JPH10168243A - Radiation-resistant polyolefin composition and molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can give a molded product made resistant to deterioration and coloration just after being irradiated and also made resistant to the advancement of deterioration after the lapse of a definite term by using a specified amount of a polymer selected among polyolefins, aromatic vinyl compound/aliphatic diene copolymers and functional-group- containing polyolefins as the principal component. SOLUTION: This composition mainly consists of 100 pts.wt. polyolefin (A) and 0.1-100 pts.wt. at least one polymer (B) selected among aromatic vinyl compound/aliphatic diene copolymers and functional-group-containing polyolefins. Component A is particularly desirably a propylene homopolymer or a propylene/2-12C olefin copolymer having a propylene content of 50wt.% or above. The functional-group-containing polyolefin is one containing 0.01-20wt.% carboxylic anhydride groups, carboxyl groups, hydroxyl groups, amido groups or alkoxysilyl groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyolefin composition, and more particularly to a polyolefin composition having excellent radiation resistance and a molded article having excellent radiation resistance formed from the composition.

[0002]

2. Description of the Related Art Polyolefins such as polypropylene
It is widely used in various molding fields because it has excellent mechanical properties, chemical resistance and the like, and is extremely useful in balance with economy. When a polypropylene molded product is used for a medical device or the like in each molding field, γ is used for sterilization.
In some cases, the molded product is irradiated with radiation such as a beam or an electron beam. At that time, in the case of a normal polypropylene molded product, the molded product itself is deteriorated by radiation, and the tensile elongation of the molded product is significantly reduced, causing problems such as becoming very brittle and yellowing. There was a problem above.

As a method for improving the radiation resistance of a polyolefin such as polypropylene, a method of adding a hindered amine compound or a phenol compound to a polyolefin (JP-A-55-19199, JP-A-58-4)
2638, JP-A-58-49737, etc.),
A method of mixing an ethylene / propylene-based elastic copolymer (EPM) or a method of further mixing an ethylene / vinyl acetate copolymer (both are disclosed in JP-A-56-127646). Method using propylene random copolymer (JP-A-60-5500)
No. 5), a method of mixing an ethylene-propylene random copolymer having a relatively high ethylene content (Japanese Patent Application Laid-Open No.
And the like.

[0004]

In the various compositions and methods proposed above, the improvement of the radiation resistance of polyolefins is not satisfactory although a certain degree of effect can be seen. However, it is difficult to solve the problem of coloring and the problem of progression of deterioration after a certain period of time after irradiation.

The present inventors have conducted intensive studies on radiation-resistant polyolefin compositions which solve the problems of the prior art. When the composition and a molded product obtained by molding the composition are irradiated with radiation, not only the problem of deterioration and coloring immediately after irradiation is solved, but also the problem of deterioration progressing after a certain period of time after irradiation. To find a solution,
The present invention has been reached.

As can be seen from the above description, it is an object of the present invention to suppress deterioration and coloring immediately after irradiation when irradiating radiation, and also suppress deterioration progress after a certain period of time after irradiation. And a radiation-resistant molded article obtained by molding the composition.

[0007]

[Means for Solving the Problems]

(1) (a) 100 parts by weight of a polyolefin (A), and 0.1 or more polymers 0.1 or more selected from the following group (b)
A radiation-resistant polyolefin composition containing 100 to 100 parts by weight as a main component. (B) -1: a hydrogenated copolymer (B-1) obtained by hydrogenating a copolymer comprising at least one aromatic vinyl compound polymer and at least one aliphatic diene polymer (b) -2: polyolefin containing a functional group (B-
2)

(2) Polyolefin (A) is a propylene homopolymer, and a propylene-olefin containing 50% by weight or more of propylene polymerized units obtained by copolymerizing propylene with an olefin other than propylene having 2 to 12 carbon atoms. The composition according to the above (1), which is one or more polyolefins selected from copolymers.

(3) The polyolefin (B-2) containing a functional group contains 0.01% by weight of one or more functional groups selected from a carboxylic anhydride group, a carboxyl group, a hydroxyl group, an amide group and an alkoxysilyl group. (1) which is a polyolefin having a functional group, the polyolefin having a content of 20% by weight to 20% by weight.
Or the composition according to (2).

(4) (a) Polyolefin (A) 100
A radiation-resistant molded article molded from a polyolefin composition containing 0.1 to 100 parts by weight of at least one polymer selected from the following group (b): (B) -1: a hydrogenated copolymer (B-1) obtained by hydrogenating a copolymer comprising at least one aromatic vinyl compound polymer and at least one aliphatic diene polymer (b) -2: polyolefin containing a functional group (B-
2)

(5) Polyolefin (A) is a propylene homopolymer, and a propylene-olefin containing 50% by weight or more of a propylene polymerized unit obtained by copolymerizing propylene with an olefin other than propylene having 2 to 12 carbon atoms. The radiation-resistant molded article according to the above (4), which is one or more polyolefins selected from copolymers.

(6) The polyolefin (B-2) having a functional group contains 0.01% by weight of one or more functional groups selected from a carboxylic anhydride group, a carboxyl group, a hydroxyl group, an amide group and an alkoxysilyl group. (4) which is a polyolefin having a functional group, the polyolefin having a content of from 20 to 20% by weight.
Or the radiation-resistant molded article according to (5).

Hereinafter, the configuration and effect of the present invention will be described in detail. Examples of the polyolefin as the component (a) constituting the polyolefin composition of the present invention include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. And olefins such as 1,3-methyl-1-pentene, among which olefin homopolymers or copolymers having 1 to 12 carbon atoms are used. Taking into account the moldability, heat resistance, economical efficiency and the like of the composition obtained among these, preferred are ethylene homopolymer, ethylene-olefin copolymer, propylene homopolymer and propylene-olefin copolymer. Particularly preferred are propylene homopolymers and propylene-olefin copolymers containing at least 50% by weight of propylene polymerized units obtained by copolymerizing propylene with olefins other than propylene having 2 to 12 carbon atoms. At least one polyolefin.

These polyolefins can be prepared by a conventionally known method, for example, a so-called Ziegler-based catalyst in which a titanium-containing solid catalyst component is combined with an organoaluminum compound, and in some cases, an electron donor is further combined as a third component of the catalyst, In recent years, a polyolefin obtained by (co) polymerizing an olefin using a so-called metallocene catalyst obtained by combining a metallocene compound containing a transition metal such as zirconium and a cocatalyst such as aluminoxane can be used. Polyolefins can also be used.

The component (b) constituting the polyolefin composition of the present invention is obtained by hydrogenating a copolymer comprising at least one aromatic vinyl compound polymer and at least one aliphatic diene polymer. Hydrogenated copolymer (B-1)
(Hereinafter, it may be abbreviated as hydrogenated copolymer (B-1).) Is an aromatic vinyl compound such as styrene, α-methylstyrene, p-methylstyrene, and pt-butylstyrene. Polymers, preferably polymers of styrene and α-methylstyrene, and butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4
An aliphatic diene polymer such as -dimethyl-1,3-hexadiene and 4,5-diethyl-1,3-octadiene, preferably a polymer of butadiene and isoprene;
A hydrogenated copolymer (B-1) in which the aliphatic diene portion of the copolymer having each unit is hydrogenated by 70% or more, preferably 80% or more.

As the structure of such a hydrogenated copolymer (B-1), when an aromatic vinyl compound polymer is represented by S and an aliphatic diene polymer is represented by D, the following structures can be used. is there. (SD) _m , wherein m is an integer of 1 to 5 and obtained by hydrogenation, for example, S-D
D, S-D-S-D-S, D-S-D-S-D-S-D, S-D
A copolymer obtained by hydrogenating a copolymer having a structure such as -S-D-S-D-S-D-S. A copolymer whose terminal is an aromatic vinyl compound polymer, for example, a copolymer obtained by hydrogenating a copolymer having a structure such as SDS, SDSDSDS or the like. Copolymer terminals having an aliphatic diene polymer, for example, those obtained by hydrogenating a copolymer having a structure such as DSD or DSDDSD. SD or DS above
Represents that they are truly chemically bonded or that they produced D continuously in the presence of S or produced S continuously in the presence of D. A mixture of S and D separately manufactured and mixed.

Further, the hydrogenated copolymer (B-
1) is an aromatic vinyl compound polymer in an amount of 3 to 90% by weight,
The content is preferably 5 to 80% by weight, particularly preferably 5 to 70% by weight.

As these hydrogenated copolymers (B-1), those obtained by a known method can be used, and not only one kind but also a mixture of two or more kinds can be used. Of course,
A commercially available hydrogenated copolymer (B) can also be used. Specifically, trade names DYNARON1320P, DYNARON1321P, DYNARON1910
P, DYNARON4400P, DYNARON4600P (all manufactured by Nippon Synthetic Rubber Co., Ltd.), SEPTON2043, SEPTON2063, SEPTON2007,
SEPTON1001, SEPTON2104, (Kuraray Co., Ltd.
Made), KRATON1650, KRATON1652, KRATON1657, KRATON17
01 (all manufactured by Shell Chemical Co., Ltd.) and the like.

Among the components (b) constituting the polyolefin composition of the present invention, the functional group-containing polyolefin (B-2) (hereinafter referred to as the functional group-containing polyolefin (B-
Sometimes it is abbreviated as 2). ) Represents at least one functional group selected from a carboxylic anhydride group, a carboxyl group, a hydroxyl group, an amide group, and an alkoxysilyl group by 0.0
It is a polyolefin having a functional group and containing 1% by weight to 20% by weight.

There are various methods for introducing the functional group into the polyolefin, and the method of graft-polymerizing a vinyl monomer having the functional group to the polyolefin is easy. That is, a state in which the polyolefin is dissolved in an organic solvent, in an aqueous suspension, or under gas phase reaction conditions, a radical initiator, and, if necessary, in the presence of a chain transfer agent, having the functional group. Add vinyl monomer and add 3
A method of graft polymerization under a temperature condition of 0 ° C. to 200 ° C., a method of supplying the above polyolefin, a radical initiator, and a vinyl monomer having a functional group described above to an extruder to perform graft polymerization. It can be obtained by a known method. The introduction of the functional group is not limited to one kind, and two or more kinds can be introduced.

The content of the functional group in the functional group-containing polyolefin (B-2) is adjusted to 0.1 from the viewpoint that the finally obtained composition of the present invention does not lose the radiation resistance and the inherent characteristics of the polyolefin. 01% to 20% by weight, preferably 0.05% to 20% by weight, particularly preferably 0.05% to
15 weight is desirable.

The polyolefin used in the production of the above-mentioned functional group-containing polyolefin (B-2) used in the present invention has been mentioned as the above-mentioned component (a) polyolefin constituting the polyolefin composition of the present invention. In addition to those similar to polyolefins, amorphous olefin copolymers such as ethylene-propylene rubber and the like can also be used.

As described above, for example, a vinyl monomer having a functional group is graft-polymerized to the above-mentioned polyolefin to obtain a functional group-containing polyolefin (B-2). As a vinyl monomer having such a functional group,
Graft polymerizable vinyl monomers having one or more functional groups such as carboxylic acid anhydride group, carboxyl group, glycidyl group, hydroxyl group, amide group, alkoxysilyl group and the like, specifically, maleic anhydride, Itaconic anhydride,
Vinyl monomers having a carboxylic acid anhydride group such as citraconic anhydride, allylsuccinic anhydride, glutaconic anhydride, nadic acid anhydride, methylnadic anhydride, tetrahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

Acrylic acid, methacrylic acid, crotonic acid,
Vinyl monomers having a carboxyl group such as maleic acid, fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, glutaconic acid, nadic acid, methylnadic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid.

Vinyl monomers having a glycidyl group such as glycidyl acrylate, glycidyl methacrylate, methyl glycidyl acrylate, methyl glycidyl methacrylate and allyl glycidyl ether.

Vinyl monomers having a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

Vinyl monomers having an amide group, such as acrylamide, N-methylacrylamide, and N-butoxymethylacrylamide.

Vinyltrimethoxysilane, vinyltriethoxysilane, vinyldimethylethoxysilane, vinyltriacetoxysilane, vinylmethyldiacetoxysilane, allyltrimethoxysilane, allyltriethoxysilane, γ-methacryloxytrimethoxysilane, γ-methacrylic Vinyl monomers having an alkoxy group such as roxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-acryloxypropylmethyldimethoxysilane. One or more monomers are used.

In addition to these vinyl monomers having a functional group, other monomers such as acrylic acid esters and methacrylic acid esters having a content of 40% by weight or less, preferably 30% by weight or less. Can be introduced into a polyolefin or the like by graft polymerization. These monomers that can be introduced may be used simultaneously with the graft polymerization of the monomer having a functional group to carry out graft polymerization, or the presence or absence of a radical initiator before or after the graft polymerization of the monomer having a functional group. Below, graft polymerization is also possible.

As the radical initiator used in the production of the functional group-containing polyolefin (B-2), known radical initiators can be mentioned, and organic peroxides are particularly preferred. Specifically, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, lauroyl peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxy) hexyne-3,2.5 -Dimethyl-2,5-di (t-butylperoxy) hexane and the like.

In the composition of the present invention, the polyolefin (A) as the component (a) and the hydrogenated copolymer (B) as the component (b) are used in an amount of 100 parts by weight of the polyolefin (A). And (b) 0.1 to 100 parts by weight, preferably 0.5 to 100 parts by weight of at least one polymer selected from a hydrogenated copolymer (B-1) and a functional group-containing polyolefin (B-2). 8
0 parts by weight, particularly preferably 1 to 50 parts by weight as a main component, together with the radiation resistance of the finally obtained composition and a molded article molded from the composition, the inherent chemical resistance of polyolefin, It is desirable from the viewpoints of oil resistance, moldability, and economy.

In producing the composition of the present invention, predetermined amounts of the above-mentioned polyolefin (A), hydrogenated copolymer (B-1) and functional group-containing polyolefin (B-2) are mixed,
Continue to knead well. As a mixing device, a high-speed stirring device such as a Henssel mixer (trade name) or a super mixer may be used, and as a kneading device, a Banbury mixer, a roll, a co-kneader, a single-screw or twin-screw extruder may be used. . The mixing conditions are not limited, but mixing is performed at room temperature to 100 ° C, preferably at room temperature to 60 ° C, for 1 minute to 1 hour, preferably 3 minutes to 30 minutes.
The kneading conditions are not limited, but the residence time in the extruder is 10 seconds to 30 minutes, preferably 20 seconds to 20 minutes.
Minutes. The kneading temperature is from 180 to 300C, preferably from 200 to 280C.

In the production of the above composition, an antioxidant, an ultraviolet absorber, an antistatic agent, a nucleating agent, a lubricant, a flame retardant, an antiblocking agent may be used within the scope of the object of the present invention. It is also possible to mix various additives such as a coloring agent, an inorganic or organic filler, and various synthetic resins.

The composition of the present invention thus obtained is molded by various known polyolefin molding methods, for example, techniques such as injection molding, extrusion molding, foam molding, and hollow molding. It can be used for various molded articles such as various containers, non-stretched films, uniaxially stretched films, biaxially stretched films, sheets, pipes, and fibers.

[0035]

Next, the present invention will be described specifically with reference to examples. Definitions of terms used in Examples and Comparative Examples and measurement methods are as follows.

MFR: Melt flow rate JIS K
7210 According to condition 4 of Table 1. (Unit: g / 10 minutes)

Yellowness (YI): Yellowness of a molded article measured according to JIS K7103. The higher the numerical value, the higher the degree of yellowness, which impairs the commercial value.

Elongation: Using a tensile tester manufactured by Toyo Seiki Co., Ltd., trade name: Strograph R-1 to pull a test piece at a tensile speed of 100
It is a breaking elongation measured by performing a tensile test under the condition of mm / min (unit:%). The lower the elongation, the more the deterioration has progressed compared to before the irradiation.

Example 1 (1) Production of Polyolefin Composition Hydrogenated styrene-based resin was mixed with 100 parts by weight of an ethylene-propylene copolymer powder having an MFR of 8.0 and an ethylene content of 2.5% by weight. DYNARON 132, a butadiene copolymer manufactured by Japan Synthetic Rubber Co., Ltd.
0P (styrene content 10% by weight, MFR 3.5)
Parts by weight, 2,6-di-t-butyl-p-cresol 0.
1 part by weight and 0.1 part by weight of calcium stearate are mixed, and the mixture is kneaded at 200 ° C. for 10 minutes using a Labo Plastomill manufactured by Toyo Seiki Co., Ltd., and then granulated to give a pellet-form present invention. Was obtained.

(2) Production of Molded Article The polyolefin composition obtained in the above (1) was molded into a sheet having a thickness of 0.5 mm at a press temperature of 200 ° C. using a press machine. ASTM D-1822-L from the sheet
A dumbbell test piece was prepared using a dumbbell cutter.

(3) Irradiation of radiation Using a Cockcroft-Walton electron accelerator, an acceleration voltage of 1 MV and a current value of 1 mA were applied to the area 20 c below the irradiation window.
Electron beam irradiation was performed at a point m through the conveyer so that the absorbed dose of the molded article obtained in the above (2) on the conveyer was 50 kGy.

(4) Evaluation of Physical Properties of Molded Article The YI and elongation of the molded article before and immediately after irradiation and of the molded article not irradiated with radiation were measured by the methods described above. One month after the irradiation, the elongation of the molded product was further measured. Table 1 shows various physical properties of the obtained molded article.

Example 2 The procedure of Example 1 (1) was repeated, except that a hydrogenated styrene-butadiene copolymer was used instead of ethylene-propylene rubber to graft copolymerize maleic anhydride.
A molded product was obtained in the same manner as in Example 1, except that a polyolefin composition was obtained using 5 parts by weight of a maleic anhydride group-containing ethylene-propylene rubber having a maleic anhydride content of 4.0% by weight. The radiation resistance was evaluated. Table 1 shows the evaluation results.

Comparative Example 1 A molded article was obtained in the same manner as in Example 1 except that the polyolefin composition was obtained without adding the hydrogenated styrene-butadiene copolymer in (1) of Example 1. Radiation was evaluated. Table 1 shows the evaluation results.

[0045]

[Table 1]

Example 3 (1) Production of Polyolefin Composition Pellets were prepared in the same manner as in Example 1 (1) except that the amount of the hydrogenated styrene-butadiene copolymer was changed to 10 parts by weight. A polyolefin composition of the present invention was obtained.

(2) Production of Molded Article A test piece was prepared from the polyolefin composition obtained in the above (1) in the same manner as in (2) of Example 1.

(3) Irradiation of radiation The absorbed dose of the molded article obtained in the above (2) is 50 gamma rays from Co-60 at a dose rate of 10 kGy / h.
Irradiation of gamma rays was performed so as to obtain kGy.

(4) Evaluation of Physical Properties of Molded Article The elongation of the molded article was measured before irradiation and two weeks after irradiation by the method described above, and the elongation of the non-irradiated molded article was measured for reference. Table 2 shows the elongation of the obtained molded product.

Comparative Example 2 In Example 1 (1), a styrene-butadiene copolymer was used instead of the hydrogenated styrene-butadiene copolymer, trade name JSR 1502 manufactured by Nippon Synthetic Rubber Co., Ltd.
(When a polyolefin composition was obtained by adding 10 parts by weight of a styrene content of 23.5% by weight, bubbles were generated during kneading with a Labo Plastomill, and the composition was formed into a sheet. Since no elongation was obtained, the elongation could not be measured, and the evaluation results are shown in Table 2.

Comparative Example 3 In Example 1, (1), JSR EP (trade name, manufactured by Nippon Synthetic Rubber Co., Ltd.), which is an ethylene-propylene rubber copolymer in place of the hydrogenated styrene-butadiene copolymer.
912P (propylene content 22% by weight, MFR8.
A molded article was obtained in the same manner as in Example 2 except that 10 parts by weight of 6) was added to obtain a polyolefin composition, and radiation resistance was evaluated. Table 2 shows the evaluation results.

[0052]

[Table 2]

[0053]

According to the polyolefin composition of the present invention and the molded product obtained by molding the composition, when irradiated with radiation, not only the deterioration and the coloring problem immediately after the irradiation do not occur, but also the radiation. No problem of deterioration progress after a lapse of a certain period of time. Therefore, use of the polyolefin in the molding field requiring radiation resistance, for example, the molding field requiring radiation sterilization, is greatly expanded.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ajat Strajat 1233 Watanukicho, Takasaki-shi, Gunma Japan Atomic Energy Research Institute Takasaki Research Institute (72) Inventor Don Bin 1233 Watanukicho, Takasaki-shi, Gunma Japan Atomic Energy Research Institute Takasaki Inside the research institute (72) Inventor Jun Saito 2-20-3 Momoshi, Kimitsu City, Chiba Prefecture (72) Inventor Shingo Kikukawa 2-17 Tatsumidai Higashi, Ichihara City, Chiba Prefecture

Claims (6)

[Claims] 1. A radiation-resistant polyolefin composition comprising, as main components, (a) 100 parts by weight of a polyolefin (A) and 0.1 to 100 parts by weight of at least one polymer selected from the following group (b): . (B) -1: a hydrogenated copolymer (B-1) obtained by hydrogenating a copolymer comprising at least one aromatic vinyl compound polymer and at least one aliphatic diene polymer (b) -2: polyolefin containing a functional group (B-
2) 2. A polyolefin (A) comprising a propylene homopolymer and a propylene-olefin containing at least 50% by weight of propylene polymerized units obtained by copolymerizing propylene with an olefin other than propylene having 2 to 12 carbon atoms. The composition according to claim 1, wherein the composition is one or more polyolefins selected from polymers. 3. A polyolefin containing a functional group (B-
2) contains 0.01% by weight to 20% by weight of one or more functional groups selected from a carboxylic anhydride group, a carboxyl group, a hydroxyl group, an amide group, and an alkoxysilyl group;
3. A polyolefin having a functional group.
A composition according to claim 1. 4. A polyolefin composition comprising (a) 100 parts by weight of a polyolefin (A) and 0.1 to 100 parts by weight of at least one polymer selected from the group (b) below. Radiation resistant molded products. (B) -1: a hydrogenated copolymer (B-1) obtained by hydrogenating a copolymer comprising at least one aromatic vinyl compound polymer and at least one aliphatic diene polymer (b) -2: polyolefin containing a functional group (B-
2) 5. The polyolefin (A) is a propylene homopolymer or a propylene-olefin copolymer containing 50% by weight or more of propylene polymerized units obtained by copolymerizing propylene with an olefin other than propylene having 2 to 12 carbon atoms. The radiation-resistant molded article according to claim 4, which is one or more polyolefins selected from polymers. 6. A polyolefin containing a functional group (B-
2) contains 0.01% by weight to 20% by weight of one or more functional groups selected from a carboxylic anhydride group, a carboxyl group, a hydroxyl group, an amide group, and an alkoxysilyl group;
6. A polyolefin having a functional group.
3. A radiation-resistant molded article according to claim 1.