JPH02209151A - Resin composition for medical implement and material - Google Patents

Abstract

PURPOSE:To obtain the resin compsn. for medical implements an materials having resilience, transparency, heat resistance, and mechanical properties, such as autoclave resistance, by consisting the resin compsn. of a vinyl chloride/ ethylene copolymer and an ethylene/carbon monoxide/alkyl (meth)acrylate ternary copolymer. CONSTITUTION:The resin compsn. for medical implements and materials consists of the vinyl chloride/ethylene copolymer and the ethylene/carbon monoxide/alkyl (meth)acrylate ternary copolymer. The ethylene content of the vinyl chloride/ ethylene copolymer is in a 1.0 to 8.0wt.%. The compsn. having the sufficient transparency is hardly obtainable if the ethylene content is below 1.0. Deformation and adhesion are liable to arise with a blood bag requiring sterilization in an autoclave if the content exceeds 8.0. The melt index of the ethylene/carbon monoxide/alkyl (meth)acrylate copolymer is >=5dg/min and the structural viscosity index is <=1.5. The sufficient transparency is not obtd. with the molding of this compsn. in some cases, if none of these conditions are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a resin composition suitable for constructing medical equipment, particularly infusion storage bags, blood storage containers, tubes for blood circuits of artificial kidneys, and the like.

(Prior Art) Conventionally, blood bags, blood tubes, etc. for transporting and storing blood, for example, have been made from compositions in which dioctyl phthalate is added as a plasticizer to vinyl chloride resin.

Blood bags, blood tubes, etc. obtained from this composition are excellent in terms of flexibility and transparency, but the drawback is that dioctyl phthalate elutes in small amounts and is absorbed and accumulated in the body through the blood. Therefore, there was a need to create a resin composition for constructing blood bags and blood circuit tubes that does not have these drawbacks.

Ethylene/carbon monoxide/
It has been found that a terpolymer of vinyl acetate is effective.

They then actually mixed this terpolymer with vinyl chloride resin to create a homogeneous composition, and investigated the properties of this composition. As a result, although satisfactory results were obtained in terms of transparency and flexibility, it was found that it gave unfavorable results in hemolysis and cytotoxicity tests.

Therefore, the present inventors further investigated the cause and found that acetic acid produced by the decomposition of this copolymer is present in the ethylene/carbon monoxide/vinyl acetate copolymer, and the resin composition It has been found that when molded into medical equipment, it causes hemolysis and cytotoxicity.

(Problem to be solved by the invention) Therefore, based on this knowledge, the present inventors have
No. 116569 (Japanese Unexamined Patent Publication No. 56-41240) discloses a resin composition for medical equipment in which a predetermined amount of ethylene/carbon monoxide/vinyl acetate copolymer and fine powder of calcium oxide or magnesium oxide is blended with a vinyl chloride resin. proposed.

However, if the amount of acetic acid generated in the ethylene/carbon monoxide/vinyl acetate copolymer is extremely small, it can be captured by fine powder of calcium oxide or magnesium oxide in the composition; If there is a large amount of acetic acid, it will not be able to be captured by the fine powder of calcium oxide or magnesium oxide in the composition, and it is inevitable that molded products made from the composition will have hemolytic properties and cytotoxicity. Therefore, if the amount of calcium oxide or magnesium oxide fine powder in the composition is increased, the transparency of the molded product processed therefrom will decrease, the ignition residue will increase, and the standard value for medical devices will be exceeded. There is a risk that this will happen.

The present invention eliminates the drawbacks of the prior art such as ridges, eliminates the elution of plasticizer and desorption of acetic acid, and has flexibility, transparency, heat resistance, and autoclave resistance equivalent to or higher than that of the resin composition of the prior art. The purpose of this invention is to provide a resin composition for medical equipment that has mechanical properties such as elasticity.

(Means for solving the problems) The present invention has the following features:1. 2. A resin composition for medical equipment comprising a vinyl chloride/ethylene copolymer and an ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer; and 2. The resin composition for medical equipment according to claim 1, wherein the vinyl chloride/ethylene copolymer has an ethylene content in the range of 1°0 to 8.0% by weight, and 3° ethylene/monoxide. The melt index of carbon/(meth)acrylic acid alkyl ester copolymer is 5.
dg/min or more and a structural viscosity index of 1.5 or less.

The vinyl chloride/ethylene copolymer used in the present invention has an ethylene content of 1.0 to 8.0 based on the weight of the copolymer.
%, and if it is less than 1.0, it may be difficult to obtain a molded article with sufficient transparency when the composition is used as a raw material. When you cross it,
Molded products, especially blood bags that require sterilization in an autoclave at 121° C. for about 20 minutes, are susceptible to deformation and adhesion.

In addition, the average degree of polymerization of vinyl chloride/ethylene copolymer is 70
A degree of polymerization of 0 or more is preferable, and if the degree of polymerization is less than 700, problems such as decreased mechanical durability of the resulting resin composition, such as creep, and surface stickiness may occur, although it depends on the amount of blending. In addition, heat resistance is also reduced, and there is a risk that thermal decomposition products that have a toxic effect on living organisms may be generated during melt processing.

The vinyl chloride/ethylene copolymer on the ridges can be produced by a suspension polymerization method or an emulsion polymerization method using an ordinary radical polymerization catalyst. For example, one specific polymerization method is as follows.

After adding water and a dispersant to an autoclave equipped with a stirrer, vacuum suction is applied to remove oxygen present in the autoclave. Next, vinyl chloride and ethylene are added while stirring, then the pressure is maintained, a polymerization initiator is added, and the temperature is raised to 40°C to 70°C while stirring is continued. 5 at this temperature
Polymerization proceeds during stirring for 15 hours.

As the dispersant, surfactants such as partially saponified polyvinyl alcohols, methylcellulose, hydroxymethylcellulose, and carboxymethylcellulose can be used.

The type of polymerization initiator to be added differs depending on whether suspension polymerization or emulsion polymerization is performed.

To carry out suspension polymerization, diisobutyryl peroxide,
Di-2-methylpentanoyl peroxide, 3.5.
5-1 Peroxide compounds such as trimethylhexanoyl peroxide, lauroyl peroxide, and benzoyl peroxide, perester compounds such as cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, dicetyl peroxydicarbonate, and Peroxydicarbonate compounds such as 2-ethylhexyl peroxydicarbonate and diisobutyl peroxydicarbonate are used.

For emulsion polymerization, ammonium persulfate, potassium persulfate, etc. are used. These polymerization initiators should be added in an amount of 0.02 to 0.3 based on the total amount of vinyl chloride and ethylene.
It is used in proportions of % by weight.

In addition, vinyl chloride and ethylene are added to the reaction system in excess of 5 to 50% by weight relative to the weight of the polymer to be obtained.0 The weight ratio of the total amount of vinyl chloride and ethylene used during polymerization to the water used specifically for polymerization is A ratio of 1:1.2 to 1:3 is selected.

After the polymerization is completed, unreacted monomers are removed, and the suspension or emulsion in the autoclave is filtered to remove water to obtain polymer particles.Then, the polymer particles are washed with water and dried.

The ethylene/carbon monoxide/(meth)acrylic acid alkyl ester copolymer in the present invention is the vinyl chloride/(meth)acrylic acid alkyl ester copolymer described above.
It plays a role as a plasticizer for ethylene copolymers, and the alkyl group in the (meth)acrylic acid alkyl ester is linear or branched,
Its carbon number is 1 to 18, specifically methyl group 1.
n-propyl group, isopropyl group, n-butyl group, 5e
Examples include c-butyl group, t-butyl group, isobutyl group, hexyl group, octyl group, and among these, those having 2 to 2 carbon atoms
6 is preferred. This ethylene is 40-80% by weight
, preferably in an amount of 60-70% by weight, carbon monoxide
(meth)acrylic acid alkyl ester in an amount of ~20% by weight, preferably 5-15% by weight, 20-40% by weight,
The content is preferably 20 to 35% by weight, and other monomers may be copolymerized if necessary.

Therefore, the ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer of the present invention has a melt index of 5 dg/min or more and a structural viscosity index of 1. A value of 5 or less is preferable, and if neither of these conditions is satisfied, the molded product may not have sufficient transparency.

The structural viscosity index (hereinafter referred to as "N value") referred to in the present invention is a value that indicates the characteristics of the melt viscosity of a resin, and its measurement method is as follows:
Page 15 of “Research and summary edition on the processability of vinyl chloride resin; edited and published by the Vinyl Chloride Association, October 1964,”
It is described in ``3. Analysis method of flow characteristics'' and can be measured using a conventional flow tester or capillary rheometer.When the relationship between shear rate and shear stress is plotted on a log-log graph, the slope of the straight line is It can be found by

For Newtonian fluids, the N value is 1.0, and the greater the non-Newtonianity, the greater the N value becomes greater than 1.0.

In order to produce such an ethylene/carbon monoxide/alkyl (meth)acrylic acid terpolymer, each of the monomers ethylene, carbon monoxide, and alkyl (meth)acrylic acid ester is combined with a catalyst. t-butylperoxyisobutyrate or azodiisobutyronitrile, etc., at a predetermined ratio into a high-speed stirring reaction vessel, mixed, and heated at high temperature (160 to 230°C) under high pressure (240°C).
The monomers may be copolymerized by stirring at high speed (00 to 27,000 ps i). A copolymer having an N value of less than 1.5 can be obtained, for example, by adding the (meth)acrylic acid alkyl ester monomer in portions, that is, by dividing a predetermined amount of the monomer into several portions and mixing them.

In the resin composition of the present invention, the blending ratio of the two components of vinyl chloride/ethylene copolymer and ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer is The amount of the ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer is preferably 20 to 200 parts by weight based on 100 parts by weight of the combined copolymer.

For the resin composition of the present invention, stabilizers such as calcium stearate, zinc stearate, calcium oxide, and magnesium oxide, antioxidants such as phenol and phosphite, dioctyl phthalate, diethyl Plasticizers such as hexyl adipate and dioctyl adipate; lubricants such as polyethylene-based, acid amide-based, and ester-based lubricants are added in amounts that do not substantially adversely affect the desired properties of the resin composition of the present invention. It can also be included, thereby improving the thermal stability, aging resistance, melt flowability during molding, mold adhesion prevention property, etc. of the resin composition.

(Example) Examples of the present invention will be described below along with comparative examples.

Example ethylene content is 4.0ffiit%, average degree of polymerization is 13
00 vinyl chloride/ethylene copolymer 100 parts by weight,
n-butyl acrylate content is 30% by weight, carbon monoxide content is 10%, melt index is 10dg/min,
Ethylene/carbon monoxide/(meth)acrylic acid alkyl ester copolymer with an N value of 1.3 (manufactured by DuPont) 100
! ! ffi part and epoxidized soybean oil (0-130P manufactured by Adeka Argus) 10! 1.0 parts by weight of a Ca-Zn stabilizer (Mark-37 manufactured by Adeka Argus) and 1.0 parts by weight of oxidized polyethylene wax (Highwax 4202E manufactured by Mitsui Petrochemicals) were added and kneaded. After kneading in a machine, the mixture was made into pellets by an extruder.

Furthermore, this pellet was extruded using an inflation mold to obtain a tube-shaped thin film with excellent transparency.Next, this thin film was used to make an infusion bag using a high-frequency sealing machine, and an eluate test was conducted. The item showed excellent results.

Comparative Example An ethylene/carbon monoxide/n-butyl acrylate copolymer had an n-butyl content of 30% by weight, a carbon monoxide content of 10% by weight, a melt index of 10 dg/min, and an N value of 1. 7 ethylene/carbon monoxide/acrylic acid n
A tubular thin film was obtained in the same manner as in Example 1 except that -butyl copolymer was used. The transparency of the obtained FIN was not desirable.

The physical properties of Examples and Comparative Examples on the ridges are shown in the table below.

In addition, total light transmittance is JISK6714, haze is JI
SK7105 and the eluate test were measured according to the Japanese Pharmacopoeia infusion plastic container test method.

(Blank below) (Effect) The resin composition of the present invention consists of a vinyl chloride/ethylene copolymer and an ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer. The resulting blood bags, blood tubes, etc. are excellent in terms of flexibility and transparency, and dioctyl phthalate does not elute and is absorbed and accumulated in the body through the blood, and acetic acid is desorbed and does not cause hemolysis or hemolysis. It had no adverse effect on cytotoxicity, and was also excellent in flexibility, heat resistance, and autoclave resistance.

The resin composition for medical equipment of the present invention can be suitably used for molding medical equipment such as medical catheters, tubes for blood transfusions and infusions, blood hangers, infusion bags, and tubes for blood circuits in artificial dialysis. For example, the resin composition of the present invention can be shaped into a film, a sheet, a plate, a container, a tube,
It can be formed into any shape, such as a cylinder, a rod, or a bag, depending on the type of intended medical device. For the molding, ordinary molding means such as extrusion molding, injection molding, casting molding, press molding, blow molding, etc. can be employed.

Claims (1)

[Scope of Claims] 1. A resin composition for medical equipment comprising a vinyl chloride/ethylene copolymer and an ethylene/carbon monoxide/(meth)acrylic acid alkyl ester terpolymer. 2. The ethylene content of the vinyl chloride/ethylene copolymer is
The resin composition for medical equipment according to claim 1, characterized in that the content is in the range of 1.0 to 8.0% by weight. 3. Melt index of ethylene/carbon monoxide/(meth)acrylic acid alkyl ester copolymer is 5dg/
3. The resin composition for medical equipment according to claim 1, wherein the resin composition has a structural viscosity index of 1.5 or more and a structural viscosity index of 1.5 or less.