JP3147138B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition, and more particularly to a novel polyolefin resin composition having excellent flexibility and mechanical strength at room temperature.

[0002]

2. Description of the Related Art Conventionally, as a soft resin used for a sheet or a film, a soft vinyl chloride resin containing a plasticizer has been frequently used. This soft vinyl chloride resin is very flexible at room temperature with an elastic modulus of 100 kg / cm ² or less, and has excellent tensile strength against tensile or compressive stress of 50 to 200 kg / cm ² and excellent mechanical properties. There is. Further, even when deformed by an external force at room temperature, the strain is almost recovered when the external force is released, and the stress relaxation property is excellent. However, this soft vinyl chloride resin has social problems such as toxicity problems due to bleed-out of plasticizers and vinyl chloride monomers, and acid rain problems due to generation of hydrogen chloride gas during incineration.

On the other hand, soft resins comparable to the above soft vinyl chloride resins include ethylene / vinyl acetate copolymers,
There are ethylene-ethyl acrylate copolymers, ionomer resins, linear low-density polyethylenes, ultra-low-density polyethylenes, ethylene-propylene copolymers and other ethylene-based copolymers. However, most of these soft resins have an elastic modulus at room temperature of 600 to 2,000 kg / cm.
² is less flexible than the above soft vinyl chloride resin, and those having high flexibility have a tensile strength of about 20 kg /
cm ² or less, low mechanical strength and lacks practicality. Also,
A sheet or film made of these soft resins undergoes a stress relaxation test at room temperature (a strain smaller than the yield point strain is applied, and the state of holding the stress is observed while maintaining a certain amount of deformation). Decreases,
Eventually, deformation remains even after the stress is released, and the elastic recovery force is inferior.

Further, as an attempt to soften a polypropylene resin having excellent mechanical properties, propylene and ethylene are randomly copolymerized to lower the melting point and to impart flexibility while maintaining sufficient mechanical strength. That is being done. However, with the current technology, the ethylene content can only be increased to at most 5 to 6% by weight, and none having the flexibility and elastic recovery power comparable to the above-mentioned soft vinyl chloride resin has yet been obtained.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have developed a resin which is free from the drawbacks associated with the environmental and social problems of soft vinyl chloride resin and which has excellent flexibility and elastic recovery. The present inventors have conducted intensive studies with the aim of providing a composition and completed the present invention. The present invention comprises (a) 2 to 50% by weight of an amorphous polyolefin obtained by copolymerizing propylene with ethylene and / or butene-1, and (b) 50 to 98% by weight of a polyolefin resin mainly composed of ethylene. , Tensile modulus at room temperature is 50 ~
1,500 kg / cm ² , strength 20-150 kg / c
m ² , the elastic recovery is in the range of 40 to 75%, and the amorphous polyolefin obtained by copolymerizing propylene with ethylene and / or butene-1 has an ethylene content of 1 to 20.
Propylene, butene-1 content is 1 to 7% by weight
0% by weight with the balance being propylene and ethylene content of 1
A resin composition characterized by having a butene-1 content of 1 to 70% by weight, and the balance being propylene. The resin composition of the present invention is a wrap film for business or household use, a sheet or film for packaging of fibers and miscellaneous goods, a sheet for building materials in the civil engineering and construction fields or a base material for fibers, tapes, metal surface protection films, pipes, It can be suitably used for various applications such as hoses and laminated materials.

Hereinafter, the present invention will be described in detail. The amorphous polyolefin of the component (a) of the present invention is mainly composed of propylene and / or butene-1 obtained by copolymerizing propylene with ethylene and / or butene-1 such that each monomer unit is randomly arranged. Is a copolymer having an ethylene content in the range of 1 to 20% by weight,
And / or the butene-1 content ranges from 1 to 70% by weight, preferably from 10 to 70% by weight, with the balance being propylene. Further, the number average molecular weight of the copolymer is 1,000.
~ 20,000, preferably 2,000 ~ 10,000
Range. When the ethylene content of the amorphous polyolefin is 20% by weight or more, the mechanical strength of the obtained resin composition is inferior, the surface tackiness is increased, and handling becomes difficult. When the butene-1 content is 70% by weight or more, the resulting resin composition has a low softening point,
Heat resistance around 0 ° C is poor. Number average molecular weight is 1,000
When it is less than the above, the cohesive strength is inferior and the mechanical strength of the resin composition becomes insufficient. Also, this amorphous polyolefin is
The crystallinity by the DSC method is less than 20%, the softening point by the ring and ball method is 90 to 170 ° C, and the melt viscosity at 190 ° C is in the range of 200 to 20,000 cps.
Further, regarding the mechanical properties of this amorphous polyolefin alone at room temperature, the breaking point strength was 1 to 50 kg /
cm ² , the elongation at break is 20-1200%,
The tensile modulus is in the range of 10 to 500 kg / cm ² .

The polyolefin resin mainly composed of ethylene as the component (b) of the present invention is selected from ethylene homopolymer, ethylene and butene-1, hexene-1,4-methylpentene-1 and octene-1. Α-olefin 1
Examples thereof include an ethylene-α-olefin copolymer obtained by copolymerizing ％ 40% by weight or an ethylene-vinyl acetate copolymer obtained by copolymerizing ethylene and vinyl acetate by 1-30% by weight. These polyolefin resins are extruded,
Examples include those generally commercially available for injection molding, blow molding and the like.

The resin composition of the present invention is obtained by blending the above component (a) in a ratio of 2 to 50% by weight and component (b) in a ratio of 50 to 98% by weight. (A)
If the content of the component is less than 2% by weight, flexibility at room temperature is lacking, and sufficient elastic recovery cannot be obtained. Also, 50
If the content is more than 10% by weight, the mechanical strength becomes too low and cannot be put to practical use.

The resin composition of the present invention containing an amorphous polyolefin resin obtained by copolymerizing propylene with ethylene and / or butene-1 has a tensile modulus at room temperature of 50 to 1,500 kg / cm ² , Strength is 20-15
0 kg / cm ² , the elastic recovery is in the range of 40 to 75%, and it has almost the same performance as soft vinyl chloride resin. There is no particular limitation on the method of blending the components (a) and (b),
It can be carried out by a method commonly used in the production of a conventional polyolefin composition, for example, heat-melt kneading using a kneader such as a kneader or a Banbury mixer or a single-screw or twin-screw extruder. If necessary, additives such as a heat stabilizer, an antioxidant, a lubricant, and a nucleating agent, or a reinforcing material such as calcium carbonate, mica, talc, and short glass fiber, or a filler can be added.
Further, other thermoplastic resins, thermoplastic elastomers and the like can be blended.

[0010]

EFFECT OF THE INVENTION The resin composition of the present invention has no disadvantages related to the environmental and social problems of the soft vinyl chloride resin,
In addition, it has flexibility, elastic recovery, and non-adhesiveness comparable to soft vinyl chloride resin, and is used for commercial and household wrap films, packaging sheets and films for textiles and miscellaneous goods, and for building materials in the civil engineering and construction fields. It can be suitably used for various uses such as a sheet or a base material for a fiber, a tape, a metal surface protective film, and the like.

In the present invention, the flexibility, mechanical strength and elastic recovery at room temperature were measured by the following methods. 180
The resin composition obtained by melting and kneading the components (a) and (b) at a predetermined mixing ratio for 30 minutes using a Brabender small kneader set to a temperature of 180 ° C. and a pressing pressure of 1 ° C.
A sheet having a thickness of 2 mm is formed by hot pressing at 00 kg / cm ² . (Flexibility, mechanical strength) The obtained sheet was punched out with a JIS No. 2 dumbbell to obtain a test specimen for a tensile test. This is J
According to IS K7113 “Plastic tensile test method”, the distance between chucks is 80 mm, and the crosshead speed is 5
A tensile test at 23 ° C. was performed at 0 mm / min to determine a tensile modulus (kg / cm ² ) as a measure of flexibility and a tensile strength (kg / cm ² ) as a representative value of mechanical strength. (Elastic recovery rate) Initial stress when the specimen was stretched to 20% strain at a crosshead speed of 500 mm / min and a test temperature of 23 ° C. and held at the same strain by the same test method as above using the test piece. : Σ ₀ and stress: σ after 1 minute (σ / σ ₀ × 100:%) to evaluate stress relaxation.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

(Resin used in the test) Amorphous polyolefin of component (a)

[0014]

[Table 1]

(B) Polyolefin resin containing ethylene as the main component (manufactured by Ube Industries, Ltd.)

[0016]

[Table 2]

EXAMPLES AND COMPARATIVE EXAMPLES A resin composition in which an amorphous polyolefin of component (a) and a polyolefin resin mainly composed of ethylene of component (b) were blended in a predetermined ratio, the tensile modulus at 23 ° C. The strength and stress relaxation were measured. Table 3 shows the results
Shown in

[0018]

[Table 3]

Claims (4)

(57) [Claims] 1. An amorphous polyolefin obtained by copolymerizing (a) propylene with ethylene and / or butene-1.
50% by weight and 50% to 98% by weight of a polyolefin resin mainly composed of ethylene (b) having a tensile modulus of elasticity at room temperature of 50 to 1,500 kg / cm ² , a strength of 20 to 150 kg / cm ² , and elasticity. Recovery rate 40-75
% Of an amorphous polyolefin obtained by copolymerizing propylene with ethylene and / or butene-1 has an ethylene content of 1%.
-20% by weight, the remainder being propylene, butene-1 content being 1-70% by weight, the remainder being propylene and ethylene content being 1-20% by weight, butene-1 content being 1-70% by weight, the remainder being propylene From an amorphous polyolefin
A resin composition characterized by being selected . 2. An amorphous polyolefin obtained by copolymerizing propylene with ethylene and / or butene-1 has a butene-1 content of 1 to 70% by weight, a balance of propylene and an ethylene content of 1 to 20% by weight. , butene-1 content of 1 to 70 wt%, amorphous polio remainder being propylene
The resin composition according to claim 1, wherein the resin composition is selected from refins . 3. A polyolefin resin containing ethylene as a main component comprises one of an ethylene homopolymer, an α-olefin selected from ethylene and butene-1, hexene-1, 4-methylpentene-1, and octene-1. 3. An ethylene-.alpha.-olefin copolymer obtained by copolymerizing ethylene to vinyl acetate by copolymerizing ethylene and .alpha.-olefin by 1 to 30% by weight. The resin composition as described in the above. 4. A resin composition comprising a commercial or household wrap film, a sheet or film for packaging of fibers and miscellaneous goods, a sheet for construction materials in the civil engineering and construction fields or a base material for a fiber, tape or metal surface protective film; The resin composition according to any one of claims 1 to 3, which is a resin composition for use in pipes, hoses, and laminated materials.