JP2001279019A - Thermoplastic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition improved in oil, weather and blocking (sticking) resistances without deteriorating functions as a thermoplastic elastomer. SOLUTION: This thermoplastic elastomer composition is obtained by compounding 100 pts.wt. of an uncross-linked butadiene or isoprene homopolymer or a random copolymer thereof and a styrene-based compound or isoprene or an acrylic ester compound, etc., having >=50 wt.% ratio of the butadiene or isoprene with 50-150 pts.wt. of a polyethylene resin having <=120 deg.C melting point or/and softening point and <=4.0 value of Q of molecular weight distribution index (weight-average molecular weight/number-average molecular weight).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0101]

TECHNICAL FIELD The present invention relates to a non-crosslinked homopolymer of butadiene or isoprene, or a random copolymer with a styrene compound or an isobutylene or acrylate compound having a butadiene or isoprene ratio of 50% by weight or more. The present invention relates to a thermoplastic elastomer composition having a polymer, a melting point or a softening point of 120 ° C. or less, and a polyethylene resin having a narrow molecular weight distribution, which is rich in flexibility, and excellent in weather resistance, oil resistance, blocking properties, and moldability.

[0092]

2. Description of the Related Art Homopolymers of butadiene or isoprene and random copolymers of butadiene or isoprene and styrene monomers are widely used as synthetic rubbers. However, these synthetic rubbers have disadvantages in quality such as oil resistance, weather resistance and ozone resistance. A drawback in handling is blocking property (adhesion). As a countermeasure against these problems, crosslinking is a measure against oil resistance. If this is not possible, oil-resistant rubber must be used. The main measures against weather resistance include the use of an ultraviolet absorber and a light stabilizer and the hiding effect of a pigment, and the ozone resistance measures include the use of an ozone deterioration inhibitor. In any case, the number of steps is increased, and expensive additives are used, which causes a cost increase. Furthermore, when the raw material is block-shaped with respect to blocking properties (adhesion), a polyethylene film is sandwiched or powder is shaken on the surface, but there is no drastic measure at present.

[0093]

An object of the present invention is to provide a composition having improved oil resistance, weather resistance and blocking property (adhesion), which are disadvantages without impairing the function as a thermoplastic elastomer.

[0093]

Means for Solving the Problems A homopolymer of butadiene or isoprene or a random copolymer with a styrene compound or an isobutylene or acrylate compound having a butadiene or isoprene ratio of 50% by weight or more is 100% by weight. Parts, the melting point or the softening point is 120 ° C. or less and the molecular weight distribution index Q
The composition obtained by adding 50 to 150 parts by weight of a polyethylene resin having a value (weight average molecular weight / number average molecular weight) of 4.0 or less is extremely excellent in oil resistance, weather resistance, and blocking (adhesive) moldability. It led to the present invention.

[0056]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic elastomer used in the present invention is a homopolymer of non-crosslinked butadiene or isoprene, a natural rubber as an isoprene polymer, and a styrene compound having a butadiene or isoprene ratio of 50% by weight or more. And styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), and butyl rubber which is a random copolymer with isobutylene.

Those having a butadiene or isoprene ratio of 50% by weight or less lack flexibility, have poor compatibility with polyethylene resins, and do not function as thermoplastic elastomers.

The polyethylene resin used in the present invention is typically an ethylene homopolymer having a melting point or softening point of 120 ° C. or less and a molecular weight distribution index Q value of 4.0 or less, or ethylene and acrylate, and vinyl acetate. And a copolymer with a C3-C10 α-olefin or the like. Particularly, a copolymer with an α-olefin using a metallocene catalyst is preferably used because it has low stickiness and adhesion, has moderate elasticity and flexibility, and has good compatibility.

These polyethylene resins are added in an amount of 50 to 150 parts by weight based on 100 parts by weight of the thermoplastic elastomer. If the amount is less than 50 parts by weight, the blocking property cannot be prevented,
In addition, improvements in oil resistance and weather resistance are not sufficient. If the amount is more than 150 parts by weight, the function as an elastic body, for example, the quality such as compression set and rebound resilience is deteriorated, and the elastic body does not function. Further, heat resistance is extremely reduced.

Further, by adding appropriate amounts of various fillers and extenders, the blocking property and the moldability can be improved. For example, examples of the inorganic filler include calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, alumina, talc, clay, diatomaceous earth, and activated clay. Examples of the organic filler include wood flour, starch, cereal powder, bone flour and the like.

The addition amount is at most 200 parts by weight with respect to 100 parts by weight of the thermoplastic elastomer, and if it is more than 200 parts by weight, the rubbery elastic function is impaired.

In the composition of the present invention, antioxidants, light stabilizers, nucleating agents, lubricants, antistatic agents, antifogging agents, antiblocking agents, which are usually added to polyethylene resins and thermoplastic elastomers, A dispersant such as a flame retardant, a pigment, a metal soap or a neutralizing agent may be used in combination within a range not to impair the object of the present invention.

To the resin composition of the present invention, a predetermined amount of the above-mentioned additive is further added, and when the thermoplastic elastomer is in a block form, it is usually kneaded with a Banbury mixer or a roll or the like to form a film by a calender molding method. And granulated by a sheet cutter for final use. When the thermoplastic elastomer is crumb or pellet, a conventional mixing device such as a Henschel mixer (trade name), a super mixer,
The mixture is mixed using a ribbon blender or the like, and is directly or granulated, and then subjected to an injection molding method, an extrusion molding method, a blow molding method, and a calender molding method to produce a target molded product. The granulation is performed by a usual single-screw extruder, twin-screw extruder, multi-screw extruder, or the like. The processing temperature is 140 ° C or lower, preferably 80 to 130 ° C.

[0113]

Embodiments 1 and 2

Comparative Examples 1 and 2 Polybutadiene rubber (JSR Corporation)
(BR01), 100 parts by weight of a polyethylene resin polymerized with a metallocene catalyst (Affinity PL1880, trade name, manufactured by Dow Plastics, melting point 100)
° C, melt index 1.0, Q = 2.2)
After weighing 0, 60, 120, and 200 parts by weight, the mixture was put into an 8-inch roll heated to 110 ° C., kneaded for 5 minutes, and taken out as a sheet having a thickness of about 1 mm. After visual observation of this sheet, it was formed into a sheet having a thickness of 2 mm by a hot press (130 ° C.). Using this sheet, oil resistance, weather resistance, blocking resistance, compression set, and hardness were measured. Table 1 shows the results.

[0141]

[Evaluation of the roll sheet surface] Visual observation of the surface condition of the sheet taken out from the 8-inch roll Surface smoothness: ○, slight unevenness; △, rough surface; ×

[0151]

[Evaluation of oil resistance] Measured for swelling after immersion for 7 hours at 50 ° C using No. 3 oil according to JIS K6301

[0162]

[Evaluation of weather resistance] Based on JIS K6266, visual observation after irradiation with sunshine weatherometer for 500 hours, no discoloration, cracks, cracks; ○, discoloration, cracks, cracks; ×

[0173]

[Evaluation of anti-blocking property] Two sample sheets of 100 × 100 × 2 mm were stacked, sandwiched between glass plates, placed on a 1 kg weight, left at room temperature (25 ° C.) for 24 hours, and then peeled off by hand without sticking; ○, slightly sticky but no surface destruction upon peeling;
△, surface destruction upon peeling; ×

[0182]

[Evaluation of compression set] Based on JIS K6301, 70
℃, 22 hours Permanent strain rate of 50% or more is judged to have no function as an elastomer

[0119]

[Evaluation of hardness] Based on JIS K6301, using A-type hardness meter

[0202]

Comparative Example 3 100 parts by weight of the polybutadiene rubber used in Examples 1 and 2 was mixed with soft polyethylene (product name: NUC FLX DFDB-1085N, manufactured by Nippon Unicar Co., Ltd.).
T, melting point 118 ° C., melt index 1.0, Q =
4.2) 100 parts by weight were simultaneously charged into an 8-inch roll heated to 110 ° C., and the same sample preparation and physical property evaluation as in Examples 1 and 2 were performed. The results are shown in Table 1.

[0219]

Comparative Example 4 100 parts by weight of the polybutadiene rubber used in Examples 1 and 2 was mixed with low-density polyethylene (Mitsui Nisseki, F102, melting point 125 ° C., melt index 1.
0, Q = 9.0) 100 parts by weight heated to 130 ° C. 8
The sample was simultaneously charged into an inch roll, and the same sample preparation and physical property measurement as in Examples 1 and 2 were performed. The results are shown in Table 1.

[0222]

Example 3 Polyisoprene rubber (JSR, JSR
IR2200) to 100 parts by weight of the metallocene-based polyethylene (affinity PL1) used in Examples 1 and 2.
880) 100 parts by weight were simultaneously charged into an 8-inch roll heated to 110 ° C., and the same sample preparation and physical property measurement as in Examples 1 and 2 were performed. The results are shown in Table 2.

[0230]

Example 4 Styrene-butadiene rubber (manufactured by JSR,
(JSR1500) 100 parts by weight with respect to the metallocene polyethylene (affinity PL) used in Examples 1 and 2.
1880) 100 parts by weight were simultaneously charged into an 8-inch roll heated to 120 ° C., and the same sample preparation and physical property measurement as in Examples 1 and 2 were performed. Table 2 shows the results.

[0242]

Embodiments 5 and 6

Comparative Example 5 Polybutadiene rubber (BR0 manufactured by JSR Corporation)
1) 100 parts by weight of 100 parts by weight of metallocene-based polyethylene (affinity PL1880), 50, 15 parts of calcium carbonate (SL1000 manufactured by Nitto Powder Chemical Co., Ltd.)
0,250 parts by weight were added and mixed, and the same sample preparation and physical property measurement as in Examples 1 and 2 were performed. Table 2 shows the results.

[0252]

[Table 1]

[0262]

[Table 2]

Claims (3)

[Claims] A non-crosslinked homopolymer of butadiene or isoprene or 100 parts by weight of a random copolymer with a styrene compound or an isobutylene or acrylate compound having a butadiene or isoprene ratio of 50% by weight or more. On the other hand, melting point or softening point is 1
There is no blocking (adhesion) obtained by blending 50 to 150 parts by weight of a polyethylene resin having a molecular weight distribution index Q value (weight average molecular weight / number average molecular weight) of 4.0 or less at 20C or less, and has a weather resistance and an oil resistance. Excellent thermoplastic elastomer composition. 2. The thermoplastic elastomer composition according to claim 1, wherein the polyethylene resin is a polyethylene resin polymerized by a metallocene catalyst. 3. The thermoplastic elastomer composition according to claim 1, further comprising an inorganic filler or an organic filler in an amount of up to 200 parts by weight based on 100 parts by weight of the thermoplastic elastomer.