JPH05186647A - Polypropylene-based resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, composed of a PP-based resin, a specific phenolic compound and a specified sorbitol-based compound in a specific proportion with hardly any yellowing and emission of malodor with radiation, capable of suppressing the deterioration in mechanical characteristics, excellent in stability and transparency and useful as medical equipment, etc. CONSTITUTION:The objective composition is composed of (A) 100 pts.wt. PP- based resin, (B) 0.01-1.0 pt.wt. phenolic compound expressed by formula I (R1 is 1-3C alkyl) and (C) 0.01-1.0 pt.wt. sorbitol-based compound expressed by formula II [R2 and R3 are H, 2-8C alkyl, alkoxy, hydroxyl group or halogen; m and n are 1-3; k is 0 or 1].

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polypropylene resin composition. More specifically, the present invention provides
A polypropylene-based resin composition that is excellent in stability against radiation, suppresses deterioration of mechanical properties such as tensile strength due to radiation irradiation, yellowing, generation of odor to an extremely low level, and is also excellent in transparency Is.

[0002]

2. Description of the Related Art Polypropylene resins are excellent in hygiene.
And because it has excellent mechanical properties such as rigidity and impact strength,
Widely used for food containers, medical instruments, etc. By the way, food containers, medical equipment, etc. have excellent transparency because it is necessary to confirm the true color tone of the internal harmful substances and whether dust or other foreign matter is mixed inside. Is required. Furthermore, food containers, medical instruments, etc. need to be sterilized before use, but in recent years, as an efficient sterilization method instead of conventional sterilization with water vapor, gas such as ethylene oxide or hydrogen peroxide. The sterilization method by irradiation is being widely used.

However, conventional polypropylene resins have relatively high stability to gases such as water vapor and ethylene oxide, and hydrogen peroxide, but extremely low stability to radiation. Therefore, polypropylene resins are exposed to radiation. When irradiated, there was a problem that mechanical properties such as tensile strength were deteriorated, yellowing and odor were generated. Furthermore, when a nucleating agent is added to improve the transparency of the polypropylene resin, there is a very inconvenient problem that the deterioration of mechanical properties due to irradiation of radiation becomes particularly remarkable.

[0004]

In view of the present situation, the problem to be solved by the present invention is that the stability to radiation is excellent, and therefore the mechanical properties such as tensile strength are deteriorated due to radiation irradiation, yellowing, and odor. It is an object of the present invention to provide a polypropylene-based resin composition in which the occurrence of is suppressed to an extremely low level and which is also excellent in transparency.

[0005]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, the present invention includes 100 parts by weight of a polypropylene resin, 0.01 to 1.0 parts by weight of a phenolic compound represented by the following general formula (A), and 0.01 parts of a sorbitol compound represented by the following general formula (B). To 1.0 part by weight of the polypropylene resin composition.

[0006]

(In the formula, R ₁ represents an alkyl group having 1 to 3 carbon atoms.)

[0008]

(In the formula, R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group having 2 to 8 carbon atoms, an alkoxy group, a hydroxyl group or a halogen atom, and m and n
Each independently represents an integer of 1 to 3, and k represents 0 or 1. )

The details will be described below. The polypropylene resin used in the present invention may be a propylene homopolymer, or a binary or terpolymer of propylene and an α-olefin such as ethylene, butene-1, hexene-1, 4-methylpentene. Or a mixture thereof.

The phenolic compound of the present invention is a phenolic compound represented by the general formula (A), and a preferred specific example thereof is that in which R ₁ in the general formula (A) is a methyl group or an isopropyl group. Can be given.

The amount of the phenolic compound of the present invention used is
0.01 to 100 parts by weight of polypropylene resin
It is 1.0 part by weight, preferably 0.03 to 0.3 part by weight. If the amount is too small, the stability to radiation is poor,
On the other hand, when the amount is too large, the effect obtained with respect to the increase in the amount used is saturated, which is uneconomical.

The sorbitol compound of the present invention is represented by the general formula (B), and specific examples thereof include
1,3,2.4-dibenzylidene sorbitol, 1 ・
3,2,4-di (p-ethylbenzylidene) sorbitol, 1,3,2,4-di (p-propylbenzylidene)
Sorbitol, 1,3,2,4-di (p-butylbenzylidene) sorbitol, 1,3,2,4-di (p-hexylbenzylidene) sorbitol, 1,3,2,4-di (p-ethoxybenzylidene) ) Sorbitol, 1.3-
Examples thereof include p-chlorobenzylidene-2,4-p-ethylbenzylidene sorbitol.

The amount of the sorbitol compound of the present invention used is 0.01 per 100 parts by weight of the polypropylene resin.
To 1.0 part by weight, preferably 0.05 to 0.7 part by weight. If the amount is too small, the effect of improving transparency is insufficient, while if the amount is too large, bleeding occurs.

In the polypropylene resin composition of the present invention, other additives such as a neutralizing agent, a light stabilizer, an ultraviolet absorber, an antistatic agent, a lubricant, a dispersant, a pigment and You may use together antioxidants other than the phenolic compound of this invention.

To obtain the polypropylene resin composition of the present invention, for example, the polypropylene resin, the phenol compound of the present invention and the sorbitol compound of the present invention are added in the respective specified amounts, and necessary additives are added, and a Henschel mixer is added. Mix well using a blender such as
The obtained mixture may be melted and pelletized by an extruder.

[0017]

The present invention will be described below with reference to examples. Example 1 has an intrinsic viscosity of 1.65 measured in tetralin at 135 ° C.
dl / g, 100 parts by weight of an ethylene-propylene random copolymer containing 3.5% by weight of ethylene, Sumitizer Chemical Co., Ltd. Sumilizer GA-80 (R _{1 of the} general formula (A)) as the phenolic compound of the present invention. Is a methyl group)
0.2 parts by weight, 1 as the sorbitol compound of the present invention
・ 3,2.4-Di (p-ethylbenzylidene) sorbitol 0.3 part by weight and calcium stearate 0.05
Parts by weight were mixed with a Henschel mixer and extruded into a pellet by using a 40 mmφ extruder in an atmosphere of 220 ° C. Injection pressure of the obtained pellets 60 kg / cm
A flat plate having a thickness of 2 mm was prepared under the injection molding conditions of ² G, molding temperature of 230 ° C., and mold temperature of 50 ° C.

The obtained flat plate was irradiated with γ-rays of a cobalt 60 radiation source at 50 KGy (5 Mrad), and then allowed to stand in air at 60 ° C. for 30 days, and the breaking strength and elongation at break in a tensile test before and after irradiation, and transparency. , Yellowing and odor were measured. In the tensile test, a test piece was prepared using JIS-K6758-2 type dumbbell, and the strength (kg / cm ² ) and elongation (%) at break at a tensile speed of 50 mm / min were measured. The transparency was measured with a direct-reading haze meter manufactured by Toyo Seiki Co., Ltd. (ASTM-D-1003). Yellowing is Yellow
nest Index (YI) to ASTM-D1925
It was measured according to. The odor was given to each stage by putting 10 g of the test piece in a 250 ml wide-mouthed reagent bottle and maintaining it in an oven at 60 ° C for 30 minutes, and then judging the odor level by the following 5 stages by 7 panelists. The average value of 7 people (the higher the value, the greater the odor) was evaluated. Odor judgment criteria Score judgment 0 Almost no odor 1 Slight odor 2 Clear odor 3 Strong odor 4 Strong odor The results are shown in Table 1.

Examples 2 to 3 and Comparative Examples 1 to 16 Example 1 was repeated except that the conditions shown in Tables 1 to 3 were used. The results are shown in Tables 1 to 3.

In Examples 1 to 3 according to the present invention, satisfactory results are shown for all evaluation items. On the other hand, Comparative Examples 1 to 16 that do not satisfy the requirements of the present invention are inferior in the following points. Comparative Examples 1 and 2 containing the phenolic compound of the present invention but not the sorbitol compound are inferior in transparency. Comparative Examples 3 to 5 containing the phenol compound of the present invention and the sorbitol compound not of the present invention are inferior in odor after irradiation. Comparative Example 6 containing the sorbitol compound of the present invention but not containing the phenol compound is inferior in the tensile test result after irradiation and the odor after irradiation. Comparative Examples 7 to 12 containing the sorbitol-based compound of the present invention and the phenol-based compound not according to the present invention have good transparency, but Comparative Examples 7, 8, 11 and 12 are inferior in yellowing (ΔYI). Cage,
Moreover, Comparative Examples 8, 11 and 12 are also inferior to the result of the tensile test after irradiation. Further, Comparative Examples 9 and 10 are inferior to the tensile test results after irradiation. Comparative Examples 13 to 15 containing a phenol compound not according to the present invention and a sorbitol compound not according to the present invention are inferior in yellowing (ΔYI), odor after irradiation, and tensile test result after irradiation. Comparative Example 16 containing only the phenolic compound not according to the present invention is inferior in transparency, yellowing (ΔYI) and tensile test result after irradiation.

[0021]

[Table 1] -------------------------------------------- Examples Comparative Example 1 2 3 1 2 3 4 Composition (parts by weight) * 1 Resin * 2 100 100 100 100 100 100 100 Phenol type antioxidant * 3 P1 P1 P1 P1 P1 P1 P1 amount 0.2 0.2 0.05 0.2 0.05 0.2 0.05 Sorbitol derivative type * 4 S1 S2 S2 --S3 S3 amount 0.3 0.3 0.2--0.3 0.2 Evaluation Transparency haze% 19 27 34 78 76 18 22 Yellowing YI Before irradiation -36 -38 -33 -28 -27 -36 -36 After irradiation -34 -35- 30 -26 -25 -32 -36 Δ YI 2 3 3 2 2 4 0 Tensile strength test Breaking strength kg / cm ² Before irradiation 350 350 350 350 350 350 350 After irradiation 240 240 190 240 220 240 190 Elongation at break% irradiation Before 570 570 570 570 570 570 570 After irradiation 520 510 60 540 120 510 60 Odor Before irradiation 1.3 0.6 0.7 0.3 0.5 2.5 2.4 After irradiation 1.8 1.0 1.3 1.0 1.7 4.0 4.0 −−−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−

[0022]

[Table 2] ------------------------------------------ Ratio Comparative Example 5 6 7 8 9 10 11 (Parts by weight) * 1 Resin * 2 100 100 100 100 100 100 100 Phenolic antioxidant type * 3 P1-P2 P3 P4 P4 P5 amount 0.05-0.2 0.2 0.1 0.2 0.2 Sorbitol derivative type * 4 S3 S1 S1 S1 S1 S1 S2 amount 0.1 0.3 0.3 0.3 0.3 0.3 0.3 Evaluation Transparency haze% 29 19 20 20 21 20 30 Yellowing YI Before irradiation -33 -38 -35 -34 -37 -38 -34 After irradiation -32 -37 -23 -18 -31 -30 -18 Δ YI 1 1 12 16 6 8 16 Tensile strength test Breaking strength kg / cm ² Before irradiation 350 340 350 350 350 350 350 After irradiation * 5 190 B 190 180 140 140 180 Elongation at break% Before irradiation 570 550 570 570 570 570 570 After irradiation * 5 60 B 120 60 20 20 60 Before odor irradiation 2.0 1.8 1.3 1.8 1.6 1.6 0.9 After irradiation 3.7 2.7 2.0 2.5 2.2 2.0 1.6 −−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−

[0023]

[Table 3] ------------------ Comparative example 12 13 14 15 16 Formulation (parts by weight) * 1 Resin * 2 100 100 100 100 100 Phenolic antioxidant type * 3 P5 P5 P5 P5 P5 amount 0.05 0.05 0.05 0.2 0.05 Sorbitol derivative type * 4 S2 S3 S3 S3-amount 0.2 0.1 0.2 0.3-Evaluation Transparency haze% 36 30 23 18 73 Yellowing YI Before irradiation -30 -31 -33 -33 -24 After irradiation -22 -23 -25 -18 -14 Δ YI 8 8 8 15 10 Tensile strength test Breaking strength kg / cm ² Before irradiation 350 350 350 350 350 After irradiation * 5 BBB 180 140 Elongation at break% Before irradiation 570 570 570 570 570 570 After irradiation * 5 BBB 60 20 Before odor irradiation 0.7 2.2 2.5 2.8 0.6 After irradiation 1.8 3.9 4.0 4.0 1.9 −−−−−−−−− −−−−−−−−−−−−−−−−−−−−

* 1 In addition to the composition shown in the table, 0.05 part by weight of calcium stearate was used as a common composition. Further, in Comparative Example 6, 0.1 parts by weight of bis (1,2,2,6,8-pentamethyl-4-peridyl) sebacate (Sanol LS770 manufactured by Sankyosha Co., Ltd.) was used in addition to those shown in the table. * 2 Ethylene-propylene random copolymer (ethylene 3.
5% by weight, intrinsic viscosity measured at 135 ° C. tetralin is 1.65 dl / g)

* 3 P1: Sumilizer GA-80 (manufactured by Sumitomo Chemical Co., Ltd., a phenolic compound in which R ₁ of the general formula (A) is a methyl group) P2: tetrakis (methylene-3- (3,5-di-te)
rt-butyl-4-hydroxyphenyl) propionate) methane (Ciba-Geigy Irganox 10
10) P3: 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (Irganox 3114 manufactured by Ciba Geigy) P4: Tris (2,4-di-tert) -Butylphenyl) phosphite (Irgafos 168 manufactured by Ciba-Geigy) P5: 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane (Topanol CA manufactured by ICI) , P1 are phenolic compounds according to the present invention, and P2 to P5 are phenolic compounds not according to the present invention.

* 4 S1: 1,3,2,4-di (p-ethylbenzylidene)
Sorbitol (NC-4 manufactured by Mitsui Toatsu Chemicals, Inc.) S2: 1,3,2.4-dibenzylidene sorbitol (EC-1 manufactured by EC Chemicals) S3: 1,3,2.4-di (p-methylbenzylidene) )
Sorbitol (Gelol MD manufactured by Shin Nippon Rika Co., Ltd.) In the above, S1 and S2 are sorbitol compounds according to the present invention, and S3 is a sorbitol compound not according to the present invention. * 5 B: Destroyed when punching dumbbells.

[0027]

As described above, according to the present invention, the stability to radiation is excellent, so that deterioration of mechanical properties such as tensile strength, yellowing, and generation of odor due to radiation irradiation are suppressed to an extremely low level. It was possible to provide a polypropylene resin composition having excellent transparency.

Claims (1)

[Claims] 1. 100 parts by weight of polypropylene resin, 0.01 phenol compound represented by the following general formula (A):
To 1.0 parts by weight and 0.01 to 1.0 parts by weight of a sorbitol compound represented by the following general formula (B). (In the formula, R ₁ represents an alkyl group having 1 to 3 carbon atoms.) (In the formula, R ₂ and R ₃ are each independently a hydrogen atom,
It represents an alkyl group, an alkoxy group, a hydroxyl group or a halogen atom having 2 to 8 carbon atoms, m and n each independently represent an integer of 1 to 3, and k represents 0 or 1. )