to 0.5 micron and from 15 to 5 % by weight of the particles of the soft component have a diameter of from 4 to 7 microns.
3. A thermoplastic molding material as claimed in claim 2, wherein the content of soft component is from 25 to 35 per cent by weight, based on polymer which has been made impact-resistant.
4. A thermoplastic molding material as claimed in claim 2, wherein the rubber content of the polymer which has been made impact-resistant is from 5 to 15 % by weight.
5. A thermoplastic molding material either (i) based on the styrene polymers which have been made impact-resistant and on polyphenylene ethers , wherein the particles of the soft component of the styrene polymer which has been made impact-resistant have a mean diameter of more than 1 micron and wherein the proportion of particles which have a diameter of less than 0.6 micron is not less than 40% by weight and the proportion of particles which have a diameter of from 0.6 to 3 microns is less than 3% by weight or (ii) comprising from 20 to 80% by weight of a styrene polymer which has been made impact-resistant and from 80 to 20% by weight of a polyphenylene ether , wherein from 95 to 85% by weight of the particles of the soft component have a diameter of from 0.2 to 0.5 micron and from 15 to 5%
by weight of the particles of the soft component have a diameter of from 4 to 7 microns.
by weight of the particles of the soft component have a diameter of from 4 to 7 microns.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803035560 DE3035560A1 (en) | 1980-09-20 | 1980-09-20 | THERMOPLASTIC MOLDS |
| DEP3035560.3 | 1980-09-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1177189A true CA1177189A (en) | 1984-10-30 |
Family
ID=6112458
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386154A Expired CA1177189A (en) | 1980-09-20 | 1981-09-17 | Thermoplastic molding materials |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4412037A (en) |
| EP (1) | EP0048400B2 (en) |
| JP (1) | JPS5785841A (en) |
| CA (1) | CA1177189A (en) |
| DE (2) | DE3035560A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3113953A1 (en) * | 1981-04-07 | 1982-10-21 | Basf Ag, 6700 Ludwigshafen | IMPACT THERMOPLASTIC MOLDS |
| US4824887A (en) * | 1986-12-19 | 1989-04-25 | General Electric Company | High impact rubber modified polystyrene and polyphenylene ether resins containing the same |
| DE3736852A1 (en) * | 1987-10-30 | 1989-05-11 | Basf Ag | THERMOPLASTIC MOLDS BASED ON POLYPHENYLENE ETHER |
| CA2009053C (en) * | 1989-02-03 | 1999-09-28 | Isao Sasaki | Impact-resistant resin |
| JP2612396B2 (en) * | 1992-04-20 | 1997-05-21 | 旭化成工業株式会社 | Method for manufacturing resin molded body |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1125620A (en) * | 1965-01-06 | 1968-08-28 | Gen Electric | Improvements in polymeric blends |
| CA927540A (en) * | 1970-04-24 | 1973-05-29 | Katchman Arthur | Polyphenylene ether composition |
| US4128602A (en) * | 1970-04-24 | 1978-12-05 | General Electric Company | Polyphenylene ether compositions containing rubber modified polystyrene |
| JPS5420537B1 (en) * | 1971-04-30 | 1979-07-24 | ||
| US3787532A (en) * | 1971-12-03 | 1974-01-22 | Gen Electric | Polyphenylene ether compositions |
| GB1422208A (en) * | 1972-08-23 | 1976-01-21 | Gen Electric | Polyphenylene ether compositions apparatus for continuous hydrogenation |
| CA1032687A (en) * | 1972-12-29 | 1978-06-06 | Arthur Katchman | Polyphenylene ether compositions |
| US4128603A (en) * | 1974-07-18 | 1978-12-05 | General Electric Company | Compositions comprising polyphenylene ether and rubber modified polystyrene |
| US4097549A (en) * | 1975-12-29 | 1978-06-27 | Monsanto Company | Polymer polyblend composition |
-
1980
- 1980-09-20 DE DE19803035560 patent/DE3035560A1/en not_active Withdrawn
-
1981
- 1981-09-10 DE DE8181107118T patent/DE3169996D1/en not_active Expired
- 1981-09-10 EP EP81107118A patent/EP0048400B2/en not_active Expired - Lifetime
- 1981-09-14 US US06/302,040 patent/US4412037A/en not_active Expired - Fee Related
- 1981-09-17 CA CA000386154A patent/CA1177189A/en not_active Expired
- 1981-09-18 JP JP56146438A patent/JPS5785841A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0048400A1 (en) | 1982-03-31 |
| DE3035560A1 (en) | 1982-05-06 |
| EP0048400B2 (en) | 1991-07-24 |
| EP0048400B1 (en) | 1985-04-17 |
| DE3169996D1 (en) | 1985-05-23 |
| US4412037A (en) | 1983-10-25 |
| JPS5785841A (en) | 1982-05-28 |
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