JP3234632B2 - Method for producing vinyl chloride resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride resin suitable for medical use.

[0002]

2. Description of the Related Art A vinyl chloride resin produced by aqueous suspension polymerization is generally used as a vinyl chloride resin for medical use, and divinyl chloride generally known as a non-toxic compound is used for this vinyl chloride resin. After adding and compounding 2-ethylhexyl phthalate, calcium and zinc metal soap-based stabilizers, epoxidized soybean oil, lubricants, etc., the Japanese Pharmacopoeia 10th Edition General Test Method 42, "Plastic Container Test Method for Infusion (Pharma Criteria) ”and the like.

JP-B-58-17625 discloses a resin composition for medical equipment containing a copolymer of vinyl chloride and alkyl acrylates and at least one metal oxide such as magnesium oxide. It is shown.

Japanese Patent Publication No. Sho 61-46492 discloses a medical vinyl chloride resin composition containing at least one kind of metal oxide such as magnesium oxide and used for radiation sterilization. Considering the effect on the human body, the amount of the additive eluted needs to be very low.

[0005]

However, non-toxic products using a common vinyl chloride resin have a problem that the amount of zinc eluted is large and the pH difference (ΔpH) between the test solution and the blank test solution is large. Some improvements are desired. This is because zinc metal soap is used in a non-toxic formulation that is generally said to be the least harmful stabilizer system to the human body, and a part of it is eluted in an elution test.

[0006] In addition, since non-toxic compounds are inferior in thermal stability to other compounds, they tend to be thermally deteriorated during molding, and their dehydrochlorination is Δ
It is thought to increase the pH difference.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above problems, and have completed the present invention.

That is, the present invention relates to a method for producing a vinyl chloride resin by aqueous suspension polymerization of vinyl chloride, wherein magnesium oxide and / or hydrotalcite are added during the polymerization, and polyvinyl alcohol and cellulose are used as suspension stabilizers. A method for producing a vinyl chloride resin, which comprises using a derivative in combination.

[0009] The vinyl chloride monomer in the present invention also includes a mixture of a monomer copolymerizable with vinyl chloride.
As the copolymerizable monomer, for example, ethylene, propylene, 1-butene, 1-pentene, 1-octene,
2-carbon such as 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, etc.
30, α-olefins, methacrylic acid and its esters, maleic acid and its esters, vinyl compounds such as vinyl acetate, vinyl propionate and alkyl vinyl ether, and mixtures thereof. Of these, homopolymerization of a vinyl chloride monomer is preferred.

It is not clear why the addition of magnesium oxide and / or hydrotalcite at the time of polymerization reduces the amount of zinc eluted and reduces ΔpH, but it is not clear why the surface of the primary particles before the formation of vinyl chloride particles is formed. Neutralizes the adhered HCl, which reduces the amount of zinc eluted,
It is likely that ΔpH will decrease.

When the magnesium oxide and / or hydrotalcite are added, the conversion of the vinyl chloride monomer is 5%.
It is preferably up to 0% by weight, more preferably up to 20% by weight, and may be added before polymerization.
If the conversion exceeds 50% by weight, the effect of lowering the zinc elution amount is small, and the ΔpH is undesirably large.

The amount of magnesium oxide and / or hydrotalcite added is preferably 10 to 1000 ppm by weight, based on the total amount of the vinyl chloride monomer used in the polymerization.
500 wt ppm is more preferred, and 40 to 300 wt ppm is particularly preferred. If the addition amount exceeds 1000 wt ppm, the resulting vinyl chloride resin particles are likely to be coarse, and are undesirably colored after molding. On the other hand, if the addition amount is less than 10 wt ppm, the effect of suppressing the dissolution of zinc and the fluctuation of pH is undesirably small.

[0013] The magnesium oxide and hydrotalcite used in the present invention may be generally commercially available, but more preferably those used for food addition.

The suspension stabilizer used in the present invention is a combination of polyvinyl alcohol and a cellulose derivative.

Examples of the polyvinyl alcohol include completely saponified or partially saponified polyvinyl alcohol. The saponification degree of polyvinyl alcohol is preferably from 60 to 99 mol%, more preferably from 65 to 95 mol%,
0-85 mol% is particularly preferred. When the saponification degree is lower than 60 mol% or higher than 99 mol%, it is considered that the protective colloid property is small, but the particles of the obtained vinyl chloride resin tend to be coarse, which is not preferable.

The degree of polymerization of the polyvinyl alcohol used in the present invention is preferably from 200 to 3,500, more preferably from 500 to 300.
0 is more preferable, and 600 to 2500 is particularly preferable.
When polyvinyl alcohol having a polymerization degree lower than 200 is used, the protective colloid property is low, and the particles of the obtained vinyl chloride resin tend to be coarse, which is not preferable. Polymerization degree is 3
When polyvinyl alcohol higher than 500 is used, the polyvinyl alcohol hardly dissolves in water, and the viscosity of the aqueous solution increases, which is not suitable for practical use. Polyvinyl alcohol can be used alone or in combination of two or more.

Examples of the cellulose derivative include methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose and the like, with hydroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose being preferred. These cellulose derivatives can be used alone or in combination of two or more.

The proportion of polyvinyl alcohol in the suspension stabilizer is preferably 95 to 10% by weight, more preferably 90 to 20% by weight, and particularly preferably 75 to 35% by weight. If the proportion of polyvinyl alcohol in the suspension stabilizer is higher than 95% by weight or lower than 10% by weight, the resulting polyvinyl chloride resin particles tend to be coarse, which is not preferred.

The amount of the suspension stabilizer used in the present invention is 300 to 300 parts based on the total amount of the vinyl chloride monomer used for the polymerization.
5000 wtppm is preferred, 400-3500 wtppm is more preferred, and 500-2000 wtppm is particularly preferred. If the amount of the suspension stabilizer is less than 300 wt ppm, the resulting vinyl chloride resin particles are likely to be coarse, which is not preferable. On the other hand, if the addition amount is more than 5000 wt ppm, the particles of the obtained vinyl chloride resin become too fine, and foaming becomes severe when unreacted monomers are recovered, which is not practical.

In the present invention, an antioxidant having a vapor pressure at 20 ° C. of 10 ⁻⁶ Pa or less during polymerization and an absorbance of 0.06 or less in an ultraviolet absorption spectrum in a dissolution test described below. Are preferably added and used. The vapor pressure at 20 ° C. of the antioxidant used in the present invention is 10
^-8 Pa or lower is more preferable, and the absorbance is more preferably 0.03 or lower. [Dissolution Test of Antioxidant] In a 300 ml Erlenmeyer flask, 100 ml of deionized water and 5 ml of a methanol solution containing 10 wt ppm of the antioxidant were sterilized at 121 ° C. for 1 hour.
The absorbance of the ultraviolet absorption spectrum at 0 nm is measured.

When the vapor pressure of the antioxidant at 20 ° C. is 10
If the pressure is higher than ^-6 Pa, the antioxidant will evaporate into the air during molding of the resin, and it will not be possible to maintain thermal stability. When the dissolution test is carried out according to the above-mentioned standard, the absorbance of the ultraviolet absorption spectrum of the eluate is undesirably high.
If the absorbance of the ultraviolet absorption spectrum in the above-mentioned dissolution test is larger than 0.06, the antioxidant contained in the product itself is eluted during the dissolution test according to the “Testing Method for Plastic Containers for Infusion (Standards for Pharmaceuticals)”. It seems to be because
It is not preferable because the absorbance of the ultraviolet absorption spectrum of the eluate is increased.

The amount of the antioxidant used in the present invention is preferably from 0 to 1000 wt ppm, and more preferably from 10 to 500 wt ppm, based on the total amount of the vinyl chloride monomer used for the polymerization.
pm is more preferable, and 30 to 300 wt ppm is particularly preferable. If the addition amount of the antioxidant is more than 1000 wt ppm, the absorbance of the ultraviolet absorption spectrum in the dissolution test of the "Plastic container test method (based on local standards)" becomes undesirably high.
The timing and method of adding the antioxidant may be any as long as it is during the polymerization, and the method of addition is not limited.For example, at the end of the polymerization, the plasticizer described in JP-A-63-275653, or hydrophilic. For example, a method in which an antioxidant is dissolved and added to a neutral solvent and a plasticizer is used.

The antioxidants used in the present invention include:
For example, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl) -4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,
2-thio-diethylene-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ,
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-tert-butyl-4-hydroxybenzyl)
Benzene, 2,4-bis- (n-octylthio) 4-hydroxy-3,5-di-tert-butylanilino)
-1,3,5-triazine, N, N'-hexamethylene-bis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-tert-butyl-4 -Hydroxybenzylphosphonate-
Diethyl ester, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol), hexamethylene glycol-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2-thio-
[Diethyl-bis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like, and among them, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-propionate)] 4-hydroxyphenyl) propionate] and 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol) are preferred. These antioxidants are used alone or in combination of two or more.

As the polymerization method of the present invention, an aqueous suspension polymerization method generally used in the art is used. The polymerization conditions are not limited, but the ratio of the vinyl chloride monomer to water is generally 80 to 300 parts by weight of water per 100 parts by weight of the vinyl chloride monomer, and the polymerization temperature is usually 35 to 300 parts by weight.
70 ° C.

As the polymerization initiator used in the present invention, a polymerization initiator usually used for producing a vinyl chloride resin is used, for example, diisopropyl peroxydicarbonate,
Di-2-ethylhexyl peroxy dicarbonate, dilauryl peroxy dicarbonate, dimyristyl peroxy dicarbonate, dicetyl peroxy dicarbonate, ditertiary butyl peroxy dicarbonate, di (ethoxyethyl) peroxy dicarbonate,
Di (methoxyisopropyl) peroxydicarbonate, di (3-methoxybutyl) peroxydicarbonate, di (3-methoxy-3-methylbutyl) peroxydicarbonate, di (butoxyethyl) peroxydicarbonate, di (2 -Isopropoxyethyl) percarbonate such as peroxydicarbonate, dibenzylperoxydicarbonate, dicyclohexylperoxydicarbonate, ditertiarybutylcyclohexylperoxydicarbonate, tertiary butylperoxyneodecanate, amylperoxyneodecaine Nate, tertiary octyl peroxy neodecaneate,
α-cumyl peroxy neodecaneate, tertiary butyl peroxy pivalate, amyl peroxy pivalate, tertiary octyl peroxy pivalate, α-
Peresters such as cumyl peroxypivalate, di-tert-butyl peroxalate, 1,1,3-tetramethylbutyl peroxyphenoxy acetate, lauroyl peroxide, diisobutyl peroxide, 2
Diacyl peroxide such as -ethylhexanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, 2,2'-azobisisobutyronitrile,
Azo compounds such as 2,2'-azobis-2,4-dimethylvaleronitrile and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile are exemplified.

In order to reduce coloring of the molded article, it is preferable to use a combination of peresters. These polymerization initiators are used alone or in combination of two or more. The type and amount of the polymerization initiator are determined depending on the polymerization temperature, the heat removal capability of the polymerization machine (including the heat removal capability of the auxiliary equipment), and the like.
005 to 0.5 parts by weight are suitable.

[0027]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the scope of the present invention is not limited to these examples.

All parts in Examples and Comparative Examples are parts by weight.

Example 1 A partially saponified polyvinyl alcohol (PVK) having a polymerization volume of 7 m ^{3 in} a polymerization machine having a deionized water content of 2500 kg, magnesium oxide of 0.3 kg, a saponification degree of 80 mol% and an average polymerization degree of about 2,000
A) Gohsenol KH manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
Shin-Etsu Chemical Co. as a 5% aqueous solution of 32Kg and hydroxypropylmethylcellulose -17 Co. Metolose
40 kg of a 2% aqueous solution of 60SH-50 , 70% di-2-
0.6 kg of ethylhexyl peroxydicarbonate,
After 0.4 kg of 70% tertiary octyl peroxyneodecaneate was charged and the inside air was removed by a vacuum pump, 2000 kg of vinyl chloride monomer was charged. The polymerization temperature was set to 55 ° C., the reaction was allowed to proceed, and the reaction was continued until the internal pressure reached 5.5 kg / cm ² · G. When the internal pressure reached 5.5 kg / cm ² · G, pentaerythrityl-tetrakis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate]. Thereafter, the unreacted monomer was discharged, and the polymer slurry was dehydrated and dried to obtain 1,680 kg of a vinyl chloride resin as a product. Di-2-ethylhexyl phthalate 50 parts to 100 parts of the obtained polymer,
Blend 8 parts of epoxidized soybean oil, 0.05 parts by weight of zinc stearate, and 0.05 parts of calcium stearate,
After kneading for 2 minutes on a roll at 0 ° C., the sheet was taken out as a sheet having a thickness of 0.6 mm.

The sheet was subjected to an elution test according to the Japanese Pharmacopoeia 10th Edition General Test Method 42 "Plastic container test method for infusion". The amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low and good.

The results are shown in Table 1.

Table 1 also shows the results of the following Examples and Comparative Examples.

Example 2 1670 kg of a product was obtained in the same manner as in Example 1 except that 0.3 kg of magnesium oxide added in Example 1 was replaced with 0.3 kg of hydrotalcite.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out. As a result, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low. there were.

Comparative Example 1 The procedure of Example 1 was repeated, except that 0.3 kg of sodium hydroxide was used instead of 0.3 kg of magnesium oxide added in Example 1, except that the resin became coarse particles and was obtained as a product. Did not.

Comparative Example 2 1670 kg of a product was obtained in the same manner as in Example 1, except that 0.3 kg of sodium hydrogencarbonate was used instead of 0.3 kg of magnesium oxide added in Example 1.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out.
Also, the pH difference from the blank test solution was large.

Comparative Example 3 1670 kg of a product was obtained in the same manner as in Example 1 except that 0.3 kg of zeolite was used instead of 0.3 kg of magnesium oxide added in Example 1.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out.
Also, the pH difference from the blank test solution was large.

Comparative Example 4 Magnesium oxide added in Example 1 was added without adding
1680 Kg of product in the same manner as in Example 1 except that
Obtained.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out.
The pH difference from the blank test solution was also large.

Example 3 The amount of magnesium oxide added in Example 1 was 0.1 kg
1680 Kg of product in the same manner as in Example 1 except that
Obtained.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out. As a result, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low. there were.

Example 4 The amount of magnesium oxide added in Example 1 was 0.8 kg.
1670Kg of product in the same manner as in Example 1 except that
Obtained.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out. As a result, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low. there were.

Example 5 The amount of magnesium oxide added in Example 1 was 1.5 kg.
1660 Kg of product in the same manner as in Example 1 except that
Obtained. A roll sheet was obtained in the same manner as in Example 1,
Slightly colored pink. Further, when an eluate test was conducted, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low and good.

Example 6 The same procedure as in Example 1 was repeated except that 0.3 kg of the magnesium oxide added in Example 1 was added when the conversion of the vinyl chloride monomer was 20%.
Obtained.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out. As a result, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low. there were.

Example 7 1670 kg of a product was prepared in the same manner as in Example 1 except that 0.3 kg of magnesium oxide added in Example 1 was added when the conversion of the vinyl chloride monomer was 40%.
Obtained.

When a roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out, the amount of zinc eluted was small.
The pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low and good.

Comparative Example 5 The di-2 of Example 1 was added to 100 parts of the product obtained in Comparative Example 4.
A roll sheet was obtained in the same manner as in Example 1 by adding 0.015 part of magnesium oxide at the time of blending ethylhexyl phthalate and the like, and a dissolution test was carried out. The difference was great.

Comparative Example 6 A suspension stabilizer was prepared by using a saponification degree of 80 mol and an average polymerization degree of about 2,000.
Nippon Gohsei as a partially saponified polyvinyl alcohol
48% 5% aqueous solution of Gohsenol KH-17 manufactured by Sangyo Co., Ltd.
Except that only g was used, the procedure was the same as in Example 1, but the resin became coarse particles and could not be obtained as a product.

Comparative Example 7 A suspension stabilizer was prepared using hydroxypropyl methylcellulose .
Example 1 was repeated except that only 2 kg of a 2% aqueous solution of Metroose 60SH-50 manufactured by Shin-Etsu Chemical Co., Ltd. was used.
In addition, the resin became coarse particles and fine powder particles, and was not obtained as a product.

Example 8 In Example 1, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-)-4-added when the internal pressure reached 5.5 kg / cm ² · G. Hydroxyphenyl) propionate] instead of octadecyl-3-
(3,5-di-t-butyl-4-hydroxyphenyl)
1680 Kg of a product was obtained in the same manner as in Example 1 except that propionate was used.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out. As a result, the amount of zinc eluted was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low. there were.

Example 9 In Example 1, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-) was added when the internal pressure reached 5.5 kg / cm ² · G. 1680 kg of a product was obtained in the same manner as in Example 1 except that the amount of [ hydroxyphenyl) propionate] was changed to 1.00 kg.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was carried out.
Although the pH difference from the blank test solution was small, the absorbance in the ultraviolet absorption spectrum was slightly higher.

[0058]

[Table 1]

[0059]

EFFECT OF THE INVENTION The vinyl chloride resin product obtained by this method has a small amount of magnesium oxide and / or hydrotalcite added, and a small amount of zinc eluted in an elution test specified in the Japanese Pharmacopoeia. In addition, the absorbance of the ultraviolet absorption spectrum is low, and the pH difference from the blank test solution is small,
Very suitable for medical use.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 2/18-2/20

Claims (6)

(57) [Claims] 1. A method for producing a vinyl chloride resin by aqueous suspension polymerization of vinyl chloride, wherein magnesium oxide and / or hydrotalcite are added during polymerization, and polyvinyl alcohol and a cellulose derivative are used in combination as a suspension stabilizer. A method for producing a vinyl chloride resin. 2. The method for producing a vinyl chloride resin according to claim 1, wherein the magnesium oxide and / or hydrotalcite are added until the conversion of the vinyl chloride monomer becomes 50% by weight. 3. The process for producing a vinyl chloride resin according to claim 1, wherein the amount of magnesium oxide and / or hydrotalcite is 10 to 1000 wt ppm based on the total amount of the vinyl chloride monomer used for the polymerization. 4. The addition amount of the suspension stabilizer is 300 to 5000 wt.
4. The method for producing a vinyl chloride resin according to claim 1, wherein the dispersion stabilizer is pm, and the polyvinyl alcohol in the suspension stabilizer is 95 to 10% by weight. 5. The polymerization method according to claim 1, wherein the vapor pressure at 20.degree.
^{5. The} method for producing a vinyl chloride resin according to claim 1, wherein an antioxidant having a pressure of ^-6 Pa or less and an absorbance in an ultraviolet absorption spectrum of 0.06 or less in a dissolution test is added. 6. The vinyl chloride according to claim 1, 2, 3, 4 or 5, wherein at least a zinc metal soap-based stabilizer is added to a vinyl chloride resin obtained by aqueous suspension polymerization of vinyl chloride. Method of manufacturing resin.