JPH09263673A - Pipe or joint excellent in flexibility and impact resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe or a joint, formed from a composition, containing a specific alkyl (meth)acrylate in a specific proportion or above, comprising a specified vinyl chloride-based resin and an acrylic processing aid and having flexibility and impact resistance at low temperatures. SOLUTION: This pipe or joint is formed of a resin composition, containing (A) >=50wt.% alkyl (meth)acrylate having <-20 deg.C second order transition temperature of a homopolymer and comprising (B) 100 pts.wt. vinyl chloride- based resin prepared by carrying out the graft copolymerization of (ii) 70-40wt.% vinyl chloride onto (i) 30-60wt.% partially cross-linked acrylic copolymer and (C) 0.5-7 pts.wt. acrylic processing aid. Furthermore, the pipe is obtained by carrying out the extrusion molding of the composition and the joint is prepared by performing the injection molding thereof.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pipe or joint having excellent flexibility and impact resistance.

[0002]

2. Description of the Related Art Conventionally, pipes and joints made mainly of vinyl chloride resin have been widely known as pipeline materials because of their excellent strength, weather resistance and chemical resistance. However, since it has drawbacks in flexibility and impact resistance at low temperatures, it cannot be used for applications such as pipelines requiring earthquake resistance and cold resistance.

As a method for imparting flexibility to vinyl chloride resins, for example, JP-A-49-74727 discloses a method of blending a plasticizer. However,
This method has a problem that sufficient impact resistance cannot be obtained at low temperatures. Further, as a method for imparting impact resistance to a vinyl chloride resin, for example, JP-A-60-1
No. 61449 discloses a composition obtained by blending a vinyl chloride resin with a specific acrylic rubber. However, the pipe or joint obtained by using this composition lacked both flexibility and impact resistance, and could not be used for earthquake-resistant pipes and cold-resistant pipes.

[0004]

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide flexibility and resistance to moderate impact and sufficient impact resistance even at low temperature. It is to provide a pipe or a joint excellent in impact resistance.

[0006]

The pipe or joint excellent in flexibility and impact resistance of the present invention contains 50% by weight of an alkyl (meth) acrylate having a homopolymer having a second-order transition degree of less than -20 ° C. % Or more, and is formed from a resin composition comprising a vinyl chloride resin obtained by graft-polymerizing vinyl chloride on a partially crosslinked acrylic copolymer and a resin composition comprising an acrylic processing aid. is there.

The resin composition used in the present invention comprises a vinyl chloride resin and an acrylic processing aid. The vinyl chloride resin contains 50% by weight or more of an alkyl (meth) acrylate having a degree of secondary transfer of a homopolymer of less than -20 ° C, and vinyl chloride is graft-polymerized on a partially crosslinked acrylic copolymer. It was made.

Examples of the alkyl (meth) acrylate whose second-order transition degree of the above homopolymer is less than -20 ° C include, for example, methyl (meth) acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl (meth) acrylate, n. -Butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate,
Alkyl (meth) acrylates such as t-butyl (meth) acrylate, n-hexyl methacrylate, cyclohexyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-acryloyloxyethyl phthalate Polar group-containing acrylates such as acids; aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene; unsaturated nitriles such as acrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate. They may be used or two or more kinds may be used in combination.

Alkyl (meth) in which the degree of second-order transition of the homopolymer in the acrylic copolymer is less than -20 ° C
If the proportion of acrylate is too small, sufficient impact resistance cannot be imparted to the molded product, so it is limited to 50% by weight or more, preferably 80 to 100% by weight.

The acrylic copolymer is partially crosslinked. This partial cross-linking can be obtained, for example, by copolymerizing with a polyfunctional monomer copolymerizable with the above-mentioned alkyl (meth) acrylate.

As the polyfunctional monomer copolymerizable with the above-mentioned alkyl (meth) acrylate, conventionally known ones can be used, and examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and 1,6- Hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate,
Polyfunctional acrylates such as trimethylolpropane tri (meth) acrylate; polyfunctional allyl compounds such as diallyl phthalate, diallyl malate and triallyl isocyanurate; unsaturated compounds such as butadiene, etc., and these are used alone. Alternatively, two or more kinds may be used in combination.

The amount of the polyfunctional monomer added is 100 parts by weight of the alkyl (meth) acrylate.
0.1 to 3 parts by weight is preferable.

The above acrylic copolymer can be obtained by, for example, an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method or the like. In particular, the emulsion polymerization method is preferable from the viewpoint of easy control of the resin particle size. .

The above emulsion polymerization can be carried out by a conventionally known method. For example, an emulsion dispersant, a polymerization initiator, a pH adjuster, an antioxidant and the like may be added, if necessary.

Examples of the emulsifying dispersant include anionic surfactants, nonionic surfactants, partially saponified polyvinyl alcohol, cellulose dispersants, gelatin and the like. Commercially available anionic surfactants are listed. , For example,
Examples thereof include polyoxyethylene nonylphenyl ether sulfate (“Hitenol N-08” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

Examples of the above-mentioned polymerization initiator include water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate and hydrogen peroxide solution; organic peroxides such as benzoyl peroxide and lauroyl peroxide; azobisisobutyrate. Examples thereof include azo polymerization initiators such as ronitrile.

The emulsion polymerization method is not particularly limited, and examples thereof include (1) batch polymerization method, (2) monomer dropping method, and (3) emulsion dropping method.

(1) In the above batch polymerization method, pure water, an emulsifying dispersant, a polymerization initiator and a mixed monomer (the above acrylic monomer + polyfunctional monomer) are added all at once into a jacketed polymerization reactor. After sufficiently stirring and emulsifying under nitrogen stream pressure, the temperature in the reactor is raised by a jacket to start the reaction. (2) In the monomer dropping method, pure water, an emulsifying dispersant and a polymerization initiator are put in a jacketed polymerization reactor, the temperature in the reactor is raised under a nitrogen stream, and then the mixed monomer (the acrylic monomer is used). + Polyfunctional monomer) is added dropwise in a fixed amount to start the polymerization reaction. (3) In the emulsion dropping method, the mixed monomer (the above acrylic monomer + polyfunctional monomer), the emulsifying dispersant and pure water are stirred to prepare the emulsifying monomer in advance, and then
Pure water and a polymerization initiator are put in a jacketed polymerization reactor, the temperature inside the reactor is raised under a nitrogen stream, and then the emulsified monomer is added dropwise in a fixed amount to start the polymerization reaction.

The acrylic copolymer is not particularly limited in terms of morphology and structure. For example, if the acrylic copolymer has a so-called core / shell structure in which the monomer composition and cross-linking structure in the surface layer portion of the resin particle are different from that in the resin particle, Is preferable and the strength performance of the molded article is improved.

As a method of forming the core / shell structure, for example, a polymerization modifier is added to an emulsified monomer prepared from a mixed monomer, pure water and an emulsifier constituting the core part to carry out a polymerization reaction. Form resin particles. Next, an emulsion monomer prepared from the mixed monomer forming the shell portion, pure water and an emulsifier is added, and graft copolymerized on the core portion. In the resin particles thus obtained, the shell part three-dimensionally covers the surface of the core part, and the copolymer constituting the shell part and the copolymer constituting the core part are partially formed. To form a three-dimensional crosslinked structure. In the above method, the graft copolymerization of the shell part may be continuously performed in the same polymerization step as the polymerization of the core part.

The ratio of the core part to the shell part can be adjusted by adjusting the ratio of the mixed monomer forming the core part and the mixed monomer forming the shell part in the emulsion polymerization method.

In the present invention, a vinyl chloride resin can be obtained by graft-copolymerizing vinyl chloride onto the resin particles made of the above acrylic copolymer by a known method. Examples of the graft copolymerization method include a method of suspension-grafting vinyl chloride in the acrylic copolymer in an emulsified state.

The vinyl chloride resin used in the present invention is
It is obtained by graft-copolymerizing 30 to 60 wt% of the acrylic copolymer with 70 to 40 wt% of vinyl chloride,
The acrylic copolymer is preferably 30 to 40% by weight. When the content of the acrylic copolymer is less than 30% by weight, the obtained pipe or joint cannot give sufficient flexibility, and when it exceeds 60% by weight, sufficient tensile strength cannot be given and pressure resistance is low. Run short.

The pipe or joint of the present invention is obtained by molding a resin composition containing the vinyl chloride resin and a processing aid made of an acrylic resin. The processing aid functions to adjust the kneading state of the vinyl chloride resin at the time of molding and to improve the appearance and mechanical strength such as tensile strength of the obtained pipe or joint.

Examples of the processing aid made of the acrylic resin include (meth) acrylate homopolymers such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate; the above (meth) acrylate. A copolymer of two or more monomers selected from the following; a copolymer of the above (meth) acrylate and a vinyl monomer such as styrene, vinyltoluene and acrylonitrile.

The weight average molecular weight of the processing aid is not particularly limited, but is preferably 300,000 to 3.5 million. Examples of commercially available products of such processing aids include "Metabrene P-501A" and "Metabrene P" manufactured by Mitsubishi Rayon Co., Ltd.
-551A "and the like are preferably used.

The amount of the processing aid added is 0.5 to 7 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the vinyl chloride resin. Addition amount is 0.5
If the amount is less than the weight part, the surface of the molded product is deteriorated and the gloss is lost, and further sufficient kneading in the molding machine becomes difficult, resulting in insufficient strength (particularly tensile strength) of the molded product. On the other hand, if the amount is more than 7 parts by weight, the resin pressure in the molding machine becomes large, the molding machine needs to have a high pressure resistance design, and the production speed is further reduced, resulting in an increase in cost.

If necessary, compounding agents such as stabilizers, stabilizing aids, ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, lubricants, pigments and fillers are added to the above resin composition. May be done. The addition order and method of these compounding agents may be any method and are not particularly limited.

Examples of the stabilizer include organic tin compounds such as dibutyltin malate and dioctyltin laurate;
Lead white, basic lead sulfite, dibasic lead sulfite, tribasic lead sulfate, dibasic lead phosphite, silica gel coprecipitated lead silicate, lead stearate, lead benzoate, dibasic lead stearate,
Lead compounds such as lead naphthenate; metal soaps such as calcium stearate, barium stearate and zinc stearate; and inorganic stabilizers such as hydrotalcite and zeolite.

Examples of the stabilizing aid include epoxidized soybean oil, epoxidized linseed oil, phosphoric acid esters,
Phosphoric acid ester, olefin wax and the like,
Examples of the ultraviolet absorber include salicylic acid ester-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, and the like.

Examples of the light stabilizer include hindered amine compounds, and examples of the filler include:
Examples include calcium carbonate and talc. Examples of the plasticizer include aromatic esters such as dioctyl phthalate, examples of the antioxidant include phenolic antioxidants, and examples of the pigment include azo compounds, Examples thereof include phthalocyan-based, styrene-based, dye lake-based organic pigments; molybdenum chromate-based, ferrocyanide-based inorganic pigments and the like.

The pipe of the present invention can be obtained by extruding the above resin composition. Extrusion molding
It can be carried out by a conventionally known method, for example, using an extrusion molding line equipped with a cooling tank and a take-off machine under the temperature conditions of a barrel temperature of 150 to 190 ° C and a mold temperature of 180 to 200 ° C. The resin composition may be pelletized and used before extrusion molding.

Since the vinyl chloride resin is a graft copolymer, it is difficult to evaluate the degree of polymerization by a conventionally known method. However, considering the processability in extrusion molding, the preferable viscosity average degree of polymerization is 1. 1,000 to 2,000. Such a viscosity average degree of polymerization can be obtained by controlling the temperature during the graft polymerization to 40 to 55 ° C.

The joint of the present invention can be obtained by injection molding the above resin composition. Injection molding can be performed by a conventionally known method, for example, using a normal injection molding machine, for example, a barrel temperature of 150 ~ 190 ℃,
The nozzle temperature is 180 to 190 ° C, and the mold temperature is 30 ° C.

The vinyl chloride resin is not particularly limited, but, for example, considering the processability in injection molding,
A preferable viscosity average degree of polymerization is 500 to 1,200.
Such a viscosity average degree of polymerization can be obtained by controlling the temperature during graft polymerization to 55 to 70 ° C.

[0036]

Embodiments of the present invention will be described below. (Examples 1 to 8, Comparative Examples 1 to 4 and Comparative Examples 7 to 10) Preparation of Acrylic Copolymer Pure water and a polymerization initiator (ammonium persulfate) were placed in a reaction vessel equipped with a stirrer and a temperature controller, and the vessel was placed in the vessel. The inside of the reaction vessel was heated to 75 ° C. with stirring, after replacing the inside with nitrogen. Separately, pure water and emulsifier (“Hitenol N” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.
-08 "), and an emulsion monomer liquid was prepared from acrylic monomers (n-butyl acrylate and / or methyl methacrylate) and polyfunctional monomers (trimethylolpropane triacrylate) in the amounts shown in Tables 1 and 2. This emulsified monomer was dropped into the reaction vessel after heating at a constant dropping rate, and after dropping all emulsified monomers in 3 hours, stirring was continued for another 1 hour to complete the polymerization,
An acrylic copolymer latex (solid content concentration 30% by weight) was obtained. In addition, 1 part by weight of the emulsifying agent and 0.1 part by weight of the polymerization initiator were used with respect to 100 parts by weight of the acrylic monomer.

Preparation of vinyl chloride resin In a reaction vessel equipped with a stirrer and a temperature controller, pure water, the above acrylic copolymer latex, a dispersant (partially saponified polyvinyl alcohol, "Kuraray Poval L-" manufactured by Kuraray Co., Ltd.
8 ”) and a polymerization initiator (t-butylperoxydecanoate and α-cumylperoxyneodecanate) were added, and the air in the reaction vessel was discharged by a vacuum pump, and then vinyl chloride was added with stirring. . Then, the inside of the reaction vessel was heated to the temperatures shown in Tables 1 and 2 to start polymerization.
The reaction was stopped when the pressure in the reaction vessel dropped to 7 kgf / cm ² , and unreacted vinyl chloride was discharged to obtain a slurry copolymer. The obtained slurry-like copolymer was centrifugally dehydrated and then dried to obtain a vinyl chloride resin. The usage ratios of the constituents of the acrylic copolymer and vinyl chloride are shown in Tables 1 and 2. Further, with respect to 100 parts by weight of vinyl chloride, 200 parts by weight of pure water, 0.25 parts by weight of a dispersant, and 0.1 part of t-butylperoxydecanoate.
It was used in a proportion of 02 parts by weight and 0.04 parts by weight of α-cumylperoxyneodecanate.

Preparation of Resin Composition 100 parts by weight of the vinyl chloride resin obtained in Examples 1 to 4 and Comparative Examples 1 to 4 and organotin stabilizer (“ONZ-142F” manufactured by Sansha Machine Co., Ltd.) 1 part by weight of polyethylene lubricant (“Hiwax 220MP” manufactured by Mitsui Petrochemical Co., Ltd.)
5 parts by weight, 0.5 parts by weight of an ester-based lubricant (“Rikester EW100” manufactured by Riken Vitamin Co., Ltd.) and the processing aids in the amounts shown in Tables 1 and 2 were mixed using a Henschel mixer (manufactured by Kawada Kogyo Co., Ltd.). Then, a resin composition was prepared.

[0039]

[Table 1]

[0040]

[Table 2]

(Comparative Example 5) 100 parts by weight of a vinyl chloride homopolymer ("TK-1300" manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts by weight of dioctyl phthalate as a plasticizer, and the same and the same amount of processing aid as in Comparative Example 2 were used. Were mixed using a Henschel mixer (manufactured by Kawada Kogyo Co., Ltd.) to prepare a resin composition.

(Comparative Example 6) 100 parts by weight of a vinyl chloride homopolymer ("TK-1300" manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts by weight of an acrylic modifier ("Kane Ace FM" manufactured by Kanegafuchi Chemical Co., Ltd.) and comparison The same and the same amount of processing aid as in Example 2 was mixed using a Henschel mixer (Kawata Industry Co., Ltd.) to prepare a resin composition.

The following evaluations were carried out on the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 6, and the results are shown in Table 3. (1) Flexibility The resin composition was kneaded with an 8-inch roll to obtain a resin sheet, and then the resin sheet was press-molded at 200 ° C. to prepare a press sheet having a thickness of 3 mm. Using this press sheet, the flexural modulus at 23 ° C. was measured in accordance with the test method of JIS K7203 and used as an index for evaluating flexibility. Flexural modulus measured is 13,000k
When it was less than gf / cm ² , it was judged to have sufficient flexibility.

(2) Tensile strength The above resin composition was supplied to an extruder to obtain a barrel temperature of 10
Extrusion was performed under the conditions of 0 to 130 ° C. and the mold part temperature of 140 ° C., and pellets were obtained by a hot cut method. These pellets are fed into a 50 mm twin-screw different-direction extruder (“S
LM50 "), the barrel temperature is 150-190
Extruded under conditions of ℃, mold part temperature 170 ~ 200 ℃,
A pipe having an inner diameter of 20 mm, an outer diameter of 26 mm and a wall thickness of 3 mm was obtained. Using the sample cut out from the above pipe, JIS
The tensile strength at 23 ° C. was measured according to the test method of K6741.

(3) Impact strength Using the sample cut from the pipe obtained in (2),
The falling weight impact strength at −20 ° C. was measured according to the test method of JIS K6742.

(4) Surface property The glossiness of the pipe surface obtained in (2) was visually observed and the surface property was evaluated according to the following evaluation criteria. ◯: The surface has sufficient gloss. Δ: The surface is not glossy. X: The surface is rough or has obvious irregularities.

[0047]

[Table 3]

(Examples 5-8, Comparative Examples 7-10) Preparation of Resin Composition 100 parts by weight of the vinyl chloride resin obtained in the above Examples 5-8 and Comparative Examples 7-10, organotin stabilizer (Sanko Machine Tin Co., "ONZ-142F") 1 part by weight, polyethylene lubricant (Mitsui Petrochemical Co., Ltd. "Hiwax 220MP") 0.
5 parts by weight, 0.5 parts by weight of an ester-based lubricant (“Rikester EW100” manufactured by Riken Vitamin Co., Ltd.) and the processing aids in the amounts shown in Tables 1 and 2 were mixed using a Henschel mixer (manufactured by Kawada Kogyo Co., Ltd.). Then, a resin composition was prepared.

(Comparative Example 11) 100 parts by weight of a vinyl chloride homopolymer ("TK-800" manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts by weight of dioctyl phthalate as a plasticizer, and the same and the same amount of processing aid as in Comparative Example 8 were used. Were mixed using a Henschel mixer (manufactured by Kawada Kogyo Co., Ltd.) to prepare a resin composition.

(Comparative Example 12) 100 parts by weight of a vinyl chloride homopolymer ("TK-800" manufactured by Shin-Etsu Chemical Co., Ltd.) and 40 parts by weight of an acrylic modifier ("Kaneace FM" manufactured by Kanegafuchi Chemical Co., Ltd.) were used. The same and the same amount of processing aid as in Example 8 was mixed using a Henschel mixer (Kawata Industry Co., Ltd.) to prepare a resin composition.

The following evaluations were performed on the resin compositions of Examples 5 to 8 and Comparative Examples 7 to 12, and the results are shown in Table 4. (1) Flexibility The resin composition was kneaded with an 8-inch roll to obtain a resin sheet, and then the resin sheet was press-molded at 200 ° C. to prepare a press sheet having a thickness of 3 mm. Using this press sheet, the flexural modulus at 23 ° C. was measured in accordance with the test method of JIS K7203 and used as an index for evaluating flexibility. Flexural modulus measured is 13,000k
When it was less than gf / cm ² , it was judged to have sufficient flexibility.

(2) Tensile strength The above resin composition was fed to an extruder to obtain a barrel temperature of 10
Extrusion was performed under the conditions of 0 to 130 ° C. and the mold part temperature of 140 ° C., and pellets were obtained by a hot cut method. Using a injection molding machine with a mold clamping pressure of 100 tons (“J100E-C5” manufactured by Japan Steel Works, Ltd.), the pellets were heated to a barrel temperature of 1
50-180 ℃, mold part temperature 30 ℃, injection speed 70%,
Extrusion molding was performed under the conditions of an injection pressure of 70% to obtain a pipe joint having a receiving diameter of 20 mm. Using the sample cut out from this joint, in accordance with the test method of JIS K6741, 23 ℃
Was measured for tensile strength.

(3) Impact strength Using the sample cut from the joint obtained in (2), J
The falling weight impact strength at −20 ° C. was measured according to the test method of IS K6742.

(4) Surface property: The joint surface obtained in (2) is visually observed for its glossy state.
The surface property was evaluated according to the following evaluation criteria. ◯: The surface has sufficient gloss. Δ: The surface is not glossy. X: The surface is rough or has obvious irregularities.

[0055]

[Table 4]

[0056]

EFFECTS OF THE INVENTION The pipe or joint excellent in flexibility and impact resistance of the present invention has the above-mentioned constitution, has appropriate flexibility and exhibits sufficient impact strength even at low temperature, Since it shows excellent performance against deformation and impact, it can be suitably used for applications such as pipelines that require vibration resistance and cold resistance that could not be used with conventional vinyl chloride pipe materials .

Claims (1)

[Claims] 1. A partially crosslinked acrylic copolymer 30 to 60 containing 50% by weight or more of an alkyl (meth) acrylate whose homopolymer has a second-order transition degree of less than −20 ° C.
A resin composition comprising 100 parts by weight of a vinyl chloride resin obtained by graft-polymerizing 70% to 40% by weight of vinyl chloride to 0.5% by weight and 0.5 to 7 parts by weight of an acrylic processing aid. A pipe or joint with excellent flexibility and impact resistance.