KR960016625B1 - Styrene resin composition of high nitrile with heat stability - Google Patents

Abstract

a first step wherein 50 to 90 wt.parts a monomer mixture of 50 to 80 wt.% a vinyl cyanide, 20 to 50 wt.% an aromatic vinyl compound, 5 wt.% or less of an unsaturated carboxylic acid or esters thereof or a vinyl acetate and 15 wt.% or less of a vinyl amide compound are graft-polymerized in the presence of 10 to 50 wt.parts a rubber latex and also in the presence of 0.001 to 2.0 wt. parts of a polymerization inhibitor to prepare a graft polymer(A); a second step wherein 50 to 80 wt.% a vinyl cyanide, 20 to 50 wt.% an aromatic vinyl compound and 5 wt.% or less of an unsaturated carboxylic acid or esters thereof are polymerized, while adding 2.0 wt.parts or less of a polymerization inhibitor to the mixture, to prepare a copolymer(B); or a third step wherein 100 wt.parts a styrene resin provided by mixing a copolymer(C) consisting of 25 to 40 wt.% a vinyl cyanide and 60 to 75 wt.% an aromatic vinyl compound are used in combination with 3-6 wt.parts a lubricant of one or more than two elements selected from paraffin wax, polyethylene wax, polypropylene wax, ethylenebis steamide, stearate ester, barium stearate or calcium stearate to form the composition wherein the rubber content in the composition falls within the range of 10 to 30 wt.%.

Description

Styrene-based resin composition with excellent thermal stability with high nitrile content

The present invention relates to a high nitrile-containing styrene resin composition having good HCFC resistance (hydrechlorofluorocarbon resistance), excellent vacuum resistance, excellent thermal stability, and no color change.

In general, ABS resin and impact resistant polystyrene (HIPS) have been used as an inner phase for refrigerators, and a polyurethane foam layer is used as a heat insulating material between the inner side of the refrigerator and iron plates outside the refrigerator.

However, CFC (chlorofluorocarbon) has been used as a foaming agent in polyurethane foaming, and CFC is an environmental pollutant that destroys the earth's ozone layer.

Therefore, the CFC is being replaced by HCFC (hydrochlorofluorocar bon) which is less harmful to the ozone layer.

However, when HCFC is used as a blowing agent, cracks and erosion of ABS resins generally occur, and thus, they cannot be used as a refrigerator inner phase.

Therefore, when used for this purpose, a resin having excellent HCFC resistance should be used. Generally, the higher the nitrile content, the better the resistance to chemicals is known in US Patent No. 3426102.

However, the higher the nitrile content, the lower the impact strength, the less the fluidity, the more difficult the machining, and due to the deterioration of the thermal stability, the color change during the extrusion process is severely followed.

In addition, ABS resin has a large difference in physical properties between MD (Mashine direction) and TD (Transverse direction), where MD and TD are referred to as the machine direction when the sheet is extruded, and the direction perpendicular to this is TD. Says.

As described above, when the elongation deviation of MD and TD increases to about 50% or more, the deformation state of the sheet due to biaxial stretching during vacuum forming is not uniform, which may cause uneven product thickness in the final product. It may also cause mold failure, such as tearing of the product by local thinning.

In addition, the high nitrile styrene resin forms polychromin-like chromophores due to the influence of temperature and shear stress during extrusion, which leads to severe color discoloration, and the rearrangement of the polymer in the MD direction results in the MD and TD directions. Due to the significant difference in properties, molding failure may occur.

Therefore, the present inventors have diligently studied, and the color problem by inhibiting the production of polyimine by inhibiting the production of a series of acrylonitrile units using a polymerization inhibitor when the graft polymerization of a high nitrile content (Graft polymerization) Improved latex stability and thermal stability by adding vinylamide, and minimizing the effect of shear stress by using appropriate amount of lubricant during processing to prevent chromophore formation to improve thermal stability better and without changing processing conditions As a result of minimizing the difference in physical properties between MD and TD, the inventors have invented a high-flowing resin (composition) such as HCFC resistance, vacuum forming, thermal safety, and impact strength.

That is, the present invention is 50 to 80% by weight of vinyl cyanide compound, 20 to 50% by weight of aromatic vinyl compound and up to 5% by weight of unsaturated carboxylic acid, esters thereof or vinyl acetate in the presence of 10 to 50 parts by weight of rubber latex, When graft polymerization using 50-90 parts by weight of 15% by weight or less of vinylamide compound, 50 to 80% by weight of graft copolymer (A) and vinyl cyanide compound prepared using 0.001 to 2.0 parts by weight of polymerization inhibitor 25 to 40% by weight of a copolymer (B) or vinyl cyanide compound prepared using 2.0 parts by weight or less of polymerization inhibition when polymerizing from 50% by weight of an aromatic vinyl compound to 5% by weight of unsaturated carboxylic acid or esters thereof. And a copolymer (C) consisting of 60 to 75% by weight of an aromatic vinyl compound to 100 parts by weight of styrene resin having a rubber content of about 10 to 30% by weight. Polyesters such as ethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, ethylene bissteamide, stearate ester and complex ester, magnesium stearate, barium The present invention relates to a high nitrile-containing styrene resin composition composed of 2 to 6 parts by weight of a lubricant in combination of one or two or more selected from metal salts of stearic acid, such as stearate and calcium stearate.

Hereinafter, the present invention will be described in detail.

In the present invention, a small-diameter rubber latex (A) having a gel content of 70 to 90% and a particle size of 0.05 to 0.15 mu and agglomerated with an acid or polymerized by a general emulsion polymerization method prepared by an emulsion polymerization method A large diameter rubber latex (B) having a particle diameter of 0.20 to 0.50 µ is used.

50 to 80% by weight of a vinyl cyanide compound in the presence of 10 to 50 parts by weight of the latex rubber latex (A) and 30 to 50 parts by weight of the latex rubber (B) using 70 to 100% by weight of the large diameter rubber latex (B). Graft polymerization is performed using 50 to 90 parts by weight of 50% by weight of aromatic vinyl compound, 5% by weight or less of unsaturated carboxylic acid, esters thereof or vinyl acetate, and 15% by weight or less of vinyl amide compound.

At this time, using a water-soluble polymerization inhibitor 0.001-2.0 parts by weight to prepare a graft copolymer.

These graft copolymers may be used alone, and in addition, 50 to 80% by weight of vinyl cyanide compound, 20 to 50% by weight of aromatic vinyl compound and 5% by weight or less of unsaturated carboxylic acid or esters thereof 2.0 parts by weight of polymerization inhibitor It is mixed with a copolymer prepared using the following to use a rubber content of about 10 to 30% by weight to prepare a high nitrile content styrene resin having a low YI (yellowness index) value.

The YI value is obtained by mixing the graft copolymer with a SAN copolymer made of a bulk polymerization of 25 to 40% by weight of a vinyl cyanide compound and 60 to 75% by weight of an aromatic vinyl compound to obtain a rubber content of 10 to 30% by weight. This greatly improved styrene resin is produced.

The high nitrile styrene resin prepared in the present invention can withstand a mixture of HCFC 141b and a mixture of HCFC 141b and HCFC 123 (However, when using a SAN copolymer of a bulk polymerization of 25 to 40% by weight of vinyl cyanide compound, HCFC 141b It is well tolerated, but cracking may occur if the HCFC 123 content in the mixture of HCFC 141b and HCFC 123 exceeds 40% by weight.)

In the present invention, the styrene-based resin production method is divided into a small diameter rubber latex, a sound collecting process, and a graft copolymerization process.

① Manufacturing and flocculation process of small diameter rubber latex

When the small-diameter rubber latex of 0.05 to 0.15μ is prepared by a reaction conversion ratio of 85% or more by a conventional emulsion polymerization method, the gel content of rubber Lanex is 90 to 95%, and the swelling index is about 14 to 20. .

However, in the present invention, in order to obtain a graft copolymer having excellent impact resistance, a small diameter rubber latex having 0.05 to 0.15 μ having a gel content of 70 to 90% and a swelling index of 25 to 40 was used.

The swelling index and the gel content defined in the present invention are as follows.

In addition, examples of the small-diameter rubber latex used in the present invention include a copolymer of butadiene containing 50% by weight or more of polybutadiene and butadiene and a monomer copolymerizable therewith, and specific examples of the monomer copolymerizable with butadiene Aromatic vinyl compounds, such as styrene, (alpha) -methylstyrene, and vinyltoluene, and vinyl cyanide compounds, such as an acrylonitrile and methacrylonitrile, etc., and all the compounds similar, substituted (compatible), or replaceable with these are mentioned.

Agglomerated large-diameter rubber latex is prepared using such a small-diameter rubber latex, and a large-diameter rubber latex having a particle diameter of 0.02 to 0.50 μ is prepared by using an agglomeration method with an acid as an agglomeration method. The amount, pH, temperature, amount of solids, etc. are controlled and these factors are well controlled to obtain the desired particle size.

② Graft Copolymerization Process

Graft copolymerization in this invention is performed using a conventional emulsifier, a molecular weight modifier, etc.

As the emulsifier, fatty acid salts such as rosin salts of potassium rosin, sodium rosin, potassium oleate, sodium stearate, alkyl aryl sulfonates and the like can be used.

As a molecular weight regulator, mercaptans, such as t-dodecyl mercaptan and n-dodecyl mercaptan, or terpenes, such as tabinolten, dipente, and t- derfiene, halogenated hydrocarbons, such as chloroform and carbon tetrachloride, can be used. have.

Examples of the aromatic vinyl compound used in the graft copolymerization include styrene, α-methylstyrene, and vinyl toluene. Acrylonitrile and methacrylonitrile may be used as the vinyl cyanide compound.

In addition, unsaturated carboxylic acids such as acrylic acid and methacrylic acid or their esters such as methyl, ethyl, propyl, n-butyl and isobutyl esters can be used, and vinyl acetate can also be used. Compatible) Any replaceable compound may be used.

Examples of the vinyl amide compound include acrylamide, methacrylamide, and ethyl methacrylamide, which may be used alone or in combination of two or more thereof. The use of these compounds in the present invention has improved latex stability and thermal stability.

As an initiator, an organic peroxide such as cumene hydroperoxide and diisopropylbenzene hydroperoxide and a pivalate system such as t-butyl peroxy pivalate may be used, and a redox system of the peroxide and a reducing agent may be used.

In general, the polymerization inhibitor is used to prevent the polymerization from occurring after the polymerization, but in the present invention, it is added in the middle of the polymerization to produce a continuous unit of acrylonitrile in which a water-soluble polymerization inhibitor is dissolved in water. Its purpose is to restrain.

That is, in order to suppress the generation of homopolymers of acrylonitrile dissolved in the water phase, polymerization is suppressed in the water phase and diffused into the micelle by using a water-soluble polymerization inhibitor. It was improved by inducing copolymerization with comonomer (styrene) in micelle).

Polymerization inhibitors used include pt-butylcatechol, α-nitroso-β-naphthol, di-t-amylhydroquinone, dinitro benzenethiol, dinitrophenylbenzothiazyl sulfide, sodium hydro sulfide, tetramethylthiuram Dialkyldithiocarbamate metal salts such as disulfide, tetramethylthiuramide sulfide, dinitrophenylpyridinium chloride, sodium dimethyldithio carbamate, potassium dimethyldithiocarbamate, nitric oxide, phenylhydrazine, hydroxy niphthyl Amines, p-nitrosomethylaniline, bis- (p-hydroxynaphthylamine), tetraethylenepentaamine, bis (p-hydroxyphenyl) amine, and the like. ) Any compound that can be substituted can be used.

In the graft copolymerization, the method of adding each component may be a method of administering the entire amount of each component at once, a method of dividing and adding, or a method of continuously administering the whole or part of the components.

In the present invention, it is used by dividing into two or three stages, in the first stage all the components are added in a batch and in the second stage, the emulsifier, monomer, molecular weight regulator, water is made into an emulsion and continuously added.

In addition, the initiator and the polymerization inhibitor are also added continuously.

After the two-stage polymerization, the reaction conversion is about 94%.

Therefore, in order to further increase the reaction conversion rate, a three-step reaction is performed to terminate the reaction. In the third step, a monomer, an initiator, and a polymerization inhibitor are continuously added.

In the processing of 100 parts by weight of the styrene resin prepared above, the use of 2 to 6 parts by weight of lubricant was used to improve thermal stability and to minimize the difference in physical properties between MD and TD.

In general, the use of excess lubricant has been avoided (prohibited) as styrene resin is well known in the art that the addition of excess lubricant lowers physical properties such as impact strength, tensile strength and high temperature elongation.

In the present invention, however, by using 2 to 6 parts by weight of the lubricant, the effect of shear stress can be minimized to prevent chromophore formation, thereby improving thermal stability, and by changing the processing conditions during extrusion, minimizing the physical property difference between MD and TD. By using the lubricating agent to minimize the difference in physical properties between MD and TD without changing the processing conditions.

In addition, when using 7 parts by weight or more of lubricant, the impact strength is extremely reduced, so the amount of the lubricant used in the present invention is preferably 2 to 6 parts by weight.

In the present invention, by using a resin composition consisting of 100 parts by weight of a high-nitrile styrene resin prepared in the above, 2 to parts by weight of lubricant, and uniformly mixed in a Henschell mixer, extrusion injection was performed to measure their physical properties. , Also, Extrusiometer 45 (GOTTFERT Co., Ltd.) was used to prepare a 2.5 mm sheet, and then a specimen was prepared to measure physical properties in the MD and TD directions.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

In the Examples and Comparative Examples, "parts" and "%" mean "parts by weight" and "% by weight".

The physical properties measured in Examples and Comparative Examples of the present invention were carried out by the following method.

A. Izod impact strength test

Measured according to the method of ASTM D 256

B. Melt Flow Indes (MI)

Measured at 220 ° C, 10kg of ASTM D 1238 method

C. Stress Cracking Test

The stress cracking resistance test of HCFC 141b and HCFC 123 and HCFC 141b mixtures was carried out using a 35 mm × 150 mm × 2 mm compression molded specimen in a stress cracking fixture (1.0% maximum strain), After standing for 24 hours at ambient temperature, the surface was observed and critical strain values were obtained.

(Circle): No surface change, and critical strain value is about 0.3% or more

△: critical strain value 0.15 or more but less than about 0.3%

×: surface defect, less than about 0.15% of critical strain value

D. Yellowness index (YI) measurement

The YI value was measured by the method of ASTM D 1925, and when the YI value is 45 or less, color control to white is possible.

E. High Temperature Tensile Test

As a measure of vacuum formability, a high temperature elongation was measured by a tensile test at an ambient temperature around about 140 ° C.

Dumbbell-type specimens of 51 × 15.2 × 1.8mm were used, and the diameter of the notches was 6.35mm and the gaps of the notches were 6.35mm.

It was determined that the vacuum formability was excellent when the high temperature elongation was about 80% or more.

F. Chemical Resistance Test

The chemical resistance test for HCFC 141b was measured by the method of ASTM D543, and the weight change was measured by immersing the specimen in HCFC for 1 day at ambient temperature around 23 ° C.

G. Thermal Stability Test

The YI (Yellowness Index) value was measured according to the injection machine residence time at the ambient temperature around 230 ℃.

H. MD / TD Elongation Deviation

2.5 mm sheet was calculated after measuring the elongation after preparing dumbbell-type specimens in the MD and TD directions, respectively.

Preparation Example 1

① Small Diameter Rubber Latex Manufacturing and Coagulation Process

1.3 parts by weight of 1.3-butadiene, 3.3 parts by weight of potassium oleate as an emulsifier, 0.3 parts of potassium persulfate as an initiator, 0.2 parts of tertiary dodecyl mercaptan as a chain transfer agent, and 150 parts of water were added to a reaction tank, and the reaction temperature was raised to 55 ° C. Proceeded.

When conversion reached 30%, 0.1 weight part of tertiary dodecyl mercaptans were further added, and reaction temperature was raised to 60 degreeC.

Then, when the conversion rate reached 85%, the reaction was stopped by administering diethylhydroxyamine, and the unreacted monomer was recovered to obtain a small diameter rubber latex (A) having an average particle diameter of 0.09 µ, a gel content of 83%, and a swelling index of 35. Got.

A small diameter rubber latex (A) was used to prepare a large diameter rubber latex (B) having an average particle diameter of 0.25 to 0.35 mu using an aggregation method using an acid.

② Preparation of Graft Copolymer

Stage 1

The above components were collectively added to the reactor and polymerization was carried out for 1 hour at a reaction temperature of 60 deg.

(If necessary, the ingredients may be divided and added sequentially.)

Tier 2

The monomer, molecular weight modifier, and water in the above components were made into an emulsion, and continuously added over 3 hours (divided sequentially), and a reducing agent aqueous solution, an initiator, and a polymerization inhibitor were continuously added for 3 hours.

At this time, the reaction temperature was 65 ° C.

Tier 3

Subsequently, the reaction temperature was set at about 65 ° C ambient temperature, and the above components were continuously added over about 1 hour, and then aged for about 1 hour and the reaction was terminated.

The reaction conversion rate at this time was about 99%.

An antioxidant was added thereto, followed by coagulation with an aqueous 5% sulfuric acid solution, followed by washing and drying to obtain a powder graft polymer.

This is hereinafter referred to as G-ABS.

Preparation Example 2

All the components except the monomer, the initiator, and the polymerization inhibitor were added to the reactor, the reaction temperature was 65 ° C., and the monomer, the molecular weight regulator, the initiator, and the polymerization inhibitor were added over 5 hours (divided sequentially).

It was solidified with 5% aqueous sulfuric acid solution, washed and dried to obtain a copolymer.

Hereinafter referred to as SAN II.

Preparation Example 3

Bulk polymerization was carried out using 32% by weight of acrylonitrile and 68% by weight of styrene.

Hereafter referred to as SAN I.

Example 1

60 parts of G-ABS (Production Example 1), 40 parts of SAN I, 1.5 parts of butylidene bisphenol, and 3.0 parts of ethylene bis steamide were added to a Henschell mixer, uniformly mixed, and extruded to prepare a specimen.

Physical properties were measured and shown in Table 1.

Example 2

Except for using 40 parts SAN II instead of SAN I in Example 1 and was carried out in the same manner as in Example 1 and the results are shown in Table 1.

Example 3

Except for using 3.0 parts of ethylene bis steamide in Example 1 2.5 parts, 2.5 parts of polyester was used in the same manner as in Example 1, the results are shown in Table 1.

Comparative Example 1

Except for using 2.0 parts of ethylene bis steamide in Example 2 was carried out in the same manner as in Example 1 and the results are shown in Table 1.

Comparative Example 2

Except for using 7.0 parts of ethylene bis steamide in Example 2 was carried out in the same manner as in Example 1 and the results are shown in Table 1.

TABLE 1

Claims (4)

50 to 80% by weight of vinyl cyanide compound, 20 to 50% by weight of aromatic vinyl compound and 5% by weight of unsaturated carboxylic acid, esters thereof or vinyl acetate in the presence of 10 to 50 parts by weight of rubber latex, up to 15% by weight The graft copolymer (A) prepared by using 0.001 to 2.0 parts by weight of the polymerization inhibitor during the graft polymerization using 50 to 90 parts by weight of the vinylamide compound, 50 to 80% by weight of the vinyl cyanated compound and 20 to 50% by weight Copolymer (B) or vinyl cyanide compound prepared using 2.0 parts by weight or less of polymerization inhibitor in polymerization of aromatic vinyl compound and 5% by weight or less of unsaturated carboxylic acid or esters thereof, and 60 to 40% by weight of aromatic vinyl compound Paraffin wax, polyethylene wax, polypropylene wax, ethylene bis steamide, 100 parts by weight of a styrene-based resin in which a copolymer (C) composed of 75% by weight is mixed so that the rubber content is 10-30% by weight. Styrene resin composition, characterized by configured thiazol esters, barium stearate, calcium stearate chosen from, alone or in combination of two or more in combination a lubricant 3-6 parts by weight. The resin composition according to claim 1, wherein 30% by weight or less of rubber latex having an average particle diameter of 0.05 to 0.15 mu and 70 to 100% by weight of rubber latex having an average particle diameter of 0.2 to 0.5 mu are used. The resin composition according to claim 2, wherein the gel content of the rubber is 70 to 90% by weight. The method of claim 1, wherein the polymerization inhibitor is pt-butylcatechol, α-nitroso-β-naphthol, di-t-amylhydro quinone, dinitrobenzenethiol, dinitrophenylbenzothiazyl sulfide, sodium, hydro sulfide, Dialkyldithio carbamate metal salt nitrile oxides, phenylhydrazine, such as tetramethylthiuram disulfide, tetramethylthiuramide-sulfide, dinitro phenylpyridinium chloride, sodium dimethyldithiocarbamate, potassium dimethyl dithiocarbamate Hydroxynaphthylamine, p-nitrosomethylaniline, tetraethylene pentaamine, bis (p-hydroxynaphthyl) amine, p-nitrosomethylaniline, tetraethylenepentaamine or bis- (p-hydroxyphenyl Styrene-based resin composition, characterized in that used in the amine.