JPH11292940A - Polymer particle of multilayerd structure, its production and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polymer particles that can give molded products having excellent elastic recovery (low permanent deformation) by constituting the particles with specific two or more layers and specifying their average particle size. SOLUTION: The polymer particle has at least one rubber component layer (A) in the inner part and at least one thermoplastic resin component layer (B) at least on the outermost layer. The component layer A is constituted with a layer of a copolymer obtained from 50-99.99 wt.% of an acrylic ester and 49.99-0 wt.% of other functional monomer copolymerizable with the acrylic ester and 0.01-0 wt.% of a polyfunctional monomer, while the component layer B comprises a layer of a copolymer obtained from 40-99 wt.% of a methacrylic ester and 60-1 wt.% of other monomer copolymerizable with the methacrylic ester. The component layer B on the outermost layer has a number-average molecular weight of <=30,000 (according to the GPC) and the whole weight ratio of the component A to the component B is 30/70-90/10, and the average particle size is adjusted to 150 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer particle having a multilayer structure, and more particularly to a method for producing the polymer particle having a multilayer structure and its use. More specifically, the present invention relates to a resin layer (II) containing at least one rubber component layer (I) inside and at least the outermost layer having thermoplasticity.
Is a multi-layered polymer particle that contains not only excellent flexibility but also elastic recovery properties (low permanent set properties) by reducing the molecular weight of the outermost resin layer (II) to a specific value or less. The present invention relates to a novel polymer having a multilayer structure and a method for producing the same, and a molding material and a molded article comprising the polymer particle having a multilayer structure. The present invention further relates to a resin composition comprising the multilayer polymer particles and a synthetic resin, a molding material and a molded article comprising the resin composition.

[0002]

2. Description of the Related Art Multilayer polymer particles are also referred to as core-shell type polymers and contain a layer made of a rubber component inside and a layer made of a thermoplastic resin component outside. It is used for modifying thermoplastic resins such as polyvinyl chloride, polyester, and acrylic resin. Among them, it is known that it is useful as a modifier for imparting toughness.

In order to improve the melt-kneading properties with other thermoplastic resins, multilayer polymer particles are used.
The number average molecular weight of the thermoplastic resin component constituting the outermost layer of the multilayer structure particles is usually controlled to about 35,000 to 50,000, and for controlling the molecular weight, polymerization for forming the outermost layer is performed. In the reaction step, a molecular weight regulator such as an alkyl mercaptan is not used at all, or even if it is used, the amount of the molecular weight regulator is 0.1 to the monomer.
It is common to limit the amount to less than 3% by weight.

[0004]

However, a molded article comprising a multilayered polymer particle or a resin composition of the same and a synthetic resin lacks elastic recovery (that is, low permanent set characteristics), and the improvement is not achieved. Is desired.

[0005] An object of the present invention is to provide a novel molded article having excellent elastic recovery properties (low permanent set characteristics) when the molded article itself or a resin composition of the resin and the synthetic resin is used. An object of the present invention is to provide multilayer polymer particles. Another object of the present invention is to provide a method for producing the novel multilayer polymer particles. Another object of the present invention is to provide a molding application of the novel multilayer polymer particles. Still another object of the present invention is to provide a resin composition using the novel multilayer polymer particles and a molding use of the resin composition.

[0006]

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above problems, and have found that the molecular weight of the thermoplastic resin component constituting the outermost layer of the multilayer polymer particles and the average molecular weight of the particles are as follows. It has been found that when the particle diameter is controlled to a specific range, excellent elastic recovery is exhibited, and as a result of further studies, the present invention has been completed.

According to the present invention, one of the above objects is to:

(1) A multilayer comprising at least one of the following rubber component layers (I) inside and at least one of the following thermoplastic resin component layers (II) at least outermost, comprising two or more layers Structural polymer particles;

(2) The rubber component layer (I) comprises 50 to 99.99% by weight of an acrylate ester, 49.99 to 0% by weight of another monofunctional monomer copolymerizable with the acrylate ester, A polymer layer formed by copolymerization of a monomer mixture (i) consisting of 0.01 to 10% by weight of a polyfunctional monomer;

(3) The thermoplastic resin component layer (II) is a monomer mixture comprising 40 to 99% by weight of a methacrylic acid ester and 60 to 1% by weight of another monomer copolymerizable with the methacrylic acid ester. (Ii) a polymer layer formed by copolymerization;

(4) The number average molecular weight of the polymer constituting the outermost layer of the thermoplastic resin component layer (II) measured by the GPC method is 300,000,000 or less;

(5) The ratio of the total weight of the rubber component layer (I) to the total weight of the thermoplastic resin component layer (II) is 30/70 to 90/10 in the layer (I) / layer (II). Within the range;

(6) the average particle size is 150 nm or less;

This is achieved by providing multilayer polymer particles characterized by the following characteristics (hereinafter, such multilayer polymer particles are sometimes referred to as “multilayer polymer particles (A)”).

According to the present invention, one of the above objects is to:

(1) The polymerization reaction step (a) for forming the rubber component layer (I) and the polymerization reaction step (b) for forming the thermoplastic resin component layer (II) are performed in a predetermined order. Thereby, at least one rubber component layer (I) is formed inside, and at least one thermoplastic resin component layer (II) is formed at least as an outermost layer. A method for producing a multi-layer polymer particle comprising two or more layers, the method comprising:

(2) In the polymerization reaction step (a), 50 to 99.99% by weight of an acrylate ester and 49.9 of another monofunctional monomer copolymerizable with the acrylate ester
9 to 0% by weight and 0.01 to 10% by weight of a polyfunctional monomer
Copolymerizing a monomer mixture (i) consisting of:

(3) In the polymerization reaction step (b), a monomer mixture comprising 40 to 99% by weight of a methacrylate and 60 to 1% by weight of another monomer copolymerizable with the methacrylate ( ii) is copolymerized;

(4) In the polymerization reaction step (b), at least in the polymerization reaction step for forming the outermost thermoplastic resin component layer (II), a molecular weight modifier is added to the monomer mixture (ii). To carry out a polymerization reaction using a ratio within the range of 0.4 to 10% by weight with respect to

(5) The ratio of the total weight of the monomer mixture (i) to the total weight of the monomer mixture (ii) used in the whole polymerization reaction step is calculated by dividing the ratio of monomer mixture (i) / monomer In the range of 30/70 to 90/10 in mixture (ii);

(6) The average particle diameter of the multilayer polymer particles at the time when all the polymerization reaction steps are completed is 150 nm.
The following;

The present invention is attained by providing a method for producing a multilayer structured polymer particle.

According to the present invention, one of the above-mentioned objects is to provide a multilayered polymer particle (hereinafter referred to as a “multilayered polymer particle (A ′)”) obtained by the above production method. , Which may be referred to as the

According to the present invention, one of the above-mentioned objects is to provide a molding material comprising the above-mentioned multilayer polymer particles (A) or (A ′); and the above-mentioned multilayer polymer particles (A) or (A). This is achieved by providing a film or sheet comprising (A ′), respectively.

According to the present invention, one of the above-mentioned objects is achieved by providing a resin composition comprising the above-mentioned multilayer polymer particles (A) or (A ') and a synthetic resin.

According to the present invention, one of the objects is achieved by providing a molding material comprising the above resin composition; and a film or sheet comprising the above resin composition. .

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In addition, since the multilayer polymer particles (A) of the present invention can be produced by the above-mentioned production method, they often overlap the multilayer polymer particles (A ′). Therefore, the multilayer polymer particles of the present invention described below are generically referred to as the multilayer polymer particles (A) and (A ') unless otherwise specified.

The multilayer polymer particles of the present invention have at least one rubber component layer (I) inside and at least a thermoplastic resin component layer (II) as the outermost layer. The number of layers constituting the multilayer polymer particles of the present invention may be two or more, and may be three or four or more. In the case of a two-layer structure, the structure is layer (I) (center layer) / layer (II) (outermost layer), and in the case of a three-layer structure, layer (I) (innermost layer) / layer (I) ( (Intermediate layer) / layer (II) (outermost layer), layer (I) (innermost layer) / layer (II) (intermediate layer) / layer (II) (outermost layer) or layer (II) (innermost layer) /
It has a structure of layer (I) (intermediate layer) / layer (II) (outermost layer). In the case of a four-layer structure, for example, layer (I) (innermost layer)
/ Layer (II) (intermediate layer) / layer (I) (intermediate layer) / layer (II)
(Outermost layer). Among these, the layer (I) (center layer) is excellent in handleability.
/ Layer (II) (outermost layer); or layer (I) (innermost layer) / layer (I) (intermediate layer) / layer (II) (outermost layer) or layer (II) (innermost layer) / Layer (I) (intermediate layer) / layer (II)
A three-layer structure (outermost layer) is preferable.

The total weight ratio of the layer (I) to the layer (II) is as follows:
(I) / (II) falls within the range of 30/70 to 90/10. When the proportion of the layer (I) is smaller than this range, the elastic recovery in the molded article obtained by molding the multilayered polymer particles alone or a resin composition of the same and the synthetic resin becomes insufficient, and conversely, the layer (I) When the ratio is larger than this range, it is difficult to form the layer structure in a perfect form, and the melt fluidity is extremely reduced, so that molding and kneading with another synthetic resin become difficult. In addition, the total weight of the layer (I) is the weight of the layer (I) in the multilayer structure polymer particle when there is only one layer, and when the layer (I) is two or more layers, It is the sum of the weights of those layers. Similarly, the total weight of layer (II) is
When only one layer (II) is present in the multilayer polymer particles, the weight is the weight of the layer, and when there are two or more layers (II), the weight is the sum of the weights of those layers.

The layer (I) in the multi-layer polymer particles of the present invention comprises 50 to 99.99% by weight of an acrylate ester and 49.99 to another monofunctional monomer copolymerizable with the acrylate ester. 0% by weight and polyfunctional monomer 0.0
It is a polymer layer having rubber elasticity formed by copolymerization of a monomer mixture (i) consisting of 1 to 10% by weight.

Specific examples of the acrylate used to form the layer (I) include methyl acrylate, ethyl acrylate, n-propyl acrylate,
Isopropyl acrylate, n-butyl acrylate,
Isobutyl acrylate, s-butyl acrylate, t
Alkyl acrylates such as butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate and octadecyl acrylate; esters of acrylic acid and phenols such as phenyl acrylate; benzyl acrylate and the like Examples include esters of acrylic acid and aromatic alcohols. The acrylic ester is formed in the layer (I)
(When the multilayered polymer particles have two or more layers (I), each of the layers (I)) has a weight of 50 to 99.99 relative to the monomer mixture (i) used for forming the layers. %
Are used alone or in combination of two or more. If the amount of the acrylate is less than 50% by weight, the rubber elasticity of the multilayer polymer particles will decrease,
On the other hand, if the content exceeds 99.99% by weight, the structure of the multilayer polymer particles is not formed, so that both are not preferred.

The polyfunctional monomer used for forming the layer (I) is a monomer having two or more carbon-carbon double bonds in the molecule, for example, acrylic acid, methacrylic acid, Unsaturated carboxylic acids such as cinnamic acid and allyl alcohol,
Esters with unsaturated alcohols such as methallyl alcohol or glycols such as ethylene glycol and butanediol; esters of dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and maleic acid with the above unsaturated alcohols; Specifically, allyl acrylate, methallyl acrylate, allyl methacrylate, methallyl methacrylate, allyl cinnamate, methallyl cinnamate, diallyl maleate, diallyl phthalate, diallyl terephthalate,
Examples include diallyl isophthalate, divinylbenzene, ethylene di (meth) acrylate, butanediol di (meth) acrylate, and hexanediol di (meth) acrylate. Among these polyfunctional monomers, allyl methacrylate is particularly preferred. In addition, the above-mentioned “di (meth) acrylate” is a general term for “diacrylate” and “dimethacrylate”. Multifunctional monomers are
For the monomer mixture (i) used to form the layer (I) (when the multilayered polymer particles have two or more layers (I), each layer (I)), the amount of the monomer mixture (i) is set at 0. 01-10
In the range of weight%, they are used alone or in combination of two or more. When the amount of the polyfunctional monomer is more than 10% by weight, the multilayer polymer particles do not exhibit rubber elasticity, and the elastic recovery becomes insufficient, which is not preferable. When the amount of the polyfunctional monomer is less than 0.01% by weight, the layer (I) is not formed as a particle structure, which is not preferable.

In order to form the layer (I), other monofunctional monomers copolymerizable with the acrylate ester can be used in addition to the acrylate ester and the polyfunctional monomer. Examples of the other monofunctional monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate. , Dodecyl methacrylate,
Methacrylic acid alkyl esters such as myristyl methacrylate, palmityl methacrylate, stearyl methacrylate, behenyl methacrylate, and octadecyl methacrylate; esters of methacrylic acid such as phenyl methacrylate with phenols; esters of methacrylic acid such as benzyl methacrylate and aromatic alcohols; Methacrylic acid esters are typical, but in addition,
Styrene, α-methylstyrene, 1-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4-
Cyclohexylstyrene, 4-dodecylstyrene, 2-
Aromatic vinyl monomers such as ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene and halogenated styrene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; butadiene, isoprene, 2,
3-dimethylbutadiene, 2-methyl-3-ethylbutadiene, 1,3-pentadiene, 3-methyl-1,3-
Pentadiene, 2-ethyl-1,3-pentadiene,
1,3-hexadiene, 2-methyl-1,3-hexadiene, 3,4-dimethyl-1,3-hexadiene, 1,
Examples include conjugated diene monomers such as 3-heptadiene, 3-methyl-1,3-heptadiene, 1,3-octadiene, cyclopentadiene, chloroprene, and myrcene. These monomers are used, if necessary, to form the layer (I) (when the multilayered polymer particles have two or more layers (I), each layer (I)). They may be used alone or in combination of two or more at a ratio of 49.99% by weight or less based on the monomer mixture (i). The ratio of the above other monofunctional monomer is 49.9.
If it exceeds 9% by weight, the weather resistance of the multilayer polymer particles becomes insufficient, which is not preferred.

The layer (II) in the multilayered polymer particles of the present invention comprises a monomer mixture (ii) consisting of 40 to 99% by weight of a methacrylate ester and 60 to 1% by weight of another monomer copolymerizable therewith. ) Is a polymer layer having thermoplasticity formed by copolymerization. When the amount of the methacrylate is less than 40% by weight, the weather resistance of the multilayer polymer particles becomes insufficient, and when it is more than 99% by weight, the heat resistance becomes insufficient.

Specific examples of the methacrylate used to form the layer (II) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, and hexyl methacrylate. Octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, myristyl methacrylate, palmityl methacrylate, stearyl methacrylate, behenyl methacrylate, octadecyl methacrylate, phenyl methacrylate,
Benzyl methacrylate and the like are preferable, and methyl methacrylate is preferable.

Specific examples of other copolymerizable monomers used for forming the layer (II) include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and isobutyl acrylate. , S-butyl acrylate, t-butyl acrylate, pentyl acrylate,
Acrylic alkyl esters such as hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, and octadecyl acrylate; styrene, α-methylstyrene, 1-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4- Aromatic vinyl monomers such as cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene and halogenated styrene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile Monomer;
Maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide,
Maleimide monomers such as N- (chlorophenyl) maleimide; and the polyfunctional monomers shown in the above examples.
Among these, alkyl acrylates such as methyl acrylate, ethyl acrylate and n-butyl acrylate are preferred.

The layer (I) is composed of a polymer component having rubber elasticity, and the layer (II) is composed of a polymer component having thermoplasticity. The condition may be appropriately selected within the range described above.

In the multilayer polymer particles (A) of the present invention, among the layers (II) contained therein, at least the number average molecular weight of the copolymer constituting the outermost layer of the particles is GPC.
It is important that the molecular weight is not more than 30,000 based on the measurement by the (gel permeation chromatography) method. When the number average molecular weight is more than 30,000, the elastic recovery property of the molded article obtained by molding the resin composition of the multilayered polymer particles alone or the synthetic resin and the resin composition becomes insufficient, and the melt fluidity further decreases. In some cases. There is no strict limit on the lower limit of the number average molecular weight,
From the viewpoint of the passability of the production process, the number average molecular weight is 1,000
It is preferred that it does not fall below zero. From the viewpoint of compatibility between elastic recovery and production process passability, the number average molecular weight is 3,000.
It is particularly preferred to be within the range of 0 to 20,000.

The average particle size of the multilayer polymer particles of the present invention is 150 nm or less. If it is larger than 150 nm, the elastic recovery becomes insufficient. In some cases, the melt fluidity is not good. The lower limit of the average particle diameter is not particularly limited, but from the viewpoint of easily forming a predetermined layer structure of the multilayer polymer particles, the average particle diameter is 30 nm.
It is preferable that it is above.

The polymer particles having a multilayer structure according to the present invention can be obtained by carrying out a polymerization reaction step for forming a rubber component layer and a polymerization reaction step for forming a thermoplastic resin component layer in a predetermined order, so that the central part thereof is formed. A multilayer comprising at least one rubber component layer inside and at least one thermoplastic resin component layer at least outermost, comprising a layer formed sequentially from It can be produced according to a known production method for producing structural polymer particles. However, it is necessary to pay attention to the following points.

(1) In the polymerization reaction step (a) for forming the rubber component layer (I), the acrylate 5
0 to 99.99% by weight, 49.99 to 0% by weight of another monofunctional monomer copolymerizable with the acrylic acid ester and 0.01 to 10% by weight of a polyfunctional monomer Copolymerizing the body mixture (i).

(2) In the polymerization reaction step (b) for forming the thermoplastic resin component layer (II), 40 to 99% by weight of a methacrylic acid ester and another monomer copolymerizable with the methacrylic acid ester Copolymerizing a monomer mixture (ii) consisting of 60 to 1% by weight.

(3) In the polymerization reaction step (b), at least in the polymerization reaction step for forming the outermost thermoplastic resin component layer (II), a molecular weight modifier is added to the monomer mixture (ii) To carry out the polymerization reaction at a ratio within the range of 0.4 to 10% by weight.

(4) The ratio of the total weight of the monomer mixture (i) to the total weight of the monomer mixture (ii) used in the entire polymerization reaction step is calculated by dividing the ratio of monomer mixture (i) / monomer In the mixture (ii), it should be in the range of 30/70 to 90/10.

(5) The average particle diameter of the multilayer polymer particles at the time when all the polymerization reaction steps are completed is 150 nm.
Control so that:

The above polymerization method is not particularly limited.
For example, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a solution polymerization method, or a combination thereof can be employed according to a known polymerization method for producing ordinary multilayer polymer particles.

For example, in emulsion polymerization, according to known means,
By performing polymerization for forming each layer, the multilayer polymer particles of the present invention can be obtained. The temperature of the emulsion polymerization is not necessarily limited, but a general range is from 0 to 100C. As the emulsifier used here,
Aliphatic alkali metal salts such as sodium oleate, sodium laurate and sodium stearate; sulfates of aliphatic alcohols such as sodium lauryl sulfate; rosinates such as potassium rosinate; alkyls such as dodecylbenzenesulfonic acid Allylsulfonic acid and the like can be mentioned, and these are used in combination of one or more kinds. As the polymerization initiator used in the emulsion polymerization, a radical polymerization initiator is generally used. As specific examples of the radical polymerization initiator, peroxides such as persulfate, azobisisobutyronitrile, and benzoyl peroxide can be used alone. In addition, as a radical polymerization initiator, a redox initiator obtained by combining an organic hydroperoxide such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, or paramenthane hydroperoxide with a reducing agent such as a transition metal salt is used. can do.

As described above, a predetermined amount of a predetermined monomer mixture is sequentially polymerized in accordance with a known emulsion polymerization method, whereby a predetermined polymer layer is formed stepwise from the center of the particle toward the outside. However, in order to produce the multilayer polymer particles of the present invention, in the polymerization reaction step for forming at least the outermost layer, a molecular weight modifier is used in the monomer mixture (ii) used in the step. It is particularly important to use a proportion in the range of 0.4 to 10% by weight with respect to When producing ordinary multi-layer polymer particles, the amount of the molecular weight regulator used in the polymerization reaction for forming the outermost thermoplastic resin component layer is generally from 0 to 0. Although it is about 3% by weight, when the amount is less than 0.4% by weight, the number average molecular weight of the thermoplastic resin component constituting the layer becomes too high, and the multilayer structure polymer particles or the synthetic resin and the multilayer structure polymer particles are mixed. In some cases, the molded article obtained by molding the resin composition of the above may have insufficient elastic recovery and may have insufficient molding fluidity. For the purpose of the present invention, it is sufficient if the amount of the molecular weight regulator is at most 10% by weight based on the above-mentioned standard, and if it is used in excess, there is no longer any further improvement in the effect of imparting elastic recovery. The residual amount of the molecular weight regulator in the multilayer polymer particles is undesirably increased.

Specific examples of the molecular weight regulator include mercaptans such as n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol; terpinolene, dipentene, t-terpinene and a small amount of A terpene mixture of cyclic terpenes; halogenated hydrocarbons such as chloroform and carbon tetrachloride. Of these, alkyl mercaptans such as n-octyl mercaptan are preferred.

Since the average particle size of the multilayer polymer particles obtained by emulsion polymerization is affected by polymerization conditions such as the amount of the emulsifier, the final multilayer structure weight can be easily determined by appropriately selecting these conditions. The average particle diameter of the coalesced particles can be controlled to 150 nm or less.

After the emulsion polymerization, the resulting multi-layered polymer particles can be separated and obtained from the polymerization reaction system according to a known method, for example, an acid precipitation method, a salt precipitation method, a spray drying method, and a freeze coagulation method. Etc. can be adopted. In addition,
The multilayer-structured polymer particles obtained by separation may be partially fused to each other in the outermost layer made of a thermoplastic resin component.

The multilayer polymer particles of the present invention can be subjected to thermal molding because the outermost layer has thermoplasticity and is excellent in melt fluidity.
By molding methods such as extrusion molding at 0 ° C, injection molding, hollow molding, calendar molding, compression molding, vacuum molding, foam molding, etc.
It can be formed into a molded article of any shape such as powder, pellet, plate, film or sheet, pipe, hollow, box and the like. Since the molded article has excellent elastic recovery properties, it is suitably used for applications such as soft members for automobile interiors, packaging films, desk mats and the like.

In the multilayer polymer particles of the present invention, since the outermost layer has thermoplasticity, it is possible to form a resin composition of the multilayer polymer particles and a synthetic resin.

In the resin composition comprising the multi-layered polymer particles of the present invention and another synthetic resin, the content of the multi-layered polymer particles is 5% by weight or more in order to exhibit excellent elastic recovery performance. Preferably, the content of the synthetic resin is 95% by weight or less. However, if the content of the multilayer polymer particles is too high, the original properties of the synthetic resin tend to be lost.Therefore, in order to achieve both the elastic recovery property and the original properties of the synthetic resin, the multilayer polymer particles are required. And the weight ratio of the synthetic resin and the synthetic resin is preferably in the range of 25/75 to 75/25.

In the resin composition comprising the polymer particles having a multilayer structure of the present invention and another synthetic resin, the synthetic resin is not particularly limited, and any of a thermoplastic resin and a thermosetting resin may be used. Can be. Specific examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene ionomers; polystyrene, styrene-maleic anhydride copolymer, Impact polystyrene, ABS, AES, A
Styrene resins such as AS, ACS and MBS; Acrylic resins such as polymethyl methacrylate, methyl methacrylate-styrene copolymer, other acrylic multi-layer polymer particles; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Nylon 6 , Nylon 66, polyamides such as polyamide elastomers; polycarbonate; polyvinyl chloride; polyvinylidene chloride; polyvinyl alcohol; ethylene-vinyl alcohol copolymer; polyacetal;
Polyurethane; modified polyphenylene ether; polyphenylene sulfide; silicone rubber-modified resin. Specific examples of the thermosetting resin include an epoxy resin, an unsaturated polyester, a phenol resin, a urea resin, and a melamine resin.

The resin composition comprising the polymer particles having a multilayer structure of the present invention and a synthetic resin may contain various known additives (for example, rubber, lubricant, antioxidant, plasticizer) as long as the effects of the present invention are not impaired. Agents, light stabilizers, coloring agents, antistatic agents, flame retardants, etc.), fillers (fiber reinforcing agents such as glass fibers, inorganic fillers, etc.) and the like. Examples of the rubber include acrylic rubber; silicone rubber; SEPS, S
Styrene TPE (thermoplastic elastomer) such as EBS and SIS; olefin rubber such as IR, EPR and EPDM can be used. Examples of the lubricant include stearic acid, behenic acid, stearamic acid, methylene bisstearamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax,
Octyl alcohol, hardened oil and the like can be used. Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol and stearyl-β- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-t
Phenolic compounds such as -butyl-4-hydroxy-5-methylphenyl) propionate; N, N-di-2-
Amine compounds such as naphthyl-p-phenylenediamine and the like can be used. Examples of the plasticizer include phthalic esters such as di-2-ethylhexyl phthalate and dibutyl phthalate; phosphoric esters; adipic esters; polyethylene glycol; As the light stabilizer, for example, pt-
Butylphenyl salicylate, 2,2′-dihydroxy-4-methoxybenzophenone, 2- (2-hydroxy-4-n-octoxyphenyl) benzotriazole and the like can be used. As the coloring agent, for example, titanium oxide, carbon black, other inorganic or organic pigments, and the like can be used. As the antistatic agent, for example, stearoamidopropyldimethyl-β-hydroxyethylammonium nitrate and the like can be used. Examples of the flame retardant include organic halogen-based flame retardants such as tetrabromobisphenol A, decabromodiphenyl oxide, and brominated polycarbonate; non-halogen flame retardants such as antimony oxide, aluminum hydroxide, zinc borate, and tricresyl phosphate. Etc. can be used.

When the synthetic resin is a thermoplastic resin, the resin composition containing the multi-layered polymer particles and the synthetic resin of the present invention may be, for example, a multi-layered polymer particle, a synthetic resin, and other materials used as desired. Can be produced by thoroughly mixing the components under melt-kneading conditions. Further, when the synthetic resin is a thermosetting resin, for example, before curing of the thermosetting resin, using a solvent or the like as necessary, the multilayer polymer particles, the thermosetting resin and, if desired, A resin composition can be produced by mixing and casting other components used.

As a method for molding and processing the resin composition comprising the polymer particles having a multilayer structure of the present invention and a synthetic resin, when the synthetic resin is a thermoplastic resin, thermal molding is possible.
For example, by a molding method such as extrusion molding at 180 to 280 ° C., injection molding, hollow molding, calendar molding, compression molding, vacuum molding, foam molding, etc., powder, pellet, plate, film or sheet, pipe, It can be molded into a molded article of any shape such as a hollow shape and a box shape. In addition, when the synthetic resin is a thermosetting resin, molding at room temperature or lower is possible, and by a molding method such as extrusion molding, injection molding, hollow molding, calendar molding, compression molding, vacuum molding, or foam molding, It can be formed into a molded article of any shape such as powder, pellet, plate, film or sheet, pipe, hollow, box and the like.

The molded article comprising the resin composition comprising the multi-layered polymer particles and the synthetic resin of the present invention has the characteristics of the synthetic resin and the excellent flexibility and elastic recovery derived from the multi-layered polymer particles. Since it is exhibited, it is suitably used particularly for applications such as indoor door packing and cushions for covering handrails on stairs.

[0060]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In addition, each measured value in an Example followed the following evaluation method.

The average particle size of the multilayer polymer particles is measured by a dynamic light scattering method using a laser particle size analyzer PAR-III (manufactured by Otsuka Electronics Co., Ltd.) using a sample collected from the latex after completion of the polymerization. And analyzed and determined by the cumulant method.

The tensile strength at break, tensile elongation at break, stress at 100% elongation (100% modulus) and permanent elongation are measured according to JIS K 6301 using Autograph AG-2000B (manufactured by Shimadzu Corporation). did.

The compression set was measured using a constant strain compression molding machine (manufactured by Toyo Seiki Seisaku-sho, Ltd.) according to JIS K6301.

The hardness was measured using a type A hardness meter (manufactured by Oscar) according to JIS K6301.

The number average molecular weight of the polymer component constituting the outermost layer can be determined by using a solution obtained by sufficiently stirring a sample of the multilayer polymer particles in toluene at room temperature and then centrifuging the sample. It was measured by the method.

Example 1 Under a nitrogen atmosphere, 200 parts by weight of distilled water and sodium stearate 3.0 as an emulsifier were placed in a polymerization vessel equipped with a stirring blade, a cooling pipe and a dropping funnel.
A part by weight was added, and the mixture was heated to 70 ° C. and uniformly dissolved. Next, at the same temperature, 48 parts by weight of n-butyl acrylate, 32 parts by weight of methyl methacrylate, and 0.8 part by weight of allyl methacrylate were added, and after stirring for 30 minutes, 0.08 part by weight of potassium peroxodisulfate was added to carry out polymerization. Started. Two hours later, it was confirmed by gas chromatography that all the monomers had been consumed. Next, after adding 0.02 parts by weight of potassium peroxodisulfate to the obtained copolymer latex, methyl methacrylate 19 was added.
Parts by weight, 1 part by weight of ethyl acrylate and 0.2 part by weight of n-octyl mercaptan were added dropwise from a dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was further continued at 70 ° C. for 30 minutes, and the polymerization was terminated by confirming that the monomer was consumed by gas chromatography. The average particle size of the multilayer polymer particles in the obtained latex was 90 nm. This latex was cooled to −20 ° C. for 24 hours to aggregate, and then the aggregate was taken out and washed three times with hot water at 80 ° C. The mixture was dried under reduced pressure at 50 ° C. for 2 days to obtain two-layered polymer particles [A-1] in the form of a coagulated powder. From the powdery A-1 obtained, using a compression molding machine, 230 ° C
A sheet was prepared using the above method, and various measurements were performed. Table 1 shows the obtained measurement results.

Example 2 Under a nitrogen atmosphere, 200 parts by weight of distilled water and sodium lauryl sulfate 3.0 as an emulsifier were placed in a polymerization vessel equipped with a stirring blade, a cooling pipe and a dropping funnel.
A part by weight was added, and the mixture was heated to 70 ° C. and uniformly dissolved. Next, at the same temperature, 42 parts by weight of n-butyl acrylate, 28 parts by weight of methyl methacrylate, and 0.7 parts by weight of allyl methacrylate were added, and after stirring for 30 minutes, 0.07 parts by weight of potassium peroxodisulfate was added to carry out polymerization. Started. Two hours later, it was confirmed by gas chromatography that all the monomers had been consumed. Next, after adding 0.03 parts by weight of potassium peroxodisulfate to the obtained copolymer latex, methyl methacrylate 27 was added.
Parts by weight, 3 parts by weight of methyl acrylate and 0.3 part by weight of n-octyl mercaptan were added dropwise from a dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was further continued at 70 ° C. for 30 minutes, and the polymerization was terminated by confirming that the monomer was consumed by gas chromatography. The average particle size of the multilayer polymer particles in the obtained latex is 110 nm.
Met. The latex was cooled to −20 ° C. for 24 hours to coagulate, and then the coagulated product was taken out.
Washed twice. The mixture was dried under reduced pressure at 50 ° C. for 2 days to obtain two-layered polymer particles [A-2] in the form of a coagulated powder. From the powdery A-2 obtained, using a compression molding machine, 230
A sheet was prepared at ℃, and various measurements were performed. Table 1 shows the obtained measurement results.

Example 3 Under a nitrogen atmosphere, 200 parts by weight of distilled water and 2.5 parts of sodium stearate as an emulsifier were placed in a polymerization vessel equipped with a stirring blade, a cooling pipe and a dropping funnel.
A part by weight was added, and the mixture was heated to 70 ° C. and uniformly dissolved. Next, at the same temperature, 56 parts by weight of n-butyl acrylate, 14 parts by weight of methyl methacrylate, and 0.7 parts by weight of allyl methacrylate were added, and after stirring for 30 minutes, 0.07 parts by weight of potassium peroxodisulfate was added to carry out polymerization. Started. Two hours later, it was confirmed by gas chromatography that all the monomers had been consumed. Next, after adding 0.03 parts by weight of potassium peroxodisulfate to the obtained copolymer latex, methyl methacrylate 2 was added.
8.5 parts by weight, 1.5 parts by weight of n-butyl acrylate and 0.3 parts by weight of n-octyl mercaptan were added dropwise from a dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was further continued at 70 ° C. for 30 minutes, and the polymerization was terminated by confirming that the monomer was consumed by gas chromatography. The average particle size of the multilayer polymer particles in the obtained latex was 130 nm. This latex was cooled to -20 ° C for 24 hours to be aggregated, and then the aggregate was taken out.
The plate was washed three times with hot water at 80 ° C. The mixture was dried under reduced pressure at 50 ° C. for 2 days to obtain a coagulated powdery two-layer type polymer particle having a multilayer structure [A-
3] was obtained. A sheet was prepared from the obtained powdery A-3 at 230 ° C. using a compression molding machine, and various measurements were performed. Table 1 shows the obtained measurement results.

Example 4 In a nitrogen atmosphere, 6000 distilled water was placed in a polymerization vessel equipped with a stirring blade, a cooling pipe, and a dropping funnel.
3 parts by weight of sodium stearate as an emulsifier and 12 parts by weight of sodium lauryl sulfate were added, and the mixture was heated to 70 ° C. and uniformly dissolved. Next, at the same temperature, 2.25 parts by weight of potassium peroxodisulfate was added and stirred for 30 minutes to dissolve, and then 1350 parts by weight of n-butyl acrylate, 900 parts by weight of methyl methacrylate and 22.5 parts by weight of allyl methacrylate were dropped into the funnel. The solution was dropped over 1 hour. After dropping, 70 ° C
The reaction was further continued for 1 hour, and it was confirmed by gas chromatography that the monomer was consumed. Subsequently, potassium peroxodisulfate was added to the obtained copolymer latex in an amount of 0.1%.
After adding 75 parts by weight, 720 parts by weight of methyl methacrylate, 30 parts by weight of methyl acrylate and 7.5 parts by weight of n-octylmercaptan were added dropwise from a dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was further continued at 70 ° C. for 30 minutes, and the polymerization was terminated by confirming that the monomer was consumed by gas chromatography. The average particle diameter of the multilayer polymer particles in the obtained latex is 100 nm.
Met. The latex was cooled to −20 ° C. for 24 hours to coagulate, and then the coagulated product was taken out.
Washed twice. The mixture was dried under reduced pressure at 50 ° C. for 2 days to obtain two-layered polymer particles [A-4] in the form of aggregated powder. From the obtained powdery A-4, using a compression molding machine, 230
A sheet was prepared at ℃, and various measurements were performed. Table 1 shows the obtained measurement results.

Example 5 Under a nitrogen atmosphere, 200 parts by weight of distilled water and sodium stearate 3.0 as an emulsifier were placed in a polymerization vessel equipped with a stirring blade, a cooling pipe and a dropping funnel.
A part by weight was added, and the mixture was heated to 70 ° C. and uniformly dissolved. Then, at the same temperature, 36 parts by weight of n-butyl acrylate, 24 parts by weight of methyl methacrylate and 0.6 parts by weight of allyl methacrylate were added, and the mixture was stirred for 30 minutes.
Polymerization was initiated by adding 0.06 parts by weight of potassium peroxodisulfate. Two hours later, it was confirmed by gas chromatography that all the monomers had been consumed. Subsequently, potassium peroxodisulfate was added to the obtained copolymer latex in an amount of 0.1%.
After adding 02 parts by weight, 20 parts by weight of n-butyl acrylate and 0.2 parts by weight of allyl methacrylate were dropped from the dropping funnel over 1 hour. After dropping, at 70 ° C,
The reaction was continued for another 30 minutes, and the consumption of the monomer was confirmed by gas chromatography. Subsequently, the obtained copolymer latex was added with potassium peroxodisulfate 0.0%.
After adding 2 parts by weight, 19 parts by weight of methyl methacrylate, 1 part by weight of methyl acrylate and 0.2 part by weight of n-octyl mercaptan were added dropwise from the dropping funnel over 1 hour. After completion of the dropwise addition, the reaction was further continued at 70 ° C. for 30 minutes, and the polymerization was terminated by confirming that the monomer was consumed by gas chromatography. The average particle diameter of the multilayer polymer particles in the obtained latex was 85 nm. This latex was cooled to −20 ° C. for 24 hours to be aggregated, and then the aggregate was taken out and washed three times with hot water at 80 ° C. After drying under reduced pressure at 50 ° C. for 2 days, 3
Layer-type multilayer polymer particles [A-5] were obtained. A sheet was prepared from the obtained powdered A-5 at 230 ° C. using a compression molding machine, and various measurements were made. Table 1 shows the obtained measurement results.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the addition of n-octyl mercaptan in the polymerization reaction in the second stage was omitted. Thus, powdery two-layer type polymer particles having a multilayer structure [B-1] were obtained. The average particle size of the multilayer polymer particles in the latex obtained after the second-stage polymerization was 105 nm. The obtained powdery B-
From 1, a sheet was produced at 230 ° C. using a compression molding machine, and various measurements were made. Table 1 shows the obtained measurement results.

Comparative Example 2 The same procedure as in Example 5 was carried out except that the addition of n-octyl mercaptan in the third stage of the polymerization reaction was omitted. Thus, powdery three-layer type polymer particles having a multilayer structure [B-2] were obtained. The average particle size of the multilayer polymer particles in the latex obtained after the third stage polymerization was 95 nm. The powdery B-2 obtained
Then, a sheet was prepared at 230 ° C. using a compression molding machine, and various measurements were performed. Table 1 shows the obtained measurement results.

Comparative Example 3 A polymerization reaction was carried out in the same manner as in Example 1 except that the amount of n-octyl mercaptan added in the second stage polymerization reaction was changed from 0.2 parts by weight to 0.05 parts by weight. , Agglomeration and drying are performed to obtain a two-layered multi-layered polymer particle [B-
3] was obtained. The average particle size of the multilayer polymer particles in the latex obtained after the second stage polymerization is 100
nm. A sheet was prepared from the obtained powdery B-3 at 230 ° C. using a compression molding machine, and various measurements were performed. Table 1 shows the obtained measurement results.

(Comparative Example 4) The same procedure as in Example 5 was carried out except that the amount of sodium stearate added to the polymerization reaction system was changed from 3.0 parts by weight to 1.0 part by weight. By performing each operation of drying, three-layer type polymer particles [B-4] in the form of aggregated powder were obtained.
The average particle size of the multilayer polymer particles in the latex obtained after the third stage polymerization was 170 nm. From the obtained powdered B-4, a sheet was prepared at 230 ° C. using a compression molding machine, and various measurements were performed.
Table 1 shows the obtained measurement results.

[0075]

[Table 1]

In Table 1, "measurable" in "number average molecular weight of outermost layer" of "multilayer polymer particles"
Means that the number average molecular weight could not be measured by the GPC method under these conditions because the molecular weight was too high.

From the above Table 1, it is found that the multilayer polymer particles according to the present invention obtained when a specific amount of the molecular weight modifier is used in Examples 1 to 5 have a tensile elongation of 1 to 4 according to JIS K6301. It shows a value within the range of 45%, and is different from the multilayered polymer particles of Comparative Examples 1 to 4 in the number average molecular weight or the average particle diameter of the polymer component constituting the outermost layer as compared with the multilayered polymer particles of the present invention. It can be seen that is greatly improved. In addition, it can be seen that the multilayer polymer particles according to the present invention obtained in Examples 1 to 5 are excellent in flexibility and also have good mechanical properties such as tensile strength and tensile elongation.

(Example 6) 20 parts by weight of the multilayer polymer particles [A-1] obtained in Example 1, bead-like polyvinyl chloride (manufactured by Tosoh, TH-1000, degree of polymerization 1000)
20 parts by weight, dioctyl phthalate 20 as plasticizer
Parts by weight, 3 parts by weight of a Ca-Zn-based heat stabilizer (TMF-362M, manufactured by Tokyo Fine Chemical) and 2 parts by weight of a Ba-Zn-based heat stabilizer (O-130P, manufactured by Asahi Denka) are kneaded at 170 ° C by a hot roll. By doing so, the resin composition [A
-6] was obtained. From the obtained resin composition, a flat test piece was prepared at 180 ° C. using a compression molding machine, and various measurements were performed. Table 2 shows the obtained measurement results.

Example 7 20 parts by weight of the multilayered polymer particles [A-5] obtained in Example 5 instead of 20 parts by weight of the multilayered polymer particles [A-1] as the polymer modifier In the same manner as in Example 6 except that a polymer modifier, polyvinyl chloride, dioctyl phthalate, Ca-Z
A resin composition [A-7] was obtained by kneading the n-type heat stabilizer and the Ba-Zn-type heat stabilizer, and a flat test piece was prepared therefrom, and various measurements were made. Table 2 shows the obtained measurement results.

Comparative Example 5 Acrylonitrile-butadiene copolymer elastomer (NBR) 2 was used as a polymer modifier instead of 20 parts by weight of multilayer polymer particles [A-1].
Except for using 0 parts by weight, the same as in Example 6 above,
A resin composition [B-5] is obtained by kneading a polymer modifier, polyvinyl chloride, dioctyl phthalate, a Ca-Zn-based heat stabilizer, and a Ba-Zn-based heat stabilizer. It was fabricated and various measurements were made. Table 2 shows the obtained measurement results.

(Comparative Example 6) Bead-shaped polyvinyl chloride (manufactured by Tosoh Corporation, TH-1000, degree of polymerization: 1000) 30
Parts by weight, 30 parts by weight of dioctyl phthalate as a plasticizer, 3 parts by weight of a Ca—Zn heat stabilizer (TMF-362)
M, manufactured by Tokyo Fine Chemical Co., Ltd.) 3 parts by weight and Ba-Z
2 parts by weight of an n-type heat stabilizer (O-130P, manufactured by Asahi Denka Co., Ltd.) was kneaded at 170 ° C. with a hot roll, and the resin composition [B-
6] was obtained. From the obtained resin composition, a flat test piece was prepared at 180 ° C. using a compression molding machine, and various measurements were performed. Table 2 shows the obtained measurement results.

(Comparative Example 7) 20 parts by weight of the multilayer structure polymer particles [B-3] obtained in Comparative Example 3 instead of 20 parts by weight of the multilayer structure polymer particles [A-1] as the polymer modifier In the same manner as in Example 6 except that a polymer modifier, polyvinyl chloride, dioctyl phthalate, Ca-Z
The resin composition [B-7] was obtained by kneading the n-type heat stabilizer and the Ba-Zn-type heat stabilizer, and a flat test piece was prepared therefrom, and various measurements were made. Table 2 shows the obtained measurement results.

Comparative Example 8 20 parts by weight of the multilayered polymer particles [B-4] obtained in Comparative Example 4 instead of 20 parts by weight of the multilayered polymer particles [A-1] as the polymer modifier In the same manner as in Example 6 except that a polymer modifier, polyvinyl chloride, dioctyl phthalate, Ca-Z
A resin composition [B-8] was obtained by kneading the n-type heat stabilizer and the Ba-Zn-type heat stabilizer, and a flat test piece was prepared therefrom, and various measurements were made. Table 2 shows the obtained measurement results.

[0084]

[Table 2]

From the above Table 2, the resin composition according to the present invention comprising the polymer particles having a multilayer structure and the synthetic resin obtained in Examples 6 and 7 is the same as the resin composition obtained in Comparative Example 5 with the elastomer obtained in Comparative Example 5. Resin composition other than the present invention, Comparative Example 6
The resin composition other than the present invention which does not contain the polymer modifier obtained in the above, and the resin composition other than the present invention comprising the other multi-layered polymer particles obtained in Comparative Examples 7 and 8 and a synthetic resin It can be seen that the compression set is small and the elastic recovery performance is greatly improved as compared with Further, it can be seen that the resin composition of the multi-layered polymer particles and the synthetic resin of the present invention has good mechanical properties such as flexibility and tensile elongation.

[0086]

As described above, according to the present invention, low-hardness multilayer polymer particles having particularly excellent elastic recovery properties and excellent flexibility and mechanical properties are provided. The multilayer structure polymer particles can be easily molded, and the resulting molded product exhibits the above-mentioned excellent performance, and thus is useful as a molding material. In addition, by combining the multilayer polymer particles with a synthetic resin, it is possible to obtain a resin composition having excellent elastic recovery performance and useful as a molding material.

Claims (9)

[Claims] (1) From two or more layers having at least one of the following rubber component layers (I) inside and at least one of the following thermoplastic resin component layers (II) at least outermost: (2) The rubber component layer (I) is composed of acrylic acid ester 50 to
A monomer mixture comprising 99.99% by weight, 49.99 to 0% by weight of another monofunctional monomer copolymerizable with the acrylate ester, and 0.01 to 10% by weight of a polyfunctional monomer (3) The thermoplastic resin component layer (II) comprises 40 to 99% by weight of a methacrylate ester and another monomer copolymerizable with the methacrylate ester. A polymer layer formed by copolymerization of a monomer mixture (ii) consisting of 60 to 1% by weight of a monomer; (4) constituting the outermost layer of the thermoplastic resin component layer (II) (5) The ratio of the total weight of the rubber component layer (I) to the total weight of the thermoplastic resin component layer (II) is not more than 30,000 as measured by the GPC method. Within the range of 30/70 to 90/10 in layer (I) / layer (II) (6) Multilayer polymer particles having an average particle diameter of 150 nm or less. 2. A polymerization reaction step (a) for forming a rubber component layer (I) and a polymerization reaction step (b) for forming a thermoplastic resin component layer (II) are performed in a predetermined order. By forming at least one rubber component layer (I) inside and forming at least one thermoplastic resin component layer (II), (2) In the polymerization reaction step (a), 50 to 99.99% by weight of an acrylate ester, 49.99 to 0% by weight of other monofunctional monomer copolymerizable with ester
And (3) in the polymerization reaction step (b), 40-99% by weight of a methacrylic acid ester and Copolymerizing a monomer mixture (ii) consisting of 60 to 1% by weight of another monomer copolymerizable with the methacrylic acid ester; (4) in the polymerization reaction step (b), at least the outermost In the polymerization reaction step for forming the thermoplastic resin component layer (II), a molecular weight modifier is added to the monomer mixture (ii).
(5) The total weight of the monomer mixture (i) and the monomer mixture used in the entire polymerization reaction step The ratio of the total weight of (ii) to the monomer mixture (i) / monomer mixture (ii) was 30/70.
(6) The average particle diameter of the multilayer polymer particles at the time when all the polymerization reaction steps are completed is set to 150 nm or less;
What is claimed is: 1. A method for producing polymer particles having a multilayer structure. 3. The method according to claim 2, wherein the molecular weight regulator is an alkyl mercaptan. 4. Multilayer polymer particles obtained by the production method according to claim 2 or 3. 5. A molding material comprising the polymer particles having a multilayer structure according to claim 1 or 4. 6. A film or sheet comprising the multilayer polymer particles according to claim 1. 7. A resin composition comprising the multilayer polymer particles according to claim 1 and a synthetic resin. 8. A molding material comprising the resin composition according to claim 7. 9. A film or sheet comprising the resin composition according to claim 7.