JP7708528B2 - Polyorganosiloxane-containing graft copolymer, resin composition using same, and molded article made of same - Google Patents

Description

The present invention relates to a polyorganosiloxane-containing graft copolymer that maintains the inherent rigidity of a thermoplastic resin while improving impact resistance, and that exhibits high color development in molded articles obtained from the thermoplastic resin, resulting in molded articles with excellent appearance.

Thermoplastic resins such as aromatic polycarbonate resins are general-purpose engineering plastics that are excellent in transparency, impact resistance, heat resistance, dimensional stability, etc., and due to their excellent properties, are widely used industrially as materials in the fields of automobiles, office automation equipment, electrical and electronics, etc. In recent years, a method of adding polyester resins, etc. to aromatic polycarbonate resins has been used to improve chemical resistance and fluidity, but the impact resistance is often insufficient,
In order to improve the impact resistance, a method of further adding an impact resistance modifier is used.

Molded products obtained from the above resins are becoming thinner every year, particularly for the purpose of making them smaller, lighter, and more functional, and there is a demand for them to maintain even greater impact resistance and rigidity. In recent years, mainly for applications such as electrical and electronic equipment housings and home appliances, they are sometimes used without painting in order to reduce product costs, and there is a demand for the resin itself to be colored to the desired color tone and for it to have an excellent molded appearance.

For example, Patent Document 1 proposes a silicone/acrylic composite rubber graft copolymer obtained by graft polymerizing one or more vinyl monomers onto a composite rubber containing a polyorganosiloxane rubber and a polyalkyl (meth)acrylate rubber, the polyorganosiloxane content being 15 to 70% by mass, the composite rubber content being 75 to 90% by mass, and the amount of iron charged being 0.0001 to 2 ppm in the graft copolymer latex. However, the graft copolymer described in Patent Document 1 does not have sufficient color development or rigidity.

Patent Document 2 proposes a polyorganosiloxane-containing graft copolymer obtained by polymerizing one or more graft vinyl monomers (b) in the presence of rubber (A) containing polyorganosiloxane and a vinyl polymer, the refractive index of the rubber (A) being within the range of 1.47 to 1.56, and the volume average particle size being within the range of 300 to 2000 nm. However, since the graft copolymer described in Patent Document 2 has a volume average particle size of 300 nm or more, the appearance of the molded product obtained by injection molding is not satisfactory.

JP 2004-34271 A International Publication No. 2014/208716

The object of the present invention is to provide a polyorganosiloxane-containing graft copolymer that imparts impact resistance while maintaining the inherent rigidity of a thermoplastic resin, and that can produce molded articles with excellent color development and molded appearance. Another object of the present invention is to provide a thermoplastic resin composition and molded article that have such properties.

The present invention has the following aspects.
[1] A polyorganosiloxane-containing graft copolymer obtained by graft polymerizing a vinyl monomer (b) onto a rubber (A) containing a polyorganosiloxane (A1) and a vinyl polymer (A2),
Refractive index: 1.47 to 1.60,
The weight average particle size is greater than 50 nm and less than 300 nm.
A polyorganosiloxane-containing graft copolymer containing aromatic vinyl units in the rubber (A) in an amount of more than 30 mass% and not more than 90 mass%, based on a total of 100 mass% of the rubber (A).
[2] The polyorganosiloxane-containing graft copolymer according to [1], wherein the rubber (A) contains an alkyl (meth)acrylate unit.
[3] The rubber (A) contains alkyl (meth)acrylate units in an amount of more than 0 mass% and not more than 30 mass% based on the total 100 mass% of the rubber (A). [1] or [2]. A polyorganosiloxane-containing graft copolymer.
[4] The polyorganosiloxane-containing graft copolymer according to any one of [1] to [3], wherein the content of the polyorganosiloxane (A1) in the polyorganosiloxane-containing graft copolymer is 1 to 50 mass%.
[5] The polyorganosiloxane-containing graft copolymer according to any one of [1] to [4], containing a vinyl-based polymerizable group-containing silane compound in an amount of more than 0.5% by mass and not more than 10% by mass relative to the polyorganosiloxane (A1).
[6] The polyorganosiloxane-containing graft copolymer according to any one of [1] to [5], containing 50 to 100 mass% of (meth)acrylate relative to the vinyl monomer (b).
[7] A resin composition comprising the polyorganosiloxane-containing graft copolymer according to any one of [1] to [6].
[8] The resin composition according to [7], comprising a polycarbonate resin and a polyester resin.
[9] The resin composition according to [8], wherein the polycarbonate resin is an aromatic polycarbonate resin.
[10] The resin composition according to [8] or [9], wherein the polyester resin is an aromatic polyester resin.
[11] A molded article made of the thermoplastic resin composition according to any one of [7] to [10].

According to the present invention, it is possible to provide a polyorganosiloxane-containing graft copolymer that can provide a resin composition and a molded article that are excellent in impact resistance, color development, and molded appearance while maintaining the inherent rigidity of a thermoplastic resin. Furthermore, according to the present invention, it is possible to provide a resin composition and a molded article that have such properties.

The present invention will be described in detail below. In the present invention, "(meth)acrylate" means at least one of "acrylate" and "methacrylate". In the present invention, the polyorganosiloxane-containing graft copolymer may be simply referred to as "graft copolymer".

[Polyorganosiloxane-containing graft copolymer]
The polyorganosiloxane-containing graft copolymer of the present invention (sometimes simply referred to as "graft copolymer") is a polyorganosiloxane-containing graft copolymer obtained by graft polymerizing a vinyl monomer (b) to a rubber (A) containing a polyorganosiloxane (A1) and a vinyl polymer (A2), and is required to have a refractive index of 1.47 to 1.60, a weight average particle diameter of more than 50 nm and less than 300 nm, and to contain more than 30 mass% and not more than 90 mass% of the aromatic vinyl monomer units in the rubber (A) based on a total of 100 mass% of the rubber (A).

"Refractive index measurement"
The polyorganosiloxane-containing graft copolymer formed into a thin film by compression molding is measured at a temperature of 23° C. using an Abbe refractometer in accordance with JIS K 7142 A method.

The graft copolymer of the present invention must have a refractive index of 1.47 to 1.60. A refractive index of 1.47 or more is preferable because a thermoplastic resin composition with excellent color development can be obtained, while a refractive index of 1.60 or less is preferable because a resin composition with excellent low-temperature impact strength can be obtained. The refractive index of the graft copolymer of the present invention can be adjusted to a desired refractive index by adjusting the content of polyorganosiloxane (A1), the type and amount of vinyl polymer (A2) and vinyl monomer (b).

This is because the refractive index of the graft copolymer of the present invention can be predicted as a value calculated using the following formula (Formula 1) described in POLYMER HANDBOOK 4th Edition (Wiley Interscience).

[Formula 1]
n=v ₁ n ₁ +v ₂ n ₂ +v ₃ n ₃ +...
In the formula, " _n1 , _n2 , _n3 , ..." represent the refractive index of a homopolymer of each monomer at 20°C, and the values described in the POLYMER HANDBOOK 4th Edition can be used. In the formula, " _v1 , _v2 , _v3 , ..." represent the volume fraction of each monomer.

The weight average particle diameter of the graft copolymer of the present invention must be greater than 50 nm and less than 300 nm. If it is greater than 50 nm, it is effective in imparting impact resistance when added to a resin, and if it is less than 300 nm, it is difficult for the rigidity to decrease when added to a resin, and it is possible to obtain a molded product with excellent molded appearance without flow marks. The preferred range is greater than 50 nm and not more than 250 nm, more preferably 100 to 250 nm, and even more preferably 100 to 200 nm.

The weight average particle diameter can be determined by the following method. The graft copolymer latex is diluted with deionized water to a concentration of approximately 3%, and the particle diameter is measured using a particle size distribution analyzer CHDF2000 manufactured by MATEC Corporation, USA. The median particle diameter is used as the average particle diameter.

The measurement can be carried out under the following standard conditions recommended by MATEC.
Cartridge: Dedicated capillary cartridge for particle separation (product name: C-202)
Carrier liquid: Dedicated carrier liquid (product name: 2XGR500)
Carrier liquid property: Nearly neutral Carrier liquid flow rate: 1.4 ml/min Carrier liquid pressure: Approximately 4,000 psi (2,600 kPa)
Measurement temperature: 35℃
Amount of sample used: 0.1 ml
The standard particle size substance used is monodisperse polystyrene with known particle sizes manufactured by DUKE Corporation of the United States, and contains 12 types of particles within the particle size range of 40 to 800 nm.

[Polyorganosiloxane (A1)]
Polyorganosiloxane (A1) is a polymer containing an organosiloxane unit in which at least one organic group is bonded to a silicon atom as a constituent unit. Polyorganosiloxane (A1) can be obtained by polymerizing an organosiloxane or an "organosiloxane mixture" containing an organosiloxane and one or more components that are used as needed. Examples of the components that are used as needed include a siloxane crosslinking agent, a siloxane grafting agent, and a siloxane oligomer having a terminal blocking group.

As the organosiloxane, any of chain organosiloxanes, alkoxysilane compounds, and cyclic organosiloxanes can be used. Among these, alkoxysilane compounds and cyclic organosiloxanes are preferred, and cyclic organosiloxanes are more preferred because of their high polymerization stability and high polymerization rate.

As the alkoxysilane compound, a bifunctional alkoxysilane compound is preferable, and examples thereof include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, dimethyldipropoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, etc.

As the cyclic organosiloxane, those having 3 to 7 membered rings are preferred, and examples thereof include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane. These can be used alone or in combination of two or more. Among these, it is preferred that the main component is octamethylcyclotetrasiloxane, since the particle size distribution is easily controlled.

As the organosiloxane, it is preferable to use an organosiloxane that is a cyclic dimethylsiloxane and/or a bifunctional dialkylsilane compound, since this makes it possible to obtain a graft copolymer with higher low-temperature impact resistance.

Cyclic dimethylsiloxanes are cyclic siloxanes that have two methyl groups on the silicon atom, and examples of such cyclic siloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane.

The difunctional dialkylsilane compound is a compound having two alkyl groups among the above-mentioned difunctional alkoxysilane compounds, and examples of such compounds include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, and dimethyldipropoxysilane.
These may be used alone or in combination of two or more.

As the siloxane-based crosslinking agent, one having a siloxy group is preferred. By using a siloxane-based crosslinking agent, a polyorganosiloxane having a crosslinked structure can be obtained. Examples of the siloxane-based crosslinking agent include trifunctional or tetrafunctional silane-based crosslinking agents such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, and tetrabutoxysilane. Among them, a tetrafunctional crosslinking agent is preferred, and tetraethoxysilane is more preferred. The content of the siloxane-based crosslinking agent is preferably 0 to 30 mass%, more preferably 0 to 15 mass%, and more preferably 0 to 5 mass%, in 100 mass% of the organosiloxane mixture. By setting the content of the siloxane-based crosslinking agent to 0 to 30 mass%, a graft copolymer having good low-temperature impact resistance can be obtained.

The vinyl-based polymerizable group-containing silane compound is a siloxane-based graft crosslinking agent, which has a siloxy group and a functional group polymerizable with a vinyl monomer. By using the vinyl-based polymerizable group-containing silane compound, a polyorganosiloxane having a functional group polymerizable with a vinyl monomer can be obtained. Since the polyorganosiloxane has a functional group polymerizable with a vinyl monomer, the polyorganosiloxane can have a chemical bond with the vinyl polymer (A2) described below, and the vinyl monomer (b) can be grafted by radical polymerization, so that a graft copolymer with excellent dispersibility and impact strength can be obtained when added to a resin.

The vinyl-based polymerizable group-containing silane compound may be a siloxane represented by the formula (I).
RSiR ₁ n (OR ₂ ) (3-n) (I)
In formula (I), _R1 represents a methyl group, an ethyl group, a propyl group, or a phenyl group. _R2 represents an organic group in the alkoxy group, such as a methyl group, an ethyl group, a propyl group, or a phenyl group. n represents 0, 1, or 2. R represents any of the groups represented by formulae (I-1) to (I-4).

CH ₂ =C(R ₃ )-COO-(CH ₂ ) _p - (I-1)
CH ₂ =C(R ₄ )-C ₆ H ₄ - (I-2)
CH ₂ =CH- (I-3)
HS-( _CH2 ) _p- (I-4)
In these formulas, R ₃ and R ₄ each represent a hydrogen atom or a methyl group, and p represents an integer of 1 to 6.

The functional group represented by formula (I-1) can be a methacryloyloxyalkyl group. Examples of siloxanes having this group include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylethoxydiethylsilane, γ-methacryloyloxypropyldiethoxymethylsilane, and δ-methacryloyloxybutyldiethoxymethylsilane.

These vinyl-based polymerizable group-containing silane compounds can be used alone or in combination of two or more. The content of the vinyl-based polymerizable group-containing silane compound is preferably more than 0.5 and not more than 10 mass%, more preferably more than 1.0 and not more than 8.0 mass%, and even more preferably more than 2.0 and not more than 8.0 mass%, relative to 100 mass% of the organosiloxane mixture. By containing more than 0.5 and not more than 10 mass% of the vinyl-based polymerizable group-containing silane compound, the chemical bond with the polyorganosiloxane is at a sufficient ratio, and a graft copolymer can be obtained that can provide a resin composition with a good balance between impact resistance and color development.

A siloxane oligomer having a terminal blocking group refers to a siloxane oligomer that has an alkyl group or the like at the end of the organosiloxane oligomer, thereby terminating the polymerization of the polyorganosiloxane.

Examples of siloxane oligomers having terminal blocking groups include hexamethyldisiloxane, 1,3-bis(3-glycidoxypropyl)tetramethyldisiloxane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and siloxane oligomers in which the terminal blocking group is a trimethylsilyl group.

[Method for producing polyorganosiloxane (A1)]
There is no particular limitation on the method for producing polyorganosiloxane (A1), and for example, the following production method can be adopted. First, an organosiloxane mixture containing an organosiloxane, a vinyl-based polymerizable group-containing silane compound, a siloxane-based crosslinking agent if necessary, and a siloxane oligomer having a terminal blocking group if necessary is emulsified with an emulsifier and water to prepare an emulsion. Then, the mixture is polymerized at high temperature using an acid catalyst, and the acid is neutralized with an alkaline substance to obtain a polyorganosiloxane latex. In the following description of the production method, the case where an "organosiloxane mixture" is used as a raw material for polymerization is described, but the same production process can also be applied when "organosiloxane" is used alone.

In this manufacturing method, the emulsion can be prepared by using a homomixer that atomizes the particles using shear forces generated by high-speed rotation, or by mixing the particles by high-speed stirring using a homogenizer that atomizes the particles using the jetting force of a high-pressure generator. Of these, the method using a homogenizer is preferred because it narrows the particle size distribution of the polyorganosiloxane latex.

Methods for mixing the acid catalyst during polymerization include (1) adding the acid catalyst all at once with the organosiloxane mixture, emulsifier, and water, and mixing, (2) adding the acid catalyst aqueous solution all at once to the emulsion of the organosiloxane mixture, and (3) dropping the emulsion of the organosiloxane mixture into a hot aqueous acid catalyst solution at a constant rate and mixing. Because it is easy to control the particle size of the polyorganosiloxane, it is preferable to hold the emulsion of the organosiloxane mixture at a high temperature and then add the acid catalyst aqueous solution all at once to it.

The polymerization temperature is preferably 50°C or higher, and more preferably 70°C or higher. The polymerization time is usually 2 hours or longer, and preferably 5 hours or longer, when the acid catalyst aqueous solution is added all at once to the emulsion of the organosiloxane mixture to polymerize it.

Furthermore, since the crosslinking reaction between silanols proceeds at temperatures below 30°C, in order to increase the crosslink density of the polyorganosiloxane, it is possible to polymerize at a high temperature of 50°C or higher, and then hold the resulting latex at a temperature below 30°C for about 5 to 100 hours.

The polymerization reaction of the organosiloxane mixture can be terminated by neutralizing the reaction system containing the latex to a pH of 6-8 with an alkaline substance such as sodium hydroxide, potassium hydroxide, or an aqueous ammonia solution.

The emulsifier used in the above production method is not particularly limited as long as it is capable of emulsifying the organosiloxane mixture, but anionic emulsifiers or nonionic emulsifiers are preferred.
Examples of the anionic emulsifier include sodium alkylbenzene sulfonate, sodium alkyl diphenyl ether disulfonate, sodium alkyl sulfate, sodium polyoxyethylene alkyl sulfate, and sodium polyoxyethylene nonylphenyl ether sulfate.
Examples of nonionic emulsifiers include the following: polyoxyethylene alkyl ethers, polyoxyethylene alkylene alkyl ethers, polyoxyethylene distyrenated phenyl ethers, polyoxyethylene tribenzyl phenyl ethers, polyoxyethylene polyoxypropylene glycols, and the like.
These emulsifiers may be used alone or in combination of two or more.

The amount of emulsifier used is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the organosiloxane mixture. The particle size of the polyorganosiloxane latex can be adjusted to a desired value by adjusting the amount of emulsifier used. If the amount of emulsifier used is 0.05 parts by mass or more, the emulsion stability of the organosiloxane mixture emulsion is sufficient. If the amount of emulsifier used is 10 parts by mass or less, the amount of emulsifier remaining in the graft copolymer powder can be sufficiently reduced, so that deterioration in the thermal decomposition resistance and surface appearance of the resin composition containing the graft copolymer and a resin can be suppressed.

Acid catalysts used in the polymerization of the organosiloxane mixture include sulfonic acids such as aliphatic sulfonic acid, aliphatic-substituted benzenesulfonic acid, and aliphatic-substituted naphthalenesulfonic acid, as well as mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid. These acid catalysts can be used alone or in combination of two or more. Among these, the use of mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid can narrow the particle size distribution of the polyorganosiloxane latex, and can also reduce the decrease in thermal decomposition resistance and poor appearance of the molded product caused by the emulsifier components in the polyorganosiloxane latex.

The amount of acid catalyst used is preferably 0.005 to 5 parts by mass per 100 parts by mass of organosiloxane. If the amount of acid catalyst used is 0.005 parts by mass or more, polyorganosiloxane can be polymerized in a short time. Furthermore, if the amount of acid catalyst used is 5 parts by mass or less, a molded product with good thermal decomposition resistance and appearance can be obtained.

In addition, since the amount of acid catalyst used is a factor that determines the particle size of the polyorganosiloxane, it is more preferable to use an amount of acid catalyst of 0.005 to 1.5 parts by mass in order to obtain a polyorganosiloxane with a particle size described below.

The weight average particle diameter of the polyorganosiloxane in the latex is not particularly limited, but is preferably within the range of 250 to 1000 nm. By setting the weight average particle diameter of the polyorganosiloxane within the range of 250 to 1000 nm, it is possible to adjust the weight average particle diameter of the rubber (A) within the range of 300 to 2000 nm.

The "weight average particle diameter/number average particle diameter (Dw/Dn)" of the polyorganosiloxane in the latex is preferably within the range of 1.0 to 1.7. By keeping Dw/Dn within the range of 1.0 to 1.7, it is possible to obtain a graft copolymer with high transparency when added to a resin.

The values of Dw and Dn can be measured by the following method. A polyorganosiloxane latex diluted with deionized water to a concentration of about 3% is used as a sample, and the particle size is measured using a CHDF2000 particle size distribution analyzer manufactured by MATEC Corporation in the United States. The median size is used as the average particle size.

The measurement can be carried out under the following standard conditions recommended by MATEC.
Cartridge: Dedicated capillary cartridge for particle separation (product name: C-202)
Carrier liquid: Dedicated carrier liquid (product name: 2XGR500)
Carrier liquid property: Nearly neutral Carrier liquid flow rate: 1.4 ml/min Carrier liquid pressure: Approximately 4,000 psi (2,600 kPa)
Measurement temperature: 35℃
Amount of sample used: 0.1 ml
The standard particle size substance used is monodisperse polystyrene with known particle sizes manufactured by DUKE Corporation of the United States, and contains 12 types of particles within the particle size range of 40 to 800 nm.

To improve the mechanical stability of the polyorganosiloxane latex obtained by the above method, an emulsifier may be added as necessary. As the emulsifier, an anionic emulsifier or a nonionic emulsifier similar to those exemplified above is preferable.

[Vinyl polymer (A2)]
The vinyl polymer (A2) of the present invention is a polymer obtained by polymerizing an aromatic vinyl monomer for rubber (a1) and another monomer component for rubber (a2), the rubber (A) containing more than 30 mass% to 90 mass% or less of aromatic vinyl units, based on 100 mass% of the rubber (A) in total.

[Aromatic vinyl monomer for rubber (a1)]
Examples of the aromatic vinyl monomer for rubber (a1) include styrene, α-methylstyrene, o-, m- or p-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene, p-tert-butylstyrene, ethylstyrene, vinylnaphthalene, and the like. These can be used alone or in combination of two or more.

Among these, the aromatic vinyl unit must be contained in an amount of more than 30% by mass and not more than 90% by mass, based on a total of 100% by mass of the rubber (A). It is preferably more than 40% by mass and not more than 85% by mass, and more preferably more than 60% by mass and not more than 80% by mass. By containing more than 30% by mass of aromatic vinyl units, the color development and rigidity when added to a resin are excellent, and by containing not more than 90% by mass, the impact strength and molded appearance are excellent.

[Other rubber monomer components (a2)]
Examples of other rubber monomer components (a2) include the following monomers: alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and i-butyl methacrylate ; alkyl acrylates such as ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, and 2-ethylhexyl acrylate ; allyl (meth)acrylate; phenyl (meth)acrylate, 4-t-butylphenyl (meth)acrylate, bromophenyl (meth)acrylate, dibromophenyl (meth)acrylate, 2,4,6-tribromophenyl (meth)acrylate, monochlorophenyl (meth)acrylate, dichlorophenyl (meth)acrylate, aryl (meth)acrylates in which the ester group is a phenyl group or a substituted phenyl group, such as trichlorophenyl (meth)acrylate and trichlorophenyl (meth)acrylate; polyfunctional vinyl monomers, such as triallyl cyanurate, triallyl isocyanurate, divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol diester dimethacrylate, 1,4-butylene glycol diester dimethacrylate, 1,6-hexanediol diacrylate, and triallyl trimellitate; cyanide vinyl monomers, such as acrylonitrile and methacrylonitrile. These may be used alone or in combination of two or more.

Among these, it is preferable to contain more than 0 mass% and 30 mass% or less of one or more selected from alkyl (meth)acrylate units and allyl (meth)acrylate units based on a total of 100 mass% of the rubber (A). By containing more than 0 mass% of one or more selected from alkyl (meth)acrylate units and allyl (meth)acrylate units , the impact strength is excellent when added to a resin, and by containing 30 mass% or less, the color development and rigidity are excellent when added to a resin.

The method for producing the vinyl polymer (A2) is not particularly limited, and it can be produced by, for example, emulsion polymerization, suspension polymerization, or fine suspension polymerization, but it is preferable to use the emulsion polymerization method.

As the radical polymerization initiator used for the polymerization of the aromatic vinyl monomer for rubber (a1) and/or the other monomer component for rubber (a2), an azo-based initiator, a peroxide, or a redox-based initiator combining a peroxide and a reducing agent is used. These can be used alone or in combination of two or more. Among these, azo-based initiators and redox-based initiators are preferred.

Examples of azo initiators include the following: Oil-soluble azo initiators such as 2,2'-azobisisobutyronitrile, dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2-butyronitrile); water-soluble azo initiators such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis[N-(2-carboxymethyl)-2-methylpropionamidine]hydrate, 2,2'-azobis-(N,N'-dimethyleneisobutylamidine)dihydrochloride, and 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride. These can be used alone or in combination of two or more.

Examples of peroxides include the following: inorganic peroxides such as hydrogen peroxide, potassium persulfate, and ammonium persulfate; and organic peroxides such as diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, succinic acid peroxide, t-butyl peroxy neodecanoate, t-butyl peroxy neoheptanoate, t-butyl peroxy pivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, and t-butyl peroxy-2-ethylhexanoate. These can be used alone or in combination of two or more.

When a peroxide is combined with a reducing agent to form a redox initiator, it is preferable to use the above-mentioned peroxide in combination with a reducing agent such as sodium formaldehyde sulfoxylate, L-ascorbic acid, fructose, dextrose, sorbose, inositol, and ferrous sulfate/ethylenediaminetetraacetic acid disodium salt. These reducing agents can be used alone or in combination of two or more.

The radical polymerization initiator used in the polymerization of the aromatic vinyl monomer for rubber (a1) and the other monomer component for rubber (a2) preferably has a solubility in water at 20°C of 5% by mass or less, more preferably 2% by mass or less. By carrying out polymerization using this radical polymerization initiator, a graft copolymer with excellent low-temperature impact resistance can be obtained.

Examples of radical polymerization initiators having a solubility in water of 5% by mass or less at 20°C include the following: cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, t-butyl peroxy neodecanoate, t-butyl peroxy neoheptanoate, t-butyl peroxy pivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, 2,2'-azobisisobutyronitrile, dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-butyronitrile), etc. These can be used alone or in combination of two or more.

The solubility of radical polymerization initiators in water at 20°C can be found in catalogs of various radical polymerization initiators.

When using an azo-based initiator, the amount of radical polymerization initiator used is preferably 0.01 to 1 part by mass per 100 parts by mass of the total monomers. When using a redox-based initiator, the amount of peroxide used is preferably 0.01 to 1 part by mass per 100 parts by mass of the total monomers. From the viewpoint of outgassing resistance, the amount of reducing agent used is preferably 0.01 to 1 part by mass per 100 parts by mass of the total monomers.

[Rubber (A)]
The rubber (A) contains a polyorganosiloxane (A1) and a vinyl polymer (A2). Examples of the rubber (A) include rubbers having the following structures (1) to (5).
(1) A rubber having a multilayer structure in which a core of a polyorganosiloxane (A1) is covered with a shell of a vinyl polymer (A2);
(2) A rubber having a multi-layer structure in which a core of a vinyl polymer (A2) is covered with a shell of a polyorganosiloxane (A1);
(3) A composite rubber having a structure in which a polyorganosiloxane (A1) and a vinyl polymer (A2) are interposed between each other.
(4) A composite rubber having an islands-in-sea structure in which the polyorganosiloxane (A1) constitutes the islands and the vinyl polymer (A2) constitutes the sea.
(5) A composite rubber having an island-sea structure in which the polyorganosiloxane (A1) constitutes the sea and the vinyl polymer (A2) constitutes the islands.
Among these, rubber having the structure (5) is preferred, and is particularly excellent in impact strength and rigidity when the graft copolymer is added to a resin.

The content of polyorganosiloxane (A1) is preferably 1 to 50% by mass, more preferably 5 to 35% by mass, and even more preferably 10 to 30% by mass, based on 100% by mass of the polyorganosiloxane-containing graft copolymer. By making it 1% by mass or more, the impact strength when the graft copolymer is added to the resin is excellent, and by making it 50% by mass or less, the color development, rigidity, and molded appearance are excellent.

There are no particular limitations on the method for producing rubber (A), and it can be produced, for example, by emulsion polymerization, suspension polymerization, or fine suspension polymerization, but it is preferable to use emulsion polymerization. Among these, it is preferable that rubber (A) has the structure (5) described above. As a method for obtaining a rubber having the structure (5), there is a method of polymerizing (a1) and/or (a2) in the presence of polyorganosiloxane rubber. Specifically, first, (a1) and/or (a2) are added to the latex of polyorganosiloxane rubber, and the polyorganosiloxane is impregnated with the rubber, and then polymerized using a known radical polymerization initiator. In this method, the method for adding (a1) and/or (a2) includes a method of adding the entire amount of the rubber to the polyorganosiloxane latex at once, a method of adding the entire amount of the rubber in portions at a constant rate by dropping the amount at a constant rate, and a method of adding a portion of the rubber at once and dropping the remaining amount at a constant rate. Among these, the method of adding a portion of (a1) and/or (a2) all at once and adding the remainder dropwise at a constant rate is preferred because it allows for easy control of the polymerization and produces a graft copolymer that has excellent impact strength when added to a resin.

When producing a latex of rubber (A), an emulsifier can be added to stabilize the latex and control the particle size of rubber (A). Examples of emulsifiers include the same emulsifiers as those used when producing a latex of polyorganosiloxane, and anionic emulsifiers and nonionic emulsifiers are preferred.

The weight average particle diameter (Dw) of rubber (A) is not particularly limited, but is preferably 10 nm to 290 nm. If the weight average particle diameter of rubber (A) is 10 nm or more, it will have excellent impact strength when added to a resin, and if it is 290 nm or less, it will have excellent rigidity and molded appearance, which is preferable.

[Vinyl Monomer (b)]
A polyorganosiloxane-containing graft copolymer can be obtained by polymerizing a vinyl monomer (b) in the presence of the rubber (A) to form a graft portion made of a vinyl polymer on the rubber (A).

Examples of the vinyl monomer (b) include the following: aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyl toluene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and i-butyl methacrylate; alkyl acrylates such as ethyl acrylate, n-butyl acrylate, and methyl acrylate; cyanide vinyl monomers such as acrylonitrile and methacrylonitrile; aryl (meth)acrylates in which the ester group is a phenyl group or a substituted phenyl group, such as phenyl (meth)acrylate, 4-t-butylphenyl (meth)acrylate, bromophenyl (meth)acrylate, dibromophenyl (meth)acrylate, 2,4,6-tribromophenyl (meth)acrylate, monochlorophenyl (meth)acrylate, dichlorophenyl (meth)acrylate, and trichlorophenyl (meth)acrylate. These can be used alone or in combination of two or more. Among these, (meth)acrylate is preferable, alkyl methacrylate is more preferable, and methyl methacrylate is even more preferable. When (meth)acrylate is used as the vinyl monomer (b), it has excellent compatibility with the resin, and when added to the resin, it has excellent impact strength and molded appearance.

When a (meth)acrylate is used as the vinyl monomer (b), its content is preferably 50 to 100% by mass relative to (b), and more preferably 75 to 100% by mass. When the (meth)acrylate content is 50% by mass or more relative to (b), it is preferred since it has better compatibility with the resin and provides better impact strength and molded appearance when added to the resin.

The vinyl monomer (b) may contain a crosslinkable monomer, but in that case, the amount of the crosslinkable monomer used in 100% by mass of the vinyl monomer (b) is preferably 0.005% by mass or less.

The content of rubber (A) in the graft copolymer is preferably 10 to 99% by mass relative to 100% by mass of the graft copolymer. If the content of rubber (A) is 10% by mass or more, the impact strength of the resin composition will be sufficient, and if it is 99% by mass or less, it will have excellent dispersibility in the resin and a good molded appearance, which is preferable.

As a method of graft copolymerization, for example, a method of adding vinyl monomer (b) to a latex of rubber (A) and polymerizing in one stage or multiple stages can be mentioned. When polymerizing in multiple stages, it is preferable to polymerize by dividing the total amount of vinyl monomer (b) used in the presence of latex of rubber (A) and adding it successively or continuously. Such a polymerization method has good polymerization stability and can stably obtain a latex having the desired particle size and particle size distribution.

During polymerization of the graft portion, an emulsifier can be added as necessary. The emulsifier used in polymerization of the graft portion can be the same as the emulsifier used in producing the rubber (A), and anionic emulsifiers and nonionic emulsifiers are preferred.

When recovering graft copolymer powder from the graft copolymer latex, either the spray drying method or the coagulation method can be used.

In the spray drying method, the graft copolymer latex is sprayed in the form of fine droplets in a dryer, and then dried by applying a heated gas for drying. Methods for generating fine droplets include, for example, a rotating disk type, a pressure nozzle type, a two-fluid nozzle type, and a pressurized two-fluid nozzle type. The capacity of the dryer may be anything from a small capacity for laboratory use to a large capacity for industrial use. The temperature of the heating gas for drying is preferably 200°C or less, more preferably 120 to 180°C. Two or more types of graft copolymer latexes produced separately can be spray-dried together. Furthermore, in order to improve powder properties such as blocking during spray drying and bulk density, optional components such as silica can be added to the graft copolymer latex and then spray-dried.

The coagulation method involves coagulating the latex of the graft copolymer, separating the graft copolymer, recovering it, and drying it. First, the latex of the graft copolymer is poured into hot water in which a coagulant has been dissolved, and the graft copolymer is separated by salting out and coagulating it. Next, the separated wet graft copolymer is recovered with a reduced water content by dehydrating, etc. The recovered graft copolymer is dried using a squeeze dehydrator or hot air dryer.

Examples of coagulants include inorganic salts such as aluminum chloride, aluminum sulfate, sodium sulfate, magnesium sulfate, sodium nitrate, and calcium acetate, and acids such as sulfuric acid, with calcium acetate being particularly preferred. These coagulants can be used alone or in combination of two or more, but when using two or more, it is necessary to select a combination that does not form a water-insoluble salt. For example, the combined use of calcium acetate and sulfuric acid or its sodium salt is not preferred because it will form a water-insoluble calcium salt.

The coagulant is usually used as an aqueous solution. The concentration of the aqueous coagulant solution is preferably 0.1% by mass or more, particularly 1% by mass or more, from the viewpoint of stably coagulating and recovering the graft copolymer. In addition, from the viewpoint of reducing the amount of coagulant remaining in the recovered graft copolymer and preventing deterioration of the molded appearance of the molded product, the concentration of the aqueous coagulant solution is preferably 20% by mass or less, particularly 15% by mass or less. The amount of the aqueous coagulant solution is not particularly limited, but is preferably 10 parts by mass or more and 500 parts by mass or less per 100 parts by mass of latex.

The method of contacting the latex with the aqueous coagulant solution is not particularly limited, but typically includes the following methods: (1) A method in which latex is continuously added to the aqueous coagulant solution while stirring it and the solution is maintained for a certain period of time, (2) A method in which the aqueous coagulant solution and latex are continuously poured into a container equipped with a stirrer at a certain ratio while being brought into contact with each other, and a mixture containing the coagulated polymer and water is continuously withdrawn from the container. The temperature when the latex is brought into contact with the aqueous coagulant solution is not particularly limited, but it is preferably 30°C or higher and 100°C or lower. The contact time is not particularly limited.

The coagulated graft copolymer is washed with 1 to 100 times the mass of water, and the wet graft copolymer separated by filtration is dried using a fluidized bed dryer or a squeeze dehydrator. The drying temperature and drying time can be determined appropriately depending on the graft copolymer obtained. It is also possible to directly send the graft copolymer discharged from the squeeze dehydrator or extruder to an extruder or molding machine that produces a resin composition without recovering it, and mix it with a thermoplastic resin to obtain a molded product.

In the present invention, the graft copolymer is preferably recovered using a coagulation method from the viewpoint of the thermal decomposition resistance of the resin composition obtained by mixing the graft copolymer with the thermoplastic resin.

[Thermoplastic resin composition]
The "graft copolymer" used in the thermoplastic resin composition of the present invention can be mixed with a thermoplastic resin to form a thermoplastic resin composition. In the following description, the polyorganosiloxane-containing graft copolymer may be simply referred to as the "graft copolymer."

The thermoplastic resin that can be used in the present invention is not particularly limited, but examples include one or more resins selected from thermoplastic resins and thermoplastic elastomers.

[Thermoplastic resin]
Examples of thermoplastic resins include the following: olefin-based resins such as polypropylene (PP) and polyethylene (PE); styrene (St)-based resins such as polystyrene (PS), high impact polystyrene (HIPS), (meth)acrylate-styrene copolymer (MS), styrene-acrylonitrile copolymer (SAN), styrene-maleic anhydride copolymer (SMA), acrylonitrile-butadiene-styrene copolymer (ABS), acrylic acid ester-styrene-acrylonitrile copolymer (ASA), and acrylonitrile-ethylene-propylene rubber-styrene copolymer (AES); acrylic (Ac)-based resins such as polymethyl methacrylate (PMMA); polycarbonate (PC) resins; polyamide (PA) resins; polyester (PEs) resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); (modified) polyphenylene ether ((m-)PPE) resins, polyoxymethylene engineering plastics such as polyolefin (POM) resin, polysulfone (PSO) resin, polyarylate (PAr) resin, polyphenylene (PPS) resin, etc.; thermoplastic polyurethane (PU) resin; polyvinyl chloride (PVC) resins such as rigid polyvinyl chloride resin, semi-rigid polyvinyl chloride resin, and flexible polyvinyl chloride resin; alloys of PC resin and St resin such as PC/ABS; alloys of PVC resin and St resin such as PVC/ABS; PVC resins such as PA/ABS, etc. Alloys of A resin and St-based resin; alloys of PA resin and thermoplastic elastomer (TPE); alloys of PA resin and polyolefin-based resin such as PA/PP; alloys of PC resin and PEs resin such as PC/PBT; alloys of olefin-based resins such as PP/TPE and PP/PE; alloys of PPE-based resin and other resins such as PPE/HIPS, PPE/PBT, PPE/PA; alloys of PVC-based resin and acrylic resin such as PVC/PMMA, etc.

Examples of thermoplastic elastomers include the following: styrene-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, fluorine-based elastomers, 1,2-polybutadiene, trans-1,4-polyisoprene, etc. Among these, urethane-based elastomers, polyester-based elastomers, and polyamide-based elastomers are preferred.

Among the above-mentioned thermoplastic resins, the following are preferred: St-based resin, PC resin, PA resin, PET resin, PBT resin, (m-)PPE resin, POM resin, PU resin, alloys of PC resin and St-based resin such as PC/ABS, alloys of PA resin and St-based resin such as PA/ABS, alloys of PA resin and TPE, alloys of PA resin and polyolefin-based resin such as PA/PP, alloys of PC resin and PEs resin such as PC/PBT, alloys of PPE-based resin such as PPE/PBT and PPE/PA with other resins, etc.

Furthermore, among the above-mentioned resins, resins containing polycarbonate resins and polyester resins are preferred because they can significantly exert the effects of the present invention.

Aromatic polycarbonate resin is preferable as the polycarbonate resin from the viewpoint of heat resistance and impact resistance. Aromatic polycarbonate resin is a thermoplastic aromatic polycarbonate polymer or copolymer, which may be branched, obtained by reacting an aromatic hydroxy compound or a small amount of a polyhydroxy compound with phosgene or a diester of carbonic acid. The method for producing aromatic polycarbonate resin is not particularly limited, and known methods, such as the phosgene method (interfacial polymerization method) and the melting method (ester exchange method), are used. In the present invention, aromatic polycarbonate resin produced by the melting method and having an adjusted amount of OH groups at the terminals can also be used.

Examples of aromatic polycarbonate resins include the following: Iupilon (registered trademark) S-1000, S-2000, S-3000, H-3000, or H-4000 (manufactured by Mitsubishi Engineering Plastics Corporation), or Panlite (registered trademark) L1250, L1225, or K1300 (manufactured by Teijin Chemicals Limited), etc.

The polyester resin is preferably an aromatic polyester resin, and more preferably a polybutylene terephthalate resin, which has an excellent balance of heat resistance, fluidity, and chemical resistance. Examples of the polybutylene terephthalate resin include those commercially available under the trade names "Trecon" manufactured by Toray Industries, Inc., "NovaDuran" manufactured by Mitsubishi Engineering Plastics Corporation, and "Duranex" manufactured by Polyplastics Co., Ltd.
Moreover, the polybutylene terephthalate resin can be obtained by polymerization using a known method, for example, by dehydration condensation of terephthalic acid or its alkyl diester with 1,4-butanediol using a known method.

The content of the graft copolymer in the total of 100% by mass of the thermoplastic resin and the graft copolymer is preferably 0.5 to 50% by mass, and more preferably 1 to 20% by mass. If the content of the graft copolymer is 0.5% by mass or more, a resin composition with excellent impact resistance can be obtained, and if it is 50% by mass or less, a resin composition with excellent color development, molded appearance, and rigidity can be obtained.

[Additives]
The thermoplastic resin composition may contain various additives within the scope of the present invention, such as stabilizers such as phenol-based stabilizers, phosphorus-based stabilizers, ultraviolet absorbers, and amine-based light stabilizers; flame retardants such as phosphorus-based, bromine-based, silicone-based, and organometallic salt-based; modifiers for imparting various physical properties such as hydrolysis resistance; fillers such as titanium oxide and talc; dyes and pigments; and plasticizers.

Examples of additives that can be used include the following: flame retardants, anti-drip agents (e.g., fluorinated polyolefins, silicones, and aramid fibers), lubricants, release agents (e.g., pentaerythritol tetrastearate), nucleating agents, antistatic agents, stabilizers, fillers, reinforcing agents (e.g., glass fibers, carbon fibers, mica, kaolin, talc, CaCO3, and glass flakes), dyes and pigments. Dyes and pigments include inorganic pigments such as iron oxide, ultramarine, titanium oxide, and carbon black. Organic pigments include blue pigments such as phthalocyanine and anthraquinone, red pigments such as perylene and quinacridone, and yellow pigments such as isoindolinone. Special pigments include fluorescent pigments, metal powder pigments, and pearl pigments. Dyes include nigrosine, perinone, and anthraquinone dyes, and various grades according to the required color are commercially available, and these can be used. These can be used alone or in combination of two or more.

[Method for preparing resin composition]
The method for preparing the thermoplastic resin composition of the present invention is not particularly limited, but the composition can be prepared by mixing and dispersing the graft copolymer, the thermoplastic resin, and various additives used as necessary using a V-type blender, a Henschel mixer, or the like, and melt-kneading the mixture using an extruder or a kneader such as a Banbury mixer, a pressure kneader, or a roll. The mixing of each of these components can be carried out batchwise or continuously, and the mixing order of each component is not particularly limited. The melt-kneaded product can be made into pellets and used for various moldings.

[Molded body]
The molded article according to the present invention is obtained by molding the above-mentioned thermoplastic resin composition. Examples of the method for molding the thermoplastic resin composition include a method for molding the thermoplastic resin composition or a mixture of the graft copolymer powder and a thermoplastic resin with an injection molding machine.

There are no particular limitations on the uses of the molded bodies, and they can be widely used industrially as materials in the automotive, office automation equipment, electrical and electronics fields, etc.

The present invention will be specifically described below with reference to examples and comparative examples. Prior to the examples, various evaluation methods and polyorganosiloxane latex production examples 1 and 2 will be described. Examples 1 and 2 and comparative examples 1 to 3 are examples relating to the production and evaluation of graft copolymers, while Examples 3 and 4 and comparative examples 4 to 7 are examples relating to the production and evaluation of thermoplastic resin compositions. In the production examples and examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[Evaluation method]
(1) Solid Content A mass w1 of polyorganosiloxane latex is dried in a hot air dryer at 180° C. for 30 minutes, and the mass _w2 of the residue after drying is measured, and the solid content [%] is calculated by the following formula.
Solid content [%] = _w2 / _w1 × 100

(2) Mass average particle diameter (Dw)
The "rubber latex" or the "graft copolymer latex" is diluted with deionized water to a solid content concentration of about 3%, and the sample is used to measure the particle size and mass average particle size Dw using the above-mentioned CHDF2000 type particle size distribution analyzer manufactured by MATEC Corporation, USA, under the above-mentioned conditions.

(3) Charpy impact strength In accordance with JIS K 7111-1/1eA, a V-notch is made on a test piece 1 (length 80.0 mm × width 10.0 mm × thickness 4 mm) obtained by injection molding at temperatures of 23 ° C. and -30 ° C., and the Charpy impact strength is measured using a 4J hammer.

(4) Color development (pigment coloring)
Test piece 2 (length 100.0 mm, width 50.0 mm, thickness 2.0 mm) obtained by injection molding was measured for object color according to JIS Z 8729 (Method of expressing object color according to L*a*b* color system) and according to JIS Z 8722 using SE-4000 (product name) manufactured by Nippon Denshoku Industries Co., Ltd., under the following "Measurement Condition 2", and L* is an index of color development. The lower the L*, the better the jet blackness and the better the color development when a pigment is added.
"Measurement condition 2"
Apparatus: Spectroscopic color difference meter SE-4000 (manufactured by Nippon Denshoku Industries Co., Ltd., 0-45° post-spectroscopic method),
Measurement range: 380-780 nm,
Measurement light source: C light (2° field of view)
Measurement method: Reflection method

(5) Molding Appearance Test piece 2 is prepared under the following "molding conditions", and flow marks (striped patterns seen near the gate of a molded article) appearing near the gate of test piece 2 are visually observed.
"Molding conditions" Cylinder temperature: 260°C, mold temperature: 60°C, injection speed: 80mm/s
"Judgment method" Visually judge the appearance of the gate. (○: Flow marks are not noticeable, ×: Flow marks are noticeable)

(6) Bending properties (rigidity)
Measurements are performed at a temperature of 23° C. and a test speed of 2 mm/min using a test piece (length 80.0 mm × width 10.0 mm × thickness 4 mm) in accordance with JIS K 7171. Higher flexural modulus and maximum point strength indicate better rigidity.

[Production Example 1]
2 parts of tetraethoxysilane (TEOS), 2 parts of γ-methacryloyloxypropyldimethoxymethylsilane (DSMA), and 96 parts of a cyclic organosiloxane mixture (manufactured by Shin-Etsu Silicone Co., Ltd., product name: DMC, a mixture of cyclic organosiloxanes having 3 to 6 rings) were mixed to obtain 100 parts of an organosiloxane mixture. An aqueous solution in which 0.67 parts of sodium dodecylbenzenesulfonate (DBSNa) and 0.67 parts of dodecylbenzenesulfonic acid (DBSH) were dissolved in 200 parts of deionized water was added to the mixture, and the mixture was stirred at 10,000 rpm for 5 minutes with a homomixer, and then passed through a homogenizer twice at a pressure of 20 MPa to obtain a stable premixed emulsion.

The emulsion was then placed in a 5-liter separable flask equipped with a cooling condenser, and the aqueous solution was heated to 80°C and held for 5 hours to allow a polymerization reaction. It was then cooled to room temperature (25°C) and held for 12 hours, after which a 5% aqueous solution of sodium hydroxide was added to neutralize the reaction solution to a pH of 7.0, yielding polyorganosiloxane latex (S-1).

The solid content of the polyorganosiloxane latex (AS-1) was 29.2% by mass. The number average particle diameter (Dn) of this latex measured by a capillary particle size distribution analyzer was 98 nm, the weight average particle diameter (Dw) was 204 nm, and the Dw/Dn was 2.1.

[Production Example 2]
2 parts of tetraethoxysilane (TEOS), 2 parts of γ-methacryloyloxypropyldimethoxymethylsilane (DSMA), and 96 parts of octamethylcyclotetrasiloxane (product name: TSF404, manufactured by Momentive Performance Materials Japan, Inc.) were mixed to obtain 100 parts of an organosiloxane mixture. An aqueous solution in which 1 part of sodium dodecylbenzenesulfonate (DBSNa) was dissolved in 150 parts of deionized water was added to the mixture, and the mixture was stirred at 10,000 rpm for 5 minutes with a homomixer, and then passed through a homogenizer twice at a pressure of 20 MPa to obtain a stable premixed emulsion.

The emulsion was then placed in a 5-liter separable flask equipped with a cooling condenser, and heated to 80°C. A mixture of 0.20 parts of sulfuric acid and 49.8 parts of distilled water was then continuously added over a period of 3 minutes. The mixture was maintained at 80°C for 7 hours to carry out a polymerization reaction, and then cooled to room temperature (25°C). The resulting reaction product was then held at room temperature (25°C) for 6 hours. A 5% aqueous solution of sodium hydroxide was then added to neutralize the reaction solution to a pH of 7.0, yielding polyorganosiloxane latex (AS-2).

The solid content of the polyorganosiloxane latex (AS-2) was 29.8% by mass. The number average particle diameter (Dn) of this latex measured by a capillary particle size distribution analyzer was 384 nm, the weight average particle diameter (Dw) was 403 nm, and the Dw/Dn was 1.1.

[Example 1]
102.74 parts of the polyorganosiloxane latex (AS-1) obtained in Production Example 1 (30.0 parts in terms of polymer) was collected in a 5-liter separable flask, and 160 parts of deionized water was added and mixed. Next, a mixture of 14.75 parts of styrene (St), 0.25 parts of allyl methacrylate (AMA), and 0.07 parts of cumene hydroperoxide (CHP) (1/4 amount of the mixture used for rubber polymerization) was added to the separable flask, and stirring was continued for 1 hour at 25°C to impregnate the polyorganosiloxane.

A nitrogen stream was passed through the separable flask to replace the atmosphere in the flask with nitrogen, and the liquid temperature was raised to 70°C. When the liquid temperature reached 70°C, an aqueous solution of 0.001 parts of ferrous sulfate (Fe), 0.003 parts of disodium ethylenediaminetetraacetate (EDTA), and 0.24 parts of sodium formaldehyde sulfoxylate (SFS) in 10 parts of deionized water was added to initiate radical polymerization. After holding for 30 minutes from the start of radical polymerization, a solution of 44.25 parts of styrene (St), 0.75 parts of allyl methacrylate (AMA), and 0.21 parts of cumene hydroperoxide (CHP) was added dropwise over 120 minutes.

In order to complete the polymerization of the vinyl monomer component, the temperature was maintained at 70°C for one hour after the end of the dropping, and a rubber latex containing polyorganosiloxane and styrene was obtained.

With the liquid temperature of this latex at 70°C, a mixture of 9.5 parts of methyl methacrylate (MMA), 0.5 parts of butyl acrylate (BA), and 0.05 parts of t-butyl hydroperoxide (t-BH) was added dropwise to this latex over one hour to initiate and continue the graft polymerization reaction. After the addition was completed, the temperature was kept at 70°C for one hour and then cooled to 25°C to obtain a latex of polyorganosiloxane-containing graft copolymer (G-1).

Next, 500 parts of an aqueous solution with a calcium acetate concentration of 1% by mass was heated to 85°C, and while stirring, 340 parts of the latex of graft copolymer (G-1) was gradually dropped into the aqueous solution to coagulate. The resulting graft copolymer (G-1) was filtered, washed, dehydrated, and then dried to obtain a powder of graft copolymer (G-1). The polymerization rate and weight average particle size of graft copolymer (G-1) are shown in Table 1. Note that this polymerization rate is the polymerization rate of the monomer components used in all processes from the production of the composite rubber to graft polymerization.

[Example 2, Comparative Examples 1 and 2]
Polyorganosiloxane-containing graft copolymers (G-2, and G'-1, 2) were produced in the same manner as in Example 1, except that the types and amounts of the raw materials used in Example 1 were changed to the conditions shown in Table 1, and further, powders of the graft copolymers were obtained. The polymerization rate and mass average particle size of each of the obtained graft copolymers are shown in Table 1. In addition, the peak temperature of tan δ measured under the measurement condition 1 is also shown in Table 1. In addition, the numerical values in parentheses in the columns of monofunctional vinyl monomer (a1) and polyfunctional vinyl monomer (a2) in Table 1 indicate the composition ratio (mass%) in 100 mass% of vinyl polymer (A2). In addition, the refractive index measured by an Abbe refractometer is also shown in Table 1.

[Comparative Example 3]
106.16 parts of the polyorganosiloxane latex (AS-1) obtained in Production Example 1 (31.0 parts in terms of polymer) was collected in a 5-liter separable flask, and 160 parts of deionized water was added and mixed. Next, a mixture of 56.6 parts of butyl acrylate (BA), 1.4 parts of allyl methacrylate (AMA), and 0.05 parts of t-butyl hydroperoxide (t-BH) was added to the separable flask, and stirring was continued for 1 hour at 25°C to impregnate the polyorganosiloxane.

The atmosphere in the separable flask was replaced with nitrogen by passing a nitrogen gas flow through the flask, and the liquid temperature was raised to 45°C. When the liquid temperature reached 45°C, an aqueous solution of 0.001 parts of ferrous sulfate (Fe), 0.003 parts of disodium ethylenediaminetetraacetate (EDTA), and 0.24 parts of sodium formaldehyde sulfoxylate (SFS) dissolved in 10 parts of deionized water was added to initiate radical polymerization. After the radical polymerization was initiated, the liquid temperature was maintained at 60°C for 60 minutes in order to complete the polymerization of the vinyl monomer component, and a rubber latex containing polyorganosiloxane and butyl acrylate was obtained.

With the liquid temperature of this latex at 60°C, a mixture of 10.5 parts of methyl methacrylate (MMA), 0.5 parts of butyl acrylate (BA), and 0.05 parts of t-butyl hydroperoxide (t-BH) was added dropwise to this latex over one hour to initiate and continue the graft polymerization reaction. After the addition was completed, the temperature was kept at 60°C for one hour and then cooled to 25°C to obtain a latex of polyorganosiloxane-containing graft copolymer (G'-3).

Next, 500 parts of an aqueous solution with a calcium acetate concentration of 1% by mass was heated to 40°C, and while stirring, 340 parts of the latex of graft copolymer (G'-3) was gradually dropped into the aqueous solution to coagulate. The resulting graft copolymer (G'-3) was filtered, washed, dehydrated, and then dried to obtain a powder of graft copolymer (G'-3). The polymerization rate and weight average particle size of graft copolymer (G'-3) are shown in Table 1. Note that this polymerization rate is the polymerization rate of the monomer components used in all processes from the production of the composite rubber to graft polymerization.

The abbreviations in Table 1 are as follows.
St: styrene BA: n-butyl acrylate AMA: allyl methacrylate MMA: methyl methacrylate

[Examples 3 and 4 , Comparative Examples 4 to 7 ]
Each of the polyorganosiloxane-containing graft copolymers (G-1) to (G-2), (G'-1) to (G'- 3 ) powders, polybutylene terephthalate resin (manufactured by Mitsubishi Engineering Plastics Corporation, trade name: Novaduran 5010R5), and carbon black (manufactured by Mitsubishi Chemical Corporation, trade name: Carbon Black #960B) were blended and mixed in the ratios shown in Table 2. The blend was dried at 120°C for 12 hours, and then fed to a 30 mmΦ twin-screw extruder (L/D = 30) and melt-mixed and extruded at a cylinder temperature of 260°C and a screw rotation speed of 150 rpm to obtain pellets of thermoplastic resin compositions (H-1) to (H-7).

The pellets obtained were dried at 120°C for 12 hours, then fed into a 100t injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name: SE-100DU) and injection molded at a cylinder temperature of 260°C and a mold temperature of 60°C to obtain "test piece 1" (length 80 mm, width 10 mm, thickness 4 mm) and "test piece 2" (length 100 mm, width 50 mm, thickness 2 mm). For test piece 1, a V-notch was cut using a notching machine in accordance with JIS K 7111-1A for the Charpy impact test. Next, the Charpy impact strength, color development, molded appearance, and bending properties were measured using each test piece. The evaluation results are shown in Table 2.

[Comparison of resin composition performance]
Examples 3 and 4 were excellent in balance of impact strength, color development and bending properties, and had good molded appearance.

In Comparative Examples 4 and 5 , the weight average particle size of the graft copolymer was 300 nm or more, so that the rigidity was poor. In addition, flow marks were noticeable, and the molded appearance was poor.

In Comparative Example 6 , the graft copolymer had a low refractive index and contained less than 30% by mass of aromatic vinyl units, and therefore was inferior in rigidity and, in particular, in color development.

Comparative Example 7 , which did not contain a graft copolymer, was poor in impact strength.

Claims (10)

A polyorganosiloxane-containing graft copolymer obtained by graft polymerizing a vinyl monomer (b) onto a rubber (A) containing a polyorganosiloxane (A1) and a vinyl polymer (A2),
Refractive index: 1.52 to 1.60;
The weight average particle size is greater than 50 nm and less than 300 nm.
The rubber (A) contains aromatic vinyl units in an amount of more than 60 mass% and not more than 80 mass%, based on a total of 100 mass% of the rubber (A),
A polyorganosiloxane-containing graft copolymer containing 75 to 100% by mass of (meth)acrylate relative to the vinyl monomer (b). The polyorganosiloxane-containing graft copolymer according to claim 1, wherein the rubber (A) contains at least one selected from the group consisting of alkyl (meth)acrylate units and allyl (meth)acrylate units . The rubber (A) contains more than 0 mass% and 30 mass% or less of one or more selected from alkyl (meth)acrylate units and allyl (meth)acrylate units , based on a total of 100 mass% of the rubber (A). The polyorganosiloxane-containing graft copolymer according to any one of claims 1 to 2. The polyorganosiloxane-containing graft copolymer according to any one of claims 1 to 3, wherein the content of the polyorganosiloxane (A1) in the polyorganosiloxane-containing graft copolymer is 5 to 35 mass%. The polyorganosiloxane-containing graft copolymer according to any one of claims 1 to 4, containing more than 0.5% by mass and not more than 10% by mass of structural units derived from a vinyl-based polymerizable group-containing silane compound relative to the polyorganosiloxane (A1). A resin composition comprising the polyorganosiloxane-containing graft copolymer according to any one of claims 1 to 5. The resin composition according to claim 6, which contains a polycarbonate resin and a polyester resin. The resin composition according to claim 7, wherein the polycarbonate resin is an aromatic polycarbonate resin. The resin composition according to claim 7 or 8, wherein the polyester resin is an aromatic polyester resin. A molded article made of the thermoplastic resin composition according to any one of claims 7 to 9.