JPH11263863A - Polyolefin resin foam and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyolefin resin foam which hardly causes precipitation in a fogging test and does not emit an odor by adding a fogging and odor inhibitor to a foamable polyolefn resin, molding the resultant compsn. into a desired shape, and foaming it. SOLUTION: A foamable polyolefn resin prepd. by adding 2-25 pts.wt. blowing agent (e.g. azodicarbonamide) to 100 pts.wt. polyolefin resin is compound with 0.05-5 pts.wt., pref. 0.1-1 pt.wt., fogging and odor inhibitor (e.g. a porous carbon black having an average particle size of 20-150 μm) and optionally further with a flame retardant, a colorant, an antioxidant, a filler, a blowing aid, a lubricant, a crosslinking aid, etc. The resultant compsn. is molded into a desired shape, if necessary is crosslinked by the exposure to an electron beam, and is heated to the decomposition point of the blowing agent or higher to be foamed, thus giving a polyolefin resin foam having a degree of crosslinking of 30-70%, pref. 50-60%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin foam and a method for producing the same, and more particularly to a polyolefin resin foam having a small amount of crystals in a fogging test and a low odor, and a method for producing the same.

[0002]

2. Description of the Related Art Polyolefin resin foams, when used, for example, in interior materials for vehicles (for example, when used with vinyl chloride sheets), are formed by deposits such as by-products generated by decomposition of a foaming agent. Cloudy (cloudy) (hereinafter referred to as "fogging")
There is a problem. In particular, polyolefin resin foam using azodicarbonamide as a foaming agent,
There is such a problem.

[0003] In addition to the fogging problem, there is a problem of odor, particularly in a vehicle room or the like where the temperature is high, for example, in summer. It is considered that this odor is mainly caused by the skin material, for example, when the skin material is a soft polyvinyl chloride sheet, the plasticizer and the ammonia component coming out of the foamed body generate the odor.

Conventionally, there has been no effective means for solving such problems relating to fogging and odor by one method, for example, by one additive.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyolefin resin foam having a small amount of precipitates in a fogging test and a low odor, and a method for producing the same. Is to do.

[0006]

In order to solve the above-mentioned problems, a polyolefin resin foam according to the present invention is characterized by containing a fogging / odor control agent. This fogging / odor suppressant can suppress fogging and odor at the same time while being a kind of suppressant. Typically, carbon black can be used.

The method for producing a polyolefin resin foam according to the present invention is characterized in that a fogging / odor control agent is added to a foamable polyolefin resin, and the resin composition is molded into a predetermined shape and then foamed. It consists of a method.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with preferred embodiments.

According to the present invention, a fogging / odor control agent is added to a polyolefin-based resin foam, and substances which cause precipitates generated by decomposition of the foaming agent are reduced by the inhibitor, thereby reducing the fogging test. This reduces the amount of precipitates generated, and at the same time reduces substances that cause odor.

[0010] That is, the present invention is a polyolefin-based resin foam which contains a fogging / odor control agent in the foam resin, generates a small amount of precipitates in a fogging test, and has a low odor.

The olefin resin in the present invention includes, for example, polyethylene resins having low density, medium to high density, linear low density, etc., ethylene and vinyl acetate, or
Alkyl acrylates, copolymers with propylene and the like, homo- or copolymerized polypropylenes, chlorinated polyethylenes and the like can be used alone or as a mixture.

As the foaming agent used in the present invention, for example, azodicarbonamide is used.
Although it is appropriately adjusted depending on a desired expansion ratio, it is generally in a range of 2 to 25 parts by weight based on 100 parts by weight of the resin.

As the fogging / odor control agent used in the present invention, carbon black is typically used. Among them, carbon black having an average particle diameter of 20 to 150 μm is preferable, and carbon black having an average particle diameter of 50 μm or less is more preferable. In particular, porous carbon black is more preferable because the adsorption surface area can be increased.

The content of carbon black is preferably in the range of 0.05 to 5 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the polyolefin resin.

When carbon black is contained as a fogging / odor control agent, precipitates that cause fogging are physically adsorbed, and urea and the like that cause odors are also adsorbed. Both odors are suppressed at the same time.

The method of adding the fogging / odor control agent used in the present invention is not particularly limited.
Preferably, it is added in the form of pellets containing an inhibitor.

To the foamable resin composition sheet, an appropriate amount of a flame retardant, a coloring agent, an antioxidant, a filler, a foaming aid, a lubricant, a crosslinking aid, and the like can be added as required.

The present invention can also be applied to a crosslinked polyolefin resin foam. In the case of forming a crosslinked foam, it is generally carried out by a method using an electron beam or a chemical crosslinking using an organic peroxide such as dicumyl peroxide. Although a method can be adopted, an electron beam irradiation method or a chemical cross-linking method using a resin obtained by grafting or copolymerizing a cross-linking reactive vinylmethoxysilane or the like to the resin can also be applied. Further, various crosslinking methods may be used in combination.

The degree of crosslinking is preferably 30 to 70%, more preferably 50 to 60%.

Such a polyolefin resin foam according to the present invention is suitable for a vehicular interior material in which fogging and odor are problematic.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Fogging and odor in the implementation were evaluated by the following methods. (1) Fogging test Using a HAAKE fogging test apparatus, 100 ° C.
After heating for 3 hours, it was cooled at room temperature for 1 hour. The sample was tested with a 0.6 mm vinyl chloride sheet adhered to one side and the vinyl chloride sheet side up. The presence or absence of the precipitate was observed under a microscope of 50 times.

(2) Odor "Research Report on Measurement of Odorous Substances" commissioned by the Environment Agency in 1979 (Japan Environmental Health Center)
The odor intensity was determined by a five-point measurement method described on pages 48 to 250. The closer to rank 1, the lower the odor intensity, and the closer to rank 5, the higher the odor intensity.

Examples 1 to 5 80 parts by weight of a propylene resin (melt index 2.0) obtained by random copolymerization of propylene with 4% by weight of ethylene and 20 parts by weight of low density polyethylene (density 0.915, melt index 8.0) Parts by weight of azodicarbonamide as a foaming agent, 4 parts by weight of divinylbenzene as a crosslinking aid, and "Irgnox" 1010 as a heat stabilizer.
0.2 parts by weight of a carbon black having an average particle size of 50 μm as a fogging / odor control agent.
The mixture was adjusted to 0.5, 1.0, 3.0, and 5.0 parts by weight, and preliminarily mixed with a Henschel mixer.
The mixture was charged into a single screw extruder (L / D = 25), kneaded and extruded while adjusting the average resin temperature to 180 ° C. or lower so that the foaming agent was not decomposed, and extruded from a T-die, each having a thickness of 1.75 m.
Five types of foamable resin composition sheets having a width of 410 mm and a width of 410 mm were formed.

Next, each foamable resin composition sheet was irradiated with an electron dose of 5 Mrad using an electron beam irradiator (800 kV) to crosslink, thereby obtaining a foamable resin composition crosslinked sheet.

Next, each foamable resin composition sheet is placed in a foaming apparatus at a temperature of about 230 to 2 which is higher than the decomposition temperature of the foaming agent.
Heating to 40 ° C. produced a crosslinked foam.

Comparative Example 1 A foam was produced in the same manner as in the above example except that no fogging / odor control agent was contained.

With respect to the six types of foams, the amount of precipitates and the odor were examined by the fogging test described above.
Table 1 shows the results.

[0028]

[Table 1]

Examples 6 to 8 80 parts by weight of a propylene resin (melt index 2.0) obtained by random copolymerization of propylene with 4% by weight of ethylene and 20 parts by weight of low density polyethylene (density 0.915, melt index 8.0) 5, 10 and 15 parts by weight of azodicarbonamide as a foaming agent, 4 parts by weight of divinylbenzene as a crosslinking aid, and "I" as a heat stabilizer.
RGNOX "1010 was added in an amount of 0.2 part by weight, carbon black having an average particle diameter of 50 μm was adjusted to 5.0 parts by weight as a fogging / odor suppressant, and premixed with a Henschel mixer. The mixture was mixed with a 90 mmφ single screw extruder (L). / D =
25), kneaded and extruded while adjusting the average resin temperature to 180 ° C. or lower so that the foaming agent is not decomposed, and extruded from a T-die to obtain a foamable resin composition sheet having a thickness of 1.75 mm and a width of 410 mm. Type molded.

Next, each foamable resin composition sheet was irradiated with an electron dose of 5 Mrad using an electron beam irradiator (800 kV) to crosslink, thereby obtaining a foamable resin composition crosslinked sheet.

Next, each foamable resin composition sheet is placed in a foaming apparatus at a temperature of about 230 to 2 which is higher than the decomposition temperature of the foaming agent.
Heating to 40 ° C. produced a crosslinked foam.

Comparative Examples 2 to 4 Except that no inhibitor was contained, foams were produced in exactly the same manner as in Examples 6 to 8.

With respect to the above six types of foams, the presence of precipitates and the odor were examined by the aforementioned method. Table 2 shows the results.

[0034]

[Table 2]

Examples 9 to 11 4 parts by weight of propylene with ethylene 80 parts by weight of a propylene resin (melt index 2.0) obtained by random copolymerization, 20 parts by weight of low density polyethylene (density 0.915, melt index 8.0) Parts by weight of azodicarbonamide as a foaming agent, 4 parts by weight of divinylbenzene as a crosslinking aid, and "Irgno" as a heat stabilizer.
x "1010 was added in an amount of 0.2 part by weight, and carbon black having an average particle size of 50 m was used as a fogging / odor control agent.
0 parts by weight, pre-mixed with Henschel mixer,
The mixture is put into a 90 mmφ single screw extruder (L / D = 25), and the average resin temperature is set to 180 ° C. so that the foaming agent is not decomposed.
The following adjustments were made, kneaded and extruded, and extruded from a T-die to form foamable resin composition sheets each having a thickness of 1.75 mm and a width of 410 mm.

Next, each of the foamable resin composition sheets was treated with an electron beam irradiator (800 kV) to obtain 3, respectively.
The crosslinked sheet was irradiated with an electron dose of 5.7 Mrad to form a crosslinkable resin composition crosslinked sheet.

Next, each foamable resin composition sheet is placed in a foaming apparatus at a temperature of about 230 to 2 which is higher than the decomposition temperature of the foaming agent.
Heating to 40 ° C. produced a crosslinked foam.

Comparative Examples 5 to 7 Foams were produced in exactly the same manner as in Examples 9 to 11, except that no inhibitor was contained.

With respect to the above six types of foams, the presence or absence of precipitates and the odor were examined by the above-described method. Table 3 shows the results.

[0040]

[Table 3]

As is apparent from Tables 1 to 3, both fogging and odor can be suppressed well by containing carbon black as a fogging / odor suppressing agent.

[0042]

According to the present invention, a polyolefin resin foam contains a fogging / odor control agent to produce a foam having a reduced amount of precipitates and a reduced odor in a fogging test. Can be.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 23/10 C08L 23/10 // B29C 47/14 B29C 47/14 B29K 23:00 27:00 105: 04 105: 24 B29L 7:00 31:58

Claims (10)

[Claims] 1. A polyolefin-based resin foam containing a fogging / odor control agent. 2. The method according to claim 1, wherein the inhibitor has an average particle size of 20 to 150 μm.
The polyolefin-based resin foam according to claim 1, comprising carbon black. 3. The polyolefin resin foam according to claim 1, wherein said inhibitor comprises porous carbon black. 4. The method according to claim 1, wherein the inhibitor is a polyolefin resin.
0.1 to 15 parts by weight with respect to 00 parts by weight,
The polyolefin resin foam according to any one of claims 1 to 3. 5. The polyolefin resin foam according to claim 1, wherein the main component is polypropylene. 6. The polyolefin resin foam according to claim 1, which is a crosslinked foam. 7. The polyolefin resin foam according to claim 1, which is used for an interior material for a vehicle. 8. A method for producing a polyolefin-based resin foam, comprising adding a fogging / odor control agent to a foamable polyolefin-based resin, molding the resin composition into a predetermined shape, and then foaming the resin composition. 9. The method for producing a polyolefin resin foam according to claim 8, wherein carbon black is used as said inhibitor. 10. The method for producing a polyolefin resin foam according to claim 8, wherein the main component of the expandable polyolefin resin is polypropylene.