JP2021021028A - Method for producing rubber graft copolymer - Google Patents

Abstract

To provide a method for producing a rubber graft copolymer excellent in thermal stability by emulsion polymerization.SOLUTION: The method for producing a rubber graft copolymer includes the steps of: graft-polymerizing a vinyl monomer component onto a rubbery polymer by emulsion polymerization to obtain a latex containing a rubber graft copolymer; adding a polyaminocarboxylate or phytic acid as a metal complexing agent to the latex; adding a salt comprising a strong acid and a strong base to the latex to coagulate the rubber graft copolymer; and drying the rubber graft copolymer.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a rubber graft copolymer using emulsion polymerization.

Conventionally, as a technique for improving the impact resistance of a thermoplastic resin, a method of blending a graft copolymer containing a rubber component such as polybutadiene or acrylic rubber into the thermoplastic resin has been known.

In producing such a graft copolymer, rubber-like polymer particles are formed by emulsion polymerization, and a vinyl monomer is graft-polymerized to form a latex containing the graft copolymer. A general method is to add a coagulant such as sulfuric acid to coagulate the rubber graft copolymer, and then dehydrate and dry it to recover it as a powder.

Patent Document 1 contains an aromatic vinyl monomer in the presence of a rubbery polymer in order to produce a rubber-reinforced thermoplastic resin composition having excellent impact resistance, molding processability, and discoloration resistance. When emulsifying and polymerizing other monomer components, a method of adding a chelating agent after polymerization in the presence of a dithiocarboxylate is disclosed.

JP-A-11-246634

In the conventional method for producing a rubber graft copolymer, in order to improve the thermal stability of the obtained rubber graft copolymer, after the emulsion polymerization is completed, the latex containing the rubber graft copolymer is used as a stabilizer to prevent oxidation. The agent was added, and then a coagulation step and a drying step were carried out. However, the improvement of stability by the addition of the antioxidant was not sufficient, and there was room for improvement.

In view of the above situation, an object of the present invention is to provide a method for producing a rubber graft copolymer having excellent thermal stability by emulsion polymerization.

As a result of diligent studies to improve the thermal stability of the rubber graft copolymer, the present inventors have obtained metal ions contained in the latex, which is an emulsifying polymerization system (for example, metal ions derived from additives and polymerization equipment). It is presumed that the thermal stability of the rubber-grafted copolymer is lowered by bringing the metal ions, etc.) into the recovered rubber-grafted copolymer. As a result of diligent studies based on that speculation, when a salt is used for coagulation of the rubber graft copolymer, the rubber graft copolymer is thermally stabilized by adding a specific metal complexing agent to the latex. We have found that the sex can be improved, and have reached the present invention.

That is, the present invention is a step of graft-polymerizing a vinyl monomer component to a rubber-like polymer by emulsion polymerization to obtain a latex containing a rubber graft copolymer, and the latex is subjected to polyaminocarboxylic acid which is a metal complexing agent. A rubber graft copolymer including a step of adding a salt or phytic acid, a step of adding a salt composed of a strong acid and a strong base to the latex and coagulating it, and a step of drying the rubber graft copolymer. Regarding the manufacturing method of. Preferably, the metal complexing agent is a polyaminocarboxylate. Preferably, the amount of the metal complexing agent added to 100 parts by weight of the rubber graft copolymer is 0.005 to 5 parts by weight. Preferably, the rubber-like polymer is a polymer containing a butadiene structural unit, and the ratio of the butadiene structural unit to the rubber graft copolymer is 50% by weight or more. Preferably, the vinyl monomer component comprises methyl methacrylate and optionally another vinyl monomer, or a vinyl cyanide monomer, an aromatic vinyl monomer and optionally another vinyl. Contains monomers. Preferably, the latex further comprises the step of adding 0.1 to 10 parts by weight of the antioxidant to 100 parts by weight of the rubber graft copolymer. Preferably, the graft polymerization of the vinyl monomer component on the rubbery polymer is carried out in the absence of dithiocarbamate.
The present invention also relates to a method for producing a resin composition, which comprises a step of producing a rubber graft copolymer by the production method and a step of mixing the rubber graft copolymer with a matrix resin.

According to the present invention, it is possible to provide a method for producing a rubber graft copolymer having excellent thermal stability by emulsion polymerization. Since a rubber graft copolymer having excellent thermal stability and a high thermal decomposition start temperature is produced, it is possible to increase the heating temperature applied in the drying step of the rubber graft copolymer, and as a result, the drying efficiency is improved. be able to. It is also possible to reduce the amount of antioxidants conventionally used for thermal stability and reduce manufacturing costs.

Embodiments of the present invention will be described in detail below.

According to one embodiment of the present invention, after synthesizing a granular rubber-like polymer by emulsion polymerization, a vinyl monomer component is added and graft-polymerized on the rubber-like polymer to obtain a rubber graft co-weight. After obtaining a latex containing a coalescence, the rubber graft copolymer is coagulated by adding a coagulant to the latex, and the coagulated rubber graft copolymer is separated from water and then dried. , Obtain a powdered rubber graft copolymer.

(Rubber graft copolymer)
The rubber graft copolymer referred to in the present invention is a shell portion formed by graft-polymerizing a vinyl monomer component capable of graft copolymerization with a particulate rubber polymer serving as a core layer. Also called core-shell polymer particles. The rubber graft copolymer is formed by graft-polymerizing a core layer made of a particulate rubber-like polymer existing inside and the surface of the core layer to cover the periphery or a part of the rubber-like polymer. It has a structure having one shell layer.

(Rubber polymer)
The rubber-like polymer is not particularly limited, and examples thereof include polybutadiene, poly (butadiene-styrene), acrylic rubber, polysiloxane rubber-based elastic material, and aromatic vinyl crosslinked product. Among them, polymers containing butadiene structural units such as polybutadiene and poly (butadiene-styrene) are preferable because they are excellent in the effect of improving thermal stability according to the present invention. In this case, the proportion of the butadiene structural unit in the rubber graft copolymer is preferably 50% by weight or more and 100% by weight or less. The ratio is more preferably 70% by weight or more, further preferably 80% by weight or more, and particularly preferably 90% by weight or more.

Polybutadiene or poly (butadiene-styrene) may be one that does not contain a vinyl-based monomer other than butadiene and styrene, or may contain such a vinyl-based monomer. Examples of such vinyl-based monomers include aromatic vinyl-based monomers such as α-methylstyrene (excluding styrene); acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate, 2-acrylic acid. (Meta) acrylic acids and (meth) acrylic acid alkyl esters such as ethylhexyl, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate; unsaturateds such as acrylonitrile and methacrylate. Examples thereof include nitrile-based monomers.

Further, polybutadiene or poly (butadiene-styrene) uses a polyfunctional monomer such as divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, and 1,3-butylene methacrylate at the time of its polymerization. There may be.

Further, polybutadiene or poly (butadiene-styrene) may be polymerized without the use of a chain transfer agent, or may be polymerized in the presence of a chain transfer agent. The chain transfer agent that can be used is not particularly limited, and for example, alkyl mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, t-decyl mercaptan, n-decyl mercaptan, and n-octyl mercaptan, 2-ethylhexyl thioglycol. Examples thereof include alkyl ester mercaptans such as rates.

The acrylic monomer constituting the acrylic rubber is not particularly limited, and for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate. Acrylic acid alkyl esters such as behenyl acrylate; aromatic ring-containing acrylates such as phenoxyethyl acrylate and benzyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; glycidyl acrylate, glycidyl alkyl acrylate and the like. Glycidyl acrylate; alkoxyalkyl acrylate and the like. Of these, alkyl ester acrylate is preferable, and butyl acrylate is particularly preferable.

Further, a monomer other than the acrylic monomer may be used in combination, or may not be used in combination. Other monomers include methacrylic monomers, aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile, vinyl halides such as vinyl chloride; vinyl acetate; alkenes such as ethylene and propylene. And so on. The polymerization ratio of the acrylic monomer with respect to the entire acrylic rubber is preferably 50% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, and particularly preferably 90% by weight or more.

The acrylic rubber has a crosslinked structure. To introduce a crosslinked structure, for example, when a polymer of the core layer is synthesized by polymerizing a monomer component, a crosslinked monomer such as a polyfunctional monomer or a mercapto group-containing compound is used. Just do it.

Examples of the polyfunctional monomer include allylalkyl (meth) acrylates such as allyl (meth) acrylate and allylalkyl (meth) acrylate; allyloxyalkyl (meth) acrylates; (poly) ethylene glycol di (meth). Polyfunctional (meth) having two or more (meth) acrylic groups such as acrylate, butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. Meta) Acrylate; Examples thereof include diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. Allyl methacrylate, triallyl isocyanurate, butanediol di (meth) acrylate, and divinylbenzene are preferable, and allyl methacrylate is particularly preferable.

The total usage ratio of the polyfunctional monomer in the acrylic rubber is preferably 100 parts by weight in total of the monomer components (monomers other than the polyfunctional monomer) constituting the acrylic rubber. Is 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, still more preferably 0.1 to 3 parts by weight.

As the polysiloxane rubber-based elastic body, a polysiloxane rubber composed of an alkyl or aryl 2-substituted silyloxy unit such as dimethylsilyloxy, methylphenylsilyloxy, or diphenylsilyloxy can be used. Further, the polysiloxane rubber-based elastic body is crosslinked by, if necessary, using a part of a polyfunctional alkoxysilane compound at the time of polymerization or radically reacting a silane compound having a vinyl-reactive group. Those with an introduced structure are more preferable.

Examples of the aromatic vinyl crosslinked product include a copolymer of an aromatic vinyl compound and a crosslinkable monomer. Examples of the aromatic vinyl compound include unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; substituted vinyl aromatic compounds such as α-methylstyrene; 3-methylstyrene, 4-methylstyrene, 2,4. Ring-alkylated vinyl aromatic compounds such as −dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene; ring alkoxyls such as 4-methoxystyrene and 4-ethoxystyrene. Vinyl aromatic compounds; Ring halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; Ring ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; Rings such as 4-humanoxystyrene Examples include hydroxylated vinyl aromatic compounds.

(Vinyl monomer component)
The vinyl monomer component to be graft-polymerized on the rubber-like polymer is not particularly limited, and may be appropriately determined in consideration of the use of the produced rubber-grafted copolymer and the affinity with the matrix resin to be used in combination. it can. Specifically, it is selected from (meth) acrylic acid ester-based monomer, aromatic vinyl-based monomer, vinyl cyanide-based monomer, unsaturated carboxylic acid derivative, (meth) acrylamide derivative, and maleimide derivative. One or more of them can be mentioned.

Examples of the (meth) acrylic acid ester-based monomer include (meth) acrylics such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Acrylic acid esters can be mentioned. Examples of the aromatic vinyl-based monomer include alkyl-substituted styrenes such as styrene and α-methylstyrene, halogen-substituted styrenes such as bromostyrene and chlorostyrene, and the like. Examples of the vinyl cyanide-based monomer include (meth) acrylonitrile and substituted (meth) acrylonitrile. Examples of the unsaturated carboxylic acid derivative include (meth) acrylic acid, itaconic acid, crotonic acid, maleic anhydride and the like. Examples of the (meth) acrylamide derivative include (meth) acrylamide (including N-substituted products) and the like. Examples of the maleimide derivative include imide maleate (including N-substituted products) and the like.

Further, as the vinyl monomer component, one or more kinds of vinyl monomers having a reactive functional group selected from the group consisting of an epoxy group, a carboxyl group, a hydroxyl group, an amino group, and a carbon-carbon double bond are used. You may use it. By introducing such a reactive functional group into the shell layer of the rubber graft copolymer, the rubber graft copolymer can be made to have reactivity with the matrix resin. Examples of the monomer having a reactive functional group include 2-hydroxyethyl (meth) acrylate, 2-aminoethyl (meth) acrylate, and (meth) acrylic acid esters having a reactive side chain. Meta) Glycidyl acrylate and the like; Examples of the vinyl ether having a reactive functional group include glycidyl vinyl ether and allyl vinyl ether.

In the present invention, the vinyl monomer component graft-polymerized on the rubber-like polymer contains methyl methacrylate and optionally other vinyl monomers because it is excellent in the effect of improving the thermal stability according to the present invention. Alternatively, it preferably contains a vinyl cyanide monomer, an aromatic vinyl monomer, and optionally other vinyl monomers.

(Emulsion polymerization)
Emulsion polymerization can be carried out by a conventional method. Specifically, first, a latex of rubber-like polymer particles corresponding to the core layer is produced by emulsion polymerization, and the vinyl monomer component and polymerization are started on the latex. An agent or the like may be added to graft-polymerize the vinyl monomer component onto the rubber-like polymer particles.

The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants and the like can be used. Further, a dispersant such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivative may be used. Among the above emulsifiers, the anionic surfactant is not particularly limited, and examples thereof include the following compounds: potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium diethanolamine oleate, sodium oleate. , Sodium palmitate, potassium stearate, sodium stearate, mixed fatty acid soda soap, semi-hardened beef fat fatty acid soda soap, castor oil potassium soap and other fatty acid soaps; sodium dodecyl sulfate, higher alcohol sodium sulfate, triethanolamine dodecyl sulfate, dodecyl Alkyl sulfate esters such as ammonium sulfate, sodium polyoxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and sodium 2-ethylhexyl sulfate; alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate. Sodium acid; sodium dialkyl sulfosuccinate such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkylnaphthalene sulfonate; sodium alkyldiphenyl ether disulfonate; potassium alkyl phosphate; phosphate ester salt such as polyoxyethylene lauryl ether sodium phosphate Sodium salt of naphthalene sulfonic acid formalin condensate; polycarboxylic acid type polymer anion; sodium acyl (beef) methyl taurate; sodium acyl (palm) methyl taurate; sodium cocoyl acetylate; sodium α-sulfo fatty acid ester Sodium amide ether sulfonate; oleyl sarcosin; sodium lauroyl sarcosin; soap logate, etc.

The nonionic surfactant among the above emulsifiers is not particularly limited, and examples thereof include the following compounds: polyoxyethylene alkyls such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether. Allyl ethers or polyoxyethylene alkyl ethers, polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyethylene glucol monolaurate, polyethylene glucol monostearate, polyethylene glu Polyoxyethylene fatty acid esters such as colmonooleate, oxyethylene / oxypropylene block copolymers, etc.

Among the above emulsifiers, the cationic surfactant is not particularly limited, and examples thereof include the following compounds: alkylamine salts such as coconatamine acetate, stearylamine acetate, octadecylamine acetate, and tetradecylamine acetate; lauryltrimethyl. Tertiary ammonium salts such as ammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride, alkylbenzyldimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride and the like.

Of the above emulsifiers, the amphoteric tenside is not particularly limited, and examples thereof include the following compounds: alkyl betaines such as lauryl betaine, stearyl betaine, and dimethyl lauryl betaine; sodium lauryl diaminoethylglycine; amide betaine; imidazoline; lauryl. Carboxymethylhydroxyethyl imidazolinium betaine, etc.

These emulsifiers (dispersants) may be used alone or in combination of two or more. By adjusting the amount of the emulsifier used, the average particle size of the polymer particles can be controlled.

In emulsion polymerization, known polymerization initiators, that is, 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, ammonium persulfate and the like can be used as the thermal decomposition initiator.

In addition, organic compounds such as t-butylperoxyisopropyl carbonate, paramentanhydroperoxide, cumenehydroperoxide, dicumyl peroxide, t-butylhydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Oxides: Peroxides such as inorganic peroxides such as hydrogen peroxide, potassium persulfate, ammonium persulfate, and reducing agents such as sodium formaldehyde sulfoxylate and glucose as needed, and iron sulfate (II) as needed. ) And other transition metal salts, a chelating agent such as ethylenediaminetetraacetic acid disodium if necessary, and a phosphorus-containing compound such as sodium pyrophosphate if necessary, and a redox-type initiator can also be used.

When the redox-type initiator is used, the polymerization can be carried out even at a low temperature at which the peroxide is substantially not thermally decomposed, and the polymerization temperature can be set in a wide range, which is preferable. Of these, it is preferable to use organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide as the redox-type initiator. The amount of the initiator used, and when the redox-type initiator is used, the amount of the reducing agent, transition metal salt, chelating agent, etc. used can be used within a known range. Further, when polymerizing a monomer having two or more radically polymerizable double bonds, a known chain transfer agent can be used in a known range. Surfactants can be additionally used, but this may also be in the known range.

The solvent used in the emulsion polymerization may be any solvent that allows the emulsion polymerization to proceed stably, and for example, water or the like can be preferably used.

The temperature at the time of emulsion polymerization may be a temperature at which the emulsifier dissolves uniformly in the solvent and is not particularly limited, but is, for example, 40 to 75 ° C, preferably 45 to 70 ° C, and more preferably 49 to 65 ° C. is there.

According to the present invention, graft polymerization of a vinyl monomer component onto a rubbery polymer can be carried out in the absence of dithiocarbamate. That is, unlike Patent Document 1, the present invention can obtain the effect of improving the thermal stability of the rubber graft copolymer according to the present invention without using dithiocarbamate.

The particle size of the rubber graft copolymer obtained by emulsion polymerization can be appropriately set, and the volume average particle size of the rubber graft copolymer may be, for example, 100 nm or more and 400 nm or less. The volume average particle size of the rubber graft copolymer is a value measured by using a particle size measuring device in the state of latex of the rubber graft copolymer, as shown in the section of Examples. ..

(Metal complexing agent)
Polyaminocarboxylic acid or phytic acid, which is a metal complexing agent or a chelating agent, is added to the latex after the polymerization reaction by the above emulsion polymerization is completed. As a result, the effect of improving the thermal stability of the rubber graft copolymer can be obtained. Of these metal complexing agents, polyaminocarboxylate is preferable because it has a high effect of improving the thermal stability of the rubber graft copolymer.

When a metal copolymer is added to latex, the metal copolymer traps metal ions, which are impurities contained in the latex, so that the metal ions easily move to the aqueous phase, and the rubber graft separated from the aqueous phase is also present. It is presumed that the thermal stability of the rubber graft copolymer is improved because the introduction of metal ions into the polymer can be reduced. However, even if a condensed phosphate such as pyrophosphate or an oxycarboxylic acid salt such as citric acid, which is generally known as a metal complexing agent, is used, the effect of improving thermal stability cannot be achieved. The effects achieved by the present invention are those specific to polyaminocarboxylates or phytic acids.

The polyaminocarboxylate is a compound having two or more amino groups and one or more carboxylic acid bases in the molecule, and is not particularly limited. For example, ethylenediaminetetraacetic acid disodium salt and diethylenetriamine pentaacetic acid pentasoate. Examples thereof include salts and trisodium nitrilotriacetic acid salts.

The amount of the polyaminocarboxylate or phytic acid added is 100 parts by weight of the rubber graft copolymer from the viewpoint of the effect of improving the thermal stability of the rubber graft copolymer and the stability of the latex after the addition of the metal complexing agent. On the other hand, it is preferably 0.005 to 5 parts by weight. It is more preferably 0.01 to 4 parts by weight, and even more preferably 0.01 to 3 parts by weight.

These metal complexing agents may be added to the latex after the graft copolymerization is completed and before the graft copolymer is separated from water. That is, the metal complexing agent may be added to the latex before the coagulant described later is added to the latex, or the metal complexing agent may be added to the latex after the coagulant is added to the latex. Good. Further, a coagulant and a metal complexing agent may be added to the latex at the same time. However, it is preferable to add the metal complexing agent to the latex before adding the coagulant to the latex.

The metal complexing agent may be added as it is, or may be added in the state of an aqueous solution. In order to maintain the stability of the latex after adding the metal complexing agent, it is preferable to add the metal complexing agent in the state of an aqueous solution.

(Coagulation)
After the polymerization reaction is completed, a salt composed of a strong acid and a strong base is added as a coagulant to the latex to perform coagulation. Conventionally, it is known that an acid such as sulfuric acid, hydrochloric acid, or acetic acid is used as the coagulant, but when the coagulant is an acid, the rubber graft copolymer by adding the metal complexing agent The effect of improving thermal stability cannot be achieved. The effect of improving the thermal stability of the rubber graft copolymer by the addition of the metal complexing agent is an effect peculiar to the case where a salt is used as the coagulant.

The salt composed of a strong acid and a strong base, which is a coagulant, is not particularly limited, and known ones can be used. For example, as a cation, a group 1 element ion or a group 2 element ion and as an anion. Examples thereof include salts with Group 17 element ions, sulfate ions or nitrate ions. Specific examples thereof include calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride and the like.

The amount of the coagulant added is not particularly limited and can be appropriately set according to the particle size of the rubber graft copolymer, the type of emulsifier used, and the like. For example, 0.1 per 100 parts by weight of latex. It may be in the range of ~ 100 parts by weight.

(Antioxidant)
In the present invention, an antioxidant may be further added to the latex after emulsion polymerization. By adding an antioxidant, the effect of improving the thermal stability of the rubber graft copolymer can be further enhanced. The time at which the antioxidant is added is not particularly limited, and the graft copolymer may be added to the latex before it is separated from water.

The antioxidant is not particularly limited, and examples thereof include a phenol-based antioxidant, an amine-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant.

Examples of the phenolic antioxidant include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and octadodecyl-3- (3,5-di-tert-). Butyl-4-hydroxyphenyl) propionate, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate] and 1,3,5-tris (3,5-di) -Tert-Butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione and the like can be mentioned.

Examples of the amine-based antioxidant include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sevacate and bis (1,2,2,6,6, -pentamethyl-4-piperidyl). Examples thereof include -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate.

Examples of the phosphorus-based antioxidant include tris (2,4-di-tert-butylphenyl) phosphite, distearylpentaerythritol diphosphite and the like.

Examples of the sulfur antioxidant include dioctadecyl 3,3-thiodipropionate, didodecyl 3,3-thiodipropionate and the like.

The amount of the antioxidant added can be appropriately set, but for example, it is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the rubber graft copolymer. , 0.5 to 3 parts by weight is more preferable.

(Dry)
After coagulating the rubber graft copolymer, the rubber graft copolymer can be separated from water, washed if necessary, and then dried to obtain a powdery rubber graft copolymer. it can. When the rubber graft copolymer is separated from water, centrifugation, filtration or the like may be used. In addition, water and / or an organic solvent can be appropriately used for the cleaning. Heat drying, spray drying and the like can be applied to the drying. Since the rubber graft copolymer obtained by the present invention has excellent thermal stability, a relatively high temperature can be adopted as the temperature during heat drying.

(Rubber graft copolymer)
The rubber graft copolymer obtained by the present invention can be used alone as a molding material, but it is blended as a resin modifier in a matrix resin in order to improve physical properties such as impact resistance of the matrix resin, for example. It is also possible to construct a resin composition.

The matrix resin is not particularly limited, and examples thereof include a thermosetting resin such as an epoxy resin and a thermoplastic resin. Examples of the thermoplastic resin include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, polyacetal, polycarbonate, modified polyphenylene ether, and polyethylene terephthalate. Examples thereof include polybutylene terephthalate and cyclic polyolefin.

The blending amount with respect to the matrix resin can be appropriately set according to the desired physical properties. For example, the ratio of the rubber graft copolymer to the total of the rubber graft copolymer and the matrix resin is 1 to 40% by weight. Is preferable, and 3 to 30% by weight is more preferable.

The resin composition can appropriately contain additives that can be blended with general resin compositions. Such additives are not particularly limited, but for example, flame retardants, flame retardants, dripping inhibitors, reinforcing materials, fillers, antioxidants, pigments, dyes, conductivity-imparting agents, hydrolysis inhibitors, etc. Examples thereof include thickeners, plasticizers, lubricants, ultraviolet absorbers, antistatic agents, fluidity improvers, mold release agents, compatibilizers, heat stabilizers and the like.

The method for producing the resin composition of the present invention is not particularly limited, and a general method for producing a resin composition can be applied. For example, after mixing each raw material using a Henschel mixer, a tumbler mixer, or the like, melt kneading can be performed to obtain a resin composition. For the melt kneading, a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll can be used. By such melt kneading, pellets made of a resin composition can be produced.

The resin composition of the present invention can be molded into a predetermined shape to obtain a molded product. The molding method is not particularly limited, and for example, an injection molding method, an extrusion molding method, a blow molding method, a calendar molding method, an inflation molding method, a rotary molding method, a press molding method and the like can be used.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In the following, unless otherwise specified, "part" means "part by weight" and "%" means "% by weight".

[PH measurement under polymerization conditions]
A part of the latex being polymerized was collected and the pH was measured. The pH was measured with a pH meter (D-21 HORIBA).

[Polymerization conversion rate]
A part of the obtained latex was collected and precisely weighed, dried in a hot air dryer at 120 ° C. for 1 hour, and the weight after drying was precisely weighed as the solid content. Next, the ratio of the precision results before and after drying was determined as the ratio of solid components in latex. Finally, using this solid component ratio, the polymerization conversion rate was calculated by the following formula.
Formula: Polymerization conversion rate = (total weight of charged raw materials x solid component ratio-total weight of raw materials other than monomer) / weight of charged monomer x 100 (%)

[Volume average particle size]
The volume average particle size of the rubber-like polymer and the volume average particle size of the rubber graft copolymer were measured in the state of latex. As a measuring device, MICROTRAC UPA150 manufactured by Nikkiso Co., Ltd. was used.

[Pyrolysis start temperature]
The thermal decomposition start temperature of the rubber graft copolymer was measured by differential thermal analysis DTA. Using the thermal analysis station TAS-100 manufactured by Rigaku Denki Co., Ltd., measurement was performed at a temperature rise rate of 10 ° C./min under an air flow of 65 ml / min, and α-alumina was used as the standard sample. 5 mg of each measurement sample was used. In the obtained chart, the intersection of the baseline and the maximum slope of the peak was defined as the thermal decomposition start temperature (° C.).

[Example 1] Synthesis of rubber graft copolymer (Example 1a) Production of rubber-like polymer In a pressure-resistant container with a stirrer
180 parts of pure water,
0.002 parts of ethylenediaminetetraacetic acid disodium salt (EDTA),
0.0012 parts of ferrous sulfate,
Polyoxyethylene alkyl ether sodium phosphate 0.08 parts,
After preparing and deoxidizing
100 parts of butadiene,
Sodium formaldehyde sulfoxylate 0.05 part,
Paramentan hydroperoxide 0.03 part,
Was added, and then 1.4 parts of polyoxyethylene alkyl ether sodium phosphate was added dropwise over 6 hours, followed by holding at 50 ° C. for 15 hours at pH 6.5 to 7.5 of the reaction solution, and a conversion rate of 98% by weight. A diene-based rubber latex (1a) having a volume average particle diameter of 150 nm was obtained.

(Example 1b) Production of rubber graft copolymer by forming a graft layer Methyl as a monomer while maintaining the diene-based rubber latex (1a) (solid content of about 71 parts) obtained above at 60 ° C. Methyl acid 22 parts,
7 parts of styrene,
Was added over 1 hour. At the same time as the addition of the above monomer
0.07 parts of t-butyl hydroperoxide,
Sodium formaldehyde sulfoxylate 0.1 part,
Was started, and then the whole amount was added over 2 hours while keeping the pH of the reaction solution at 6.5-7.5 and the temperature at about 60 ° C. Further, the reaction solution was held at about 60 ° C. for 1 hour, and after the polymerization was completed, 0.005 part of ethylenediaminetetraacetic acid disodium salt was added as a metal complexing agent, and a rubber graft copolymer latex having a volume average particle diameter of 170 nm was added. (1b) was obtained.

IRGANOX245 [triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], which is a phenolic antioxidant, is added to this rubber graft copolymer latex (1b). After adding 3 parts and 1.3 parts of Yoshitomi [dilaurylthiozopropionate], which is a thioether-based antioxidant, an aqueous solution of calcium chloride is further added for coagulation, washing with water, dehydration, and drying. A powdery rubber graft copolymer (1c) was obtained.

[Example 2] Synthesis of rubber graft copolymer Same as in Example 1 except that the amount of ethylenediaminetetraacetic acid disodium salt added after the completion of polymerization was changed to 0.02 part in the production of the rubber graft copolymer. A powdery rubber graft copolymer (2c) was obtained.

[Example 3] Synthesis of rubber graft copolymer Same as in Example 1 except that the amount of ethylenediaminetetraacetic acid disodium salt added after the completion of polymerization was changed to 0.2 part in the production of the rubber graft copolymer. A powdery rubber graft copolymer (3c) was obtained.

[Example 4] Synthesis of rubber graft copolymer The same as in Example 1 except that the amount of ethylenediaminetetraacetic acid disodium salt added after the completion of polymerization was changed to 1 part in the production of the rubber graft copolymer. A powdery rubber graft copolymer (4c) was obtained.

[Example 5] Synthesis of rubber graft copolymer During the production of the rubber graft copolymer, 0.02 part of phytic acid was added as a metal complexing agent instead of ethylenediaminetetraacetic acid disodium salt after completion of the polymerization. A powdery rubber graft copolymer (5c) was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 1] Synthesis of rubber graft copolymer Powdered rubber in the same manner as in Example 1 except that ethylenediaminetetraacetic acid disodium salt was not added after the completion of polymerization in the production of the rubber graft copolymer. A graft copolymer (6c) was obtained.

[Comparative Example 2] Synthesis of rubber graft copolymer When producing a rubber graft copolymer, instead of ethylenediaminetetraacetic acid disodium salt after the completion of polymerization,
A powdery rubber graft copolymer (7c) was obtained in the same manner as in Example 1 except that 0.02 part of pyrophosphoric acid was added.

[Comparative Example 3] Synthesis of rubber graft copolymer When producing a rubber graft copolymer, instead of ethylenediaminetetraacetic acid disodium salt after the completion of polymerization,
A powdery rubber graft copolymer (8c) was obtained in the same manner as in Example 1 except that 0.02 part of citric acid was added.

[Reference Example 1] Synthesis of rubber graft copolymer (Reference Example 1a) Production of rubber-like polymer In a pressure-resistant container with a stirrer
244 parts of pure water,
Ethylenediaminetetraacetic acid disodium salt 0.002 part,
0.001 part of ferrous sulfate,
Tripotassium Phosphate 0.5 parts,
Potassium rosinate 2 parts,
After preparing and deoxidizing
100 parts of butadiene,
Sodium formaldehyde sulfoxylate 0.02 part,
Paramentan hydroperoxide 0.06 part,
Was added, and then 0.6 part of semi-cured beef tallow fatty acid potassium was added dropwise over 5 hours, followed by holding at 50 ° C. for 8 hours at a pH of 12.5 or less of the reaction solution, a conversion of 98% by weight, and a volume average particle size. An 80 nm diene rubber latex (9a) was obtained.

(Reference Example 1b) Production of rubber graft copolymer by forming a graft layer Volume average in the same manner as in Example 1 except that the diene-based rubber latex (9a) (solid content of about 71 parts) obtained above was used. A rubber graft copolymer latex (9b) having a particle size of 100 nm was obtained.

To this rubber graft copolymer latex (9b), IRGANOX245, which is a phenolic antioxidant [triethylene glycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate] 0. Same as in Example 1 except that 7 parts and 0.7 parts of Yoshitomi [dilaurylthiozopropionate], which is a thioether-based antioxidant, were added, and then hydrochloric acid was further added for coagulation. Obtained a powdery rubber graft copolymer (9c).

[Reference Example 2] Synthesis of rubber graft copolymer In the production of the rubber graft copolymer, 0.02 part of ethylenediaminetetraacetic acid disodium salt was added as a metal complexing agent after the completion of the polymerization. In the same manner, a powdery rubber graft copolymer (10c) was obtained.

As is clear from Table 1, ethylenediaminetetraacetic acid disodium salt or phytic acid, which is a polyaminocarboxylate, is added to the latex after the completion of emulsion polymerization as a metal complexing agent, and a salt consisting of a strong acid and a strong base. In Examples 1 to 5 in which the above-mentioned metal oxidizing agent was not added, the obtained rubber graft copolymer had a higher thermal decomposition start temperature and was heated, as compared with Comparative Example 1 in which the metal oxidizing agent was not added. It can be seen that it is excellent in stability. Further, in Comparative Examples 2 and 3 in which pyrophosphate or citric acid was added as the metal complexing agent, the thermal decomposition start temperature of the rubber graft copolymer was the same as that in Comparative Example 1, and the effect of improving the thermal stability was observed. There wasn't.

Further, in Reference Examples 1 and 2, an acid was used as the coagulant instead of a salt composed of a strong acid and a strong base, but Reference Example 2 to which the same metal copolymer as in Examples 1 to 4 was added. Then, the thermal decomposition start temperature of the rubber graft copolymer was the same as that of Reference Example 1 in which the metal complexing agent was not added. From this, it can be seen that the effect of improving the thermal stability achieved by adding the metal complexing agent is an effect peculiar to the case where a salt composed of a strong acid and a strong base is used as the coagulant.

Claims (8)

A step of graft-polymerizing a vinyl monomer component to a rubber-like polymer by emulsion polymerization to obtain a latex containing a rubber graft copolymer.
A step of adding a metal complexing agent, polyaminocarboxylic acid or phytic acid, to the latex.
A step of adding a salt consisting of a strong acid and a strong base to the latex to coagulate it, and
A method for producing a rubber graft copolymer, which comprises a step of drying the rubber graft copolymer. The method for producing a rubber graft copolymer according to claim 1, wherein the metal complexing agent is a polyaminocarboxylic acid salt. The method for producing a rubber graft copolymer according to claim 2, wherein the amount of the metal complexing agent added to 100 parts by weight of the rubber graft copolymer is 0.005 to 5 parts by weight. The rubber-like polymer is a polymer containing a butadiene structural unit.
The method for producing a rubber graft copolymer according to any one of claims 1 to 3, wherein the butadiene structural unit accounts for 50% by weight or more of the rubber graft copolymer. The vinyl monomer component contains methyl methacrylate and optionally another vinyl monomer, or a vinyl cyanide monomer, an aromatic vinyl monomer, and optionally another vinyl monomer. The method for producing a rubber graft copolymer according to any one of claims 1 to 4, which comprises. The rubber graft according to any one of claims 1 to 5, further comprising a step of adding 0.1 to 10 parts by weight of an antioxidant to 100 parts by weight of the rubber graft copolymer to the latex. Method for producing a polymer. The method for producing a rubber-grafted copolymer according to any one of claims 1 to 6, wherein the graft polymerization of the vinyl monomer component on the rubber-like polymer is carried out in the absence of dithiocarbamate. A resin composition comprising a step of producing a rubber graft copolymer by the production method according to any one of claims 1 to 7 and a step of mixing the rubber graft copolymer with a matrix resin. Production method.