JPH06166807A - Polycarbonate resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. which hardly undergoes yellowing due to gamma-ray sterilization and is suitable for medical uses by compounding a polycarbonate resin with a specified amt. of an arom. compd. having an SR group. CONSTITUTION:This resin compsn. is obtd. by compounding 100 pts.wt. polycarbonate resin with 0.05-3.0 pts.wt. at least one arom. compd. having an SH group (e.g. benzylmercaptan). The compsn. hardly yellows even when irradiated with gamma-rays in a dose enough for sterilization. Since blood contained in a medical utensil made of the compsn. does not look dusky, a patient does not feel unpleasantly. The compsn. does not release a bad malador during its processing or use and is very useful for medical utensils and apparatuses.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polycarbonate resin composition used for medical applications. For more details,
TECHNICAL FIELD The present invention relates to a polycarbonate resin composition suitable for medical use, which shows little yellowing when sterilized by γ-ray irradiation.

[0002]

2. Description of the Related Art Polycarbonate resins are used in many industrial fields because they are excellent in transparency, hygiene, dimensional stability, impact resistance, etc., and one of them is used in medical tools and medical devices. ing. When used for medical purposes, it is usually sterilized before use. Conventionally, the sterilization treatment has been performed by treatment with ethylene oxide or steam treatment in an autoclave, but recently, sterilization by γ-ray irradiation, which can be performed at a low temperature at a relatively low cost, has been performed recently.

However, the polycarbonate resin has a drawback that it is yellowed by γ-ray irradiation, and this yellowing occurs regardless of the presence or absence of oxygen in the irradiation atmosphere. This yellowing not only deteriorates the appearance of the medical device or medical device, but when blood is passed through the yellowed device or device, for example, the blood appears to be blackened and causes discomfort to the patient. Therefore, it is necessary to improve yellowing due to γ-ray irradiation to an acceptable level.

Yellowing due to γ-ray irradiation also occurs in resins other than polycarbonate resin, and for example, γ of polyolefin resin
As a method of improving yellowing by irradiation with rays, blending benzhydrol, hydrocarbon oil, phthalate ester, hindered amine, pentaerythritol phosphite, etc. into polyolefin resin to reduce yellowing due to irradiation with γ rays, that is, γ ray resistance Is known to be given. However, even if these γ-ray improving agents are blended with a polycarbonate resin, γ-ray resistance cannot be imparted.

As a method for improving the γ-ray resistance of a polycarbonate resin, modern plastics January 1984, page 104, should be compounded with polyethylene terephthalate, and JP-A-61-215651 should be compounded with a boron compound. However, JP-A-62-135556 proposes blending a polyester polyol or an alkyl ether thereof. However, these methods have not yet been commercialized.

Further, JP-A 1-229052, JP-A 2-49058 and JP-A 2-115260.
The publication describes a method of blending an aliphatic thioalcohol or thioether compound to improve the γ-ray resistance of a polycarbonate resin. However, these thio compounds generate an offensive odor during use, deteriorate the environment at the time of molding, and are not sufficiently effective in improving the γ-ray resistance of the polycarbonate resin.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polycarbonate resin suitable for medical use, which shows little yellowing due to sterilization by γ-ray irradiation. The present inventor, as a result of extensive studies to achieve the above object, by adding a small amount of an aromatic compound having a mercapto group as a γ-ray resistance improver to a polycarbonate resin, the γ-ray resistance is significantly improved without a bad odor. That is, the present invention has been completed.

[0008]

According to the present invention, 100 parts by weight of a polycarbonate resin contains 0.05 to at least one compound selected from aromatic compounds having a mercapto group.
The present invention relates to a polycarbonate resin composition containing 3.0 parts by weight. The polycarbonate resin targeted by the present invention is produced by the reaction of a dihydric phenol and a carbonate precursor material. It is usually produced by an interfacial polycondensation method using phosgene or a transesterification reaction using a carbonic acid diester.

Examples of the dihydric phenol used here include hydroquinone, dioxydiphenyl and bis (4-
Hydroxyphenyl) methane, 1,2-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [hereinafter referred to as bisphenol A], 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) ) Sulfide, bis (4-hydroxyphenyl) sulfone, α, α′-bis (4-hydroxyphenyl) diisopropylbenzene and the like, and compounds in which the aromatic nucleus of these compounds is substituted with a lower alkyl group or a halogen, May be used alone or in combination of two or more. Of these, bisphenol A is particularly preferable.

In the interfacial polycondensation reaction using such dihydric phenol and phosgene, dihydric phenol is usually dissolved in an aqueous solution of an acid binder and phosgene is reacted in the presence of an organic solvent. As the acid binder, for example, a hydroxide of an alkali metal such as sodium hydroxide or potassium hydroxide is used,
As the organic solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. Reaction is usually 0
It completes at 40 ° C., preferably 20 to 30 ° C., in a few minutes to 5 hours. It is preferable to keep the pH of the reaction system at 10 or higher as the reaction progresses. Further, it is desirable to use an end terminating agent such as phenol or p-tert-butylphenol as a molecular weight modifier, and a catalyst may be used to accelerate the reaction. Examples of the catalyst include tertiary amines such as triethylamine, pyridine, tetra-n-butylammonium bromide, and tetra-n-butylphosphonium bromide, quaternary ammonium compounds, and quaternary phosphonium compounds. Further, an antioxidant can be added if necessary.

The transesterification reaction using a dihydric phenol and a carbonic acid diester is carried out by distilling the alcohol or phenol produced by stirring the dihydric phenol with the carbonic acid diester in an inert gas atmosphere while heating. The reaction temperature varies depending on the boiling point of the alcohol or phenol to be produced, but is usually in the range of 120 to 350 ° C. In the latter stage of the reaction, the system is depressurized to facilitate the distillation of the alcohol or phenol produced and complete the reaction.
Examples of the carbonic acid diester include diphenyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate and the like, among which diphenyl carbonate is preferable. A polymerization catalyst can also be used to accelerate the polymerization rate, and as the polymerization catalyst, hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide and potassium hydroxide, and alkalis of boron and aluminum hydroxides can be used. Metal salts, alkaline earth metal salts, quaternary ammonium compounds, alkoxides of alkali metals and alkaline earth metals, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, silicon compounds , Germanium compounds, organotin compounds, lead compounds, antimony compounds, manganese compounds, titanium compounds, zirconium compounds, etc., which are usually used for esterification and transesterification catalysts can be used. . The catalyst may be used alone or in combination of two or more kinds. The amount of these catalysts used is selected in the range of 0.0001 to 1% by weight, preferably 0.0005 to 0.5% by weight, based on the starting dihydric phenol.

The polycarbonate resin thus obtained may be a homopolymer or a copolymer,
It may be a mixture of these. Further, it may be a polycarbonate resin having a branched structure or a polyester carbonate resin containing an aromatic or aliphatic dicarboxylic acid having 8 or more carbon atoms as a copolymerization component. Its molecular weight is 17,000 to 40,000 in terms of viscosity average molecular weight.
Is suitable, and 20,000 to 30,000 is preferable.

The γ-ray improving agent used in the present invention is an aromatic compound having a mercapto group, such as benzyl mercaptan, thiosalicylic acid, thiosalicylic acid methyl ester, thiosalicylic acid ethyl ester, thiosalicylic acid phenyl ester, thiobenzoic acid, Examples thereof include thiocresol, thioxylenol, naphthalenethiol, triphenylmethanethiol and the like, and compounds having a substituent on the aromatic ring thereof, and these may be used alone or in combination of two or more. The amount of the γ ray resistance improver used is 0.05 to 3.0 parts by weight, preferably 0.1 to 2.0 parts by weight, based on 100 parts by weight of the polycarbonate resin. 0.05
If it is less than 10 parts by weight, it is difficult to obtain the desired effect of improving γ-ray resistance, and if it is more than 3.0 parts by weight, the heat resistance at the time of molding is deteriorated, resulting in poor appearance.

Any method may be appropriately adopted for blending the γ-ray resistance improver. For example, a simple method such as a method of pelletizing with an extruder after mixing with a tumbler or a Hengel mixer or a method of quantitatively charging with a feeder into a hopper of an extruder to pelletize is also sufficiently effective. The pellets are molded into medical devices, medical devices, parts, etc. by injection molding, extrusion molding, blow molding or the like. If necessary, the composition of the present invention may further contain, for example, a release agent, a stabilizer, an antioxidant, a coloring agent such as a dye or pigment, and the like.

[0015]

EXAMPLES The present invention will be further described below with reference to examples. In addition,
Parts in the examples are parts by weight.

[0016]

Examples 1 to 7 and Comparative Examples 1 to 3 100 parts of a polycarbonate resin having a viscosity average molecular weight of 22,000 obtained by an interfacial polycondensation reaction from bisphenol A and phosgene was dried at 140 ° C. for 6 hours, and then described in Table 1. The various γ-ray-improving agents were added and mixed in the amounts shown in the table, and the mixture was kneaded and extruded at 260 ° C. by an extruder to form pellets. The pellets were molded into a transparent plate of 45 × 50 × 2 mm at 280 ° C. by an injection molding machine. Cobalt 60 γ ray is 25 kg gray (k
Gy) Irradiation, the yellowness (YI) before and after irradiation is JIS K7103
And the degree of yellowing (ΔYI) was determined. The results are shown in Table 1.

[0017]

[Table 1]

[0018]

EFFECTS OF THE INVENTION The composition of the present invention has a low degree of yellowing even when irradiated with 25 kGy of γ-ray in an amount sufficient for sterilization. Since it does not look dark black, it does not cause discomfort to the patient, and it does not produce a bad odor during processing or use, and is extremely effective for medical devices and devices.

Claims (1)

[Claims] 1. A polycarbonate resin composition comprising 100 parts by weight of a polycarbonate resin and 0.05 to 3.0 parts by weight of at least one compound selected from aromatic compounds having a mercapto group.