JP2000327879A - Vinyl chloride-based resin pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinyl chloride-based resin pipe joint excellent in impact resistance, moldability and resistance to pulsation. SOLUTION: The title pipe joint is mainly composed of a vinyl chloride-based resin having a polymerization degree, of its vinyl chloride-derived portion, of 650-1,100 obtained by graft copolymerizing by suspension polymerization 95-90 wt.% of vinyl chloride to 5-10 wt.% of an acrylic copolymer obtained by graft copolymerization of a monomer composition, prepared by mixing a polyfunctional monomer with a (meth)acrylate monomer which gives a homopolymer having a glass transition temperature of at least -55 deg.C, to a copolymer obtained by polymerization of a monomer composition prepared by mixing an alkyl (meth)acrylate monomer, which gives a homopolymer having a glass transition temperature of lower than-60 deg.C, with a polyfunctional monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article of a vinyl chloride resin which is excellent in impact resistance, moldability, pulsation resistance and heat resistance.

[0002]

2. Description of the Related Art Vinyl chloride resin is a material excellent in mechanical strength, weather resistance, chemical resistance and the like, and is therefore widely used for building members, pipework equipment, housing materials and the like. However, since vinyl chloride resin has poor impact resistance, it has a disadvantage that the impact resistance is particularly poor at low temperatures. Accordingly, cracking due to impact becomes a problem particularly when used in pipe joints and the like that are expected to be used at low temperatures. Therefore,
Conventionally, various reforming methods have been proposed.

[0003] For example, as a method for improving impact resistance, chlorinated polyethylene (CP)
E), a method in which a rubber-based resin such as methyl methacrylate-butadiene-styrene copolymer (MBS) or acrylic rubber is blended as an impact-resistant reinforcing agent, and then molded.

However, when tensile stress is repeatedly applied to a molded article of a vinyl chloride resin composition containing a rubber resin as an impact resistance enhancer, fatigue fracture is likely to occur from the vicinity of rubber particles dispersed in the vinyl chloride resin. There was a disadvantage. Therefore, a vinyl chloride resin pipe joint obtained by molding a vinyl chloride resin composition containing a rubber resin,
For example, when used for water supply piping, there is a problem that pulsation water pressure easily causes fatigue failure even when the pressure is equal to or lower than the breaking water pressure, resulting in poor pulsation resistance.

There are several methods for improving pulsation resistance. For example, it is known that pulsation resistance is improved by increasing the degree of polymerization of vinyl chloride. However, when the degree of polymerization of vinyl chloride is increased, the melt viscosity of the vinyl chloride resin is significantly increased, and there is a problem that it is difficult to obtain a product by a general molding method such as injection molding.

[0006] Further, in the vinyl chloride resin composition containing a rubber resin as an impact resistance enhancer, there is a problem that the heat resistance decreases with the addition of the rubber resin. In particular,
When a rubber-based resin is added to sufficiently exhibit impact resistance at a low temperature near the freezing point, heat resistance is significantly reduced,
For example, there is a problem that a molded article is thermally deformed during transportation under direct sunlight. On the other hand, as a method of increasing the heat resistance, a method of using a chlorinated vinyl chloride resin obtained by post-chlorinating a vinyl chloride resin, or a method of adding a heat resistance improver can be considered. ,
There is a problem that impact resistance is reduced.

Japanese Patent Application Laid-Open No. 9-3291 discloses a vinyl chloride resin pipe joint using a resin obtained by grafting a vinyl chloride resin to an acrylic copolymer. Although it is excellent in heat resistance and heat resistance, it is inferior in impact resistance at a low temperature near the freezing point, and it is difficult to use it as it is for water pipes.

As described above, it has been very difficult to obtain a vinyl chloride resin pipe joint excellent in impact resistance, moldability, pulsation resistance and heat resistance.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vinyl chloride resin pipe joint which is excellent in impact resistance, moldability and pulsation resistance in view of the above-mentioned drawbacks. .

Another object of the present invention is to provide a vinyl chloride resin pipe joint having excellent low-temperature impact resistance and heat resistance.

[0011]

Means for Solving the Problems The present inventors have conducted detailed studies on a vinyl chloride resin pipe joint which is excellent in impact resistance, moldability and pulsation resistance. A copolymer obtained by polymerizing a monomer composition obtained by mixing a polyfunctional monomer with an alkyl (meth) acrylate monomer having a glass transition temperature of less than −60 ° C. has a homopolymer having a glass transition temperature of −55 ° C. 5 to 10% by weight of acrylic copolymer obtained by graft copolymerizing a monomer composition obtained by mixing a polyfunctional monomer with the above (meth) acrylate monomer
By using a vinyl chloride resin having a degree of polymerization of 650 to 1,100 as a main component, which is obtained by graft copolymerizing 95 to 90% by weight of vinyl chloride by suspension polymerization, It has been found that the above disadvantages can be overcome.

Further, the present inventors have conducted detailed studies on vinyl chloride resin pipe joints having excellent impact resistance and heat resistance at low temperatures, and as a result, have found that the glass transition temperature of the homopolymer is less than -60 ° C. A copolymer obtained by polymerizing a monomer composition obtained by mixing a polyfunctional monomer with an alkyl (meth) acrylate monomer has a homopolymer with a (meth) acrylate monomer having a glass transition temperature of -55 ° C or higher. Graft copolymerization of 95 to 88% by weight of vinyl chloride with 5 to 12% by weight of an acrylic copolymer obtained by graft copolymerizing a monomer composition obtained by mixing functional monomers. Impact resistance at low temperature by using as a main component a vinyl chloride resin having a degree of polymerization of a vinyl chloride portion of 650 to 1,100 obtained by It found that may increase the fine heat resistance.

Hereinafter, the invention of a vinyl chloride resin pipe joint excellent in impact resistance, moldability and pulsation resistance will be referred to as a first invention, and a vinyl chloride resin pipe joint excellent in impact resistance and heat resistance at low temperatures. The second invention is defined as the second invention.
When the second invention is collectively referred to, it is the present invention.

Hereinafter, the present invention will be described in detail.

Among the monomers used in the present invention, an alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than -60 ° C. has a main component of a central portion (hereinafter referred to as a core portion) of an acrylic copolymer. None, added for the purpose of developing low-temperature impact resistance of vinyl chloride resin. In order to have sufficient rubber elasticity even near the freezing point, the glass transition temperature of the homopolymer needs to be less than -60 ° C. Examples of such a monomer include n-heptyl acrylate, n-octyl acrylate, 2-methylheptyl acrylate,
Examples include ethylhexyl acrylate, n-nonyl acrylate, 2-methyloctyl acrylate, 2-ethylheptyl acrylate, n-decyl acrylate, 2-methylnonyl acrylate, and 2-ethyloctyl acrylate. These may be used alone,
More than one type may be used in combination.

The above homopolymer has a glass transition temperature of -6.
For the purpose of further improving the low-temperature impact resistance of a vinyl chloride resin, a polymerizable monomer having a glass transition temperature of a homopolymer of less than -60 ° C may be added to an alkyl (meth) acrylate having a temperature of less than 0 ° C. For example, dienes such as butadiene and isoprene, alkenes such as ethylene and 1-octene, n-pentyl vinyl ether, n
-Vinyl ethers such as hexyl vinyl ether and silicons such as dimethylsiloxane.

The glass transition temperature of the alkyl (meth) acrylate monomer and the polymerizable monomer having a glass transition temperature of the above homopolymer of less than -60 ° C. is described in “Polymer Data Handbook (Basic Edition)”, published by Baifukan, edited by The Society of Polymer Science, Japan. And so on.

Further, among the monomers used in the present invention, the (meth) acrylate monomer having a glass transition temperature of a homopolymer of -55 ° C. or higher is the outer shell (hereinafter referred to as shell) of the acrylic copolymer. It is the main component and is added for the purpose of coating the core and reducing the adhesiveness of the acrylic copolymer and at the same time maintaining its shape.The acrylic copolymer retains its shape against external forces such as pulsating water pressure. In order to achieve this, the shell portion is required to have sufficient rigidity, so that the glass transition temperature of the homopolymer needs to be −55 ° C. or higher. Such monomers include, for example, methyl acrylate, ethyl (meth) acrylate, n-
Propyl (meth) acrylate, isopropyl (meth)
Acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl acrylate, cumyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate , N-heptyl methacrylate, n-octyl methacrylate, 2
-Methylheptyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, 2-methyloctyl methacrylate, 2-ethylheptyl methacrylate, n-decyl methacrylate, 2-methylnonyl methacrylate, 2-ethyloctyl methacrylate, lauryl (meth) acrylate, Myristyl (meth) acrylate, palmityl (meth) acrylate,
Alkyl (meth) such as stearyl (meth) acrylate
Acrylate, 2-hydroxyethyl acrylate, 2
-Hydroxypropyl (meth) acrylate and the like. These may be used alone or in combination of two or more.

Further, the (meth) acrylate monomer having a glass transition temperature of -55 ° C. or higher of the above homopolymer includes:
For the purpose of improving mechanical strength, weather resistance, chemical resistance, transparency, and pulsation resistance of the vinyl chloride resin, a polymerizable monomer having a glass transition temperature of a homopolymer of −55 ° C. or higher may be added, Examples include aromatic vinyl monomers such as styrene and α-methylstyrene, unsaturated nitriles such as acrylonitrile and methacrylonitrile, and vinyl esters such as vinyl acetate and vinyl propionate.

The glass transition temperature of the alkyl (meth) acrylate monomer and the polymerizable monomer having a glass transition temperature of the homopolymer of -55 ° C. or higher is determined by the Polymer Data Handbook (Basic Edition), published by Baifukan, edited by The Society of Polymer Science, Japan. And so on.

An alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than -60.degree. C. and a (meth) acrylate monomer having a glass transition temperature of a homopolymer of -55.degree. C. or more, which are used in the acrylic copolymer. The weight ratio is not particularly limited, but 20 to 90% by weight of an alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than -60 ° C and 80 to 10% by weight of a monomer having a glass transition temperature of a homopolymer of -55 ° C or more. % Is desirable. If the homopolymer has an alkyl (meth) acrylate monomer having a glass transition temperature of less than −60 ° C. and less than 20% by weight, it may be difficult to obtain impact resistance, and if it exceeds 90% by weight, the appearance of a molded article is deteriorated. This is because there are cases where More preferably, the homopolymer has 40 to 80% by weight of an alkyl (meth) acrylate monomer having a glass transition temperature of less than -60C, and the homopolymer has a glass transition temperature of 60 to 20% by weight of a monomer having a glass transition temperature of -55C or more.

The above-mentioned polyfunctional monomer not only improves the impact resistance of the vinyl chloride resin by crosslinking the polymer in the core, but also reduces the adhesiveness of the acrylic copolymer by crosslinking the polymer in the shell. It is added for the purpose of maintaining the shape and assisting the graft reaction between the acrylic copolymer and the vinyl chloride resin and improving the impact resistance. For example,
Di (meth) such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and trimethylolpropane di (meth) acrylate Acrylates; tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate;
Diallyl compounds and triallyl compounds such as pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, diallyl phthalate, diallyl maleate, diallyl fumarate, diallyl succinate, triallyl isocyanurate; divinylbenzene, butadiene, etc. And divinyl compounds. These may be used alone or in combination of two or more.

The acrylic copolymer used in the present invention polymerizes a monomer composition obtained by mixing a polyfunctional monomer with an alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than -60 ° C. And a monomer composition obtained by mixing a polyfunctional monomer with a (meth) acrylate monomer having a glass transition temperature of −55 ° C. or higher and a core portion composed of a copolymer obtained by the above-mentioned method. It is characterized by having a core-shell type double structure formed from a shell portion formed by the above-described process.

The method for obtaining the acrylic copolymer is not particularly limited, and examples thereof include an emulsion polymerization method and a suspension polymerization method. Considering the impact resistance, the emulsion polymerization method is preferred.

In the present invention, when the above-mentioned acrylic copolymer particles are synthesized mainly by emulsion polymerization, first, a polyfunctional monomer is mixed with an alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than -60 ° C. Forming a core portion by polymerizing the resulting monomer composition, and mixing a polyfunctional monomer with a (meth) acrylate monomer having a glass transition temperature of −55 ° C. or higher in the presence of the core polymer. A shell portion is synthesized by adding and polymerizing a monomer composition to form a core-shell double structure.

In the emulsion polymerization method, an emulsifying dispersant is added for the purpose of improving the dispersion stability of the above-mentioned acrylic mixed monomer in an emulsion and efficiently performing polymerization. The emulsifying and dispersing agent is not particularly limited. For example, anionic surfactants such as polyoxyethylene nonylphenyl ether sulfate (trade name “Hitenol N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); Nonionic surfactants Agents; partially saponified polyvinyl alcohol; cellulosic dispersants; gelatin and the like.

In the emulsion polymerization method, a polymerization initiator is used. The polymerization initiator is not particularly limited, for example,
Water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate and aqueous hydrogen peroxide; organic peroxides such as benzoyl peroxide and lauroyl peroxide; and azo initiators such as azobisisobutyronitrile. Further, if necessary, a pH adjuster, an antioxidant, and the like may be added.

The emulsion polymerization method is not particularly limited.
From the difference in the method of adding the monomer, for example, a batch polymerization method,
Examples include a monomer dropping method and an emulsion dropping method.
The batch polymerization method is, for example, in a jacketed polymerization reactor,
Pure water, an emulsifying dispersant, a polymerization initiator, a mixed monomer composed of the acrylic mixed monomer and the polyfunctional monomer are added all at once, and the mixture is sufficiently emulsified by stirring under the conditions of oxygen removal and pressurization by a nitrogen gas flow. After that, polymerization is performed by heating the inside of the vessel with a jacket.

In the monomer dropping method, for example, pure water, an emulsifying dispersant, and a polymerization initiator are placed in a jacketed polymerization reactor,
Under the conditions of oxygen removal and pressurization under a nitrogen stream,
First, after the inside of the vessel is heated by a jacket, the above-mentioned mixed monomer is dropped by a predetermined amount to gradually polymerize.

In the emulsion dropping method, for example, an emulsified monomer is prepared in advance by sufficiently emulsifying the above-mentioned mixed monomer, emulsifying dispersant, and pure water with stirring, and then pure water and a polymerization initiator are introduced into a jacketed polymerization reactor. In this method, the vessel is first heated by a jacket under the conditions of oxygen removal and pressurization under a nitrogen stream, and then the above-mentioned emulsified monomer is dropped by a predetermined amount to carry out polymerization.

In the present invention, a vinyl chloride resin is obtained by using the acrylic copolymer obtained by the above method and graft-copolymerizing vinyl chloride to the acrylic copolymer by suspension polymerization. obtain.

The method for obtaining the vinyl chloride resin is not particularly limited, and examples thereof include an emulsion polymerization method and a suspension polymerization method. Among them, the suspension polymerization method is preferred. In the suspension polymerization method, a dispersant and an oil-soluble polymerization initiator are used for the purpose of improving the dispersion stability of the acrylic copolymer and efficiently performing the graft copolymerization of vinyl chloride.

The dispersant is not particularly limited.
Examples include methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, polyvinyl alcohol, partially saponified polyvinyl acetate, gelatin, polyvinylpyrrolidone, and starch maleic anhydride-styrene copolymer. These may be used alone or in combination of two or more.

As the oil-soluble polymerization initiator, a radical polymerization initiator is preferably used from the viewpoint of being advantageous for graft copolymerization. The radical polymerization initiator is not particularly limited and includes, for example, lauroyl peroxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, t-butyl peroxy neodecanoate, α-cumene Organic peroxides such as luperoxy neodecanoate; 2,2-azobisisobutyronitrile, 2,2-azobis-2,4
-Azo compounds such as dimethylvaleronitrile. In the above suspension polymerization method, a pH adjuster, an antioxidant and the like may be added as necessary.

Specifically, for example, pure water, the acrylic copolymer, a dispersant, an oil-soluble polymerization initiator, and, if necessary,
A polymerization regulator is charged, and then the air in the polymerization vessel is discharged by a vacuum pump, and further, under stirring conditions, vinyl chloride, and
If necessary, after adding another vinyl monomer, the inside of the reaction vessel is heated by a jacket to carry out graft copolymerization of vinyl chloride.

Since the graft copolymerization of vinyl chloride is an exothermic reaction, the temperature in the reaction vessel can be controlled by changing the jacket temperature. After completion of the reaction, unreacted vinyl chloride is removed to form a slurry, and the slurry is dehydrated and dried to produce a vinyl chloride resin.

In the first invention, the content of the acrylic copolymer in the vinyl chloride resin is limited to 5 to 10% by weight. If it is less than 5% by weight, sufficient impact resistance cannot be obtained, and if it exceeds 10% by weight, the pulsation resistance is reduced, so that it is limited to the above range. Preferably it is 6 to 9% by weight.

The content of the acrylic copolymer in the vinyl chloride resin in the second invention of the present application is limited to 5 to 12% by weight. If the content is less than 5% by weight, sufficient impact resistance cannot be obtained, and if it exceeds 12% by weight, the heat resistance is reduced. Therefore, the content is limited to the above range, and preferably in the range of 6 to 10% by weight.

In the present invention, the polymerization degree of the vinyl chloride moiety in the vinyl chloride resin is limited to 650 to 1,100. If the degree of polymerization is less than 650, the mechanical strength and pulsation resistance decrease, and if it exceeds 1,100, the melt viscosity increases and molding becomes difficult. Preferably it is 700-1,000.

The vinyl chloride resin produced by the above production method is obtained by graft copolymerization of vinyl chloride with an acrylic copolymer, so that a molded article of vinyl chloride resin having excellent impact resistance is formed. be able to.

The Izod impact strength at 0 ° C. of the notched test piece according to JIS K 7110 of the vinyl chloride resin molded article according to any one of claims 1 to 3 is 10%.
kg · cm / cm ² or more. 10kg ・ cm
If it is less than / cm ² , the impact resistance of the impact-resistant vinyl chloride resin pipe joint is insufficient, and it cannot be suitably used. It is preferably at least 15 kg · cm / cm ² .

The measurement temperature 23 ° C. vinyl resin pipe joint chloride in the invention of claim 1, pulse frequency 1 Hz,耐脈dynamic test under the conditions of pulsating water pressure ^{0kg · f / cm 2 ~10kg ·} f / cm 2 The number of pulsations required for destruction is limited to 500,000 or more. 500,000
If the number of times is less than the number of times, it cannot be suitably used in applications requiring pulsation resistance, such as a water distribution branch pipe.

The measurement temperature 23 ° C. vinyl resin pipe joint chloride in the invention of claim 2, pulse frequency 1 Hz,耐脈dynamic test under the conditions of pulsating water pressure ^{0kg · f / cm 2 ~10kg ·} f / cm 2 The number of pulsations required for destruction is limited to 750,000 or more. 750,000
If the number is less than the number of times, it cannot be suitably used in applications requiring more pulsation resistance, such as a water supply main line of a water supply system.

The measurement temperature 23 ° C. vinyl resin pipe joint chloride in the invention of claim 3, pulsating frequency 1 Hz,耐脈dynamic test under the conditions of pulsating water pressure ^{0kg · f / cm 2 ~10kg ·} f / cm 2 The number of pulsations required for destruction is limited to 1,000,000 times or more. 1,00
If it is less than 000 times, it cannot be suitably used particularly for applications requiring pulsation resistance, such as water supply piping in buildings. The pulsation resistance test is a test for measuring the number of repetitions required until breakage when a predetermined internal water pressure is repeatedly applied to a pipe joint at a constant frequency.

According to the fifth aspect of the present invention, the notched test piece according to JIS K 7110 of a vinyl chloride resin pipe joint has an Izod impact strength at 0 ° C. of 10 kg ·
cm / cm ² or more. 10kg ・ cm / cm
^When it is less than ² , the impact resistance of the vinyl chloride resin pipe joint at low temperatures is insufficient. Preferably, the Izod impact strength is 15 kg · cm / cm ² or more.

Further, in the invention according to claim 5, the Vicat softening point of the above-mentioned vinyl chloride resin pipe joint at a load of 5 kgf in accordance with JIS K7206 is limited to 78 ° C. or higher. If the temperature is lower than 78 ° C., the molded article may be deformed during transportation or construction under direct sunlight. Preferably, the Vicat softening point is 80 ° C. or higher.

The vinyl chloride resin molded article of the present invention may contain, if necessary, a heat stabilizer, a lubricant, a processing aid, an inorganic filler,
A plasticizer, an antioxidant, an antistatic agent, a heat resistance improver, a pigment and the like may be added.

The heat stabilizer is not particularly restricted but includes, for example, dibutyltin mercapto, dioctyltin mercapto,
Organotin stabilizers such as dimethyltin mercapto, dibutyltin malate, dibutyltin malate polymer, dioctyltin malate, dioctyltin malate polymer, dibutyltin laurate, dibutyltin laurate polymer; lead stearate, dibasic phosphorous acid Lead-based stabilizers such as lead and tribasic lead sulfate; calcium-zinc-based stabilizers; barium-zinc-based stabilizers; and barium-cadmium-based stabilizers.
These may be used alone or in combination of two or more.

The method for mixing the above-mentioned additives with the above-mentioned vinyl chloride resin is not particularly limited, and examples thereof include a method using hot blending and a method using cold blending. The method for molding the vinyl chloride resin pipe joint of the present invention is not particularly limited, but is generally molded by an injection molding method.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. According to the polymerization recipes shown in Tables 1 to 3, an acrylic copolymer and a vinyl chloride resin were obtained by the following operation procedure.

<Preparation of Acrylic Copolymer> (Examples 1 to 7, Comparative Examples 1 to 6) First, a predetermined amount of ion-exchanged water and an emulsifying dispersant (Hytenol N-08 (hereinafter A
S), manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), an alkyl (meth) acrylate monomer having a glass transition temperature of a homopolymer of less than −60 ° C. (hereinafter referred to as a core monomer)
Ethylhexyl acrylate (hereinafter, referred to as 2-EHA) and a polyfunctional monomer (trimethylolpropane triacrylate (hereinafter, referred to as TMPTA)) were mixed and stirred to prepare an emulsifying monomer for a core. Separately, a predetermined amount of ion-exchanged water, an emulsifying dispersant (AS), and an alkyl (meth) having a homopolymer having a glass transition temperature of −60 ° C. or higher.
Acrylate monomer (hereinafter referred to as shell monomer)
Was mixed with n-butyl acrylate (hereinafter referred to as n-BA) and a polyfunctional monomer (TMPTA), and stirred to prepare an emulsion monomer for shell. On the other hand, a predetermined amount of ion-exchanged water was put into a polymerization vessel equipped with a stirrer and a reflux condenser, stirring was started, the pressure inside the polymerization vessel was reduced, and the vessel was deoxygenated. And the polymerization vessel was heated to 70 ° C. Ammonium persulfate (hereinafter, referred to as APS) and 20% by weight of the core emulsifying monomer were added at once as a seed monomer to the polymerization vessel in which the temperature was raised, and polymerization was started. Next, the remainder of the core emulsifying monomer was added dropwise. Next, the emulsifying monomer for shell was dropped, and the dropping of all emulsifying monomers was completed in 3 hours. Thereafter, after an aging period of 1 hour, the polymerization was terminated to obtain an acrylic copolymer latex (hereinafter referred to as latex) having a solid content of about 30% by weight.

Comparative Examples 7 and 8 A predetermined amount of ion-exchanged water, emulsifying dispersant (AS), APS, alkyl (meth) acrylate monomer (n-BA) was added to a polymerization vessel equipped with a stirrer and a reflux condenser. After the polyfunctional monomer (TMPTA) was charged and the oxygen in the vessel was replaced with nitrogen, the reaction vessel was heated to 65 ° C. under stirring conditions, and heated and stirred for 5 hours to obtain a solid content of about 30% by weight. Latex was obtained.

<Preparation of Vinyl Chloride Resin> In a reaction vessel equipped with a stirrer and a jacket, ion-exchanged water, the above latex, and a 3% aqueous solution of partially saponified polyvinyl alcohol (Kuraray Popal L-8, manufactured by Kuraray Co., Ltd.) were added. Abbreviated), 3% aqueous solution of hydroxypropylmethylcellulose (Metroze 60SH50, manufactured by Shin-Etsu Chemical Co., Ltd.) (hereinafter, referred to as MPS), t-butylperoxy neodecanoate (hereinafter, referred to as BPOND), α-cumylperoxy Neodecanoate (hereinafter referred to as QPOND) is charged all at once, then the air in the polymerization vessel is discharged by a vacuum pump, and vinyl chloride is charged under stirring conditions.
By stirring for 0 minute, vinyl chloride was uniformly mixed, and polymerization was started at a predetermined polymerization temperature by controlling the jacket temperature. The completion of the reaction is confirmed by the pressure in the reactor dropping to a predetermined pressure, and the defoaming agent (Toray Silicon SH551) is used.
0, manufactured by Toray Industries, Inc.), and the reaction was stopped. Thereafter, unreacted vinyl chloride was removed, and further dehydration drying was performed to obtain a vinyl chloride resin.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

<Addition of Ingredients> (Examples 1 to 7, Comparative Examples 1 to 8) As shown in Tables 4 and 5, an organic tin-based stabilizer was added to 100 parts by weight of the obtained vinyl chloride-based resin. (Product name "ON" manufactured by Sankyokiseisei
Z-6F ") 1 part by weight, lubricant (manufactured by Riken Vitamin Co., trade name" OPL-01 ") 0.8 part by weight, lubricant (manufactured by NOF Corporation, trade name" Monogly MB ") 0.4 part by weight, A lubricant (manufactured by Mitsui Chemicals, Inc., trade name "Hiwax 2203A") was stirred and mixed with a super mixer (100 L, manufactured by Kawata) to obtain a vinyl chloride resin composition.

(Comparative Examples 9 to 14) A predetermined amount of an impact modifier (CPE: manufactured by Tokuyama Sekisui Co., Ltd., manufactured by Tokuyama Sekisui Co., Ltd.) in a vinyl chloride resin having a degree of polymerization of 800 (trade name "TS800E" manufactured by Tokuyama Sekisui Co., Ltd.) (Esmic CE, MBS: Kane-Ace Chemical Co., Ltd., trade name "Kane-Ace B56", acrylic rubber: Kane-buchi Chemical Co., Ltd., trade name "Kane-Ace FM") and the above stabilizers and lubricants were mixed with a super mixer. Thus, a vinyl chloride resin composition was obtained.

<Molding of pipe joint> The obtained vinyl chloride resin composition was kneaded with a roll kneader at 180 ° C. for 3 minutes to prepare a roll sheet, pelletized using a square-cut pelletizer, and then injection-molded. Machine (made by Toshiba Machine Co., Ltd., product name "IS
350E ") to obtain an elbow-shaped rigid vinyl chloride resin pipe joint having a nominal diameter of 75 mm under the condition of a nozzle temperature of 180 ° C.

<Evaluation of Physical Properties of Vinyl Chloride Resin Molded Article> Physical properties of a vinyl chloride resin molded article were evaluated by the following methods. The results are summarized in Tables 4 to 9.

Shock resistance A rigid polyvinyl chloride resin pipe joint was cut and manufactured in accordance with JIS K 7110. An Izod impact test at 0 ° C. was performed on the notched test piece. The unit is kg · cm / cm ² .

Pulsation resistance A pulsation frequency of 1 Hz and a pulsation water pressure of 0 kg / cm ² to 10 were applied to the above vinyl chloride resin pipe joint in a constant temperature water bath at 23 ° C.
Pulsating water pressure was applied under the condition of kg / cm ^{2, and} the number of repetitions required until breaking was measured at n = 2. Tables 4 to 6 show average values.

Moldability The appearance of the molded article was visually judged, and a level having no practical problem was evaluated as ○, and a level which was not practical was evaluated as ×.

Heat resistance According to JIS K 7206, 5 kg for a test piece cut from the above vinyl chloride resin pipe joint.
The Vicat softening point was measured at f load.

[0065]

[Table 4]

[0066]

[Table 5]

[0067]

[Table 6]

As is clear from the results shown in Tables 4 to 6, the vinyl chloride resin pipe joints of Examples 1 to 4 according to the first invention show good impact resistance, pulsation resistance and molding. It can be seen that the properties are also excellent.

[0069]

[Table 7]

[0070]

[Table 8]

[0071]

[Table 9]

As is clear from the results shown in Tables 7 to 9, the vinyl chloride resin pipe joints of Examples 1 to 3, 5 to 7 according to the second invention were compared with Comparative Examples 3 to 5, 7, 8, 12-14
It can be seen that, compared to the vinyl chloride resin pipe joint of the above, it shows good impact resistance at low temperature and also has excellent heat resistance.

[0073]

The vinyl chloride resin pipe joint of the first invention uses a vinyl chloride resin obtained by graft-polymerizing vinyl chloride to an acrylic copolymer, and has excellent impact resistance and moldability. Excellent pulsation resistance. Therefore, it can be suitably used for applications that require both impact resistance and pulsation resistance, such as water supply applications.

The vinyl chloride resin pipe joint according to the second invention uses a vinyl chloride resin obtained by graft-polymerizing vinyl chloride at the above-mentioned specific ratio with the above-mentioned acrylic copolymer. It has excellent impact resistance and heat resistance. Therefore, it can be suitably used for applications requiring both impact resistance and heat resistance at low temperatures, such as water and sewage applications.

Claims (6)

[Claims] 1. A notched specimen according to JIS K 7110 has an Izod impact strength at 0 ° C. of 10 kg ·
cm / cm ² or more, measurement temperature 23 ° C., pulsation frequency 1 Hz, pulsation water pressure 0 kg · f / cm ² -10 kg
-A polyvinyl chloride resin pipe joint characterized in that the number of pulsations required for breaking in a pulsation resistance test under the condition of f / cm < ² > is 500,000 or more. 2. A notched specimen according to JIS K 7110 has an Izod impact strength at 0 ° C. of 10 kg ·
cm / cm ² or more, measurement temperature 23 ° C., pulsation frequency 1 Hz, pulsation water pressure 0 kg · f / cm ² -10 kg
-A polyvinyl chloride resin pipe joint characterized in that the number of pulsations required for breaking in a pulsation resistance test under the condition of f / cm < ² > is 750,000 times or more. 3. A notched specimen according to JIS K 7110 has an Izod impact strength at 0 ° C. of 10 kg ·
cm / cm ² or more, measurement temperature 23 ° C., pulsation frequency 1 Hz, pulsation water pressure 0 kg · f / cm ² -10 kg
-A polyvinyl chloride resin pipe joint, wherein the number of pulsations required for breaking in a pulsation resistance test under the condition of f / cm < ² > is 1,000,000 or more. 4. The glass transition temperature of the homopolymer is -60.
A copolymer obtained by polymerizing a monomer composition obtained by mixing a polyfunctional monomer with an alkyl (meth) acrylate monomer having a temperature of less than 0 ° C has a (meth) acrylate having a glass transition temperature of a homopolymer of -55 ° C or more. Graft copolymerization of 95 to 90% by weight of vinyl chloride with 5 to 10% by weight of an acrylic copolymer obtained by graft copolymerization of a monomer composition obtained by mixing a monomer with a polyfunctional monomer. Obtained by polymerizing,
A vinyl chloride resin pipe joint comprising a vinyl chloride resin having a polymerization degree of a vinyl chloride portion of 650 to 1,100 as a main component. 5. A test piece with a notch according to JIS K 7110 having an Izod impact strength at 0 ° C. of 10 kg ·
cm / cm ² or more, and the Vicat softening point under a 5 kgf load according to JIS K7206 is 78 ° C.
A vinyl chloride resin pipe joint characterized by the above. 6. The homopolymer has a glass transition temperature of -60.
A copolymer obtained by polymerizing a monomer composition obtained by mixing a polyfunctional monomer with an alkyl (meth) acrylate monomer having a temperature of less than 0 ° C has a (meth) acrylate having a glass transition temperature of a homopolymer of -55 ° C or more. To 5 to 12% by weight of an acrylic copolymer obtained by graft copolymerization of a monomer composition obtained by mixing a monomer with a polyfunctional monomer, 95 to 88% by weight of vinyl chloride is graft copolymerized by suspension polymerization. Obtained by polymerizing,
A vinyl chloride resin pipe joint comprising a vinyl chloride resin having a polymerization degree of a vinyl chloride portion of 650 to 1,100 as a main component.