JP2018127544A - Impact resistance improver, thermoplastic resin composition, molding and method for producing graft copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide obtain a molding in which the impact resistance of a thermoplastic resin, particularly a polyvinyl chloride resin is improved, and the high transparency is maintained.SOLUTION: An impact resistance improver contains a graft copolymer. The graft copolymer is obtained by polymerizing a vinyl monomer component (b) in the presence of a polymer mixture (A) containing a polymer (A1) mainly composed of a butadiene unit and a polymer (A2) mainly composed of a styrene unit. In the polymer mixture (A), the butadiene unit content is 70-90 mass% and the styrene unit content is 10-30 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an impact resistance improver that improves the impact resistance of a thermoplastic resin, particularly a polyvinyl chloride resin, and maintains high transparency, and a thermoplastic resin composition and a molded product containing the same.

Polyvinyl chloride resin is a resin having excellent mechanical properties and chemical properties, and thus is widely used in various fields. However, it has a problem of low impact resistance. Polyvinyl chloride resin is a material with a high refractive index, and when a general-purpose impact resistance improver is blended, the difference in refractive index between the resin and the impact resistance improver increases. The problem is that the transparency is impaired.
As a method for improving impact resistance while maintaining a high refractive index of a thermoplastic resin, in the presence of a polymer mixture containing a polymer mainly composed of butadiene units and a polymer mainly composed of styrene units. It has been shown that a graft copolymer obtained by polymerizing a vinyl monomer component is used as an impact resistance improver (Patent Document 1). However, the polyvinyl chloride resin composition obtained by this method has a problem that impact resistance is lowered.

International Publication No. 2006/026626

  An object of the present invention is to improve an impact resistance of a thermoplastic resin, particularly a polyvinyl chloride resin, and to maintain an excellent impact resistance improver, and a thermoplastic resin composition and a molded product containing the same. It is to provide.

  As a result of intensive studies, the present inventors have found that in the presence of a polymer mixture (A) containing a polymer (A1) containing a butadiene unit as a main component and a polymer (A2) containing a styrene unit as a main component, By using the graft copolymer obtained by polymerizing the vinyl monomer component (b) as an impact resistance improver, the impact resistance of the polyvinyl chloride resin can be improved and high transparency can be maintained. I found it.

That is, the present invention has the following features.
[1] A vinyl monomer component (b) in the presence of a polymer mixture (A) containing a polymer (A1) having a butadiene unit as a main component and a polymer (A2) having a styrene unit as a main component. ) Is a graft copolymer obtained by polymerizing
An impact resistance improver comprising a graft copolymer having a butadiene unit content of 70 to 90% by mass and a styrene unit content of 10 to 30% by mass in the polymer mixture (A).
[2] Aromatic vinyl monomer (b1) in vinyl monomer component (b) (100% by mass)
The impact resistance improver according to [1], in which the content of is 0 to 55% by mass and the content of the alkyl (meth) acrylate monomer (b2) is 45 to 100% by mass.
[3] The content of the polymer mixture (A) in the graft copolymer (100% by mass) is 75.
The impact resistance improver according to [1] or [2], wherein the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 25% by mass.
[4] A thermoplastic resin composition containing 90 to 99% by mass of a thermoplastic resin and 1 to 10% by mass of the impact resistance improver according to any one of [1] to [3].
[5] The thermoplastic resin composition according to [4], wherein the thermoplastic resin is a polyvinyl chloride resin.
[6] A molded product obtained by molding the thermoplastic resin composition according to [4] or [5].
[7] Polymer (A1) latex having butadiene unit as main component and monomer component having styrene as main component are mixed, and then polymerization of monomer component having styrene as main component is started. The content of butadiene units is 70 to 90
A polymer mixture (A) having a mass% and a styrene unit content of 10 to 30% by mass is produced, and the vinyl monomer component (b) is polymerized in the presence of the polymer mixture (A).
A method for producing a graft copolymer.
[8] Aromatic vinyl monomer (b1) in vinyl monomer component (b) (100% by mass)
The method for producing a graft copolymer according to [7], wherein the content of is 0 to 55% by mass and the content of the alkyl (meth) acrylate monomer (b2) is 45 to 100% by mass.
[9] The content ratio of the polymer mixture (A) in the graft copolymer (100% by mass) is 75.
The method for producing a graft copolymer according to [7] or [8], wherein the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 25% by mass. .
[10] Polymerization of a monomer component having butadiene as a main component in the presence of a polymer (A2) latex having a styrene unit as a main component in the presence of latex results in a butadiene unit content of 70 to 90% by mass, Graft copolymer for producing a polymer mixture (A) having a styrene unit content of 10 to 30% by mass and polymerizing the vinyl monomer component (b) in the presence of the polymer mixture (A) Manufacturing method.
[11] Aromatic vinyl monomer (b1) in vinyl monomer component (b) (100% by mass)
The method for producing a graft copolymer according to [10], in which the content of is 0 to 55% by mass and the content of the alkyl (meth) acrylate monomer (b2) is 45 to 100% by mass.
[12] The content of the polymer mixture (A) in the graft copolymer (100% by mass) is 75.
The method for producing a graft copolymer according to [10] or [11], wherein the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 25% by mass. .

  ADVANTAGE OF THE INVENTION According to this invention, the molded article which improves the impact resistance of a thermoplastic resin, especially a polyvinyl chloride resin, and maintains high transparency can be obtained.

<Polymer mixture (A)>
The polymer mixture (A) of the present invention contains a polymer (A1) mainly composed of butadiene units and a polymer (A2) mainly composed of styrene units.
The polymer mixture (A) may be a simple mixture of the polymer (A1) and the polymer (A2), or a polymer composite in which the polymer (A1) and the polymer (A2) are combined. There may be. More preferably, the polymer (A1) has a structure in which the domain of the polymer (A2) is formed.

By having a structure in which the domain of the polymer (A2) is formed in the polymer (A1), it is possible to increase the styrene content of the polymer mixture (A) while maintaining impact resistance. The refractive index of the whole polymer mixture (A) can be increased.
By using such a polymer mixture as an impact resistance improver, the impact resistance is improved and high transparency is maintained even for a high refractive index matrix resin such as a polyvinyl chloride resin. be able to.

The content of butadiene units in the polymer mixture (A) (100% by mass) is 70 to 90% by mass, preferably 70 to 80% by mass. The content rate of a styrene unit is 10-30 mass%, and 20-30 mass% is preferable.
If the content of butadiene units is 70% by mass or more, the effect of improving impact resistance is sufficient, and if it is 90% by mass or less, the transparency of the molded product is maintained.
If the content of the styrene unit is 10% by mass or more, the transparency of the molded product is maintained, and if it is 30% by mass or less, the effect of improving the impact resistance is sufficient.

The contents of the polymer (A1) and the polymer (A2) in the polymer mixture (A) (100% by mass) are calculated using the numerical values shown in the following (X) to (Z).
(X): 1,3-butadiene in the monomer (100% by mass) used for the polymerization of the polymer (A1)
Content of ene and styrene.
(Y): Styrene in the monomer (100% by mass) used for the polymerization of the polymer (A2) and
Content of 1,3-butadiene.
(Z): Content of butadiene unit in polymer mixture (A) (100% by mass) (70-
90 mass%) and the content of styrene units (10-30 mass%).

<Polymer (A1)>
The polymer (A1) having a butadiene unit as a main component is preferably a homopolymer or copolymer of 1,3-butadiene, and 1,3-butadiene and other vinyl monomers as necessary. Depending on the case, it is obtained by polymerizing a crosslinkable monomer.

Examples of other vinyl monomers include aromatic vinyl monomers such as styrene and α-methylstyrene; alkyl (meta) such as methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate. ) Acrylate monomers; vinyl cyanide monomers such as (meth) acrylonitrile; alkyl vinyl ether monomers such as methyl vinyl ether and butyl vinyl ether; vinyl halide monomers such as vinyl chloride and vinyl bromide; vinylidene chloride; Examples thereof include vinylidene halide monomers such as vinylidene bromide; glycidyl group-containing vinyl monomers such as glycidyl (meth) acrylate and allyl glycidyl ether.
Another vinyl monomer may be used individually by 1 type, and may use 2 or more types together.

Examples of the crosslinkable monomer include aromatic polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene; polyhydric alcohols such as ethylene glycol di (meth) acrylate and 1,3-butanediol di (meth) acrylate. And di- or tri-allyl monomers such as diallyl phthalate and triallyl triazine.
A crosslinkable monomer may be used individually by 1 type, and may use 2 or more types together.

The content of 1,3-butadiene in the monomer (100% by mass) used for the polymerization of the polymer (A1) is preferably 60% by mass or more because the impact resistance of the resulting molded article is improved. The mass% or more is more preferable.
The content of other vinyl monomers is preferably 0 to 30% by mass, and the content of crosslinkable monomers is preferably 0 to 10% by mass.

<Polymer (A2)>
The polymer having a styrene unit as a main component (A2) is preferably a homopolymer or copolymer of styrene, and styrene, another vinyl monomer if necessary, and a crosslinkable monomer if necessary. And obtained by polymerizing.

Examples of other vinyl monomers include aromatic vinyl monomers such as α-methylstyrene; alkyl (meth) acrylate monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate. Monomer; vinyl cyanide monomers such as (meth) acrylonitrile; alkyl vinyl ether monomers such as methyl vinyl ether and butyl vinyl ether; vinyl halide monomers such as vinyl chloride and vinyl bromide; vinylidene chloride and vinylidene bromide And vinylidene halide monomers such as glycidyl (meth) acrylate and glycidyl group-containing vinyl monomers such as allyl glycidyl ether; 1,3-butadiene.
Another vinyl monomer may be used individually by 1 type, and may use 2 or more types together.

  As the crosslinkable monomer, those similar to the crosslinkable monomer used for the polymerization of the polymer (A1) can be used.

The content of styrene in the monomer (100% by mass) used for the polymerization of the polymer (A2) is preferably 80% by mass or more, more preferably 90% by mass or more from the viewpoint of maintaining the transparency of the obtained molded product. preferable.
The content of other vinyl monomers is preferably 0 to 20% by mass, and the content of crosslinkable monomers is preferably 0 to 10% by mass.

<Method for producing polymer mixture (A)>
Emulsion polymerization is suitable for the production method of the polymer mixture (A), and examples thereof include the methods (1) and (2).
(1): a polymer mainly composed of butadiene units (A1) latex and styrene
A monomer component containing a main component is mixed with a monomer component containing styrene as a main component.
The polymer (A1) is impregnated, and then the monomer component mainly composed of styrene
Initiate polymerization.
(2): Polymer having a styrene unit as a main component (A2) Butadie in the presence of latex
A monomer component mainly composed of ethylene is polymerized.

  As a method for producing the polymer mixture (A), the domain size of the polymer (A2) containing styrene units as the main component is smaller than the particle size of the polymer (A1) containing butadiene units as the main component. The method of (1) is preferable because a sufficiently small domain can be formed compared to the wavelength of.

<Graft copolymer>
The graft copolymer of the present invention is obtained by polymerizing the vinyl monomer component (b) in the presence of the polymer mixture (A). Polymerizing the vinyl monomer component (b) in the presence of the polymer mixture (A) is intended to graft the vinyl monomer component (b) to the polymer mixture (A). The vinyl monomer component (b) does not graft onto the polymer mixture (A), and a free polymer polymerized alone can be produced as a by-product. For this reason, it may be obtained as a mixture of a graft copolymer and a free polymer.
In the present invention, the above free polymer is also referred to as a graft copolymer. The polymer obtained by polymerizing the vinyl monomer component (b) is referred to as a graft portion including the above free polymer.

75-90 mass% is preferable and, as for the content rate of the polymer mixture (A) in a graft copolymer (100 mass%), 75-85 mass% is more preferable. 10-25 mass% is preferable and, as for the content rate of the graft part obtained by superposing | polymerizing a vinyl monomer component (b), 15-25 mass% is more preferable.
When the content of the polymer mixture (A) is 75% by mass or more, the effect of improving the impact resistance is sufficient, and when it is 90% by mass or less, the handleability as a graft copolymer does not deteriorate, and the matrix Dispersibility in the resin does not decrease.
If the content of the graft part is 10% by mass or more, the handleability as a graft copolymer does not decrease, and the dispersibility in the matrix resin does not decrease. The improvement effect is sufficient.

The mass average particle diameter of the graft copolymer is preferably 0.05 μm or more, and more preferably 0.08 μm or more. Moreover, 0.3 micrometer or less is preferable, 0.2 micrometer or less is more preferable, 0.15 micrometer or less is still more preferable.
If the mass average particle diameter of the graft copolymer is 0.05 μm or more, the effect of improving the impact resistance is sufficient, and the dispersibility in the matrix resin does not deteriorate. If the mass average particle diameter of the graft copolymer is 0.3 μm or less, the transparency of the molded product is maintained, and in particular, the haze of the molded product does not increase.

<Vinyl monomer component (b)>
The vinyl monomer component (b) contains one or more vinyl monomers. Examples of the vinyl monomer include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyl toluene; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl. Examples include alkyl (meth) acrylate monomers such as (meth) acrylate; vinyl cyanide monomers such as (meth) acrylonitrile.

  The vinyl monomer component (b) preferably contains an aromatic vinyl monomer (b1) and an alkyl (meth) acrylate monomer (b2). The vinyl monomer component (b) (100% by mass) It is more preferable that the content of the aromatic vinyl monomer (b1) is 0 to 55% by mass and the content of the alkyl (meth) acrylate monomer (b2) is 45 to 100% by mass.

If the content of the aromatic vinyl monomer (b1) in the vinyl monomer component (b) (100% by mass) is 55% by mass or less, the transparency of the molded product can be maintained and the thermoplastic resin can be used. Since the compatibility is increased, the effect of improving the impact resistance is sufficient.
If the content of the alkyl (meth) acrylate monomer (b2) is 45% by mass or more, the compatibility with the thermoplastic resin will be high, and the effect of improving impact resistance will be sufficient, and the molded product will be transparent. Sex is maintained.

The vinyl monomer component (b) has a content of the aromatic vinyl monomer (b1) in the vinyl monomer component (b) (100% by mass) of 0 to 55% by mass, alkyl (meth). The content of the acrylate monomer (b2) may be 45 to 100% by mass, and the content of the other vinyl monomer (b3) may be 0 to 20% by mass.
If the content of the other vinyl monomer (b3) in the vinyl monomer component (b) (100% by mass) is 20% by mass or less, the effect of improving impact resistance is sufficient, and the molded product Transparency is maintained.

Furthermore, the vinyl monomer component (b) can contain a crosslinkable monomer as required.
As the crosslinkable monomer, those similar to the crosslinkable monomer used for the polymerization of the polymer (A1) can be used.

<Method for producing graft copolymer>
As a method for polymerizing the vinyl monomer component (b) in the presence of the polymer mixture (A), for example, the vinyl monomer component (b) can be added in one step or in the presence of the polymer mixture (A) latex. A method of graft polymerization in multiple stages can be mentioned. From the viewpoint of improving impact resistance and maintaining the transparency of the molded product, it is preferable to graft-polymerize the vinyl monomer component (b) in three stages.

When the vinyl monomer component (b) is graft polymerized in three stages, it is preferably carried out by the following method.
First stage: alkyl (meth) acrylate monomer (b2) or alkyl (meth)
Consists of acrylate monomer (b2) and other vinyl monomer (b3)
A monomer mixture is used. Alkyl (meth) acrylate monomer (b2)
Since the compatibility with polyvinyl chloride resin is improved, methyl methacrylate
Rate is preferred.
Second stage: aromatic vinyl monomer (b1), or aromatic vinyl monomer (b1) and its
A monomer mixture composed of another vinyl monomer (b3) is used.
Third stage: alkyl (meth) acrylate monomer (b2) or alkyl (meth)
Consists of acrylate monomer (b2) and other vinyl monomer (b3)
A monomer mixture is used. Alkyl (meth) acrylate monomer (b2)
Since the compatibility with polyvinyl chloride resin is improved, methyl methacrylate
Rate is preferred.

  By adopting such a polymerization method, the impact resistance can be improved and the compatibility with the thermoplastic resin can be improved by the first stage graft polymerization, and the refractive index of the graft portion can be increased by the second stage graft polymerization. The appearance of the molded product can be improved by the third stage graft polymerization.

In addition, when employing such a polymerization method, the monomer or monomer mixture used for the first stage graft polymerization is 10 to 50% by mass, the monomer or monomer mixture used for the second stage graft polymerization is It is preferable that the monomer or the monomer mixture used for the graft polymerization in the third stage is 0 to 55% by mass, and 5 to 30% by mass (the total amount of monomers used is 100% by mass).
If the monomer or monomer mixture used in the first stage graft polymerization is 10% by mass or more, the effect of improving impact resistance is sufficient.

If the monomer or monomer mixture used for the second stage graft polymerization is 55% by mass or less, the effect of improving the transparency and impact resistance of the molded article is sufficient.
If the monomer or monomer mixture used in the third stage of graft polymerization is 5% by mass or more, the appearance of the molded product does not deteriorate, and if it is 30% by mass or less, the graft copolymer in the matrix resin Dispersibility does not decrease.

The obtained latex of the graft copolymer was coagulated by separating it into hot water in which an acid such as sulfuric acid or hydrochloric acid; an alkaline earth metal salt such as calcium chloride, calcium acetate or magnesium sulfate was dissolved. It can be obtained as a graft copolymer powder by drying.
In the step of coagulating the latex of the graft copolymer, an alkali metal salt such as sodium carbonate or sodium sulfate may be used in combination. It is also possible to obtain powder directly from the latex by a direct drying method such as spray drying.

<Impact resistance improver>
The impact resistance improver of the present invention is composed of the graft copolymer of the present invention.
The graft copolymer of the present invention contains, as a polymer mixture (A), a polymer (A1) mainly composed of butadiene units and a polymer (A2) mainly composed of styrene units, A butadiene polymer exhibits a high refractive index (1.52) among rubber polymers having a glass transition temperature of room temperature (25 ° C.) or lower, which is advantageous for producing an impact resistance improver having a high refractive index. is there. Since the styrene polymer exhibits a high refractive index (1.59), it is advantageous for increasing the refractive index of the impact resistance improver.

The impact resistance improver of the present invention has excellent compatibility with a matrix resin such as a polyvinyl chloride resin having a polar group by using methyl methacrylate in the graft portion, and is easy to handle as an impact resistance improver. Excellent.
In addition, by using a component having a low glass transition temperature, such as a butadiene polymer, and a component having a high glass transition temperature, such as a styrene polymer and a methyl methacrylate polymer, it has an excellent impact resistance improvement effect, Excellent handling as an impact resistance improver.

Although there is no restriction | limiting in particular in the thermoplastic resin which mix | blends the impact resistance improving agent of this invention, The thing with a refractive index of 1.52-1.54 is preferable, and a polyvinyl chloride resin (refractive index: 1.53-1. 54) is more preferable.
When the refractive index of the thermoplastic resin is less than 1.52, it is possible to achieve the effect of improving the impact resistance and maintaining the transparency of the molded product without using the impact resistance improver of the present invention. . When the refractive index of the thermoplastic resin exceeds 1.54, it becomes difficult to maintain the transparency of the molded product even if the impact resistance improver of the present invention is used.

<Polyvinyl chloride resin>
The polyvinyl chloride resin used in the present invention is a known polyvinyl chloride resin. The mass average molecular weight is preferably 80,000 to 160,000, more preferably 80,000 to 100,000.

  The polyvinyl chloride resin is produced by a known method. For example, a method in which a mixed gas of heated acetylene and hydrogen chloride is brought into contact with a catalyst, ethylene is chlorinated to produce ethane dioxide, and this ethane dioxide is used. Examples include a method of thermal decomposition.

<Thermoplastic resin composition>
The thermoplastic resin composition of the present invention contains a thermoplastic resin and an impact resistance improver.
The content of the thermoplastic resin in the thermoplastic resin composition (100% by mass) is 90 to 99% by mass, preferably 95 to 98% by mass, and more preferably 95.5 to 97.5% by mass. The content of the impact resistance improver in the thermoplastic resin composition (100% by mass) is 1 to 10% by mass, preferably 2 to 5% by mass, and more preferably 2.5 to 4.5% by mass. .
If the content of the thermoplastic resin in the thermoplastic resin composition (100% by mass) is 90% by mass or more, the transparency of the molded product is maintained, and if it is 99% by mass or less, the impact resistance is sufficiently improved. It becomes. If the content of the impact resistance improver is 1% by mass or more, the effect of improving the impact resistance is sufficient, and if it is 10% by mass or less, the transparency of the molded product is maintained.

  Examples of the method for preparing the thermoplastic resin composition of the present invention include known methods used for preparing ordinary resin compositions. For example, an impact resistance improver and a thermoplastic resin are charged into a V-type blender, ribbon mixer, tumbler or the like and mixed uniformly, and then melt-kneaded with a single-screw or twin-screw extruder. Moreover, after kneading a part of the components in advance, the remaining components may be added and kneaded.

<Molded product>
The molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention. As the molding method, known methods such as an extrusion molding method, an injection molding method, and a compression molding method can be used. It can also be applied to blow molding, vacuum molding, and the like.
Since the molded article is excellent in impact resistance and transparency, it can be used in a wide range of fields such as applications where transparency and color development are required, such as OA equipment and housings.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
“Parts” and “%” in the examples represent “parts by mass” and “% by mass”, respectively.

[Measurement of polymerization rate]
The polymerization rate of the polymer was measured as follows.
An inhibitor (hydroquinone) was added to the polymer latex, and the solid content was measured by heating at 180 ° C. for 30 minutes. The polymerization rate of the polymer was determined by comparison with the calculated value from the charged amount.

[Measurement of mass average particle diameter]
The mass average particle diameter was measured by the following procedure.
A polymer latex diluted with distilled water to a concentration of about 3% was used as a sample and measured using a CHDF2000 particle size distribution meter manufactured by MATEC, USA.
The measurement conditions were standard conditions recommended by MATEC. That is, using a dedicated particle separation capillary cartridge and carrier liquid, the liquidity is almost neutral, the flow rate is 1.4 ml / min, the pressure is about 4000 psi (2600 KPa), and the temperature is kept at 35 ° C., and the sample is 0.1 ml. Was used for the measurement.
As a standard substance, a total of 12 monodisperse polystyrenes having a known particle diameter manufactured by DUKE Corporation in the United States were used within a range of 0.02 to 0.8 μm.

(Example 1) Graft copolymer (G-1)
Production of polymer (A1-1) latex:
The following first monomer mixture was charged into a 70 L autoclave equipped with a stirrer, a monomer addition port, and a thermometer, and the internal temperature was raised to 43 ° C. while stirring.
First monomer mixture:
1,3-butadiene 194 parts Styrene 6 parts t-dodecyl mercaptan 1.0 part diisopropylbenzene hydroperoxide 1.0 part sodium dodecylbenzenesulfonate 2.0 parts sodium hydroxide 0.02 parts deionized water 585.98 parts

Then, the following first reducing agent mixture was added to initiate polymerization.
First reducing agent mixture:
Ferrous sulfate 0.002 part EDTA · 2Na 0.006 part Rongalit 0.3 part Deionized water 9.692 part Next, the internal temperature was raised to 65 ° C. and held for 10 hours to obtain a polymer (A1-1 ) Latex was obtained. The polymerization rate of the obtained polymer (A1-1) was 95%.

Production of polymer mixture (A-1) latex:
The following latex mixture was charged at 20 ° C. into a 5 L separable flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, monomer addition port, and thermometer.
Latex mixture:
880 parts of polymer (A1-1) latex
(Solid content: 220 parts)
Styrene 80 parts t-Butyl hydroperoxide 0.4 parts Deionized water 248.4 parts

After stirring for 1 hour while maintaining the temperature of 20 ° C., the internal temperature was raised to 55 ° C., the following second reducing agent mixture was added, and polymerization of styrene was started.
Second reducing agent mixture:
Rongalite 0.3 part Deionized water 9.7 part The internal temperature was raised to 75 ° C. and held for 90 minutes to obtain a polymer mixture (A-1) latex.

Production of graft copolymer (G-1):
Subsequently, polymerization was carried out by dropping the following second monomer mixture at 75 ° C. over 15 minutes to the total amount of the polymer mixture (A-1) latex (1218.8 parts / solid content: 300 parts). .
Second monomer mixture:
Methyl methacrylate 31 parts Ethyl acrylate 5 parts t-butyl hydroperoxide 0.4 parts The mixture was held at 75 ° C for 90 minutes to complete the first stage graft polymerization.

Subsequently, the following 3rd monomer mixture was dripped at 75 degreeC over 60 minutes, and superposition | polymerization was performed.
Third monomer mixture:
Styrene 54 parts t-butyl hydroperoxide 0.4 parts The mixture was held at 75 ° C. for 120 minutes to complete the second stage graft polymerization.

Subsequently, the following 4th monomer mixture was dripped over 10 minutes at 75 degreeC, and superposition | polymerization was performed.
Fourth monomer mixture:
Methyl methacrylate 10 parts t-butyl hydroperoxide 0.4 parts The mixture was held at 75 ° C. for 90 minutes to complete the third stage of graft polymerization to obtain a graft copolymer (G-1) latex. The polymerization rate of the obtained graft copolymer (G-1) was 99% or more, and the mass average particle diameter of the graft copolymer (G-1) was 0.1 μm.

  100 parts of the obtained graft copolymer (G-1) latex was put into 200 parts of a 5% aqueous calcium acetate solution heated to 80 ° C. for coagulation. The coagulated product was washed with warm water and then dried to obtain a powder of the graft copolymer (G-1).

(Comparative Example 1) Graft copolymer (G-2)
Polymer mixture (A-1) A graft copolymer (G-2) was obtained in the same manner as in Example 1 except that the latex mixture used in the production of the latex was changed to the following composition.
Latex mixture:
720 parts of polymer (A1-1) latex
(Solid content: 180 parts)
Styrene 120 parts t-butyl hydroperoxide 0.4 parts deionized water 248.4 parts

(Comparative Example 2) Graft copolymer (G-3)
The polymer (A1-1) latex is not passed through the polymer mixture (A-1), but the following second to fourth monomer mixtures used for the first to third stage graft polymerization are polymerized. Produced a graft copolymer (G-3) in the same manner as in Example 1.
1200 parts of polymer (A1-1) latex
(Solid content: 300 parts)
Second monomer mixture:
Methyl methacrylate 35 parts Ethyl acrylate 5 parts t-butyl hydroperoxide 0.4 parts Third monomer mixture:
Butyl acrylate 50 parts t-butyl hydroperoxide 0.4 parts Fourth monomer mixture:
Methyl methacrylate 10 parts t-butyl hydroperoxide 0.4 parts

  Table 1 shows a summary of the compositions, refractive indexes (calculated values), and mass average particle diameters of the graft copolymers (G-1) to (G-3).

(Example 2, Comparative Examples 3-5)
A mixture of 100 parts of polyvinyl chloride resin (TK-700: Shin-Etsu Chemical Co., Ltd.) as a thermoplastic resin, 1 part of dibutyltin mercapto as a stabilizer, and glycerin monostearate and synthetic polyethylene wax as a lubricant 2 .5 parts was blended. Graft copolymers (G-1) to (G-3) were blended as impact resistance improvers to this blend. The polyvinyl chloride resin and the graft copolymer were blended at a ratio shown in Table 2 with the total amount being 100%.
Test pieces were prepared from the obtained polyvinyl chloride resin composition and evaluated as follows. The evaluation results are shown in Table 2.

(1) Izod test (impact resistance test)
The polyvinyl chloride resin composition was kneaded for 3 minutes at 190 ° C. using an 8-inch hot roll, and press molding was performed under the conditions of 190 ° C., 5 MPa, and 5 minutes by hot pressing to prepare an Izod test piece.
An Izod test was performed in accordance with ASTM D256. The test was performed using a test piece with a notch having a thickness of 1/4 inch. The measurement was performed at 25 ° C.

(2) Transparency (total light transmittance, haze)
The same operation as the preparation of the Izod test piece was performed, and a 50 mm square and 4 mm thick sample for transparency evaluation was molded.
Using a haze meter HR-100 (manufactured by Murakami Color Research Laboratory Co., Ltd.), the total light transmittance and haze were measured according to JIS-K7105.

From Example 2, it can be seen that the impact resistance improver of the present invention improves impact resistance and maintains high transparency.
Since Comparative Example 3 has a high content of styrene in the polymer mixture (A), the transparency is high, but the impact resistance is low, and compared to the impact resistance improver of the present invention, the impact resistance and transparency are low. The balance of is poor.
Since Comparative Example 4 has a low styrene content in the polymer mixture (A), the transparency is poor as compared with the impact resistance improver of the present invention.

  As is apparent from the above, the impact resistance improver of the present invention can improve the impact resistance of thermoplastic resins, particularly polyvinyl chloride resins, and maintain high transparency of the molded product.

The impact resistance improver of the present invention can improve the impact resistance of a thermoplastic resin, particularly a polyvinyl chloride resin, and can maintain high transparency of a molded product.
The thermoplastic resin composition blended with the impact resistance improver of the present invention is excellent in impact resistance and can maintain transparency. Therefore, applications such as optical media materials that require transparency, housings, etc. It can be used in a wide range of fields, such as applications where color development is required.

Claims (12)

The vinyl monomer component (b) is polymerized in the presence of a polymer mixture (A) containing a polymer (A1) having a butadiene unit as a main component and a polymer (A2) having a styrene unit as a main component. A graft copolymer obtained by
An impact resistance improver comprising a graft copolymer having a butadiene unit content of 70 to 90 mass% and a styrene unit content of 10 to 30 mass% in the polymer mixture (A).   In the vinyl monomer component (b) (100% by mass), the content of the aromatic vinyl monomer (b1) is 0 to 55% by mass, and the content of the alkyl (meth) acrylate monomer (b2) is The impact resistance improver according to claim 1, which is 45 to 100% by mass.   The content of the polymer mixture (A) in the graft copolymer (100% by mass) is 75 to 90% by mass, and the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 10%. The impact resistance improver according to claim 1 or 2, which is 25% by mass.   A thermoplastic resin composition comprising 90 to 99% by mass of a thermoplastic resin and 1 to 10% by mass of the impact resistance improver according to any one of claims 1 to 3.   The thermoplastic resin composition according to claim 4, wherein the thermoplastic resin is a polyvinyl chloride resin.   A molded product obtained by molding the thermoplastic resin composition according to claim 4 or 5.   By mixing the polymer (A1) latex having a butadiene unit as a main component and a monomer component having a styrene as a main component, and then starting polymerization of the monomer component having a styrene as a main component, A polymer mixture (A) having a butadiene unit content of 70 to 90% by mass and a styrene unit content of 10 to 30% by mass is produced, and in the presence of the polymer mixture (A), a vinyl monomer is produced. A method for producing a graft copolymer, wherein the component (b) is polymerized.   In the vinyl monomer component (b) (100% by mass), the content of the aromatic vinyl monomer (b1) is 0 to 55% by mass, and the content of the alkyl (meth) acrylate monomer (b2) is The manufacturing method of the graft copolymer of Claim 7 which is 45-100 mass%.   The content of the polymer mixture (A) in the graft copolymer (100% by mass) is 75 to 90% by mass, and the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 10%. The manufacturing method of the graft copolymer of Claim 7 or 8 which is 25 mass%.   Polymer (A2) containing styrene units as the main component In the presence of latex, the monomer component containing butadiene as the main component is polymerized, whereby the content of butadiene units is 70 to 90% by mass and the content of styrene units. A method for producing a graft copolymer, comprising producing a polymer mixture (A) having a rate of 10 to 30% by mass and polymerizing the vinyl monomer component (b) in the presence of the polymer mixture (A).   In the vinyl monomer component (b) (100% by mass), the content of the aromatic vinyl monomer (b1) is 0 to 55% by mass, and the content of the alkyl (meth) acrylate monomer (b2) is The manufacturing method of the graft copolymer of Claim 10 which is 45-100 mass%.   The content of the polymer mixture (A) in the graft copolymer (100% by mass) is 75 to 90% by mass, and the content of the graft part obtained by polymerizing the vinyl monomer component (b) is 10 to 10%. The manufacturing method of the graft copolymer of Claim 10 or 11 which is 25 mass%.