JP2022138218A - Core-shell type graft copolymer particle, method for producing the same, and resin composition - Google Patents

Abstract

To provide an acrylic rubber-containing graft copolymer particle which can improve its impact resistance by being blended with a thermoplastic resin.SOLUTION: A core-shell type graft copolymer particle contains a core particle and a shell layer coating the core particle. The core particle contain an agglomerated and grown particle of a rubber particle, and a rubber outer layer coating the agglomerated and grown particle. The rubber particle is composed so that a crosslinking degree on the surface of the particle is higher than a crosslinking degree in the particle. The agglomerated and grown particle is obtained by agglomerating and growing the rubber particle by an acid group-containing polymer. Each of the rubber particle and the rubber outer layer is formed of acrylic rubber obtained by polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer. The shell layer is formed of a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to core-shell type graft copolymer particles, a method for producing the same, and a resin composition containing the particles.

ABS resin (acrylonitrile-butadiene-styrene) has excellent rigidity, impact resistance, heat deformation resistance, etc., so it is used for various miscellaneous goods, interior and exterior materials for automobiles, housings for household appliances such as jar rice cookers, microwave ovens, and vacuum cleaners. It is widely used for parts, housings and parts of OA equipment such as telephones and facsimiles, but it has the disadvantage of low weather resistance.

In order to improve the weather resistance of ABS resin, ASA resin (acrylonitrile-styrene- acrylic) have been developed. However, ASA resin has a problem that it is difficult to develop impact resistance as compared with ABS resin.

In Patent Document 1, a graft copolymer obtained by graft-polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, or an unsaturated acid ester monomer in the presence of crosslinked acrylate-based rubber particles. is blended into an acrylonitrile-styrene resin.

Patent Document 2 describes an acrylic graft copolymer obtained by polymerizing an acrylic rubbery polymer with a monomer selected from the group consisting of a vinyl cyanide compound, an aromatic vinyl compound, and a (meth)acrylic acid alkyl ester. It is described that a polymer (A) and a diene-based graft copolymer (B) obtained by polymerizing a diene-based rubbery polymer with the above-mentioned monomer are blended with an acrylonitrile-styrene-based resin. This document describes that the diene-based rubbery polymer may be coagulated and enlarged using an acid group-containing latex.

JP-A-58-222139 JP 2013-221116 A

Blending a graft copolymer containing an acrylic rubber into a thermoplastic resin such as an acrylonitrile-styrene resin can improve the impact resistance of the resin, but further improvement is desired.

In view of the above-mentioned current situation, the present invention provides acrylic rubber-containing graft copolymer particles capable of improving the impact resistance of a thermoplastic resin by blending them, a method for producing the same, and a resin containing the particles. The object is to provide a composition.

The present inventors have found that the above problems can be solved by adopting a specific configuration in the acrylic rubber contained in the acrylic rubber-containing graft copolymer particles, and have completed the present invention.

That is, the present invention provides a core-shell type graft copolymer particle comprising a core particle and a shell layer covering the core particle, wherein the core particle comprises an aggregated enlarged rubber particle and a wherein the rubber particles are configured such that the degree of cross-linking on the surface of the particles is higher than the degree of cross-linking on the inside of the particles; It is aggregated and enlarged by a polymer, and the rubber particles and the rubber outer layer are each formed of an acrylic rubber obtained by polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer, The shell layer relates to core-shell type graft copolymer particles formed from a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units.
Preferably, the rubber particles are configured such that the degree of cross-linking increases from the center to the surface of the particles.
Preferably, the rubber particle includes a rubber particle core layer located at the center of the particle and a rubber particle surface layer located on the surface of the particle, and the rubber particle surface layer is more crosslinked than the rubber particle core layer. High degree. More preferably, the rubber particles further include a rubber particle intermediate layer located between the rubber particle central layer and the rubber particle surface layer.
Preferably, the acid group-containing polymer is a polymer containing a carboxyl group-containing vinyl monomer unit.
Preferably, the proportion of the core particles in the core-shell type graft copolymer particles is 66 to 90% by weight.
Preferably, the volume average particle diameter of the core particles is 400 to 1200 nm.
The present invention also provides a method for producing core-shell type graft copolymer particles comprising a core particle and a shell layer covering the core particle, comprising a monomer component containing an acrylic monomer and a crosslinkable monomer to form rubber particles configured such that the degree of cross-linking on the surface of the particles is higher than the degree of cross-linking on the inside of the particles; A step of obtaining aggregated enlarged particles of particles, polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer in the presence of the aggregated enlarged particles to form a rubber outer layer covering the aggregated enlarged particles. forming and obtaining a core particle comprising the aggregated enlarged particles and the rubber outer layer, copolymerizing a monomer component comprising an aromatic vinyl compound and a vinyl cyanide compound in the presence of the core particle to obtain the core The present invention also relates to a method for producing core-shell type graft copolymer particles, including the step of forming a shell layer covering particles to obtain the core-shell type graft copolymer particles.
Preferably, in the step of forming the rubber particles, the ratio of the crosslinkable monomer to the monomer component is increased over time, so that the degree of crosslinking increases from the center to the surface of the rubber particles. form rubber particles that are
Preferably, in the step of forming the rubber particles, a monomer component containing an acrylic monomer and a crosslinkable monomer are polymerized in a multistage manner so that the central layer of the rubber particles and the degree of crosslinking from the central layer of the rubber particles form a rubber particle containing a rubber particle surface layer with a high
Preferably, the acid group-containing polymer is a polymer containing a carboxyl group-containing vinyl monomer unit.
Furthermore, the present invention provides a resin comprising 100 parts by weight of a thermoplastic resin that is a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit, and 10 to 100 parts by weight of the core-shell type graft copolymer particles. It also relates to a composition or a molded article obtained by molding the resin composition.

According to the present invention, acrylic rubber-containing graft copolymer particles capable of improving impact resistance by blending with thermoplastic resin, a method for producing the same, and a resin composition containing the particles are provided. can provide.

Process diagram for explaining the process of producing core-shell type graft copolymer particles according to a preferred embodiment

Embodiments of the present invention are described in detail below.
<Core-shell type graft copolymer particles>
A core-shell type graft copolymer particle according to the present disclosure has a core-shell structure including a core particle and a shell layer covering the core particle. A core particle refers to a particle located inside a core-shell type graft copolymer particle. On the other hand, the shell layer is located on the surface side of the core-shell type graft copolymer particles, refers to a polymer layer covering the surface of the core particles, and is also called a graft layer. The shell layer covers the surface of the core particles, but is not limited to covering the entire surface of the core particles, and may cover at least part of the surface of the core particles.
In FIG. 1, the core-shell type graft copolymer particles are indicated by reference numeral 24, the core particles are indicated by reference numeral 23, and the shell layer is indicated by reference numeral 15.

<Core particle>
The core particles include aggregated enlarged particles of rubber particles and an outer rubber layer covering the aggregated enlarged particles. Here, rubber means a polymer having a crosslinked structure (hereinafter also referred to as a crosslinked polymer). Since the core particles are formed from a crosslinked polymer, impact resistance can be imparted to the matrix resin by incorporating the core-shell type graft copolymer particles into the matrix resin.
In FIG. 1 , rubber particles are indicated by reference numeral 21 , aggregated and enlarged rubber particles are indicated by reference numeral 22 , rubber outer layers are indicated by reference numeral 14 , and core particles are indicated by reference numeral 23 .

The crosslinked polymer forming each of the rubber particles and the rubber outer layer is an acrylic rubber obtained by polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer. The crosslinked polymer forming the rubber particles and the crosslinked polymer forming the rubber outer layer may be the same or different. Moreover, it is preferable that the core particles are composed only of acrylic rubber and do not contain siloxane rubber and butadiene rubber.

The acrylic monomer is not particularly limited, but examples include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, behenyl acrylate, and the like. acrylic acid alkyl esters; aromatic ring-containing acrylates such as phenoxyethyl acrylate and benzyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; glycidyl acrylates such as glycidyl acrylate and glycidyl alkyl acrylate; acrylates and the like. As acrylic monomers, only one type may be used, or two or more types may be used in combination.

As the acrylic monomer, acrylic acid alkyl ester is preferable. The number of carbon atoms in the alkyl group of the acrylic acid alkyl ester is preferably 1 to 22 carbon atoms, more preferably 1 to 18 carbon atoms, still more preferably 2 to 12 carbon atoms, and even more preferably 2 to 6 carbon atoms. Butyl acrylate is particularly preferable as the acrylic monomer.

The monomer component forming the acrylic rubber may consist only of the acrylic monomer, but it may contain one unsaturated bond copolymerizable with the acrylic monomer in one molecule. It may also contain other unique monomers. The other monomers are not particularly limited, but include, for example, methacrylic monomers, aromatic vinyl compounds, vinyl cyanide compounds, halogenated vinyl compounds such as vinyl chloride and chloroprene, vinyl acetate, ethylene and propylene. Examples include alkenes.

In the monomer component (excluding the crosslinkable monomer) forming the acrylic rubber, the content of the acrylic monomer is preferably 50 to 100% by weight, more preferably 70 to 100% by weight. Preferably, 80 to 100% by weight is more preferable, 90 to 100% by weight is even more preferable, and 95 to 100% by weight is particularly preferable.

The crosslinkable monomer used for forming the acrylic rubber is a compound having two or more unsaturated bonds in one molecule that are copolymerizable with the acrylic monomer. Although not particularly limited, specific examples include (meth)acrylates having an allyl group such as allyl (meth)acrylate, allylalkyl (meth)acrylate, and allyloxyalkyl (meth)acrylate; ) acrylate, butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, poly (meth) having two or more acrylic groups Functional (meth)acrylates; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene and the like. Among them, allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene are preferred, and allyl methacrylate is particularly preferred. As the crosslinkable monomer, only one type may be used, or two or more types may be used in combination. (Meth)acrylic is a collective notation of acrylic and methacrylic.

The ratio of the core particles to the core-shell type graft copolymer particles is preferably 60% by weight or more, more preferably 65% by weight or more. In particular, 66% by weight or more is preferable, 68% by weight or more is more preferable, and 69% by weight or more is even more preferable because excellent impact resistance can be exhibited. The upper limit of the ratio is preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, even more preferably 78% by weight or less, and particularly preferably 76% by weight or less.

From the viewpoint of impact resistance, the volume average particle diameter of the core particles is preferably 200 nm or more, more preferably 300 nm or more. In particular, the thickness is preferably 400 nm or more, more preferably 500 nm or more, even more preferably 600 nm or more, and particularly preferably 700 nm or more, because excellent impact resistance can be exhibited. Although the upper limit of the volume average particle diameter is not particularly limited, from the viewpoint of productivity, it is preferably 1200 nm or less, more preferably 1000 nm or less, even more preferably 900 nm or less, and particularly preferably 800 nm or less. The volume average particle size of the core particles is a value measured by using a particle size measuring device in the state of a latex of polymer particles, as shown in the Examples section. The particle size of the core particles can be controlled by the types and amounts of the acid group-containing polymer, initiator, reducing agent, emulsifier, etc., polymerization temperature, polymerization time, and the like.

<Rubber particles>
The rubber particles are configured such that the degree of cross-linking on the surface of the particles is higher than the degree of cross-linking on the inside of the particles. By adopting such a specific configuration for the degree of cross-linking of the rubber particles, it is possible to dramatically improve the impact resistance of the thermoplastic resin by blending the core-shell type graft copolymer particles. The degree of cross-linking refers to the density of the cross-linked structure introduced into the polymer by the cross-linking monomer. The degree of cross-linking can be controlled by adjusting the ratio of the amount of cross-linkable monomer to the amount of monomer component, and the higher the ratio of the amount of cross-linkable monomer, the higher the degree of cross-linking.

According to one aspect of the present embodiment, the rubber particles are configured such that the degree of cross-linking increases from the center to the surface of the particles. The degree of cross-linking may be configured to increase continuously or may be configured to increase discontinuously. Such rubber particles are formed by adding a monomer component and a crosslinkable monomer so that the ratio of the amount of the crosslinkable monomer to the amount of the monomer component increases with time when forming the rubber particles. It can be realized by controlling.

In this aspect, the amount of the crosslinkable monomer used is preferably adjusted within the range of 0.001 to 10 parts by weight with respect to 100 parts by weight of the monomer component constituting the rubber particles. The range is more preferably 0.01 to 5 parts by weight, still more preferably 0.05 to 3 parts by weight, and particularly preferably 0.1 to 1 part by weight.

According to another aspect of this embodiment, the rubber particles have a multi-layered structure consisting of at least two layers. In this multilayer structure, the degree of cross-linking in each layer is adjusted so that the degree of cross-linking on the surface of the rubber particle is higher than the degree of cross-linking on the inside of the rubber particle.
Specifically, the rubber particles include at least a rubber particle center layer located in the center of the particle and a rubber particle surface layer located on the surface of the particle, and the rubber particle surface layer is the rubber particle surface layer. It is configured so that the degree of cross-linking is higher than that of the particle center layer.

The rubber particles may have a two-layer structure composed only of a rubber particle center layer and a rubber particle surface layer.
However, the rubber particles may further include at least one rubber particle intermediate layer between the rubber particle central layer and the rubber particle surface layer. In this case, the rubber particle surface layer preferably has a higher degree of cross-linking than the rubber particle intermediate layer, and the rubber particle intermediate layer preferably has a higher degree of cross-linking than the rubber particle central layer.

The upper part of FIG. 1 shows the formation of rubber particles 21 having a three-layer structure. The central layer of rubber particles is indicated by reference numeral 11, the intermediate layer of rubber particles is indicated by reference numeral 12, and the surface layer of rubber particles is indicated by reference numeral 13. However, two or more intermediate layers of rubber particles may exist, that is, the rubber particles may have a structure of four or more layers.

In the core-shell type graft copolymer particles according to the other aspect, the type or amount of the monomer component constituting each layer and the type of crosslinkable monomer used in each layer may be the same or different. may

In the other aspect, the amount of the crosslinkable monomer used in each layer is preferably selected within the range of 0.001 to 10 parts by weight with respect to 100 parts by weight of the monomer component constituting each layer. . The range is more preferably 0.01 to 5 parts by weight, still more preferably 0.05 to 3 parts by weight, and particularly preferably 0.1 to 1 part by weight.

More specifically, the amount of the crosslinkable monomer used in the rubber particle central layer is 0.001 to 3 parts by weight with respect to 100 parts by weight of the monomer component constituting the rubber particle central layer. is preferred, 0.01 to 2 parts by weight is more preferred, 0.05 to 1 part by weight is even more preferred, and 0.1 to 0.3 parts by weight is even more preferred.

The amount of the crosslinkable monomer used in the rubber particle surface layer is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the monomer component constituting the rubber particle surface layer. 1 to 5 parts by weight is more preferred, 0.2 to 3 parts by weight is even more preferred, and 0.3 to 1 part by weight is even more preferred.

The amount of the crosslinkable monomer used in the rubber particle intermediate layer is preferably larger than the amount of the crosslinkable monomer used in the rubber particle central layer and less than the amount of the crosslinkable monomer used in the rubber particle surface layer. .

<Aggregated Enlarged Particles of Rubber Particles>
Aggregated enlarged particles of rubber particles refer to particles in which the rubber particles described above are aggregated and enlarged by an acid group-containing polymer. Although the details will be described later, by adding latex of an acid group-containing polymer to a system containing rubber particles, the rubber particles can be aggregated and enlarged. At this time, a plurality of rubber particles aggregate to increase the particle size several times. In the middle part of FIG. 1, as a conceptual diagram, a plurality of rubber particles 21 are aggregated to form aggregated enlarged particles 22 of rubber particles.

<Acid group-containing polymer>
The acid-group-containing polymer that aggregates and enlarges rubber particles refers to a polymer having a functional group exhibiting acidity. The functional group exhibiting acidity is not particularly limited, but a carboxyl group is preferred. The acid group-containing polymer is particularly preferably a polymer containing a carboxyl group-containing vinyl monomer unit. A coalescence is more preferred. Examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. Among these, acrylic acid and methacrylic acid are preferred. Only one type of acid group-containing polymer may be used, or two or more types may be used in combination.

As the acid group-containing polymer, 5 to 30% by weight of one or more carboxyl group-containing vinyl monomers and an alkyl group having 1 to 12 carbon atoms are used from the viewpoint of easiness of aggregation and enlargement and thermal stability of the resin. and 0 to 60% by weight of another copolymerizable vinyl monomer are preferably polymerized.

As the one or more (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 12 carbon atoms, an ester of acrylic acid and a linear or side chain alcohol having 1 to 12 carbon atoms, and methacryl Examples include esters of acids with linear or branched alcohols having 1 to 12 carbon atoms. From the viewpoint of production stability, the number of carbon atoms in the alkyl group is preferably 1 to 8. Specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and the like. mentioned. These may be used alone or in combination of two or more.

The other copolymerizable vinyl monomer is not particularly limited, but examples include aromatic vinyl compounds such as styrene, α-methylstyrene and p-methylstyrene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; Examples include polyfunctional vinyl monomers having two or more polymerizable vinyl groups in one molecule, such as allyl methacrylate, polyethylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, and triallyl trimellitate. be done. These may be used alone or in combination of two or more.

In particular, from the viewpoint of easiness of aggregation and enlargement and production stability, the acid group-containing polymer according to a preferred embodiment contains one or more carboxyl groups selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. 5 to 25% by weight of a group-containing vinyl monomer, 25 to 95% by weight of one or more (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 12 carbon atoms, an aromatic vinyl compound, and a vinyl cyanide compound and polyfunctional vinyl monomers by polymerizing 0 to 60% by weight of another vinyl monomer.

<Rubber outer layer>
The core-shell graft copolymer particles according to the present disclosure comprise an outer rubber layer covering the agglomerated enlarged particles of rubber particles described above. A core particle is composed of agglomerated enlarged rubber particles and an outer rubber layer. In FIG. 1 , agglomerated enlarged particles of rubber particles are indicated by reference numeral 22 , rubber outer layers are indicated by reference numeral 14 , and core particles are indicated by reference numeral 23 . Although the rubber outer layer covers the surface of the aggregated enlarged particles, it is not limited to covering the entire surface of the aggregated enlarged particles, and may cover at least a part of the surface of the aggregated enlarged particles.
As described above, the outer rubber layer is made of acrylic rubber obtained by polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer.

From the viewpoint of improving impact resistance, the degree of cross-linking of the rubber outer layer is preferably higher than the degree of cross-linking of the surface of the rubber particles (or the degree of cross-linking of the surface layer of the rubber particles). The amount of the crosslinkable monomer used in the outer rubber layer is not particularly limited, but it is preferably 0.1 to 20 parts by weight, preferably 1 to 18 parts by weight, based on 100 parts by weight of the monomer component constituting the outer rubber layer. Parts by weight are more preferred, 3 to 15 parts by weight are more preferred, and 5 to 12 parts by weight are more preferred.

From the viewpoint of impact resistance, the ratio of the rubber outer layer in the core particles is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, even more preferably 3 to 30% by weight, and 4 to 20% by weight. Even more preferred, 5 to 15% by weight is particularly preferred.

(shell layer)
The shell layer is a polymer layer that covers the surface of the core particles and is the outermost layer of the graft copolymer particles. The shell layer is preferably grafted to the core particle, but may include non-grafted layers. The shell layer improves compatibility between the graft copolymer particles and the matrix resin, and enables the graft copolymer particles to be dispersed in the resin composition in the form of primary particles. The shell layer may be composed of a single layer, or may be composed of a plurality of layers having different compositions.

The shell layer is formed of a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units for improving compatibility with the matrix resin. The copolymer may further contain a (meth)acrylate unit.

Examples of the aromatic vinyl compound include, but are not limited to, styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene and dichlorostyrene. Of these, styrene is preferred.

Although the vinyl cyanide compound is not particularly limited, examples thereof include acrylonitrile and methacrylonitrile. Of these, acrylonitrile is preferred.

The (meth)acrylic acid ester is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and (meth)acrylic ester. (meth)acrylic acid alkyl esters such as octyl acid, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, etc. aromatic ring-containing (meth)acrylates; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; glycidyls such as glycidyl (meth)acrylate and glycidylalkyl (meth)acrylate (Meth)acrylates; alkoxyalkyl (meth)acrylates, and the like.

From the viewpoint of compatibility with the matrix resin, the proportion of the aromatic vinyl compound unit in the total copolymer constituting the shell layer is preferably 30 to 95% by weight, more preferably 50 to 90% by weight, and 60 to 85% by weight. % is more preferred, and 70-82% by weight is particularly preferred. Also, the proportion of vinyl cyanide compound units is preferably 5 to 70% by weight, more preferably 10 to 50% by weight, even more preferably 15 to 40% by weight, and particularly preferably 18 to 30% by weight.

The shell layer may be formed from a copolymer having a crosslinked structure, but is preferably formed from a copolymer having no crosslinked structure. That is, the shell layer is preferably formed from a polymer synthesized without using a crosslinkable monomer.

<Method for Producing Core-Shell Graft Copolymer Particles>
The production of the graft copolymer particles is not particularly limited, but for example, emulsion polymerization, miniemulsion polymerization, microemulsion polymerization, or soap-free emulsion polymerization can be used. Among them, emulsion polymerization is preferred.

Emulsifiers that can be used in emulsion polymerization are not particularly limited, and anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants and the like can be used. Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone and polyacrylic acid derivatives may also be used in combination.

The anionic surfactant is not particularly limited, but includes, for example, the following compounds: potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium oleate diethanolamine salt, sodium oleate, palmitic acid. Fatty acid soaps such as potassium, potassium stearate, sodium stearate, mixed fatty acid soda soap, semi-hardened tallow fatty acid soda soap, castor oil potassium soap; sodium dodecyl sulfate, sodium higher alcohol sulfate, triethanolamine dodecyl sulfate, ammonium dodecyl sulfate, poly Alkyl sulfate ester salts such as sodium oxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium 2-ethylhexyl sulfate; sodium alkylbenzene sulfonate such as sodium dodecylbenzene sulfonate; sodium dialkylsulfosuccinate such as sodium di-2-ethylhexylsulfosuccinate; sodium alkylnaphthalenesulfonate; sodium alkyldiphenyletherdisulfonate; potassium alkylphosphate; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; Sodium salt of acid formalin condensate; polycarboxylic acid type polymer anion; sodium acyl (beef tallow) methyl taurate; sodium acyl (coconut) methyl taurate; sodium cocoyl isethionate; α-sulfo fatty acid ester sodium salt; sodium sulfonate; oleyl sarcosine; lauroyl sarcosine sodium; rosinate soap;

The nonionic surfactant is not particularly limited, but includes, for example, the following compounds: polyoxyethylene alkylallyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether; Polyoxyethylene alkyl ethers, polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate polyoxyethylene fatty acid esters such as ate, oxyethylene/oxypropylene block copolymers, and the like.

The cationic surfactant is not particularly limited, but includes, for example, the following compounds: alkylamine salts such as coconutamine acetate, stearylamine acetate, octadecylamine acetate, tetradecylamine acetate; lauryltrimethylammonium chloride; quaternary ammonium salts such as stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride, alkylbenzyldimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride;

The amphoteric surfactant is not particularly limited, but includes, for example, the following compounds: Alkylbetaines such as laurylbetaine, stearylbetaine, dimethyllaurylbetaine; sodium lauryldiaminoethylglycinate; amidobetaine; imidazoline; Ethylimidazolinium betaine, etc.

These emulsifiers may be used alone or in combination of two or more. As the emulsifier, sodium dialkylsulfosuccinate or a surfactant having an oxyethylene structure is preferred, and sodium polyoxyethylene lauryl ether phosphate is particularly preferred. By adjusting the amount of emulsifier used, the average particle size of the polymer particles can be controlled.

When the emulsion polymerization method is employed, known polymerization initiators such as 2,2′-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate and ammonium persulfate can be used as thermal decomposition initiators. can.

In addition, organic peroxides such as t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide and t-hexyl peroxide Oxides; peroxides such as inorganic peroxides such as hydrogen peroxide, potassium persulfate and ammonium persulfate; sodium formaldehyde sulfoxylate; glucose; transition metal salts such as iron (II) sulfate; a chelating agent; and at least one reducing agent selected from the group consisting of pyrophosphates such as sodium pyrophosphate.

When a redox initiator is used, polymerization can be carried out at a low temperature at which the peroxide is not substantially thermally decomposed, and the polymerization temperature can be set within a wide range, which is preferable. Among them, organic peroxides such as cumene hydroperoxide, dicumyl peroxide and t-butyl hydroperoxide are preferably used as redox initiators. The amount of the initiator used, and the amount of the reducing agent, transition metal salt, chelating agent, etc. used when a redox initiator is used may be within a known range. A known chain transfer agent can be used in a known amount when polymerizing the crosslinkable monomer. Surfactants can additionally be used and are within the known range.

As the solvent used for emulsion polymerization, any solvent can be used as long as it allows the emulsion polymerization to proceed stably.

The temperature during emulsion polymerization is not particularly limited as long as the emulsifier is uniformly dissolved in the solvent.

Specifically, the core-shell type graft copolymer particles according to the present disclosure can be produced by sequentially performing the following steps (I) to (IV).
Step (I): First, in the presence of an emulsifier and an initiator, a monomer component containing an acrylic monomer and a crosslinkable monomer are polymerized to increase the crosslinkage of the surface of the particles from the degree of crosslinkage inside the particles. Forming rubber particles that are configured to have a higher degree of hardness.

According to one aspect of the present embodiment, in step (I), polymerization is performed while adding the monomer component and the crosslinkable monomer to the reaction system, and at that time, the crosslinkable monomer for the monomer component The addition amount of the monomer component and the crosslinkable monomer is controlled so that the ratio increases with time. As a result, it is possible to form rubber particles in which the degree of cross-linking increases from the center to the surface of the rubber particles. The ratio of the crosslinkable monomer to the monomer component may be increased continuously or discontinuously. Moreover, it may increase linearly or may increase non-linearly. Incidentally, the monomer component and the crosslinkable monomer may be added separately, or may be mixed and added.

According to another aspect of the present embodiment, in the step (I), by multi-stage polymerization of a monomer component containing an acrylic monomer and a crosslinkable monomer, at least the rubber particles located at the center of the particles A rubber particle is formed that includes a central layer and a rubber particle surface layer located on the surface of the particle. At this time, the ratio of the crosslinkable monomer to the monomer component when forming the rubber particle surface layer is higher than the ratio of the crosslinkable monomer to the monomer component when forming the rubber particle core layer. By setting the ratio, it is possible to form a rubber particle surface layer having a higher degree of cross-linking than the rubber particle center layer.

A rubber particle intermediate layer can also be formed between the rubber particle central layer and the rubber particle surface layer by the multistage polymerization. In this case, the ratio of the crosslinkable monomer to the monomer component when forming the rubber particle intermediate layer is higher than the ratio of the crosslinkable monomer to the monomer component when forming the rubber particle central layer. It is preferable to set the ratio of the crosslinkable monomer to the monomer component when forming the rubber particle surface layer higher than the ratio when forming the rubber particle intermediate layer.

Step (II): Next, an acid group-containing polymer latex is added to the system containing the rubber particles, and the rubber particles are aggregated and enlarged by the acid group-containing polymer latex to obtain aggregated enlarged particles of rubber particles.
The acid group-containing polymer latex can be produced by emulsion polymerization. The details are the same as the emulsion polymerization in the production of the core-shell type graft copolymer particles described above.
Before adding the acid group-containing polymer latex, the system containing rubber particles (for example, latex of rubber particles) is preferably adjusted to pH 10 or less.

The amount of the acid group-containing polymer added is preferably 0.1 to 15 parts by weight, preferably 0.3 to 15 parts by weight, based on 100 parts by weight of the solid content of the rubber particles, from the viewpoint of impact resistance and production stability. 10 parts by weight is more preferred, and 0.5 to 8 parts by weight is even more preferred.
Further, the solid content concentration of the rubber particle latex at the time of aggregation and enlargement is preferably 10 to 50% by weight, more preferably 15 to 45% by weight, from the viewpoint of controlling the aggregation and enlargement characteristics.

In order to sufficiently promote aggregation and enlargement of rubber particles, after adding latex of an acid group-containing polymer to a system containing rubber particles, an alkali such as sodium hydroxide or potassium hydroxide is added. Uniform stirring for about minutes to 3 hours is preferable. By adding an alkali to increase the pH of the system, the particle size of the acid group-containing polymer in the latex increases, and the aggregation and enlargement of the rubber particles tend to progress therein. The temperature of the system during stirring may be room temperature, but is preferably 35 to 85.degree. C., more preferably 40 to 80.degree.

Step (III): Next, a monomer component containing an acrylic monomer, a crosslinkable monomer, and, if necessary, an initiator are added to the system containing the aggregated enlarged particles of the rubber particles, and the aggregated The monomer component and the crosslinkable monomer are polymerized in the presence of the enlarged particles to form a rubber outer layer covering the aggregated enlarged particles to obtain a core particle containing the aggregated enlarged particles and the rubber outer layer.

Step (IV): Next, a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound and, if necessary, an initiator are added to the system containing the core particles, and the The core-shell type graft copolymer particles can be obtained by copolymerizing the monomer components to form a shell layer covering the core particles.

After the core-shell type graft copolymer particles are formed, the latex is coagulated by adding one or more coagulants selected from the group consisting of acids and salts, and heat-treated at a temperature of, for example, 40° C. or higher and 110° C. or lower. Then, the core-shell type graft copolymer particles can be separated by washing, dehydrating, drying, and sieving through a sieve of a predetermined size.

A preferred embodiment of the process for producing core-shell type graft copolymer particles will be described below with reference to FIG. FIG. 1 shows the case where the rubber particles have a three-layer structure.
First, the rubber particle core layer 11 made of acrylic rubber is formed by emulsion polymerization. Next, as a second layer, the rubber particle intermediate layer 12 having a higher degree of cross-linking than the rubber particle central layer 11 is formed. Furthermore, as a third layer, the rubber particle surface layer 13 having a higher cross-linking degree than the rubber particle intermediate layer 12 is formed to form the rubber particles 21 having a three-layer structure.
Next, an acid group-containing polymer latex is added to a system containing rubber particles 21 having a three-layer structure to aggregate and enlarge rubber particles 21 to obtain aggregated enlarged particles 22 of rubber particles.
Further, the rubber outer layer 14 is formed as the fourth layer in a system containing the aggregated enlarged particles 22 of rubber particles to obtain the core particles 23 composed of the aggregated enlarged particles 22 and the rubber outer layer 14 .
By graft-polymerizing the shell layer 15 onto the core particles 23, the core-shell type graft copolymer particles 24 can be obtained.

<Resin composition>
By blending the core-shell type graft copolymer particles according to the present disclosure with a thermoplastic resin to form a resin composition, the impact resistance of the thermoplastic resin can be specifically increased. The core-shell type graft copolymer particles according to the present disclosure are sufficiently separated from each other in the thermoplastic resin, which is the matrix resin, and can exhibit extremely good dispersibility. Furthermore, in the matrix resin, each graft copolymer particle can be greatly deformed and have a flattened shape. Since conventionally known core-shell type particles have a substantially spherical shape in the matrix resin, the core-shell type graft copolymer particles according to the present disclosure are considered to have extremely high flexibility. Combining these physical properties is believed to lead to specific improvement in impact resistance due to the blending of the core-shell type graft copolymer particles according to the present disclosure. However, the core-shell type graft copolymer particles and resin composition according to the present disclosure are not limited to the above description.

The thermoplastic resin is preferably a thermoplastic resin that is a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units.
The aromatic vinyl compound constituting the thermoplastic resin is not particularly limited, but examples include styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene, dichlorostyrene, and the like. is mentioned. These may use only 1 type and may use 2 or more types together. Of these, styrene and α-methylstyrene are preferred, and styrene is particularly preferred.

Although the vinyl cyanide compound constituting the thermoplastic resin is not particularly limited, examples thereof include acrylonitrile and methacrylonitrile. These may use only 1 type and may use 2 types together. Acrylonitrile is preferred.

The thermoplastic resin may be a copolymer composed only of aromatic vinyl compound units and vinyl cyanide compound units. It may be a copolymer further containing.

The other copolymerizable vinyl compound is not particularly limited, but examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and acrylic acid. (Meth)acrylic acid alkyl esters having an alkyl group of 1 to 12 carbon atoms such as 2-ethylhexyl, maleimide compounds such as maleimide, N-phenylmaleimide, cyclohexylmaleimide, acrylic acid, methacrylic acid, isopropenylnaphthalene, acrylamide , methacrylamide, glycidyl acrylate, glycidyl methacrylate, and the like. These may use only 1 type and may use 2 or more types together.

The content of the aromatic vinyl compound in the thermoplastic resin is not particularly limited, but is preferably 60 to 85% by weight, more preferably 65 to 80% by weight. Although the content of the vinyl cyanide compound is not particularly limited, it is preferably 15 to 40% by weight, more preferably 20 to 35% by weight. The content of the other copolymerizable vinyl compound is also not particularly limited, but is preferably 0 to 25% by weight, more preferably 0 to 15% by weight.

Specific examples of the thermoplastic resin include styrene-acrylonitrile copolymer, α-methylstyrene-acrylonitrile copolymer, styrene-α-methylstyrene-acrylonitrile copolymer, styrene-maleimide-acrylonitrile copolymer, styrene- α-methylstyrene-maleimide-acrylonitrile copolymer, styrene-acrylonitrile-methyl methacrylate copolymer, α-methylstyrene-acrylonitrile-methyl methacrylate copolymer, styrene-α-methylstyrene-acrylonitrile-methyl methacrylate copolymer, Styrene-maleimide-acrylonitrile-methyl methacrylate copolymer, styrene-α-methylstyrene-maleimide-acrylonitrile-methyl methacrylate copolymer, and the like. These may use only 1 type and may use 2 or more types together.

The content of the core-shell type graft copolymer particles in the resin composition is preferably 10 to 100 parts by weight with respect to 100 parts by weight of the thermoplastic resin, from the viewpoint of improving impact resistance. 80 parts by weight is more preferred, 20 to 60 parts by weight is more preferred, and 25 to 50 parts by weight is particularly preferred.

The resin composition may further contain a thermoplastic resin other than the thermoplastic resins described above. Although such thermoplastic resins are not particularly limited, examples thereof include acrylic resins such as polymethylmethacrylic acid, vinyl chloride resins, polycarbonate resins, amide resins, and polyester resins. These may use only 1 type and may use 2 or more types together.

The resin composition may optionally contain a flame retardant, an antibacterial agent, a release agent, a nucleating agent, a plasticizer, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a compatibilizer, a pigment, and a dye. , an antistatic agent, a lubricant, and the like may be added as appropriate. A blending amount of each additive can be appropriately determined by those skilled in the art. These may use only 1 type and may use 2 or more types together.

In particular, phenol-based, sulfur-based, phosphorus-based, and hindered amine-based antioxidants or stabilizers; benzophenone-based, benzotriazole-based UV absorbers; organopolysiloxanes, aliphatic hydrocarbons, esters of higher fatty acids and higher alcohols, Internal lubricants and external lubricants such as amides or bisamides of higher fatty acids and modified products thereof, oligoamides, and metal salts of higher fatty acids can be preferably added.

The resin composition can be produced, for example, by mixing the core-shell type graft copolymer particles and the thermoplastic resin in the form of latex, slurry, solution, powder, pellets, or a combination thereof. can. When the core-shell type graft copolymer particles and the thermoplastic resin are latex, for example, the latex contains alkaline earth metal salts such as calcium chloride, magnesium chloride and magnesium sulfate, and alkali metal salts such as sodium chloride and sodium sulfate. Alternatively, an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, or acetic acid may be added to coagulate the latex into a slurry, followed by dehydration and drying. A spray drying method can also be used. At this time, some of the additives such as stabilizers may be added in the form of a dispersion to the latex or slurry.

The resin composition is prepared by blending the core-shell type graft copolymer particles and the thermoplastic resin powder, pellets, etc. with optional additives as necessary, followed by Banbury mixer, roll mill, single-screw extruder, or twin-screw extruder. It can be kneaded by a known melt-kneader such as an extruder, and shaped into a target molded body by a known molding method such as injection molding, extrusion molding, blow molding, and the like.

The resin composition can be used in various applications such as electrical/electronic applications, construction applications, and vehicle applications. Specifically, personal computers, liquid crystal displays, projectors, PDAs, printers, copiers, fax machines, video cameras, digital cameras, mobile phones (smartphones), portable audio equipment, game machines, DVD recorders, microwave ovens, rice cookers, etc. Electrical and electronic applications; Architectural applications such as translucent plates for roads, lighting windows, carports, lighting lenses, lighting covers, sizing for building materials, doors; It can be used for vehicle applications such as display, illumination, driver's seat panel, and the like.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Hereinafter, "parts" and "%" indicate "parts by weight" and "% by weight" unless otherwise specified.

(Method for measuring average particle size of polymer particles)
As the average particle size of the polymer particles, the volume average particle size was measured in the state of polymer particle latex. Nanotrac Wave manufactured by Nikkiso Co., Ltd. was used as a measuring device. The calculation mode was set to UPA compatible mode.

(Synthesis example 1)
<Production of acid group-containing polymer latex>
2836 g of deionized water and 180 g of 2% sodium dialkylsulfosuccinate ("Pelex OT-P" manufactured by Kao Corporation) were added to an 8 L polymerization vessel, the temperature was raised to 70° C., and nitrogen was flowed. 59.2 g styrene, 40.8 g butyl acrylate, 0.22 g 52% p-menthane hydroperoxide, 0.0015 g ferrous sulfate (FeSO _{4.7H 2} O), and 0.025 g disodium ethylenediaminetetraacetate was dissolved in 8.0 g of deionized water, 50 g of deionized water was added, and 5% sodium formaldehyde sulfoxylate (hereinafter also referred to as “Rongalite”) was added. Polymerization started.

After 30 minutes, 80 g of 5% Rongalite was added, and a mixture of 236.8 g of styrene, 163.2 g of butyl acrylate, 2.5 g of t-butyl mercaptan, and 0.92 of 52% p-menthane hydroperoxide was added for 70 minutes. was added over a period of time, followed by an additional 50 g of deionized water. After 10 minutes, a mixture of 808 grams of styrene, 392 grams of butyl acrylate, 300 grams of methacrylic acid, and 7.5 grams of t-butyl mercaptan was added over 210 minutes. Rongalite and p-menthane hydroperoxide were appropriately added to obtain an acid group-containing polymer latex having a conversion rate of 99.9%, a solid content concentration of 31.5% and a volume average particle size of 200 nm.

(Example 1)
<Production of graft copolymer latex>
(rubber particles)
3400 g of deionized water, 64.3 g of saponified potassium hydroxide of 15.6% beef tallow fatty acid (LUNAC TH manufactured by Kao Corporation), and 50 g of 2% sodium carbonate are charged into an 8 L polymerization machine, heated to 50° C., Nitrogen was flowed.

A mixture of 100 g of butyl acrylate, 0.125 g of allyl methacrylate, and 0.26 g of 69% t-butyl hydroperoxide was added to the polymerizer, 0.0108 g of ferrous sulfate _{( FeSO4.7H2O} ), and A solution obtained by dissolving 0.018 g of disodium ethylenediaminetetraacetate in 5.7 g of deionized water was added, and 32.0 g of 5% Rongalite was added, followed by stirring for 30 minutes.

The following beakers (i) and (ii) were prepared.
Beaker (i): 0.125% solution of allyl methacrylate with respect to butyl acrylate: mixture of 660 g of butyl acrylate, 0.825 g of allyl methacrylate, and 1.7 g of 69% t-butyl hydroperoxide Beaker (ii) : A solution of 0.5% allyl methacrylate with respect to butyl acrylate: A mixture of 540 g of butyl acrylate, 2.7 g of allyl methacrylate, and 1.4 g of 69% t-butyl hydroperoxide

The solution was added from beaker (ii) to beaker (i) at a rate of 3.0 g/min over 3 hours, and beaker (i) was stirred.
At the same time, the solution was added from beaker (i) to the polymerizer at a rate of 6.7 g/min over 3 hours. (This operation is to increase the ratio of allyl methacrylate to butyl acrylate linearly from 0.125% to 0.5% in 3 hours.)
At 10, 20, 40 and 60 minutes after the start of monomer addition, 7.7 g of 15.6% beef tallow fatty acid (LUNAC TH manufactured by Kao Corporation) saponified with potassium hydroxide was added. This formed rubber particles. In the rubber particles, the degree of cross-linking increases continuously from the center to the surface of the particles.

(aggregate hypertrophy)
30 minutes after the addition of the monomer was completed, 30 g of a 2% sodium hydroxide aqueous solution was added, 185.8 g of the acid group-containing polymer latex having a solid concentration of 31.5% was added, and 200 g of a 2% sodium hydroxide aqueous solution was added. , and stirred for 60 minutes. As a result, agglomerated enlarged particles of rubber particles were obtained.

(rubber outer layer)
Add a solution of 0.015 g of ferrous sulfate (FeSO ₄ .7H ₂ O) and 0.025 g of disodium ethylenediaminetetraacetate dissolved in 8.0 g of deionized water, add 40.0 g of 5% Rongalit, Stirred for 30 minutes.
A mixture of 100 g of butyl acrylate, 9.0 g of allyl methacrylate, and 0.29 g of 69% t-butyl hydroperoxide was added over 15 minutes, and 0.35 g of 69% t-butyl hydroperoxide was added, followed by stirring for 30 minutes. . Thus, a rubber outer layer was formed to obtain core particles. The particle diameter of the core particles was 700 nm.

(shell layer)
A mixture of 450.0 grams of styrene, 150 grams of acrylonitrile, and 4.4 grams of 69% t-butyl hydroperoxide was added over 120 minutes.
t-Butyl hydroperoxide and Rongalite were appropriately added to form a shell layer to obtain a graft copolymer latex having a conversion rate of 100% and a solid content concentration of 32.3%.

(Example 2)
<Production of graft copolymer latex>
(Rubber particle center layer)
3400 g of deionized water, 64.3 g of saponified potassium hydroxide of 15.6% beef tallow fatty acid (LUNAC TH manufactured by Kao Corporation), and 50 g of 2% sodium carbonate are charged into an 8 L polymerization machine, heated to 50° C., Nitrogen was flowed.

A mixture of 100 g of butyl acrylate, 0.125 g of allyl methacrylate, and 0.26 g of 69% t-butyl hydroperoxide was added to the polymerizer, 0.0108 g of ferrous sulfate _{( FeSO4.7H2O} ), and A solution obtained by dissolving 0.018 g of disodium ethylenediaminetetraacetate in 5.7 g of deionized water was added, and 32.0 g of 5% Rongalite was added, followed by stirring for 30 minutes. The particle size was 35 nm. A mixture of 400 grams of butyl acrylate, 0.5 grams of allyl methacrylate, and 1.0 grams of 69% t-butyl hydroperoxide was then added over 60 minutes. As a result, particles corresponding to the central layer of rubber particles were formed.

(Rubber particle intermediate layer)
A mixture of 400 g butyl acrylate, 1.0 g allyl methacrylate, and 1.0 g 69% t-butyl hydroperoxide was added over 60 minutes. Thus, a rubber particle intermediate layer was formed.

(Rubber particle surface layer)
A mixture of 400 g of butyl acrylate, 2.0 g of allyl methacrylate, and 1.0 g of 69% t-butyl hydroperoxide was added over 60 minutes and stirred for 30 minutes. Thereby, a rubber particle surface layer was formed to obtain a rubber particle having a three-layer structure composed of a rubber particle center layer, a rubber particle intermediate layer, and a rubber particle surface layer. The particle diameter of the rubber particles was 85 nm. In the rubber particles, the degree of cross-linking increases in the order of the rubber particle center layer, the rubber particle intermediate layer, and the rubber particle surface layer.

(aggregate hypertrophy)
30 g of a 2% sodium hydroxide aqueous solution was added, 185.8 g of the acid group-containing polymer latex having a solid concentration of 31.5% was added, and 200 g of a 2% sodium hydroxide aqueous solution was added. As a result, agglomerated enlarged particles of rubber particles were obtained.

(rubber outer layer)
After 60 minutes, a solution of 0.015 g of ferrous sulfate (FeSO ₄ .7H ₂ O) and 0.025 g of disodium ethylenediaminetetraacetate dissolved in 8.0 g of deionized water was added, and 40.0 g of 5% Rongalit was added. was added and stirred for 30 minutes.
A mixture of 100 g of butyl acrylate, 9.0 g of allyl methacrylate, and 0.29 g of 69% t-butyl hydroperoxide was added over 15 minutes, and 0.35 g of 69% t-butyl hydroperoxide was added, followed by stirring for 30 minutes. . Thus, a rubber outer layer was formed to obtain core particles. The particle diameter of the core particles was 700 nm.

(shell layer)
A mixture of 450.0 grams of styrene, 150 grams of acrylonitrile, and 4.4 grams of 69% t-butyl hydroperoxide was added over 120 minutes.
t-Butyl hydroperoxide and Rongalit were added as appropriate to form a shell layer to obtain a graft copolymer latex having a conversion rate of 100% and a solid content concentration of 32.0%.

<Granulation of graft copolymer>
Each graft copolymer latex obtained above was heated to 70° C., and an aqueous calcium chloride solution was added thereto to form a slurry. Then, it was dehydrated with a centrifugal dehydrator, washed with deionized water, and dried at 50°C for 2 days to obtain powder of each graft copolymer.

(Example 3 and Comparative Examples 1 to 12)
In Example 3, a graft copolymer powder was obtained in the same manner as in Example 2, except that the composition was changed according to Table 1.
Comparative Examples 1 to 6 were the same as Example 2 except that the composition was changed according to Table 1 and the core particle size was adjusted by adjusting the amount of the initial saponification product of potassium hydroxide of beef tallow fatty acid. The powder of graft copolymer was obtained by the method.
In Comparative Examples 7 to 10, graft copolymer powder was obtained in the same manner as in Example 2, except that the composition was changed according to Table 1.
In Comparative Examples 11 and 12, graft copolymer powder was obtained in the same manner as in Example 2, except that the composition was changed according to the description in Table 1 and the timing of cohesion and enlargement was changed.

(Method for measuring Izod impact strength)
700 g of the powder of the obtained graft copolymer, 1293 g of AS resin (PN-117, manufactured by Chimei), and 12 g of carbon black masterbatch (AS resin containing 40% of carbon black) were added and extruded. Extruded pellets were obtained by squeezing, and the pellets were injected by injection molding to obtain 1/8 inch bars of 3 mm. Notched Izod impact strength was measured at 23° C. in accordance with JIS K-7110. Table 1 shows the results.

In the table, BA represents butyl acrylate and ALMA represents allyl methacrylate. The blending amount of each monomer is shown in parts by weight based on 100 parts by weight of the total amount of monomers used in the entire graft copolymer. On the other hand, the blending amount of ALMA was shown in percentage with respect to the amount of monomers used in each layer.

From Table 1, it can be seen that Examples 1 to 3 have extremely large values of Izod impact strength as compared with Comparative Examples 1 to 12, and are excellent in impact resistance.
In Examples 1 to 3, rubber particles having a higher degree of cross-linking on the surface than the degree of cross-linking on the inside were agglomerated and enlarged, then a rubber outer layer was formed to obtain core particles, and a core-shell was further provided with a shell layer. It uses type graft copolymer particles.
On the other hand, in Comparative Examples 1 to 3, the degree of cross-linking of the rubber particles was uniform, and the rubber particles were not aggregated and enlarged. Comparative Examples 4 to 6 were obtained without agglomeration and enlargement of rubber particles. In Comparative Examples 7 to 9, the degree of cross-linking of the rubber particles is uniform. In Comparative Example 10, the degree of cross-linking of the rubber particles was uniform, and no rubber outer layer was formed. In Comparative Example 11, the degree of cross-linking of the rubber particles was uniform, the rubber particles were not aggregated and enlarged, and the core particles were aggregated and enlarged after the rubber outer layer was formed. In Comparative Example 12, the rubber particles were not aggregated and enlarged, but the core particles were aggregated and enlarged after the rubber outer layer was formed.

11 Rubber Particle Central Layer 12 Rubber Particle Intermediate Layer 13 Rubber Particle Surface Layer 14 Rubber Outer Layer 15 Shell Layer 21 Rubber Particle 22 Aggregated Enlarged Particle of Rubber Particle 23 Core Particle 24 Core-Shell Type Graft Copolymer Particle

Claims (13)

A core-shell type graft copolymer particle comprising a core particle and a shell layer covering the core particle,
The core particles include aggregated enlarged particles of rubber particles and an outer rubber layer covering the aggregated enlarged particles,
The rubber particles are configured such that the degree of cross-linking on the surface of the particles is higher than the degree of cross-linking on the inside of the particles,
The agglomerated enlarged particles are obtained by aggregating and enlarging the rubber particles with an acid group-containing polymer,
The rubber particles and the rubber outer layer are each formed from an acrylic rubber obtained by polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer,
The core-shell type graft copolymer particle, wherein the shell layer is formed from a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit. 2. The core-shell type graft copolymer particle according to claim 1, wherein the rubber particle is configured such that the degree of cross-linking increases from the center of the particle toward the surface. The rubber particles comprise a rubber particle center layer located in the center of the particle and a rubber particle surface layer located on the surface of the particle,
2. The core-shell type graft copolymer particle according to claim 1, wherein the rubber particle surface layer has a higher degree of cross-linking than the rubber particle center layer. 4. The core-shell type graft copolymer particle according to claim 3, wherein the rubber particle further comprises a rubber particle intermediate layer positioned between the rubber particle central layer and the rubber particle surface layer. The core-shell type graft copolymer particles according to any one of claims 1 to 4, wherein the acid group-containing polymer is a polymer containing a carboxyl group-containing vinyl monomer unit. The core-shell type graft copolymer particle according to any one of claims 1 to 5, wherein the proportion of the core particles in the core-shell type graft copolymer particles is 66 to 90% by weight. The core-shell type graft copolymer particles according to any one of claims 1 to 6, wherein the core particles have a volume average particle diameter of 400 to 1200 nm. A method for producing core-shell type graft copolymer particles comprising a core particle and a shell layer covering the core particle,
a step of polymerizing a monomer component containing an acrylic monomer and a crosslinkable monomer to form rubber particles having a higher degree of crosslinking on the surface of the particles than the degree of crosslinking on the inside of the particles;
a step of aggregating and enlarging the rubber particles with an acid group-containing polymer latex to obtain agglomerated enlarged particles of rubber particles;
In the presence of the aggregated enlarged particles, a monomer component containing an acrylic monomer and a crosslinkable monomer are polymerized to form a rubber outer layer covering the aggregated enlarged particles, and the aggregated enlarged particles and the obtaining a core particle comprising a rubber outer layer;
In the presence of the core particles, a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound is copolymerized to form a shell layer covering the core particles, thereby producing the core-shell type graft copolymer particles. A method for producing core-shell type graft copolymer particles, comprising the step of obtaining. In the step of forming the rubber particles, by increasing the ratio of the crosslinkable monomer to the monomer component over time, the rubber particles have a higher degree of crosslinking from the center to the surface thereof. 9. The method for producing core-shell type graft copolymer particles according to claim 8, which forms particles. In the step of forming the rubber particles, a rubber particle central layer and a rubber having a higher degree of crosslinking than the rubber particle central layer are formed by multi-stage polymerization of a monomer component containing an acrylic monomer and a crosslinkable monomer. 9. The method for producing core-shell type graft copolymer particles according to claim 8, wherein rubber particles containing a particle surface layer are formed. The method for producing core-shell type graft copolymer particles according to any one of claims 8 to 10, wherein the acid group-containing polymer is a polymer containing a carboxyl group-containing vinyl monomer unit. 100 parts by weight of a thermoplastic resin that is a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units, and
A resin composition comprising 10 to 100 parts by weight of the core-shell type graft copolymer particles according to any one of claims 1 to 7. A molded article obtained by molding the resin composition according to claim 12 .

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