JP3141751B2 - Rubber-modified styrenic resin composition and molded article thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-modified styrenic resin composition having excellent surface impact strength and a molded product thereof. More particularly, the present invention relates to a rubber composition having improved surface impact strength. The present invention relates to a rubber-modified styrenic resin composition whose physical properties have not been reduced and a molded article thereof.

[0002]

2. Description of the Related Art In application fields such as OA equipment and home electric appliances, it is necessary to have a good balance of workability at the time of molding, finished dimensional accuracy of the processed product, mechanical properties such as tension and bending, and physical properties such as heat resistance. Although it is required, improvement of impact strength is further demanded especially because of the exterior material. Such demands have reached an increasingly high level in recent years. Also, when used as a packaging material, a high level of impact strength and appearance are required. When used as a cushioning material, one of the essential properties to be provided is that it has excellent shock absorption. However, the rubber-modified styrenic resin composition is not necessarily satisfactory in view of sufficiently satisfying all the above requirements. As a technique for improving the impact resistance of a rubber-modified styrenic resin, there is known a method of adding a specific amount of an organic polysiloxane and an ethylene-unsaturated carboxylic acid ester copolymer as disclosed in JP-B-3-41104. ing. However, the organic polysiloxane is an essential component, and it has been troublesome and expensive to add.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to provide an excellent impact strength by adding a relatively small amount of a blend, and to be excellent in moldability and other physical properties. Another object of the present invention is to provide a rubber-modified styrenic resin composition excellent in performance required for a foamed molded article and a molded article thereof.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have reached the present invention. That is, one invention of the present invention comprises 100 parts by weight of the following component (A) and 0.1 to 10 parts of the component (B).
It relates to a rubber-modified styrenic resin composition containing parts by weight. (A): a soft component particles contained 5 to 35% by weight, an average particle diameter of the soft quality component particles 0.5 to 2.5 .mu.m, swelling degree of soft matter component particles is 3 to 30, wherein Soft ingredient grains
Rubber-modified styrene-based resin having a salami structure as a child (B): solubility parameter (SP) is 8.45 to 8.7
0, and a polymer containing no aromatic vinyl compound unit in the polymer (except for the ethylene-unsaturated carboxylic acid ester copolymer). The present invention relates to an injection molded article, an extrusion molded article, or a foam molded article using the resin composition. The details will be described below.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber-modified styrenic resin (A) used in the present invention comprises one or more styrene-based monomers, or one or more styrene-based monomers in the presence of a rubbery polymer. A rubber-modified styrenic resin obtained by polymerizing a monomer and a compound copolymerizable therewith.

The styrene monomer which is a raw material of the rubber-modified styrene resin (A) used in the present invention includes, for example, nuclei such as α-alkyl-substituted styrene such as styrene and α-methylstyrene, and p-methylstyrene. And substituted alkylstyrene. Examples of the compound copolymerizable with the styrene monomer include vinyl monomers such as acrylonitrile, methacrylonitrile, methacrylic acid, and methyl methacrylate, as well as maleic anhydride, maleimide, and a nucleus-substituted maleimide.
Further, as the rubbery 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 preferred. As 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) of the present invention is 5 to 35% by weight. If the content is less than 5% by weight, the impact strength is not sufficiently improved, and if it exceeds 35% by weight, physical properties other than the impact strength, for example, rigidity and heat resistance are undesirably reduced. In addition,
In the present invention, the content of the soft component particles in the rubber-modified styrene resin (A) is measured by the following method. Specifically, about 0.5 g of a rubber-modified styrene resin as a sample was weighed (weight: W ₁ ), and the sample was dissolved in 50 ml of a methyl ethyl ketone / methanol mixed solvent (volume ratio: 10/1) at room temperature (about 23 ° C.). Let it. Next, the insoluble matter at the time of the 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 (W ₂ / W ₁ ) × 10
It is determined by 0 (%). The average particle diameter of the soft component particles is 0.1 to 2.5 μm. This is 0.1 μm
If it is less than 2.5 μm, the surface impact strength is not sufficiently improved, and if it is more than 2.5 μm, the appearance such as gloss decreases, which is not preferable. Here, the average particle diameter is defined as follows. That is, an ultra-thin section of a rubber-modified styrene resin is prepared, a transmission electron micrograph thereof is taken, the particle diameter of the soft component in the photograph is measured, and it is calculated by the following equation.

[0008]

[Equation 1] Average particle size = ΣniDi / Σni where ni is the number of particles having a particle size Di.

[0009] In the present invention, (A) the soft component particles children in the rubber-modified styrenic resin, the small particles of a plurality of the styrene resin in a continuous phase consisting of rubber-like polymer is present in a dispersed, so-called salami It also has a structure. The observation of the structure of the soft component particles is performed using a transmission electron microscope as in the measurement of the average particle diameter described above. The swelling degree of the soft component particles in the rubber-modified styrenic resin (A) of the present invention is 3 to 30, preferably 8 to 20. 3 degree of swelling
If less than the composition containing the resin is inferior in impact strength,
If it is larger than 30, the rigidity and appearance are inferior, which is not practically preferable. The degree of swelling of the soft component particles of the rubber-modified styrene resin (A) of the present invention can be determined by the following method. That is, about 1.0 g of a rubber-modified styrene resin as a sample
Is dissolved in 50 ml of toluene at room temperature and left overnight. The obtained toluene solution is centrifuged (10000 r).
pm × 30 minutes) to separate insoluble matter. The supernatant is discarded, the insoluble matter is weighed, and the weight is defined as a. next,
The insolubles were dried with a vacuum dryer (70 ° C. × 3 hours),
Let b be the weight after drying. The degree of swelling is determined by (ab) / b. The method for producing the rubber-modified styrenic resin (A) used in the present invention may be a bulk polymerization method or a bulk polymerization method.
A suspension two-stage polymerization method is used. Then, by adjusting the rubber-like polymer concentration during the polymerization reaction, stirring speed, temperature and the like, the content of the soft component particles required in the present invention,
A rubber-modified styrenic resin that satisfies the conditions such as the average particle size and swelling degree of the particles can be obtained.

Next, in the present invention, a polymer having (B) a solubility parameter (SP) of 8.45 to 8.70 and containing no aromatic vinyl compound unit in the composition is an ethylene-unsaturated carboxylic acid ester. (A) excluding the copolymer
0.1 to 100 parts by weight of rubber-modified styrenic resin
Although the content is 10 parts by weight, if the content is less than 0.1 part by weight, the effect of improving the impact strength is not sufficient, and if the content is more than 10 parts by weight, other physical properties such as heat resistance deteriorate, which is not preferable. In addition,
The content of the component (B) in the composition of the present invention is determined by preparing an ultrathin section of the composition, taking a transmission electron micrograph, and converting the area ratio of the component (B) in the photograph. You can ask. In addition, a method of obtaining from the absorption peak using a spectroscope such as NMR or IR, a method of performing fractionation using a solvent, and the like can be used. The solubility parameter (SP) of the component (B) of the present invention is 8.45 to
When it is 8.70, and is smaller than 8.45 or larger than 8.70, the effect of improving the impact strength is not sufficient. Here, the solubility parameter is Hildebrand-Sc.
Attraction's theory defines the attractive force between molecules. Detailed explanations are given in general textbooks of polymer science such as "Polymer Blend, Saburo Akimoto et al.
CMC Co., Ltd., 4th printing, pages 125-144 (19
However, the solubility parameter includes a method obtained by experiments such as a viscosity method and a degree of swelling method and a method obtained by calculation from a molecular structure, and the value is slightly different depending on the method. The method used by calculation from the molecular structure proposed by Small, Inc., was used here.This method and theory is described in the Journal of Applied Chemistry (Journal of Applied Chemistry).
Lied Chemistry, Vol. 3, pages 71-80 (1953) ", whereby the solubility parameter was calculated using the following equation.

[0011]

(Equation 2) Fi is the molar attractive force of the constituent groups such as atoms or atomic groups constituting the molecule, bond type, etc., V is the molar volume, ρ is the density, M is the molecular weight. In the case of a polymer, the molecular weight of a repeating unit (that is, monomer unit) Is shown. As the value of Fi, the value of Small described in the above two documents was used. For ρ, ΔFi or M of the copolymer, the sum of the values of ρ, ΔFi or M of each homopolymer of the monomer units constituting the copolymer multiplied by the mole fraction of the monomer units is used. Was. The component (B) used in the present invention is a polymer containing no aromatic vinyl compound unit in the polymer. A composition using a polymer having an aromatic vinyl compound unit in the polymer 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. Although the component (B) used in the present invention does not contain an ethylene-unsaturated carboxylic acid ester copolymer, examples of the ethylene-unsaturated carboxylic acid ester copolymer include an ethylene-methyl methacrylate copolymer, Examples include an ethylene-ethyl methacrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methyl acrylate copolymer. Further, the meltability parameter (SP) of the component (B) used in the present invention is 8.45 to 8.70.
Examples of the polymer are copolymers of ethylene with one or more vinyl monomers of unsaturated carboxylic acid or vinyl acetate. Examples thereof are ethylene-unsaturated carboxylic acid copolymer, ethylene-vinyl acetate copolymer,
Examples include an ethylene-unsaturated carboxylic acid-vinyl acetate terpolymer, and a multi-component copolymer composed of ethylene and two or more kinds of unsaturated carboxylic acids.

Specific examples of the unsaturated carboxylic acid include acrylic acid and methacrylic acid. Preferred examples of the copolymer of ethylene and one or more vinyl monomers of the unsaturated carboxylic acid or vinyl acetate used in the present invention include ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene- Vinyl acetate, ethylene-
Acrylic acid-vinyl acetate copolymer, ethylene-methacrylic acid-vinyl acetate copolymer and the like can be mentioned. The ratio of unsaturated carboxylic acid units or vinyl acetate units in the copolymer is 5
~ 60% by weight is preferred. Further, there is no particular limitation on the bonding mode (for example, random, block, alternate) between the vinyl monomer and ethylene in the copolymer. The melt flow rate of the copolymer (according to JIS K7210, at a temperature of 190 ° C. and a load of 2.16 kgf) is not particularly limited, but is preferably about 1 to 500 g / 10 minutes.

In order 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 single-screw or twin-screw extruder, a Banbury mixer The mixture may be sufficiently heated and kneaded at a temperature of 180 to 260 ° C. using a kneader such as the above, followed by granulation. 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 at the time of the above-mentioned dry blending or kneading, but may be added at the polymerization step when the rubber-modified styrene resin is synthesized by polymerization.

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

An extruded product using the rubber-modified styrenic resin composition of the present invention can be obtained by using a generally used extruder. The method for extruding the rubber-modified styrenic resin composition of the present invention to obtain an extruded product is not particularly limited. For example, a method of extruding from a T-die after melting with an extruder, After extruding into a sheet, biaxial stretching may be performed by a tenter method or an inflation method.

The method of foaming the rubber-modified styrenic resin composition of the present invention to form a foam is not particularly limited. For example, a dispersion-type foaming agent and the rubber-modified styrenic resin composition are melt-kneaded by an extruder. A method in which a rubber-modified styrene-based resin composition is melted by an extruder and an evaporating foaming agent is directly press-fitted from the middle of a cylinder, kneaded and foamed; small pellets or beads made of the rubber-modified styrene-based resin composition Impregnated with an evaporating foaming agent in an extruder or an aqueous suspension, and foaming the impregnated pellets or beads with steam.

The rubber-modified styrenic resin composition of the present invention is suitably used in the fields of injection-molded products, extruded sheet products, and foam-formed products, taking advantage of its features. That is, specific applications include exterior materials such as light electrical appliances, office equipment, telephones, and OA appliances, 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]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The measurement and evaluation methods are as follows. In addition,
Items other than those described below were performed as described above. (1) Flexural modulus (rigidity) Measured according to JIS K7203. (2) Vicat softening point (heat resistance) Measured according to JIS K7206, B method. (3) Drop Weight Impact A flat plate having a thickness of 2 mm is injection molded, and a weight of 7.5 kg in mass from a height of 80 cm is naturally placed on the plane of the test piece using a “drop weight type graphic impact tester” manufactured by Toyo Seiki Seisaku-sho, Ltd. The specimen is dropped, and the test piece is completely broken or penetrated by a striker provided below the weight. The energy value required for crack generation at this time was determined. The molding machine is Toshiba IS
Using -150E, mold temperature 40 ° C, sample shape 15
It was set to 0 × 90 × 2 mm. (4) Izod impact strength Measured according to JIS K7110. The test piece had a thickness of 3 mm, a notch, and a measurement temperature of 23 ° C. (5) Surface 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. The molding machine used was Toshiba IS-150E,
The mold temperature was 40 ° C. and the sample shape was 150 × 90 × 2 mm. In addition, the measurement was similarly performed for the resin sheet.

Examples 1 to 3 and Comparative Examples 1 to 6 The components shown in Tables 1 and 2 were extruded by a 40 mmφ extruder.
The mixture was melted at 20 ° C., kneaded and granulated to obtain pellets. The obtained pellet was injection molded into a test piece or a flat plate and evaluated. The rubber-modified styrenic resin (A) used was synthesized by a continuous bulk polymerization method as follows. A1: A mixed solution composed of 92.5% by weight of styrene, 4% by weight of polybutadiene and 3.5% by weight of ethylbenzene was sent to a stirring-type polymerization tank at a temperature of 140 ° C. and a stirring speed of 45 r.
Under a condition of pm, polymerization was carried out up to a conversion rate of 21%. continue,
The obtained mixture was transferred to a full-type polymerization tank, where the conversion rate was 7%.
0%, then the contents are transferred to a degassing tank at 240 ° C. to remove volatile components therefrom, and then the obtained polymer is passed through a melt extruder and a pelletizer to pelletize rubber-modified styrene resin. Obtained. A2: A mixed solution composed of 88% by weight of styrene, 7% by weight of polybutadiene, 3.5% by weight of ethylbenzene and 1.5% by weight of mineral oil was sent to a stirring-type polymerization tank at a temperature of 140 ° C. and a stirring speed of 40 rpm. 18% conversion rate
The polymerization was carried out until: Subsequently, the obtained mixed solution was transferred to a full polymerization tank where polymerization was performed to a conversion rate of 70%, and then the contents were transferred to a deaeration tank at 240 ° C. to remove volatile components, and then obtained. The polymer was passed through a melt extruder and a pelletizer to obtain a pelletized rubber-modified styrene resin. The components (B) used are as follows. B1: Ethylene-vinyl acetate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumitate RB-11, vinyl acetate content 41)
B2: Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Noblen AD571 (melt flow rate: 0.2 g / 10 min.)
B3: Polyethylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikasen α FZ103-0 (melt flow rate 0.9 g /
B4: Polymethyl methacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: SUMIPEX-BMHG, melt flow rate: 0.1%).
B5: Styrene-acrylonitrile copolymer (manufactured by Mitsubishi Monsanto Kasei, trade name Sunlex SAN-C, acrylonitrile content 33% by weight, melt flow rate 0.5)
g / 10 minutes). The melt flow rate was measured at a temperature of 190 ° C. and a load of 2.16 kgf according to JIS K7210. Table 3 shows the solubility parameter (SP) of the component (B). As silicone oil, Toray silicone silicone oil, SH200 (1000 centistokes)
Was used.

The following can be seen from the results. In Table 1, Example 1 of the present invention is excellent in impact strength. on the other hand,
Comparative Example 1 containing no component (B) is inferior in impact strength. S
Comparative Examples 2 to 5, in which P contains a polymer out of the specified range as the component (B), are inferior in impact strength. Comparative Example 5, which contains a polymer containing an aromatic vinyl compound unit in the polymer as the component (B), is inferior in impact strength. In Table 2, Examples 2 and 3 of the present invention are excellent in impact strength. On the other hand, Comparative Example 6 containing no component (B) is inferior in impact strength.

[0021]

[Table 1]

[0022]

[Table 2]

The following notes are common to Tables 1 and 2. * 1 (A): Rubber-modified styrene resin (styrene was used as the styrene monomer) * 2 (B): Polymer shown in Table 3 * 3 (C): Silicon oil * 4 SAL: Salami Construction

[0024]

[Table 3]

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08L 23:08) B29K 96:02 (56) References JP-A-3-220255 (JP, A) JP-A 8-151500 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 51/04 B29C 39/02 B29C 45/00 B29C 47/00 C08L 23/08 B29K 96:02

Claims (6)

(57) [Claims] (1) 100 parts by weight of the following component (A):
A rubber-modified styrenic resin composition containing 0.1 to 10 parts by weight of the component (B). (A): a soft component particles contained 5 to 35% by weight, an average particle diameter of the soft quality component particles 0.5 to 2.5 .mu.m, swelling degree of soft matter component particles is 3 to 30, wherein Soft ingredient grains
Rubber-modified styrene-based resin having a salami structure as a child (B): solubility parameter (SP) is 8.45 to 8.7
0 and a polymer containing no aromatic vinyl compound unit in the polymer (excluding an ethylene-unsaturated carboxylic acid ester copolymer) 2. The resin composition according to claim 1, wherein the component (B) is a copolymer comprising at least one vinyl monomer of unsaturated carboxylic acid or vinyl acetate and ethylene. 3. The resin composition according to claim 1, wherein the component (B) is an ethylene-vinyl acetate copolymer. 4. An injection-molded article using the rubber-modified styrene resin composition according to claim 2 or 3. 5. An extruded product using the rubber-modified styrene resin composition according to claim 1, 2 or 3. 6. A foam molded article using the rubber-modified styrene resin composition according to claim 1, 2 or 3.