JP2001089591A - Expandable vinyl chloride-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an expandable vinyl chloride-based resin composition capable of remarkably improving the expansion ratio of the vinyl chloride-based resin. SOLUTION: This composition comprises 100 pts.wt. of vinyl chloride-based resin, 5-30 pts.wt. of (meth)acrylate-based copolymer, 0.5-15 pts.wt. of water and 0-20 pts.wt. of a thermally decomposable blowing agent. The (meth)acrylate- based copolymer is a polymer compound obtained by adding 0-50 pts.wt. of (b) a monomer mixture in such a way that the total amount of monomer mixtures (a) and (b) is 100 pts.wt. to polymerize the monomer mixture (b) in the presence of (co)polymer latex obtained by emulsion polymerization of 50-100 pts.wt. of (a) a monomer mixture comprising 50-100 wt.% of methyl methacrylate and 0-50 wt.% of at least one monomer selected from the group consisting of a methacrylate except methyl methacrylate and an acrylate. The monomer mixture (b) comprises 0-50 wt.% of methyl methacrylate and 50-100 wt.% of at least one monomer selected from the group consisting of a methacrylate except methyl methacrylate and an acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a foamable vinyl chloride resin composition. More specifically, it has excellent workability,
The present invention relates to a foamable vinyl chloride-based resin composition which gives a high-magnification foam molded article having excellent physical properties.

[0002]

2. Description of the Related Art Vinyl chloride resins are used for building materials and other materials because they give molded products having excellent physical properties such as impact resistance and heat resistance and chemical properties such as solvent resistance, acid resistance and alkali resistance. Widely used in the field. In recent years, as a means of reducing the weight of vinyl chloride resins and lowering the cost of molded products, a foam molding method has attracted attention,
There is a strong demand from the market for molded articles of vinyl chloride resin with high magnification.

[0003] In the foam molding of the vinyl chloride resin, it is generally known to use a processability improver containing methyl methacrylate as a main component in combination with a foaming agent.

It is known that when a volatile organic solvent-based foaming agent such as an aliphatic hydrocarbon or an aliphatic halogenated hydrocarbon is used as the foaming agent, high magnification foaming is possible.

For example, JP-B-60-10540 and JP-B-58-40986 disclose that a vinyl chloride resin is impregnated with an organic solvent having a boiling point of 90 ° C. or less such as butane or dichlorofluoromethane as a foaming agent. It is described that by directly injecting the mixture into an extruder during extrusion processing, a foamed product having a high expansion ratio of several tens of times can be obtained.

However, the use of an organic solvent-based foaming agent is disadvantageous in terms of cost since equipment such as explosion proof is required for molding as compared with water.

On the other hand, a pyrolytic organic blowing agent as a blowing agent,
At present, when using a thermal decomposition type foaming agent such as a thermal decomposition type inorganic foaming agent, if the surface of the molded article is to be made uniform and the foaming cells are to be kept uniform and fine, the expansion ratio is about 3 to 4 times or more. It is difficult to raise.

For example, Japanese Patent Publication No. 9540/1988 discloses a methacrylate resin (with a degree of polymerization of 2,000 to 30,000,
A polymethyl methacrylate having a weight average molecular weight of 200,000 to 3,000,000), a pyrolytic organic blowing agent such as azodicarbonamide, a pyrolytic inorganic blowing agent such as sodium bicarbonate, and a filler such as calcium carbonate. Degree of polymerization 5
A foamable vinyl chloride-based resin composition obtained by adding to a vinyl chloride-based resin of No. 00 to 800 is described. When molded using this foamable vinyl chloride-based resin composition, it is described that a foam molded article having uniform and fine foam cells, excellent surface properties, and excellent surface hardness can be obtained. It is about 3 to 4 times.

Japanese Patent Application Laid-Open No. Hei 6-9813 discloses a vinyl chloride foaming foam obtained by adding a methacrylate resin and a bicarbonate of 10 μm or less as a pyrolytic foaming agent to the vinyl chloride resin. A resin composition is described. It is described that when molded using the vinyl chloride resin composition for foaming, a foamed molded article having uniform and fine foamed cells and having good thermal stability and weather resistance is obtained. Are not detailed.

Furthermore, Japanese Patent Application Laid-Open No. 9-151269 discloses a foaming chloride obtained by blending a polymethyl methacrylate resin having a weight average molecular weight of 4.5 to 7,000,000 and a pyrolytic blowing agent with a vinyl chloride resin. A vinyl resin composition is described. It is described that when molded using the vinyl chloride resin composition for foaming, an injection foamed molded article having uniform foam cells and free from resin decomposition is obtained. However, the obtained expansion ratio is about 2 to 3 times.

Japanese Patent Application Laid-Open No. 7-278336 describes that a high-magnification foam can be obtained by adding water to a thermoplastic elastomer and foaming it. As the thermoplastic elastomer, a resin in which a rubber component such as NBR is copolymerized with vinyl chloride is used, and an ordinary vinyl chloride resin is not used.

Japanese Patent Application Laid-Open No. 9-194620 discloses that a foamed molded article can be obtained by irradiating a microwave to a thermoplastic resin composition obtained by adding a substance containing water to a thermoplastic resin. However, water is not used, and the obtained expansion ratio is about 2 to 5 times.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the expansion ratio by using water or using water and a pyrolytic foaming agent without using an organic solvent-based blowing agent in foam molding. An object of the present invention is to provide a foamable vinyl chloride resin composition which can be significantly improved.

[0014]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a vinyl chloride resin has a specific (meth) acrylate copolymer and water, or a pyrolytic foaming agent together with water. It has been found that the addition of a compound can greatly increase the expansion ratio as compared with a conventionally known composition, thereby completing the present invention.

That is, the present invention relates to (A) 100 parts by weight (hereinafter referred to as "parts") of a vinyl chloride resin, and (B) 50 to 100% by weight of methyl methacrylate (hereinafter referred to as "%") as a processability improver. A monomer mixture (a) 50 comprising 0 to 50% of a monomer selected from methacrylates and acrylates excluding methyl acrylate and 0 to 20% of a vinyl monomer copolymerizable therewith; -10
In the presence of a (co) polymer latex obtained by emulsion polymerization of 0 part, at least one selected from 0 to 50% of methyl methacrylate and at least one of methacrylate and acrylate except methyl methacrylate. Monomer 5
0 to 100% and a vinyl monomer 0 copolymerizable therewith
(Meth) acrylate copolymer 0 which is a polymer mixture obtained by adding and polymerizing 0 to 50 parts of a monomer mixture (b) consisting of 0 to 20% so that the total amount becomes 100 parts. 0.5 to 30 parts and water as a foaming agent 0.5 to 0.5 part
A foamable vinyl chloride-based resin composition (Claim 1) containing 15 parts and 0 to 20 parts of a pyrolytic foaming agent, and a processability improver (B) comprising 50 to 100% of methyl methacrylate and methacryl 0-50% of a monomer selected from methacrylates and acrylates excluding methyl acrylate
And 50 to 100 parts of a monomer mixture (a) consisting of 0 to 20% of a vinyl monomer copolymerizable therewith and obtained by emulsion polymerization, and 0.1 g of the polymer is dissolved in 100 ml of chloroform. The specific viscosity of the dissolved solution at 30 ° C. is 0.7
In the presence of the latex of the (co) polymer described above, 0 to 50% of methyl methacrylate and at least one kind of monomer 50 to 100 selected from methacrylate and acrylate except methyl methacrylate. % And a monomer mixture (b) consisting of 0 to 20% of a vinyl monomer copolymerizable therewith so as to have a total amount of 100 parts, and a polymer obtained by polymerization. A (meth) acrylic acid ester-based copolymer, wherein a specific viscosity at 30 ° C. of a solution obtained by dissolving 0.1 g of the polymer mixture in 100 ml of chloroform is 0.5 or more. The present invention relates to the foamable vinyl chloride resin composition according to claim 1 (claim 2).

[0016]

DETAILED DESCRIPTION OF THE INVENTION A feature of the present invention is that a (co) polymer obtained by emulsion polymerization of a monomer mixture (a) containing a predominant amount of methyl methacrylate is used as a first-stage component, followed by methacrylic acid. (Co) polymers obtained by adding and polymerizing a monomer mixture (b) containing a predominant amount of at least one monomer selected from methacrylic acid esters and acrylic acid esters excluding methyl acrylate (hereinafter referred to as “copolymer”) , Also referred to as a second-stage polymer), which contains a predominant amount of methyl methacrylate (co)
0.1 g of a polymer (hereinafter also referred to as a first-stage polymer)
The specific viscosity at 30 ° C. of the solution dissolved in 0 ml of chloroform is 0.7 or more.
30 g of a solution of 1 g in 100 ml of chloroform.
It is to use a two-stage polymer mixture having a specific viscosity at 0.5 ° C of 0.5 or more as a processability improver for a vinyl chloride resin. By using the two-stage polymer mixture as a processability improver for a vinyl chloride resin and using water or water and a pyrolytic foaming agent as a foaming agent, excellent physical and chemical properties inherent to the vinyl chloride resin are obtained. The effect that the expansion ratio at the time of foam molding can be improved without impairing the characteristics can be remarkably exhibited by adding a small amount.

The vinyl chloride resin (A) used in the present invention is not particularly limited, and any conventional vinyl chloride resin can be used. It is preferably a (co) polymer comprising 0 to 20% by weight (hereinafter referred to as%) and other monomer units copolymerizable with vinyl chloride.

Other monomers copolymerizable with the vinyl chloride include, for example, vinyl acetate, propylene, styrene, acrylates (eg, methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, etc.). Alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, etc.). These may be used alone or in combination of two or more.

The average degree of polymerization of the vinyl chloride resin is not particularly limited, but usually about 400 to 800 is used.

Examples of such a vinyl chloride resin include a copolymer comprising polyvinyl chloride, a vinyl chloride monomer unit of 80% or more and a vinyl acetate, propylene, styrene, or acrylate ester unit of 20% or less. Post-chlorinated polyvinyl chloride. These may be used alone or in combination of two or more.

The processability improver (B) used in the present invention
Is obtained by adding the monomer mixture (b) in the presence of the latex of the first-stage polymer obtained by emulsion polymerization of the monomer mixture (a), and then polymerizing the two-stage polymer mixture obtained by polymerization. It is a component used for the purpose of improving foaming properties without deteriorating properties such as excellent transparency of the vinyl chloride resin.

The monomer mixture (a) is composed of 50 to 100%, preferably 60 to 90%, more preferably 70 to 85% of methyl methacrylate, which is a mixture of methacrylate and acrylate except methyl methacrylate. 0 to 50%, preferably 10 to 40%, of monomers selected from
More preferably, 15 to 30%, and 0 to 20%, preferably 0 to 10% of a vinyl monomer copolymerizable therewith,
More preferably, it is a mixture consisting of 0 to 5%.

When the proportion of methyl methacrylate in the monomer mixture (a) is less than 50%, the transparency is lowered.
Further, when the amount of the monomer selected from the methacrylate ester and the acrylate ester other than the methyl methacrylate exceeds 50%, the transparency is lowered. Further, when the amount of the vinyl monomer copolymerizable therewith exceeds 20%, the transparency is reduced.

Specific examples of methacrylic acid esters other than methyl methacrylate in the monomer mixture (a) include, for example, alkyl groups such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. Examples thereof include alkyl methacrylate having 2 to 8 carbon atoms. Specific examples of the acrylate include alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. And so on. These methacrylates and acrylates other than methyl methacrylate may be used alone or in combination of two or more.

Specific examples of the vinyl monomer copolymerizable therewith in the monomer mixture (a) include aromatic vinyls such as styrene and α-methylstyrene and unsaturated nitriles such as acrylonitrile. Is raised. These may be used alone or in combination of two or more.

0.1 g of a (co) polymer (first-stage polymer) obtained by emulsion polymerization of the monomer mixture (a) was added in 100 ml.
Is dissolved in chloroform, and the specific viscosity measured at 30 ° C. is not particularly limited.
1.9, more preferably 0.8 to 1.8, further preferably 0.8 to 1.7, and particularly preferably 0.9 to 1.6.
It is. If the specific viscosity exceeds 1.9, the foamability and processability tend to decrease.

The monomer mixture (b) contains 0 to 50%, preferably 20 to 49%, and more preferably 30 to 45% of methyl methacrylate, which is a mixture of methacrylate and acrylate except methyl methacrylate. At least one monomer selected from the group consisting of 50 to 100%, preferably 51 to 80%, more preferably 55 to 70%, and a vinyl monomer copolymerizable therewith with 0 to 20%, preferably It is a mixture comprising 0 to 10%, more preferably 0 to 5%.

The monomer mixture (b) is polymerized in the presence of the first-stage polymer latex, and the (co) polymer from the mixture (b) is provided in the outer layer of the first-stage polymer. When the processability improver is added to the vinyl chloride resin, it can promote gelation and prevent ungelled products.
As a result, viscosity and elasticity can be efficiently imparted to the vinyl chloride resin.

When the proportion of methyl methacrylate in the monomer mixture (b) exceeds 50%, good gelling properties are lost or ungelled matter is easily generated. The same applies to the case where the proportion of at least one monomer selected from methacrylates and acrylates other than the methyl methacrylate is less than 50%. Further, if necessary, a vinyl monomer copolymerizable with these may be used.
%, But can be used in a range as small as possible.

Specific examples of the methacrylic acid ester excluding methyl methacrylate in the monomer mixture (b) include, for example, alkyl groups such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. Examples thereof include alkyl methacrylate having 2 to 8 carbon atoms. Specific examples of the acrylate include alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. And so on. These methacrylates and acrylates other than methyl methacrylate may be used alone or in combination of two or more. Among them, butyl acrylate is preferred because a polymer having a low glass transition temperature can be obtained. Monomer mixture (b)
Specific examples of vinyl monomers copolymerizable therewith include, for example, aromatic vinyls such as styrene and α-methylstyrene, and unsaturated nitriles such as acrylonitrile. These may be used alone or 2
A combination of more than one species may be used.

The ratio of the monomer mixture (a) and the monomer mixture (b) used for producing the processability improver of the present invention is such that the total amount is 100 parts. (A)
50 to 100 parts, preferably 60 to 95 parts, more preferably 65 to 90 parts, 0 to 50 parts of the monomer mixture (b),
Preferably it is 5 to 40 parts, more preferably 10 to 35 parts.

When the amount of the monomer mixture (a), that is, the amount of the first-stage polymer is less than about 50 parts, the gelability of the vinyl chloride resin cannot be sufficiently improved. When the amount of the monomer mixture (b), that is, the (co) polymer formed from the monomer mixture (b) exceeds about 50 parts, the gelling property and the transparency of the vinyl chloride resin composition are reduced. Sex is impaired. The (co) polymer from the monomer mixture (b) is present in the outer layer of the first-stage polymer to specifically improve the gelling property and processability, and as a result, the processability improver of the present invention The effect of addition can be dramatically improved.

The processability improver of the present invention can be produced, for example, by the following method. First, the monomer mixture (a) is emulsion-polymerized in the presence of a suitable medium, an emulsifier, a polymerization initiator, a chain transfer agent and the like, and the monomer mixture (a)
To obtain a first-stage polymer latex. Next, the monomer mixture (b) is sequentially added to the first-stage polymer latex to carry out polymerization. By sequentially polymerizing the respective mixtures in this manner, a two-stage polymer mixture in which the first-stage polymer becomes the inner layer and the (co) polymer from the monomer mixture (b) becomes the outer layer is produced. The dispersion medium used in the emulsion polymerization is usually water.

As the emulsifier, known ones are used. For example, anionic surfactants such as fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonate salts, alkyl phosphate ester salts, and sulfosuccinic acid diester salts, and nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene fatty acid esters. Activators and the like.

As the polymerization initiator, a water-soluble or oil-soluble polymerization initiator is used. For example, ordinary inorganic polymerization initiators such as persulfates, or organic peroxides, azo compounds and the like may be used alone, but these initiator compounds and sulfites, thiosulfates, first metal salts, sodium Combine formaldehyde sulfoxylate and the like,
It may be used in a redox system. Preferred persulfates include, for example, sodium persulfate, potassium persulfate, ammonium persulfate, and the like. Preferred organic peroxides include, for example, t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, Lauroyl peroxide and the like.

The chain transfer agent is not particularly limited. For example, t-dodecyl mercaptan, t-decyl mercaptan, n-dodecyl mercaptan, n-decyl mercaptan and the like can be used. As the specific viscosity, a ratio of a monomer and an initiator or a mercaptan can be used.

The temperature and time during the emulsion polymerization reaction are not particularly limited, and may be suitably adjusted according to the purpose of use so as to obtain desired specific viscosity and particle size.

In adding the monomer mixture (b),
By confirming that the first-stage polymerization is completed and adding it, each stage of polymerization can be carried out without mixing with the first-stage monomer mixture (a).

The latex of the two-stage polymer mixture thus obtained has an average particle diameter of 100 to 3000 °, preferably 100 to 2000 °, and is subjected to salting out, coagulation by addition of a usual electrolyte, spraying in hot air and drying. By doing
Removed from latex. If necessary, washing, dehydration, drying and the like are performed by a usual method.

The resulting two-stage polymer mixture is prepared by dissolving 0.1 g of the polymer in 100 ml of chloroform, and the specific viscosity measured at 30 ° C. is not particularly limited. 7, more preferably 0.6 to 1.6,
More preferably, it is 0.7 to 1.5. If the specific viscosity is more than 1.7, foamability and processability tend to decrease.

The obtained two-stage polymer mixture is usually a white powder having an average particle size of 30 to 300 μm, and is added to a vinyl chloride resin as a processability improver.

The foamable vinyl chloride resin composition of the present invention is produced by mixing the processability improver of the present invention with a vinyl chloride resin according to a conventional method.

The amount of the processability improver to be added is 0.5 to 30 parts, preferably 5 to 25 parts, more preferably 8 to 25 parts based on 100 parts of the vinyl chloride resin.
If the amount of the processability improver is less than 0.5 part, the effect of adding the processability improver will not be sufficiently obtained, and if it exceeds 30 parts, the excellent mechanical properties of the vinyl chloride resin will be impaired.

The method of adding water used as the blowing agent (C) in the present invention to the vinyl chloride resin composition is not particularly limited, but includes vinyl chloride resins, processability improvers, and others. A compounding agent other than water may be gradually added while stirring with a mixer, or may be press-fitted in an extruder. Alternatively, water may be impregnated in advance with the (meth) acrylate copolymer as a processability improver, and the dehydrated slurry of the (meth) acrylate copolymer after the emulsion polymerization is gradually added. The moisture content may be adjusted while drying.

The amount of the water to be added is not particularly limited according to the purpose, but is usually 0.5 to 15 parts, preferably 1 to 100 parts of the vinyl chloride resin.
10 to 10 parts, more preferably 2 to 8 parts. If the amount of water added is less than 0.5 part, a molded article having a sufficient expansion ratio cannot be obtained, and if it exceeds 15 parts, a uniform foamed molded article is difficult to obtain, and shrinkage of the molded article immediately after extrusion molding is reduced. It becomes remarkable. The amount of the water may be varied in accordance with the amount of the processability improver. For example, 100 parts of the vinyl chloride resin and 10 parts of the processability improver in the case of 10 parts of the processability improver are used. It is preferable to add 2 to 15 parts of water in the case of 0.5 to 10 parts, and in the case of 20 parts of the processability improver.

The pyrolytic foaming agent used as the foaming agent (C) in the present invention includes a pyrolytic inorganic foaming agent and a pyrolytic organic foaming agent. Examples of the thermal decomposition type inorganic foaming agent include, for example, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate and the like. Examples of the thermal decomposition type organic foaming agent include nitroso compounds such as N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'dinitrosoterephthalamide, azodicarbonamide, azobis Examples include azo compounds such as isobutyronitrile, and sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide and toluenesulfonyl hydrazide. These can be used alone or in combination of two or more. Among them, sodium bicarbonate and azodicarbonamide are preferable in terms of foaming efficiency and cost.

The amount of the pyrolytic foaming agent to be added is not particularly limited according to the purpose, but is usually 0 to 20 parts, preferably 0 to 20 parts with respect to 100 parts of the vinyl chloride resin. 15 parts, more preferably 0 to 12 parts. If the amount of the pyrolytic foaming agent exceeds 20 parts, it is difficult to obtain a uniform foam molded article. The foamable vinyl chloride resin composition of the present invention may contain, if necessary, other additives such as stabilizers, lubricants, impact resistance enhancers, plasticizers, coloring agents, and fillers alone or in combination of two or more. May be added.
The method for producing the foamable vinyl chloride resin composition of the present invention is not particularly limited. For example, the vinyl chloride resin, the processability improver, the pyrolytic foaming agent, and other additives may be added while being stirred by a mixer or the like, or may be press-fitted in an extruder. In addition, the (meth) acrylate copolymer, which is a processability improver, is impregnated with water, and then mixed with the vinyl chloride resin, the processability improver, the pyrolytic foaming agent, and other additives. Alternatively, the water content may be adjusted while gradually drying the dehydrated cake of the (meth) acrylic acid ester-based copolymer after the emulsion polymerization, followed by mixing.

The molding method of the foamable vinyl chloride resin composition of the present invention is not particularly limited, and a generally used molding method such as an extrusion molding method can be applied.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The evaluation methods used in the examples and comparative examples are summarized below. (Measurement of specific viscosity of first-stage polymer and second-stage polymer mixture (processability improver))
Was dissolved in chloroform, and the measurement was carried out using a Ubelode viscometer kept at a constant temperature in a 30 ° C. water bath. (Measurement of expansion ratio) After measuring the specific gravity of the obtained powder compound (non-foamed molded article of vinyl chloride resin composition), the powder compound was molded by a small single screw extruder attached to Labo Plastmill manufactured by Toyo Seiki Co., Ltd. The specific gravity of the obtained round bar-shaped foamed molded article (foamed molded article of the vinyl chloride resin composition) was measured, and the expansion ratio was calculated by the following formula based on the measured value.

Expansion ratio = (specific gravity of non-expanded molded article of vinyl chloride resin composition) / (specific gravity of expanded molded article of vinyl chloride resin composition) The extruder specifications and molding conditions are shown below.

Extruder specifications Screw: L / D = 20, compression ratio = 2.7, rotation speed =
30 rpm die: diameter = 5 mm, land = 20 mm Molding conditions Molding temperature: C1 = 170 ° C., C2 = 175 ° C., C3 = 1
80 ° C., die = 185 ° C. (Measurement of polymerization conversion) The polymerization conversion was calculated by the following equation.

Polymerization conversion (%) = {amount of polymerization produced / amount of charged monomer} × 100 (measurement of average particle diameter of latex) The obtained latex was subjected to a U-2000 spectrophotometer manufactured by Hitachi, Ltd. Was used to measure the average particle size using light scattering at a wavelength of 546 nm. (Evaluation of Cell Form) The cell form of the obtained molded article was visually observed for appearance and evaluated according to the following criteria.

A: The cell structure is uniform and the appearance is excellent.

Δ: The broken cells are scattered. ×: Most of the cells were crushed and the appearance was bad.

Example 1 0.7 part of dioctyl sodium sulfosuccinate previously dissolved in water was added as an emulsifier to an 8 liter reactor equipped with a stirrer, and the total amount of water was adjusted to 200 parts including the amount of water contained in the auxiliary materials added thereafter. Water was added to make it. After removing oxygen in the space and water by flowing nitrogen through the gas phase and the liquid phase in the reactor, the content was heated to 70 ° C. while stirring. Next, 60 parts of methyl methacrylate (hereinafter, referred to as MMA) was added to the reactor,
A first-stage monomer mixture consisting of 20 parts of butyl acrylate (hereinafter referred to as BA) was added all at once, and then 0.005 part of potassium persulfate was added as an initiator. Was completed. After that, MM
A second-stage monomer mixture composed of 6 parts of A and 14 parts of BA was dropped at a rate of about 30 parts per hour. After completion of the dropwise addition, the content was maintained at 70 ° C. for 90 minutes, and then cooled to obtain a latex, and the average particle diameter was measured. Table 1 shows the results.

At this time, the polymerization conversion rate was 99.5%.
Met. The resulting latex is subjected to salting out and coagulation with an aqueous solution of calcium chloride, heated to 90 ° C. and heat-treated, and then filtered using a centrifugal dehydrator to obtain a dehydrated cake of the obtained two-stage polymer mixture. Was washed with water in the same amount as the weight of the sample, and dried with a parallel flow dryer at 50 ° C. for 15 hours to obtain a white powdery two-stage polymer sample (1).
The specific viscosity of the obtained polymer sample (1) was measured. Table 1 shows the results.

Next, polyvinyl chloride (manufactured by Kanegafuchi Chemical Industry Co., Ltd., Kanevinyl S-1007, average degree of polymerization: 68)
0) In 100 parts, 10.0 parts of the polymer sample (1), 6.0 parts of calcium carbonate, 2.0 parts of titanium oxide, octyltin mercapto-based stabilizer (TVS # 883 manufactured by Nitto Kasei Co., Ltd.)
1) 2.0 parts, calcium stearate 0.6 parts, hydroxystearic acid (manufactured by Henkel, LOXIOL G)
-21) 0.1 part, fatty acid alcohol dibasic ester 0.9 (LOXIOL G-60, manufactured by Henkel)
9 parts and 0.6 parts of polyethylene wax (made by Allied Chemical Co., ACPE-617A) were mixed with a Henschel mixer, heated to an internal temperature of 110 ° C., cooled, and further added with 3.0 parts of water. The mixture was mixed to prepare a powder compound, molded using a small single-screw extruder attached to Labo Plastomill manufactured by Toyo Seiki Co., Ltd., and the cell shape of the obtained round bar-shaped foam molded product was evaluated, and the expansion ratio was measured. Table 1 shows the results.

Examples 2 to 7 and Comparative Examples 1 to 3 Polymer components (2) to (10) were obtained in the same manner as in Example 1 according to the components shown in Table 1 with the components shown in Table 1. Each characteristic value was measured. Further, using the obtained polymer samples (2) to (10), each was blended with polyvinyl chloride in the same manner as in Example 1 to obtain a round bar-shaped foam molded article, and the above evaluation was carried out. 2 to 7 and Comparative Examples 1 to 3. Table 1 shows the results.

[0060]

[Table 1] From the results shown in Table 1, when the polymer samples (1) to (7) were used, a composition having good foaming property was obtained. However, methacrylic acid esters other than methyl methacrylate, acrylic acid esters, and copolymers thereof were used. In the case of using polymer samples (8) to (10) using the monomer mixture (A) equivalent in which the proportion of the polymerizable vinyl monomer was increased beyond the range of the present invention, sufficient A good foaming property cannot be obtained.

Examples 8 to 12 and Comparative Examples 4 to 6 According to the compositions shown in Table 2, polymer samples (11) to (18) were obtained in the same manner as in Example 1. The evaluation was performed using the obtained polymer sample. Table 2 shows the results.

[0062]

[Table 2] From the results in Table 2, when the composition of the monomer mixture (B) is within the range of the present invention as in the polymer samples (11) to (15), a composition having good foamability is obtained. It is understood that it is possible. On the other hand, polymer samples (16) to (18) using equivalents of the monomer mixture (B) whose composition is out of the range of the present invention.
It can be seen that the use of the compound reduces foamability.

Examples 13 to 16 and Comparative Examples 7 and 8 According to the compositions shown in Table 3, polymer samples (19) to (24) were obtained in the same manner as in Example 1.

The above polymer samples were evaluated as described above. Table 3 shows the results.

[0065]

[Table 3] From the results in Table 3, as in the polymer samples (19) to (22), when the amount of the monomer mixture (A) is within the range of the present invention, a composition having good foamability is obtained. It can be seen that it can be obtained. On the other hand, when the polymer samples (23) and (24) in which the amount of the monomer mixture (A) is smaller than the range of the present invention are used, it is understood that the foamability is not sufficient.

Examples 17 to 20 Samples (25) to (28) were obtained in the same manner as in the examples according to the compositions shown in Table 4.

The above polymer samples were evaluated as described above. Table 4 shows the results.

[0068]

[Table 4] Examples 21 to 24 and Comparative Examples 9 and 10 In order to evaluate the difference in the foamability when the number of parts of the polymer sample (28) used in Example 20 was changed into the vinyl chloride resin, the difference in Example 20 was evaluated. Polymer sample used (28)
Is 10.0 parts by weight based on 100 parts of polyvinyl chloride.
Parts instead of 3.0 parts, and instead of 3.0 parts of water as a foaming agent, the same number of parts as shown in Table 5 was used. And foamability were evaluated. Table 5 shows the results. However, in the case of Comparative Example 10, the non-uniformity of the composition was increased, and a molded article suitable for evaluating foamability could not be obtained.

[0069]

[Table 5] From the results in Table 5, the composition in which the polymer sample (28) was blended within the range of the present invention showed good foamability, but as shown in Comparative Example 9, the composition was increased beyond the range of the present invention. It can be seen that when the amount is reduced, sufficient foamability cannot be obtained.

Examples 25 to 28 and Comparative Examples 11 to 14 In order to evaluate the difference in the foaming property when the type of foaming agent and the number of blending parts were changed, the polymer (28) of the polymer sample (28) used in Example 20 was evaluated. A molded article was obtained in the same manner as in Example 20, except that the blending number was set to 10.0 parts with respect to 100 parts of vinyl chloride, and the type and the blending number of the foaming agent were changed as described in Table 6, and the foamability was evaluated. went. Table 6 shows the results.

In the table, SBC is sodium bicarbonate, A
DCA stands for azodicarbonamide.

[0072]

[Table 6] From the results in Table 6, the composition containing water within the range of the present invention has good foaming properties, but reduces the number of blending parts beyond the range of the present invention as in Comparative Examples 11 and 12. It can be seen that sufficient foaming properties cannot be obtained when used in an increased amount. Further, it can be seen that sufficient foaming properties cannot be obtained even when the pyrolytic organic blowing agent is used alone as the blowing agent as in Comparative Examples 13 and 14.

Examples 29 to 32 and Comparative Example 15 In order to evaluate the difference in the foaming property when the type and the number of parts of the pyrolytic foaming agent mixed with water as the blowing agent were evaluated, the results were used in Example 20. Polymer sample (2
8) 1 part of polyvinyl chloride per 100 parts of polyvinyl chloride
A molded product was obtained in the same manner as in Example 20, except that the amount was 0.0 parts, and the type and the number of blending parts of the pyrolytic foaming agent were changed as shown in Table 7, and the foamability was evaluated. Table 7 shows the results.

[0074]

[Table 7] From the results in Table 7, the composition in which the pyrolytic foaming agent was blended within the range of the present invention had good foamability, but as in Comparative Example 15, the number of blended parts exceeded the range of the present invention. It can be seen that sufficient foaming properties cannot be obtained when used in an increased amount.

[0075]

The foamable vinyl chloride resin composition of the present invention uses a vinyl chloride resin, a specific (meth) acrylate copolymer, water or water and a pyrolytic foaming agent. The (meth) acrylate-based copolymer is copolymerized with 50 to 100% by weight of methyl methacrylate and 0 to 50% by weight of a monomer selected from methacrylate and acrylate except methyl methacrylate. In the presence of a (co) polymer latex obtained by emulsion-polymerizing 50 to 100 parts by weight of a monomer mixture (A) comprising 0 to 20% by weight of a possible vinyl monomer, methyl methacrylate 0 50% by weight and at least 50% by weight of at least one monomer selected from methacrylates and acrylates excluding methyl methacrylate and copolymerizable therewith It is a polymer mixture obtained by adding and polymerizing 0 to 50 parts by weight of a monomer mixture (B) consisting of 0 to 20% by weight of a vinyl monomer so that the total amount becomes 100 parts by weight. Since a specific amount of a characteristic (meth) acrylate copolymer within a specific range is used, a foamed molded article having a high magnification of 5 to 15 times or more can be obtained, and the cell The morphology is good.

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Claims (2)

[Claims] (A) 100 parts by weight of a vinyl chloride resin and (B) methyl methacrylate 5 as a processability improver.
From 0 to 100% by weight, from 0 to 50% by weight of a monomer selected from methacrylates and acrylates excluding methyl methacrylate, and from 0 to 20% by weight of a vinyl monomer copolymerizable therewith. Monomer mixture (a)
In the presence of (co) polymer latex obtained by emulsion polymerization of 50-100 parts by weight, methyl methacrylate 0-5
0% by weight, 50 to 100% by weight of at least one monomer selected from methacrylates and acrylates excluding methyl methacrylate, and 0 to 20% by weight of vinyl monomers copolymerizable therewith (Meth) acrylic ester copolymer 5 which is a polymer mixture obtained by adding and polymerizing 0 to 50 parts by weight of a monomer mixture (b) consisting of A foamable vinyl chloride resin composition comprising 30 parts by weight, 0.5 to 15 parts by weight of water as a foaming agent and 0 to 20 parts by weight of a pyrolytic foaming agent. 2. The processability improver (B) comprises 50 to 100% by weight of methyl methacrylate and 0 to 50% by weight of a monomer selected from methacrylates and acrylates excluding methyl methacrylate. Of 100 to 100 parts by weight of a monomer mixture (a) consisting of 0 to 20% by weight of a vinyl monomer copolymerizable with the above, and 0.1 g of the polymer is dissolved in 100 ml of chloroform. In the presence of a latex of (co) polymer having a specific viscosity of 0.7 or more at 30 ° C. of the dissolved solution, 0 to 50% by weight of methyl methacrylate and methacrylate and acrylate except methyl methacrylate A monomer mixture (b) comprising 50 to 100% by weight of at least one monomer selected from the group consisting of 0 to 20% by weight of a vinyl monomer copolymerizable therewith; 0 to 50 parts by weight in a total amount of 10
A polymer mixture obtained by adding and polymerizing so as to be 0 parts by weight has a specific viscosity of 0.5 g at 30 ° C. in a solution obtained by dissolving 0.1 g of the polymer mixture in 100 ml of chloroform.
The foamable vinyl chloride-based resin composition according to claim 1, which is a (meth) acrylate copolymer based on the above.