JP3186821B2 - Method for producing polyolefin resin foam and foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyolefin resin foam suitable for use as a sporting goods such as a protector, a building material such as a heat insulating material, or a cushioning material, a packaging material, a car interior material and the like. About the body.

[0002]

2. Description of the Related Art In general, as a method of foaming a polyolefin resin, there are a foaming method of foaming using a thermal decomposition type chemical foaming agent and an extrusion foaming method of foaming using a volatile organic foaming agent. . The volatile organic blowing agents used in the extrusion foaming method are roughly classified into hydrocarbons and halogenated hydrocarbons.

[0003] The former hydrocarbons have a high gas escaping rate through a foamed cell membrane, and therefore are liable to shrink over time, lack dimensional stability, and require a long aging period. There are drawbacks.

Most of the latter halogenated hydrocarbons have the same disadvantages as the above-mentioned hydrocarbons, but the two types of dichlorodifluoromethane (CFC12) and dichlorotetrafluoroethane (CFC14) are not suitable for the aging of foams. Because of its small dimensional change, it has been widely used as a foaming agent for extrusion foaming.

[0005]

However, in recent years, the destruction of the ozone layer by chlorofluorocarbon gas and the biological adverse effects caused thereby have become a major international problem, and the above-mentioned dichlorodifluoromethane and dichlorotetrafluoroethane have become major problems. Hydrogen-free chlorofluorocarbons such as have been designated as substances subject to reduced use or elimination throughout the century.

For this reason, the development of hydrogen-free chlorofluorocarbon substitutes has been actively promoted, and hydrogen-containing chlorofluorocarbons and non-chlorofluorocarbons have been developed.

However, all of them have many problems such as insufficient foaming aptitude and bubble shrinkage due to gas escape, and a foaming agent which can be practically used at present has not yet been developed.

As a method of preventing the shrinkage of air bubbles, a method is known in which an aliphatic ester compound such as stearic acid monoglyceride or an aliphatic amide compound such as stearic acid amide is blended as an anti-shrinkage agent.

However, these effects are difficult to obtain unless the blending amount is relatively large (about 1 to 10 parts by weight with respect to 100 parts by weight of the resin), and if the blending amount is large, the outer lubrication becomes too high. Causing extrusion fluctuations, poor appearance,
Lack of extrusion stability, lowering of discharge pressure, and in some cases, making extrusion impossible or foaming impossible, making it difficult to form large-diameter foam. In addition, the surfactant sometimes floats on the cell surface of the produced foam, and therefore, there has been a problem that the adhesiveness with the same material and other materials is reduced, and the printability is reduced. .

Also, due to skin shrinkage and the like, a polyolefin-based resin foam having a smooth surface suitable for the above-mentioned applications, a small dimensional change with time, and a good appearance cannot be easily obtained.

The present invention has been made to solve such a problem.
According to the first invention, there is provided a high-magnification extruded foam having good appearance, good extruded foaming property, good adhesiveness, good printability, little dimensional change with time, and good appearance. It is an object of the present invention to provide a method for producing a polyolefin resin foam.

A second aspect of the present invention is an external appearance that has a smooth surface and little dimensional change over time, which is suitable for applications such as sports equipment such as protectors, building materials such as heat insulating materials, cushioning materials, packaging materials, and interior materials for automobiles. It is an object of the present invention to obtain a good high magnification polyolefin resin foam.

[0013]

According to a first aspect of the present invention, there is provided a method for producing a polyolefin resin foam, comprising the steps of: adding an aliphatic ester compound or an aliphatic amide compound to a polyolefin resin; Compounded and charged into an extruder, and a foaming agent comprising a hydrogen-containing chlorofluorocarbon having 2 carbon atoms and a hydrogen-containing chlorofluorocarbon having 1 carbon atom is charged into the extruder and extruded and foamed. Is what you do.

[0014] foam second invention, the process for producing a polyolefin resin foam of claim 1 Symbol placement, is characterized in that it is Seise.

The polyolefin resin used in the present invention is a polymer or copolymer of an olefinic hydrocarbon, such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene -Acrylic acid copolymers, propylene-styrene copolymers, propylene-styrene-ethylene-butadiene copolymers, vinyl chloride-ethylene copolymers, and the like. Each of these can be used alone or in combination or cross-linked.

The fluorosurfactant used in the present invention includes, for example, perfluoroalkyl polyether represented by the following formula (1) or (2).

Embedded image (In the formula, m represents an integer of 1 or more, and n represents an integer of 0 or more.)

Embedded image (In the formula, p represents an integer of 1 or more, and q represents an integer of 0 or more.)

The fluorosurfactant can be used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the resin. Preferably, it is used in the range of 0.1 to 1 part by weight.

The blowing agent comprising a hydrogen-containing chlorofluorocarbon having 2 carbon atoms and a hydrogen-containing chlorofluorocarbon having 1 carbon atom, which is used in the first invention, has a former of 70 to 3
It is desirable to use 0% by weight and the latter in a proportion of 30 to 70% by weight.

As the aliphatic ester compound, steric acid monoglyceride, steric acid diglyceride, lauric acid diglyceride, lauric acid monoglyceride, palmitic acid monoglyceride, palmitic acid diglyceride and the like can be used. As the aliphatic amide compound,
Lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, alaxic acid amide, behenic acid amide, stearyl acid stearylamide, N-
Methylsterian acid amide, N-N'-dimethylstearic acid amide, dilauric acid amide, and the like can be used.

When a polyhydric alcohol is added to the water-crosslinkable polyolefin resin, crosslinking proceeds rapidly in the extruder, and a stable foam having a smooth surface cannot be obtained. It is desirable to use an aliphatic amide compound.

A bubble nucleating agent, a crosslinking catalyst, an antioxidant, a lubricant,
Antistatic agents, flame retardants, pigments, and the like can be appropriately added as needed. For example, bubble nucleating agents such as talc, silica, calcium carbonate, calcium stearate, calcium silicate, sodium bicarbonate, or dibutyltin diacetate, dibutyltin dilaurate, stannous acetate, stannous cabrate, tin naphthenate, zinc cabrate, A silanol condensation catalyst such as zinc stearate, or an antioxidant such as a phenol-based, organic thioacid-based, organic phosphoric acid-based, organic amine-based, or organic tin-based can be added.

[0022]

According to the first aspect of the present invention, a hydrogen-containing chlorofluorocarbon, which is easily decomposed by a non-specific substance, is used as a foaming agent without using a foaming agent (chlorofluorocarbon containing no hydrogen) of the ozone depleting specific substance. The risk of destruction of the ozone layer is reduced.

By using a fluorosurfactant in combination with a conventionally used aliphatic ester compound or aliphatic amide compound as a shrinkage preventive, the conventional use of an aliphatic ester compound or aliphatic amide compound is possible. You can reduce the amount you are doing. Thereby, extrusion foaming property, adhesiveness, and printability are improved.

[0024]

EXAMPLES Examples of the present invention and comparative examples will be described below .

Examples 1 to 6 A low-density polyethylene having a melt index (MI: 190 ° C.) of 2.0 and a density of 0.92 was mixed with a fluorosurfactant, stearic acid monoglyceride and talc in the proportions shown in Table 1 . Thereafter, the mixture was supplied to a single-screw extruder having a diameter of 40 mmm and L / D = 28, melt-kneaded, and then fed through a foaming agent inlet provided in the center of the extruder through a hydrogen-containing chlorofluorocarbon having 2 carbon atoms (monochlorodifluoroethane, HCFC).
-142b) and a hydrogen-containing chlorofluorocarbon having 1 carbon atom (monochlorodifluoromethane, HCFC-2
2) and a blowing agent mixed in respective proportions shown in Table 1, so that the expansion ratio becomes 35 times, was injected at a ratio shown in Table 1. After further kneading in the barrel, the mixture was cooled to the optimum foaming temperature at the barrel tip and the mold, and extruded into a predetermined shape from the mold tip. The kneaded resin was discharged from the die tip and foamed at the same time as the polyethylene foam was obtained.

The obtained foam was examined for extrusion stability, appearance, dimensional stability over time, and aging period. The results are shown in Table 1 . Extrusion stability refers to the stability of extrusion foam molding;
Visual observation and aging period: 23 ° C, relative humidity 65%
(RH) The aging period required for foams in a thermo-hygrostat
It is shown. Also, over time dimensional stability by visual observation, the adhesive was compared with the adhesive strength when adhered to the steel by using a predetermined adhesive. The criteria are as follows.

Extrusion stability: good ○ slightly fluctuated × large fluctuation Appearance: ◎ no shrinkage ○ slight skin shrinkage △ shrinkage × large shrinkage dimensional stability over time: ◎ no shrinkage ○ slight skin shrinkage △ shrinkage × shrinkage Large aging period: ◎ None ○ Within 1 day △ Within 3 days × 3 days or more Adhesiveness: ◎ No problem ○ Good △ Poor adhesiveness × Poor adhesiveness (Adhesive strength)> 1600 1500-1600 1400-1500 <1400 ( (gf / 25mm)

[0028] except not using the Comparative Examples 1 to 6 fluorine based surfactant, Examples 1-6
The same low-density polyethylene resin, stearic acid monoglyceride, talc, HCFC-142b and, HCFC-22
, And blended in the proportions shown in Table 1 to produce polyethylene foams in the same manner as in Examples 1 to 6 . The results are shown in Table 1 . Evaluation items and evaluation methods are the same as those in Examples 1 to 6 .

[0029]

[Table 1]

[0030] As can be seen 1 or al table, a fluorine-based surfactant, when used in combination with aliphatic ester compound, in amounts and of small additions of 0.1 wt% of fluorine-based surface active agent itself, extrusion stability The properties, appearance, dimensional stability over time, and aging period were improved.

Usually, the amount of the aliphatic ester compound which is not effective unless the blending amount is relatively large (about 1 to 10 parts by weight with respect to 100 parts by weight of the resin) is 0.5 to 0.9% and 1%.
%, The extrusion stability, appearance, dimensional stability over time, and aging period were improved by the combined use with a fluorosurfactant.

On the other hand, when the fluorosurfactant is not used in combination with the aliphatic ester compound, when the amount of the aliphatic ester compound is reduced, the extrusion stability and adhesiveness are good, but the appearance, The dimensional stability over time and the aging period deteriorated. Conversely, when the amount of the aliphatic ester compound was increased, the appearance, the dimensional stability over time, and the aging period were good, but the extrusion stability and the adhesiveness were deteriorated. Therefore, none satisfying all of extrusion stability, adhesiveness, appearance, dimensional stability with time, and aging period could be obtained.

Examples 7 to 9 show examples of the water-crosslinkable polyethylene in the first invention. In the case of the crosslinkable polyethylene, as described above, when a polyhydric alcohol is added to the crosslinkable polyethylene, the crosslinking proceeds rapidly in the extruder, and a smooth foam having a smooth surface cannot be obtained. A group amide compound was used.

Examples 7 to 9 Crosslinkable low-density polyethylene having a melt index (MI; 190 ° C.) of 2.0 and a density of 0.92, a fluorine compound,
Using stearic acid amide, talc, dibutyltin dilaurate, HCFC-142b and HCFC-22, Table 2
And a crosslinkable polyethylene foam was produced in the same manner as in Examples 1 to 6 .

Table 2 shows the results of examining the extruded foamability, appearance, dimensional stability over time, aging period, and adhesiveness of the obtained foam. Evaluation items and evaluation methods are the same as those in Examples 1 to 6 .

[0036] except not using the Comparative Examples 7-9 fluorine-based surfactant, Examples 7-9
The same crosslinkable low density polyethylene, stearic amide, talc, dibutyltin dilaurate and, HCFC-14
2b and HCFC-22 were blended in the proportions shown in Table 2 to produce a crosslinkable polyethylene foam in the same manner as in Examples 7 to 9 .

Table 2 shows the results of examining the extruded foamability, appearance, dimensional stability over time, aging period, and adhesiveness of the obtained foam. Evaluation items and evaluation methods are the same as those in Examples 7 to 9 .

[0038]

[Table 2]

[0039] As can be seen 2 or al table, when the crosslinkable polyethylene also become same results as non-crosslinked polyethylene described above, when used in combination with the fluorine-based surfactant and an aliphatic amide compound, extrusion stability The properties, appearance, dimensional stability over time, and aging period were improved.

On the other hand, when the fluorosurfactant and the aliphatic amide compound are not used in combination, when the amount of the aliphatic amide compound is reduced, the extrusion stability and adhesiveness are good, but the appearance, The dimensional stability over time and the aging period deteriorated.

Conversely, when the amount of the aliphatic amide compound is increased, the appearance, the dimensional stability with time and the aging period are good, but
Extrusion stability and adhesion deteriorated. Therefore, extrusion stability,
A product satisfying all of the adhesiveness, appearance, dimensional stability over time, and aging period could not be obtained.

[0042]

According to the first aspect of the present invention, a foaming agent of a specific substance that depletes ozone (chlorofluorocarbon containing no hydrogen) is used.
Since the hydrogen-containing chlorofluorocarbon, which easily decomposes a non-specific substance, is used as a foaming agent without using, it is possible to reduce the risk of destruction of the ozone layer and to contribute to pollution prevention.

By using the fluorosurfactant of the first invention together, the compounding amount of the conventionally used aliphatic ester compound or aliphatic amide compound of the anti-shrinkage agent does not affect the extrusion foaming property. In addition, since it can be reduced to a place where the influence of adhesiveness and printability is small, extrusion foaming property, adhesiveness, good printability, little dimensional change with time,
A polyolefin resin foam having a good appearance and a high magnification can be produced.

According to the second aspect of the present invention, the outer appearance is suitable for applications such as sports equipment such as protectors, building materials such as heat insulating materials, cushioning materials, packaging materials, and interior materials for automobiles, and has a small dimensional change with time. A good high magnification polyolefin-based resin foam can be obtained.

Claims (2)

(57) [Claims] (1) An aliphatic esthetic resin is added to a polyolefin resin.
Compound or aliphatic amide compound and a fluorine-based surfactant
And an extruder, and this is put into an extruder, which has 2 carbon atoms.
Hydrogen-containing chlorofluorocarbon and C1 hydrogen
A blowing agent consisting of chlorofluorocarbon and
Characterized by being extruded and foamed
A method for producing a fin-based resin foam. 2. The polyolefin resin according to claim 1,
It is manufactured by the method of manufacturing foam
Foam. [0001]