JPH08245856A - Abs resin composition and molded product thereof - Google Patents

Abstract

PURPOSE: To obtain an ABS resin composition which can give a molded product reduced in a distribution of wall thicknesses and is excellent in low-temperature impact strength by specifying its melt flow rate and its die swell ratio. CONSTITUTION: This ABS resin has a melt flow rate of 1-20 at 220 deg.C and a die swell ratio of 20-200. To mix the components of this composition, common mixers can be used. Among them, a vented extruder is desirable. A molded product of this composition can be obtained by a vacuum molding process or a pressure molding process. When the melt flow rate of this composition is below 1, the composition can not give a desired molded product by a pressure molding process due to the insufficient deformation of resin. On the contrary, when it is above 20, the deformation of the resin is excessive, the handling of the heated sheet to the molding machine is difficult and the impact strength of the molded product lowers.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel ABS resin composition and a molded article thereof.

[0002]

2. Description of the Related Art Demand for large office equipment and the like has increased with the recent information society, and resin is used for the chassis for weight reduction. Also, resin moldings are used for large-scale water products such as washbasins and analytical instruments. These large-sized resin molded products are often molded by pressure molding or vacuum molding in addition to injection molding from the viewpoint of mold making.

Incidentally, in vacuum molding, and particularly in pressure molding, there is a problem of wall pressure distribution, which is different from injection molding, and the resins conventionally used have been extremely limited. ABS
The resin has many advantages such as impact strength at low temperature, but it has not been widely used for vacuum forming and pressure forming due to its moldability.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin molding having a small wall pressure distribution and an excellent impact strength at low temperature.

[0005]

The present invention provides an ABS resin composition having a melt flow rate at 220 ° C. of 1 or more and 20 or less and a die swell ratio of 20 or more and 200 or less, and It is intended to provide a resin molded product molded by vacuum molding or pressure molding using the resin composition. The present invention will be described in detail below.

The ABS resin composition of the present invention is adjusted so that the melt flow rate is from 1 to 20. It is more preferably adjusted to 5 or more and 15 or less. If the melt flow rate is less than 1, the desired resin cannot be obtained due to insufficient deformation of the resin during pressure molding. When it exceeds 20, the deformation of the resin is so great that it is difficult to handle the sheet after heating it to the molding machine, and the impact strength of the molded product is also lowered. The melt flow rate can be adjusted by adjusting the amount of rubber in the ABS resin composition, the particle size of the graft polymer, and the molecular weight of the copolymer obtained by polymerizing monomers containing aromatic vinyl and vinyl cyanide. It is done by.

The ABS resin composition of the present invention has a die swell ratio of 20 or more 2 under the conditions of melt flow rate measurement.
00 or less. Die swell ratio is 2
If it is less than 0, good wall thickness uniformity cannot be obtained. If it exceeds 200, it is difficult to form a sheet. As the method of adjusting the die swell, a method of adding another resin having a high molecular weight as a fluidity adjusting agent, a method of expanding the molecular weight distribution of the copolymer (B) to a high molecular weight side, and a method of branching into the molecules of the copolymer (B) There are a method of giving a structure, a method of adding another thermoplastic resin having a specific compatibility with the graft polymer (A) or the copolymer (B), and the like.

The ABS resin referred to in the present invention is a graft weight obtained by graft-polymerizing a rubber (1) made of a monomer containing butadiene with a monomer containing aromatic vinyl or vinyl cyanide. It is a resin containing a polymer (A), an aromatic vinyl, a vinyl cyanide, and / or a copolymer (B) produced from other copolymerizable monomers. It is essential that the rubber (1) used in the graft polymer (A) contains butadiene, and in addition, it is copolymerized with butadiene such as aromatic vinyl, vinyl cyanide, (meth) acrylic acid ester and vinyl carboxylate compound. It is also possible to copolymerize the other monomer. The content of butadiene in the rubber is preferably 70% by weight or more, more preferably 80% by weight or more. Examples include polybutadiene, styrene-butadiene copolymer, diene-based copolymer such as acrylonitrile-butadiene copolymer, hydrogenated diene-based polymer, and the like. Among these, polybutadiene is preferable.

The graft polymer (A) can be obtained by graft-polymerizing aromatic vinyl or vinyl cyanide on the rubber (1). At that time, if necessary, a (meth) acrylic acid ester, a vinyl carboxylate compound, Other copolymerizable monomers such as maleimide vinyl compounds may also be used together in the graft polymerization. The rubber (1) in the graft polymer is preferably adjusted to 5% by weight to 70% by weight, more preferably 10% by weight to 60% by weight. The aromatic vinyl compound in the monomer to be graft-polymerized is 30% by weight to 80% by weight.
It is desirable to adjust the content to be 40% by weight, and it is more desirable to adjust the content to be 40 to 70% by weight. The vinyl cyanide compound in the monomer to be graft-polymerized is preferably adjusted to be 5% by weight to 80% by weight, more preferably 10% by weight to 70% by weight.

The copolymer (B) can be obtained in the course of the graft polymerization of the graft polymer (A) or by separately copolymerizing aromatic vinyl and vinyl cyanide. Other copolymerizable monomers such as (meth) acrylic acid ester, vinyl carboxylate compound, and maleimide vinyl compound can also be used together. The aromatic vinyl compound in the copolymer (B) is 30% by weight to 8%.
It is preferably adjusted to 0% by weight, more preferably 40% to 70% by weight. The vinyl cyanide compound in the copolymer (B) is preferably adjusted to 5% by weight to 80% by weight, more preferably 10% by weight to 70% by weight.

The aromatic vinyl used in the rubber (1), the graft polymer (A) and the copolymer (B) includes styrene, α-methylstyrene, α-chlorostyrene, bromostyrene and p-methyl. Styrene etc.
Species or a mixture of two or more species is used. Of these, styrene and α-methylstyrene are preferable. Also rubber (1),
It is optional to use different aromatic vinyls or the same aromatic vinyls for the graft polymer (A) and the copolymer (B).

Similarly, examples of the vinyl cyanide used in the rubber (1), the graft polymer (A) and the copolymer (B) include acrylonitrile and methacrylonitrile. Are mixed and used. After all, different vinyl cyanides or the same vinyl cyanide may be used. Examples of the maleimide vinyl compound used in the graft polymer (A) and the copolymer (B) include an N-alkyl-substituted maleimide having an alkyl group having 1 to 4 carbon atoms, N-phenylmaleimide, and a nucleus-substituted N-phenylmaleimide. , N-cyclohexylmaleimide and the like. Among these, N-phenylmaleimide is preferable. The N-substituted maleimide also includes, for example, one obtained by copolymerizing maleic anhydride and then imidizing it with aniline or the like.

Graft polymer (A) and copolymer (B)
Examples of the (meth) acrylic acid ester used in the above include an alkyl group having 1 to 12 carbon atoms such as methyl methacrylate, and an alkyl group having 1 to 12 carbon atoms such as methyl acrylate. . Examples of the vinyl carboxylate compound used in the graft polymer (A) and the copolymer (B) include acrylic acid, maleic anhydride and methacrylic acid.

The rubber (1) is produced by solution polymerization, bulk polymerization,
Either emulsion polymerization can be used. When the graft polymerization in the latter step is carried out in an emulsion state, it is produced by solution or bulk polymerization and then emulsified if necessary, or it is originally produced by emulsion polymerization. Graft polymer (A)
Can be obtained by graft-polymerizing the above-obtained rubber with aromatic vinyl, vinyl cyanide or another copolymerizable monomer. Graft polymerization is solution polymerization, bulk polymerization,
Although emulsion polymerization can be performed, emulsion polymerization is preferable.
A non-graft copolymer may be formed as a by-product in the process of this graft polymerization, and this is contained in the copolymer (B).

When the copolymer (B) is produced in a separate step, it may be solution, bulk or emulsion polymerization. The ABS resin of the present invention contains the above-mentioned graft polymer (A) and copolymer (B), but if necessary, other thermoplastic resin, and in addition, a lubricant, an antistatic agent, an antioxidant, It is also possible to add flame retardants, UV absorbers, colorants, foaming agents, fibrous or granular inorganic fillers, or other compounding agents / additives commonly used in thermoplastic resin compositions. Of these, it is particularly desirable to add a lubricant and an antioxidant.

Other resins that can be added to the ABS resin of the present invention include polycarbonate, thermoplastic polyurethane, polyester and acrylic resin. For mixing the respective components of the ABS resin of the present invention, various mixing devices generally used for thermoplastic resins, such as a vented extruder, a plastomill, a kneader, a Banbury mixer, and a Brabender, can be used.
Of these, a vented extruder is preferred.

The molded product of the present invention is molded by a vacuum molding method or a pressure molding method. Pneumatic molding is a method of making a molded product by first molding resin into a sheet shape, sandwiching it on a mold and pulling it from one side by depressurizing to the mold and pressing the other by pressing it to the mold. is there. Vacuum forming is a forming method performed in the same manner as pressure forming, except that pressure is not applied from the other side. A method is also often used in which a slight pressure is applied just before attracting to the vacuum side to temporarily inflate the side opposite to the die and then attracting to the die side.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to the scope of the following examples. Parts and% in the examples are by weight unless otherwise specified. In addition, various measurements are
It depends on the procedure. (1) Melt flow rate (MFR) Measured according to JIS K-7210 (220 ° C, 10 kg load). (2) Die swell Calculated by the following formula from the ratio of the maximum diameter Dp of the resin rod obtained under the above MFR measurement conditions and the diameter Dd of the die part of the melt flow rate measuring machine.

Die swell = 100 × (Dp−Dd) / Dd (3) Uniformity of wall pressure in pneumatic molding The pneumatic molding tester has an opening framed in a square with an inner diameter of 40 cm and an outer diameter of 50 cm at the bottom. It consists of a lower mold with an opening in the upper part that has a frame of the same shape as the mold, and when the upper and lower parts are stacked, it is designed so that a cubic space with a side of 40 cm is formed in the center, the depth of the lower part is 30 cm, the ceiling of the upper part Height is 1
It is 0 cm. In the lower part, 1 is evenly spaced on the bottom 4 sides of the inner surface.
Six 1mm diameter holes are drilled and minus 100 through the valve.
It is connected to a vacuum reservoir with a volume of 96 liters adjusted to hectopascals. A hole with a diameter of 10 mm is formed in the center of the upper part, and the upper part is connected to a pressure reservoir having a volume of 80 liters adjusted to 5000 hectopascals through a valve.

After heating a resin plate having a thickness of 2 mm and a side of 50 cm to 130 #C by an infrared heater, it is sandwiched between the upper mold and the lower mold of the compressed air molding tester to fix the upper and lower molds. Open the valve from the lower die to the pressure reservoir and the valve from the upper die to the pressure reservoir to perform molding. The mold is opened, the molded product is taken out, and the wall pressure at the lower corners of the molded product corresponding to the four corners of the lower mold is measured, and the wall pressure uniformity is 5 (A (good), B, C, D, E (poor)). Evaluate in stages. (4) Preparation of test piece The test piece used was injection molded at 260 ° C. (5) Izod strength Measured in accordance with ASTM D-256 (1/4 inch, notched). (6) Heat distortion temperature ASTM D-648 (1/2 inch, 18.6 kg /
It was measured according to cm ² ). (7) Molecular weight distribution High performance liquid chromatography CCPD manufactured by Toso Corporation
Was measured under the conditions of 38 ° C. and 1 ml / min using THF as a mobile phase.

[0021]

Reference Example 1 (Preparation of Resin Composition A-1) 40 parts of polybutadiene rubber latex (solid part) and 100 parts of deionized water were placed in a polymerization tank equipped with a reflux condenser, and the gas phase part was replaced with nitrogen to 70 ℃
Warmed to. Then, while maintaining this temperature, a mixture of 45 parts of styrene, 15 parts of acrylonitrile, 0.3 part of t-dodecyl mercaptan and 0.2 part of cumene hydroperoxide, and 50 parts of deionized water and formaldehyde sulfoxyl were added thereto. An aqueous solution containing 0.2 part of sodium acid salt, 0.004 part of ferrous sulfate, and 0.008 part of disodium ethylenediaminetetraacetate was continuously added over 5 hours for reaction. The temperature was kept for another 30 minutes to complete the reaction. After the obtained latex was subjected to a monomer removal treatment by a steam stripping method, a resin component was precipitated using a coagulant, washed, filtered and dried to obtain a dry powder of a graft copolymer.

[0022]

[Reference Example 2] (Production of Resin Compositions B-1 to 3) Using a completely mixed continuous reactor (temperature controlled at 110 to 119 ° C), acrylonitrile,
A solution consisting of styrene, ethylbenzene and α-methylstyrene dimer and a polymerization initiator solution were continuously added at a constant rate, and the product was discharged so as to keep the polymerization reaction rate in the polymerization vessel constant, and an acrylonitrile-styrene-copolymer Was continuously obtained. Various compositions were obtained by changing the monomer composition to be added, and these were further mixed to obtain thermoplastic copolymers B-1 to 3 having the respective compositions shown in Table 1.

[0023]

Examples 1 to 4 and Comparative Example 1 Graft polymer (A), copolymer (B), each component of fluidity modifier and lubricant (ethylenebisstearylamide) 0.5 shown in the formulation of Table 2 Section and antioxidant (Sumitomo Chemical Co., Ltd. Sumilizer BH
T) 0.5 part was mixed with a Henschel mixer, and melt-kneaded at 260 ° C. using a vented extruder to prepare pellets. Using these pellets, injection molded test pieces were molded and various performances were measured. In addition, the moldability was measured using various molding machines. Table 3 shows the results.

As shown in Table 3, Examples 1 to 4 of the present invention
Has better moldability and mechanical properties than Comparative Example 1.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

The composition of the present invention is excellent in uniformity of meat pressure and mechanical properties, and is extremely useful as a material for a resin molded product.

Claims (2)

[Claims] 1. A melt flow rate at 220 ° C. of 1 or more and 20 or less and a die swell ratio of 20.
The ABS resin composition is 200 or more and 200 or less. 2. A molded product comprising the resin composition according to claim 1, which is molded by vacuum molding or pressure molding.