JPS5842638A - Polypropylene composition having improved radiation resistance - Google Patents

Abstract

PURPOSE:To provide the titled propylene compsn. which little suffers lowering in physical properties and discoloration due to irradiation, by blending a specified hindered amine compd. and a phenolic antioxidant. CONSTITUTION:0.05-0.3pt.wt. heterocyclic hindered amine compd. such as di- (2,2,6,6-tetramethyl-4-piperidyl) sebacate and 0.01-0.04pt.wt. phenolic antioxidant [1,3,5-tris(3-hydroxy-2,6-dimethyl-4-alkylbenzyl)isocyanurate wherein alkyl is a 2-12C branched alkyl such as tert-butyl]are blended with 100pts.wt. polypropylene such as a crystalline propylene (co)polymer. Since moldings prepd. from the resulting compsn. can be sterilized safely and effectively by ultraviolet light irradiation, the moldings are suitable for use as food packaging materials, medical instrument, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to polypropylene compositions with improved radiation resistance.

Conventionally, various stabilizers and additives have been added to polypropylene in order to maintain and improve its physical properties such as heat resistance and processing stability, depending on the purpose.

In addition, medical instruments such as syringes, bottle sets, clamps, food packaging bags, containers, films, and food wrapping materials have conventionally been sterilized by boiling or gas sterilization. Especially disposable pull medical equipment OdllF
i. Ethylene oxide has been treated with ethylene oxide, which until recently was generally considered safe.
Due to the suspicion, the allowable amount of residual ethylene oxide and by-products has been lowered, and a sterility test is required to replace and remove the residual gas and confirm subsequent sterilization.
The processing cost is relatively high compared to radiation sterilization processing. Therefore, sterilization methods ranging from ethylene oxide treatment to radiation (r-ray) irradiation are considered to be effective and are being used to treat OR bacteria in disposable medical instruments.

However, when polypropylene compositions are used, they are significantly decomposed and deteriorated by irradiation with 15 megarads, which is considered to be the standard for 0 sterilization doses, and mechanical toughness is reduced. There is a possibility of significant coloring (due to an increase in O-eluting components, or due to deterioration of various stabilizers, modifiers, and additives that are generally added for antioxidant and other purposes). Regarding the radiation treatment of polypropylene O medical devices, mainly syringes, the following proposals have been made: For example, mixing phenolic antioxidants and thiosynervates containing inocyanurate groups into t-propylene polymers ( Japanese Patent Publication No. 5
5-1i No. 57135), and a product in which a C-olefin O crystalline polymer has a hindered amine nitrogen atom (Japanese Patent Application Laid-open No. 55-1919?) are known.

However, regarding these prior art, the former is based on physical properties,
Improvements that maintain a balance between coloring, hygiene, toxicity, and O are not necessarily sufficient for those who aim to do so.As for the latter, although improvements have been made regarding coloring, the O processing process, physical properties, and heat resistance life are not necessarily sufficient; Until now, satisfactory quality and performance have not been obtained.

The present inventors conducted research on polypropylene with less discoloration and less loss of physical properties due to radiation and irradiation, and as a result, completed the present invention.

That is, in the present invention, a heterocyclic hindered amine compound 110 is added to 10.0 parts by weight of polypropylene.
5~αS parts by weight and t45-)lith(S-hydroxy-
2,4-dimethyl-4-alkyl-benzyl)in cyanurate (alkyl FiO,% C1,0 branched alkyl group) [101 to a04 parts by weight and t are blended t Characterized by radiation resistance O Improved nine polypropylene compositions.

The polypropylene used in the present invention is a crystalline polypropylene widely used as a material for molded articles, and a crystalline O copolymer mainly composed of propylene. -See,
Examples of the crystalline O copolymer mainly composed of prop-1-pyrene include ethylene-propylene random copolymer, ethylene-propylene plotter copolymer, propylene-1-butene copolymer, and the like.

Heteronitric hindered amine compound (hereinafter referred to as hindered amine compound) added in the present invention
i, a hindered amine nitrogen atom and optionally other heteroatoms. Preferably tit nitrogen 1fc consists of a 6-membered heterocycle containing oxygen. Gaege, di(2,2,6,6-tetramethyl-4-bihelicyl) sebacate, 4-benzoyloxy-z2. t6 tetramethyl biveridine, cono-phosphoric acid and N-(2- and droxyethyl)-2,2,46 tetramethyl-4-hydroxypiperidine and oait compound, t2. &4-tetra(2,2,&6tetrameter-4
-piperidyl)-butanetetracarboxylate, t4
-di(2,2,44-tetramethyl-4-piperidyl)-2,3-butanedione.

Tris-(2,2,44-tetramethyl-4-piperidyl) trimeresolt, L2.2. Melon 6-pe/tamethyl-4-piperidyl stearate), L2,2゜46-bentamethyl-4-piperidyl n-octoate, bis-(L
2.2.46-bentamethyl-4-piperidyl) sebacate, tris-(2°2.46-tetramethyl-4-piperidyl)-nitrile acetate, 4-hydroxy-2
, 2,44-tetramethylpyridine, 4-hydroxy-
Examples include tLz&6-pentamethylpiperidine.

And among these, di(2,2,46-tetramethyl-4-piperidyl)sebacate or succinic acid and irises-(2-human-xyethyl)-2,2,&6-titramethyl-4-hydroxypiperidine O condensate is particularly preferred.

L&5-)lith(S-hydroxy-) added in the present invention
2,6-dimethyl-4-alkyl-benzyl)in cyanurate is a hindered phenolic O-oxidation inhibitor in which the alkyl is an O8-(!1.0 branched alkyl group).

For example, % t&5-tris(5-hydroxy-L6-dimethelu-4-ingrobyrupendyl)in cyanurate.

1.45-Tris(S-hydroxy-2,6-dimethyl-4-tert-butyl-bendiA-)in cyanurate, L
! L5-) lis(5-hydroxy-λ6-cymethyl-4
-IK Nibutyl-benzyl) incyanurate, L&5
-) Lis(5-hydroxy-2,4-dimethyl-4-butylbenzyl)incyanurate, among which 111-tris(5-hydroxy-L6-dimethyl-4-tert-butyl -benzyl)in cyanurate is preferred.

The amount of O added to the stabilizer O polypropylene is preferably 11 to 12 parts by weight in the case of hindered amine compound O per 100 parts by weight of polypropylene. −
λ6-dimethyl-4-furkylbenzyl)in cyanurate (hereinafter referred to as phenolic antioxidant) is [10
1~(L04 parts by weight preferably i; ino 2~[Lo
5 parts by weight.

Further, the method of adding stabilizers such as these hindered amine compounds and phenolic antioxidants to polypropylene is carried out by a generally used stock addition method. For example, a suitable method is to mix a stabilizer with polypropylene, premix it, and then mix it in an extruder.

In addition to the above-mentioned O stabilizer, a neutralizing agent, a lubricant, a mold release agent, and a nucleating agent can be added to the O-polypropyref composition of the present invention.

The polypropylene composition of the present invention is suitable for applications such as medical instruments, food packaging materials, containers, etc., because the polypropylene composition of the present invention undergoes very little discoloration due to irradiation with radiation, causes little deterioration in physical properties, and does not impair safety and hygiene. be.

Hereinafter, the discoloration and physical property changes of polypropylene compositions due to radiation will be shown in Examples.

Note that S is parts by weight.

Example 1 Ethylene content 2-0% by weight, melt rate 70% (Mu8TM D-1238% 250°C, 2
To 100 parts by weight of an ethylene-propylene random copolymer of 140 f (hereinafter abbreviated as νR) & If710, O stabilizer, neutralizing agent (calcium stearate) (part by weight of Lt) and nucleating agent (LA2. 4-dipezylidene rubitol) a and 2 parts by weight, and pre-mixing was carried out using Henschel (Kisa).

Next, this O-temperature mixture was melt-kneaded using a 210'OO extruder to form pellets. Using these pellets, one 40 mm x 40 m x 1 mO test piece was molded using an injection molding machine. The specimen was irradiated with a cobalt-400 source for 10 hours at 55 megarads. rljiA before and after irradiation O
Hue was measured using a Colormeter UD-0111-2 (45-0) Digital #1 Color Difference Meter manufactured by Suga Test Instruments, in accordance with J Engineering 8 Z-81220 Illumination and Light Reception O Geometric Conditions 10 Method. Measured value (b value) 0 hue is: less than -50 is uncolored (O), -0 to less than -48 is very slightly yellow (0), and from -8 to less than -40 is slightly yellow (Δ) and -LO
The above was designated as yellow (X).

The acceptable standard for the hue of the r-ray irradiated edge was that the measured value was less than -4.8, very slightly yellow, and even 0. In addition, changes in physical properties were determined by oxidation of γ-ray irradiation 9 □ MiPH and monovalence of O heat resistance life at 135° C. open, and the results are shown in Table 1.

For comparison, test pieces were formed in the same manner for O (not using 0 combinations of the O stabilizer of the present invention) or for O exceeding the added amount, and changes in hue and physical properties O were measured and evaluated after irradiation with r-rays. The results are also listed in Table 1 above.

Stabilizer M; Di(2,2,4-tetramethyl-4-piperidyl)sebacate B; Kohatasen and 4-(2-hydroxyethyl)-4-hydroxy-2,2,46-tetramethylbiperidine condensation product with 0at45-tris(5-droxy-2,4-dimethyl-4-7i@tributyl-benzyl)in cyanurate D;
-hydroxyhydrocinnamate)] methane 2; octadecyl 5-di-tert-butyl-4-hydro-7 hydrocinnamate in Q: LtA-) lis(2-methyl-S-@tert-butyl-4
-Hydroxyphenol) butane G nitris(&5-di-tributyl-4-droxybenzyl)incyanurate i[:44'-butylidene-bis(5-methyl-6-
Tertiary butyl-phenol) t&5-) methyl -2,4
4-Tris (&5-di-tert-butyl-4 to droxybenzyl)benzene Example 2 100 parts by weight of polyglopylene homopolymer powder of 710 min. stabilizer and calcium stearate in the proportions shown in Table 2 105 parts by weight was blended, and a test piece was molded using the same method as in Example 1 to give 56 megarads.
Table 2 shows the results of evaluating changes in hue and physical properties after irradiation 17 in the same manner as in t.

For comparison, the same evaluation as in Tun was conducted without using the O stabilizer combination of the present invention, and the results are also listed in Table 2.

December 24, 1981 Haruki Shimada, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 139805, filed in 1982, Title of the invention: Polypropylene composition with improved radiation resistance, 3. Related: Patent applicant representative: Akira Matsuyama 4, Agent address: Toranomon-chome-24-11-6, Minato-ku, Tokyo Number of inventions to be increased by amendment None Z Subject of amendment (1) “Details of the invention” in the specification column (2) Contents of amendment to power of attorney a (1) From the last line of page 5 to the first line of page 6 of the specification,
-Hydroxy-2. 2, 6. 6-te(ramethylpyridine) to 4-hydroxy-2.2, 6.6-
Edited as ``Titramethylpiveridine''.

(2) On page 9, line 3, “6.5 megarads” is followed by “
Insert "so that the amount of radiation is the same."

(3) Supplement the power of attorney.

j List of attached documents (1) Power of attorney 1 copy (2)

Claims (1)

[Claims] Heterocyclic hindered amine compound (LO5~1s parts by weight and L&5-) lith(3-hydroxy-L4-dimethyl-) per 100 weight 11K of polypropylene
4-Furkyl-benzyl)ine cyanurate (however, alkyl is a branched alkyl group from Os to ass C) (
101 to 104 parts by weight of a radiation-resistant O-modifiable polypropylene composition.