JP2613668B2 - Nitrile polymer composition, molded article and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a nitrile polymer, a composition, a molded article, and a method for producing the same. More specifically, the present invention relates to a novel nitrile copolymer composition having excellent gas barrier properties and excellent hot-melt fluidity, a method for producing the same, and a molded article thereof.

<Conventional Technology> A nitrile resin containing 50% or more of acrylonitrile or methacrylonitrile polymerized units exhibits excellent gas barrier properties (gas impermeability) based on an intermolecular bond specific to a nitrile group. In addition, nitrile resin has acid resistance, alkali, chemical resistance to organic solvents, etc. and flexural modulus,
It has excellent mechanical properties such as tensile strength and creep resistance, and is a well-balanced resin. Because of these many useful properties, nitrile resins are widely used as materials for food packaging films, sheets, and containers.

On the other hand, in recent years, with respect to food preservation, preservation methods that do not add any additives such as antioxidants have been developed, and accordingly, there has been a demand for the development of materials with even better gas barrier properties as food packaging materials. Is difficult.

For example, the gas barrier property of an acrylonitrile resin generally increases as the content of an acrylonitrile component increases. On the other hand, such acrylonitrile resin has 20
When heated to a temperature exceeding 0 ° C., cyclization occurs due to intramolecular condensation, causing coloring and infusibility. When the content of the acrylonitrile component becomes 85% or more, the hot-melt molding of the acrylonitrile resin is substantially performed. It will be difficult.

JP-B-46-25005 discloses a method for producing a thermoplastic nitrile polymer having low gas permeability. This method uses (A) α, β such as acrylonitrile
100 parts by weight of a mixture of at least 70% by weight of olefinically unsaturated mononitrile and up to 30% by weight of (B) an olefinically unsaturated carboxylic acid ester such as methyl acrylate,
(C) in the presence of 1 to 20 parts by weight of a copolymer of a conjugated diene selected from the group consisting of butadiene and isoprene and an olefinically unsaturated nitrile, in an aqueous medium, in the presence of an emulsifier and a radical polymerization initiator, This is a method of polymerizing at a temperature of 0 to 100 ° C. in the absence of molecular oxygen. As described above, the nitrile polymer produced by this method contains a copolymer of a conjugated diene and an olefinically unsaturated nitrile.

U.S. Pat.No. 3,742,092 discloses that at least 80 parts by weight of methacrylonitrile and 0 to 20 parts by weight of a monomer selected from methyl acrylate, methyl methacrylate and styrene are used in an amount of 1 to 40 parts by weight. A method is disclosed for polymerizing in the presence of a preformed diene rubber, 5 to 160 parts by weight of a seed polymer and a radical initiator to produce an impact resistant rubber modified methacrylonitrile homo or copolymer. I have. The seed polymer is polymethacrylonitrile,
Copolymers of methacrylonitrile with up to 20% by weight of other monovinyl monomers, polystyrene, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile or copolymers of acrylonitrile with other monovinyl monomers.

The rubber-modified methacrylonitrile homo- or copolymer also contains a diene rubber as described above.

U.S. Pat.No. 3,732,336 discloses that at least 80 parts by weight of methacrylonitrile and 0 to 20 parts by weight of another monovinyl monomer are added in the presence of 5 to 160 parts by weight of a seed polymer and a radical initiator. And a method of emulsifying and producing a methacrylonitrile homo- or copolymer by polymerization. As the seed polymer, the above-mentioned U.S. Pat.
The same polymer as the seed polymer described in US Pat. No. 2,092 is used. Further, in the above specification, according to the above production method, it is described that the polymerization rate is improved,
The preparation of polymer particles in which the seed polymer is a high nitrile copolymer and the shell layer is a low nitrile copolymer is not specifically disclosed with data.

Japanese Patent Application Laid-Open No. 61-69814 discloses that acrylonitrile-based polymers have a low melt-molding property and a low molecular weight (reduced viscosity of 1.
Acrylonitrile polymers that can be melt-molded have been proposed.

Japanese Patent Application Laid-Open No. 1-236210 discloses a melt-moldable acrylonitrile polymer having a reduced viscosity of 0.1 to 1.0.
And an acrylonitrile-based polymer having an acetone-soluble portion in an amount of 5 to 20% by weight.

<Problems to be Solved by the Invention> The above proposed polymer and production method are all characterized by a resin having a high content of unsaturated nitrile in the polymer, and are disclosed in JP-B-46-25005. The gazette aims to impart impact resistance by adding a rubber component and performing graft polymerization, and U.S. Patent No. 3,742,092 discloses that a rubber component is added and graft polymerization is performed, and a seed polymer is added and impact resistance is imparted. U.S. Patent 3,732,33 with the aim of improving the polymerization rate
No. 6 also aims to improve the polymerization rate by adding a seed polymer. However, any of these methods has a problem in that the hot melt fluidity, gas barrier properties, and mechanical properties cannot be achieved in a well-balanced manner with respect to the resin composition. JP-A-61-69814 and JP-A-1-236210 are intended to reduce the molecular weight of the polymer and to impart a hot-melt fluidity, thereby avoiding a decrease in mechanical properties. No, there is a problem.

An object of the present invention is to provide a nitrile-based polymer composition having excellent hot-melt fluidity and excellent gas barrier properties and mechanical properties, and a method for producing the same. Still another object of the present invention is to provide a nitrile polymer composition that can be melt-molded into a film, sheet, bottle, fiber, or the like, and a method for producing the same.

Still another object of the present invention is to provide a nitrile-based molded article having the characteristics of the composition of the present invention.

Still other objects and advantages of the present invention will be apparent from the following description.

<Means for Solving the Problems> As a result of intensive studies, the present inventors have found that a nitrile resin is a matrix polymer of a low nitrile resin having a high hot-melt fluidity and has a low hot-melt fluidity or a hot-melt fluidity. A high-nitrile resin and a molded article with excellent balance of hot-melt fluidity, gas-barrier property and mechanical properties can be obtained by dispersing high-nitrile resin which does not show fluidity but has excellent gas barrier properties into fine particles. And found the present invention.

That is, the first aspect of the present invention is: (A) the following formula (a) Here, R ¹ is hydrogen or a methyl group, and a polymerized unit (a) represented by the following formula: Here, R ² is hydrogen or a methyl group, and R ³ is an alkyl group having 1 to 6 carbon atoms, which is composed of polymerized units represented by the following formulae, and based on the total of these polymerized units (a) and (b). When the ratio of the polymerized unit (a) is 50
(B) a polymer matrix of the above formula (a) or a polymer unit of the above formula (a) and a polymer unit of the above formula (b) in a polymer matrix of a low nitrile copolymer occupying up to 85% by weight. And fine particles of a high nitrile copolymer or a homopolymer of the polymerized unit (a), wherein the proportion of the polymerized unit (a) accounts for at least 86% by weight of the total of the polymerized units (a) and (b). A nitrile polymer composition characterized by being dispersed in a sea-island shape, and a molded article melt-molded from the polymer composition. A second aspect of the present invention is the nitrile polymer composition according to the first aspect, wherein an intermediate layer is present between the polymer matrix of the low nitrile copolymer and the fine particles of the high nitrile copolymer,
In the intermediate layer, the ratio of the polymerized unit (a) to the total of the polymerized units (a) and (b) accounts for 50 to 85% by weight, and the ratio of the polymerized unit (a) is larger than that of the polymer matrix. I do.

The first method of the present invention is as follows: (A) The following formula (a ') Here, R ¹ is hydrogen or a methyl group. It consists of a monomer represented by the following formula or a monomer (a ′) and the following formula (b ′) Here, R ² is hydrogen or a methyl group, and R ³ is an alkyl group having 1 to 6 carbon atoms. Obtaining a core layer polymer comprising a high nitrile copolymer in which the proportion of the monomer (a ') component accounts for at least 86% by weight of the total components; and (B) in the presence of the core polymer By polymerizing the monomers (a ') and (b'), the ratio of the monomer (a ') component to the total of the monomers (a') and (b ') is
A method for producing a polymer composition, comprising obtaining a shell layer polymer comprising a low nitrile copolymer occupying 50 to 85% by weight, and then (C) melt-forming the core shell type polymer particles. The second method of the present invention is as follows: (A ') In the production method according to claim 4, before the polymerization step (A) for obtaining a core layer polymer is completed, the above formulas (a') and (b) The monomers (a ′) and (b ′) are added and polymerized continuously or dividedly.
The weight of the core layer having an intermediate layer in which the proportion of the monomer (a ') component accounts for 50 to 85% by weight of the total of the components and the proportion of the monomer (a') component is larger than that of the shell layer polymer described later And (B ′) polymerizing the monomers of the above formulas (a ′) and (b ′) in the presence of the core layer polymer having the intermediate layer to obtain a monomer (a ′) Obtaining a shell layer polymer comprising a low nitrile copolymer in which the proportion of the monomer (a ') component is 50 to 85% by weight based on the total of the component (b'); It is characterized in that polymer particles are melt-molded.

The composition of the present invention comprises a two-component polymer phase of a matrix composed of a low nitrile copolymer and fine particles composed of a high nitrile copolymer, and forms a sea-island structure. The composition is derived from polymer particles having a core shell type multilayer structure, and the matrix polymer is derived from a shell layer polymer, and the fine particle polymer is derived from a core layer polymer. The feature of the present invention is that due to the adhesiveness between the core layer and the shell layer, the adhesiveness between the matrix and the fine particles in the composition is good, and it is difficult to cause problems at the time of forming such as whitening at the time of stretch molding, peeling, and the like. Also has excellent dispersibility. In particular, core-shell type multilayer particles having an intermediate layer have excellent adhesion between the core layer and the shell layer. The composition is such that the closer the intermediate layer is to the core layer, the closer to the composition of the core layer, and the closer to the shell layer, the closer to the composition of the shell layer. In the case of a gradient type intermediate layer having a gradient, the adhesiveness is further excellent.

The heat-melt fluidity and the mechanical properties greatly depend on the composition molecular weight of the matrix in the composition, and the gas barrier properties greatly depend on the composition of the fine particles in the composition. It is preferable that the fine particles are dispersed in a form spread in a plane by biaxial stretching.

The polymerized units of the above (a) and (b) are represented by the above formula (a ′),
The monomer (a ') derived from the monomer (b') is acrylonitrile or methacrylonitrile, of which acrylonitrile is preferred. The monomer (b ') is an alkyl acrylate or an alkyl methacrylate, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, methyl methacrylate, methacrylic acid Ethyl, propyl methacrylate, butyl methacrylate,
Examples thereof include amyl methacrylate and hexyl methacrylate. Of these, methyl acrylate is
It is excellent in gas barrier properties and is particularly preferable. If necessary, other copolymerizable monomers may be used in an amount of less than 5% by weight. For example, neutral monomers such as styrene, vinyl acetate, acrylamide, vinyl ethyl ether, vinyl chloride, and vinylidene chloride may be used. And acidic monomers such as acrylic acid, methacrylic acid, allylsulfonic acid, and styrenesulfonic acid, and ammonium salts and metal salts of these monomers.

The fine nitrile copolymer of the fine particles and the core layer in the composition has at least a polymerized unit of the formula (a) based on the total of the polymerized unit of the formula (a) and the polymerized unit of the formula (b).
It is a high nitrile copolymer containing 86% by weight. Preferably, the polymer of the fine particles and the core layer in the composition contains the polymerized unit of the above formula (a) at 86 to 95% by weight based on the same standard. More preferably, it is 87 to 92% by weight.

Fine particles in the composition and the high nitrile copolymer of the core layer have a reduced viscosity measured at 30 ° C in dimethylformamide.
It is in the range of 0.5 to 50 dl / g, preferably 1.0 to 40 dl / g. More preferably, it is 2.0 to 30 dl / g. The melt index value is 2 g / 10 minutes or less, preferably 0.5 g /
10 minutes or less.

The shell layer is composed of at least one layer, and the matrix in the composition and the polymer of the shell layer are also the same as those described in (a) above.
And a polymerized unit of the above formula (b). However, the polymer of the matrix and shell layers in the composition has a lower content of the polymerized unit of the above formula (a) than the polymer of the fine particles and the core layer in the composition, and the polymerized unit (a)
It is a low nitrile copolymer containing 50 to 85% by weight of the polymerized unit (a) based on the sum of (b) and (b). The polymer of the matrix and shell layer in the composition is represented by the above formula (a)
Is preferably 65 to 80% by weight, more preferably 70 to 80% by weight, based on the same standard.

The ratio of the polymerized unit (a) to the total of the polymerized units (a) and (b) is the ratio of the polymerized unit (a) and the intermediate layer present between the core layer polymer and the shell layer polymer in the matrix and the fine particles of the high nitrile copolymer in the composition. Occupies 50 to 85% by weight, and the proportion of the polymerized unit (a) is larger than that of the polymer matrix or shell layer polymer. Preferably, the content of the polymerized unit (a) is 65 to 80% by weight, more preferably 70 to 80% by weight. The intermediate layer may have a uniform composition or a composition having a concentration gradient. Preferably, the ratio of the polymerized unit (a) increases as the composition is closer to the fine particles or the core layer polymer.

It is preferable that the polymer of the fine particles and the core layer in the composition and the matrix, the polymer of the shell layer and the polymer of the intermediate layer in the composition further satisfy at least one of the following relationships.

(I) The polymerization unit of the above formula (a) which forms the polymer of the fine particles and the core layer in the composition and the matrix of the composition, the polymer of the shell layer and the polymer of the intermediate layer is a polymerization unit of acrylonitrile. And the polymerized unit of the above formula (b) is a polymerized unit composed of methyl acrylate.

(Ii) The fine particles in the composition and the high nitrile copolymer of the core layer account for 2 to 40% by weight, more preferably 5 to 20% by weight of the composition and the core shell type particles.

(Iii) 30 parts of the polymer composition in dimethylformamide,
0.3 to 5 dl / g, more preferably reduced viscosity measured at ° C.
It is in the range of 0.5-2dl / g.

(Iv) The polymer composition has a melt index value at 200 ° C. of 2 to 50 g / 10 minutes or less, more preferably 3 to 25 g / min.
10 minutes.

(V) The content of the polymerized unit (a) of the polymer of the fine particles and the core layer in the composition is at least 2 weight than the content of the polymerized unit (a) of the polymer of the matrix and the shell layer in the composition. %, More preferably at least 5% by weight, most preferably at least 10% by weight. The average particle size of the core layer is such that the average particle size of the primary particles is in the range of 0.02 to 0.8 μm, and preferably in the range of 0.04 to 0.2 μm.

The composition of the present invention can be produced by a method generally called a seed polymerization method. For example, the above equation (a)
The acrylonitrile component and / or the methacrylonitrile component of the formula (a ′) or the above-mentioned formula (a ′) so that the proportion thereof is 86 to 100% by weight based on the total amount of the polymerized units of the formulas (a) and (b). The high nitrile copolymer obtained by emulsion polymerization of the monomers represented by the formulas (a ') and (b') in an aqueous medium is used as a seed, and then the shell layer is polymerized in an aqueous medium by emulsion polymerization. Do.

A method for forming a core shell type multilayer particle having an intermediate layer is to first polymerize a core layer polymer particle composed of a high nitrile copolymer, and then use the particle as a seed to reduce the proportion of the polymerized unit (a) from the core layer polymer. The polymer of the intermediate layer comprising a small amount of the low nitrile copolymer is subjected to seed polymerization. Next, using the core layer polymer particles having the intermediate layer as seeds, a shell layer polymer composed of a low nitrile copolymer having a smaller proportion of the polymerized unit (a) than the intermediate layer polymer is obtained by sheet polymerization. Can be In the method of forming core shell type multilayer particles having a large composition gradient as the ratio of the polymerized unit (a) of the intermediate layer is closer to the core layer, the above-mentioned polymer of the intermediate layer is obtained by seed polymerization of the core layer polymer. A monomer having a lower proportion of the monomer (a ') than the unreacted monomer is continuously or dividedly added to the place where the unreacted monomer exists before the completion of the polymerization step. Seed polymerization. Next, using the core layer polymer particles having the intermediate layer as a seed, a shell layer polymer composed of a low nitrile copolymer having a smaller proportion of polymerized units (a) than the intermediate layer polymer is obtained by seed polymerization. Can be

The method of controlling the thickness, content or composition gradient of the intermediate layer is to control the polymer in the polymerization step of the intermediate layer or to further polymerize the unreacted monomer in the core layer polymerization step. It can be performed by controlling the addition rate or the addition time during continuous addition. The monomer can be supplied at once, dividedly, continuously, or the like, but continuous addition is preferable for effectively performing seed polymerization.

As the emulsifier, a known anionic emulsifier, cationic emulsifier, or nonionic emulsifier can be appropriately selected and used.
Emulsifier concentration is important in seed polymerizations, and
From 0.1 to about 2% by weight. Either too much or too little emulsifier is not preferred. Too much will generate new polymer particles and reduce seed polymerization efficiency. Conversely, if the amount is too small, the emulsion stability is reduced, which causes aggregation. Preferably, the emulsifier is added continuously. Known polymerization initiators can be used as the polymerization initiator. Mercaptans and the like can be used as the molecular weight regulator. In the polymerization of the core layer, a molecular weight regulator may or may not be used, and in the polymerization of the shell layer, it is preferable to use an appropriate concentration. The polymer emulsion obtained after the emulsion polymerization is obtained by removing unreacted monomers, coagulating, washing, dehydrating and drying by a conventional method, adding various stabilizers, pigments, etc. as necessary, and extruding the mixture into a pellet, for example, into a pellet. The compositions of the invention can be obtained and the powders can be directly molded.

As described above, the polymer composition of the present invention is preferably obtained from the core-shell type multilayer polymer particles of the method of the present invention.
In addition, for example, a separately prepared emulsion of a high nitrile copolymer and an emulsion of the low nitrile copolymer may be mixed and processed in the same manner as described above, but the film may be whitened or broken when stretched after molding. Cheap.

The composition obtained by the present invention can be easily melt-molded by a known molding method such as extrusion molding, injection molding, blow molding, and inflation molding. For example, it can be processed into primary molded products such as films, sheets, containers and the like. Further heating, uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, compression molding,
Secondary forming such as vacuum forming, calendering, and heat setting is also possible. At that time, a known molding machine can be used. In addition, a matting agent, a coloring agent, a heat stabilizer, an ultraviolet absorber and the like may be added at the time of molding according to the purpose.

The melt-molded molded article of the present invention has a sea-island 2 containing a high nitrile copolymer as an island component and a low nitrile copolymer as a sea component.
It has a phase structure. The high nitrile copolymer has a high nitrile copolymer dispersed in a polymer matrix of a low nitrile polymer in one direction by elongation or the like in a stretched form or spread in a plane. It is preferable in terms of exhibiting good gas barrier properties, and particularly preferable when the molded article is a stretched film or a stretched bottle.

The stretching temperature at the time of stretching is preferably a temperature at which the high nitrile copolymer is easily deformed. Even if the stretching temperature is low, a temperature higher than the glass transition point of the high nitrile copolymer is required. Even at a stretching temperature at which the low nitrile copolymer is easily stretched, problems such as film whitening and breakage occur at a low stretching temperature at which the high nitrile copolymer is difficult to stretch, but under appropriate stretching conditions An almost transparent film is obtained.

The molded article of the present invention is superior in bending strength and tensile elongation of the film as compared with a homogeneous copolymer obtained by the conventional method having the same composition, and has other mechanical properties such as strength and impact resistance, transparency, heat resistance, and heat resistance. It has excellent chemical properties. That is, the composition of the present invention also has good processability such as melt moldability, thermoformability, and stretchability, and can be used as a food packaging film, a container, a container for chemicals, and cosmetics.

[Examples] Hereinafter, the present invention will be described with reference to examples. “Parts” and “%” in the examples are all based on weight.

The reduced viscosity, conversion, polymer composition ratio, melt index (hereinafter abbreviated as MI), seed polymer content, emulsion particle diameter, oxygen permeation, bending properties, and film properties were measured according to the following methods.

・ Reduced viscosity: After the sample is sufficiently dried, it is dissolved in NN-dimethylformamide (hereinafter abbreviated as DMF) to 0.4 g / dl, the solution viscosity is measured at 30 ° C., and η _SP / C is calculated. Find more.

・ Conversion rate: 1 ml of the emulsion obtained by polymerization
Sampled and diluted 10 times with water 20μ
Is filled in a vial bin, vaporized at 120 ° C, and the head space gas is gas chromatographed (GC-9A, manufactured by Shimadzu Corporation).
And calculated from the residual monomer.

The conversion represents the polymer conversion based on the total amount of the charged monomers.

・ Polymer composition ratio: After thoroughly drying the sample, dissolve it in dimethyl sulfoxide and heavy dimethyl sulfoxide and
And ¹ H-NMR.

MI: According to ASTM-D1238. Conditions are temperature 200 ℃, load 12.
It was measured at 5 kg with an orifice diameter of 2.1 mmφ.

-Seed polymer content: When a molecular weight distribution curve is determined from a GPC curve measured using the following apparatus and conditions and separated into two peaks of a high molecular weight and a low molecular weight, it is represented by an area ratio to the whole on the high molecular weight side. If the polymer does not separate into two peaks, it is determined by calculation from the conversion ratio of the seed polymer and the total polymer.

Equipment: Liquid chromatograph MODEL590 (WATERS) Column: KD-800P, KD-80M, KD-802 (Showa Denko, Shode
x) Solvent: DMF (0.01N-LiBr) Flow rate: 1ml / min Temperature: 50 ° C Sample filtration: 0.5μ-PTFE FILTER (MILLIPORE) Injection volume: 0.1ml Detector: Differential refractive index detector R-401 (WATERS) Average particle diameter: Measured at a rotation speed of 7000 rpm with an ultracentrifugal automatic particle size analyzer CAPA-700 manufactured by Horiba, Ltd.

-Oxygen permeation amount: After sufficiently drying the sample (powder), it was extruded at 170 ° C using a melt extruder, and pelletized with a pelletizer. This chip is melt-molded at 180 ° C. to form a sheet. This sheet molded product was biaxially stretched to obtain a measurement film. Using this film, the amount of oxygen permeation was measured using OX-TRAN-10 manufactured by Modern Controls.
The measurement was carried out at 30 ° C. and 100% RH using a type 0 oxygen permeability meter.

-Flexural properties: The flexural modulus and flexural strength of an injection-molded sample were measured according to ASTM-D790.

-Film properties: The tensile strength and tensile elongation of the biaxially stretched film in each of the longitudinal and transverse directions were measured according to ASTM-D638.

[Example 1] [Polymerization of core layer] A mixture comprising the following components was charged into a stainless steel reactor, and the inside of the reactor was sufficiently purged with nitrogen.
Time, polymerization was carried out.

Water 147.65 parts Acrylonitrile 30.0 parts Methyl acrylate 3.3 parts Sodium persulfate 0.04 parts Ethylenediaminetetraacetic acid-potassium 0.04 parts ^* Monogen Y-100 0.64 parts ( ^* Daiichi Kogyo Seiyaku Co., Ltd., natural alcohol sulfate ester salt) And physical properties such as reduced viscosity of the polymer were measured.

 The results are shown in Table 1.

[Seed polymerization] Here, a mixture composed of the following components was continuously dropped over 3 hours (polymerization of the intermediate layer).

Water 82.05 parts Acrylonitrile 50 parts Methyl acrylate 16.67 parts n-dodecylmercaptan 2.5 parts Sodium persulfate 0.02 parts Ethylenediaminetetraacetic acid-potassium 0.02 parts Monogen Y-100 0.36 parts After dropping was completed, polymerization was further carried out at 60 ° C for 4 hours. Ivy (polymerization of shell layer). Table 1 shows the physical properties such as the conversion of the obtained emulsion. Residual monomers were removed from the emulsion, and the emulsion was salted out (coagulated) using aluminum sulfate to obtain a polymer powder.

Next, the polymer powder was sufficiently dried, extruded into a strand at 170 ° C. using a melt extruder, and pelletized with a pelletizer. Table 1 shows the physical properties of this polymer (polymer composition).

[Example 2] [Polymerization of core layer] The same procedure as in Example 1 [Polymerization of core layer] was conducted except that 0.5 part of n-dodecyl mercaptan was added to the components of Example 1 [Polymerization of core layer]. Table 1 shows the physical properties of this polymer.

[Seed polymerization] The same operation as in Example 1 [seed polymerization] was carried out except that the amount of n-dodecyl mercaptan was changed to 2.0 parts to obtain a polymer chip. Table 1 shows the physical properties of this polymer.

[Example 3] [Polymerization of core layer] Polymerization was carried out in the same manner as in Example 1 [Polymerization of core layer].
Table 1 shows the physical properties of this polymer.

[Seed polymerization] Acrylonitrile 55.3 parts, methyl acrylate 1
Polymerization was performed in the same manner as in Example 1 [seed polymerization] except that the amount was 1.4 parts, to obtain a polymer chip. Table 1 shows the physical properties of this polymer.

[Example 4] [Polymerization of seed polymer] The same procedure as in Example 1 [Polymerization of core layer] is performed, except that the polymerization time of the seed polymer is set to 8 hours, and the emulsion is once taken out. The physical properties of this polymer are shown in Table 1.

[Seed polymerization] 40.4 parts of the seed emulsion was added to the same mixture as in [Seed polymerization] of Example 1, and the same operation as in Example 1 was carried out to obtain a polymer chip. The physical properties of this polymer are shown in Table 1.

[Example 5] [Polymerization of core layer] The polymerization was carried out in the same manner as in Example 1 [Polymerization of core layer], except that the monomers were charged at 31.7 parts of acrylonitrile and 1.6 parts of methyl acrylate. The physical properties of this polymer are shown in Table 1.

[Seed polymerization] 483 parts of acrylonitrile, methyl acrylate 18.
Polymerization was carried out in the same manner as in Example 1 [seed polymerization] except that the amount was changed to 4 parts. The physical properties of this polymer are shown in Table 1.

[Example 6] [Polymerization of core layer] The same operation as in Example 1 [Polymerization of core layer] was performed except that the polymerization time was 1 hour and 30 minutes. Table 1 shows the physical properties of this polymer.

[Seed polymerization] The same operation as in Example 1 [seed polymerization] was carried out to carry out polymerization. Table 1 shows the physical properties of this polymer.

[Comparative Example 1] [Polymerization of core layer] A mixture comprising the following components was charged into a stainless steel reactor, and the inside of the reactor was sufficiently purged with nitrogen.
Time, polymerization was carried out.

Water 147.65 parts Acrylonitrile 25 parts Methyl acrylate 8.33 parts Sodium persulfate 0.04 parts Ethylenediaminetetraacetic acid-potassium 0.04 parts Monogen Y-100 0.64 parts n-dodecylmercaptan 0.83 parts The physical properties of the polymer are shown in Table 1.

[Seed polymerization] A mixture composed of the following components was continuously added dropwise over 3 hours.

Water 82.05 parts Acrylonitrile 50 parts Methyl acrylate 16.67 parts n-dodecyl mercaptan 1.67 parts Sodium persulfate 0.02 parts Ethylenediaminetetraacetic acid-potassium 0.02 parts Monogen Y-100 0.36 parts I got it. Table 1 shows the physical properties such as the conversion of the obtained emulsion. The same operation as in Example 1 was performed to obtain a polymer chip. Table 1 shows the physical properties of this polymer.

Comparative Example 2 Polymerization of Core Layer Acrylonitrile 26.67 parts, methyl acrylate 6.67
Parts, n-dodecyl mercaptan 1.39 parts, except that it was the same as Comparative Example 1 [polymerization of core layer]. Table 1 shows the physical properties of this polymer.

[Seed polymerization] Acrylonitrile 53.33 parts, methyl acrylate 13.33
Parts, n-dodecyl mercaptan 2.78 parts, and the same as Comparative Example 1 [seed polymerization]. Table 1 shows the physical properties of this polymer.

[Comparative Example 3] [Polymerization of core layer] The polymerization was performed in the same manner as in Example 1 [Polymerization of core layer], except that acrylonitrile was 25 parts, methyl acrylate was 8.33 parts, and the polymerization time was 1 hour and 30 minutes. Table 1 shows the physical properties of this polymer.

[Seed polymerization] The same operation as in Example 1 [seed polymerization] was performed except that acrylonitrile was 50 parts and methyl acrylate was 16.67 parts. Table 1 shows the physical properties of this polymer.

[Comparative Example 4] [Polymerization of core layer] Acrylonitrile 26.67 parts, methyl acrylate 6.67
The polymerization was carried out in the same manner as in Example 1 [polymerization of core layer] except that the polymerization time was 1 hour and 30 minutes. Table 1 shows the physical properties of this polymer.

[Seed polymerization] The same operation as in Example 1 [seed polymerization] was performed, except that 53.33 parts of acrylonitrile and 13.33 parts of methyl acrylate were used. Table 1 shows the physical properties of this polymer.

[Comparative Example 5] 58.2 parts of the emulsion obtained in Example 4 [polymerization of seed polymer] was mixed with 333.3 parts of the emulsion obtained in the same manner as in Comparative Example 1, and the remaining monomers were removed. Was carried out to obtain a polymer chip. Table 1 shows the physical properties of this polymer.

Example 7 Using the chip of Example 1, injection molding was performed to obtain a sample for measurement of flexural modulus and flexural strength. Further, the extruder having a T-type die is melt-molded at 180 ° C. to form a sheet having a thickness of 300 μm. The film was biaxially stretched in the same direction to obtain a biaxially stretched film having a thickness of about 50 μm. The flexural modulus, flexural strength and tensile strength and elongation of the film were measured. The results are shown in Table-2.

Comparative Example 6 The same operation as in Example 7 was performed except that a polymer was obtained in the same manner as in Comparative Example 2. The results are shown in Table-2.

[Comparative Example 7] The procedure of Example 7 was repeated, except that a polymer was obtained in the same manner as in Comparative Example 5. The results are shown in Table-2.

(Effects of the Invention) As described above, the nitrile-based polymer composition and the molded article have a high nitrile content in the polymer and have good hot-melt fluidity and thermoformability even in a range where the reduced viscosity is high, and the gas barrier property. The film is excellent in practical use because of its excellent tensile elongation and bending strength of the molded product, and the method of the present invention is industrially easy and practically useful.

[Brief description of the drawings]

FIGS. 1, 2 and 3 are schematic diagrams of the core shell type polymer particles of the present invention, wherein A and B show the high nitrile copolymer of the core layer and the low nitrile copolymer of the shell layer, respectively. C, D
Indicates a low nitrile copolymer in the intermediate layer between the core layer and the shell layer, and the AN composition in the polymer of C has a gradient from the composition of the core layer to the composition of the shell layer, and the higher the nitrile composition, the closer to the core layer. Becomes Further, the AN composition in the polymer of D is an intermediate composition between the core layer and the shell layer and is always constant. FIGS. 4, 5, and 6 are schematic diagrams showing the relationship between the distance from the center of the core shell type polymer particles 1, 2, and 3 and the AN composition in the polymer.
a, b, and c indicate the radii of the core layer, the intermediate layer, and the shell layer, respectively, and X, Y, and Z indicate the AN compositions in the respective polymers. FIGS. 7 and 8 are schematic diagrams of a composition or a molded product obtained by melt-molding the core shell type polymer particles, and FIG. 9 shows a molecular weight distribution curve of the composition by GPC analysis. A is a high nitrile copolymer composed of the core layer, and B 'is a low nitrile copolymer (B, C, C) composed of the intermediate layer and the shell layer.
D) is shown.

Claims (5)

(57) [Claims] (A) The following formula (a) Here, R ¹ is hydrogen or a methyl group, and a polymerized unit (a) represented by the following formula: Here, R ² is hydrogen or a methyl group, and R ³ is an alkyl group having 1 to 6 carbon atoms, and is composed of polymerized units (b) represented by the following formulas, and these polymerized units (a) and (b) In the polymer matrix of the low nitrile copolymer in which the proportion of the polymerized unit (a) accounts for 50 to 85% by weight based on the total of (B), (B) the polymerized unit represented by the formula (a) or the polymer (a) A) a high nitrile copolymer comprising a polymerized unit of formula (b) and a polymerized unit of the above formula (b), wherein the proportion of the polymerized unit (a) accounts for at least 86% by weight of the total of these polymerized units (a) and (b) Or a homopolymer fine particle of the polymerized unit (a) dispersed in a sea-island shape. 2. The nitrile polymer composition according to claim 1, wherein an intermediate layer exists between the polymer matrix of the low nitrile copolymer and the fine particles of the high nitrile copolymer. A nitrile-based polymer wherein the ratio of the polymerized unit (a) to the total of the polymerized units (a) and (b) accounts for 50 to 85% by weight and the ratio of the polymerized unit (a) is larger than that of the polymer matrix Polymer composition. 3. A molded article melt-molded from the polymer composition according to claim 1. (A) the following formula (a ′): Here, R ¹ is hydrogen or a methyl group. It consists of a monomer represented by the following formula or a monomer (a ′) and the following formula (b ′) Here, R ² is hydrogen or a methyl group, and R ³ is an alkyl group having 1 to 6 carbon atoms. Obtaining a core layer polymer comprising a high nitrile copolymer in which the proportion of the monomer (a ') component accounts for at least 86% by weight of the total components; and (B) in the presence of the core layer polymer, By polymerizing the monomers of the formulas (a ') and (b'), the ratio of the monomer (a ') component to the total of the monomers (a') and (b ') is
A method for producing a polymer composition, comprising: obtaining a shell layer polymer comprising a low nitrile copolymer occupying 50 to 85% by weight; and (C) melt-forming the core shell type polymer particles. 5. The method according to claim 4, wherein before the polymerization step (A) for obtaining the core layer polymer is completed, the compounds of the above formulas (a ') and (b') are The monomer (a ') is obtained by adding the monomer continuously or dividedly and polymerizing it.
An intermediate layer in which the proportion of the monomer (a ') component accounts for 50 to 85% by weight of the total of the components (b') and (b ') and the proportion of the polymer (a') component is larger than the shell layer polymer described below. (B ′) polymerizing the monomers of the above formulas (a ′) and (b ′) in the presence of the core layer polymer having the intermediate layer, A shell layer polymer comprising a low nitrile copolymer in which the ratio of the monomer (a ') component accounts for 50 to 85% by weight of the total of the components (a') and (b ') is obtained. A process for producing a polymer composition, comprising melt-molding the core shell type multilayer polymer particles.