JPH05170806A - Production of vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain the title resin containing a smaller amount of MgO and/or hydrotalcite and suited for medical use by performing the aqueous suspension polymerization of vinyl chloride in the presence of MgO and/or hydrotalcite and a suspension stabilizer comprising two specified compounds. CONSTITUTION:The title process comprises performing the aqueous polymerization of vinyl chloride, wherein MgO and/or hydrotalcite is added during the polymerization and the suspension stabilizer used comprises a combination of PVA and a cellulose derivative. The obtained vinyl chloride resin contains a smaller amount of MgO and/or hydrotalcite, has a smaller amount of zinc leached out when tested by the leaching test specified in the Pharmacopoeia of Japan, a low absorbance in UV absorption spectrum and has a pH differing little from that of a blank test solution and is very suitable for medical use.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a vinyl chloride resin suitable for medical use.

[0002]

BACKGROUND OF THE INVENTION As a vinyl chloride resin used for medical purposes, a vinyl chloride resin produced by aqueous suspension polymerization is usually used, and a vinyl chloride resin generally known as a non-toxic compound is used as the vinyl chloride resin. 2-Ethylhexyl phthalate, calcium and zinc metal soap stabilizers, epoxidized soybean oil, lubricants, etc. are added, compounded, and molded, and then the Japanese Pharmacopoeia 10th Revised General Test Method 42 “Plastic Container for Infusion Test Method Standard) ”, etc., and the eluate test is performed.

As a composition, 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 is disclosed in JP-B-58-17625. It is shown.

Further, Japanese Examined Patent Publication No. 61-46492 discloses a medical vinyl chloride resin composition prepared by blending at least one metal oxide such as magnesium oxide and used for radiation sterilization. Considering the influence on the human body, the elution amount of the additive needs to be a very low value.

[0005]

However, there are problems that a product obtained by non-toxic compounding with a general vinyl chloride resin has a large zinc elution amount and a large pH difference (ΔpH) between the test solution and the blank test solution. Yes Improvement is desired. This is because zinc metal soap is used in the non-toxic formulation that is generally said to be the stabilizer system with the least harm to the human body, and part of it is eluted in the elution test.

Further, since the non-toxic formulation is inferior in thermal stability to other formulations, thermal deterioration is apt to occur during molding, and its dehydrochlorination is Δ.
It is believed to increase the pH difference.

[0007]

The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and have completed the present invention.

That is, the present invention is a method for producing a vinyl chloride resin by aqueous suspension polymerization of vinyl chloride, wherein magnesium oxide and / or hydrotalcite is 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 together.

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

It is not clear why the elution amount of zinc is reduced and ΔpH is reduced by adding magnesium oxide and / or hydrotalcite at the time of polymerization. Neutralizes the attached HCl, which reduces the amount of zinc elution,
It seems that ΔpH becomes smaller.

When the magnesium oxide and / or hydrotalcite is added, the conversion rate 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 the polymerization.
When the conversion is added in excess of 50% by weight, the effect of decreasing the zinc elution amount is small and ΔpH is large, which is not preferable.

The addition amount of magnesium oxide and / or hydrotalcite is preferably 10 to 1000 wtppm with respect to the total amount of vinyl chloride monomer charged for polymerization, and 20 to 1000 wtppm is preferable.
500 wt ppm is more preferable, and 40 to 300 wt ppm is particularly preferable. If the amount added exceeds 1000 wt ppm, the resulting vinyl chloride resin particles are likely to become coarse, and coloring after molding is unfavorable. On the other hand, if the addition amount is less than 10 wt ppm, the effect of suppressing zinc elution and the effect of pH fluctuation is unfavorably low.

The magnesium oxide and hydrotalcite used in the present invention may be those generally commercially available, but it is more preferable to use those for food additives.

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

Examples of polyvinyl alcohol include completely saponified or partially saponified polyvinyl alcohol. The saponification degree of polyvinyl alcohol is preferably 60 to 99 mol%, more preferably 65 to 95 mol%,
0 to 85 mol% is particularly preferable. If the degree of saponification is lower than 60 mol% or higher than 99 mol%, it is considered that the protective colloid property is low, but the particles of the obtained vinyl chloride resin are likely to become coarse, which is not preferable.

The degree of polymerization of the polyvinyl alcohol used in the present invention is preferably 200 to 3500, and 500 to 300.
0 is more preferable, and 600 to 2500 is particularly preferable.
When polyvinyl alcohol having a degree of polymerization of less than 200 is used, the protective colloid property is low, and the resulting vinyl chloride resin particles tend to be coarse, which is not preferable. Degree of polymerization is 3
When polyvinyl alcohol higher than 500 is used, it is difficult to dissolve the polyvinyl alcohol in water and the viscosity of the aqueous solution becomes high, which is not suitable for practical use. Polyvinyl alcohol can be used alone or in combination of two or more kinds.

Examples of the cellulose derivative include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose and the like, and hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose are preferable. 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 wt% or lower than 10 wt%, the obtained polyvinyl chloride resin particles tend to be coarse, which is not preferable.

The suspension stabilizer used in the present invention is added in an amount of 300 to 300 with respect to the total amount of vinyl chloride monomer charged to the polymerization.
5000 wtppm is preferable, 400 to 3500 wtppm is more preferable, and 500 to 2000 wtppm is particularly preferable. If the amount of the suspension stabilizer added is less than 300 wt ppm, the obtained vinyl chloride resin particles tend to be coarse, which is not preferable. On the other hand, if the addition amount is more than 5000 wt ppm, the obtained vinyl chloride resin particles become too fine and foaming becomes severe when recovering the unreacted monomer, which is not practical.

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

The vapor pressure of the antioxidant at 20 ° C. is 10
If it is higher than ^-6 Pa, it is considered that the antioxidant evaporates into the atmosphere during molding of the resin, heat stability cannot be maintained, and dehydrochlorination proceeds. If the elution test is performed according to the "standard"), the absorbance of the ultraviolet absorption spectrum of the eluate becomes high, which is not preferable.
If the absorbance of the ultraviolet absorption spectrum in the above dissolution test is greater than 0.06, the antioxidant contained in the product itself will elute during the dissolution test of "Plastic container test method for infusion (Pharmacopoeia standard)". It seems to be because
The ultraviolet absorption spectrum of the eluate has a high absorbance, which is not preferable.

The amount of the antioxidant used in the present invention is preferably 0 to 1000 wtppm, and preferably 10 to 500 wtp, based on the total amount of vinyl chloride monomer used for the polymerization.
pm is more preferable, and 30 to 300 wtppm is particularly preferable. If the amount of the antioxidant added is more than 1000 wt ppm, the absorbance of the ultraviolet absorption spectrum becomes high in the elution test of "Plastic container test method (Pharmacopoeia standard)", which is not preferable.
The timing and the addition method of the antioxidant may be during polymerization, and there is no limitation on the addition method, for example, at the end of the polymerization, a plasticizer described in JP-A-63-275653, or a hydrophilic agent. A method in which an antioxidant is dissolved in a solvent and a plasticizer and added is used.

The antioxidant used in the present invention includes:
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-hydrocinnamide), 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-tertiarybutyl-4-hydroxyphenyl) propionate] and the like can be mentioned. Among them, pentaerythrityl-tetrakis [3- (3,5-di-tertiarybutyl- 4-hydroxyphenyl) propionate], 4,4′-butylidene-bis (3-methyl-6-tertiarybutylphenol) are preferred. These antioxidants may be 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 vinyl chloride monomer to water is generally 80 to 300 parts by weight of water to 100 parts by weight of vinyl chloride monomer, and the polymerization temperature is usually 35 to 35 parts by weight.
It is 70 ° C.

As the polymerization initiator used in the present invention, a polymerization initiator usually used in the production of vinyl chloride resin is used, for example, diisopropyl peroxydicarbonate,
Di-2-ethylhexyl peroxydicarbonate, dilauryl peroxydicarbonate, dimyristyl peroxydicarbonate, dicetyl peroxydicarbonate, ditertiary butyl peroxydicarbonate, di (ethoxyethyl) peroxydicarbonate,
Di (methoxyisopropyl) peroxydicarbonate, di (3-methoxybutyl) peroxydicarbonate, di (3-methoxy-3-methylbutyl) peroxydicarbonate, di (butoxyethyl) peroxydicarbonate, di (2 -Isopropoxyethyl) peroxydicarbonate, dibenzyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, percarbonate such as ditertiary butyl cyclohexyl peroxydicarbonate, tertiary butyl peroxyneodecanate, amylperoxyneodeca Nate, tertiary octyl peroxy neodecaneate,
α-cumylperoxy neodecanoate, tertiary butyl peroxypivalate, amyl peroxypivalate, tertiary octyl peroxypivalate, α-
Cumyl peroxypivalate, ditertiary butyl peroxalate, peresters such as 1,1,3-tetramethylbutyl peroxyphenoxyacetate, lauroyl peroxide, diisobutyl peroxide, 2
-Diacyl peroxide such as ethylhexanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, 2,2'-azobisisobutyronitrile,
Examples of the azo compound include 2,2′-azobis-2,4-dimethylvaleronitrile and 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile.

In order to reduce the coloring of the molded product, it is preferable to use perester in combination. 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 capacity of the polymerization machine (including the heat removal capacity of incidental equipment), and the like, but usually 0.
005 to 0.5 parts by weight is suitable.

[0027]

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

All parts in the examples and comparative examples are parts by weight.

Example 1 Internal volume 7 m³ 2500 kg of deionized water in a polymerization machine, oxidation
Average polymerization of 0.3 kg magnesium and 80 mol% saponification degree
Partially saponified polyvinyl alcohol (PV
32 kg of 5% aqueous solution of A) and hydroxypropylmethyi
L-cellulose 2% aqueous solution 40 kg, 70% di-2-ethyl
Luhexyl peroxydicarbonate 0.6 kg, 70
% Tertiary Octyl Peroxyneodecanoate 0.
4 kg was charged and the air inside was removed by a vacuum pump.
Then, 2000 kg of vinyl chloride monomer was charged. polymerization
The temperature is set to 55 ° C, the reaction is allowed to proceed, and the internal pressure
Is 5.5 Kg / cm² ・ The reaction was continued until G was reached.
Internal pressure is 5.5 Kg / cm ² ・ When reaching G
And pentaerythrityl-tetrakis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propione
0.2 kg was charged. After that, unreacted monomer
Discharge, dehydrate the polymer slurry and dry it as a product.
1680 kg of vinyl chloride resin was obtained. Polymer obtained
50 parts of di-2-ethylhexyl phthalate in 100 parts,
8 parts epoxidized soybean oil, 0.05 part zinc stearate,
Blended with 0.05 part calcium stearate, 170 ℃
A sheet with a thickness of 0.6 mm after being kneaded for 2 minutes on a roll
I took it out as.

The sheet was subjected to an eluate test in accordance with the Japanese Pharmacopoeia 10th revised general test method 42 "Plastic container test method for infusion". The zinc elution amount was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low, which was 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 hydrotalcite 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. As a result, the zinc elution amount was small, the pH difference from the blank test solution was small, and the absorbance in the ultraviolet absorption spectrum was low and good. there were.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 0.3 kg of magnesium oxide added in Example 1 was replaced by 0.3 kg of sodium hydroxide, but the resin became coarse particles and was obtained as a product. There wasn't.

Comparative 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 by 0.3 kg of sodium hydrogen carbonate.

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

Comparative Example 4 Magnesium oxide added in Example 1 was added without addition.
1680 kg 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 conducted.
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 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 zinc elution amount was small, the pH difference from the blank test solution was small, and the absorbance in the ultraviolet absorption spectrum was low, indicating good results. there were.

Example 4 The amount of magnesium oxide added in Example 1 was 0.6 kg.
1670 kg 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 zinc elution amount was small, the pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low and good. there were.

Example 5 The amount of magnesium oxide added in Example 1 was 1.5 kg.
1660 kg in the same manner as in Example 1 except that
Obtained. A roll sheet was obtained in the same manner as in Example 1,
Colored slightly pink. Furthermore, when an eluate test was conducted, the amount of zinc elution 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 1680 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 vinyl chloride monomer was 20%.
Obtained.

When a roll sheet was obtained in the same manner as in Example 1 and an eluate test was conducted, the zinc elution amount was small, the pH difference with the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low and good. 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 vinyl chloride monomer was 40%.
Obtained.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was conducted.
The pH difference from the blank test solution was small, and the absorbance of the ultraviolet absorption spectrum was low, which was good.

Comparative Example 5 100 parts of the product obtained in Comparative Example 4 was added to the di-2 of Example 1.
When 0.015 parts of magnesium oxide was added at the time of compounding ethylhexyl phthalate or the like and a roll sheet was obtained in the same manner as in Example 1, and an eluate test was conducted, a large amount of zinc was eluted, and a pH with a blank test solution was obtained. The difference was great.

Comparative Example 6 A suspension stabilizer having a saponification degree of 80 mol% and an average degree of polymerization of about 200 was used.
0% 5% aqueous solution of partially saponified polyvinyl alcohol 48K
The procedure was the same as in Example 1 except that only g was used, but the resin became coarse particles and could not be obtained as a product.

Comparative Example 7 A suspension stabilizer was hydroxypropylmethylcellulose 2
% Aqueous solution of only 120 kg, but the same as in Example 1, except that unreacted monomer is blown up, and
The resin became coarse particles and fine powder particles and could not be obtained as a product.

Example 8 In Example 1, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-) was 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 conducted. As a result, the zinc elution amount was small, the pH difference from the blank test solution was small, and the absorbance in the ultraviolet absorption spectrum was low, indicating good results. there were.

Example 9 Pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-) added in Example 1 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 0.84 Kg.

A roll sheet was obtained in the same manner as in Example 1 and an eluate test was conducted.
The pH difference from the blank test solution was also small, but the absorbance in the ultraviolet absorption spectrum was slightly high.

[0058]

[Table 1]

[0059]

The vinyl chloride resin product obtained by this method has a small amount of added magnesium oxide and / or hydrotalcite, and a small amount of zinc eluted in the eluate test specified by the Japanese Pharmacopoeia. Also, the absorbance of the ultraviolet absorption spectrum is low, and the pH difference with the blank test solution is small
Very suitable for medical use.

Claims (6)

[Claims] 1. A method for producing a vinyl chloride resin by aqueous suspension polymerization of vinyl chloride, which comprises adding magnesium oxide and / or hydrotalcite at the time of polymerization, and using polyvinyl alcohol and a cellulose derivative as a suspension stabilizer in combination. A method for producing a vinyl chloride resin, comprising: 2. The method for producing a vinyl chloride resin according to claim 1, wherein magnesium oxide and / or hydrotalcite is added until the conversion of the vinyl chloride monomer reaches 50% by weight. 3. The method for producing a vinyl chloride resin according to claim 1, wherein the added amount of magnesium oxide and / or hydrotalcite is 10 to 1000 wtppm with respect to the total charged amount of vinyl chloride monomer used for the polymerization. 4. The amount of suspension stabilizer added is 300 to 5000 wt p based on the total amount of vinyl chloride monomer charged to the polymerization.
4. The method for producing a vinyl chloride resin according to claim 1, 2 or 3, wherein the suspension stabilizer has a polyvinyl alcohol content of 95 to 10 wt%. 5. The vapor pressure at 20 ° C. during polymerization is 10
^{5. The} method for producing a vinyl chloride resin according to claim 1, 2, 3 or 4, wherein an antioxidant having an absorbance of ^-6 Pa or less and having an ultraviolet absorption spectrum of 0.06 or less in an elution test is added. 6. The vinyl chloride according to claim 1, 2, 3, 4 or 5, which is used by adding at least a zinc metal soap stabilizer to a vinyl chloride resin obtained by an aqueous suspension polymerization of vinyl chloride. Resin manufacturing method.