JP2001294690A - Sterilization method of polycarbonate resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sterilization method in which a polycarbonate resin molded article has a very small yellowing and is hardly deteriorated in physical properties when subjected to ionizing radiation sterilization. SOLUTION: A method for sterilizing a polycarbonate resin molded article, which comprises irradiating a molded article made of a polycarbonate resin composition with ionizing radiation and then performing a heat treatment at a temperature of 30 to 130 ° C. in a deoxygenated atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for sterilizing a polycarbonate resin molded product. More specifically, the present invention relates to a treatment method after irradiating ionizing radiation to sterilize a polycarbonate resin molded product used for various medical instruments and devices and the like.

[0002]

2. Description of the Related Art Polycarbonate resin has mechanical strength,
It is widely used as a thermoplastic resin with excellent transparency, heat resistance and impact resistance. Due to such excellent properties, the resin is used as a member of various medical devices. Such medical device members include a syringe, a surgical tool, a container for containing and packaging a surgical instrument, an artificial dialyzer (artificial kidney case and cap), an artificial lung, an anesthesia inhaler, a venous connector, and the like. Accessories, blood centrifuge bowls, surgical tools, operating room tools, tubes for supplying oxygen to blood, tube connectors, heart probes and syringes,
Examples include surgical tools, operating room instruments, containers for storing intravenous injections, and the like.

[0003] In these medical applications, complete sterilization is usually performed. Examples of the sterilization treatment include an ethylene oxide gas contact treatment, a high-temperature and wet heat treatment using high-pressure steam in an autoclave, and a treatment of ionizing radiation such as γ-ray and electron beam. Among them, the ethylene oxide method is not preferred because it has problems of safety of the gas itself, toxicity (especially carcinogenicity, etc.), problems of residual gas in the medical device to be treated, and environmental problems related to disposal. The steam sterilization method has problems such as deformation of the material due to high temperature and humidity heat treatment, deterioration due to hydrolysis, and high processing cost, and further requires a drying step after the sterilization treatment. On the other hand, the ionizing radiation treatment method has the advantages that there is no problem of remaining in the product, the treatment can be performed in a dry state at a low temperature, the treatment cost is relatively low, and the like. Since it can be sterilized, it has been widely used.

However, when the polycarbonate resin is irradiated with such ionizing radiation, the polycarbonate resin changes its color to yellow with a chemical change. This discoloration significantly impairs commercial value, such as the inability to see the correct color tone of the contents in medical applications.

Various attempts have been made to prevent such yellowing. For example, there is known a method of adding a bluish colorant to a resin to cancel the yellow tint. However, in such a method, although the yellow tint can be eliminated by the amount of the coloring agent added, the color becomes darker as a whole, and the commercial value is also impaired.

A method of adding a polyether polyol or an alkyl ether thereof is also known (Japanese Patent Application Laid-Open No. 62-135556). Such a method provides some improvement but is still insufficient, and there is a problem that the addition of the compound easily causes decomposition of the polycarbonate resin and burns during molding.

Further, a method of adding an aromatic halogen compound has been disclosed (JP-A-2-129261). This method gives a rather good stabilizing effect on the polycarbonate resin, but it is a halogen compound,
There is the problem that environmental issues related to safety and disposal cannot be avoided.

[0008] JP-A-8-225732 discloses a method of adding an ether having a benzyloxy structure, such as benzyl ether or benzyl alcohol, or an alcohol compound. Although such a method provides some improvement, the effects of ionizing radiation irradiation during deoxygenation are still insufficient.

On the other hand, Japanese Patent Application Laid-Open No. 64-11551 proposes a method in which a polycarbonate resin molded article is irradiated with ionizing radiation and then irradiated with ultraviolet rays. Further, JP-A-2-13460 discloses a polycarbonate resin molded product containing polypropylene glycol,
A method of performing a heat treatment after irradiation with ionizing radiation has been proposed. These are methods in which yellowing caused by ionizing radiation is faded by ultraviolet irradiation or ordinary mere heat treatment (instead of stopping yellowing, the yellow discoloration is faded and made transparent). However, these methods cannot provide a sufficient effect.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of sterilizing a polycarbonate resin molded article with ionizing radiation sterilization, in which yellowing is extremely small and physical properties are hardly deteriorated. The present inventor has conducted intensive studies to achieve such an object, and as a result, after sterilizing a polycarbonate resin molded article by irradiation with ionizing radiation, by performing a heat treatment under a deoxygenated atmosphere, effectively and in a short time,
The present inventors have found that the polycarbonate resin which has once undergone yellow discoloration remarkably discolors, and has reached the present invention.

[0011]

That is, according to the present invention, a molded article made of a polycarbonate resin composition is irradiated with ionizing radiation, and then irradiated under a deoxygenated atmosphere for 30 to 30 minutes.
There is provided a method for sterilizing a polycarbonate resin molded article, wherein the method is heat-treated at a temperature of 130 ° C.

The polycarbonate resin used in the present invention includes various aromatic dihydroxy compounds or an interfacial polycondensation method in which a small amount of the polyhydroxy compound is reacted with phosgene, or a diphenyl carbonate or the like. It is a polymer or copolymer of an optionally branched thermoplastic aromatic polycarbonate synthesized by a melt polymerization method of reacting with a carbonate ester. A typical example is 2,2-bis (4
-Hydroxyphenyl) propane (bisphenol A)
And polycarbonate synthesized from the following.

The aromatic dihydroxy compound includes:
Bisphenol A, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2
-Bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4
-Hydroxy-3,5-dibromophenyl) propane,
2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,
5-dimethylphenyl) propane, 2,2-bis (3-
Phenyl-4-hydroxyphenyl) propane, 2,2
-Bis (3-cyclohexyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 9,9-bis (4-hydroxyphenyl) ) Fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-
Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3 , 3'-
Dimethyldiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-diphenyl sulfide, 4, 4'-dihydroxy-3,3'-
Diphenylsulfoxide, 4,4'-dihydroxy-
3,3'-diphenylsulfone, 1,3-bis {2-
(4-hydroxyphenyl) propyl @ benzene, 1,
4-bis {2- (4-hydroxyphenyl) propyl}
Benzene, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl and the like;
Is preferably used. These compounds can be used alone or in combination of two or more.

In order to obtain a branched aromatic polycarbonate resin, phloroglysin, 2,6-dimethyl-
2,4,6-tris (4-hydroxyphenyl) -3-
Heptene, 4,6-dimethyl-2,4,6-tris (4
-Hydroxyphenyl) -2-heptene, 1,3,5-
Tris (2-hydroxyphenyl) benzol, 1,
1,1-tris (4-hydroxyphenyl) ethane,
2,6-bis (2-hydroxy-5-methylbenzyl)
-4-methylphenol, α, α ′, α ″ -tris (4
-Hydroxyphenyl) -1,3,5-triisopropylbenzene, 3,3-bis (4-hydroxyphenyl)
Oxyindole (isatin bisphenol), 5-chloroisatin bisphenol, 5-bromoisatin bisphenol, 5,7-dichloroisatin bisphenol may be used.

The reaction by the interfacial polycondensation method is usually a reaction between dihydric phenol and phosgene, and is carried out in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used.
As the organic solvent, for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. Further, for promoting the reaction, for example, a catalyst such as a tertiary amine such as triethylamine, tetra-n-butylammonium bromide, or tetra-n-butylphosphonium bromide, a quaternary ammonium compound, or a quaternary phosphonium compound may be used. it can. At that time, the reaction temperature is usually 0 to 40 ° C., the reaction time is preferably about 10 minutes to 5 hours, and the pH during the reaction is preferably maintained at 9 or more.

In such a polymerization reaction, a terminal stopper is usually used. Monofunctional phenols can be used as such a terminal stopper. Monofunctional phenols are commonly used as molecular terminators for molecular weight control, and the resulting polycarbonate resins are capped by groups based on monofunctional phenols, so that Excellent heat stability. Specific examples of such monofunctional phenols include, for example, phenol, p-tert-butylphenol, p-cumylphenol and isooctylphenol. Further, as other monofunctional phenols, phenols or benzoic acid chlorides having a long-chain alkyl group or aliphatic polyester group as a substituent, or long-chain alkyl carboxylic acid chlorides can be used.

It is desirable that these terminal stoppers are introduced at least at 5 mol%, preferably at least 10 mol%, based on all terminals of the obtained polycarbonate resin. Or a mixture of two or more.

The reaction by the melt polymerization method is usually a transesterification reaction between a dihydric phenol and a carbonate ester. The dihydric phenol and the carbonate ester are mixed while heating in the presence of an inert gas to form an alcohol. Alternatively, it is carried out by a method of distilling phenol. The reaction temperature varies depending on the boiling point of the produced alcohol or phenol, but is usually in the range of 120 to 350 ° C. In the late stage of the reaction, the system was set to 1,300 Pa to 13 Pa (1
The pressure is reduced to about 0 to 0.1 Torr to facilitate the distillation of the produced alcohol or phenol. The reaction time is usually about 1 to 4 hours.

Examples of the carbonate ester include an optionally substituted ester such as an aryl group having 6 to 15 carbon atoms, an aralkyl group or an alkyl group having 1 to 4 carbon atoms. Specifically, diphenyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl)
Examples thereof include carbonate, dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. Among them, diphenyl carbonate is preferable.

A polymerization catalyst can be used to increase the polymerization rate. Examples of the polymerization catalyst include sodium hydroxide, potassium hydroxide, alkali metal compounds such as sodium and potassium salts of dihydric phenol, and water. Alkaline earth metal compounds such as calcium oxide, barium hydroxide and magnesium hydroxide; nitrogen-containing basic compounds such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylamine and triethylamine; alkoxides of alkali metals and alkaline earth metals Manganese, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, aluminum compounds, silicon compounds, germanium compounds, organic tin compounds, lead compounds, osmium compounds, antimony compounds Compounds, titanium compounds, usually the esterification reaction, such as zirconium compounds, there can be used a catalyst used in the transesterification reaction. The catalyst may be used alone or in combination of two or more. The amount of the polymerization catalyst used is preferably 1 × 10 ⁻⁹ to 1 × 1 with ^respect to 1 mol of the dihydric phenol as the raw material.
It is selected in the range of 0 ^-3 equivalents, more preferably 1 × 10 ^{-8 to} 5 × 10 ^-4 equivalents.

The polycarbonate resin has a viscosity average molecular weight (M) of preferably 10,000 to 100,000, more preferably 11,000 to 45,000, and
000 to 30,000 are particularly preferred. A polycarbonate resin having such a viscosity average molecular weight is preferable because sufficient strength is obtained, the melt fluidity during molding is good, and molding distortion does not occur. The viscosity average molecular weight of 0.7 g of polycarbonate resin in 100 ml of methylene chloride is 2
The specific viscosity (η _sp ) obtained from the solution dissolved at 0 ° C. was obtained by inserting it into the following equation. η _sp /c=[η]+0.45×[η] ² c (where [η]
Is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7

The polycarbonate resin used in the present invention preferably contains various ionizing radiation stabilizers, and the stabilizer has an effect of stabilizing against ionizing radiation and reduces coloring of the polycarbonate resin molded product. . Examples of such ionizing radiation stabilizers include polyalkylene glycols such as polypropylene glycol and tetrakis [methylene-3- (3 ′, 5′-di-).
Hindered phenols such as tert-butyl-4'-hydroxyphenyl) propionate methane, triazine compounds, thioether compounds described in JP-A-2-115260, and JP-A-6-166807. Compound having a mercapto group, disulfide, sulfoxide, sulfone, sulfonate,
Sulfur compounds such as sulfonamides, JP-A-8-225
For example, ethers having a benzyloxy structure, alcohol compounds, and sulfur compounds having a benzylthio structure such as benzyl sulfide described in JP-A-732-225, JP-A-8-225733, and JP-A-8-225734 can be used. Among these, at least one compound selected from a dibenzyl ether-based compound represented by the following formula (1) and a triazine-based compound represented by the following formula (2) is preferable. Further, the ionizing radiation stabilizer may be used alone or in combination of two or more kinds, and the effect may be synergistically exhibited.

The compounding amount of the ionizing radiation stabilizer is 0.01 to 10 parts by weight based on 100 parts by weight of the polycarbonate resin.
The range of parts by weight is preferable, the range of 0.1 to 5 parts by weight is more preferable, and the range of 0.1 to 3 parts by weight is further preferable. In the compounding amount in this range, the ionizing radiation stabilizing effect is sufficient, and the polycarbonate resin is hardly decomposed or burned during molding, without impairing the strength of the polycarbonate resin. It is also advantageous and advantageous in terms of cost.

[0024]

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(Wherein m and n are integers from 0 to 5; R ¹ and R ² may be the same or different; each represents a hydrocarbon group having 1 to 8 carbon atoms; A hydrocarbon oxy group, an acyl group having 1 to 8 carbon atoms, 1 to 8 carbon atoms
And at least one group selected from the group consisting of an acyloxy group and a polyoxyhydrocarbon group having 2 to 8 carbon atoms. )

[0026]

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Wherein R ³ is an alkylene group having 1 to 6 carbon atoms, R ⁴ is a phenyl group or a phenyl group substituted by 1 or 2 with a methyl group, and X is a hydroxyl group or —O—R ³ −
A Y-CH ₂ -R ⁴ group, Y is an oxygen atom or a sulfur atom. )

In the above-mentioned dibenzyl ether compound, m and n in the above formula (1) are integers of 0 to 5, preferably 0 to 2, and R ¹ and R ² are the same even if they are the same. It may be different, and may be a hydrocarbon group having 1 to 8 carbon atoms, a hydrocarbon oxy group having 1 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, an acyloxy group having 1 to 8 carbon atoms or 2 carbon atoms.
And at least one group selected from the group consisting of polyoxyhydrocarbon groups of 1 to 8.

The hydrocarbon group having 1 to 8 carbon atoms is an alkyl group, an aralkyl group or an aryl group having 1 to 8 carbon atoms, specifically, methyl, ethyl, butyl, iso.
-Butyl, tert-butyl, octyl, benzyl, phenyl and the like.

The hydrocarbon oxy group having 1 to 8 carbon atoms is an alkyloxy group, an aralkyloxy group or an aryloxy group having 1 to 8 carbon atoms, specifically, methoxy, butoxy, octyloxy, phenoxy, Benzyloxy and the like.

Specific examples of the acyl group having 1 to 8 carbon atoms include acetyl, propionyl, butyryl, benzoyl and the like.

Specific examples of the acyloxy group having 1 to 8 carbon atoms include acetoxy, propionyloxy, butyryloxy, benzoyloxy and the like.

Specific examples of the polyoxyhydrocarbon group having 2 to 8 carbon atoms include ethoxyethoxy and benzyloxyethoxy.

Specific examples of the dibenzyl ether compound represented by the above formula (1) include dibenzyl ether, bis (4-methylbenzyl) ether, bis (2-
Methylbenzyl) ether, bis (3-methylbenzyl) ether, 4-methylbenzylbenzylether,
Bis (2,4-dimethylbenzyl) ether, bis (2,5-dimethylbenzyl) ether, bis (2,6
-Dimethylbenzyl) ether, bis (3,5-dimethylbenzyl) ether, bis (4-iso-butylbenzyl) ether, 4-ethylbenzyl-4-butylbenzylether, bis (4-tert-butylbenzyl)
Ether, bis (4-octylbenzyl) ether, bis (4-phenylbenzyl) ether, bis (4-methoxybenzyl) ether, bis (4-butoxybenzyl) ether, bis (4-benzyloxybenzyl) ether, bis ( 4-acetylbenzyl) ether, bis {4- (ethoxyethoxy) benzyl} ether, bis {4- (benzyloxyethoxy) benzyl} ether, and the like, and dibenzyl ether, bis (4-methylbenzyl) ether, bis (4-benzyloxybenzyl) ether, bis {4- (benzyloxyethoxy) benzyl} ether and the like are preferable, and dibenzyl ether is more preferable.

In the triazine-based compound, R ³ in the above formula (2) has 1 to 6 carbon atoms, preferably 2 to 6 carbon atoms.
R ⁴ is a phenyl group or a phenyl group substituted by 1 to 2 with a methyl group, preferably a phenyl group, and X is a hydroxyl group or —O—R ³ —Y—CH ₂ —R ⁴
Y is an oxygen atom or a sulfur atom.

As the triazine compound represented by the above formula (2), specifically, 2,4,6-tris (benzyloxymethoxy) -1,3,5-triazine, 2,4,4
6-tris (2-benzyloxyethoxy) -1,3,
5-triazine, 2,4,6-tris {2- (4-methylbenzyloxy) ethoxy} -1,3,5-triazine, 2,4,6-tris {3- (2,6-dimethylbenzyloxy) ) Propyloxy} -1,3,5-triazine, 2,4,6-tris (2-benzyloxy-2-methylethoxy) -1,3,5-triazine, 2,4,6
-Tris (2-benzyloxy-1-methylethoxy)
-1,3,5-triazine, 2,4,6-tris (4-
Benzyloxybutoxy) -1,3,5-triazine,
2,4,6-tris (3-benzyloxy-1-methylpropyloxy) -1,3,5-triazine, 2,4
6-tris (benzyloxyneopentyloxy)-
1,3,5-triazine, 2,4,6-tris @ 2-
(3,5-dimethylbenzyloxy) hexyloxy}
-1,3,5-triazine, 2,4,6-tris (5-benzyloxy-1-methylpentoxy) -1,3,5-
Triazine,

2,4,6-tris (benzylthiomethoxy) -1,3,5-triazine, 2,4,6-tris (2-benzylthioethoxy) -1,3,5-triazine, 2,4 , 6-Tris {2- (4-methylbenzylthio) ethoxy} -1,3,5-triazine, 2,4,6
-Tris {3- (2,6-dimethylbenzylthio) propyloxy} -1,3,5-triazine, 2,4,6-
Tris (2-benzylthio-2-methylethoxy)-
1,3,5-triazine, 2,4,6-tris (4-benzylthiobutoxy) -1,3,5-triazine, 2,
4,6-tris (2-benzylthio-1-methylethoxy) -1,3,5-triazine, 2,4,6-tris (3-benzylthio-1-methylpropyloxy)-
1,3,5-triazine, 2,4,6-tris (benzylthioneopentyloxy) -1,3,5-triazine, 2,4,6-tris {2- (3,5-dimethylbenzylthio) Hexyloxy {-1,3,5-triazine, 2,4,6-tris (5-benzylthio-1-methylpentoxy) -1,3,5-triazine,

2,4-bis (benzyloxymethoxy)
-6-hydroxy-1,3,5-triazine, 2,4-
Bis (2-benzyloxyethoxy) -6-hydroxy-1,3,5-triazine, 2,4-bis {2- (4-
Methylbenzyloxy) ethoxy {-6-hydroxy-
1,3,5-triazine, 2,4-bis {3- (2,6
-Dimethylbenzyloxy) propyloxy} -6-hydroxy-1,3,5-triazine, 2,4-bis (2
-Benzyloxy-2-methylethoxy) -6-hydroxy-1,3,5-triazine, 2,4-bis (2-benzyloxy-1-methylethoxy) -6-hydroxy-1,3,5-triazine 2,4-bis (4-benzyloxybutoxy) -6-hydroxy-1,3,5-triazine, 2,4-bis (3-benzyloxy-1-methylpropyloxy) -6-hydroxy-1, 3,5-
Triazine, 2,4-bis (benzyloxyneopentyloxy) -6-hydroxy-1,3,5-triazine, 2,4-bis {2- (3,5-dimethylbenzyloxy) hexyloxy} -6 Hydroxy-1,3,5
-Triazine, 2,4-bis (5-benzyloxy-1
-Methylpentoxy) -6-hydroxy-1,3,5-
Triazine,

2,4-bis (benzylthiomethoxy)-
6-hydroxy-1,3,5-triazine, 2,4-bis (2-benzylthioethoxy) -6-hydroxy-
1,3,5-triazine, 2,4-bis {2- (4-methylbenzylthio) ethoxy} -6-hydroxy-1,
3,5-triazine, 2,4-bis {3- (2,6-dimethylbenzylthio) propyloxy} -6-hydroxy-1,3,5-triazine, 2,4-bis (2-benzylthio-2 -Methylethoxy) -6-hydroxy-
1,3,5-triazine, 2,4-bis (2-benzylthio-1-methylethoxy) -6-hydroxy-1,
3,5-triazine, 2,4-bis (4-benzylthiobutoxy) -6-hydroxy-1,3,5-triazine, 2,4-bis (3-benzylthio-1-methylpropyloxy) -6 Hydroxy-1,3,5-triazine, 2,4-bis (benzylthioneopentyloxy)
-6-hydroxy-1,3,5-triazine, 2,4-
Bis {2- (3,5-dimethylbenzylthio) hexyloxy} -6-hydroxy-1,3,5-triazine,
2,4-bis (5-benzylthio-1-methylpentoxy) -6-hydroxy-1,3,5-triazine and the like.

Among them, 2,4,6-tris (2-benzyloxyethoxy) -1,3,5-triazine,
4,6-tris {2- (4-methylbenzyloxy) ethoxy} -1,3,5-triazine, 2,4,6-tris (2-benzyloxy-1-methylethoxy) -1,
3,5-triazine, 2,4,6-tris (4-benzyloxybutoxy) -1,3,5-triazine,
4,6-tris (2-benzylthioethoxy) -1,
3,5-Triazine is preferred, and 2,4,6-tris (2-benzyloxyethoxy) -1,3,5-triazine, 2,4,6-tris (4-benzyloxybutoxy) -1,3,3. 5-Triazine and 2,4,6-tris (2-benzylthioethoxy) -1,3,5-triazine are more preferred.

The compound of the above formula (2) wherein X is a hydroxyl group has a tautomeric relationship with the compound represented by the following formula (3).

[0042]

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In the present invention, the compounding amount of at least one compound selected from the group consisting of the dibenzyl ether compound represented by the formula (1) and the triazine compound represented by the formula (2) is Bonnet resin 1
The range is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and more preferably 0.1 to 5 parts by weight with respect to 00 parts by weight.
A range of 1 to 3 parts by weight is more preferred. In the compounding amount in this range, the ionizing radiation stabilizing effect is sufficient, and the polycarbonate resin is hardly decomposed or burned during molding, without impairing the strength of the polycarbonate resin. It is also advantageous and advantageous in terms of cost.

As a method of blending the ionizing radiation stabilizer with the polycarbonate resin, it can be carried out by various means at any stage immediately before molding the final molded article.

The polycarbonate resin composition of the present invention comprises:
Any commonly used molding method such as injection molding, extrusion molding, blow molding, compression molding, transfer molding, etc. can be applied, and polycarbonate resin molded products such as thick molded products, sheets, films, tubes, etc. Molded into In particular, injection molding is preferably used, and polycarbonate is preferably used.
The type of the resin, the degree of polymerization, the type and amount of the ionizing radiation stabilizer, the amount and the type of the other additives are varied depending on the type and amount of other additives. .

Such polycarbonate resin molded products include:
The dose of ionizing radiation required for sterilization is applied. As the ionizing radiation used in the present invention, electron beam, γ-ray,
α-rays, neutron rays, X-rays and the like can be mentioned, and γ-rays or electron beams are particularly suitable for members of medical instruments. The dose of ionizing radiation is usually on the order of 25 kGy. Examples of such medical device members include an artificial dialyzer (artificial kidney case and cap), an artificial lung, an anesthesia inhaler, an intravenous connector and accessories, a blood centrifuge bowl, a surgical instrument,
Examples include operating room tools, tubes for supplying oxygen to blood, tube connecting devices, heart probes, and syringes, surgical tools, operating room instruments, containers for intravenous injections, and the like.

When irradiated with ionizing radiation, the polycarbonate resin molded product turns yellow. It is considered that this is because some chemical reaction has occurred in the polycarbonate resin molded article due to the irradiation of ionizing radiation.

The feature of the present invention resides in that the yellowing that has occurred in the polycarbonate resin molded article due to the ionizing radiation is faded by further heat treatment (the yellow discoloration is not stopped but the color is reduced to colorless). The heat treatment process is performed in a deoxidizing atmosphere. By performing the reaction in a deoxygenated atmosphere, the reaction between the chemical species generated in the polycarbonate resin by irradiation with ionizing radiation and oxygen in the air is suppressed, and the coloring of the polycarbonate resin due to the oxidation reaction is suppressed.

Further, the heat treatment in a deoxidized atmosphere according to the present invention is suitable for a polycarbonate resin molded article which has been yellowed by irradiation with ionizing radiation performed in a deoxygenated atmosphere, in particular, because its discoloration effect is exhibited.

The term "under a deoxidized atmosphere" in the present invention means a state in which oxygen is substantially removed. Specifically, the polycarbonate resin molded product is sealed with an oxygen-absorbing film or the like together with an oxygen absorbent, or the inside of a sealed container such as an oxygen-blocking film is replaced with an inert gas such as nitrogen, carbon dioxide, or argon. State.

In order to effectively discolor the yellowed polycarbonate resin molded product in a short time, the heat treatment is carried out at 30 to 1
It is carried out at a temperature of 30C, preferably 40-100C.
If the heat treatment temperature is lower than 30 ° C., the sufficient fading effect of the present invention cannot be obtained. If the heat treatment temperature exceeds 130 ° C., the molded product of the polycarbonate resin may be thermally deformed or impair the function of the medical module. The method of the heat treatment is not particularly limited, for example, a constant temperature constant temperature oven, a hot air dryer, a vacuum dryer, a microwave dryer, an infrared dryer, a far infrared heater, any method that is usually performed such as using a constant temperature water bath. Used. The heat treatment time is set according to the treatment temperature and the heating method, and although it cannot be unconditionally determined, it is usually from 5 minutes to 2 minutes.
Four hours is preferred. The heat treatment may be performed at any time after the irradiation with ionizing radiation.

The polycarbonate resin composition of the present invention contains various additives commonly used for polycarbonate resins, for example, higher fatty acids such as stearic acid and palmitic acid for improving the moldability. Glycerin, trimethylolpropane, esters or partial esters with alcohols such as pentaerythritol, release agents such as paraffin, heat stabilizers such as phosphate esters and phosphites, and antioxidants such as hindered phenols, Weather resistance improver, ultraviolet absorber, flame retardant, flame retardant auxiliary, impact resistance improver, antistatic agent, plasticizer, lubricant, compatibilizer, foaming agent,
Reinforcing agents, fillers, coloring agents such as dyes and pigments, and the like can be compounded within a range that does not adversely affect irradiation with ionizing radiation.

[0053]

The present invention will be described in more detail with reference to the following examples, but it should not be construed that the invention is limited thereto. The compounds used in this example are as follows.

Dibenzyl ether (in the above formula (1),
a compound in which m and n are 0) 2,4,6-tris (2-benzyloxyethoxy)
-1,3,5-triazine (in the above formula (2), R ³ is ethylene, R ⁴ is phenyl, and X is —O—R ³ —Y—CH ₂ —
Compounds in which R ⁴ and Y are oxygen atoms) 2,4,6-tris (2-benzylthioethoxy)-
1,3,5-triazine (in the formula (2), R ³ is ethylene, R ⁴ is phenyl, and X is —O—R ³ —Y—CH ₂ —
Compounds wherein R ⁴ and Y are sulfur atoms) 2,4,6-tris (2-benzyloxybutoxy)
-1,3,5-triazine (in the formula (2), R ³ is butylene, R ⁴ is phenyl, and X is —O—R ³ —Y—CH ₂ —
R ⁴ and Y are oxygen atoms) Polypropylene glycol, molecular weight: 2,000 The yellowness (YI) in this example was measured using a transparent test piece having a thickness of 2 mm according to JIS K7103.

[Examples 1 to 5, Comparative Examples 1 and 2] Compounds shown in Table 1 were added to 100 parts by weight of a bisphenol A-type polycarbonate resin (Panlite L-1225 manufactured by Teijin Chemicals Ltd.). Add the amount shown in Table 1 and add
mm uniaxial vent type extruder, barrel temperature 260-
Pellets were obtained by melt extrusion at 280 ° C. After drying the pellets at 120 ° C. for 5 hours or more in a hot air dryer, injection molding is performed at a cylinder temperature of 280 to 300 ° C.
A transparent test piece having a thickness of 2 mm was prepared. An oxygen absorbent (manufactured by Mitsubishi Gas Chemical Co., Ageless) was added to the EVA /
Polyethylene / nylon bags (Terraoka Co., Ltd.
Nylon lami standard bag) was irradiated with 25 kilogray (kGy) of cobalt 60γ ray. The yellowness after irradiation (YI) was 14.8, 2,4,6-tris (2-benzyloxyethoxy) -1,3,5-triazine, 18.2, 2,4,4, respectively. 6-tris (2-benzylthioethoxy) -1,3,5-triazine: 26.0;
2,4,6-tris (2-benzyloxybutoxy)-
1,3,5-triazine: 15.9. Next, the test piece was left standing at 20 ° C. or heat-treated at a temperature and time shown in Table 1 using a constant temperature incubator, while being sealed in a bag together with the oxygen absorbent. The results are shown in Table 1.

[Comparative Examples 3 to 5] Cobalt 60γ ray, 25
The yellowness (YI) after irradiation was measured in the same manner as in Example 1, except that kilogray (kGy) was irradiated in air.
YI after irradiation is dibenzyl ether: 7.2, 2,4,6-tris (2
-Benzyloxyethoxy) -1,3,5-triazine: 10.2 polypropylene glycol: 10.0. Next, the test piece was heat-treated in air using a constant temperature incubator at the temperature and time conditions shown in Table 1.
The results are shown in Table 1.

[0057]

[Table 1]

[0058]

The method for sterilizing a polycarbonate resin molded article of the present invention is an excellent method for fading the yellowing of the polycarbonate resin molded article due to ionizing radiation irradiated for sterilization, and the polycarbonate resin having a good color tone. A molded product is obtained. Therefore, it is extremely useful as a method for sterilizing medical products and members of medical devices to be subjected to ionizing radiation treatment.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 69/00 C08L 69/00 (72) Inventor Fumitaka Kondo 1-2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Teijin Chemicals F-term (reference) 4F073 AA09 AA15 AA31 BA26 BA43 BA44 CA42 CA61 CA63 CA64 CA65 EA71 EA72 GA01 HA04 HA05 4J002 CG001 ED056 EU186 FD036 GB01

Claims (5)

[Claims] 1. A method for sterilizing a polycarbonate resin molded article, comprising irradiating a molded article made of a polycarbonate resin composition with ionizing radiation, and then performing a heat treatment at a temperature of 30 to 130 ° C. in a deoxygenated atmosphere. . 2. The method according to claim 1, wherein the polycarbonate resin composition comprises a polycarbonate resin and an ionizing radiation stabilizer. 3. The anti-ionizing radiation stabilizer is at least one compound selected from a dibenzyl ether compound represented by the following formula (1) and a triazine compound represented by the following formula (2). A method for sterilizing a polycarbonate resin molded product according to the above. Embedded image (In the formula, m and n are integers of 0 to 5, R ¹ and R ² may be the same or different, and each may be a hydrocarbon group having 1 to 8 carbon atoms, a hydrocarbon group having 1 to 8 carbon atoms. And at least one group selected from the group consisting of an oxy group, an acyl group having 1 to 8 carbon atoms, an acyloxy group having 1 to 8 carbon atoms, and a polyoxyhydrocarbon group having 2 to 8 carbon atoms.) (Wherein, R ³ is an alkylene group having 1 to 6 carbon atoms, R ⁴
Is a phenyl group or a phenyl group substituted by 1 to 2 with a methyl group, and X is a hydroxyl group or -OR ³ -Y-CH ₂ -R ⁴
Y is an oxygen atom or a sulfur atom. ) 4. The polycarbonate resin molded article according to claim 2, wherein the polycarbonate resin composition is a polycarbonate resin composition comprising 100 parts by weight of a polycarbonate resin and 0.01 to 10 parts by weight of an ionizing radiation stabilizer. Sterilization method. 5. The method according to claim 1, wherein the irradiation with ionizing radiation is performed in a deoxygenated atmosphere.