KR100619287B1 - Compositions for high -magnifying foam and light-weight foams produced by them - Google Patents

Abstract

According to the present invention, a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt is added in an amount of 5 to 50 parts by weight, 3 to 20 parts by weight of a blowing agent, and 0.05 to 2 parts by weight of a crosslinking agent based on 100 parts by weight of an ethylene-vinylacetate copolymer. 5 to 50 parts by weight of a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt with respect to 100 parts by weight of an ethylene-vinylacetate copolymer formed, 5 to 70 parts by weight of a polyolefin elastomer, and a foaming agent to 3 to 20 It relates to a foam composition and a foam using the same, characterized in that the addition by weight, 0.05 to 2 parts by weight of the crosslinking agent, the foam according to the present invention while achieving a lightweight by high magnification foam and at the same time excellent mechanical properties shoe sole, It is usefully used for interior and exterior building materials, automobile parts, and packaging materials.

Ethylene-vinylacetate, carboxylic acid group, higher fatty acid metal salt, high magnification foam, light weight

Description

Compositions for high-magnification foams and light-weight foams using the same

The present invention relates to a foam composition and a foam using the same for achieving super-lightweight by high magnification foam and at the same time excellent in mechanical properties.

Synthetic resin foams that are useful for footwear parts (sponge, midsole, outsole, etc.), interior and exterior materials, door glass runs, interior parts, and packaging materials include polyethylene, polypropylene, ethylene-vinylacetate copolymer, polyester, It is made of various materials such as polyurethane. Among them, foams based on ethylene-vinylacetate copolymers are usually manufactured by various processing methods such as press foam molding and injection foam molding, and are widely used as shoes parts because of their advantages of being light, discolored and inexpensive.

One of the urgent demands for such foams is the manufacturing technology of foams with excellent mechanical properties despite the fact that they are foamed at a magnification of more than six times higher without deteriorating existing mechanical properties and so-called extremely light weights of which the specific gravity falls below 0.15. .

That is, crosslinked foams utilizing a composition for foams composed of a conventional ethylene-vinylacetate copolymer, a foaming agent such as azodicarbonamide, a crosslinking agent such as an organic peroxide, and the like are usually less than 6 times in the case of commercially available products. The specific gravity due to the expansion ratio of is maintained at a level of 0.18 to 0.20, but if a high magnification foaming intentionally, mechanical properties such as compressive permanent shrinkage, impact absorption rate has been significantly reduced. Accordingly, Japanese Patent Application Laid-Open No. 11-206406 and Korean Patent Registration No. 2004-456392 disclose a mixture of ethylene-vinylacetate copolymer and ethylene-α-olefin copolymer, ethylene-vinylacetate copolymer, ethylene-α-olefin air Cross-linked foams using a composition for foams based on coalescing and mixtures with high-density low-density polyethylene and the like have been attempted to improve the conventional problems, but this also has not obtained sufficient performance.

That is, the emergence of ultra-light foam based on the ethylene-vinylacetate copolymer having a specific gravity of 0.15 or less by 6 times or more high magnification foaming is excellent.

MEANS TO SOLVE THE PROBLEM In order to solve the said problem, the present inventors earnestly studied and came to this invention.

That is, the present invention is to provide a novel ethylene-vinylacetate copolymer system composition and foam having excellent mechanical properties as an ultra-light foam having a specific gravity of 0.15 or less obtained by 6 times or more high magnification foaming.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, 5-50 weight part of mixtures of a carboxylic acid group containing polyethylene-type copolymer and a higher fatty acid metal salt with respect to 100 weight part of ethylene-vinylacetate copolymers, 3-20 weight part of foaming agents, a crosslinking agent It is providing the composition for foams which is added and formed in 0.05-2 weight part.

The present invention also relates to 5 to 50 parts by weight of a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt, 5 to 70 parts by weight of a polyolefin elastomer, and 3 to 20 parts by weight of an ethylene-vinylacetate copolymer. It is providing the composition for foams which is added and formed by 0.05-2 weight part of crosslinking agents.

The ethylene-vinylacetate copolymer in the present invention is obtained by copolymerizing ethylene and vinyl acetate, and the vinyl acetate content is preferably in the range of 10 to 30% by weight, more preferably in the range of 15 to 25% by weight, and is further melted. The index (190 ° C, load 2.16Kg) is preferably 0.1 to 50 g / 10 minutes, and more preferably 0.5 to 20 g / 10 minutes. More specifically, the examples include DuPont's Elvax 462, 360, Samsung Total's E180F, and E210F. Etc. can be mentioned.

The carboxylic acid group-containing polyethylene copolymer in the present invention specifically means methacrylic acid or acrylic acid-containing polyethylene copolymer, and for example, methacrylic acid-ethylene copolymer, acrylic acid-ethylene copolymer, and methacrylic acid-methyl Methacrylate-ethylene copolymer, acrylic acid-methylacrylate-ethylene copolymer, methacrylic acid-methacrylic acid metal salt-ethylene copolymer, acrylic acid-acrylic acid metal salt-ethylene copolymer and the like. The methacrylic acid or acrylic acid content in the copolymer is preferably in the range of 3 to 20% by weight, more preferably in the range of 5 to 15% by weight. When the methacrylic acid or acrylic acid content is less than 3% by weight, it is difficult to obtain a high magnification foam having excellent desired mechanical properties, and when it exceeds 20% by weight, the composition for foams such as kneader, banbury, roll mill, etc. There is a fear that a problem of sticking to the mechanical metal surface during the manufacturing process may occur. The carboxylic acid group-containing polyethylene copolymer has a melt index (190 DEG C, a load of 2.16 Kg) of 0.5 to 50 g / 10 minutes, more preferably 1.0 to 15 g / 10 minutes, and a melt index of 0.5 g / 10 minutes. If less than the composition composition workability and processability of the foam is poor, if it exceeds 50g / 10 minutes there is a fear that the mechanical strength of the foam is weak. More specific examples of such carboxylic acid group-containing polyethylene copolymers include DuPont Nucrel 0403, a methacrylic acid-ethylene copolymer, ExxonMobil Escor 6000, an acrylic acid-ethylene copolymer, and ExxonMobil, Escor AT310, an acrylic acid-methyl acrylate-ethylene copolymer. Etc. can be mentioned.

The higher fatty acid metal salts of the present invention include higher fatty acids such as stearic acid, oleic acid, lauric acid, capric acid, palmitic acid and ricinolic acid, and alkali metals such as lithium, sodium, potassium, calcium, magnesium, and barium having 5 to 22 carbon atoms. Examples of the salt formed by at least one metal selected from transition metals such as alkaline earth metals, zinc, cobalt, copper, and iron include concretely potassium laurate, barium stearate, zinc stearate, and the like. Used alone or in combination.

In the present invention, the core of the technology introduced to obtain an ultra-light foam having a specific gravity of 0.15 or less by 6 times or more high magnification foam while maintaining excellent mechanical properties is maximized the melt tension during melt molding foaming of the composition to make it more uniform and more fine foaming. In order to cause the cell structure to express excellent mechanical properties, a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt is newly added to a foam composition composed of an ethylene-vinylacetate copolymer, a blowing agent, a crosslinking agent, and the like. The composition containing the appropriate amount is used.

First, a suitable amount of a carboxylic acid group-containing polyethylene copolymer was newly contained in a foam composition composed of a conventional ethylene-vinylacetate copolymer, a foaming agent, a crosslinking agent and the like. As a result, it showed an amazing increase in melt tension, and even more than 6 times high foaming, it showed uniform and more fine foamed cell structure and excellent mechanical properties, which means that the carboxylic acid group-containing polyethylene copolymer was ethylene-vinylacetate air. It is due to the fact that it has a similar structural and structural similarity, and it is also due to the fact that it expresses a kind of three-dimensional similar network structure by the strong hydrogen bonding power of the carboxylic acid groups present in the molecule, which causes an amazing increase in melt tension. do. Unfortunately, however, these carboxylic acid groups also exhibit strong bonding strength with metal surfaces of machines such as kneader, bamboo, roll mill, etc. in the preparation of the composition, and thus have encountered a great difficulty in sticking the lumps of the resin composition.

Introduced as a means to solve this difficulty is the addition of a higher fatty acid metal salt in addition to the novel carboxylic acid group-containing polyethylene copolymer in the foam composition composed of conventional ethylene-vinylacetate copolymer, foaming agent, crosslinking agent and the like. . According to this method, the sticky sticking operation is completely eliminated, and the melt tension is much higher than when only the carboxylic acid group-containing polyethylene copolymer is added. The result is a breakthrough that is smaller in size, more uniform and has excellent mechanical properties. This is because some of the higher molecular weight metal salts with low molecular weight are easily moved to the surface of the resin composition mass when kneading, which acts as a kind of heat-resistant lubricant to the metal surface of the machine such as kneader, bamboo, roll mill, etc. It is inferred to completely solve the great difficulty, and also some of these higher fatty acid metal salts present in the resin composition mass react with the carboxylic acid groups present in the carboxylic acid group-containing polyethylene-based copolymer to form a new metal salt form, eventually forming a collection of ions. By forming a typical structure of ionomer with a three-dimensional pseudo-network structure as a kind of crosslinking point, it is inferred that excellent mechanical properties can be secured by expressing many fine foam cells at high foaming with a breakthrough increase in melt tension. do.

It is preferable to add 5-50 weight part of mixtures of the said carboxylic acid group containing polyethylene type copolymer and a higher fatty acid metal salt with respect to 100 weight part of ethylene-vinylacetate copolymers, and it is more preferable to add 10-30 weight part. If the amount is less than 5 parts by weight, it is not possible to secure the weight reduction and mechanical properties due to the desired high foaming, and if it is added more than 50 parts by weight, the hardness may increase too much. The composition of the mixture of the carboxylic acid group-containing polyethylene copolymer and the higher fatty acid metal salt is preferably 70 to 95% by weight of the carboxylic acid group-containing polyethylene copolymer and 5 to 30% by weight of the higher fatty acid metal salt. When the content of the higher fatty acid metal salt is less than 5% by weight, there may be a sticky phenomenon on the metal surface of the machine such as kneader, bamboo, roll mill, etc., and if it exceeds 30% by weight, the mechanical strength may be reduced.

In addition, the addition of a new carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt to a foam composition composed of an ethylene-vinylacetate copolymer, a foaming agent, a crosslinking agent, and the like and a polyolefin-based elastomer further improves weight reduction and mechanical properties. The polyolefin-based elastomer according to the present invention is ethylene produced by a catalyst such as titanium, vanadium, metalocene, and the like having 3 to 20 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, etc. the density of 0.85 ~ 0.92g / cm ^3, a melt index of the copolymer of the α- olefin (190 ℃, 2.16Kg load) from 0.1 to as elastomer of 50g / 10 min, aiming for weight and improved mechanical properties, the purpose of the present invention More preferred is a polyolefin-based elastomer prepared by a metalocene catalyst having a lower density than the ethylene-vinylacetate copolymer and excellent mechanical properties. As a specific example, ExxonMobil is an ethylene-hexene copolymer elastomer having a density of 0.883 g / cm ³ . Exact 4056, Dow Chemical Co. Engage 8107 which is an ethylene-octene copolymer type elastomer of density 0.870g / cm <^3> , etc. are mentioned.

It is preferable to add 5-70 weight part of said polyolefin elastomer with respect to 100 weight part of ethylene-vinylacetate copolymers, and it is more preferable to add 10-40 weight part. If it is added less than 5 parts by weight, it is difficult to expect additional weight reduction and mechanical properties, and if it is added more than 70 parts by weight, the adhesion with other sponges, for example, a polyurethane-based adhesive, may be deteriorated and the ethylene-vinylacetate copolymer The more expensive, the worse the economics.

Examples of the blowing agent in the present invention include azo compounds such as azodicarbonamide, nitroso compounds such as N, N'-dinitrosopentamethylenetetramine, azobisisobutyronitrile, p-toluenesulfonylhydrazine, p, Known blowing agents such as p'-oxybis (benzenesulfonylhydrazide) and diazoaminoazobenzene may be mentioned, and 3 to 20 weight parts based on 100 parts by weight of the ethylene-vinylacetate copolymer in consideration of the foaming ratio and density of the foam. It is good to use vice. If the foaming agent content is less than 3 parts by weight, the resulting foam has a high hardness and high specific gravity. If it exceeds 20 parts by weight, the foam may be torn or form an unstable foam cell.

The crosslinking agent in the present invention is an organic peroxide, such as disilyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl- 2,5-di- (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, etc. are mentioned, Ethylene-vinylacetate air | atmosphere is mentioned. It is preferable to use 0.05-2 weight part with respect to 100 weight part of coalescence.

Although not a basic component of the composition of the present invention, if necessary, various additives such as white enhancer, dye, pigment, decomposition accelerator, heat stabilizer, weather stabilizer, and inorganic filler may be blended in a range that does not impair the object of the present invention.

Hereinafter, the composition and the method for preparing the foam according to the present invention will be described in more detail.

First, an ethylene-vinylacetate copolymer, a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt, a polyolefin elastomer, a crosslinking agent, a foaming agent, and the like are weighed into kneaders such as kneader, bamboo, roll mill, and the like. The mixture is sufficiently kneaded at a temperature below the decomposition point of (usually 90 to 110 ° C) to prepare a foamed composition in the sheet state. As a method for foaming the sheet-like foam, a press foam molding method, an injection foam molding method, or the like is used. According to the press-foaming method, first, the composition for sheet-like foam is introduced into a mold, and then processed using a press machine for a predetermined time (about 20 to 30 minutes) under high temperature pressure to decompose the crosslinking agent and the foaming agent, and then open the mold momentarily to reduce the pressure. By removing, a primary foam having a soft independent bubble structure is obtained through a primary press process of expanding rapidly using a pressure difference. This is turned into a certain size and thickness using a skiving machine and a cutter, and after trimming and grinding, it is put back into a mold having a desired product shape (about 5 ~ 20 minutes) and press at high temperature (about 150 ~ 160 ℃). With the mold closed again, it is cooled at a low temperature (about 10-20 ℃) for a certain time (10-20 minutes) to obtain a foam product of a desired form through a repressing process of demolding the product. In addition, according to the injection foam molding method, the composition for sheet-like foam is first made into a ribbon or pellet having a constant thickness and width by using a cutter, a crusher, or the like, and then injected into an injection molding machine. It is injected into the mold through the screw of the injection machine, and according to the decomposition temperature of the crosslinking agent and the blowing agent, the temperature inside the screw is adjusted to 80 ~ 120 ℃ and the mold temperature is set to 150 ~ 200 ℃, and the mold pressure is 150 ~ 400kg / cm ² . After 10 minutes of processing, the mold is opened instantaneously to demould and simultaneously foam to obtain the desired foam product.

As described above, the foam composition according to the present invention is a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt, or carboxyl, in a foam composition composed of an ethylene-vinylacetate copolymer, a foaming agent, a crosslinking agent, and the like. A mixture of an acid group-containing polyethylene copolymer with a higher fatty acid metal salt and an appropriate amount of a polyolefin elastomer are included, and the same action as a heat-resistant lubricant of the higher fatty acid metal salt causes stickiness to kneader, bamboo, roll mill, etc. The difficulty is completely solved, and also by forming a typical structure of the inomer having a three-dimensional pseudo network structure by reaction of such a higher fatty acid metal salt with a carboxylic acid group, and under a high foaming condition more than six times with a dramatic increase in melt tension Even but a lot of beauty By expressing the foam cell, it is a breakthrough to secure an ultra-light foam having a specific gravity of 0.15 or less, which has excellent mechanical properties.The foam thus obtained is used for automobile parts such as shoe parts (midsole, outsole, sponge), building interior and exterior materials, door glass run, interior materials, etc. It can be usefully used for parts, packaging materials and the like. In particular, the preference of light shoes, which are less burdensome to the running shoes, such as midsole, outsole made of ultra-light foam according to the present invention may be the most preferable solution.

Through the following examples will be described in more detail the present invention. The following examples are merely examples and are not limited to the examples.

Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the foams prepared according to the following Examples and Comparative Examples were measured as follows.

(importance)

The specific gravity of the foam was measured five times using an automatic specific gravity measurement apparatus after removing the surface and the average value was taken.

(Hardness)

Hardness was measured in accordance with ASTM D2240 by cutting an intermediate portion of the foam and an Asker C type hardness meter.

(Tensile strength and elongation)

The surface layer of the foam was removed, the thickness was 3mm, and the test piece was made with a cutter, and tensile strength and elongation were measured according to ASTM D412. At this time, five test pieces were used for the same test, and the tensile speed was 500 mm / min.

(Tear strength)

The tear test was performed in accordance with ASTM D3574 and ASTM D634, respectively, and the measurement speed was measured five times at 100 mm / min and the average value was taken.

Permanent compression rate

The test piece prepared in the form of a cylinder having a diameter of 30 + 0.05 mm by turning the foam up to 10 mm in thickness was measured according to ASTM D3547. Place the specimen between two parallel metal plates, insert a spacer equal to 50% of the specimen thickness, compress it, heat it in an air-circulating oven maintained at 50 + 0.1 ° C for 6 hours, and remove the specimen from the compression device. After cooling for 30 minutes at room temperature the thickness was measured. Three test pieces were used in the same test, and a compression set was calculated by the following equation (1).

Cs (%) = [(t ₀ -t _f ) / (t ₀ -t _s )] x100 .............. Equation (1)

Where Cs is the compressive permanent shrinkage, t ₀ is the initial thickness of the test piece, t _f is the thickness of the test piece when cooled after heat treatment, and t _s is the thickness of the spacer.

(Shock absorption rate)

The impact absorption rate was evaluated by evaluating the height of the rebound by freely dropping 35 g of metal spheres on the foam surface.

Example 1

Melt index of 1.5g / 10 bun (190 ℃, 2.16kg), and ethylene vinyl acetate containing 21% by weight of the density 0.870g / cm ³ - with respect to 100 parts by weight of vinyl acetate copolymer, melt index 2.5g / 10 min, a density 10 parts by weight of methacrylic acid-ethylene copolymer containing 9% by weight of methacrylic acid of 0.930 g / cm ³ and zinc stearate were weighed and kneaded at kneader for 10 minutes, followed by kneading at 105 ° C. for 10 minutes. 0.45 parts by weight of disilyl peroxide as a crosslinking agent and 3.5 parts by weight of azodicarbonamide as a blowing agent were added to prepare a foamed composition in the sheet state. After putting the obtained composition for sheet-like foams into a metal mold | die, it processed at 155 degreeC and 150 kg / cm <^{2> for} 20 minutes using the press machine, and obtained the primary foam. Turn it on to a certain size and thickness, and after trimming and grinding process, put it in the mold again and press hot at 155 ℃ for 10 minutes. The mold was closed again and cooled at 10 ° C. for 20 minutes and demolded to obtain a final foam specimen. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

Example 2

Except for changing the content of methacrylic acid-ethylene copolymer 20 parts by weight, the content of zinc stearate to 2 parts by weight of the components of Example 1 was carried out in the same manner as in Example 1. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

Example 3

Except for changing the content of methacrylic acid-ethylene copolymer of the component of Example 1 30 parts by weight, the content of zinc stearate to 3 parts by weight was carried out in the same manner as in Example 1. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

Example 4

20 parts by weight of a methacrylic acid-ethylene copolymer containing 9% by weight of methacrylic acid having a melt index of 2.5 g / 10 minutes, a density of 0.930 g / cm ³ , and 2 parts by weight of zinc stearate, based on 100 parts by weight of the ethylene-vinylacetate copolymer. Example 1, except that 20 parts by weight of an ethylene-octene copolymer elastomer having a melt index of 3.0 g / 10 minutes, a density of 0.882 g / cm ³ , 0.55 part by weight of a diglyme peroxide as a crosslinking agent, and 5.5 parts by weight of azodicarbonamide as a blowing agent. Foam specimens were obtained in the same manner as in the following. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

Example 5

Melt index of 2.0g / 10 min, a density containing 25 wt% vinyl acetate of 0.950g / cm ³ Ethylene-vinyl acetate copolymer based on 100 parts by weight, melt index 2.5g / 10 min, a density of 8.5 acrylic acid 0.936g / cm ³ 25 parts by weight of the acrylic acid-ethylene copolymer, 3 parts by weight of zinc stearate, and 30 parts by weight of an ethylene-octene copolymer elastomer having a density of 0.882 g / cm ³ were weighed into a kneader and kneaded at 95 ° C. for about 20 minutes. In a roll mill having a surface temperature of 100 ° C., 0.7 parts by weight of a disilyl peroxide as a crosslinking agent and 6.0 parts by weight of azodicarbonamide as a blowing agent were added to prepare a foamed composition in a sheet state. The obtained sheet-like foam composition was made into a ribbon-like sheet or pellet having a width of 30 mm and a thickness of about 2 mm, and then introduced into an injection molding machine. The temperature inside the screw was adjusted to 80 to 120 ° C. and the mold temperature was adjusted to 170 ° C. The foam specimen was obtained by processing at 250 kg / cm ² for 7 minutes and foaming simultaneously with demolding. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

[Comparative Example]

9% by weight of methacrylic acid-containing methacrylic acid-ethylene copolymer (DuPont Nucrel 0903) and zinc stearate (Songwon Industry) without prescribing at all based on 100 parts by weight of ethylene-vinylacetate copolymer (DuPont Elvax 462) A foam specimen was obtained in the same manner as in Example 1 except that 0.45 parts by weight of phosphorus disilyl peroxide and 5.5 parts by weight of azodicarbonamide (Gumyang Cellocom JTR / M) as a blowing agent were prescribed. Specific gravity, hardness, tensile strength, elongation, tear strength, compressive permanent shrinkage, and impact absorption for the obtained foam specimens were measured and the results are shown in Table 1.

TABLE 1 Foam evaluation results obtained according to Examples 1 to 5 and Comparative Examples

Normally, tensile strength, tear strength, impact absorption rate, and the like, and the compressive permanent shrinkage is smaller, the mechanical properties of the foam can be seen as excellent, as can be seen in Examples 1 to 3, meta-carboxylic acid-containing polyethylene copolymer Hardness and compressive permanent shrinkage tend to increase as the mixture content of acrylate-ethylene copolymer with zinc stearate, a higher fatty acid metal salt, increases, and it is known that it has very good mechanical properties despite being a low specific gravity foam. In Examples 4 and 5, when the ethylene-octene copolymer-based elastomer, which is a polyolefin-based elastomer, is additionally prescribed, the mechanical properties may be improved even though the specific gravity is very low. On the other hand, when looking at the comparative example it can be seen that the mechanical properties are very poor at low specific gravity. As a result, a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt or a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt is newly added to a foam composition comprising a conventional ethylene-vinylacetate copolymer, a foaming agent, a crosslinking agent, and the like. By containing an appropriate amount of polyolefin-based elastomers and polyolefin-based elastomers, a uniform and many fine foamed cells are produced under extremely high foaming conditions with a dramatic increase in melt tension due to the interaction of higher fatty acid metal salts and carboxylic acid groups in the carboxylic acid group-containing polyethylene copolymer. By expressing it can be seen that it possesses excellent mechanical properties despite being an ultralight foam having a specific gravity of 0.15 or less.

Claims (14)

5 to 50 parts by weight of a mixture of a carboxylic acid group-containing polyethylene copolymer and a higher fatty acid metal salt having 5 to 22 carbon atoms, 3 to 20 parts by weight of a blowing agent, and 0.05 to 2 parts by weight of a crosslinking agent based on 100 parts by weight of the ethylene-vinylacetate copolymer. Part and a copolymer of ethylene and an α-olefin having 6 to 20 carbon atoms, density 0.85 to 0.92 g / cm ³ , melt index (190 ° C., 2.16 Kg) 0.1 to 50 g / 10 minutes polyolefin elastomer 5 to 70 weight The foam composition, characterized in that the addition is formed by part. delete delete The method of claim 1, The carboxylic acid group-containing polyethylene copolymer is a foam composition, characterized in that the melt index (190 ℃, 2.16Kg) is methacrylic acid or acrylic acid-containing polyethylene copolymer of 0.5 to 50g / 10 minutes. The method of claim 4, wherein The carboxylic acid group-containing polyethylene copolymer is a copolymer of ethylene with at least one monomer selected from methacrylic acid, acrylic acid, methyl methacrylate, methyl acrylate, metal methacrylate salt and metal acrylate salt. The composition for the foam, characterized in that 3 to 20% by weight of one or more components selected from acrylic acid or methacrylic acid in the total monomers. The method of claim 1, The higher fatty acid metal salt is a foam composition, characterized in that any one or more metal salts selected from alkali metal, alkaline earth metal or transition metal salt of higher fatty acids having 5 to 22 carbon atoms. The method of claim 1, The mixture of the carboxylic acid group-containing polyethylene copolymer and the higher fatty acid metal salt is composed of 70 to 95% by weight of the carboxylic acid group-containing polyethylene copolymer and 5 to 30% by weight of the higher fatty acid metal salt. The foam composition according to any one of claims 1 and 4 to 7 is weighed and introduced into a kneader such as kneader, bamboo, roll mill, and kneaded at a temperature below the decomposition point of the crosslinking agent and the foaming agent to form a sheet-like foam composition. Obtaining; Injecting the sheet-like foam composition into a mold to obtain a primary foam under high pressure using a press; Manufacturing the foam by processing the primary foam in a predetermined form and then pressing molding again; Method for producing a foam comprising a. The method of claim 8, The primary foam is manufactured by rapidly expanding the mold after processing under high temperature and high pressure, turning it into a certain size and thickness using a skybing machine and a cutter, and then trimming and grinding the process, and then putting the mold back into the mold and pressing it again. Next, the foam is produced by cooling with the mold closed and demolding to produce a foam. The foam composition according to any one of claims 1 and 4 to 7 is weighed and introduced into a kneader such as kneader, bamboo, roll mill, and kneaded at a temperature below the decomposition point of the crosslinking agent and the foaming agent to form a sheet-like foam composition. Obtaining; Preparing the sheet-like foam composition in the form of a ribbon or pellets; Preparing the foam by injecting the composition into an injection molding machine and then injecting at a temperature above the foaming temperature of the blowing agent; Method for producing a foam comprising a. The method of claim 10, Screw injection temperature is 80 ~ 120 ℃ during the injection, the mold temperature is 150 ~ 200 ℃, the mold pressure is 150 ~ 400kg / cm ^{2 The} injection method of the foam manufacturing method characterized in that the foaming. A foam made from the composition of any one of claims 1 and 4 to 7. A molded article selected from the parts for footwear, interior and exterior materials for automobiles, automotive parts or packaging materials, comprising the foam of claim 12. The method of claim 13, Molded article, characterized in that the molded part is a shoe part used as a midsole or outsole.