JP2021101003A - Resin composition and molded body - Google Patents

Abstract

To provide a resin composition having a good balance of excellent moldability, a low molding shrinkage ratio, chemical resistance, and impact resistance.SOLUTION: A resin composition comprises: a styrene-based block copolymer; a styrene-based resin other than the styrene-based block copolymer; and a propylene-based resin having a melt flow rate (230°C, load 2.16 kgf) equal to or more than 3 g/10 min. The propylene-based resin is included in an amount of 35-65 mass% with respect to 100 mass% of the total of the styrene-based resin and the propylene-based resin.SELECTED DRAWING: None

Description

The present invention relates to resin compositions and molded articles.

Since propylene-based resin has a small specific gravity and is excellent in mechanical properties such as impact resistance and chemical resistance, the molded product of the propylene-based resin is used in household products, foods, agriculture, fisheries, medical fields, and industrial fields. , Used in various fields such as construction. However, since the molded product of the propylene resin has a large molding shrinkage rate, it is difficult to obtain dimensional stability, and there is a problem in that it is easily deformed.

In addition, styrene-based resin molded products have good molding processability, low molding shrinkage, and excellent dimensional stability. Therefore, by taking advantage of these characteristics, they can be used in foods, home appliances, industrial parts, household goods, etc. Widely used. However, the styrene-based resin molded product has a problem in that it is inferior in chemical resistance.

In order to solve the above problems, a resin composition in which a propylene-based resin and a styrene-based resin are mixed has been studied.
For example, although the resin composition is mainly composed of a styrene resin, Patent Document 1 contains a styrene resin, a propylene resin, an ethylene-α-olefin copolymer, and a styrene block copolymer rubber. The composition is described, and Patent Document 2 describes a composition containing a styrene-based resin, an olefin-based resin, and a block copolymer of a styrene-based monomer and a conjugated diene-based monomer.

Japanese Unexamined Patent Publication No. 2000-186177 JP-A-2002-249629

A molded product formed from a conventional resin composition, such as the compositions described in Patent Documents 1 and 2, has at least one physical characteristic of moldability, low molding shrinkage, chemical resistance, and impact resistance. It is not sufficient, and conventionally, if an attempt is made to improve this insufficient physical property, other physical properties are deteriorated. Therefore, there has not been a resin composition that can sufficiently satisfy these physical properties in a well-balanced manner.

The present invention has been made in view of the above, and an object of the present invention is to provide a resin composition having an excellent balance of moldability, low molding shrinkage, chemical resistance and impact resistance.

As a result of diligent studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved according to the following composition, and has completed the present invention.
A configuration example of the present invention is as follows.

[1] A styrene-based block copolymer, a styrene-based resin other than the styrene-based block copolymer, and a propylene-based resin having a melt flow rate (230 ° C., load 2.16 kgf) of 3 g / 10 minutes or more. Including
The propylene-based resin is contained in an amount of 35 to 65% by mass based on 100% by mass of the total of the styrene-based resin and the propylene-based resin.
Resin composition.

[2] The resin according to [1], wherein the ratio of the melt flow rate (200 ° C., load 5 kgf) of the propylene resin to the melt flow rate (200 ° C., load 5 kgf) of the styrene resin is 2 or more. Composition.

[3] The resin composition according to [1] or [2], wherein the melt flow rate (200 ° C., load 5 kgf) is 5 g / 10 minutes or more.

[4] The resin composition has a sea-island structure and has a sea-island structure.
The sea part contains the propylene resin,
Shimabe contains the styrene resin,
The resin composition according to any one of [1] to [3].

[5] A molded product of the resin composition according to any one of [1] to [4].

According to the present invention, it is possible to provide a resin composition (molded article) having an excellent balance of moldability, appearance, low molding shrinkage, chemical resistance and impact resistance. In particular, according to the present invention, it is possible to easily obtain a composition (molded article) having a low molding shrinkage rate and having an excellent appearance while maintaining or improving the physical characteristics of the propylene-based resin.

FIG. 1 is a photograph when bending strain is applied to a test piece in a chemical resistance test in an example. FIG. 2 is a scanning electron micrograph of the test piece obtained in Example 4. FIG. 3 is a scanning electron micrograph of the test piece obtained in Comparative Example 1.

≪Resin composition≫
The resin composition according to one embodiment of the present invention (hereinafter, also referred to as “the present composition”) is a styrene-based block copolymer, a styrene-based resin other than the styrene-based block copolymer, and a melt flow rate (hereinafter, also referred to as “the present composition”). Includes a styrene resin having a load of 2.16 kgf at 230 ° C. and a load of 3 g / 10 minutes or more.
The propylene-based resin is contained in an amount of 35 to 65% by mass with respect to a total of 100% by mass of the styrene-based resin and the propylene-based resin.
Since the molded product obtained by molding the present composition is also a composition, the following description regarding the composition includes the molded product unless otherwise specified.

<Propene resin>
The propylene-based resin is not particularly limited as long as the melt flow rate is within the above range, and may be any of a propylene homopolymer, a block copolymer, and a random copolymer, and the stereoregularity of these polymers is also particularly high. Not limited.
Among these, as the propylene-based resin, a composition exhibiting the above-mentioned effect can be easily obtained, and in particular, a composition having a small molding shrinkage ratio can be easily obtained even though it is a propylene-based resin composition. From the above viewpoints, a homopolymer of propylene is preferable.
The propylene-based resin may be used alone or in combination of two or more.

The copolymer can be obtained by copolymerizing propylene with a comonomer capable of copolymerizing with propylene, and examples of the comonomer include olefins such as ethylene, butene, penten, hexene, and octene, which are preferable. Is ethylene or 1-butene.
Two or more kinds of these comonomer may be used.
The amount of the comonomer used is usually 30% by mass or less, preferably 20% by mass or less, based on 100% by mass of all the monomers used in the synthesis of the copolymer.

The propylene-based resin may be obtained by synthesizing it by a conventionally known method, or a commercially available product may be used.

The melt flow rate (MFR) of the propylene resin measured at 230 ° C. and a load of 2.16 kgf based on ISO 1133 is excellent in balance due to moldability, low molding shrinkage, chemical resistance and impact resistance. In particular, it is 3 g / 10 minutes or more, preferably 7 g / 10 minutes or more, and more preferably 10 g, from the viewpoint that a composition satisfying the moldability and chemical resistance at an extremely high level can be easily obtained. / 10 minutes or more, more preferably 15 g / 10 minutes or more, more preferably 18 g / 10 minutes or more, particularly preferably 25 g / 10 minutes or more, preferably 120 g / 10 minutes or less, more preferably 70 g / 10 minutes or less. , More preferably 50 g / 10 minutes or less, and particularly preferably 40 g / 10 minutes or less.

The propylene-based resin has a ratio of the MFR of the propylene-based resin (200 ° C., load of 5 kgf) to the MFR of the following styrene-based resin (200 ° C., load of 5 kgf) (MFR of the propylene-based resin / MFR of the styrene-based resin). It is desirable that the resin is preferably 2 or more, more preferably 5 or more, and particularly preferably 10 or more.
By using a propylene-based resin that satisfies the above relationship, the following sea-island structure can be easily formed, and a composition (molded product) having a good balance of low molding shrinkage, chemical resistance and impact resistance, and excellent appearance. Can be easily obtained.

The Izod impact strength (23 ° C.) of the propylene resin measured based on ASTM D256 is preferably ² kJ / m 2 or more from the viewpoint that a composition having excellent impact resistance can be easily obtained. ..

The flexural modulus of the propylene resin measured based on ASTM D790 is preferably 1000 MPa or more from the viewpoint that a composition having excellent mechanical strength can be easily obtained.

The content of the propylene-based resin in the present composition is preferably 35 to 65% by mass, more preferably 40 to 60% by mass, based on 100% by mass of the total of the propylene-based resin and the styrene-based resin in the composition. %.
When the content of the propylene-based resin is within the above range, the above-mentioned effect is exhibited while maintaining or improving the physical properties of the propylene-based resin, and in particular, a composition satisfying a low molding shrinkage and chemical resistance at an extremely high level. You can easily get things.
When the content of the propylene-based resin is less than the above range, the composition is particularly inferior in chemical resistance, and when the content of the propylene-based resin is more than the above range, the composition has a particularly large molding shrinkage.

<Styrene block copolymer>
The styrene-based block copolymer is, for example, composed of a polymer block composed of a styrene-based monomer and a polymer block composed of a conjugated diene-based monomer or a conjugated diene-based monomer. Examples thereof include a block copolymer having a polymer block in which a part or all of the polymer block is hydrogenated.
The block copolymer may be used alone or in combination of two or more. Further, the block copolymer may be obtained by synthesizing it by a conventionally known method, or a commercially available product may be used.

Examples of the styrene-based monomer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dichlorostyrene, and 2,5-dichlorostyrene. , Styrene is preferred.
Examples of the conjugated diene-based monomer include butadiene, isoprene, piperylene, methylpentadiene, and phenyldiene, but butadiene or isoprene is preferable.

As the styrene-based block copolymer, hydrogenated additives of a styrene-butadiene block copolymer and a styrene-butadiene block copolymer are preferable.

Examples of the styrene-butadiene block copolymer include a styrene-butadiene copolymer (SB) and a styrene-butadiene-styrene block copolymer (SBS). Further, it may be a copolymer of tetrapod or more. Among these, SBS is preferable because of the reinforcing effect of the styrene resin and the like.

The content of the styrene-derived structural unit in the styrene-butadiene block copolymer is preferably 20 to 60% by mass, based on 100% by mass of the total of the styrene-derived structural unit and the butadiene-derived structural unit. It is preferably 30 to 50% by mass.

Examples of the hydrogenated additive of the styrene-butadiene block copolymer include a polymer obtained by partially or completely hydrogenating the butadiene portion of the styrene-butadiene block copolymer, and specifically, styrene-butadiene block copolymer. Ethylene-butylene block copolymer (SEB), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-butylene-styrene block copolymer (SBBS), modified styrene-butadiene with functional groups Examples include hydrogenated block copolymers. Examples of the functional group include a hydroxyl group, an acid anhydride group, a carboxy group, a carboxylic acid ester group, an amide group, a sulfonic acid group, a phosphoric acid group, a phosphoric acid ester group, an amino group, an imino group and an epoxy group. ..
Among these, SEBS is preferable from the viewpoint of easy availability, compatibility with propylene resin, and the like.

The content of the styrene-derived structural unit in the styrene-butadiene block copolymer before hydrogenation in the hydrogenated product is preferably 100% by mass based on the total of the styrene-derived structural unit and the butadiene-derived structural unit. Is 10 to 80% by mass, more preferably 20 to 70% by mass.
As the hydrogenated product of the styrene-butadiene block copolymer, it is preferable that 50% or more of the double bonds of the butadiene block portion are hydrogenated, and more preferably 90% or more is hydrogenated.
When the hydrogenation rate is within the above range, compatibility with the propylene-based resin is excellent, which is preferable.

The MFR of the styrene-based block copolymer measured at 200 ° C. and a load of 5 kgf based on ISO 1133 is preferably 0 from the viewpoint that a composition having excellent processability and moldability can be easily obtained. .1 to 100 g / 10 minutes, more preferably 10 to 70 g / 10 minutes.

The content of the styrene-based block copolymer in the present composition is preferably 2 to 15 parts by mass, more preferably 2 to 15 parts by mass, based on 100 parts by mass of the total of the propylene-based resin and the styrene-based resin in the composition. It is 5 to 12 parts by mass.
When the content of the styrene-based block copolymer is within the above range, the above-mentioned effects are exhibited while maintaining or improving the physical properties of the propylene-based resin, and in particular, low molding shrinkage and impact resistance are extremely high levels. A composition satisfying with the above can be easily obtained.

<Styrene resin>
The styrene resin is not particularly limited as long as it is a resin other than the styrene block copolymer, but is preferably a general-purpose polystyrene resin (hereinafter, also referred to as “GPPS”) or an impact-resistant polystyrene resin (hereinafter, “HIPS”). It is also called.). Among these, HIPS is preferable from the viewpoint that a composition having more excellent impact resistance can be easily obtained.
The styrene resin may be used alone or in combination of two or more. Further, the styrene resin may be obtained by synthesizing it by a conventionally known method, or a commercially available product may be used.

The MFR of the styrene resin measured at 200 ° C. and a load of 5 kgf based on ISO 1133 is preferably 2 to 30 g / g from the viewpoint that a composition having excellent processability and moldability can be easily obtained. 10 minutes, more preferably 2 to 20 g / 10 minutes.

The Izod impact strength (23 ° C.) of the styrene resin measured based on ASTM D256 is preferably 5 kJ / m ² or more, from the viewpoint that a molded product having excellent impact resistance can be easily obtained. It is preferably 10 kJ / m ² or more.

The flexural modulus of the styrene resin measured based on ASTM D790 is preferably 2000 MPa or more from the viewpoint that a molded product having excellent mechanical strength can be easily obtained.

The content of the styrene-based resin in the present composition is preferably 35 to 65% by mass, more preferably 40 to 60% by mass, based on 100% by mass of the total of the propylene-based resin and the styrene-based resin in the composition. It is mass%.
When the content of the styrene-based resin is within the above range, the above-mentioned effect is exhibited while maintaining or improving the physical characteristics of the propylene-based resin, and in particular, low molding shrinkage and good appearance are satisfied at an extremely high level. The composition can be easily obtained.

・ GPPS
The GPPS is a styrene-based polymer obtained by radical polymerization by a method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and specifically, (co-polymerization) of one or more kinds of aromatic vinyl monomers. ) Polymers, hydrides of these (co) polymers, and preferably a polymer of one kind of aromatic vinyl monomer. However, it is a polymer other than HIPS.
The GPPS may contain conventionally known additives.

Examples of the aromatic vinyl monomer include α-alkyl substituted styrene such as styrene, α-methylstyrene, α-ethylstyrene, and α-methyl-p-methylstyrene, o-methylstyrene, and m-methylstyrene. Nuclear alkyl-substituted styrenes such as p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, ot-butylstyrene, pt-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, Nuclear halogenated styrene such as p-bromostyrene, dichlorostyrene, dibromostyrene, trichlorostyrene, tribromostyrene, tetrachlorostyrene, tetrabromostyrene, 2-methyl-4-chlorostyrene, p-hydroxystyrene, o-methoxystyrene , Vinyl naphthalene, and among these, styrene and α-methylstyrene are particularly preferable.

・ HIPS
Examples of the HIPS include a rubber-modified styrene-based resin obtained by graft-polymerizing an aromatic vinyl monomer (polymer) on a rubber-like polymer, and examples thereof include a rubber-like polymer and an aromatic vinyl simple substance. The polymer is mixed and polymerized by a known method, for example, a multi-stage polymerization method such as an emulsion polymerization method, a massive polymerization method, a solution polymerization method, a suspension polymerization method, or a massive-suspended two-stage polymerization method. Can be obtained by

Examples of the aromatic vinyl monomer include monomers similar to the aromatic vinyl monomer listed in the GPPS column. Among these, styrene and α-methylstyrene are particularly preferable. These aromatic vinyl monomers may be used alone or in combination of two or more.

Examples of the rubber-like polymer include polybutadienes such as cis type, trans type and low vinyl type obtained by emulsion polymerization or solution polymerization, and random type and block type butadienes obtained by emulsion polymerization or solution polymerization. Examples thereof include styrene copolymer rubber, natural rubber, polyisobutylene rubber, styrene-isoprene copolymer rubber, butyl rubber, ethylene-propylene copolymer rubber, and graft copolymer rubber of these rubbers and styrene. Among these, polybutadiene and butadiene-styrene copolymer rubber are preferable. These rubber-like polymers may be used alone or in combination of two or more.

The HIPS is preferably a resin obtained by polymerizing a mixture containing 70 to 98% by mass of the aromatic vinyl monomer and 2 to 30% by mass of the rubbery polymer, and the rubbery polymer is combined with the single. It is more preferable to contain a graft polymer obtained by graft-polymerizing a part of the monomer. If the amount of the rubber-like polymer is less than 2% by mass, sufficient impact resistance may not be obtained, and if it exceeds 30% by mass, the rigidity may decrease.

<Additives>
The present composition may contain conventionally known additives other than the propylene-based resin, the styrene-based block copolymer, and the styrene-based resin, depending on the desired use, as long as the effects of the present invention are not impaired. ..
Each of the additives may be used alone or in combination of two or more.

Examples of the additive include fillers (eg, pigments, dyes), other polymers, light stabilizers, UV absorbers, antibacterial agents, plasticizers, nucleating agents, heavy metal deactivators, and stabilization aids. Agents, antioxidants, conductive agents, flame retardants, heat stabilizers, antioxidants, lubricants, crosslinkable polymers and fiber reinforced agents.
When the additive is blended in the present composition, a pre-hydrophobicized additive may be used.

-Filler The filler is not particularly limited, and various known fillers such as inorganic fillers and organic fillers that have been used in resin compositions can be used.
Examples of the filler include talc, mica, clay, calcium carbonate, barium sulfate, silica, hydrotalcite, zeolite, aluminum silicate, magnesium silicate, glass fiber, and carbon fiber. Among these, talc and calcium carbonate are preferable, and calcium carbonate is more preferable, in particular, from the viewpoint that a composition satisfying the flexural modulus and chemical resistance at extremely high levels can be easily obtained.

When the present composition contains the filler, the content thereof is preferably 2 to 40 parts by mass, more preferably 5 parts by mass, based on 100 parts by mass of the total of the propylene-based resin and the styrene-based resin in the present composition. ~ 20 parts by mass.
When the purpose is to obtain a composition having a small specific gravity, it is preferable that the filler is not contained.

-Other Polymers This composition contains polyethylene, an ethylene-propylene copolymer (a copolymer using propylene as a comonomer), an ethylene-butene copolymer, and an ethylene-pentene, as long as the effects of the present invention are not impaired. Others such as α-olefin copolymers such as polymers, ethylene-hexene copolymers, ethylene-octene copolymers, butene-hexene copolymers, butene-octene copolymers, hexene-octene copolymers, etc. It may contain a copolymer.
When the present composition contains the other polymer, the content thereof is preferably 30 parts by mass or less with respect to 100 parts by mass of the propylene-based resin.

-Flame retardant Depending on the use of this composition, flame retardant may be required. In this case, it is preferable to add a flame retardant. Depending on the use of this composition, the flame retardancy of UL94 standard is preferably V-2 or higher.
The type and amount of the flame retardant may be appropriately determined in consideration of the flame retardancy required for the present composition.

-Antibacterial agent Depending on the use of this composition, an antibacterial effect may be required. In this case, it is preferable to add an antibacterial substance.
The antibacterial agent is not particularly limited, and examples thereof include an antibacterial agent. As the antibacterial agent, a conventionally known antibacterial agent can be used, but a silver-based antibacterial agent is preferably used.

<Resin composition>
The present composition can be obtained by mixing the respective components, and the respective components can be obtained by a conventionally known device, specifically, a single-screw extruder, a twin-screw extruder, a kneader, a mixer, and a two-roll mill. It is preferable to obtain the mixture by kneading the mixture sufficiently so as to be uniform.

The composition preferably has a sea-island structure containing the sea portion containing the propylene-based resin and the island portion containing the styrene-based resin, and the sea portion containing the propylene-based resin, the styrene-based resin, and the styrene-based. It is more preferable to have a sea-island structure containing an island portion containing a block copolymer, and a structure containing the styrene-based resin in the sea portion containing the propylene-based resin and the styrene-based block copolymer (the styrene-based structure). It is particularly preferable to have a sea-island structure containing an island portion (a structure in which the resin is covered with the styrene-based block copolymer).
When the present composition has such a sea-island structure, it is possible to easily obtain a composition (molded article) having an excellent balance of low molding shrinkage, chemical resistance and impact resistance, and excellent appearance.
The sea-island structure can be evaluated by forming a molded body from the present composition, cutting the molded body, and observing the fracture surface with a scanning electron microscope.
Such a sea-island structure can be formed by using the styrene-based block copolymer, the styrene-based resin, and a predetermined amount of the propylene-based resin.
The sea-island structure is formed by forming a molded product from the present composition, immersing the molded product in tetrahydrofuran (THF) to dissolve polystyrene and styrene-based block copolymers, and then observing the molded product with a scanning electron microscope. , It is possible to judge the presence or absence of sea island structure. Specifically, the sea-island structure can be observed by the method described in the following Examples.

The MFR of this composition measured at 200 ° C. and a load of 5 kgf based on ISO 1133 is preferably 5 g / 10 from the viewpoint that a composition having excellent moldability, particularly injection moldability, can be easily obtained. Minutes or more, more preferably 10 g / 10 minutes or more, preferably 100 g / 10 minutes or less, more preferably 60 g / 10 minutes or less.

The composition preferably satisfies the following requirement (1).
Requirement (1): The molding shrinkage in the direction parallel to the flow direction (MD direction) of the present composition measured according to the JIS K 7152-4 standard is 1.0% or less.

The molding shrinkage in the MD direction is preferably 0.9% or less.
The smaller the molding shrinkage ratio in the MD direction, the smaller the better. Therefore, the lower limit thereof is not particularly limited, but is usually 0.3% or more.
According to the present invention, it is possible to obtain such a composition (molded article) having a low molding shrinkage while containing a large amount of propylene resin, specifically, a composition containing the propylene resin in the above amount. ..
Specifically, the molding shrinkage rate is a value measured by the method described in the following Examples.

The composition preferably satisfies the following requirement (2).
Requirement (2): A molding test piece (width 12 mm, length 80 mm, thickness 3 mm) of the present composition is attached to a plurality of jigs capable of giving different bending strains (%), and the fixed test piece is attached. As a chemical solution, the minimum bending strain value at which cracks occurred when a mixture of glyceryl caprylate, glyceryl caprate, and glyceryl oleate was left in contact with each other in a constant temperature bath at 23 ± 2 ° C for 48 hours. A certain critical strain (%) is 0.9% or more.
The critical strain is preferably 1.05% or more, more preferably 1.35% or more.
Specifically, the critical strain can be measured by the method described in the following Examples.

The Izod impact strength (23 ° C.) of the present composition measured based on ASTM D256 is preferably ² kJ / m 2 or more, more preferably 4 kJ / m ² or more.

The flexural modulus of the present composition measured based on ASTM D790 is preferably 1000 MPa or more from the viewpoint that a composition having excellent mechanical strength can be easily obtained.

The present composition is usually formed into a desired shape by a conventionally known method, specifically, a known method such as injection molding, extrusion molding, blow molding, calendar method, vacuum molding, compression molding and gas assist molding. It is used as a molded product.
Such a molded product may be used as a molded product composed of only the present composition, or may be used by laminating a molded product obtained from the present composition and other members.

The use of this composition is not particularly limited, and examples thereof include uses used in various fields such as household goods, food, agriculture, fisheries, medical care, industry, and construction, and in particular, toilet bowls and toilet seats. , Tanks, washers (washing nozzles), main body operation switches such as washing switches, toilet paper holders, toilet parts such as floors and walls; bathroom parts such as floors, walls, bathtubs, showers and faucets; sinks, washbasins and faucets , Kitchen / washroom parts such as soap boxes; Containers used for storing and transporting food; Kitchen parts such as tableware, cutting boards, balls, triangular corners; Refrigerators, washing machines, vacuum cleaners, fans, dryers , Air conditioners, telephones, electric pots, rice cookers, dishwashers, dish dryers, microwave ovens, mixers, VTRs, TVs, watches, stereos, tape recorders, OA equipment, and other household appliances; Stationery materials; various medical equipment, various containers, sports equipment, daily necessities, building materials, optical equipment, etc.
Among these, it is suitably used for sanitary members related to water surroundings such as bathrooms, toilets, kitchens and washrooms where chemical resistance is particularly required.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The materials used in the following examples and comparative examples are as follows.

<Propene resin>
-"PL400A": SunAllomer PL400A, manufactured by SunAllomer Ltd., homopolypropylene, MFR: 2.7 g / 10 minutes (230 ° C, load 2.16 kgf), 4 g / 10 minutes (200 ° C, load 5 kgf)
-"PM600A": SunAllomer PM600A, manufactured by SunAllomer Ltd., homopolypropylene, MFR: 7.5 g / 10 minutes (230 ° C, load 2.16 kgf), 15 g / 10 minutes (200 ° C, load 5 kgf)
"PM801A": SunAllomer PM801A, manufactured by SunAllomer Ltd., homopolypropylene, MFR: 13 g / 10 minutes (230 ° C, load 2.16 kgf), 29 g / 10 minutes (200 ° C, load 5 kgf)
"PM802A": SunAllomer PM802A, manufactured by SunAllomer Ltd., homopolypropylene, MFR: 20 g / 10 minutes (230 ° C, load 2.16 kgf), 43 g / 10 minutes (200 ° C, load 5 kgf)
-"PM900A": SunAllomer PM900A, manufactured by SunAllomer Ltd., homopropene, MFR: 30 g / 10 minutes (230 ° C, load 2.16 kgf), 58 g / 10 minutes (200 ° C, load 5 kgf)
-"BC03B": Novatec PP BC03B, manufactured by Japan Polypropylene Corporation, block polypropylene, MFR: 30 g / 10 minutes (230 ° C, load 2.16 kgf), 58 g / 10 minutes (200 ° C, load 5 kgf)

<Styrene resin>
-"HIPS": Impact-resistant polystyrene, PSJ H8762, manufactured by PS Japan Corporation, MFR: 4 g / 10 minutes

<Styrene block copolymer>
-"SEBS": hydrogenated styrene-butadiene block copolymer, Tough Tech P2000, manufactured by Asahi Kasei Corporation, MFR: 45 g / 10 minutes- "SBS": styrene-butadiene block copolymer, Toughpren 126S, Asahi Kasei Corporation Made, MFR: 20g / 10 minutes

The MFR of the propylene resin was measured based on ISO 1133, and the MFR of the styrene resin and the styrene block copolymer was measured based on ISO 1133 (200 ° C., load 5 kgf). The value.

[Examples 1 to 11 and Comparative Examples 1 to 5]
A twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., rotation speed: 200 to 600 rpm, screw diameter: 26 mm, L / D: 48) was used so that each component shown in Table 1 had a mass part shown in Table 1. The resin composition was melt-kneaded at 170 to 230 ° C., extruded, and then cut to a predetermined length to obtain a pellet-shaped resin composition.

<MFR>
The MFR (g / 10 min) of the obtained resin composition was measured based on ISO 1133 under the conditions of 200 ° C. and a load of 5 kgf. The results are shown in Table 1.

<Creation of test piece>
Using the obtained resin composition, injection molding was performed under the conditions of an in-mold pressure of 40 MPa, a molding temperature of 200 to 210 ° C., a mold temperature of 40 ° C., an injection speed of 20 to 40 mm / sec, and an injection pressure of 50 to 70 MPa. Was produced.
The test piece for measuring the molding shrinkage rate was molded using a mold having a size of 100 mm square and a thickness of 3 mm. As the test piece for measuring chemical resistance, an injected composition cut into a width of 12 mm in a direction perpendicular to the flow direction (TD direction) (length 80 mm, thickness 3 mm) was used.

<Flexural modulus>
Using the obtained test piece, the flexural modulus (MPa) of the test piece was measured based on ASTM D790. The results are shown in Table 1.

<Izod impact strength>
Using the obtained test piece, the Izod impact strength (kJ / m ² ) of the test piece was measured based on ASTM D256. The results are shown in Table 1.

<Molding shrinkage rate>
Using the obtained test piece, the molding shrinkage rate (%) of the test piece was calculated by the following formula based on JIS K 7152-4.
Molding shrinkage rate (%) = {(length before shrinkage)-(length after shrinkage)} x 100 / (length before shrinkage)

The length before shrinkage is the size of the mold, and the length after shrinkage is the dimension of the molded body after storage at 23 ± 2 ° C. for 48 hours with an image measuring machine manufactured by Nikon Corporation (model number:: It is a value measured using VMR-6555).
The molding shrinkage was measured in a direction parallel to the flow direction of the test piece (MD direction) and in a direction perpendicular to the flow direction (TD direction). The results are shown in Table 1.

<Chemical resistance>
The obtained test piece was attached to a plurality of jigs (jigs as shown in FIG. 1) capable of giving different bending strains (%), and on the test piece fixed in this way, as a chemical solution (caprylic acid). Acid / caprylic acid / oleic acid) When a mixed solution containing 90% or more of glyceryl is in contact with the jig and left in a constant temperature bath at 23 ± 2 ° C. for 48 hours, the minimum bending strain value at which cracks occur is critical. Chemical resistance was evaluated as strain (%). As a jig for applying bending strain (%), bending strain is 0.2%, 0.45%, 0.75%, 0.9%, 1.05%, 1.35%, 1. Jigs with 6% and 2.0% were used. For example, when the bending strain is 0.75%, no crack is generated, and when the bending strain is 0.9%, the critical strain is 0.9% and the bending strain is 0.2. When cracks occurred even in the case of%, the critical strain was set to <0.2%, and when cracks did not occur even when the bending strain was 2.0%, the critical strain was set to> 2.0%. The results are shown in Table 1.
In this evaluation, when the critical strain is 0.9% or more, it can be said that the chemical resistance is excellent.

<Scanning electron microscope observation>
The obtained test piece was cut in a direction parallel to the MD direction, and the cut test piece was immersed in an ultrasonic vibrator filled with tetrahydrofuran (THF) at room temperature for 30 minutes. Then, the test piece was taken out from THF, dried in a vacuum dryer at room temperature for 1 hour, and the cross-sectional structure was observed using a scanning electron microscope (manufactured by Hitachi, Ltd., model number: TM3030 Plus Miniscope) (magnification). : 2000 times). FIG. 2 shows a scanning electron micrograph of the test piece obtained in Example 4, and FIG. 3 shows a scanning electron micrograph of the test piece obtained in Comparative Example 1. The results are shown in Table 1 with the case of having the same sea-island structure as in FIG. 2 as "yes" and the case of not having the sea-island structure as in FIG. 3 as "no".

The circular portion in FIG. 2 contains the styrene resin (HIPS) and the block copolymer (SEBS), and the non-circular portion in FIG. 2 is the propylene resin. That is, it can be said that the test piece obtained in Example 4 has a sea-island structure including a sea portion containing a propylene-based resin and an island portion containing a styrene-based resin and a styrene-based block copolymer. Examples other than this Example 4 also had a similar sea-island structure.
On the other hand, as shown in FIG. 3, the test piece obtained in Comparative Example 1 did not have a sea-island structure. Similarly, other comparative examples other than this comparative example 1 did not have a sea-island structure.

Claims (5)

It contains a styrene-based block copolymer, a styrene-based resin other than the styrene-based block copolymer, and a propylene-based resin having a melt flow rate (230 ° C., load 2.16 kgf) of 3 g / 10 minutes or more.
The propylene-based resin is contained in an amount of 35 to 65% by mass based on 100% by mass of the total of the styrene-based resin and the propylene-based resin.
Resin composition. The resin composition according to claim 1, wherein the ratio of the melt flow rate of the propylene resin (200 ° C., load 5 kgf) to the melt flow rate of the styrene resin (200 ° C., load 5 kgf) is 2 or more. The resin composition according to claim 1 or 2, wherein the melt flow rate (200 ° C., load 5 kgf) is 5 g / 10 minutes or more. The resin composition has a sea-island structure and has a sea-island structure.
The sea part contains the propylene resin,
Shimabe contains the styrene resin,
The resin composition according to any one of claims 1 to 3. A molded product of the resin composition according to any one of claims 1 to 4.

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