JPS6014778B2 - Method for manufacturing hydrophilic medical hard plastic moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a rigid,
The present invention relates to a surface treatment method for a hard plastic molded product in which only the surface of the strong plastic molded product is made hydrophilic in order to improve wettability with blood or prevent "fogging" caused by water vapor.

Conventionally, most of the plastics used for medical purposes are lipophilic and have poor wettability with water, blood, and the like. An exceptional hydrophilic plastic is polyvinyl alcohol aldehyde (called poval), which is of European quality. Polyvinyl chloride resin plasticized with a plasticizer is also hydrophilic, but it is also soft. Non-hydrophilic plastics are preferable in some medical applications, but they are also used in parts where wettability with blood is important, such as the disks of rotating disk oxygenators, capillaries, etc., and where internal permeation can occur due to cloudiness caused by water vapor condensation. Hydrophilic properties are required for applications where loss of the property is a concern, such as cases for various artificial organs and medical devices that keep blood warm and circulate. Harder materials are often desired.

There are many hydrophilic polymers, but most are water-soluble, and those made water-insoluble by crosslinking, such as polyhydroxyalkyl methacrylates, are normally hard but do not come into contact with water. As a result, it absorbs water, softens, and significantly reduces its strength. Copolymerization of hydrophilic monomers with monomers forming hydrophilic hard plastics, or blending of hydrophilic polymers with lipophilic hard plastics, etc., can also be considered; When a polymer having a hydrophilic group is introduced in an amount that exhibits sufficient hydrophilicity, it swells upon contact with water and its strength decreases, making it unusable for the above-mentioned purposes. As a result of searching for various plastics that can be used in these applications, the present inventors brought the surface of a hard plastic molded product containing alkanoyloxy groups into contact with sulfuric acid, and the alkanoyloxy groups present on the surface were exposed to sulfuric acid. It was discovered that hard plastic molded products exhibit hydrophilic properties by being esterified, and this led to the completion of the present invention.

That is, the present invention utilizes a reaction in which a high concentration of sulfuric acid is applied to a polymer containing an alkanoyloxy group, thereby transesterifying the alkanoyloxy group and sulfuric acid.

According to the method of the present invention, sulfate groups are introduced only onto the surface of the hard plastic molded article. Since the hydrophilicity of the sulfate group and its salt is extremely strong, practically sufficient hydrophilicity can be imparted by introducing an extremely small amount. Therefore, the fatty acid vinyl polymerization amount is 1% by weight or more, preferably 2% by weight or more. Further, if the amount of fatty acid vinyl polymerized is excessive, the softening point of the copolymer will be lowered and rigidity will be lost, so the amount is desirably about 2 weight percent or less. Furthermore, if the sulfuric acid is dilute, transesterification will not take place, and hydrolysis will occur to form vinyl alcohol, and hydroxyl groups will be produced on the surface of the plastic. Although hydrophilization is possible with this reaction, the hydrophilicity of the hydroxyl group is weak, and the above amount of vinylester is not sufficient. Therefore, the sulfuric acid concentration required for sulfation must be sufficiently high, at least 7% by weight or more, preferably 80% by weight or more.

However, it is easier to hydrolyze a fatty acid ester with sulfuric acid and then convert it into a sulfuric acid ester than to directly convert the fatty acid ester into a sulfuric acid ester. After hydrolysis with an alkali, it is preferable to perform sulfuric acid esterification with concentrated sulfuric acid.

Furthermore, the sulfuric acid referred to in the present invention includes fuming sulfuric acid, sulfuric anhydride, chlorosulfonic acid, and the like, and in some cases, chromic anhydride and the like can also be used together.

Further, these sulfuric acid esters added to the surface of plastics may be in an acid form, or may be in a form neutralized with an alkali and dissociated. Specific polymers that can be used to obtain the hard plastic molded product of the present invention include vinyl acetate/vinyl chloride copolymer, vinyl acetate/vinyl chloride copolymer,
Vinyl alkyl ether copolymer, pinyl propionate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer with vinyl chloride graft polymerized, ethylene/vinyl acetate copolymer with vinyl chloride and vinyl alkyl ether copolymer, Examples include graft polymerization of ester, vinyl acetate/methyl methacrylate copolymer, and vinyl propionate/methyl methacrylate copolymer.

Example 1 After molding a copolymer of 85% vinyl chloride and 15% by weight vinyl acetate into a plate shape, the oil and fat on the surface was washed with a detergent.
Two pieces were prepared after washing with water and drying.

One of the sheets was immersed in 50q080% sulfuric acid for 1 hour, washed with water, neutralized with a 5% aqueous solution of caustic soda, thoroughly washed with water, and then subjected to a wettability test. The wetness test involves dipping a test piece in distilled water and gently pulling it up to see how the water adheres to the surface. Immediately after being pulled up, water adhered to the entire surface of the treated specimen, and as time passed, the peel of the specimen gradually appeared from the top.

On the other hand, for the untreated specimen, only a small amount of water droplets remained immediately after being pulled up, and water did not adhere to most of the surface of the specimen. Example 2 A resin obtained by graft polymerizing 5 parts by weight of a copolymer of 55% by weight of ethylene and 45% by weight of pinyl acetate with 95 parts by weight of vinyl chloride was molded into a plate shape to prepare three test pieces.

Claims (1)

[Scope of Claims] 1. Hydrophilic medical use characterized by contacting the surface of a hard plastic molded article containing alkanoyloxy groups with sulfuric acid to convert the alkanoyloxy groups present on the surface into sulfuric acid esters. A method for manufacturing hard plastic moldings. 2 Hard plastic moldings contain 2 to 20 fatty acid vinyl
The manufacturing method according to claim 1, which is molded from a copolymer containing as a wt% copolymer component. 3. The manufacturing method according to claim 1 or 2, using sulfuric acid with a concentration of 80 wt% or more.