JPS6343413B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a molding material containing polystyrene as a main component. The present invention more particularly relates to a method for producing high-impact polystyrene with improved resistance to cracking under stress and/or corrosive chemicals. It is known that molded articles made from styrene polymers can crack under the stress of prolonged contact with chemicals that trigger corrosion phenomena. These chemicals include, in particular, oils, fats and blowing agents based on halogenated organics, such as Freon, for example. In practice, this corrosion is observed in edible oil containers and in the manufacture of high-impact polystyrene coolers. In the latter case, cracks will occur in the cooling chamber when polyurethane is foamed with a foaming agent such as Freon. The poor properties of high-impact polystyrene are compounded when Freon attack occurs when the chiller is already complete, requiring the chiller to be scrapped or uneconomically disassembled and reassembled. be. To solve this problem, the walls of the cooler that come into contact with the Freon were treated with acrylonitrile-butadiene.
Coating with a Freon-resistant film such as styrene terpolymer (ABS) has been proposed. However, the use of such protection systems significantly increases costs. It has also been proposed to substitute a portion of the above ABS with polyethylene film. Unfortunately, it is very difficult to achieve good adhesion between these two thermoplastic resins. It has also been proposed to add another rubber to increase crack resistance. Unfortunately, even with large amounts of rubber, no significant improvement is achieved. A method has now been discovered for producing molding materials which exhibit good properties against stress-induced cracking and/or against contact with corrosive chemicals. The present invention relates to a process for producing rubber-modified styrene exhibiting improved stress-crack resistance properties and good low-temperature properties, the process comprising subjecting a styrene solution of rubber to bulk polymerization, the rubber comprising: The proportion of 1,2-vinyl isomer is 10-12% and at least
An anionic polybutadiene having a high molecular weight equal to 300,000 and a viscosity of 140 centipoise or higher for a 5% styrene solution, the solution having a
% rubber, the polymerization is carried out by at least 0.08% by weight of the total weight of all components present in the solution;
alpha-methylstyrene dimer or n-dodecylmercaptan, tert-dodedocylmercaptan, diphenyl-1,3-butadiene, cis-diphenylcyclobutene, trans-diphenyl used in an amount of at most 0.3% by weight cyclohexane used in the presence of one selected from cyclobutene, methylphenylindane, diphenylcyclobutane and mixtures thereof and in an amount of at least 7% by weight of the total weight of all components present in the solution; It is characterized in that it is carried out in the presence of isopar or ethylbenzene. Another important feature of the process of the invention is that mono-, di- or triglycerides of stearic acid and mixtures thereof, polyethylene wax, polyethylene glycol, from 0.5 to 1% by weight of the total weight of all components present in the solution. The point is to use additives selected from additives containing functional groups and additives whose main component is silicone oil. The use of such additives facilitates the manufacture of the polymer. In the present invention, these additives are preferably added after polymerization, for example in an internal mixer. By using the method of the invention, not only good impact resistance is exhibited, but also, inter alia, stress-induced and/or
Alternatively, it is possible to obtain a polymer that is resistant to cracking due to contact with corrosive chemicals and exhibits good properties at low temperatures of 0° C. or lower. The combination of these properties makes it suitable for the construction of linings and door panels for refrigerators and refrigerators that are frequently cleaned with detergents, and for the production of decorations for kitchen utensils and chamber utensils.
The above polymers can be used without the need for additional protective measures. Resistance to corrosive chemicals also makes these polymers useful in the manufacture of seafood crates (especially those used for transporting fish), food packaging materials (especially those used for transporting fish),
This allows it to be used in the production of fatty foods (for fatty foods). The use of the method of the invention makes it possible to obtain polymers with a swelling index higher than 10. The swelling index is determined by dissolving the polymer obtained in toluene, then centrifuging and decanting the solution. The solid fraction obtained is weighed wet, then dried and reweighed. This swelling index is defined as a ratio as follows. Is = weight of wet gel/weight of dry gel. In fact, by this index it is possible to express the degree of crosslinking of the rubber. This swelling index should be considered as the reciprocal of the weight concentration; therefore, the higher the swelling index, the lower the degree of crosslinking of the rubber. The method of the invention gives polymers with gel contents higher than 30. This gel content represents the proportion of rubber, and is given as a value converted per gram of polymer according to the following relational expression. Cg (wt%) = dry weight of gel/test sample x 100 Another polymer obtained by the method of the present invention
One feature is that Kato, J.Electro.Micrs., 14 ,
The average diameter of the particles of the dispersed rubber phase observed by the electron microscopy method described in 19865 (20) is 8.
It is larger than a micron, and at most it is equal to 13 microns. This diameter is GRAIG
J.Polym.Sci.Polym.Chem., 15th edition, 433
(1977) and JAMES Polym.Eng.Sci., 8 ,
241 (1968).
These measuring methods make it possible to determine the average particle size and particle size distribution of elastomer masses dispersed in a polystyrene matrix. The most commonly used device for measuring the particle size and polydispersity of elastomeric globules dispersed in a styrene matrix is the "COULTER" counter sold by COULTRONICS. According to the method of the present invention, a polymer is produced which has the unique property of having a single glass transition temperature of the elastomeric phase. This glass transition is measured by a method known for measuring viscoelasticity, adjusted to a value of −80° C. or lower. The obtained polymer shows no secondary transition between -70°C and 0°C.
This glass transition measurement is performed using RHEOVIBRONDDV
- Performed using IIC viscoelasticity meter or METRAVIB viscoelasticity meter [Measurement method is NIBLSEN
Mechanical properties of Polymer and
Volume 2 of Composites [1974, Marcel Darker, New York, USA
Published by DERKER Inc.], also by J.BOYER
Macromol.Sci.Phys., B9 (2), 187 (1974)]. According to the invention, the glass transition spectrum of the rubber phase is spread over a specific temperature range that corresponds to the frequency-position characteristics of high-velocity impact frequencies. According to the invention, a molecular weight of 300,000 to 400,000;
A rubber consisting of anionic polybutadiene with a viscosity greater than 140 centipoise and less than 220 centipoise is used, and a styrene solution of this rubber is subjected to bulk polymerization. The above viscosity is a value measured by dissolving 5 parts by weight of rubber in 95 parts by weight of styrene. The use of rubbers with a viscosity higher than 220 centipoise results in solutions that are too viscous and difficult to handle and process on an industrial scale;
Using rubber lower than 140 centipoise results in too small particle size (much smaller than 10 microns)
This results in a polymer in small clumps with . In the present invention, the amount of rubber used is 7 to 10% by weight of the amount of styrene used. Use of amounts exceeding 10% results in polymers that are too elastic and, in particular, have fair mechanical properties but insufficient stiffness. In the present invention, anionic polybutadiene is understood to be a rubber produced by "anionic" polymerization. According to another feature of the invention, the polymerization is carried out using α-methylstyrene dimer or n-dodecyl mercaptan, tert-dodecyl mercaptan, diphenyl 1 , 3-butadiene, cis-diphenylcyclobutene, trans-diphenylcyclobutene,
It is carried out in the presence of one selected from methylphenylindane, diphenylcyclobutane or mixtures thereof. According to another important feature of the process of the invention, the polymerization is carried out in the presence of cyclohexane, Isopar or ethylbenzene, which is used in an amount equal to at least 7% by weight of the total weight of the solution. In the present invention, the amount of this solvent used varies depending on its properties, and is preferably 8% for ethylbenzene, 10% for cyclohexane, and 13% for isopar. Isopar is a commercially available product made of isoaliphatic hydrocarbons [Condensed Chemical Dictionary, published by Reinhold's Rose Company].
Chemical Dictionary). According to another important feature of the process of the invention, the polymerization comprises monostearic acid in an amount of 0.5 to 1% by weight, based on the total weight.
It is carried out in the presence of additives selected from di- or triglycerides or mixtures thereof, polyethylene waxes, additives containing polyethylene glycol functional groups, silicone oil-based additives. Di- or triglycerides of stearic acid are compounds with a melting point of about 60°C and a flash point higher than 150°C.
It is sold under the product name ATMOS 150 by AMERICA INC.). Polyethylene wax is a polymer wax sold by HULS. Polyethylene wax is a product having a dropping point of 70-80°C, a density of 0.86-0.88 and an average molecular weight of about 2500, and is sold, for example, by CdF CHIMIE. Silicone wax is a product that dissolves in most organic solvents and is sold by DOW CORNING under the name DOW CORNING 200 FLUID. The use of such additives facilitates the subsequent use of the resulting polymer and enhances the properties of the final product. These additives are added after polymerization using an internal mixer [e.g.
It is preferable to use a GK5 type mixer sold by PFLEIDERER. Adjustment of the melt flow index is achieved by the addition of 1 to 3% plasticizer, consisting in particular of liquid paraffin. This melt flow index measurement is performed according to ASTM standard D1238. In the present invention, polymerization is carried out by known methods. The autoclave used has a stirring device,
It is equipped with a heating device and a cooling device. All of the reaction reagents and additives used are chemicals used in bulk polymerization methods. 2,6-di-tert-butyl-p-cresol, 2,2-methylene-bis-
(4-methyl-6-tert-butylphenol), octadecyl 3-(3.5-di-tert-butyl-4-
hydroxyphenyl)-propionate, tri-
Antioxidants such as (2-methyl-4-hydroxy-5-tert-butylphenyl)-butane, triethylene glycol, bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionate, and phenol-based Mixtures of antioxidants and phosphates, benzoyl peroxide, di-peroxide
Polymerization initiators such as tert-butyl, cyclohexane peroxide, tert-butyl peroxyisopropyl carbonate, dicumyl peroxide, and tert-butyl perbenzoate are also used. All of these additives are used in small amounts. Antioxidants, whether used alone or in mixtures, should contain at most 0.5% of styrene.
The peroxide is used in an amount of at most 0.3% by weight of the styrene. Other commonly used additives such as paraffin oil,
It can be used in an amount equal to at most 5% by weight of styrene. The use of such compounds makes it possible to produce polymers that have both good heat resistance and good rheological properties, and also facilitates the use of the obtained polymers. Except for the peroxide, all the reactants are introduced into an autoclave and stirred and heated at a temperature of around 40° C. for 3 hours to dissolve the rubber into the other reactants. After this rubber dissolution step, the mixture is heated for about 8 hours to a temperature of 80-250°C. After polymerization, the obtained polymer is subjected to heat treatment, then devolatilized and coarsely crushed. The following examples are illustrative of the invention. All quantities are expressed in parts by weight. Example 1 In a bulk polymerization reactor equipped with a stirring device, a heating device, and a cooling device, 83.30 parts of styrene and 7.5 parts of styrene produced by the anionic polymerization method, 1,
2-vinyl isomer content is 10-12%, molecular weight is
350000, viscosity for 5% by weight styrene solution
190 centipoise polybutadiene rubber, 0.15 part α-methylstyrene dimer, 8 parts ethylbenzene, 1 part paraffin, and then octadecyl 3-(3.5-di-tert-butyl-4 0.05 part of an antioxidant consisting of -hydroxyphenyl)-propionate was added. The reaction mixture was then heated stepwise to a final temperature of 145° C. after 7 hours and 50 minutes. After this heating step 80 parts of solid were obtained which was heat treated for 1 hour and 50 minutes. 200 under reduced pressure of 730-740mmHg
After devolatilization, which consisted of subjecting the polymer to a heat treatment at a temperature of ˜240° C., the polymer was milled. The properties of the obtained polymers are summarized in the table below. - Vicat softening point was measured according to standard DIN53460.・Melt flow index conforms to ASTM standards
Measured by D1238. - Impact strength was measured using ASTM standard D256. - Gel content was calculated by stirring the obtained polymer in toluene under cooling and then centrifuging the mixture (this allows determination of the amount of gel insoluble in toluene). The dry mass of insoluble polymer was determined by previously treating the resulting gel under vacuum. The percentage of gel relative to the sample tested represents gel content. - The swelling index is equal to the mass ratio of gel to dry resin. - Particle size distribution was measured using the method of James, described above, and according to the technique of Cato, described above. - Tensile strength was measured according to standard DIN53455. Resistance to stress cracking and corrosion is standard AGK31
It was measured by This standard was developed by a research group consisting of chiller and thermoplastic resin manufacturers. This standard represents the residual elongation under a stress of 75 Kg/cm ² for injection molded specimens. This residual elongation should not be less than 75% if contact with halogenated hydrocarbons (Freons) is expected when the specimen is injection molded. This elongation should not be less than 50% when the specimens are produced by extrusion. Finally, this residual elongation should not be less than 40% when the specimen is compression molded. Example 2 81.08 parts styrene, 10 parts ethylbenzene,
Example 1 was repeated using 6.85 parts of the same polybutadiene rubber used in Example 1, 0.1 part of α-methylstyrene dimer, and 1.97 parts of paraffin oil. The properties of the obtained polymers are summarized in the table below. Example 3 80.98 parts of styrene and 0.2 parts of alpha instead of 0.1 parts
- Example 2 was repeated using methylstyrene dimer. The properties of the obtained polymers are summarized in the table below. Example 4 - 79.18 parts of styrene, - 11 parts of ethylbenzene, - 0.15 parts of α-methylstyrene dimer, - 3.38 parts of paraffin oil, - 5.8 parts of fully anionic polybutadiene rubber, - 0.042 parts of Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-
Example 1 was repeated using propionate. The properties of the obtained polymers are summarized in the table below. Example 5 - 82.9 parts of styrene, - 7.5 parts of ethylbenzene, - 0.10 parts of α-methylstyrene dimer, - 2.3 parts of paraffin oil, - 1 part of glycerol monostearate and glycerol distearate. Mixture: Example 1 was repeated using 6.2 parts of polybutadiene. The properties of the obtained polymers are summarized in the table below. Example 6 - 78.06 parts of styrene, - 6.82 parts of rubber, - 13 parts of Isopar, - 0.15 parts of α-methylstyrene dimer, - 1.97 parts of paraffin oil, - 0.5 parts of glycerol monostearate. Example 1 was repeated using the mixture with glycerol distearate. The properties of the obtained polymers are summarized in the table below. Example 7 - 79.18 parts of styrene, - 0.042 parts of an antioxidant sold under the name IRGANOX 1076, - 3.83 parts of paraffin oil, - 5.8 parts of anionic polybutadiene, - 11 parts of ethylbenzene, - 0.10 parts of α-methylstyrene dimer, - 0.042 parts of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-
Example 1 was repeated using propionate. The properties of the obtained polymers are summarized in the table below. Example 8 - 83.69 parts of styrene, - 7.5 parts of ethylbenzene, - 0.083 parts of α-methylstyrene dimer, - 1.91 parts of paraffin oil, - 0.5 parts with an average molecular weight of 2500 and a viscosity at 120°C 60~100 centipoise, density 0.86, dropping point 70~
Example 1 was repeated using polyethylene wax at 80°C, and 6.82 parts of anionic polybutadiene. The properties of the obtained polymers are summarized in the table below. Example 9 A polymer was prepared from the following ingredients. - 83.69 parts of styrene, - 7.5 parts of ethylbenzene, - 6.82 parts obtained by anionic polymerization method, 10-12
% 1,2-vinyl isomer content, a molecular weight of 350,000 and a viscosity of 190 centipoise in 5% by weight styrene solution, - 0.083 parts of α-methylstyrene dimer, - 1.91 parts of paraffin. Oil, 0.5 part of a synthetic wax with a melting point of 140°C, sold under the name NOPCOWAX 22DS by DIA-MOND SHAMROCK. The properties of the obtained polymers are summarized in the table below. Example 10 Example 9 was repeated, substituting the synthetic rubber with a portion of wax sold under the name POLYWAX by Fuls. The properties of the obtained polymers are summarized in the table below. Example 11 Example 9 was repeated by substituting 1 part polyethylene wax having an average molecular weight of 2500, a viscosity of 60-100 centipoise (at 120°C), a density of 0.86, and a dropping point of 70-80°C. The properties of the obtained polymers are summarized in the table below. Example 12 Example 9 Substituting 0.5 parts of wax with 1 part of silicone oil sold by Dow Corning Company under the name Dow Corning 200 Fluid
repeated. The properties of the obtained polymers are summarized in the table below. Example 13 Example 9 was repeated substituting 0.5 part of a solid polymer wax "800" sold by Fluss Co. for the silicone oil. The properties of the obtained polymers are summarized in the table below. Example 14 A polymer of the invention was prepared using the following ingredients. - 81.03 parts of styrene, - 10 parts of ethylbenzene, - 6.85 parts of the same polybutadiene rubber as used in Example 1, - 0.10 parts of α-methylstyrene dimer, - 1.97 parts of paraffin oil, - 0.05 part of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-
Antioxidants based on propionate, - 0.5 parts of a mixture of glycerol monostearate and glycerol distearate. The properties of the obtained polymers are summarized in the table below. Example 15 Polymers of the invention were prepared using the following ingredients: - 81.03 parts of styrene, - 10 parts of ethylbenzene, - 6.85 parts of the same polybutadiene as used in Example 1, - 0.10 parts of α-methylstyrene dimer, - 1.97 parts of paraffin oil, - 0.5 parts Part of silicone oil. The properties of the obtained polymers are summarized in the table below. Example 16 α-methylstyrene dimer was converted into diphenyl 1,
3-butadiene, cis-diphenylcyclobutene,
Example 1 was repeated substituting a mixture consisting of trans-diphenylcyclobutene, methylphenylindane, and diphenylcyclobutane. The properties of the obtained polymers are summarized in the table below. Comparative Example 1 A polymer was obtained using the following amounts of reactants. - 83.69 parts of styrene, - 7.5 parts of ethylbenzene, - 6.82 parts of anionic polybutadiene (containing 10-12% 1,2-vinyl isomer) and Ziegler polybutadiene (as a substitute for a single anionic polybutadiene). 97% 1,4-cis
0.073 parts of α-methylstyrene dimer, 1.91 parts of paraffin oil. The properties of the obtained polymers are summarized in the table below. Comparative Example 2 A polymer was prepared from the following components: 83.70 parts of styrene, 7.5 parts of ethylbenzene, 0.073 parts of α-methylstyrene dimer, 1.91 parts of paraffin oil, 6.82 parts of 11% 1 , 2-vinyl isomer, anionic polybutadiene having a solution viscosity of 95 centipoise and an average molecular weight of 273,000. The properties of the obtained polymers are summarized in the table below. The following abbreviations have been used in the following table: TS: Tensile strength M.: Modulus BS: Breaking stress YS: Yield stress EB: Elongation at break RE: Residual elongation ES: Extrusion molded test piece CS: Cast molded test piece・Oil resistance is indicated by the product name LIVIO. Measurements were made using commercially available olive oil. - The dimensions of the extruded test piece were 200 x 20 x 2 mm. Resistance to stress cracking and corrosion was expressed as residual elongation at break as a percentage defined by the following formula. Residual elongation rate (%) = Tensile elongation at break after contact with Freon or oil / Initial tensile elongation at break × 100

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Claims (1)

[Scope of Claims] 1. A method for producing rubber-modified styrene exhibiting improved stress cracking resistance and good low-temperature properties, comprising the step of subjecting a styrene solution of rubber to bulk polymerization, the rubber comprising: 1 , the proportion of 2-vinyl isomer is 10~
12%, a high molecular weight equal to at least 300,000, and a viscosity of at least 140 centipoise with respect to a 5% styrene solution, said solution containing from 7 to 10% by weight of rubber; At least 0.08% and at most 0.3% by weight of the total weight of all components present in the solution
α-methylstyrene dimer or n-dodecylmercaptan, tert-dodecylmercaptan, diphenyl 1,3-butadiene, used in an amount of
in the presence of one selected from cis-diphenylcyclobutene, trans-diphenylcyclobutene, methylphenylindane, diphenylcyclobutane or mixtures thereof, and of the total weight of all components present in the solution. Mono-, di- or triglycerides of stearic acid and their The process is carried out using additives selected from mixtures, polyethylene waxes, additives containing polyethylene glycol functional groups and additives based on silicone oils.