JPH0333146A - Polyvinyl chloride resin material for gamma-ray sterilization - Google Patents

Abstract

PURPOSE:To prepare a polyvinyl chloride resin material having a high resistance to gamma radiation and useful as the raw material of a medical tool by polymerizing vinyl chloride or a mixture of vinyl chloride with a monomer copolymerizable therewith in the presence of a specific polymn. initiator under a specific condition. CONSTITUTION:Vinyl chloride or a mixture of vinyl chloride with a monomer copolymerizable therewith is polymerized at 50 deg.C or lower in the presence of a peroxyester polymn. initiator having a 10-hr half life temp. of 50 deg.C or lower to a conversion of 80wt.% to produce a polyvinyl chloride resin, which is used as a main component of a resin material for gamma-ray sterilization. Examples of the copolymerizable monomers are vinyl acetate, alkyl vinyl ether, vinylidene chloride, (meth)acrylic acid and an ester thereof. Examples of the polymn. initiator are t-butyl peroxyneodecanoate and cumyl peroxyneodecanoate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a vinyl chloride resin material that is a material for medical devices.

In particular, the present invention relates to a vinyl chloride-based super fat material that is resistant to discoloration even when irradiated with T-rays, that is, has high gamma ray resistance.

(Prior Art) Ethylene oxide gas has been used as a method for sterilizing medical instruments, but there are problems with its residual and toxicity, so rH pre-irradiation has come to be used instead.

Although there are various medical devices made of vinyl chloride resin, vinyl chloride resin has the disadvantage of discoloration due to rllA irradiation.

As a countermeasure against this, Japanese Patent Application Laid-Open Nos. 52-3653, 61-240959, and 62-235347 have been proposed.
No. 64-66260 discloses a method of mixing various additives and resins.

Further, JP-A-64-87650 discloses the use of copolymerization of vinyl chloride and α-olefin.

<Problem to be solved by the invention> When various additives are mixed with vinyl chloride resin, their types and amounts are limited due to the effects on the human body due to their elution from medical devices, and the amount of additives that are lost due to elution is limited. However, the sustainability of the effect is still not sufficient.

In addition, the copolymer of vinyl chloride and α-olefin as disclosed in JP-A-64-87650 is difficult to obtain with a high degree of polymerization and requires a large amount of polymerization initiator, making it difficult to obtain from an industrial standpoint. There is a.

Ku! Means for Solving Problem I> The present invention provides a method for using a vinyl chloride monomer or a mixture of other monomers copolymerizable therewith with a 10-hour half-life temperature of so
In the presence of a peroxyester polymerization initiator of 'c or less,
This is a vinyl chloride resin material for T-ray irradiation sterilization, which is mainly composed of a vinyl chloride resin obtained by polymerizing to a polymerization yield of 80% by weight at a temperature not exceeding 50°C.

Other monomers copolymerizable with vinyl chloride used in the present invention include vinyl acetate, vinyl propionate, saturated fatty acid vinyl, alkyl vinyl ether, vinylidene chloride, unsaturated monocarboxylic acid such as (meth)acrylic acid, etc. Examples include acids and their esters, unsaturated dicarboxylic acids such as maleic acid and fumaric acid, and their esters.

Examples of peroxyester polymerization initiators with a 10-hour half-life temperature of 50°C or less include t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate, 2-4
-4) Peroxy esters such as lymethylpentylperoxy-2-neodecanoate, -hexylperoxyneodecanoate, and rhubarboxyneohexanoate are suitable.

The types and amounts of these are determined depending on the polymerization temperature and polymerization time.

In other words, the lower the 10-hour half-life temperature is, the lower the polymerization temperature is, and if the amount is increased, the polymerization time can be shortened, but since the amount of heat generated also increases, it is limited by the heat removal ability.

If the polymerization temperature exceeds 50° C., the gamma ray resistance decreases, which is not preferable.

A well-known chain transfer agent may be used to appropriately adjust the degree of polymerization of the resulting resin.

The polymerization yield is 80% by weight or less.

The higher the content exceeds 80% by weight, the lower the gamma ray resistance becomes.

Termination of polymerization may be carried out by a known method such as removing unreacted monopolymers from the polymerization site or adding an antioxidant or a polymerization inhibitor.

The polymerization reaction can be carried out by any of the well-known methods such as suspension polymerization, bulk polymerization, and emulsion polymerization, among which bulk polymerization and suspension polymerization are preferred.

The vinyl chloride resin thus obtained has high gamma ray resistance.

In order to make the vinyl chloride resin into a material that can be processed into, for example, medical equipment, a plasticizer and a stabilizer are added.

Examples of the plasticizer include alkyl esters of aromatic polybasic acids such as dibutyl phthalate and dioctyl phthalate; alkyl esters of aliphatic polybasic acids such as dioctyl adipate, and the like.

This plasticizer is used to soften the vinyl chloride resin, and its amount varies depending on the type and shape of the molded article, but is generally 15 to 150 parts by weight per 100 parts by weight of the vinyl chloride resin.

Other medical uses include 3 to 15 parts by weight of epoxy plasticizers such as epoxidized soybean oil and epoxy linseed oil, and calcium of higher fatty acids such as calcium stearate, calcium laurate, zinc stearate, and zinc palate. and 0.2 to 5 parts by weight of a Ca-Zn stabilizer made from a zinc salt.

(Effects of the Invention) The vinyl chloride resin material of the present invention is suitable for use in acid form processing for medical instruments and sterilization by T-ray irradiation.

In other words, it is stable against T-ray irradiation, has little discoloration, and can be used for a long period of time.

<Examples> Example 1 In a 1001 autoclave, 451 g of deionized water, 30 g of partially saponified polyvinyl alcohol having a degree of saponification of 80 mol% and an average degree of polymerization of 2000, and z, 4. After charging 8 g of 4-trimethylpentylperoxy-2-neodecanoate and deaerating the inside of the autoclave to 30 mmHg to remove oxygen, 30 kg of vinyl chloride monomer was charged and the temperature was raised to 48°C while stirring. , started polymerization.

The pressure inside the autoclave at the start of polymerization is 0.2 from the initial level.
When the temperature drops to Kg/cd, 7z/-43g of 2,6-t-butyl 4)f is added to stop the polymerization, the unreacted vinyl chloride monomer is purged, the contents are taken out, and dehydrated. Dry.

The polymerization yield was 78% by weight.

To 100 parts by weight of the obtained vinyl chloride resin, 30 parts by weight of dioctyl phthalate, 10 parts by weight of epoxidized soybean oil, 0.3 parts by weight of calcium stearate, and 0 parts by weight of zinc stearate.
．． 3 parts by weight was added, kneaded using a roll at 160°C to form a sheet, and further pressed at 170°C to form a sheet with a thickness of l.
+u sheet.

To this sheet, 2.5
It was irradiated with Mrad and 5 Mrad.

Changes in color tone were measured using a color difference meter manufactured by Nippon Heavy Industries Co., Ltd.
This was confirmed by measuring 0-Indafukus (Y, I).

Changes in tensile properties were measured by measuring elongation at break in accordance with JIS-6734, and values were shown with the value without γ-ray irradiation set as 100.

The results are shown in Table 1.

Example 2 Except that the polymerization temperature was 43°C, the amount of initiator was 10 g, and 7 g of 2-mercaptoethanol was used as a chain transfer agent.
The same operation as in Example 1 was performed, the polymerization was stopped at a polymerization yield of 80% by weight, and a vinyl chloride resin was obtained.

Evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 The polymerization temperature was set to 55°C, 8 g of diisopropyl peroxydicarbonate was used as an initiator, and the polymerization was stopped when the pressure inside the autoclave decreased by 3.5 kg/cj from the initial stage.The following steps were the same as in Example 1. A vinyl chloride resin was obtained with a polymerization yield of 91% by weight.

Evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 Example 3.4 Comparative Examples 2 to 5 In Example 1, the polymerization temperature, type and amount of initiator, and polymerization termination timing (pressure value decreased from the initial pressure) were as shown in Table 2. A vinyl chloride resin was obtained by carrying out the same operation except that

Polymerization yields are shown in Table 2.

The obtained vinyl chloride resin was evaluated for change in color tone in the same manner as in Example 1.

The results are shown in Table 3.

Table 2 BND; CND.

BP.

TMPND; t-butyl peroxyneodacano I-tocumylperoquine neoobanoate t-butyl peroxypyrate 2.4.4-trimethylpentyroquinoneo9kaino I-to OPD.

Claims (1)

[Claims] (1) Vinyl chloride monomer or a mixture of other monomers copolymerizable with it is heated at 50°C in the presence of a peroxyester polymerization initiator with a 10-hour half-life temperature of 50°C or less.
A vinyl chloride resin material for sterilization by gamma ray irradiation, which is mainly composed of a vinyl chloride resin obtained by polymerizing to a polymerization yield of 80% by weight at a temperature not exceeding .