JPS60158212A - Manufacture of impact-resistant polystyrene having good characteristics against corrosive chemicals - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 and 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 foaming polyurethane 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, it has been proposed to coat the chiller walls in contact with Freon with a Freon-resistant film such as acrylonitrile-butadiene-styrene terpolymer (8BS). Then, the cost increases by a large amount.Also, to the above B
It has also been proposed to substitute a portion of S with a 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 2-vinyl isomer is 10-1
2%, a high molecular weight at least equal to 300,000, and a viscosity for a 5% styrene solution of at least 140 centipoise;
The solution contains 7-10% by weight of rubber, and the polymerization is carried out in an amount of at least O, O8 of the total weight of all components present in the solution.
α-methylsterene dimer or n-dodecyl mercaptan, used in an amount of at most 0.3% by weight;
tert-dodecyl mercaptan, diphenyl 1.3
-bucdiene, cis-diphenylcyclobutene, tr
cyclohexane in the presence of one selected from ans-diphenylcyclobutene, methylphenylindan, 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; The method 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 The point is to use additives selected from additives containing glycol functional groups and additives based on silicone oils. 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, it not only shows good impact resistance but also, inter alia, is less susceptible to cracking due to stress and/or due to contact with corrosive chemicals and shows good properties at low temperatures below 0°C. It is possible to obtain polymers.

The combination of these properties provides an additional protective treatment for the construction of linings and door coverings in refrigerators and freezers that are frequently cleaned with cleaning agents, and for the production of decorations for kitchen and bathroom utensils. The above polymers can be used without the need for application. Resistance to corrosive chemicals also allows the polymers to be used in the production of seafood crates (especially those used for transporting fish), food packaging materials (especially those for fatty foods). There is.

The use of the method of the invention makes it possible to obtain polymers with a higher swelling index than IO. 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 the ratio:

In fact, this index makes it 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 Ig of polymer according to the following relational expression.

Another feature of the polymers obtained by the method of the invention is that Kato, J., formerly electro0Micros,
'.

14, 19865'(20>) that the average diameter of the particles of the dispersed rubber phase is less than 8 microns and equal to at most 13 microns. is GRAIG's J, Polym, Sci, Polym, Chem,
, 15th edition, 433 (1977) and JAMBS Polym, Bng, Sci, 8.241 (196B
) is measured by the method described in . These measurement 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 equipment for measuring the particle size and polydispersity of elastomeric globules dispersed in a styrene matrix is the C0IILTRON Ic
This is the "CDULT13R" counter sold by eight companies.

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 less. The obtained polymer shows no secondary transition between -70°C and 0°C. do not have.

Measurement of the conogas transition is performed using R11BOV[BRON
D D V-TIC viscoelasticity meter or MBTR8VI viscoelasticity meter [measurement method is NIBLSBN
Mechanical Pro-parties o
f Polymer and Composites, Volume 2 [1974, Marcel, New York, USA]
Published by Marcel DBRKBRLnc], also :J, BOYBR's Macro-mo
l, Sci, Phys,, B 9 (2).

1g? - (1974)]. According to the present invention, the glass transition spectrum of the rubber phase is spread over a specific temperature range corresponding to the frequency-position characteristics of high-velocity impact frequencies.

According to the invention, a rubber consisting of anionic polybutadiene with a molecular weight of 300.000 to 400.000, a viscosity higher than 140 centipoise and lower than 220 centipoise is used, and a styrene solution of this rubber is subjected to bulk polymerization (= J.The above viscosity is 95% by weight of 5 parts by weight of rubber.
This value is measured after dissolving in parts by weight of styrene.

Using a rubber with a viscosity higher than 220 centipoise will result in a solution that is too viscous and difficult to handle and process on an industrial scale, whereas using a rubber with a viscosity lower than 140 centipoise will result in a solution that is too small (10 microns). This results in a clumped polymer having a size (much smaller).

In the present invention, the amount of rubber used is 7 to 10% by weight of the amount of styrene used. Amounts exceeding 10% result in polymers which 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 comprises α-methylstyrene dimer or n-dodecyl mercaptan, t
ert-dodecylmercaptan, diphenyl 1.3-
butadiene, cls-diphenylcyclobutene, tra
It is carried out in the presence of one selected from ns-diphenylcyclobutene, methylphenylindan, 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, lsopar 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, preferably 8% for ethylbenzene and 10% for cyclohexane.
, is 13% in isopar.

Isopar is a commercially available product made of isoaliphatic hydrocarbons [Condensed Chemical Dictionary (Re'1nhold) published by 1'1ose Company].
1 Dictionary)]. According to another important feature of the process of the invention, the polymerization is carried out at 0% by total weight.
．． of additives selected from mono-, di- or triglycerides of stearic acid or mixtures thereof, polyethylene waxes, additives containing polyethylene glycol functional groups, silicone oil-based additives in an amount of 5 to 1% by weight. carried out in the presence of Stearic acid di- or triglyceride is a compound with a melting point of about 60"C and a flash point higher than 150"C, such as ICI America, Inc. (
It is sold under the trade name Atmos (8TMO8) 150 by IcI AMBRI [:A INC,).

Polyethylene wax is a polymeric wax sold by Fluss (ltlLs). Polyethylene wax has a dropping point of 70-80°C, 0.86-0.88
The product has a density of about 2,500 and an average molecular weight of about 2,500.
For example, Save-F CHIMIB (CdP CHIMIB)
It is sold by the company. Silicone wax is a product that dissolves in most organic solvents and is available from Dow Corning (
The name Dow Corning (001 (CORNING) 2007 Le f-F (
FLtllD) and sold separately. The use of such additives facilitates the subsequent use of the resulting polymer,
The properties of the final product are enhanced. These additives are added after polymerization using an internal mixer [e.g.
1! It is preferable to use a GK5 type mixer sold by IBRNBR-PFLBI'DBRBR'.

Adjustment of the melt flow index is achieved by the addition of 1 to 3% plasticizer, in particular consisting of liquid paraffin.

This melt flow index measurement is performed according to ASTM standard D123B.

In the present invention, polymerization is carried out by known methods. The autoclave used is equipped with a stirring device, a heating device, and a cooling device. All of the reaction reagents and additives used are chemicals used in bulk polymerization methods. 2,
6-tert-butyl-p-cresol, 2.2-
Methylene-bis-(4-methyl-6-tert-butylphenol), octadecyl 3-(3,5-di-te
rt-butyl-4-hydroxyphenyl)-propionate, tri(2-methyl-4-hydroxy-5-te
rt-butylphenyl)-phthane, antioxidants such as triethylene glycol bis-3=(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionate, mixtures of phenolic antioxidants and phosphates, Polymerization initiators such as benzoyl peroxide, di-tert-butyl peroxide, cyclohexane peroxide, tert-butylperoxyisopropyl carbonate, dicumyl peroxide, and tert-butyl perbenzoate are also used. All of these additives are used in small amounts. Whether used alone,
When used as a mixture, the antioxidant is at most 0.5% of the styrene and the peroxide is at most 0.5% of the styrene.
Used at 3% by weight. Other conventional additives such as paraffin oil can also be used in amounts 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 to a temperature of 80-250° C. for about 8 hours. After polymerization, the obtained polymer is subjected to heat treatment, then devolatilized and coarsely crushed.

The following examples are illustrative of the invention. All amounts 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; - 7.5 parts of 1,2-vinyl isomer produced by an anionic polymerization method. body content 10-12%, molecular weight 350.00
Polybutadiene rubber having a viscosity of 190 centipoise in a 0.5% by weight styrene solution; 0.15 parts α-methylstyrene dimer; 8 parts ethylbenzene; 1 part paraffin; , 0.05 parts of an antioxidant consisting of octadecyl 3-(3,5-tert-butyl-4-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 heated at 50°C for 1 hour.
Heat treated. 730-740mm 11g under reduced pressure 2
o.

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 D r N 53460.

・Melt flow index is ASTM ffl rating D1
238.

- Impact strength was measured using ASTM standard D256.

- Gel content is determined by stirring the obtained polymer in toluene under cooling and then centrifuging the mixture (thereby
(allowing 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 by the technique of Caddo, described above.

- Tensile strength was measured according to standard D I N 53455.

Resistance to stress cracking and corrosion was measured according to standard AGK31. This standard was developed by a research group consisting of chiller and thermoplastic resin manufacturers. This standard specifies 75 kg/kg for injection molded specimens.
It represents the residual elongation rate under stress of cffl. This residual elongation rate is 75% if contact with halogenated hydrocarbons (Freon) is expected when the specimen is injection molded.
Must not be less than 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, 6
．． 85 parts of the same polybutadiene rubber used in Example 1, 0.1 part of α-methylstyrene dimer, 1
．． Example 1 was repeated using 97 parts of paraffin oil.

The properties of the obtained polymers are summarized in the table below.

Example 3 Example 2 was repeated using 80, 98 parts of styrene and 0.2 part of α-methylstyrene dimer instead of 0.1 part.

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, - 3.83 parts
Example 1 using 1 part paraffin oil, 5.8 parts fully anionic polybutadiene rubber, and 0.042 parts octadecyl 3-(3,5-di-tert-phthyl-4-hydroxyphenyl)-propionate. repeated.

The properties of the obtained polymers are summarized in the table below.

Example 5 ・82.9 parts of styrene, 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, 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, - 197 parts of paraffin oil, - o, 5s Example 1 was repeated using a mixture of glycerol monostearate and 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 IRG8N 1076,
- 3.83 parts of paraffin oil, - 5.8 parts of anionic polybutadiene, - 11 parts of ethylbenzene, - 0.10 parts of α-methylstyrene dimer, - 0.04 parts
2 parts of octadecyl 3-(3,5-di-tart-'
Example 1 was repeated using f-thyl-4-hydroxyphenyl)-propionate.

The properties of the obtained polymers are summarized in the table below.

Example 8 ・83.69 parts of styrene, 5 parts of ethylbenzene, ・0.083 parts of α-methylstyrene dimer, ・1.9
1 part paraffin oil; 0.5 part polyethylene wax with an average molecular weight of 2.500.1 viscosity at 20°C of 60-100 centipoise, density 0.86, dropping point of 70-80°C; 6.82 Example I was repeated using the same 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, 5 parts of ethylbenzene, ・6.82 parts of 10 to 12 parts obtained by anionic polymerization method
Polybutadiene, having a rubinyl content of 1,2% to 0.083%, a molecular weight of 350.000, and a viscosity of 190 centipoise when made into a 5% by weight styrene solution.
α-methylstyrene dimer of 1. Paraffin oil of the old capital, 0.5 parts of Diamond Shamlota (DJA
- From MOIII SIIAM ROCK) company name NOPCDIllAX 22D
A synthetic wax with a melting point of 140°C, sold as S.

The properties of the obtained polymers are summarized in the table below.

Example 10 Synthetic rubber was manufactured by Fluss under the name Polywax (P River, Y
Example 9 was repeated, substituting 1 part of wax sold as (W8).

The properties of the obtained polymers are summarized in the table below.

Example 11 Nopkowask 22DS was prepared with an average molecular weight of 2.500, a viscosity of 60 to ioo centipoise (120°C), and a density of 0.8.
6. Example 9 was repeated substituting 1 part polyethylene wax with a dropping point of 70-80°C.

The properties of the obtained polymers are summarized in the table below.

Example 12 0.5 parts of wax was added to 1 part of wax sold by Dow Corning under the name Dow Corning 200 Fluid.
Example 9 was repeated, substituting the same silicone oil.

The properties of the obtained polymers are summarized in the table below.

Example 13 Example 9 was repeated, substituting 0.5 parts of a solid polymeric wax "800" sold by Fluss Co. for the silicone oil.

The properties of the obtained polymers are summarized in the table below.

Example 14 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 rubber used in Example 1, - 0.10 parts of α-methylstyrene dimer,・1.97
1 part paraffin oil, 0.05 part octadecyl 3-(3,5-di-t)
Antioxidant based on ert-butyl-4-hydroxyphenyl)-flobionate: 0.5 part 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 present 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 part of alpha-methylstyrene dimer; - 1. 97
1 part paraffin oil, 0.5 part 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, trans
-diphenylcyclobutene, methylphenylindan,
Example 1 was repeated substituting a mixture composed of diphenylcyclobutane.

The properties of the obtained polymers are summarized in the table below.

Comparative example 1 Polymers were obtained using the following amounts of reactants:

- 83.69 parts of styrene, 5 parts of ethylbenzene, - 6.82 parts of anionic polybutadiene (10-12%) as a substitute for a single anionic polybutadiene.
(containing 1,2-vinyl isomer) and Ziegler polybutadiene (containing 97% 1,4-cis isomer).
-50 mixture of polybutadiene, 0.073 parts of α-methylstyrene dimer, 1.91
paraffin oil.

The properties of the obtained polymers are summarized in the table below.

Comparative example 2 A polymer was prepared from the following ingredients:

・83.70 parts of styrene, 5 parts of ethylbenzene, 0.073 parts of α-methylstyrene dimer, ・1.9
1 part paraffin oil; 6.82 parts of an anionic polybutadiene containing 11% of the 1,2-vinyl isomer and 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:

T, S, : Tensile strength M, : Modulus B, S, : Breaking stress Y, S, : Yield stress E, B, : Elongation at break R, E, : Residual elongation E, S, : Extrusion molding test Pieces C, S - Cast molded test pieces - Oil resistance was measured using olive oil commercially available under the trade name LIVIO.

・The dimensions of the extrusion test piece are 200 x 20 x 2 mm.
Met.

Resistance to stress cracking and corrosion was expressed as a percentage defined by the following formula as residual elongation at break.

Claims (1)

Claims: 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 to bulk polymerization, the rubber comprising: 1. The proportion of 2-vinyl isomer is 10-12%
is an anionic polybutadiene having a high molecular weight of at least equal to 300.000 and a viscosity of 140 centipoise or higher for a 5% styrene solution, the solution containing from 7 to 10% by weight of rubber, At least 0.08 of the total weight of all components present in the solution
.alpha.-methylstyrene dimer or n-totysylmercaptan, tert-dodecylmercaptan, diphenyl used in an amount of at most 0.3% by weight; 1.
3-butadiene, cis-diphenylcyclobutene, t
cyclohexane in the presence of one selected from rans-diphenylcyclobutene, methylphenylindan, diphenylcyclobutane or mixtures thereof and in an amount of at least 7% by weight of the total weight of all components present in the solution; and mono-, di- or triglycerides of stearic acid and mixtures thereof, polyethylene wax, polyethylene glycol functionality in the presence of The above method is characterized in that it is carried out using an additive selected from additives containing groups and additives whose main component is silicone oil.