KR0142628B1 - Polystyrene resin wannfacfuring method - Google Patents

Abstract

The present invention relates to a method for producing a high impact rubber modified polystyrene resin that can be used as an inner phase material of an electric refrigerator, which has a good resistance to cyclopentane and a good mechanical property, and is compatible with rubber modified polystyrene resin (I). Graft copolymer resin obtained by graft co-polymerization of 40 to 85 parts by weight of a monomer mixture composed of 15 to 60 parts by weight of an unsaturated nitrile 5 to 20% by weight of an alkenyl aromatic hydrocarbon. ), And the weight ratio of resin (I) and resin (II) is mixed in the range of 0.6-6.

Description

Manufacturing method of high impact rubber modified polystyrene resin having excellent solvent resistance

The present invention relates to a method for producing a rubber-modified polystyrene resin that can be used as an inner phase material of an electric refrigerator having good resistance to cyclopentane and good mechanical properties.

BACKGROUND ART As an inner phase material of an electric refrigerator, an ABS resin prepared by mixing a styrene-acrylonitrile resin (SAN) with a resin obtained by graft copolymerization of styrene and acrylonitrile on a diene rubber polymer (graft ABS) is widely used. .

The internal resin of the electric refrigerator is first produced in a sheet state by an extruder, which is produced in an internal form through vacuum molding or compression molding. Urethane is injected and foamed between the wound-molded article and the outer plate made of iron plate to form a refrigerator body. At this time, CFC (commonly referred to as Freon) has been widely used as a blowing agent of urethane. Recently, it has been known that CFC-11 destroys the ozone layer, causing environmental problems. It is replacing CFC-11 with HCFC-141b (usually an alternative Freon name).

However, since the ozone layer destruction degree is lower than that of the alternative freon freon, it can also destroy the ozone layer, so some advanced home appliance industries use cyclopentane as a urethane foaming agent, which does not destroy the ozone layer at all. In addition, cyclopentane has less chemical influence than Freon, which is a conventional blowing agent, and thus it is possible to use rubber-modified polystyrene instead of the conventional ABC resin in the refrigerator. However, rubber-modified polystyrene is not sufficiently resistant to cyclopentane, causing swelling and cracks in the inner phase, making it invaluable as a commodity.

It is known that swelling in the refrigerator occurs due to the temperature and pressure when urethane, which is an insulation, is injected together with a blowing agent. If voids exist at the interface between the urethane foam and the internal resin after the reaction, the foaming agent stays in the voids, resulting in the appearance of swelling at high temperatures and shrinkage at low temperatures due to changes in ambient temperature. It is affected by the absorbency of the components. In other words, when the water-resistant resin absorbs a large amount of the blowing agent component, the elastic modulus decreases, which inevitably causes deformation.

In addition, cracks in the internal resin are caused by stress due to the difference in thermal expansion coefficient between the steel plate, polyurethane foam, and the material of the internal resin, and the foaming agent used rapidly lowers the intermolecular attraction of the internal resin, which eventually develops into internal cracks. This is because the resin has low environmental stress cracking resistance (ESCR) against the blowing agent.

Therefore, in order to improve the deformation prevention of rubber-modified polystyrene resins and environmental stress cracking resistance to cyclopentane, conventionally, the thickness of rubber-modified polystyrene resin-resistant molded articles has been increased. However, the conventional method is not only able to sufficiently solve the deformation of the internal resin and environmental stress cracking problems, but also has the disadvantages such as the cost increase due to the increase in thickness and the content of the refrigerator is reduced, and also the rubber produced by the continuous polymerization method Due to the nature of the modified polystyrene resin manufacturing process, the amount of rubber components used is limited, and thus there is a problem in that mechanical properties including impact strength required as a refrigerator inner material are not satisfied.

In the present invention to solve the above problems, the environmental stress cracking resistance to cyclopentane is large, the absorption of cyclopentane is low, and not only satisfies all the mechanical properties required as the inside of the refrigerator, but also excellent for sheet molding, vacuum molding, etc. An object of the present invention is to provide a rubber-modified polystyrene-based resin manufacturing method having workability.

In order to achieve the above object, the present inventors have found that acrylonitrile-butadiene-styrene copolymer having a low content of acrylonitrile component compatible with rubber-modified polystyrene resin having a specific diameter of rubber ( It was found that the rubber modified polystyrene-based resin having excellent solvent resistance and improved physical properties including impact properties is produced by mixing and mixing ABS).

That is, the present invention is compatible with rubber-modified polystyrene resins (I) and resins (I) in which 4 to 15 parts by weight of butadiene rubber polymer having a particle size in the range of 1-3 micron is contained in 88-96 parts by weight of the matrix polystyrene resin. Graft copolymer resin (II) -rubber polymer 15 to 60 parts by weight of the monomer mixture composed of 5 to 20% by weight of unsaturated nitrile and 80 to 95% by weight of alkenyl aromatic hydrocarbons by graft polymerization A copolymer resin having solvent resistance to pentane is prepared, and the weight ratio of the resin (I) and the resin (II) is mixed in parts by weight in the range of 0.6-6.

The present invention is described in detail as follows.

The butadiene rubber polymer of the resin (I) used in the present invention may be a butadiene homopolymer, a butadiene-styrene copolymer, an isoprene polymer, a butadiene-acrylonitrile copolymer and the like, but preferably a butadiene homopolymer.

In addition, the basic raw material occupying most of the resin (I) is an alkenyl aromatic hydrocarbon, and examples thereof include styrene, alphamethylstyrene, 2,4-dimethylstyrene, metamethylstyrene, 0-methylstyrene, and P-methylstyrene. As the furnace, styrene, alpha methyl styrene, a mixture of styrene and acrylonitrile, and the like are preferable, and a rubber-modified polystyrene resin (I) produced by a conventional bulk continuous polymerization method can be used. When the average particle size of the rubber particles in the rubber-modified polystyrene resin used is smaller than 1 micron or less, impact resistance is reduced, and when it is 3 microns or more, it is impossible to satisfy various physical properties of the refrigerator inner material.

Examples of the rubber polymer of the rubber polymer latex used in the preparation of the resin (II) of the present invention include polybutadiene, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, isoprene rubber, acrylic rubber, and the like. Or mixtures thereof. Moreover, as an unsaturated nitrile used as a monomer, they are acrylonitrile, methacrylonitrile, etaacrylonitrile, etc., As an alkenyl aromatic hydrocarbon, styrene, alphamethyl styrene, etc. can be illustrated.

Examples of radical initiators include potassium persulfate, sodium persulfate, ammonium persulfate or hydroperoxide. As the emulsifier used in the emulsion polymerization, a general emulsifier can be used, but an anionic emulsifier is preferably an anionic emulsifier. Can be.

In this invention, appropriate content of the rubber-polymer content rate in resin (II) is 50-60 weight part. When the rubber content is lower than 15 parts by weight, there is a lack of impact resistance and cracks occur. When the rubber content exceeds 60 parts by weight, not only the solvent resistance is insufficient but also the polymerization stability is greatly reduced. In addition, the monomer mixture used in the graft copolymerization may be used with 5 to 20% by weight of unsaturated nitrile and 80 to 95% by weight of alkenylaromatic hydrocarbon. If the content of unsaturated nitrile is 5% by weight or less, the nitrile original properties such as solvent resistance are insufficient, and when the content of unsaturated nitrile is 20% by weight or more, compatibility with resin (I) is insufficient and overall physical properties are lowered.

The thermoplastic resin obtained by the above production method has excellent solvent resistance and excellent impact characteristics, so its business value is high.

Examples and comparative examples of the present invention are as follows.

The following parts and percentages are based on weight unless otherwise specified.

Preparation Example 1

[Production of Resin (I-a)]

In a conventional bulk continuous polymerization reactor, 93 parts of styrene monomer is mixed and polymerized in the presence of 7 parts of polybutadiene homopolymer. In step 1, the rubber polymer was dissolved by stirring at 50 ° C for 1-3 hours. At the same time as the rubber polymer, the additive is dissolved and continuously fed to the first reactor through a preheating process of 70-90 ° C. Heated to 120 ° C. in the first reactor and operated at 35 rpm with an anchor stirrer to maintain 34-35% polymerization.

The polymer is continuously transferred to a second reactor at 170 ° C. and an additive for molecular weight control and impact reinforcement is introduced in the second reactor. The polymerization rate in the second reactor is about 70-75%, after which the resin is prepared through a devolatilization process.

Production Example 2

[Production of Resin (I-b)]

A resin was prepared in the same manner as in Preparation Example 1, except that 10 parts of the polybutadiene homopolymer was prepared in the process of Preparation Example 1 and 90 parts of the styrene monomer was added and mixed.

Preparation Example 3

[Production of Resin (II-a)]

In a nitrogen-substituted reactor, 25 parts of polybutadiene rubbery polymer latex having an average particle diameter of 0.3 micron and a gel content of 80% (based on solids), 200 parts of deionized water, 1.5 parts of unbalanced potassium rosin, and 0.2 parts of condensate of sodium naphthalene sulfonate and formaldehyde , 0.02 parts of potassium hydroxide, 0.35 parts of dextrose, 0.1 part of hydroperoxide, 0.1 part of t-dodecylmercaptan, 1.5 parts of acrylonitrile and 13.5 parts of styrene were injected into the reactor with stirring, and the mixture was heated to 65 ° C.

After sufficiently stirring the latex, an aqueous solution consisting of 0.2 parts of sodium pyrophosphate and 0.01 part of ferrous sulfate was added to initiate a polymerization reaction. Successively, a mixture of 6 parts of acrylonitrile, 54 parts of styrene, 0.1 part of t-dodecylmercaptan, and 0.1 part of hydroperoxide was added to the latex over 2 hours to complete the reaction.

The resulting polymer latex was added with 0.1 part of butylated methylphenol as an antioxidant, solidified with aqueous sulfuric acid solution, washed and dried to obtain resin (II-a).

Production Example 4

[Production of Resin (II-b)]

Into a polymerization reactor containing 40 parts of polybutadiene rubbery polymer latex, 0.07 parts of hydroperoxide, 0.1 part of t-dodecylmercaptan, 1.4 parts of acrylonitrile, 7.7 parts of styrene, and 7.6 parts of acrylonitrile and 43.3 parts of styrene A monomer mixture was prepared in the same manner as in Preparation Example 3 except that the mixture was continuously added for 2 hours.

Production Example 5

[Production of Resin (II-c)]

0.1 parts of hydroperoxide, 0.15 parts of t-dodecylmercaptan, 2.4 parts of acrylonitrile, 13.6 parts of styrene, and 9.6 parts of acrylonitrile and 54.4 parts of styrene in a polymerization reactor having 20 parts of polybutadiene rubbery polymer latex. , 0.1 parts of t-dodecylmercaptan 0.1 parts of hydroperoxide was carried out in the same manner as in Preparation Example 3 except that the monomer mixture was continuously added for 3 hours.

Preparation Example 6

[Production of Resin (II-d)]

0.2 parts of hydroperoxide, 0.2 parts of t-dodecylmercaptan, 1.4 parts of acrylonitrile, 12 parts of styrene were initially added to a polymerization reactor in which 12 parts of polybutadiene rubbery polymer latex was present, and 7.4 parts of styrene nitrile continuously fed and styrene 67.2 Part, t-dodecylmercaptan 0.1 part Hydrogen peroxide monomer mixture was carried out in the same manner as in Preparation Example 3 except that the monomer mixture consisting of 0.1 parts of hydroperoxide for 3 hours.

Production Example 7

[Production of Resin (II-e)]

0.1 parts of hydroperoxide, 0.1 parts of t-dodecylmercaptan, 3.8 parts of acrylonitrile and 12.1 parts of styrene were initially charged in a polymerization reactor in which 20 parts of polybutadiene rubbery polymer latex was present, and 15.4 parts of acrylonitrile continuously fed and styrene 48.7 Part, t-dodecylmercaptan 0.1 part Hydrogen peroxide monomer mixture was prepared in the same manner as in Preparation Example 3 except that the mixture was continuously added for 2.5 hours.

Example 1

The resin (II-a) polymer obtained in Production Example 3 and the resin (I-a) polymer obtained in Production Example 1 were mixed at the ratios shown in Table 1, and 0.4 parts of antioxidant and 0.4 parts of lubricant were added and mixed. After extrusion it was pelletized to prepare a specimen. The physical properties of the obtained specimens are shown in Table 1 below, and the evaluation methods for the physical properties of the prepared specimens are as follows.

* Environmental stress cracking resistance: A test piece of 2 mm x 130 mm x 40 mm made by compression molding is fixed to a jig that is divided into quarters of an ellipse represented by the formula 5X ² + 24Y ² = (unit: cm). After injecting 100 ml of cyclopentane into a desiccator having a volume of 5 L, the sample was left at 30 ° C. for 8 hours, and then the critical strain was calculated by a conventional method.

* Mechanical Properties: General mechanical properties are based on the method specified in ASTM.

Example 2

The same procedure as in Example 1 was carried out except that the resin (II-b) polymer obtained in Preparation Example 4 was used instead of the resin (II-a) obtained in Preparation Example 3.

Example 3

The same procedure as in Example 1 was carried out except that the resin (II-c) polymer obtained in Preparation Example 5 was used instead of the resin (II-a) obtained in Preparation Example 3.

Example 4

The same procedure as in Example 1 was carried out except that the resin (I-b) polymer obtained in Preparation Example 2 was used instead of the resin (I-a) polymer obtained in Preparation Example 1.

Example 5

The same procedure as in Example 2 was carried out except that the resin (I-b) polymer obtained in Preparation Example 2 was used instead of the resin (I-a) polymer obtained in Preparation Example 1.

Example 6

The same procedure as in Example 3 was carried out except that the resin (I-b) polymer obtained in Preparation Example 2 was used instead of the resin (I-a) polymer obtained in Preparation Example 1.

Comparative Example 1

The same procedure as in Example 1 was carried out except that the resin (II-d) polymer obtained in Preparation Example 6 was used instead of the resin (II-a) obtained in Preparation Example 3.

Comparative Example 2

The same procedure as in Example 1 was carried out except that the resin (II-e) polymer obtained in Preparation Example 7 was used instead of the resin (II-a) obtained in Preparation Example 3.

Comparative Example 3

The same procedure as in Example 4 was carried out except that the resin (II-d) polymer obtained in Preparation Example 6 was used instead of the resin (II-a) obtained in Preparation Example 3.

[Comparative Example 4]

The same procedure as in Example 4 was carried out except that the resin (II-e) polymer obtained in Preparation Example 7 was used instead of the resin (II-a) obtained in Preparation Example 3.

Claims (3)

15 to 60 parts by weight of butadiene-based rubber polymer compatible with rubber-modified polystyrene resin (I), 40 to 85 parts by weight of a monomer mixture consisting of 80 to 95% by weight of unsaturated nitrile 5 to 20% by weight alkenyl aromatic hydrocarbon A method for producing a rubber-modified polystyrene resin, comprising producing graft copolymer resin (II) obtained by copolymerization and mixing a weight ratio of resin (I) and resin (II) in the range of 0.6 to 6. The method for producing a rubber-modified polystyrene resin according to claim 1, wherein the rubber-modified polystyrene resin (I) to be used has an average size of rubber particles of 1-3 microns of the butadiene rubber polymer dispersed in the polystyrene resin. The rubber polymer used in the manufacture of graft copolymer resin (II) is at least one selected from polybutadiene, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, isoprene rubber, and acrylic rubber. The manufacturing method of rubber-modified polystyrene resin made into.