JPH01270869A - Method of sterilizing polycarbonate resin molding - Google Patents

Abstract

PURPOSE:To prevent yellowing and to develop sufficient toughness and strength by sterilizing a polycarbonate resin into which polypropylene glycol is incorporated with the irradiation of ionizing radiation, then irradiating the resin with a specific quantity of UV rays. CONSTITUTION:The polycarbonate resin is the polymer or copolymer obtd. by a phosgene method which brings a dihydroxy diaryl compd. and phosgene into reaction or an ester exchange method which brings the dihydroxy diaryl compd. and carbonate such as diphenyl carbonate into reaction. The mol.wt. thereof is preferably 14000-35000 in terms of strength and the mol.wt. of the polypropylene glycol is in a 2000-6000 range. The content thereof is preferably 0.1-2.0wt.% by the weight of polycarbonate. The ionizing radiations contain alpha rays, gamma rays, and X-rays, etc., and particularly the gamma rays are more preferable. The ionizing radiation dose is about 2.5Mred and the irradiation quantity of the UV rays is preferably about 50-700Joule/cm<2>. The said rays are used at about 250-440nm wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for sterilizing polycarbonate resin moldings. Specifically, the present invention relates to a method for radiation sterilization of polycarbonate resin moldings used in various medical instruments and devices.

[Conventional technology]

Polycarbonate resin is tough and impact resistant.

It has excellent heat resistance, dimensional stability, gas barrier properties, and coexistence with blood, and is widely used as molded parts and film/sheet materials.

Used for container-like packaging devices for storing and packaging things such as artificial lungs, artificial kidneys, anesthesia absorption devices, intravenous connectors and accessories, medical devices such as blood centrifugation bowls, surgical tools, operating room tools, etc. It is being

When used in medical applications, these articles are usually fully sterilized.

Typical processing methods include heating in an autoclave, contact treatment with ethylene oxide, or irradiation with ionizing radiation such as gamma or electron beams.

[Problem that the invention seeks to solve]

However, each of these techniques has some drawbacks. In the case of autoclaves, many polymers, including polycarbonates and polyarylates, are thermally unstable.

This technique requires relatively high energy;
It is also often undesirable because the treated article retains moisture and must first be dried before use. The use of ethylene oxide is undesirable due to the toxicity, instability, and environmental concerns associated with disposal of this gas.

A useful alternative to these techniques is ionizing radiation sterilization because it can be carried out at low temperatures, is relatively inexpensive, and is essentially a dry process. However, irradiation of articles made from polycarbonate resins, polyarylates, or blends thereof with ionizing radiation commonly causes yellowing of the normally optically clear polymer.

For this reason, there are methods to offset the yellowing by mixing a blue colorant or the like into the polymer, as well as methods such as JP-A No. 1999/1996 and JP-A No. / x! J63/No., or JP-A-62-1.3
! A method of mixing an anti-yellowing agent as described in Publication No. 3''!6 has been proposed.

These methods either do not have a sufficient effect of preventing yellowing, or if they contain a sufficient amount of an anti-yellowing agent to be effective, they significantly impair the toughness and strength of the polycarbonate.

In addition, there have been problems such as appearance defects caused by volatilization of additives and the like during the manufacturing process of sheets, films, and molded products.

As described above, there has been a desire to develop a technology that prevents yellowing during sterilization with ionizing radiation and exhibits sufficient toughness and strength.

[Means for solving problems]

The inventors of the present invention have conducted intensive studies to develop a material that does not cause yellowing, which was insufficient with conventional techniques, has toughness and strength, and has satisfactory commercial value. However, in the present invention, a polycarbonate resin containing polypropylene glycol is irradiated with ionizing radiation and then sterilized with a certain amount of ultraviolet rays. By irradiating it, it is possible to achieve the objective effectively and in a short time. It has also been found that discoloration can be more effectively achieved by irradiating ionizing radiation in an oxygen atmosphere.

The present invention will be specifically explained below.

Polycarbonate resins are polymers or copolymers obtained by the phosgene method, in which various dihydroxydiaryl compounds are reacted with phosgene, or the transesterification method, in which dihydroxydiaryl compounds are reacted with carbonate esters such as diphenyl carbonate. Things are 2. Corbis (≠-hi)' o -Jt
-'/phenyl)propane (bisphenol A).

In addition to bisphenol A, the dihydroxydiaryl compounds include bis(≠-hydroxyphenyl)methane, /,/-bis(Hiro-hydroxyphenyl)ethane, 2
,2-bis(≠-hydroxyphenyl)butane, core 2
-bis(4cm hydroxyphenyl)octane, bis(
≠-hydroxyphenyl) phenylmethane, core 2-bis(ψ-hydroxy-3-methylphenyl)propane,
/,! -bis(4cm hydroxy-3-tert-butylphenyl)propane, core 2-bis(≠-hydroxy-3-
bis(hydroxyaryl)alkanes such as bromophenyl)propane, 2,2-bis(≠-hydroxy-3.t-dibromophenyl)furopane, 2,2-bis(≠-hydroxy-3.j-dichlorophenyl)propane, l
μ-his(Hiro-hydroxyaryl)cyclobentane,
/, bis(hydroxyaryl)cycloalkanes such as l-bis(≠-hydroxyphenyl)cyclohexane, Hiro,! '-dihydroxydiphenyl ether, ≠U
/-dihydroxy-3゜3/-dihydroxy diaryl ethers such as dimethyl diphenyl ether, gt
<t'-dihydroxydiphenyl sulfide, ≠, l'
- dihydroxydiaryl sulfides such as dihydroxy-3,3'-dimethyldiphenyl sulfide, <
dihydroxydiaryl sulfoxides, such as i, ta'-dihydroxydiphenyl sulfoxide, g, μ'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide,! +4”-dihydroxydiphenylsulfone,
Examples include dihydroxydiarylsulfoys such as ti,ti'-dihydroxy-3,3'-dimethyldiphenylsulfone.

These can be used alone or in a mixture of two or more,
In addition to these, piperazi/dibiperidyl, hydroquinone, resorcinol, ψ, ≠'-dihydroxydiphenyl, etc. may be used in combination.

The molecular weight of the polycarbonate is largely related to fluidity, but from the viewpoint of strength, a molecular weight of 1 aooθ to 36,000 is preferable.

The polypropylene glycol used in the present invention has a molecular weight in the range of 2,000 to 6,000, and the content thereof is preferably o, i to 2.0% by weight, more preferably o, z-t, o% by weight based on the polycarbonate. The polypropylene glycol can be blended into the polycarbonate resin by various means at any stage immediately before molding the final molded product.

The ionizing radiation doses used include alpha rays, deuteron rays,
They include proton beams, beta rays, electron beams, neutron beams, gamma rays, and X-rays, with gamma rays being particularly preferred commercially.

The ionizing radiation dose is usually 2. It is about J　M　rBd.

When irradiated with ionizing radiation, polycarbonate resin turns yellow. This is thought to be due to some chemical reaction occurring in the polycarbonate resin due to irradiation with ionizing radiation.

In the present invention, yellowing can be suppressed to some extent by adding polypropylene glycol, but the yellowing caused by this ionizing radiation can be further irradiated with ultraviolet rays, causing discoloration (not stopping yellowing, but causing yellowing). It fades discoloration and makes it transparent).

Although the details of the mechanism are not clear, it is thought that colored substances generated by ionizing radiation are decomposed or converted into other substances by ultraviolet rays.

If the amount of ultraviolet irradiation is too small, there will be little fading effect, and if it is too large, deterioration and coloring will occur due to ultraviolet rays, so it is preferably about 25 to 1000 joules/-! Q~
The irradiation amount is preferably about 700 joules/-. The wavelength of ultraviolet rays used is approximately 230 nm to ≠≠ nm.

Irradiation with ultraviolet rays may be performed at any time after irradiation with ionizing radiation.

Further, in the present invention, when the ionizing radiation irradiation is performed in an oxygen atmosphere, the color can be more effectively faded. The "oxygen atmosphere" is required to be about 70% or more oxygen.

In addition to polypropylene glycol, the present invention also includes various well-known additives, such as hydrolysis stabilizers such as epoxides, lubricants such as paraffin wax and silicone oil, antioxidants such as hindered phenols and phosphites, and triazine. Weather resistance imparting agents such as
It may also contain a phosphoric acid-based flame retardant.

〔Example〕

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

The measurement items in this example were carried out in the following manner.

(1) Appearance of molded product (test piece: ASTM D-Otsu 3j
Dumbbell piece) Visual observation (2) Yellowness (test piece: evening otmφx'/y 1
ncht plate) J-5K71O3 using a test piece with 3 thicknesses
I followed.

(3) Izod impact value: Tested according to ASTM D-coj6 using a test piece having a thickness of η inches.

(4) Tensile strength According to ASTM D-jjl.

Examples / - DA, Comparative Example / -4 Bisphenol A type polycarbonate with a molecular weight of 22,000 was blended with a predetermined amount of the additives shown in Table No. 210 using a coaxial bent extruder manufactured by Nakatani Kikai.
The mixture was kneaded and made into pellets at ℃. After drying this pellet with hot air, 3. Samples for physical property tests were made using a tφ2 injection molding machine (IS 73S manufactured by Toshiba Machinery Co., Ltd.) at a molding temperature of 300°C and a mold temperature of 10°C.

The yellowness of the molded product was determined by the Japan Isotope Association.
Sterilize by irradiating with tMrad gamma rays, and 2 days later use an ultraviolet irradiation device (Rapid Cure UVB-2o manufactured by Ushio Inc.)
ooR8/1ooG) was used to irradiate ultraviolet light. Table 1 shows the yellowness and appearance of the molded product after irradiation. The tensile strength and Izod impact value of the molded product were also measured, and the results are shown in Table-
It is also listed in .

For comparison, various physical properties were also measured for those that were not irradiated with ultraviolet rays and those that were not added with polypropylene glycol. The results are also listed in Table-7.

Examples, tr The molded products were irradiated with ultraviolet rays and the yellowness etc. were measured in the same manner as in Examples 1 to μ, except that the irradiation with ionizing radiation was carried out in an oxygen atmosphere. The results are shown in Table-7.

〔Effect of the invention〕

According to the method of the present invention, even if a polycarbonate molded product is sterilized with ionizing radiation, a molded product with good color tone can be obtained and is useful for various medical instruments, devices, and the like.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (4)

[Claims] (1) A method for sterilizing a polycarbonate resin molded article, which comprises irradiating the polypropylene glycol-containing polycarbonate resin molded article with ionizing radiation and then irradiating it with ultraviolet rays. (2) A method for sterilizing a polycarbonate resin molded article, which comprises irradiating the polypropylene glycol-containing polycarbonate resin molded article with ionizing radiation in an oxygen atmosphere and then irradiating it with ultraviolet rays. (3) The sterilization method according to claim 1 or 2, wherein the amount of polypropylene glycol added to the polycarbonate resin molded product is 0.1 to 2.0% by weight. (4) UV irradiation amount is 25 to 1000 joules/cm
The sterilization method according to claim 1 or 2, characterized in that ^2.