JPH06286012A - Vinyl chloride resin pipe - Google Patents

Abstract

PURPOSE:To obtain a vinyl chloride resin pipe not eluting lead by mixing a composite petal soap type and/or organotin type stabilizer containing no lead with a vinyl chloride type polymer containing partially saponified polyvinyl alcohol PVAA, partially saponified polyvinyl alcohol PVAB, a secondary dispersant and water-soluble cellulose ester as dispersants for suspension polymerization and molding the resulting mixture. CONSTITUTION:A vinyl chloride resin pipe is obtained by a vinyl chloride polymer (PVC) obtained by the suspension polymerization of a mixture (vinyl chloride type monomer mixture) of vinyl chloride and a monomer copolymerizable with vinyl chloride in an aqueous medium. PVC is produced using PVAA with a saponification degree of 70-90mol% and an average polymerization degree of 1500-3000, PVAB with a saponification degree of 70-90mol% and an average polymerization degree of 300-1000, a secondary dispersant whose amt. is 0-2.0 pts.wt. with respect to 100 pts.wt. of the vinyl chloride monomer and water-soluble cellulose ester whose amt. of 0-0.5 pts.wt. with respect to 100 pts.wt. of the vinyl chloride monomer as dispersion stabilizers for suspension polymerization. A composite metal soap type and/or metal tin type stabilizer containing no lead is mixed with the dispersion stabilizers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin pipe, and is particularly vinyl chloride-free and has excellent mechanical strength, heat distortion temperature and appearance without lead elution into the fluid in the pipe. Related to resin pipes.

[0002]

2. Description of the Related Art Vinyl chloride polymers (hereinafter referred to as PVC) are used in various fields because they have excellent physical and mechanical properties.

PVC is used in combination with various stabilizers for the purpose of suppressing decomposition at the time of molding, and a typical stabilizer system is a composite metal soap stabilizer and / or an organotin stabilizer. Is preferably used in applications requiring substantially non-toxicity such as water pipes and fittings, food packaging materials, medical instruments, pharmaceutical packaging materials, etc. As the trend is increasing, replacement of lead-based stabilizers is progressing.

Generally, lead-based stabilizers are inexpensive and P
While it has a high ability to stabilize VC, composite metal soap-based stabilizers and organotin-based stabilizers are inferior to lead-based stabilizers in terms of PVC stabilizing effect and are expensive. , Even if it is used in a large amount, the effect commensurate with the cost cannot be expected. Therefore, for such complex metal soap-based stabilizers and organotin-based stabilizers, a compound (hereinafter, referred to as a stabilizing aid) for promoting the effect of the stabilizer is used. And / or its ester,
Phosphite compounds, epoxy compounds, sulfur-containing compounds, sterically hindered phenols, etc. have been known so far, and P
It may be added and used in the production of VC, or used in the compounding and kneading steps prior to processing.

Among them, when a liquid phosphite or a liquid epoxy compound is used, even if sufficient thermal stability is expected, the heat distortion temperature represented by the Vicat softening temperature is lowered. It is not preferable because it may invite.

When powdered dipentaerythritol, phosphite, epoxy compounds, sulfur-containing compounds, sterically hindered phenols, etc. are used, these compounds are PV.
As a result of poor compatibility with C, poor dispersion may occur and mechanical strength such as impact resistance may decrease.

Incidentally, partially saponified polyvinyl alcohol (hereinafter referred to as PVA) is a general dispersant for suspension polymerization of PVC, but it is classified into the above-mentioned polyols and highly effective as a stabilizing aid. Molecular Papers, Vol. Four
7, No. 6, pp. 509 (June, 1990) and the like. However, when PVA is used for the purpose of improving the thermal stability of PVC, and when used in the mixing and kneading steps, PVA having a high saponification degree is used.
(In particular, PVA having a saponification degree of 70 mol% or more)
As a result of poor compatibility with C, there is a possibility that impact resistance and other mechanical strength may be reduced due to poor dispersion. When PVA having a low degree of saponification is used, it has to be used in a large amount due to its poor ability as a stabilizing aid, and as a result, the same problem as PVA having a high degree of saponification may occur.

On the other hand, when it is used as a dispersion stabilizer during the suspension polymerization of PVC to improve the thermal stability of PVC, P
Although the dispersibility of VA is improved and the vinyl chloride monomer is graft-polymerized to PVA, the compatibility with PVC is improved and the strength deterioration due to the poor dispersion of PVA is not recognized, but a better heat resistance is obtained. A large amount of P for stability
When VA is used, the dispersion stability of the vinyl chloride-based monomer during the suspension polymerization of PVC is lowered and PVC cannot be obtained, or the obtained PVC has plasticizer absorbency and fish eyes, This results in a polymer having a reduced level of vinyl chloride remaining in PVC, which causes another problem that a pipe molded article having satisfactory appearance, mechanical strength and hygiene cannot be obtained.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vinyl chloride resin pipe having no lead elution into a pipe fluid and having satisfactory physical properties.

[0010]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to solve the above problems, a certain PV
A composition obtained by mixing PVC produced using a combination of A and cellulose as a dispersion stabilizer and a small amount of a lead-free small amount of a composite metal soap stabilizer and / or an organotin stabilizer is a pipe A pipe molded from this composition has the thermal stability necessary for molding, is substantially non-toxic without lead elution, has no appearance defects due to fish eyes, etc., and has mechanical strength such as impact resistance. The present invention has been completed by discovering that the heat distortion temperature is practically sufficient.

That is, the present invention provides a vinyl chloride resin pipe obtained by molding a PVC obtained by suspension polymerization of a vinyl chloride monomer in an aqueous medium, wherein the PVC is
(A) Saponification degree is 70 to 90 mol% and average degree of polymerization is 1
PVA of 500 to 3000, (B) saponification degree of 70 to 9
PVA having 0 mol% and an average degree of polymerization of 300 to 1000,
The secondary dispersant (C) is 0 to 2.0 parts by weight with respect to 100 parts by weight of the vinyl chloride-based monomer, and the water-soluble cellulose ether (D) is 0 to 100 parts by weight with respect to the vinyl chloride-based monomer.
0.5 parts by weight Using PVC produced in combination as a dispersion stabilizer in suspension polymerization, and mixing it with a lead-free composite metal soap-based stabilizer and / or organotin-based stabilizer Is a pipe made of vinyl chloride resin. Hereinafter, the present invention will be described in detail.

In the present invention, a composite metal soap stabilizer and / or
Alternatively, PVA (A) and PV used in the production of PVC mixed with an organotin stabilizer and used for pipe molding
The total amount of A (B) used is preferably 0.06 parts by weight or more and 1.5 parts by weight or less, and more preferably 0.06 parts by weight or more, with respect to 100 parts by weight of the vinyl chloride-based monomer. It is in the range of 0.3 parts by weight or less. This usage is 0.06
If the amount is less than 1 part by weight, it may not be possible to obtain sufficient heat stability when molding a pipe by mixing with a complex metal soap stabilizer and / or an organic tin stabilizer, resulting in poor hue and appearance. Only 1.5 pipes may be obtained, 1.5
If the amount is more than the amount by weight, the appearance of the resulting pipe is poor, the mechanical strength such as impact resistance is lowered due to the presence of ungelled particles, and the residual monomer in PVC increases, resulting in the residual monomer in the pipe. Sometimes, only pipes with poor hygiene can be obtained.

Further, as the secondary dispersant (C), oil-soluble PVA or a surfactant can be used. When the secondary dispersant (C) is used in the present invention, the amount of ungelled particles in the pipe is reduced, and a pipe having more excellent mechanical strength such as appearance and impact resistance can be obtained. When oil-soluble PVA is used as the secondary dispersant (C), the amount used is 0.1 parts by weight or less based on 100 parts by weight of the vinyl chloride-based monomer,
It is preferably 0.005 to 0.05 parts by weight. If the amount used exceeds 0.1 part by weight, PVC obtained
In some cases, the bulk specific gravity decreases, the productivity of the pipe decreases, and the PVC contains a large amount of fine particles. As a result, the powder flowability of the composition used for molding the pipe decreases, and eventually This may cause variations in the molding speed of the pipe and the amount of protrusion, making it difficult to obtain a pipe of uniform quality.

When a surfactant is used as the secondary dispersant (C), the amount of the surfactant used is vinyl chloride monomer 1
The amount is preferably 2.0 parts by weight or less, more preferably 0.1 to 1.0 parts by weight with respect to 00 parts by weight. If the amount used exceeds 2.0 parts by weight, fine particles may increase in the PVC, and the above-mentioned oil-soluble PV
Similar problems can occur as when A is used in excess.

The water-soluble cellulose ether (D) may be any known water-soluble cellulose ether such as methyl cellulose and hydroxypropyl cellulose, but preferably hydroxypropylmethyl cellulose is used, and more preferably 1 The degree of hydroxypropoxyl group substitution per glucose unit is 0.15 to 0.
It is desirable that it is 25 and hydroxypropyl methylcellulose having a methoxyl group substitution degree of 1.4 to 1.9. Further, the amount used is preferably 0.5 parts by weight or less based on 100 parts by weight of the vinyl chloride-based monomer,
If it exceeds 0.5 parts by weight, the fine particles in the PVC will increase, and the molding speed and the amount of protrusion will also vary, and it will be difficult to obtain a pipe of uniform quality.
The more preferable amount of the water-soluble cellulose ether (D) used is 0.1% with respect to 100 parts by weight of the vinyl chloride-based monomer.
It is 005 to 0.1 parts by weight, and if it is less than 0.005 parts by weight, the dispersion stability of the vinyl chloride-based monomer is reduced, coarse particles of PVC are obtained, and a pipe molded from such PVC is There is a possibility that mechanical strength such as impact resistance may be inferior. On the other hand, when it exceeds 0.1 parts by weight, PVC having a low bulk specific gravity may be obtained and the productivity of the pipe may be reduced.

When the secondary dispersant (C) and / or the water-soluble cellulose ether (D) is not used, P
It is preferable to use VA (A) and (B) in a weight ratio of 1: 2 to 1:15, and when (B) is less than twice the amount of (A), the presence of ungelled particles is present. As a result, mechanical strength such as striking resistance may decrease, or residual monomers in PVC may increase, resulting in increased residual monomers in the pipe, resulting in only a pipe with poor hygiene.
When the amount is more than the double amount, the dispersion stabilizer of the vinyl chloride-based monomer is inferior and particles are not obtained, or the obtained particles are coarse. In a pipe manufactured using coarse particles, the amount of ungelled particles may increase and mechanical strength such as impact resistance may decrease.

The above-mentioned dispersion stabilizer may be used by adding the entire amount thereof to the polymerization system before the initiation of the polymerization, and a part of the dispersion stabilizer may be divided or continuous after the initiation of the polymerization and before the termination of the polymerization. It may be added and used, or may be added and used after the termination of the polymerization and before the dehydration of the slurry, but it is preferably added and used all at once before the start of the polymerization.

The vinyl chloride-based monomer used in the production of the vinyl chloride-based polymer used in the present invention includes vinyl chloride alone and a monomer mixture containing vinyl chloride as a main component (vinyl chloride 50% by weight). % Or more), and examples of the monomer copolymerizable with vinyl chloride to be used in this mixture include vinyl acetate, vinyl propionate and other vinyl esters, methyl acrylate, ethyl acrylate and other acrylic esters or methacrylic acid. Examples thereof include acid esters, olefins such as ethylene and propylene, maleic anhydride, acrylonitrile, styrene and vinylidene chloride.

The surfactant used for the production of PVC used in the present invention may be any of nonionic, cationic and anionic surfactants, such as polyoxyethylene alkyl ester and polyoxyethylene. Alkyl ether, polyoxyethylene allyl ether, polyoxyethylene sorbitan fatty acid ester,
Nonionic surfactants such as polyoxyethylene sorbitol fatty acid ester, block copolymer of polyoxyethylene and polyoxypropylene, glycerin fatty acid ester, polysiloxane polyoxyalkylene block copolymer, polyoxyethylene alkylamine and the like;
Cationic surfactants such as aromatic ammonium salts, alkyl amine salts, quaternary ammonium salts, and alkyl imidazoline quaternary salts; alkyl sulfonates, alkyl allyl sulfonates, alkyl phosphates, polyoxyethylene alkyl phosphates , An anionic surfactant such as polyoxyethylene alkylallyl sulfonate, and these can be used alone or in combination of two or more kinds. The hydrophilic / hydrophobic balance of the surfactant is preferably 15 or less. When it exceeds 15, the PVC is not obtained, the appearance of the pipe is deteriorated, and the ungelled particles in the pipe increase. In some cases, mechanical strength such as impact resistance may be reduced, or only pipes with poor hygiene may be obtained due to residual monomers.

There is no particular limitation on the method for producing the PVC used for molding the pipe in the present invention, and it is carried out under the conditions of known suspension polymerization.

For example, the amount of the aqueous medium used per monomer, the amount of the polymerization initiator, the polymerization temperature, etc. may be in the conventionally employed range. If necessary, known protective colloids, pH adjusters, chain transfer agents and the like may be used as long as they do not affect the effects of the present invention.
Further, when a combined metal soap-based stabilizer and an organotin-based stabilizer are used together as a stabilizer or when an organotin-based stabilizer is used alone, a mercapto group, a hydroxyl group and / or
Alternatively, it is desirable to use PVC produced by using a chain transfer agent having a carboxyl group. Examples of such a chain transfer agent include 2-mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, thioglycerin, and thiol. Propylene glycol, thioacetic acid and the like are exemplified, but 2-mercaptoethanol is preferably used.

Further, as the kind of the composite metal soap-based stabilizer used by mixing with PVC, a combination of an organic acid salt of zinc and an organic acid salt of an alkali metal and / or an alkaline earth metal is used. be able to. Among these, examples of the type of alkali metal and / or alkaline earth metal include lithium, sodium, potassium, magnesium, calcium and the like, and among them, a combination of calcium and zinc is preferable. Examples of the organic acid include formic acid, acetic acid,
Examples thereof include, but are not limited to, carboxylic acids such as propionic acid, caprylic acid, lauric acid, palmitic acid and stearic acid. The amount of the composite metal soap-based stabilizer used is preferably 0.5 to 5 parts by weight, and more preferably 1 to 3 parts by weight, per 100 parts by weight of the vinyl chloride polymer. If it is less than 0.5 part by weight, the thermal stability may be insufficient, and the resulting pipe may be colored or the mechanical strength may be reduced.
If it exceeds 5 parts by weight, thermal stability commensurate with the amount added is not expected and it is not practical. Further, in addition to these composite metal soap-based stabilizers, an organotin-based stabilizer described later may be mixed.

The type of the organotin-based stabilizer used by mixing with PVC is not particularly limited as the usual organotin-based stabilizer for PVC is used, but there is a concern that the stabilizer may elute into the pipe fluid. In this case, it is preferable to use a non-toxic or low-toxic organotin stabilizer, and such a non-toxic or low-toxic organotin stabilizer is di-n-octyltin-S, S'-bis (isooctylmercapto). Acetate) represented by octyltin mercaptide system; di-n
-Octyl tin-S, S'-bis (isooctyl maleate), octyl tin maleate represented by n-octyl tin maleate polymer, or an organic tin stabilizer mainly composed of these. It is not limited. The amount of the organotin stabilizer used is preferably 0.5 to 5 parts by weight, and more preferably 1 to 3 parts by weight, based on 100 parts by weight of the vinyl chloride polymer. If it is less than 0.5 part by weight, the thermal stability may be insufficient, and the resulting vipe may be colored or the mechanical strength may be reduced. If it exceeds 5 parts by weight, thermal stability commensurate with the amount added is not expected and it is not practical. Further, in addition to these organotin stabilizers, the above-mentioned composite metal soap stabilizer may be mixed.

The above PVC composition includes phosphites, epoxy compounds, polyols or derivatives thereof such as dipentaerythritol, antioxidants, stabilizing aids such as zeolite and perchlorate, and processing aids. Ordinary additives such as plasticizers, lubricants, pigments, fillers, etc., as well as resins other than vinyl chloride, other modifiers may be mixed and used within a range that does not affect the effect of the present invention. It is necessary to contain no organic or inorganic lead compounds typified by tribasic lead sulfate and lead stearate.

As a method for mixing the PVC, the composite metal soap stabilizer and / or the organotin stabilizer, and other additives, a conventionally used method is adopted, such as a Henschel mixer or a super mixer. It can be performed at room temperature or by heating and mixing with a mixer or a ribbon blender. further,
The mixed powder composition may be preliminarily kneaded and then pelletized, or the powder may be directly molded. It is also possible to use a method in which some of the additives are directly supplied to a molding machine at the time of molding the pipe.

The method of forming the mixture into a pipe may also be a conventionally used method, and generally extrusion molding is used, in which case the type of extruder, the shape of the screw, the cylinder and the die are used. The temperature and other molding conditions may be those conventionally used and are not particularly limited.

The pipe of the present invention can be used for water pipes, electric pipes,
Examples include industrial piping.

[0028]

EXAMPLES The vinyl chloride resin pipe of the present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited thereto.

The following physical properties were measured by the following methods.

(Preparation of composition) 200 L manufactured by Henschel
A composition was obtained using a mixer under the following formulation and conditions.

<Formulation 1> Vinyl chloride resin 100 parts by weight Polyethylene wax 0.3 parts by weight Glycerin monostearate 0.2 parts by weight Ca-Zn complex metal soap-based stabilizer 3.0 parts by weight <Formulation 2> Chloride Vinyl resin 100 parts by weight Acrylic processing aid 1.0 parts by weight Ester wax 1.0 parts by weight Organotin stabilizer 2.0 parts by weight (dioctyl tin malate polymer) <Mixing conditions> Cutting temperature: 150 ° C Cooling Temperature: 50 ° C.

(Molding of Pipe) A pipe having a nominal diameter of 50 mm was molded from the above composition using a twin-screw extruder (model KMD-50K) manufactured by Mitsubishi Polymer.

<Molding conditions> Set temperature / heater 1: 170 ° C. heater 2: 185 ° C. heater 3: 190 ° C. screw: 80 ° C. adapter: 155 ° C. die 1: 165 ° C. die 2: 175 ° C. die 3: 180 ° C. die 4 : 190 ° C. Die 5: 195 ° C. Screw rotation speed: 36 rpm Feed rotation speed: 55 rpm Vent vacuum degree: 580 mm / Hg.

(Impact resistance) Using a test piece cut out from a pipe molded by the method described in the above paragraph, JISK 7
According to 111, the impact resistance was evaluated by the Charpy impact test. The hammer load was 40 kgf.

(Thermal Deformability) Using a test piece cut out from a pipe in the same manner as the above, according to JIS K 7206,
The thermal deformability was evaluated by the Vicat softening temperature test.

Example 1 In a stainless steel polymerization container having an internal volume of 1 cubic meter, 450 kg of deionized water, 400 kg of vinyl chloride monomer, Table 1
The kind and amount of the dispersant shown in the above are charged as an aqueous solution or a mixed solution of methyl alcohol and water, and 0.045 parts by weight of butyl neodecanoate is used as an initiator, and the temperature is adjusted to
The reaction was carried out at 7.4 ° C to a conversion rate of 85%. The water-soluble cellulose ether had a hydroxypropoxyl group substitution degree of 0.25 and a methoxyl group substitution degree of 1.9, and the viscosity of a 2% by weight aqueous solution at 20 ° C. was 50 cps. Hydroxypropyl methylcellulose (HPMC) was used.

After the polymerization, the unreacted vinyl chloride monomer is recovered, the system is evacuated and replaced with nitrogen, and the vinyl chloride polymer slurry is taken out and dehydrated and dried to obtain a polymer. After adjusting the composition of the compounding 1 and the compounding 2, the pipe was shape | molded and the impact resistance and heat distortion test were implemented. The results are shown in Tables 3 and 4.

Example 2 Example 2 was repeated except that the amount of PVA (B) used was 0.06 parts by weight.

Example 3 PVA (B) was added 2 hours after the initiation of polymerization, except that
The same procedure as in Example 1 was performed.

Comparative Example 1 The procedure of Example 1 was repeated except that PVA (B) was not used.

Comparative Example 2 Comparative Example 1 except that the amount of PVA (C) shown in Table 1 was used.
I went the same way.

Comparative Example 3 The procedure of Comparative Example 1 was repeated except that the amounts of PVA (A), (B) and HPMC shown in Table 1 were used.

Example 4 In a stainless steel polymerization container having an internal volume of 1 cubic meter, 450 kg of deionized water, 400 kg of vinyl chloride monomer, Table 2
The dispersant of the type and amount shown in (1) is charged as an aqueous solution or a mixed solution of methyl alcohol and water, 0.045 parts by weight of butyl neodecanoate is used as an initiator, and 0.016 parts by weight of 2-mercaptoethanol is used as a chain transfer agent. Was reacted at a temperature of 53.0 ° C. to a conversion of 85%, unreacted vinyl chloride monomer was recovered, the system was evacuated and replaced with nitrogen, and a vinyl chloride polymer slurry was taken out. After dehydration and drying to obtain a polymer, and the compositions of formulation 1 and formulation 2 were prepared according to the above-mentioned method, a pipe was molded and impact resistance and heat deformation test were conducted. The results are shown in Tables 5 and 6.

Example 5 Example 4 was repeated except that 0.01 part by weight of PVA (C) was used as the secondary dispersant.

Example 6 The same procedure as in Example 5 was carried out except that 0.2 parts by weight of polyoxyethylene sorbitan monostearate as a surfactant was used as a secondary dispersant instead of PVA (C). .

Comparative Example 4 PVC polymerized using the amounts of PVA (A) shown in Table 2.
The same procedure as in Example 4 was carried out except that

Comparative Example 5 Example 4 was repeated except that the amounts of PVA (A) and PVA (C) shown in Table 2 were used.

Comparative Example 6 Example 4 was repeated except that the amounts of PVA (A) and cellulose ether shown in Table 2 were used.

Comparative Example 7 Example 4 was repeated except that the amounts of PVA (B), PVA (C) and cellulose ether shown in Table 2 were used.

Comparative Example 8 The PVC used in Comparative Example 1 was blended with 2 parts by weight of epoxidized soybean oil in addition to the additive of the above-mentioned formulation, and the thermal stability test, pipe molding, and impact resistance test were conducted. The heat deformability test was performed.

Comparative Example 9 The procedure of Comparative Example 5 was repeated except that 2 parts by weight of PVA2 was used instead of the epoxidized soybean oil.

The dispersant formulations for the examples and comparative examples are shown in Tables 1 and 2. Table 3 shows the measurement results of Examples and Comparative Examples.
~ 6.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

[0059]

As described above, since the vinyl chloride resin pipe of the present invention does not use a lead compound as a stabilizer, it has no lead elution into the pipe fluid. It has excellent physical properties in terms of impact resistance and heat distortion temperature, and its appearance is also good.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 29:04)

Claims (1)

[Claims] 1. A mixture of vinyl chloride or a monomer copolymerizable with vinyl chloride (hereinafter referred to as vinyl chloride monomer).
In a vinyl chloride resin tube formed by molding a vinyl chloride polymer obtained by suspension polymerization in an aqueous medium, (A) having a saponification degree of 70 to 70 as the vinyl chloride polymer.
90 mol% and partially saponified polyvinyl alcohol (hereinafter referred to as PVA) having an average degree of polymerization of 1500 to 3000,
(B) Saponification degree is 70 to 90 mol% and average degree of polymerization is 3
0 to 1000 parts by weight of PVA, (C) secondary dispersant based on 100 parts by weight of vinyl chloride monomer, and (D) 100 parts by weight of water-soluble cellulose ether. 0 to 0.5 part by weight per part by weight of a vinyl chloride polymer produced in combination as a dispersant in suspension polymerization, and a lead-free composite metal soap stabilizer and / or organotin A vinyl chloride resin pipe formed by molding a composition containing a system stabilizer.