JPH0987462A - Rubber-reinforced styrenic resin composition and molded product therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber-modified styrenic resin composition excellent in impact resistance, oil resistance and molding processability and excellent in performances required for exterior materials, packaging materials and foamed molded products, and further to obtain a molded product therefrom. SOLUTION: This resin composition comprises 100 pts.wt. of the below- described component (A) and 10-250 pts.wt. of the below-described component (B), and injection molded products, extrusion molded products and foamed molded products are obtained by using the resin composition. (A) A rubber- modified styrenic resin containing soft component particles in an amount of 5-30wt.%, wherein the average particle diameter and swelling degree of the soft component particles are 0.1-2.5μm and 3-30, respectively. (B) A polymer having a solubility parameter(SP) of 8.45-8.70 and not containing an aromatic vinyl compound unit in the polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber-modified styrenic resin composition excellent in impact strength and oil resistance, and more specifically, it has improved impact strength and oil resistance and, at the same time, has other physical properties. The present invention relates to a rubber-modified styrene resin composition whose molding processability is not deteriorated.

[0002]

2. Description of the Related Art In the field of applications such as office automation equipment and home electric appliances, it is required that workability at the time of molding, finished dimensional accuracy of processed products, mechanical properties such as tension and bending, and various physical properties such as heat resistance are well balanced. Although it is required, improvement in impact strength is further required especially in terms of moldability and exterior materials. Such demands have become increasingly high in recent years. As a method of improving impact strength, a method of adding a soft component such as a styrene-butadiene copolymer to a rubber-modified styrene resin is well known. However, since the butadiene portion of these soft components has low heat resistance, if they stay at a high temperature (about 180 ° C to 250 ° C) during molding, a gel component will be generated and they will remain in the molded product as bumps and leave a rough surface. However, there is a problem that the appearance is deteriorated.
Further, in order to prevent these gel components from entering the molded product, it is necessary to purge a large amount of resin, which requires a long time and a large amount of resin. Also, when used as a packaging material, a high level of impact strength is required. Particularly when used for food applications, oil resistance may be required. When it is used as a cushioning material, one of the essential characteristics that it should have is that it has excellent shock absorption. However, the rubber-modified styrene-based resin composition is not necessarily sufficient in view of satisfying all the above requirements.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above problems and to provide excellent impact strength, oil resistance and molding processability, and excellent performance required for exterior materials, packaging materials, and foamed molded articles. Another object of the present invention is to provide a rubber-modified styrene resin composition and a molded product thereof.

[0004]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, one aspect of the present invention relates to a rubber-modified styrene resin composition containing more than 10 parts by weight and 250 parts by weight or less of the component (B) with respect to 100 parts by weight of the following component (A). Is. (A): Rubber modification containing 5 to 35% by weight of soft component particles, having an average particle size of the soft component particles of 0.1 to 2.5 μm, and a swelling degree of the soft component particles of 3 to 30. Styrenic resin (B): solubility parameter (SP) is 8.45 to 8.7.
0, and the polymer does not contain an aromatic vinyl compound unit in the polymer. Further, in the present invention, another invention is an injection molded product, an extrusion molded product, and a foamed product using the above rubber-modified styrene resin composition. It relates to molded articles.

[0005]

DETAILED DESCRIPTION OF THE INVENTION A detailed description will be given below. The rubber-modified styrenic resin (A) used in the present invention is one or more styrenic monomers in the presence of a rubber-like polymer, or one or two or more styrenic monomers and co-polymerization therewith. It is a rubber-modified styrene resin obtained by polymerizing with a polymerizable compound.

Examples of the (A) styrene monomer as a raw material of the rubber-modified styrene resin used in the present invention include styrene, α-alkyl-substituted styrene such as α-methylstyrene, and nucleus such as p-methylstyrene. Substituted alkyl styrene and the like can be mentioned. Examples of the compound copolymerizable with the styrene-based monomer include vinyl monomers such as acrylonitrile, methacrylonitrile, methacrylic acid and methyl methacrylate, and maleic anhydride, maleimide, and nucleus-substituted maleimide.
Further, as the rubber-like polymer, for example, polybutadiene,
Styrene-butadiene copolymers, ethylene-propylene-non-conjugated diene terpolymers and the like are used,
Among them, polybutadiene and styrene-butadiene copolymers are most preferable. As the polybutadiene, both high cis polybutadiene having a high cis content and low cis polybutadiene having a low cis content can be used.

The content of the soft component particles in the rubber-modified styrene resin (A) used in the present invention is 5 to 35% by weight. If the content of the soft component particles is less than 5% by weight, the composition containing the resin is inferior in impact strength, and if it is more than 35% by weight, the rigidity is inferior. In the present invention, the content of the soft component particles in the rubber-modified styrene resin (A) is measured by the following method. That is, about 0.5 g of a rubber-modified styrene resin as a sample was weighed (weight: W ₁ ) and sampled at room temperature (about 23 ° C.) in a methyl ethyl ketone / methanol mixed solvent (volume ratio 10/1) 50 m.
Dissolve in 1. Next, the insoluble matter at the time of dissolution is isolated by centrifugation, the insoluble matter is dried, and its weight (W ₂ ) is measured. The content of the soft component particles in the rubber-modified styrene resin is calculated by (W ₂ / W ₁ ) × 100 (%). The average particle size of the soft component particles is 0.1 to 2.
It is 5 μm, preferably 0.1 μm to 2 μm. When the average particle size of the soft component particles is less than 0.1 μm, the composition containing the resin is inferior in impact strength, and when it is larger than 2.5 μm, the rigidity and the appearance are inferior. The average particle size is defined as follows. An ultrathin section of rubber-modified styrene resin was prepared, a transmission electron microscope photograph was taken, and the soft component particle diameter in the photograph was measured.

[0008]

## EQU00001 ## Average particle size = .SIGMA. (Ni.Di) /. SIGMA.ni where ni is the number of particles having a particle size Di. In the present invention, the soft component particles in the rubber-modified styrenic resin (A) are, for example, a core portion which is a single continuous phase consisting of a styrene resin alone and an inclusion (occlude) of the core portion.
Occluded) having a single occlusion structure (also referred to as a core / shell structure or a capsule structure) composed of a shell portion made of a rubbery polymer, or a plurality of styrenic compounds in a continuous phase made of a rubbery polymer. Examples thereof include those having a so-called salami structure in which small resin particles are present in a dispersed state, but the structure is not particularly limited. The structure of the soft component particles is observed by using a transmission electron microscope as in the above-mentioned measurement of the average particle size.

The swelling degree of the soft component particles in the rubber-modified styrene resin (A) used in the present invention is 3 to 30,
It is preferably 8 to 20. When the degree of swelling is less than 3, the composition containing the resin is inferior in impact strength, and when the degree of swelling is more than 30, the composition is inferior in rigidity, which is not preferable in practice. The degree of swelling of the soft component particles of the rubber-modified styrene resin (A) of the present invention is determined by the following method. That is, about 1.0 g of a rubber-modified styrenic resin, which is a sample, is dissolved in 50 ml of toluene at room temperature and left for one day. The obtained toluene solution is centrifuged (10000 rpm × 30 minutes) to separate the insoluble matter. The supernatant liquid is discarded, the insoluble matter is weighed, and the weight is defined as a. Next, the insoluble matter is dried with a vacuum dryer (70 ° C. × 3 hours), and the weight after drying is set to b. The degree of swelling is calculated by (ab) / b. As the method for producing the rubber-modified styrene resin (A) used in the present invention, a bulk polymerization method or a bulk / suspension two-stage polymerization method is used. Then, the rubber-like polymer concentration during the polymerization reaction, the stirring speed, by adjusting the temperature, etc., required in the present invention, the content of the soft component particles, the average particle diameter of the particles,
It is possible to obtain a rubber-modified styrene resin that satisfies the conditions such as the degree of swelling.

Next, in the present invention, a polymer (B) having a solubility parameter (SP) of 8.45 to 8.70 and containing no aromatic vinyl compound unit is added to the composition (A) rubber-modified styrene type. More than 10 parts by weight and not more than 250 parts by weight based on 100 parts by weight of resin, but the content is 10
If it is less than 50 parts by weight, the impact strength and oil resistance are insufficient,
If the amount is more than the weight part, other physical properties such as rigidity are deteriorated, which is not preferable. The content of the component (B) in the composition of the present invention is converted from the area ratio of the component (B) occupying in the photograph by making an ultrathin section of the composition and taking a transmission electron micrograph of the composition. You can ask. In addition, NMR and IR
It is possible to use a method of determining from the absorption peak using a spectroscope such as, a method of separating with a solvent, and the like. Further, the solubility parameter (SP) of the component (B) of the present invention is 8.45 to 8.70, and if it is smaller than 8.45 or larger than 8.70, the effect of improving impact strength is not sufficient. The solubility parameter here means Hildebr
The attraction force between molecules is defined by the And-Scatchard theory. For detailed explanations, refer to general textbooks on polymer science, such as "Polymer Blend, Saburo Akimoto et al., CMC, 4th edition, 125-14.
4 page (1991) ”, etc. However, this solubility parameter can be obtained by experiments such as the viscosity method or the swelling method, or by calculation from the molecular structure. No, so Small
Here, the method of calculating from the molecular structure proposed by the author was used. This method and theory
Of Applied Chemistry (Journal o
f Applied Chemistry), Volume 3, 7
1-80 (1953) ".
Thus, the solubility parameter was calculated using the following formula.

[0011]

[Equation 2] Fi is a molar attraction force of a constituent group such as an atom or an atomic group constituting a molecule, a bond type, V is a molar volume, ρ is a density, and M is a molecular weight. Indicates. As the value of Fi, the value of Small described in the above two documents was used. For ρ, ΣFi or M of the copolymer, calculate the sum of the values of ρ, ΣFi or M of each homopolymer of the monomer units constituting the copolymer, and multiply the mole fraction of the monomer units by I was there. The component (B) of the present invention is a polymer containing no aromatic vinyl compound unit in the polymer. A composition using a polymer containing an aromatic vinyl compound unit has poor impact strength. Examples of the aromatic vinyl compound include α-alkyl-substituted styrenes such as styrene and α-methylstyrene, and nuclear-substituted alkylstyrenes such as p-methylstyrene. Further, the solubility parameter (SP) of the component (B) used in the present invention is 8.45.
As the polymer having a viscosity of up to 8.70, one of unsaturated carboxylic acid, unsaturated carboxylic acid ester or vinyl acetate can be used.
Examples thereof include copolymers of one or more vinyl monomers and ethylene. Examples thereof include ethylene-unsaturated carboxylic acid copolymers, ethylene-unsaturated carboxylic acid ester copolymers, ethylene-vinyl acetate copolymers, ethylene-unsaturated carboxylic acid ester-vinyl acetate terpolymers, ethylene. And a multi-component copolymer composed of two or more kinds of unsaturated carboxylic acid esters.

Specific examples of unsaturated carboxylic acids include acrylic acid and methacrylic acid. Specific examples of the unsaturated carboxylic acid ester include ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate,
Examples thereof include 2-ethylhexyl methacrylate, stearyl methacrylate, and glycidyl methacrylate.
Preferred examples of the copolymer of ethylene with one or more vinyl monomers of unsaturated carboxylic acid, unsaturated carboxylic acid ester or vinyl acetate used in the present invention include ethylene-acrylic acid copolymer and ethylene-methacrylic acid. Copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-vinyl acetate, ethylene-methyl acrylate-glycidyl methacrylate copolymer Coalescing,
Examples thereof include ethylene-methyl methacrylate-glycidyl methacrylate copolymer and ethylene-vinyl acetate-glycidyl methacrylate copolymer. The proportion of the vinyl monomer unit in the copolymer is preferably 5 to 60% by weight. Further, there is no limitation on the binding mode (for example, random, block, alternating) of the vinyl monomer and ethylene in the copolymer. The melt flow rate of the copolymer (according to JIS K7210, temperature 190
(° C, load 2.16 kgf) is not particularly limited, but is preferably about 1 to 500 g / 10 minutes.

To obtain the rubber-modified styrenic resin composition of the present invention, a predetermined amount of each component is dry blended with a mixing device such as a Henschel mixer or a tumbler, or a uniaxial or biaxial screw extruder, a Banbury mixer. A kneading machine such as the above may be used to sufficiently heat and knead at a temperature of 180 to 260 ° C., and then granulate. Note that additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, mineral oil, and silicone oil can be used as needed. These additives may be added during the above dry blending or kneading, but may be added during the polymerization step when the rubber-modified styrene resin is synthesized by polymerization.

The injection-molded article using the rubber-modified styrene resin composition of the present invention can be obtained by using a generally used injection molding machine.

The extrusion molded article using the rubber-modified styrene resin composition of the present invention can be obtained by using a generally used extrusion molding machine. The method of extruding the rubber-modified styrenic resin composition of the present invention into an extruded molded article is not particularly limited, but for example, it is melted by an extruder and then extruded from a T-die, or formed into a sheet by an extruder. After extrusion, a method of biaxially stretching by a tenter system or an inflation system can be used.

The method for foaming the rubber-modified styrenic resin composition of the present invention to form a foam is not particularly limited, but, for example, a decomposable foaming agent and the rubber-modified styrenic resin composition are melted by an extruder. Method of kneading and foaming; melting the rubber-modified styrene-based resin composition with an extruder,
Evaporative foaming agent is directly pressed in the middle of the cylinder, kneading,
A method of foaming; a method of impregnating small pellets or beads made of a rubber-modified styrene resin composition with an evaporative foaming agent in an extruder or an aqueous suspension, and foaming the impregnated pellets or beads with steam. To be Examples of the decomposition type foaming agent used here include azodicarbonamide, trihydrazinotriazine, and benzenesulfonyl semicarbazide. Examples of evaporative foaming agents include propane, n-butane, i-butane, n-pentane, i-pentane, hexane, heptane, freon and the like.

The rubber-modified styrenic resin composition of the present invention is suitable for use in the fields of injection molded processed products, extruded sheet processed products and foam molded processed products. That is, specific applications include exterior materials for light electric appliances, office equipment, telephones, office automation equipment, and packaging materials such as food containers. In addition, a foam obtained by foaming a resin composition can be used as a so-called cushioning material that absorbs external impact applied to glass products and various precision equipment products and protects the products.

[0018]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. The measurement and evaluation methods are as follows. (1) Molding processability (presence or absence of bumps) <Injection molding> Using IS-150E manufactured by Toshiba, mold temperature 4
Flat plate injection molding was performed at 0 ° C. and a sample shape of 150 × 90 × 2 mm. At that time, the resin was retained in the cylinder at 240 ° C. for 1 hour and then injection-molded, and the presence or absence of hits on the flat plate surface was visually evaluated. <Extrusion Molding> A sheet processing machine having a thickness of 0.6 mm was extruded at a resin temperature of 240 ° C. using a sheet processing machine of 65 mmφ (Tanabe Plastic Machinery Co., Ltd., V65-S1000 type). At that time, put the resin in the cylinder at 240 ° C for 1
The sheet was extruded after being retained for a period of time, and the presence or absence of bumps on the sheet surface was visually evaluated.

(2) Oil resistance The resin composition is preheated at 210 ° C. for 5 minutes and then 50 kg.
/ Cm ² and 150 mm x 150 mm under pressure for 5 minutes
× 3mm press sheet is formed, then 20mm ×
A 150 mm × 3 mm test piece was cut out and used for measurement. Oil resistance is measured by fixing one end of the test piece to a jig,
Margarine (Neosoft manufactured by Snow Brand Milk Products Co., Ltd.) was applied to the surface of the test piece in a state of being distorted by 10 mm at a position of 100 mm from the fixed position, and allowed to stand at room temperature for 24 hours. evaluated.
No stress cracks were evaluated as ◯, and stress cracks were evaluated as x. (3) Impact strength of falling weight A flat plate with a thickness of 2 mm is injection-molded and a weight of 7.5 kg from a height of 80 cm is placed on the surface of the test piece using a "falling weight type graphic impact tester" from Toyo Seiki Seisakusho. The test piece is allowed to fall naturally and the test piece is completely broken or penetrated by a striker provided below the weight. The energy required for this was calculated. The measurement temperature was 23 ° C. The molding machine used was IS-150E manufactured by Toshiba, and the mold temperature was 40 ° C. and the sample shape was 150 mm × 90 mm × 2 mm.

(4) Izod impact strength A test piece obtained by injection molding was JIS K71.
It measured according to 10. The thickness of the test piece is 3.0m
m, notched, and the measurement temperature was 23 ° C. (5) Gloss (surface appearance) A flat plate with a thickness of 2 mm is injection molded, and the central part is JIS
It was measured according to the standard of K7105 45 degree specular gloss measurement method. Toshiba IS-150E was used as the molding machine, the mold temperature was 40 ° C., and the sample shape was 150 mm × 90 m.
It was set to m × 2 mm. (6) Bending elastic modulus (rigidity) A test piece obtained by injection molding was JIS K72.
It measured based on 03. The measurement temperature was 23 ° C.

Examples 1 to 7 and Comparative Examples 1 to 8 The components shown in Tables 1, 2 and 3 were melted at 220 ° C. in a 40 mmφ extruder, kneaded and granulated to obtain pellets. The obtained pellets were injection-molded into a test piece or a flat plate or press-molded and evaluated. Also, dry blending the components shown in Tables 1, 2 and 3,
Extrusion was performed using an extrusion sheet processing machine, and the molding processability was evaluated. The (A) rubber-modified styrene resin used was
It was synthesized by the continuous bulk polymerization method as follows, and its structure is shown in Table 4. A1: A mixed solution of 80% by weight of styrene, 12% by weight of styrene-butadiene block copolymer (40% by weight of styrene), 5% by weight of ethylbenzene and 3% by weight of mineral oil was fed to a stirring type polymerization tank, Temperature 140
Polymerization was carried out under the conditions of ℃ and stirring speed of 35 rpm up to a conversion rate of 37.5%. Subsequently, the obtained mixed liquid was transferred to a full-filling type polymerization tank where polymerization was performed up to a conversion rate of 77%, and then the content was transferred to a degassing tank at 240 ° C. to remove volatile components, and then obtained. The polymer was passed through a melt extruder and a pelletizer to obtain pelletized rubber-modified styrene resin. A2: 89.8% by weight of styrene, 5.6% by weight of polybutadiene, and 3.6% by weight of ethylbenzene in a stirring type polymerization tank.
And a mixed solution consisting of 1% by weight of mineral oil,
Conversion rate 2 under conditions of temperature 140 ° C and stirring speed 60 rpm
Polymerized to 3%. Subsequently, the obtained mixed liquid was transferred to a full-filling type polymerization tank where polymerization was performed up to a conversion rate of 70%, and then the content was transferred to a degassing tank at 240 ° C. where volatile components were removed and then obtained. The polymer was passed through a melt extruder and a pelletizer to obtain pelletized rubber-modified styrene resin. A3: 88.3% by weight of styrene, 5.4% by weight of polybutadiene, and 3.9% by weight of ethylbenzene in a stirring type polymerization tank.
A mixed solution consisting of 2.41% by weight of mineral oil and 2.41% by weight of mineral oil was fed and polymerized to a conversion of 17% under the conditions of a temperature of 140 ° C. and a stirring speed of 45 rpm. Subsequently, the obtained mixed solution was transferred to a full-filling type polymerization tank where polymerization was performed up to a conversion rate of 71%, and then the content was transferred to a degassing tank at 240 ° C. to remove volatile components, and then obtained. The polymer was passed through a melt extruder and a pelletizer to obtain pelletized rubber-modified styrene resin.

The components (B) used are as follows. B1: Ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Acrif WM403, methyl methacrylate content 38% by weight, melt flow rate 15 g)
/ 10 minutes), B2: ethylene-ethyl acrylate copolymer (ethyl acrylate content 18% by weight, melt flow rate 7 g)
/ 10 minutes), B3: ethylene-vinyl acetate copolymer (Sumitomo Chemical Co., Ltd., trade name Summitate RB-11, vinyl acetate content 41)
% By weight, melt flow rate 60 g / 10 minutes), B4: polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name Nobren AD571, melt flow rate 0.2 g / 10)
Min), B5: polyethylene (Sumitomo Chemical Co., Ltd., trade name Sumikasen α FZ103-0, melt flow rate 0.9 g /
10 minutes), B6: styrene-methyl methacrylate copolymer (Nippon Steel Chemical Co., Ltd., trade name Estyrene MS200, methyl methacrylate content 20% by weight, melt flow rate 0.
2 g / 10 minutes), B7: ethylene-methyl methacrylate copolymer (Sumitomo Chemical Co., Ltd., trade name Acryft WK402, methyl methacrylate content 25% by weight, melt flow rate 20 g)
/ 10 minutes) The melt flow rate was measured according to JIS K7210 at a temperature of 190 ° C. and a load of 2.16 kgf. The solubility parameters (SP) of these components (B) are shown in Table 5.

The following can be seen from the results. Molded articles made from the compositions of the examples of the present invention are excellent in impact strength and oil resistance. On the other hand, Comparative Examples 1, 5 to 7 in which the amount of the component (B) is small
The ones are inferior in oil resistance and impact strength. Those of Comparative Examples 2 to 4 in which SP has a polymer outside the specified range as the component (B) have poor impact strength. The thing of Comparative Example 8 which does not contain (B) component but contains (C) component is inferior in moldability and oil resistance.

[0024]

[Table 1] * 1: (A) Rubber-modified styrene resin * 2: (B) Polymer shown in Table 5

[0025]

[Table 2] * 1: (A) Rubber-modified styrene resin * 2: (B) Polymer shown in Table 5

[0026]

[Table 3] * 1: (A) rubber-modified styrene resin * 2: (B) polymer shown in Table 5 * 3: (C) styrene-butadiene-styrene block copolymer (C1: butadiene content = 60%, manufactured by Asahi Kasei,
Product name Toughplane A)

[0027]

[Table 4]

[0028]

[Table 5]

Claims (9)

[Claims] 1. To 100 parts by weight of the following component (A),
A rubber-modified styrene-based resin composition containing (B) component in an amount of more than 10 parts by weight and 250 parts by weight or less. (A): Rubber modification containing 5 to 35% by weight of soft component particles, having an average particle size of the soft component particles of 0.1 to 2.5 μm, and a swelling degree of the soft component particles of 3 to 30. Styrenic resin (B): solubility parameter (SP) is 8.45 to 8.7.
A polymer which is 0 and does not contain an aromatic vinyl compound unit in the polymer. 2. The component (B) is a copolymer composed of ethylene and at least one vinyl monomer selected from unsaturated carboxylic acids, unsaturated carboxylic acid esters or vinyl acetate.
The resin composition as described in the above. 3. The resin composition according to claim 1, wherein the component (B) is an ethylene-unsaturated carboxylic acid ester copolymer. 4. The resin composition according to claim 1, wherein the component (B) is an ethylene-methyl methacrylate copolymer. 5. The resin composition according to claim 1, wherein the component (B) is an ethylene-vinyl acetate copolymer. 6. The resin composition according to claim 1, wherein the component (B) is a copolymer composed of ethylene and two or more different unsaturated carboxylic acid esters. 7. An injection-molded article using the rubber-modified styrene resin composition according to claim 1, claim 2, claim 3, claim 4, claim 5 or claim 6. 8. An extrusion molded product using the rubber-modified styrene resin composition according to claim 1, claim 2, claim 3, claim 4, claim 5 or claim 6. 9. A foam-molded article using the rubber-modified styrene resin composition according to claim 1, claim 2, claim 3, claim 4, claim 5 or claim 6.