JP2003171507A - Polyolefin-based resin composition having ability to expand and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyolefin-based resin composition having ability to expand which particularly excels in heat resistance and has properties such as recycling properties and can select an expanded structure and a molding method having a high degree of freedom when inserted into a specified space or joined to another article, heated and expanded in various processings to form an expanded structure. <P>SOLUTION: The polyolefin-based resin composition having the ability to expand is constituted of a resin composition obtained by melt kneading at least two kinds of resins of (A) a polyolefin-based resin having a melting point (Tma) of ≤100°C and (B) a polyolefin-based resin having a melting point (Tmb) of >100°C and a powdered blowing agent having an expanding initiation temperature of 100-180°C, and has the ability to expand to form an expanded structure by inserting the resin composition into a specified space or joining the resin composition and another article, and heating and expanding the resin composition in such a state and having an energy (Ea) of the crystal fusion at ≤100°C of a foam obtained by heat-processing the resin composition of 20-100 mJ/mg and, simultaneously, an energy (Eb) of the crystal fusion at ≥120°C of 10-150 mJ/mg. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyolefin resin composition having a foaming ability and a method for producing the same. More specifically, it is applied to building insulation materials, industrial materials, furniture, household appliances, heat / cool boxes, cushioning materials such as automobile interior materials, fillers, heat insulating materials, etc. The present invention relates to a polyolefin resin composition having a foaming ability which is bonded to other articles and heat-foamed under various processes to form a foamed structure.

[0002]

2. Description of the Related Art Foams having closed cells are lightweight and have excellent cushioning properties and heat insulating properties, and are used in a wide variety of fields. On the other hand, polyurethane injection foaming has excellent processability, and the foam can be supplied at the same time as molding, and the foamed structure corresponding to various shapes can be manufactured by a simplified processing step. In addition, in various shapes, it has excellent adhesiveness to the composite material, and the characteristics of the foam, such as cushioning properties, filling properties, and heat insulating properties, are fully utilized. However, there were problems in terms of disposal and recycling.

Japanese Patent Publication No. 6-96273 discloses a cross-linking degree as a method of forming a foamed structure having excellent adhesiveness such as injection foaming of polyurethane by using a polyolefin resin foam which is superior in terms of disposal and recycling. A method of press molding elevated foam with molten resin is disclosed.
However, although the adhesion is good with this method, by increasing the degree of cross-linking of the foam, the range of molding application is limited to shapes with less height difference due to the decrease in elongation, and remelting due to increase in melt viscosity. It has drawbacks such as difficulty in extrusion and poor recyclability.

Further, in Japanese Patent Publication No. 7-45197, a polyolefin foaming resin is kneaded with a chemical foaming agent which generates gas by thermal decomposition, an organic peroxide and the like, formed into a sheet and then laminated with a synthetic resin sheet, and then heated. There is disclosed a method of foaming and immediately performing vacuum molding and press molding simultaneously to obtain a molded body. However, when heated vertically
It is difficult to hold a foam that swells in the lateral and thickness directions at the same time, and the application of this example is limited to a low expansion ratio in which the change in foam volume during foaming is small. Therefore, heat insulation, cushioning,
Not only is it inferior in lightness, but the foam stretched at the time of molding is partially thinned, so that the heat insulating property and the buffer property are not uniform. In order to avoid this, there is a drawback that the applicable range is limited to a shape with a small height difference.

Further, in JP-A-8-192436, a polyolefin resin blended in a specific combination is mixed with an azodicarbonamide or sodium bicarbonate foaming agent, an organic peroxide crosslinking agent and a specific flame retardant, A molding method is disclosed in which a foam is integrally formed with the skin by a molding method limited to the powder slush molding method. However, it is difficult to obtain a closed cell foam having a uniform cell shape by this molding method. This is because in order to form uniform bubbles, the resin is first softened by heating, and then the resin is decomposed by the organic peroxide to crosslink the resin to give it an appropriate viscosity to hold the foaming gas, and the pyrolysis foaming. The order is such that the agent decomposes to form closed cells, but it does not use the powdered raw material of the resin composition obtained by melt-kneading the resin, the foaming agent, the crosslinking agent, etc. In the composition of the above, because the softening and decomposition start from the portion existing near the heat source, the above order is not satisfied, uniform bubble formation,
It is difficult to obtain a foam having a high expansion ratio.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks by inserting a polyurethane resin into a predetermined space which can be substituted and functions as a cushioning material, a filling material, and a heat insulating material in various applications, or The present invention provides a polyolefin-based resin composition having a foaming ability, which is bonded to the article described above and is heat-foamed under such a state to form a foamed structure, and a method for producing the same.

Since the resin composition has heat resistance, excellent recyclability, and has various shapes, a foamed structure and a processing method are selected which have a high degree of adhesion and a high degree of freedom in processing involving heating. It is a polyolefin-based resin composition having a possible foaming ability.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyolefin resin having a foaming ability which is inserted into a predetermined space or is joined to another article to form a foamed structure by heat foaming under such a condition. A resin composition mainly containing a powdery foaming agent having a foaming initiation temperature by heat of 100 to 180 ° C., and having a plate shape, a chip shape, a powder shape, or a mixture thereof. The polyolefin-based resin (A) having a crystal melting peak (melting point Tma) of 100 ° C. or lower, which constitutes the composition, and 10
Of a DSC curve obtained by differential scanning calorimetry analysis of a foam which is composed of at least two kinds of resin including a polyolefin resin (B) having a crystal melting peak (melting point Tmb) exceeding 0 ° C. Among the crystal melting energies per unit weight obtained from the crystal melting peak area, the crystal melting energy (Ea) at 100 ° C. or lower is 20
˜100 mJ / mg and a crystal melting energy (Eb) at 120 ° C. or higher of 10 to 150 mJ / mg, which is achieved by a polyolefin resin composition having a foaming ability.

Further, in the method for producing a polyolefin resin composition having the above foaming ability, at least two kinds of the above-mentioned polyolefin resins (A) and (B) and a powdery foaming agent are added to the polyolefin resin (A). A resin composition melt-kneaded at a crystal melting peak (melting point Tma) or more and less than a foaming start temperature due to heat of the foaming agent is formed into a plate shape, a chip shape, or a powder shape in a subsequent step. To do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin resin used in the polyolefin resin composition having the foaming ability of the present invention is a polymer or copolymer of olefinic hydrocarbon. Such a resin has a crystalline melting peak (melting point Tma) of 100 ° C. or less in order to suppress decomposition and expansion of the powdery foaming agent due to heat and to satisfy the heat resistance of the resulting foam (A). And a polyolefin resin (B) having a crystal melting peak (melting point Tmb) of more than 100 ° C., the crystalline melting energy (Ea) of 100 ° C. or less of the obtained foam is within a specific range. To improve the accuracy of suppressing the decomposition and expansion of the powdery foaming agent due to heat at the time of adjusting the composition involved in poor appearance and foaming failure, and in improving the thermal characteristics of the foamed material. It is necessary to limit the crystal melting energy (Eb) at 120 ° C. or higher to a specific range.

The polyolefin resin used in the polyolefin resin composition having the foaming ability of the present invention is 100
Consist of at least two kinds of resins: a polyolefin-based resin (A) having a crystal melting peak (melting point Tma) of 100 ° C or lower and a polyolefin-based resin (B) having a crystal melting peak (melting point Tmb) of higher than 100 ° C. Is required, and the polyolefin resin (A) is 100 ° C.
The following polyethylene-based resins having a large amount of crystal melting energy are preferable, and the polyolefin-based resin (B) is 120
A polyethylene resin, a polypropylene resin, or a mixture thereof, which has a large amount of crystal melting energy at or above 0 ° C., is preferable.

Further, the crystalline melting energy per unit weight obtained from the crystalline melting peak area of the DSC curve measured by differential scanning calorimetry of the foam obtained by heat-processing the polyolefin resin composition having the foaming ability. Of which 1
When the powdery foaming agent is melt-kneaded, the crystal melting energy (Ea) of 00 ° C. or lower is low at the processing temperature so that the foaming agent does not cause defective appearance or foaming failure due to foaming such as decomposition or expansion due to heat. The crystal melting energy (Eb) of 120 ° C. or higher, which is also measured by the above-mentioned method, is to impart heat resistance when heat-processed to form a foam. Crystal melting energy (Ea) is 20 to 100 mJ / mg,
And the crystal melting energy (Eb) is 10 to 150 m
It is limited to J / mg, preferably the crystal melting energy (Ea) is 25 to 60 mJ / mg, and the crystal melting energy (Eb) is 20 to 100 mJ / mg.

The crystal melting energy (Ea) is 20 mJ
If it is less than / mg, the temperature of the heat applied when the resin composition having the foaming ability is melt-kneaded and the temperature rise due to heat generation by shearing occur, and a bubble nucleus such as decomposition or expansion due to heat of the powdery foaming agent is formed. When the composition is inferior in appearance, or when the composition is heat-processed to form a foam, a foaming ratio that impairs basic foam properties such as cushioning properties and heat insulation properties. In some cases, a foam having a good cell shape may not be obtained, and if the crystal melting energy (Ea) exceeds 100 mJ / mg, there is no foaming such as decomposition or expansion of the foaming agent to form a cell nucleus. It is possible to melt-knead the composition, but when the composition is heat-processed to form a foam, the heat resistance is remarkably reduced, which may be impractical. Further, if the crystal melting energy (Eb) is less than 10 mJ / mg, the heat resistance of the resin composition having a foaming ability is remarkably lowered when it is formed into a foam, which may be impractical. If the crystal melting energy (Eb) exceeds 150 mJ / mg, the temperature of the heat applied when the composition is melt-kneaded and the temperature rise due to shear heat generation occur, and the powdery foaming agent decomposes or expands due to heat. Since the frequency of foaming to form cell nuclei is significantly increased, the appearance of the composition is inferior, and when the composition is heat-processed to form a foam, basic foam properties such as buffering properties and heat insulating properties are impaired. Such a foaming ratio may not be achieved or a foam having a good cell shape may not be obtained.

The crystal melting peak (melting point) and the crystal melting energy shown here are D measured by differential scanning calorimetry.
It is obtained from the SC curve and the measuring method is as follows.

Using a differential scanning calorimeter, the temperature was raised from −50 ° C. to 200 ° C. at a rate of 10 ° C./min, held for 5 minutes, and then 10 ° C./min from 200 ° C. to −50 ° C. After decreasing the temperature at a speed and holding for 5 minutes, -50 ℃ to 200 ℃
The melting point is the crystal melting peak temperature of the DSC curve obtained by the second temperature increase at a rate of 10 ° C./min. The energy per unit weight of the area surrounded by 25 to 100 ° C. occupying the energy per unit weight of the area surrounded by the baseline is defined as the crystal melting energy (Ea), 12
The energy per unit weight of the area surrounded by 0 ° C to the melting end temperature was calculated as the crystal melting energy (Eb).

The blending of the polyolefin resin (A) and the polyolefin resin (B) constituting the polyolefin resin composition having the foaming ability of the present invention is different from that of the foamed product obtained by heating the composition for the above-mentioned reason. Among the crystal melting energies per unit weight obtained from the crystal melting peak area of the DSC curve measured by scanning calorimetry, the crystal melting energy (Ea) at 100 ° C. or lower is 20 to 100 mJ /
It is necessary to adjust so that the crystal melting energy (Eb) at 120 ° C. or higher measured in the same manner is 10 to 150 mJ / mg.

The mixing ratio of the polyolefin-based resin (A) and the polyolefin-based resin (B) depends on the selected polyolefin-based resin. (A): 20-80% by weight (B): 20-80% by weight It is preferable that (A) is 30 to 60% by weight, and (B) is 40 to 70% by weight.

20% by weight of polyolefin resin (A)
If less than 80% by weight of the polyolefin-based resin (B), it is obtained from the crystal melting peak area of the DSC curve of the foamed product obtained by heat-processing the polyolefin-based resin composition having the foaming ability, which is measured by differential scanning calorimetry. Of the crystal melting energies per unit weight, when the crystal melting energy (Ea) at 100 ° C. or lower is less than 20 mJ / mg, or the crystal melting energy (Eb) at 120 ° C. or higher measured similarly exceeds 150 mJ / mg. Sometimes,
Since the temperature of the heat applied when the composition is melt-kneaded and the temperature rise due to heat generation due to shearing occur, the frequency of foaming to form bubble nuclei such as decomposition or expansion of the powdery foaming agent due to heat is significantly increased. A foam having a poor expansion ratio or having a good cell shape when the appearance of the composition is inferior or when the composition is heat-processed to form a foam, which impairs the basic properties of the foam such as cushioning and heat insulating properties. May not be obtained.

Further, the polyolefin resin (A) is 80
More than 20% by weight and the polyolefin resin (B) is 20
When the amount is less than 10% by weight, the crystal melting energy per unit weight obtained from the crystal melting peak area of the DSC curve measured by differential scanning calorimetry of a foam obtained by heat-processing a polyolefin resin composition having a foaming ability Of which 1
Crystal melting energy (Ea) below 100 ℃ is 100mJ
In some cases, the crystal melting energy (Eb) at 120 ° C. or higher measured in the same manner is less than 10 mJ / mg, and there is no foaming that forms a cell nucleus such as decomposition or expansion of the powdery foaming agent. It is possible to melt-knead the composition, but when the composition is heat-processed to form a foam, the heat resistance is remarkably lowered, which may be impractical.

The polyethylene resin used in the polyolefin resin composition having the foaming ability of the present invention is not particularly limited, but for example, a polyethylene resin having ethylene as a main chain or a copolymer thereof is exemplified. Vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-diene copolymer, ethylene-propylene-diene terpolymer, ethylene-octene copolymer, low density polyethylene, ethylene and carbon number 4 to Examples include linear polyethylene copolymerized with 12 α-olefins, high-density polyethylene, and thermoplastic elastomers having an ethylene-based resin as a hard segment, and each may be used alone or in combination of two or more kinds. The α-olefin copolymerized with ethylene is not particularly limited, but for example, propylene, 1-butene, 1-pentene, 3,3-dimethyl-
1-butene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1-decene, 1-dodecene, 1-
Tetradecene, 1-octadecene and the like are preferable. Among the polyethylene resins exemplified above, those having a melting point of 100 ° C. or lower are polyolefin resins (A), and those having a melting point higher than 100 ° C. are polyolefin resins (B).
It is preferable to use

The MFR measured at 190 ° C. is preferably 1 to 100 g / 10 minutes, and further 1
It is preferably -50 g / 10 minutes. MFR is 1g
If it is less than / 10 minutes, the temperature of the heat applied when melt-kneading the polyolefin resin having the foaming ability and the temperature rise due to the shear heat generation occur, and the bubble nuclei such as decomposition and expansion due to the heat of the powdery foaming agent are generated. When the composition is inferior in appearance because the frequency of foaming to be formed remarkably increases, or when the composition is heat-processed to form a foam, foaming that impairs basic foam properties such as cushioning properties and heat insulation properties. In some cases, it may not be possible to obtain a foam having a good expansion ratio or a bubble shape.
If it exceeds g / 10 minutes, it is possible to melt-knead without foaming to form cell nuclei such as decomposition and expansion of the foaming agent, but since the melt viscosity of the polyolefin resin is low, the composition is heat-processed to foam. When the body does not reach the expansion ratio that impairs the basic properties of the foam, such as cushioning and heat insulation,
Deformation due to heat may increase, resulting in poor heat resistance. The MFR shown here is measured by a measuring method according to JIS K-6922-2.

The polypropylene-based resin is not particularly limited, and examples thereof include a polyethylene-based resin having propylene as a main chain or a copolymer thereof, and polypropylene, propylene-based ethylene or α-olefin random resin. Alternatively, a block copolymer and a thermoplastic elastomer having a propylene-based resin as a hard segment are exemplified, and each can be used alone or in combination of two or more kinds. The type and number of α-olefin to be copolymerized with propylene are not particularly limited, but for example, ethylene, 1-butene, 1-pentene, 3,3-dimethyl-1-butene, 4-methyl-1.
-Pentene, 4,4-dimethyl-1-pentene, 1-decene, 1-dodecene, 1-tetradecene, 1-octadecene and the like are preferable.

The MFR measured at 230 ° C. is preferably 0.5 to 50 g / 10 minutes, more preferably 1 to 20 g / 10 minutes. If the MFR is less than 0.5 g / 10 minutes, the heat applied during the melt-kneading of the polyolefin-based resin composition having the foaming ability will rise and the temperature will rise due to the heat generated by shearing. Since the frequency of foaming such as decomposition and expansion to form cell nuclei is significantly increased, the appearance of the composition is inferior, or when the composition is heat-processed to form a foam, the foam has a cushioning property and a heat insulating property. In some cases, a foaming ratio that does not satisfy the basic characteristics may not be achieved, or a foam having a good cell shape may not be obtained. On the other hand, when it exceeds 50 g / 10 minutes, foaming that forms a cell nucleus such as decomposition or expansion of the foaming agent. Although it is possible to melt-knead the composition without foaming, foaming that impairs the basic properties of the foam such as cushioning and heat insulation when the composition is heat-processed to form a foam due to the low melt viscosity of the polyolefin resin. Unscaled And, in some cases deformed by heat is a heat-resistant poor increased. The MFR shown here is JIS K-6.
It is measured by the measuring method according to 921-2.

The powdery foaming agent used in the polyolefin resin composition having the foaming ability of the present invention has a temperature at which foaming such as decomposition and expansion due to heat starts (hereinafter referred to as foaming start temperature) from 100 to 180 ° C. And more preferably 120 to 160 ° C., more preferably a pyrolytic chemical blowing agent, a thermal expansion microcapsule, or a mixture thereof.

When the foaming starting temperature of the powdery foaming agent is less than 100 ° C., the frequency of foaming to form cell nuclei such as decomposition and expansion due to heat of the foaming agent when melt-kneading with the polyolefin resin is remarkable. If the appearance of the resin composition having foaming ability is poor, or if the composition is heat-processed to form a foam, a foaming ratio that does not meet the basic foam characteristics such as cushioning and heat insulating properties is not reached. In some cases, a foam having a good cell shape may not be obtained, and when the foaming start temperature of the foaming agent exceeds 180 ° C., the heat applied during foaming processing of the composition becomes high and the viscosity of the polyolefin resin decreases, resulting in foaming. It may be difficult to form and maintain the film, resulting in a low expansion ratio that does not satisfy the basic properties of the foam such as cushioning properties and heat insulation properties, or it may be economically impractical due to a delay in processing time.

The foaming onset temperature of the powdery foaming agent shown here is measured by the following method.

In the TG curve obtained when 10 mg of the powdery foaming agent sample was heated at a rate of 2 ° C./minute from 25 ° C. to 300 ° C. by using a thermogravimetric measuring device, 5 with respect to the reference sample weight. The temperature at which the weight% is reduced is defined as the foaming start temperature. In addition, a slight change may occur from the start of measurement due to the influence of water content, and the reference sample weight is 25 to 8
The average weight was 0 ° C.

The thermal decomposition type chemical foaming agent is not particularly limited as long as it is a chemical foaming agent that decomposes by releasing heat and releases gas, and for example, various types such as organic and inorganic types are available. Azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, P.I. Inorganic compounds such as P'-oxybenzenesulfonyl hydrazide include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate,
Calcium azide and the like are exemplified, and each can be used alone or in combination of two or more kinds.

The heat-expandable microcapsules are not particularly limited as long as the resin microspheres containing the low boiling point hydrocarbon expand by the application of heat, for example, ethane, propane, butane, pentane. , Hexane, low boiling point hydrocarbons such as heptane, polyvinylidene chloride, vinylidene chloride-acrylonitrile copolymer, polyacrylonitrile, acrylonitrile-methyl acrylate, etc. are included in the outer shell wall is exemplified, and each is alone. Alternatively, two or more kinds can be used in combination.

The thermal decomposition type chemical foaming agent and the thermal expansion type microcapsule can be used alone or in combination of two or more kinds.

The amount of the powdery foaming agent added is such that the foaming ratio of the foamed product obtained by heat processing is 5 times or more, more preferably 5 times.
It is preferable that the adjustment is made within a range of up to 30 times. If the expansion ratio is less than 5 times, the characteristics of the foam such as cushioning properties, heat insulation properties, and lightweight properties may be significantly impaired.
When the expansion ratio exceeds 30 times, compression recovery properties and compression set properties may be significantly impaired, and since a large amount of thermal expansion type microcapsules needs to be added, melt kneading with a polyolefin resin is required. In some cases, defects may occur, resulting in poor appearance or the desired expansion ratio.

The expansion ratio shown here is the reciprocal of the apparent density measured by a measuring method according to JIS K-6767 after a polyolefin resin composition having a foaming ability is heat-processed to form a foam.

Since the polyolefin resin composition having a foaming ability of the present invention contains the polyolefin resin (B) having a crystal melting peak (melting point Tmb) of more than 100 ° C., it is used for holding a foam film during the foaming process. It is possible to keep the melt viscosity high, and it is possible to obtain a processed foam in a finely crosslinked state which is superior in recyclability.

Further, in order to improve the appearance of the processed foam and increase the magnification, the melt viscosity of the resin may be increased by cross-linking within a range not impairing the recyclability. The degree of crosslinking at this time is 0 to
30% is preferable, and 0 to 20% is more preferable. When the degree of cross-linking exceeds 30%, a foamed structure including a foam obtained by heat-processing a polyolefin resin composition and other articles joined to the foam is melted poorly when heat is applied for recycling to perform various processes. Processing defects due to unmelted material,
Problems such as poor appearance may occur.

The cross-linking method is not particularly limited, but an electron beam cross-linking method of irradiating with ionizing radiation to cross-link, a chemical cross-linking method of kneading an organic peroxide to decompose and cross-link the organic peroxide during foaming, and a silane group are used. The silane cross-linking method is exemplified in which the polyolefin resin is mixed and brought into contact with water to cross-link, and these cross-linking methods can be used alone or in combination of two or more kinds. Various conditions such as energy for irradiation of ionizing radiation, amount of organic peroxide added, amount of silane group contained in resin, and contact condition of water are particularly preferable as long as the degree of crosslinking is in the range of 0 to 30%. It is not limited. The degree of crosslinking shown here is obtained by extracting 0.1 g of finely chopped foam in tetralin at 130 ° C., filtering it with a 100-mesh stainless steel wire net, and using the following formula from the extraction residual amount on the wire net. is there.

Crosslinking degree = [remaining amount of extraction / 0.1] × 100 (%) The polyolefin resin composition having the foaming ability of the present invention may be, for example, a heat stabilizer, a weather resistance agent, a flame retardant, a flame retardant agent, if necessary. Various known additives such as a combustion aid, a dispersant, a pigment, a fluidity improver, a release agent, a filler and a nucleating agent may be added.

The method for producing a polyolefin resin composition having the foaming ability of the present invention comprises mixing the polyolefin resin (A) and the polyolefin resin (B), a powdery foaming agent and various additives as required. A method of melt-kneading using a general-purpose kneading device such as an extruder or a mixing roll within a temperature range not lower than the melting point (Tma) of the polyolefin resin (A) and not higher than the foaming start temperature of the foaming agent. To be Further, a raw material prepared by kneading the polyolefin resin (A) and the polyolefin resin (B) in a molten state at a melting point (Tmb) of the polyolefin resin (B) or higher using a general-purpose kneading device such as an extruder or a mixing roll is prepared. Then, this is mixed with a powdery foaming agent, various additives as required, and the like, within a temperature range not lower than the melting point (Tma) of the polyolefin resin (A) and not higher than the foaming start temperature of the foaming agent. A method of melt-kneading using a general-purpose kneading device such as an extruder or a mixing roll can also be used. By such a method, it is possible to obtain a polyolefin resin composition having a foaming ability, which is formed into a long product such as a sheet or a strand.

The shape of the polyolefin-based resin composition is inserted in a predetermined space in a later step or bonded to another article, and in consideration of the workability in forming a heat-foamed foamed structure under such a condition, It is necessary to cut the composition into a plate shape, a chip shape, and a powder shape. When performing cross-linking treatment in advance, for example, when performing cross-linking before foaming such as electron beam cross-linking method or silane cross-linking method, after performing cross-linking treatment with a long object such as sheet or strand, single plate cutting machine It is cut into a plate, chip, or powder with a general-purpose cutting machine such as a pelletizer or a crusher. In addition, if no crosslinking treatment is required in advance, such as when not performing crosslinking treatment or when performing crosslinking during foaming as in the chemical crosslinking method, after molding into a long object such as a sheet or a strand. , Single plate cutting machine,
It is cut into a plate shape, chip shape, or powder shape with a general-purpose cutting machine such as a pelletizer or a crusher. A polyolefin resin composition having a foaming ability of the present invention, which is processed into a plate shape, a chip shape, or a powder shape by such a method, is produced.

[0039]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

The measuring methods and evaluation criteria in the present invention are as follows. 1. 40 m of a polyolefin resin composition having a kneadable foaming ability
When forming into a plate shape with an mφ single screw extruder, it is determined whether melt kneading is possible at a temperature at which the powdery foaming agent does not decompose.
The resin is softened and the foaming agent is melted and kneadable without being foamed such as decomposition or expansion due to temperature (pass),
Some defects are found, but those that can be processed into foam and do not impair the basic foam characteristics such as cushioning and heat insulation properties are passed (○), and the foam basic characteristics such as cushioning and heat insulation properties are affected significantly If there is foaming such as decomposition or expansion of the foaming agent, it is judged as unacceptable (x).

2. Foam appearance Visual evaluation is performed on the strain, surface flatness, and uniformity of foam of a foam obtained by heat-foaming a polyolefin resin composition having a foaming ability in the form of a plate, a chip, or a powder. Passed those with little yellow coloring due to the influence of undecomposed chemical foaming agent, with no distortion of foam, gas escape holes of foaming agent on the surface, unevenness due to unevenness of foaming, and maintaining uniform bubble shape (◎), somewhat Although there are some defects, those that do not impair the basic properties of the foam such as cushioning and heat insulation are passed (○), and those that have defects that impair the basic properties of foam such as cushioning and heat insulation are rejected ( X).

3. Foaming ratio Plate-like, chip-like, powder-like, and the apparent density of a foamed product obtained by heat-foaming a polyolefin resin composition having a foaming ability is measured by a measuring method according to JIS K-6767,
The reciprocal value of this apparent density is taken as the expansion ratio. Passed with a foaming ratio of 5 times or more in all shapes (○), 5
If less than double is included, it is judged as rejected (x).

4. Heat-resistant temperature plate-shaped, chip-shaped, powder-like foamed polyolefin resin composition having foaming ability
Cut out a 15 cm square sample, measure the thickness Z0 cm at its center, and measure 10 cm in length parallel to each side.
Draw the crossed lines, and put this sample in a hot air circulation oven, heat it for 22 hours, remove it, and let it cool naturally to room temperature. The thickness Z1 cm of this heat-treated sample and the lengths L1 and L2 cm of the vertical and horizontal marked lines are measured, and the heating volume change rate is calculated according to the following formula.

Heating volume change rate (%) = [{(10 × 10
XZ0)-(L1xL2xZ1)} / (10x10xZ
0)] × 100 (%) The heating volume change of each hot air temperature set at 10 ° C. intervals is measured, and the maximum temperature of ± 10% or less is set as the heat resistant temperature, and 100 ° C. or more, which is a temperature excellent in heat resistance, is set. Pass (○), 10
A temperature of less than 0 ° C is determined as a failure (x).

5. Comprehensive evaluation Composition kneadability, foam appearance, and heat resistance temperature are all judged to pass, and the overall evaluation is passed, and any one of composition kneadability, foam appearance, and heat resistance temperature is not acceptable. If there is a pass judgment, it is judged as a failure in the comprehensive evaluation.

Example 1 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 6
0 parts by weight, ethylene-propylene random copolymer (melting point 143 ° C., MFR as polyolefin-based resin (B)
2.0 g / 10 minutes) 40 parts by weight, "Ir
0.3 parts by weight of ganox 1010 ″ is melt-kneaded and pulverized in advance by a 40 mmφ single screw extruder set to 210 ° C. and azodicarbonamide (foaming start temperature 138 ° C.) as a powdery foaming agent 10 parts by weight Was mixed with a Henschel mixer and set to 110 ° C.
A plate sheet having a thickness of 2 mm was prepared by melt-kneading with a mmφ single screw extruder. This plate-shaped sheet was irradiated with 2 Mrad of an electron beam with an acceleration voltage of 800 kV to crosslink. This plate-like sheet was a polyolefin-based resin composition having good foaming ability, with no bubbles being recognized due to decomposition of the foaming agent. A processed foam obtained by foaming the plate-shaped composition in a hot air oven at 160 ° C., the composition obtained by cutting the plate-shaped sheet into chips of about 2 mm square, and a diameter of 2 with a crusher.
Each of the powdered compositions pulverized into a size of not more than mm was put in a mold having a thickness of 5 mm, and heat foamed by a press machine set at 160 ° C. to obtain three types of processed foams.
Kneadability of the composition, crystal melting energy of heat-processed foam at 100 ° C. or lower (Ea), crystal melting energy at 120 ° C. or higher (Eb), physical appearance of foam, expansion ratio, heat resistant temperature and other physical properties and evaluation results Is shown in Table 1. All the evaluation items passed.

Example 2 An electron beam with an accelerating voltage of 800 kV was irradiated with 0.5 Mrad,
A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the measured value of the degree of crosslinking was 0.3%. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. Depending on the shape of the composition, coarse bubbles were partially observed on the appearance, but all the evaluation items passed.

Example 3 An electron beam having an acceleration voltage of 800 kV was irradiated with 3.8 Mrad,
A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the measured value of the degree of crosslinking was 23.2%. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. Depending on the shape of the composition, coarse bubbles were partially observed on the appearance, but all the evaluation items passed.

Example 4 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 6
0 parts by weight, high density polyethylene as a polyolefin resin (B) (melting point 135 ° C., MFR 5.0 g / 10 minutes)
A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the amount was 40 parts by weight. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. All the evaluation items passed.

Example 5 As a polyolefin resin (A), 60 parts by weight of an ethylene-α-olefin copolymer (melting point 84 ° C., MFR 3.0 g / 10 minutes) using a metallocene compound as a polymerization catalyst, polyolefin resin (B) Ethylene-propylene random copolymer (melting point 143 ° C., MFR 2.0 g / 10
Min) A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the amount was 40 parts by weight. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. All the evaluation items passed.

Example 6 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 min) 6
0 part by weight, a thermoplastic elastomer (melting point 141 ° C., MFR 3.0) having a hard segment of ethylene-propylene random copolymer as the polyolefin resin (B).
g / 10 minutes) A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the amount was 40 parts by weight. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. All the evaluation items passed.

Example 7 It has the same foaming ability as in Example 1 except that 30 parts by weight of thermal expansion type microcapsules (foaming start temperature: 152 ° C.) as a powdery foaming agent and non-crosslinked without electron beam irradiation. A polyolefin resin composition and a processed foam thereof were obtained. Table 1 shows the physical properties of the composition and the heat-processed foam and the evaluation results. All the evaluation items passed.

Comparative Example 1 The procedure was repeated except that the polyolefin resin (B) was not added, and the polyolefin resin (A) was 100 parts by weight of an ethylene-vinyl acetate copolymer (melting point 76 ° C., MFR 4.0 g / 10 minutes). As in Example 1, a polyolefin resin composition having a foaming ability and a processed foam thereof were obtained. Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. Crystal melting energy (Eb) of heat-processed foam is 1
When it was less than 0 mJ / mg, the heat resistant temperature of the foam became less than 100 ° C. Therefore, the overall evaluation was unacceptable.

Comparative Example 2 The polyolefin resin (A) was not added, but a linear low-density polyethylene (melting point 1 was used as the polyolefin resin (B).
A polyolefin resin composition having a foaming ability was melt-kneaded in the same manner as in Example 1 except that 100 parts by weight of 22 ° C. and MFR of 8.0 g / 10 minutes) was used. The evaluation results of the composition are shown in Table 2. At the time of melt-kneading with a 40 mmφ single-screw extruder, it was difficult to melt-knead at 110 ° C., and when the temperature was raised to a kneadable melt state (150 ° C.), remarkable decomposition of the powdery foaming agent was observed. . Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. The decomposition of the powdered foamed material was remarkable, and the heat-processed foam was less than 5 times that did not satisfy the basic properties of the foam such as buffering property and heat insulating property. As a result, the overall evaluation was unacceptable.

Comparative Example 3 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 9
5 parts by weight, ethylene-propylene random copolymer as a polyolefin resin (B) (melting point 143 ° C., MFR
2.0 g / 10 minutes) A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the amount was 5 parts by weight. Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. With respect to the mixing ratio of the polyolefin resin, the crystal melting energy (Eb) of the heat-processed foam was less than 10 mJ / mg, and the heat resistant temperature of the foam was less than 100 ° C. Therefore, the overall evaluation was unacceptable.

Comparative Example 4 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 9
5 parts by weight, high-density polyethylene (melting point 135 ° C., MFR 5.0 g / 10 minutes) as polyolefin resin (B)
A polyolefin resin composition having a foaming ability and a processed foam thereof were obtained in the same manner as in Example 1 except that the amount was 5 parts by weight. Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. With respect to the mixing ratio of the polyolefin resin, the heat melting foam has a crystal melting energy (Eb) of less than 10 mJ / mg and the foam has a heat resistant temperature of 100 ° C.
Was less than. Therefore, the overall evaluation was unacceptable.

Comparative Example 5 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 1
0 parts by weight, ethylene-propylene random copolymer (melting point 143 ° C., MFR as polyolefin-based resin (B)
(2.0 g / 10 min) 90 parts by weight except that the polyolefin resin composition having a foaming ability was melt-kneaded in the same manner as in Example 1. The evaluation results of the composition are shown in Table 2.
During melt-kneading with a 40 mmφ single-screw extruder, it was difficult to melt-knead at 110 ° C., and when the temperature reached to a kneadable melt state (160 ° C.), remarkable decomposition of the powdery foaming agent was observed. . Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. With the mixing ratio of the above polyolefin resin, the crystal melting energy (Ea) of the heat-processed foam is less than 20 mJ / mg, and it is necessary to raise the temperature for kneading the composition. The decomposition was remarkable, and the heat-processed foam was less than 5 times which did not satisfy the basic foam characteristics such as cushioning property and heat insulating property. As a result, the overall evaluation was unacceptable.

Comparative Example 6 As a polyolefin resin (A), an ethylene-vinyl acetate copolymer (melting point: 76 ° C., MFR: 4.0 g / 10 minutes) 1
0 parts by weight, high density polyethylene as a polyolefin resin (B) (melting point 135 ° C., MFR 5.0 g / 10 minutes)
A polyolefin resin composition having a foaming ability was melt-kneaded in the same manner as in Example 1 except that the amount was 90 parts by weight.
The evaluation results of the composition are shown in Table 2. During melt-kneading with a 40 mmφ single-screw extruder, it was difficult to melt-knead at 110 ° C., and when the temperature reached to a kneadable melt state (160 ° C.), remarkable decomposition of the powdery foaming agent was observed. .
Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. At the mixing ratio of the above polyolefin resin, the crystal melting energy (Ea) of the heat-processed foam is 2
Less than 0 mJ / mg, crystal melting energy (Eb) is 15
It exceeds 0 mJ / mg, and the temperature for kneading the composition needs to be high. Therefore, the decomposition of the powdery foaming agent is remarkable during the kneading, and the heat-processed foam has a foaming property such as buffering property or heat insulating property. It was less than 5 times that does not satisfy the basic characteristics. As a result, the overall evaluation was unacceptable.

Comparative Example 7 The same foaming ability as in Example 1 except that 30 parts by weight of thermal expansion type microcapsules (foaming start temperature 83 ° C.) as a powdery foaming agent and non-crosslinked without electron beam irradiation were used. The polyolefin resin composition was melt-kneaded. The evaluation results of the composition are shown in Table 2. During the melt-kneading with a 40 mmφ single screw extruder, remarkable expansion of the foaming agent was observed. Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results.
Shown in. The decomposition of the powdery foaming agent was remarkable, and the heat-processed foam was less than 5 times which did not satisfy the basic foam characteristics such as buffering property and heat insulating property. As a result, the overall evaluation was unacceptable.

Comparative Example 8 A polyolefin resin composition having the same foaming ability as in Example 1 except that 10 parts by weight of azodicarbonamide (foaming start temperature 191 ° C.) as a powdery foaming agent and a foaming processing temperature of 240 ° C. were used. Was melt-kneaded. Similarly, a polyolefin resin composition having a foaming ability and a processed foam thereof were obtained. Table 2 shows the physical properties of the composition and the heat-processed foam and the evaluation results. The obtained processed foam has an expansion ratio of 5 which does not satisfy the basic properties of the foam such as cushioning and heat insulation due to the escape of the decomposition gas of the foaming agent due to insufficient resin melt viscosity.
It was less than twice. As a result, the overall evaluation was unacceptable.

As described above, the resin composition according to the present invention shown in the examples comprises at least two polyolefin resins having specific melting points and a powdery foaming agent having a specific foaming initiation temperature by heat. In a resin composition of a specific shape obtained by melt-kneading, the foam processed by heating the composition is inserted into a predetermined space having a specific crystal melting energy,
A polyolefin-based resin composition that has the foaming ability of being joined to another article and heat-foamed under such a state to have a foaming ability, and particularly has excellent processability and heat resistance, and has recyclability by remelting processing. is there.

The following Tables 1 and 2 summarize the above Examples and Comparative Examples.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

According to the resin composition of the present invention, heat resistance,
A polyolefin resin composition having properties such as recyclability and foaming ability can be obtained. Further, according to the production method of the present invention, the resin composition is inserted into a predetermined space or joined to another article, and heat-foamed under various processes to form a foamed structure, and various processes involving heating. On the other hand, it is possible to easily obtain a polyolefin resin composition having a foaming ability capable of selecting a foamed structure having a high degree of freedom and a processing method.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Futoshi Sasamoto             1-1 1-1 Sonoyama, Otsu City, Shiga Prefecture Toray Co., Ltd.             Ceremony company Shiga business site (72) Inventor Mihoko Makino             1-1 1-1 Sonoyama, Otsu City, Shiga Prefecture Toray Co., Ltd.             Ceremony company Shiga business site (72) Inventor Toshiyuki Kobayashi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F term (reference) 4F071 AA15 AA15X AA20 AA20X                       AA28X AA80 AA87 AC02                       AC12 AC13 AD02 AD04 AE01                       BA01 BB06 BC01                 4J002 BB03W BB05W BB06W BB07W                       BB10W BB11X BB12X BB15W                       BB15X BF03W DE226 DF006                       EA026 EN046 EQ016 EV346                       FA106 FD326

Claims (6)

[Claims] 1. A resin composition mainly composed of a polyolefin-based resin having a foaming ability, which is inserted into a predetermined space or bonded to another article to form a foamed structure which is heat-foamed under such a condition, Foaming start temperature due to heat is 100-1
It contains a powdery foaming agent at 80 ° C and its shape is plate-like,
Polyolefin resin (A) having a crystal melting peak (melting point Tma) of 100 ° C. or less, and crystals exceeding 100 ° C., which are in the form of chips, powder, or a mixture thereof. From a crystal melting peak area of a DSC curve of a foamed product which is composed of at least two kinds of resins including a polyolefin resin (B) having a melting peak (melting point Tmb) and which is subjected to heat processing of the composition, by a differential scanning calorimetry analysis. Of the crystal melting energies per unit weight obtained, the crystal melting energy (Ea) at 100 ° C. or lower is 20 to 100 mJ / mg, and
Crystal melting energy (Eb) above 120 ° C is 10-1
A polyolefin resin composition having a foaming ability, which is 50 mJ / mg. 2. The polyolefin resin composition having a foaming ability according to claim 1, wherein the polyolefin resin (A) is a polyethylene resin. 3. The polyolefin resin composition having a foaming ability according to claim 1, wherein the polyolefin resin (B) is a polyethylene resin, a polypropylene resin or a mixture thereof. 4. The powdery foaming agent is a pyrolytic chemical foaming agent,
The polyolefin resin composition having a foaming ability according to any one of claims 1 to 3, which is a thermal expansion type microcapsule or a mixture thereof. 5. The degree of crosslinking of the heat-processed foam is 0 to 3
The polyolefin resin composition having a foaming ability according to any one of claims 1 to 4, which is in the range of 0%. 6. The polyolefin resin (A) and the polyolefin resin (B) according to any one of claims 1 to 5.
And a powdery foaming agent at a crystal melting peak (melting point Tma) of the polyolefin-based resin (A) or more and less than the foaming start temperature due to heat of the foaming agent, the resin composition is subjected to a post-process. 1. A method for producing a polyolefin resin composition having a foaming ability, which is characterized in that it is formed into a plate shape, a chip shape, or a powder shape.