JP5501886B2 - Foam, production method thereof and use thereof - Google Patents

Description

  The present invention relates to a foam (or foam seal material) useful for filling a gap in a building or a building, a manufacturing method thereof, and uses of the foam (or foam seal material).

  In a building or a building and installation work, a joint-sealing material is used for gaps between various members (for example, gaps in buried piping, formwork, etc.). This joint sealant is required to have rigidity (waist), compression recovery, etc. in addition to flexibility and flexibility. It has been proposed to use a foam as such a joint sealing material.

JP 2001-353663 A (Patent Document 1) uses a needle roll and a receiving roll provided with a heated through-hole forming needle, and while rotating the needle roll and the receiving roll, the extruded foam sheet of a polyolefin resin (such as polyethylene resin) is passed through a gap between the needle roller and receiving roll, through pores with a pore diameter of 0.02~1.0mm is provided 5 to 100 / cm ^2, open cell The rate is 70% or more, the apparent density is 0.013 to 0.18 g / cm ³ , the number of bubbles is 0.3 to 50 / mm ³ , and the average cell diameter is a predetermined condition in the extrusion direction, the width direction, and the thickness direction It is described that a polyolefin-based resin open-cell extruded foam sheet satisfying the above is obtained. This extruded foam sheet is excellent in flexibility, flexibility, thickness recovery after compression, sound absorption, etc., probably because it has a form in which closed cells and open cells are mixed. However, since the hole penetrates, the rigidity (waist) and repulsive force of the foamed sheet are reduced, and it is not suitable as a sealing material for filling the gap.

  In JP-A-2002-265661 (Patent Document 2), a closed-cell foam is continuously supplied between a pair of rotating rolls in which a large number of needle-like objects are implanted on the surface of at least one rotating roll. A method for producing an open-cell foam is disclosed in which needle-like objects on the surface of a rotating roll are pierced into the closed-cell foam and the closed cells of the closed-cell foam are communicated with each other to form open cells. Japanese Patent Application Laid-Open No. 2002-265662 (Patent Document 3) discloses a method of continuously supplying closed cell foam between a pair of rotating rolls while heating the needle-like material. In these methods, closed cells can be reliably communicated with each other without causing irregularities or wrinkles on the surface of the foam, thereby forming open cells. However, in the above method, since closed cells are made into continuous cells, the rigidity (waist) and repulsive force of the foam sheet are lowered, and it is not suitable as a sealing material for filling a gap.

JP 2001-353663 A (Claims, Effects of the Invention) JP 2002-265661 A (claims, effects of the invention) Japanese Patent Laid-Open No. 2002-265662 (Claims, Effects of Invention)

  Accordingly, an object of the present invention is to provide a foam (or foam seal material) that is excellent in flexibility and flexibility, and has high rigidity (waistness), compression recovery, and repulsive force, a method for producing the same, and a use thereof (sealing material). ) To provide.

  Another object of the present invention is to provide a foam (or foam seal material) having almost no needle hole openings or needle hole traces on the surface and having a smooth surface and excellent appearance characteristics, a method for producing the same, and use (sealing material). Is to provide.

  Still another object of the present invention is to provide a foam (or foam sealing material) having elasticity and impermeability or impermeability, a method for producing the same, and an application (sealing material).

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have (1) When a plurality of soft thermoplastic resins having different melting points are extruded and foamed from a die, the foaming gas in the bubbles has a low melting point during the bubble growth process. When the first thermoplastic resin film is ruptured to form open bubbles inside, (2) when the mold temperature is higher than the die temperature and extrusion foaming is performed, and the surface of the extruded foam is rapidly cooled, The second high-temperature thermoplastic resin solidifies and the foaming gas contributing to the internal communication cannot escape to the outside, and a foam having a cavity inside is obtained, (3) When a needle is inserted into the foam and the internal gas that causes the formation of the cavity is released to the outside, the needle hole is blocked by fusion in a closed cell phase, and a uniform surface can be formed. It was found that no foam was obtained. The present invention has been completed based on these findings.

  That is, the foam of the present invention includes a plurality of soft thermoplastic resins having different melting points, and has open cells and closed cells. The foam includes an open cell phase formed inside, a closed cell phase formed around the open cell phase, and a skin layer formed on the surface of the closed cell phase. The thermoplastic resin may include a plurality of thermoplastic resins selected from an olefin resin and a thermoplastic elastomer, for example, a plurality of ethylene resins selected from polyethylene and an ethylene-containing copolymer. The melting point difference between the plurality of thermoplastic resins may be, for example, about 20 to 75 ° C. The form of the foam is not particularly limited and can be selected according to the application. For example, the form may be a plate shape, a sheet shape, a column shape, or an irregular shape (a semicircular cross section, a trapezoidal cross section, etc.).

  In the method of the present invention, a foamable resin composition containing a plurality of soft thermoplastic resins having different melting points is extruded from a die, and during the growth of bubbles, the surface of the foam extruded from the die is rapidly cooled, and the foam The foam is manufactured by allowing a needle to enter the inside to escape the internal gas. In this method, the foamable resin composition is extruded under a condition where the mold temperature is higher than the die temperature to form open cells inside, and the surface of the foam is rapidly cooled to form closed cells. The inside of the foam may be allowed to penetrate into the foam in a heated state in which the inside is fluid) to escape or discharge the gas inside. Further, in order to efficiently close the needle hole, the foam may be cured after a plurality of needles have entered the inside of the foam.

  The present invention also includes a foam sealing material formed of the foam.

  In the present specification, the term “polyethylene” is used to mean a copolymer of ethylene and a small amount (for example, about 0.01 to 10 mol%) of an α-olefin in addition to an ethylene homopolymer. .

  In the present invention, since the foam has an open cell phase, a closed cell phase, and a skin layer sequentially from the inside to the outside, the open cell phase improves flexibility and flexibility, and the closed cell phase provides rigidity. (Waist), compression recovery and resilience can be improved. Therefore, these conflicting characteristics can be achieved. In addition, since it has a skin layer, there are almost no needle hole openings or needle hole traces on the surface, the surface is smooth and appearance characteristics can be improved, and elasticity and non-permeability or non-permeability (or barrier properties) are also achieved. I have. Therefore, the foam of the present invention is useful as a foam seal material (sealing material).

FIG. 1 is a schematic cross-sectional perspective view of the foam of the present invention. FIG. 2 is a schematic view for explaining the production process of the foam of the present invention.

  The foam of the present invention is formed of a foamable thermoplastic resin composition containing a plurality of soft thermoplastic resins having different melting points. FIG. 1 is a schematic cross-sectional perspective view of the foam of the present invention. In this example, a foam 1 having a quadrangular cross section is formed of an olefin resin (a plurality of ethylene resins having a melting point different from that of polyethylene), and the inside of the foam 1 has a continuous cell structure mainly composed of open cells. A bubble phase 2 is formed, and a closed cell phase 3 mainly having a closed cell structure is formed around the open cell phase, and a skin layer 4 is formed on the surface of the closed cell phase (or the surface of the foam). Is formed. Although the boundary between the open cell phase 2 and the closed cell phase 3 is not clear, the area ratio of the open cell phase 2 and the closed cell phase 3 in the cross-sectional shape of the foam 1 is approximately 60 / 40-80. / 20 or so. Further, in the manufacturing process, a needle is inserted into and extracted from the closed cell phase 3, but the needle hole penetrating the skin layer 4 is closed in the closed cell phase.

  The foam having such a cell structure has a single cell structure rather than a laminated structure in which a plurality of layers are laminated, and can improve flexibility, flexibility, rigidity, and compression recovery. Furthermore, since the needle hole is closed by the closed cell phase adjacent to the skin layer 4, non-permeability or non-permeability (barrier property) can be imparted. Therefore, if the gap between the members is filled, the gap can be tightly filled and sealed, and entry of moisture and the like from the outside can be inhibited. Therefore, the foam 1 is suitable as a sealing material.

  The soft thermoplastic resin may be soft as a whole composition, for example, olefin resin (ethylene resin, propylene resin, etc.), vinyl chloride resin (plasticized vinyl chloride resin, vinyl chloride-vinyl acetate). Copolymer), vinyl ester resins (polyvinyl acetate, vinyl acetate- (meth) acrylic ester copolymers, etc.), (meth) acrylic resins, thermoplastic elastomers, and the like. The soft thermoplastic resin usually contains at least one selected from olefin resins (particularly ethylene resins) and thermoplastic elastomers.

  Examples of the olefin resin include ethylene resins (such as polyethylene and ethylene copolymers), polypropylene resins (such as propylene copolymers such as polypropylene and propylene-ethylene copolymers), and polybutene resins. These olefinic resins can be used alone or in combination of two or more. Of these olefin resins (or soft thermoplastic resins), it is preferable to contain at least an ethylene resin.

Among the ethylene resins, examples of the polyethylene include high density polyethylene (HDPE), medium density polyethylene, low density polyethylene (LDPE), and linear low density polyethylene (LLDPE). In addition, high density polyethylene (HDPE) and medium density polyethylene are copolymerization of ethylene and a small amount (for example, about 0.01-5 mol%, especially about 0.1-3 mol%) of copolymerizable α-olefin. Includes coalescence. Linear low density polyethylene (LLDPE) is a copolymerizable α-ethylene with a small amount (for example, 0.01 to 10 mol%, preferably 1 to 8 mol%, particularly about 2 to 7 mol%) of ethylene. Copolymers with olefins (α-olefins other than ethylene) are also included. Examples of copolymerizable α-olefins (α-olefins other than ethylene) include α-C ₃₋ such as propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, and decene-1. Examples include ₁₀ olefins. These α-olefins can be used alone or in combination of two or more. LLDPE can be prepared using a metallocene catalyst. These polyethylenes may be used alone or in combination. Of these polyethylenes, low density polyethylene [low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc., especially LDPE, etc.] is preferable.

The ethylene copolymer (ethylene-containing copolymer) may be a copolymer of ethylene and a monomer (or polar monomer) other than ethylene. Examples of monomers (or polar monomers) other than ethylene include, for example, α-C _3-10 olefins such as propylene, butene-1, hexene-1, octene-1, and decene-1; vinyl acetate, propionic acid Organic acid vinyl esters such as vinyl and vinyl caproate; Acid group-containing monomers such as (meth) acrylic acid, maleic anhydride, and fumaric acid; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) (Meth) acrylic acid C _1-12 alkyl ester such as isopropyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 2-hydroxypropyl, (meth) acrylic Examples include (meth) acrylic acid esters such as glycidyl oxalate; halogen-containing monomers such as vinyl chloride and vinylidene chloride; and cyclic olefins. These non-α-olefin monomers can be used alone or in combination of two or more.

Cyclic olefins include, for example, monocyclic olefins [eg, cyclo C _3-10 alkenes such as cyclopentene and cycloheptene, cyclo C _3-10 alkadienes such as cyclopentadiene, etc.]; bicyclic olefins [eg, norbornenes (eg, 2-norbornene, 5-methyl-2-norbornene, 5,5- or 5,6-dimethyl-2-norbornene, 5-ethylidene-2-norbornene, 5-cyano-2-norbornene, 5-methoxycarbonyl-2 -Norbornene, 5-phenyl-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5,6-dimethoxycarbonyl-2-norbornene, 5,6-di (trifluoromethyl) -2-norbornene, _{C 4-20} bicycloalkyl, such as 7-oxo-2-norbornene Chloroalkene, etc.), norbornadienes (eg, 2,5-norbornadienes corresponding to the norbornenes exemplified above), etc., tricyclic olefins [eg, dihydrodicyclopentadienes (eg, dihydrodicyclopentadiene), dicyclopentadiene, etc. (Dicyclopentadiene, methyldicyclopentadiene, etc.), tricyclo [4.4.0.1 ^2,5 ] undeca-3,7-diene, tricyclo [4.4.0.1 ^2,5 ] undeca-3 C _6-25 tricycloalkadiene such as 8-diene, etc.], tetracyclic olefins [for example, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-methyltetracyclo [4.4.0.1 ^2,5 . C _7-30 tetracycloalkene such as 1 ^7,10 ] -3-dodecene], pentacyclic olefin [eg, pentacycloalkadiene (eg, C _10-35 pentacycloalkadiene such as tricyclopentadiene), etc. ], six cyclic olefins [e.g., hexa cycloalkenes (e.g., hexacyclo ^{[6.6.1.1 3,6 .0 2,7 .0 9,14]} -4- heptadecene _{C 12-40} hexacyclo such Alkene) etc.] and the like.

  These cyclic olefins can be used alone or in combination of two or more. Of these cyclic olefins, polycyclic olefins (especially bicyclic olefins such as norbornenes) are preferred.

Non-α-olefin monomers are vinyl acetate, (meth) acrylic acid, (meth) acrylic acid C _1-2 alkyl esters (such as ethyl acrylate), and bi- or tricyclic olefins (such as norbornenes). May be. The ethylene copolymer (ethylene-containing copolymer) may be a random copolymer or an alternating copolymer.

  The ethylene unit ratio (ethylene content) of the ethylene copolymer is 50 mol% or more (for example, about 60 to 99 mol%), preferably 65 mol% or more (for example, 65 to 65 mol%) with respect to the entire copolymer. About 98 mol%), more preferably about 70 to 97 mol% (for example, about 80 to 95 mol%), or about 60 to 99 mol% (for example, 75 to 98 mol%). . When the ethylene copolymer is a copolymer of ethylene and α-olefin, the ethylene content is in a range different from the ethylene content of the polyethylene (HDPE, LDPE, LLDPE, etc.), for example, 50 to 90 mol% ( For example, it can be selected from the range of about 55 to 87 mol%), preferably about 60 to 85 mol% (for example, 65 to 80 mol%).

  The number average molecular weight of the olefin resin (for example, ethylene resin) can be selected from a range of about 8,000 to 500,000, and is 10,000 to 300,000, preferably 15,000 to 200,000, and more preferably. May be about 20,000 to 150,000 (for example, 25,000 to 100,000). The number average molecular weight is a value measured using orthodichlorobenzene as a solvent at a measurement temperature of 140 ° C. in a gel permeation chromatography method (GPC method).

  The melting point of the olefin resin (for example, ethylene resin) may be about 65 to 170 ° C., preferably 70 to 160 ° C., and more preferably about 80 to 150 ° C. (for example, 90 to 120 ° C.). Further, the melting point of polyethylene may be, for example, about 100 to 132 ° C., preferably about 102 to 130 ° C. (for example, 105 to 125 ° C.), more preferably about 110 to 130 ° C. (for example, 115 to 125 ° C.). . Further, the melting point of the ethylene copolymer may be, for example, 65 to 150 ° C., preferably 70 to 140 ° C., more preferably about 80 to 130 ° C., depending on the type and content of the non-α-olefin. Good. In addition, it can replace with melting | fusing point and can also use glass transition temperature, and melting | fusing point and glass transition temperature can be measured with a differential scanning calorimeter.

  Under conditions of a temperature of 190 ° C. and a load of 21.2 N, the melt flow rate of the ethylene-based resin is, for example, 0.2 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, and more preferably 3 to 40 g / 10 minutes. It may be a degree. The melt flow rate of polyethylene according to ASTM D1238 is, for example, about 1 to 60 g / 10 minutes, preferably 3 to 50 g / 10 minutes, more preferably 5 to 40 g / 10 minutes (for example, 8 to 30 g / 10 minutes). It may be. The melt flow rate of polyethylene is, for example, 2 to 20 g / 10 minutes (for example, 4 to 8 g / 10 minutes), preferably 3 to 10 g / 10 minutes (for example, 4 at a temperature of 190 ° C. and a load of 21.2 N). About 5 to 7 g / 10 min), more preferably about 5 to 6.5 g / 10 min (for example, 5 to 6 g / 10 min).

  Examples of thermoplastic elastomers include olefin elastomers (block copolymers having polypropylene, polyethylene, etc. as hard segments and ethylene-propylene rubber, ethylene-propylene-diene rubber, etc. as soft segments), and styrene elastomers (styrene- Butadiene block copolymer (SBS block copolymer), styrene-isoprene block copolymer (SIS block copolymer), styrene-ethylene / butylene block copolymer (SEBS block copolymer), styrene-ethylene / propylene Block copolymers (SEPS block copolymers, etc.), polyester elastomers (polybutylene terephthalate and other aromatic polyesters are used as hard segments, and aliphatic polyesters (polyethylene (Rene adipate glycol, polybutylene adipate glycol, etc.) or aliphatic polyethers (polytetramethylene ether glycol, etc., block copolymers with soft segments), polyamide elastomers (nylon 6, nylon 12 and other polyamides, hard segments) And a block copolymer having the aliphatic polyester or aliphatic polyether as a soft segment), a polyurethane-based elastomer, and the like.

Among these resins, a plurality of resins having different melting points are used in combination as a resin composition. This resin composition preferably contains at least one selected from an ethylene-based resin and a thermoplastic elastomer as a base component. In particular, it preferably contains a plurality of ethylene resins selected from polyethylene and ethylene-containing copolymers. That is, the resin composition preferably contains at least an ethylene resin (polyethylene and / or ethylene copolymer) as a base component. Further, the resin composition may be composed of a plurality of ethylene resins. More specifically, the resin composition (for example, ethylene-based resin composition) includes polyethylene [especially, low density polyethylene such as LDPE and LLDPE] and ethylene copolymer [ethylene-such as ethylene-propylene copolymer] Ethylene- (copolymers such as α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-organic acid vinyl ester copolymers, ethylene- (meth) acrylic acid copolymers, ethylene-ethyl acrylate copolymers, etc.) And (meth) acrylic acid C _1-10 alkyl ester copolymer, ethylene-cyclic olefin copolymer such as ethylene-norbornene copolymer, and the like].

  In the present invention, among the resins, a plurality of resins having different melting points are used in combination. The melting point difference of the plurality of resins is selected from a range of, for example, about 10 to 100 ° C. (for example, 20 to 80 ° C.), and is usually 25 to 75 ° C., preferably 30 to 70 ° C. (for example, 35 to 65 ° C.). More preferably, it may be about 40 to 60 ° C. (for example, 45 to 55 ° C.). As the melting point difference is larger, it becomes easier to form internal open cells and closed cells that cover the open cells.

  The quantitative ratio of a plurality of resins having different melting points can be selected from a range in which open cells and closed cells can be formed. For example, a first resin (for example, polyethylene or a low melting point resin) and a second resin (for example, The ratio with the ethylene-containing copolymer or high melting point resin) can be selected from the range of the former / the latter (weight ratio) = 10/90 to 90/10 (for example, 20/80 to 85/15). 30/70 to 80/20, preferably 40/60 to 75/25 (for example, 35/65 to 95/5), 40/60 to 70/30 (for example, 45/55 to 65/35). May be.

  The soft thermoplastic resin (for example, ethylene resin) is used in combination with other resins, for example, styrene resin (for example, polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, etc.). May be. The weight ratio of the soft thermoplastic resin and the styrene resin is, for example, the former / the latter = 100/0 to 50/50, preferably 100/0 to 60/40, and more preferably about 100/0 to 70/30. There may be.

  The foamable resin composition may contain a foaming agent (or foaming aid) and a foam nucleating agent. Examples of the foaming agent include volatile foaming agents used for physical foaming and degradable foaming agents used for chemical foaming. Examples of volatile blowing agents include inert or non-flammable gases (nitrogen, carbon dioxide, chlorofluorocarbon, alternative chlorofluorocarbon, etc.), water, organic physical blowing agents [for example, aliphatic hydrocarbons (propane, n-butane, isobutane). , Pentane (n-pentane, isopentane etc.), hexane (n-hexane etc.), aromatic hydrocarbon (toluene etc.), halogenated hydrocarbon (trichlorofluoromethane etc.), ethers (dimethyl ether, petroleum ether) Etc.) and ketones (acetone etc.). Examples of the decomposable foaming agent include inorganic carbonates such as sodium bicarbonate and ammonium carbonate or salts thereof; organic acids such as citric acid or salts thereof (sodium citrate, etc.); 2,2′-azobisiso Azo compounds such as butyronitrile and azodicarboxylic amide; sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide; nitroso compounds such as N, N′-dinitrosopentamethylenetetramine (DNPT); azide compounds such as terephthalazide and the like . Of these blowing agents, aliphatic hydrocarbons such as butane and pentane, organic acids such as citric acid, or salts thereof (such as sodium citrate) are often used. These foaming agents may be used alone or in combination of two or more.

  The ratio of the foaming agent is 0.1 to 40 parts by weight, preferably 0.3 to 35 parts by weight, more preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the total amount of the plurality of resins (or resin components). It may be about a part.

  Examples of the foam nucleating agent include inorganic carbonates such as sodium bicarbonate and ammonium carbonate or salts thereof exemplified in the section of the foaming agent; organic acids such as citric acid or salts thereof (sodium citrate, etc.), and silicic acid. Examples thereof include compounds (such as talc, silica, zeolite), metal hydroxides (such as aluminum hydroxide), metal oxides (such as zinc oxide, titanium oxide, and alumina). These foam nucleating agents may be used alone or in combination of two or more. Among the foam nucleating agents, in particular, when a silicate compound such as talc is used, the cell structure can be made uniform.

  The ratio of the foam nucleating agent is, for example, 0.1 to 10 parts by weight, preferably 0.2 to 8 parts by weight, and more preferably 0 to 100 parts by weight of the total amount of the plurality of resins (or resin components). It may be about 3 to 5 parts by weight.

  The resin composition may contain a shrinkage inhibitor, for example, an ester of a fatty acid and a polyhydric alcohol, a fatty acid amide, or the like. More specifically, esters of fatty acids (eg, lauric acid, myristic acid, palmitic acid, stearic acid, etc.) and polyhydric alcohols (eg, glycerin, xylitol, sorbitol, mannitol, etc.) include, Examples include triglycerides, monostearic acid triglycerides, and the like. Examples of the fatty acid amide include palmitic acid amide and stearic acid amide. These shrinkage inhibitors may be used alone or in combination of two or more. The ratio of the shrinkage inhibitor is, for example, 0.01 to 30 parts by weight, preferably 0.05 to 20 parts by weight, and more preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the entire plurality of resins (the whole resin component). The weight may be about 0.5 to 10 parts by weight (for example, 1 to 5 parts by weight). The ratio of the shrinkage inhibitor is, for example, 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, more preferably 0.05 to 2 parts by weight (for example, 100 parts by weight of the foaming agent). 0.1-1 part by weight).

  The resin composition includes additives, for example, a compatibilizer, a bubble regulator, a stabilizer [an antioxidant (such as a hindered phenol antioxidant), an ultraviolet absorber, a heat stabilizer, a weather stabilizer, etc.] Antistatic agent, antiblocking agent, antifogging agent, organic or inorganic filler (calcium carbonate, carbon fiber, etc.), colorant (dye, pigment, etc.), dispersant, lubricant, mold release agent, lubricant, impact modifier , Colorants (dyes, pigments, etc.), plasticizers, surface smoothing agents, shrinkage inhibitors, flame retardants, biocides (bactericides, bacteriostatic agents, antifungal agents, antiseptics, insecticides, etc.), deodorants, etc. May be included. These additives may be used alone or in combination of two or more. The proportion of each additive is 0.1 to 30 parts by weight, preferably 0.15 to 20 parts by weight (for example, 0.2 to 0.2 parts by weight) with respect to 100 parts by weight of the total amount of the plurality of resins (or resin components). 15 parts by weight), more preferably about 0.5 to 10 parts by weight.

  The resin composition may be premixed with each component using a conventional method, for example, a mixer (such as a tumbler, V-type blender, Henschel mixer, Nauta mixer, ribbon mixer, mechanochemical apparatus, extrusion mixer). Good. Further, the foaming agent, the foam nucleating agent, and the additive component may be preliminarily contained in the resin composition (including resin pellets), respectively, or may be added or press-fitted into the resin composition in the foam molding process. .

  The foam of the present invention has open cells and closed cells. In particular, open cells and closed cells are distributed in a biased form. That is, an open cell phase mainly occupied by open cells is formed inside the foam, and a closed cell phase mainly occupied by closed cells is formed around the open cell phase. Furthermore, a skin layer is usually formed on the surface of the closed cell phase.

  The average diameter of the open cell of the open cell phase formed inside the foam is, for example, 0.1 to 3 mm (for example, 0.3 to 2.5 mm), preferably 0.5 to 2 mm (0.5 to 1). 0.5 mm), more preferably about 0.5 to 1 mm. In addition, the average diameter of the open cells is determined by measuring the short diameter and the long diameter of n bubbles, calculating the average of the short diameter and the long diameter [(short diameter + long diameter) / 2], and calculating the average value. Can be sought.

  The average diameter of the closed cells of the closed cell phase formed around the open cell phase is, for example, 0.1 to 2 mm (for example, 0.2 to 1.5 mm), preferably 0.2 to 1 mm (0.25). ˜0.8 mm), more preferably about 0.3 to 0.6 mm. The average diameter of the closed cells can be calculated in the same manner as the average diameter of the open cells.

  The area ratio of the open cell phase and the closed cell phase is not particularly limited and can be selected from the range of the former / the latter = 10/90 to 90/10 (for example, 20/80 to 80/20) depending on the application. For example, the former / the latter = 40/60 to 80/20 (for example, 50/50 to 80/20), preferably about 55/45 to 75/25 (for example, 60/40 to 70/30) Also good. Note that the boundary between the open cell phase and the closed cell phase is not clear because the closed cell and the open cell are mixed, but it can be calculated as an approximate average area ratio by observing the cross section. More specifically, when the cut surface of the foam is immersed in a colored aqueous solution containing a surfactant, the open cells absorb and color due to osmotic pressure, and the closed cells do not color. By utilizing this, the area ratio between the open cell phase and the closed cell phase can be determined by measuring the area ratio between the area of the colored portion and the closed cell portion that is not colored.

  The area ratio of open cells to the entire foam is, for example, 20 to 80% (for example, 25 to 75%), preferably 30 to 70% (for example, 35 to 65%), and more preferably 40 to 60%. It may be a degree.

  The foaming ratio of the foam can be selected according to the use from the range of about 5 to 150 times (for example, 10 to 100 times), for example, 10 to 70 times (for example, 15 to 65 times), preferably 20 to 50 times. Double (for example, 20 to 40 times) may be sufficient, and 10 to 30 times (for example, 15 to 25 times) may be sufficient.

The apparent density (g / cm ³ ) of the foam can be selected according to, for example, the expansion ratio, and is, for example, 0.014 to 0.1, preferably 0.02 to 0.05 (for example, 0.025 to 0). 0.05), more preferably about 0.033 to 0.1 (for example, 0.04 to 0.067). The apparent density D (g / cm ³ ) can be calculated by the following equation.

D = W / V
(Wherein, W represents the mass (g) of the test piece, and V represents the volume (cm ³ ) of the test piece)
Usually, a skin layer is formed on the surface of the foam. Therefore, the skin layer can ensure non-permeability or non-permeability (barrier property), and can improve water-stopping and sealing properties.

  The form of the foam of the present invention is not particularly limited and can be selected according to the form of the object to be protected (or article). For example, a one-dimensional shape such as a rod shape or string shape, a sheet shape, a film shape, or a two-dimensional network It may be a two-dimensional shape such as a (net) shape, or a three-dimensional shape such as a block shape, a plate shape, or a column shape. The foam usually has a plate shape, a sheet shape, a column shape, or an irregular shape (a semicircular cross section, a trapezoidal cross section, etc.). In the foam of such a form, at least one surface may be a flat surface or an uneven surface, one surface may be formed as an uneven surface, and the other surface may be an uneven surface. This uneven surface is often formed along the longitudinal direction of the foam. By forming the concavo-convex surface, the sealing material can be prevented from slipping at the sealing portion, and the sealing performance can be improved. The height of the concavo-convex portion is not particularly limited, and may be, for example, about 3 to 70% (preferably 5 to 50%, more preferably 10 to 30%) of the total thickness (maximum thickness) of the sheet-like foam. Good.

  The thickness (or average thickness) of the plate-like or sheet-like foam can be selected from a range of, for example, about 2 to 50 mm (eg, 3 to 30 mm), and is 5 to 25 mm, preferably 7 to 20 mm (eg, 7 to 17 mm). ) Degree or about 5 to 15 mm (for example, 8 to 12 mm). The dimension of the cross-section of the columnar foam may be, for example, a height of 5 to 100 mm (for example, 10 to 70 mm), preferably about 15 to 60 mm (for example, 20 to 50 mm), and a width of 5 It may be about 70 mm (for example, 10 to 50 mm), preferably about 10 to 40 mm (for example, 15 to 30 mm).

[Production method]
The foam having the structure includes a foaming process for extruding and foaming the foamable resin composition, a quenching process for quenching the surface of the extruded foam, and a needle entering (or piercing) the foam. Then, it can be manufactured by going through a gas release step for escaping or releasing the internal gas. The method of the present invention may further include a curing step for curing the foam after the gas releasing step.

  FIG. 2 is a schematic view for explaining the production process of the foam of the present invention. As shown in the figure, the foamable resin composition is supplied to an extruder 11, heated, melted and kneaded, and extruded (or discharged) through the mold 12 and the die 13 into the atmosphere. The method shown in the figure includes a foaming process in which the melt discharged from the base 13 is expanded by foaming, and the cell walls are broken to form open cells, and a discharge foam (foam in a molten state) that is extruded and foamed from the base 13. A rapid cooling process in which a mist-like water droplet is sprayed from the nozzle 14 and rapidly cooled against the peripheral surface of the body, and a bubble is in the downstream area of the quenching part and bubbles still enter the foam during the growth process. It includes a gas release step for releasing the gas inside the foam (piercing the needle) and a curing step for curing the foam that has undergone the gas release step. In this gas release step, a roll 15 having a plurality of needles (or pins) 16 on its surface is rotatably disposed in the downstream area of the quenching portion, and bubbles are still inside the foam during the growth process. A needle (or pin) 16 is inserted. Below, each said process is demonstrated in detail.

[Foaming process]
In the foaming step, the melt discharged with the extrusion from the die expands and expands, and bubbles grow. At that time, the extruded foam (molten foam) discharged from the die is extruded and foamed in an extrusion temperature region (a condition where the mold temperature is higher than the die temperature) in which open cells are formed. Mold temperature should just be higher than die temperature, and mold temperature is about 60-200 degreeC (preferably 70-180 degreeC, More preferably, 80-160 degreeC) according to the kind of resin, for example. Specifically, when polyethylene is used, the mold temperature is, for example, about 70 to 200 ° C, preferably about 80 to 150 ° C, and more preferably about 90 to 120 ° C. The temperature difference between the mold temperature and the die temperature is, for example, about 1 to 50 ° C. (for example, 20 to 40 ° C.), preferably 2 to 30 ° C., more preferably about 3 to 20 ° C. (for example, 5 to 10 ° C.). It may be.

  In such a foaming process, the melt discharged from the die is foamed by the bubble gas to grow the cell, and the foamed cell is destroyed, and an open cell bubble structure is mainly formed. In order to foam the resin composition, as described above, the foaming component (foaming agent, foaming aid) may be injected from the middle part of the extruder.

[Cooling or quenching process]
By rapidly cooling the peripheral surface of the discharged foam (molten foam) extruded and foamed from the die, a high melting point resin out of a plurality of resins having different melting points is solidified on the surface of the discharged foam, At the same time, the coating layer destruction (cell destruction) due to the gas in the bubbles is suppressed and closed cells are formed in the surface layer portion. Since the inside of the discharge foam is hot and fluid (or in a molten state), bubbles grow, and open cells are formed inside the discharge foam during the growth of the bubbles. Therefore, the surface of the discharged foam extruded from the die is usually cooled or rapidly cooled during the bubble growth process. By such a cooling or quenching process, an open cell phase having a cell structure of mainly open cells (or open cells) is formed inside, and a closed cell having a cell structure of mainly closed cells around the open cell phase. A phase is formed.

  In the above example, cooling is performed by spraying water, but the cooling fluid (cooling medium) is not limited to water, and other cooling fluids (for example, cooling air, liquid nitrogen, etc.) may be used. Good. A plurality of different cooling fluids may be combined, such as a combination of cooling with air and cooling with water spray. Usually, water that can be rapidly cooled is used. The temperature of the cooling fluid may be, for example, about 0 to 60 ° C., preferably 5 to 55 ° C., and more preferably about 10 to 50 ° C.

  The thickness (or volume ratio) of the closed cell phase (a bubble phase mainly having a cell structure of closed cells) can be adjusted by the flow rate of the cooling medium (amount of spray, etc.). That is, a closed cell phase having a larger thickness (or volume ratio) can be formed as the surface temperature of the discharged foam is lowered by cooling. For example, in an ethylene resin composition (for example, a resin composition containing polyethylene and an ethylene copolymer), the surface temperature of the discharged foam is 30 to 75 ° C. (preferably 40 to 70 ° C., more preferably 45 to 65 ° C. It is preferable to rapidly cool to about 0 ° C., particularly 50 to 60 ° C.

  The distance of the rapid cooling part (for example, spraying part) from a nozzle | cap | die may be about 30-250 mm, for example, Preferably it is 50-200 mm, More preferably, it is about 75-150 mm (for example, 75-125 mm).

[Gas release process]
In the discharged foam that has undergone the cooling step, the foamed gas that contributed to the formation of internal open cells (open cells) accumulates inside the foam and cannot be discharged to the outside. The open cell is destroyed and a cavity is formed, which impairs commercial value.

  Therefore, a needle is inserted (or stabbed) into the foam that has undergone the cooling process, and the internal gas is allowed to escape or release, thereby generating a foam without a cavity inside. The penetration or piercing of the foam by the needle is performed in a bubble growth process inside the foam (the inside of the foam is in a fluid state or a melted state).

  The thickness (or volume ratio) of the closed cell phase can be adjusted by the number of needles that enter the foam. That is, when the number of needles that enter the foam is increased, the thickness (or volume ratio) of the closed cell phase can be increased. Therefore, it is effective to allow a plurality of needles to enter the foam.

The length of the needle (or pin) is only required to reach the open cell phase, and is, for example, 3 to 30 mm (preferably 5 to 25 mm, more preferably 10 to 20 mm) depending on the thickness ratio of the open cell phase. You may select from the range of a grade. The thickness of the needle (or pin) may be, for example, about an average diameter of 0.1 to 2.5 mm (for example, 0.5 to 2 mm, preferably 0.7 to 1.5 mm). As the thickness of the needle (or pin) is reduced, the trace of the needle hole can be prevented from remaining on the surface of the final product. The average density (lines / cm ² ) of the needle (or pin) is usually 0.1 to 10 (for example, 0.3 to 8), preferably 0.5 to 7 (for example, 0.5 to 6), More preferably, it may be about 0.7 to 5 (for example, 1 to 1.8). Moreover, you may make a needle penetrate | invade into a foam over multiple times. For example, the foam may be sequentially penetrated or pierced by a plurality of needle rolls or pin rolls that are rotatably arranged at intervals in the foam traveling direction.

  In addition, the roll diameter of the needle roll (or pin roll) is, for example, 50 to 200 mmφ (for example, 70 to 150 mmφ, preferably 80 to 120 mmφ), and the pitch of the needle (or pin) is 10 to 100 mm (for example, 20 to 80 mm). , Preferably 30 to 60 mm, more preferably about 35 to 50 mm), and the number of rotations of the roll is, for example, 10 to 170 rpm (for example, depending on the extrusion speed of the foam and the outer peripheral length of the needle roll) 25-150 rpm, preferably 50-130 rpm, more preferably 75-125 rpm).

  In many cases, the needle is inserted and removed while the inside of the foam is still hot. For example, in an ethylene resin composition (for example, a resin composition containing polyethylene and an ethylene copolymer), the internal temperature is 50 to 80 ° C. (preferably 60 to 78 ° C., more preferably 65 to 77 ° C., particularly 70 It is preferable to pierce a foam of about ~ 76 ° C) with a needle.

  The needle (or pin) may be stabbed with foam with or without heating, and the intrusion or piercing site of the needle (or pin) is not particularly limited, and is the upper and lower surfaces of the discharge foam. It may be a side wall surface. When the needle is stabbed into the foam by the gas release step and the foam is removed from the foam, the internal gas is released to the outside, and the cells are solidified with natural cooling to form a foam structure.

  The distance of the center of the needle roll from the base is, for example, 200 to 500 mm, preferably 250 to 400 mm, more preferably about 270 to 350 mm, or about 250 to 350 mm.

[Curing process]
When the pressure inside the foam reaches equilibrium with the atmospheric pressure due to the release of the internal gas, the needle hole is closed and a non-permeable or non-permeable foam is obtained. The reason why the needle hole is blocked is not clear, but the needle hole is blocked by the elasticity of the closed cell phase, and the inside of the foam is still hot. It is conceivable that the hole is blocked. In order to reliably close the needle hole, it is preferable to cure the foam after the needle has been inserted into the foam.

  Curing of the foam can be performed, for example, by leaving it in the air at a temperature of about 20 to 60 ° C. (for example, 30 to 50 ° C.) for a predetermined time (for example, 1 day to 1 week).

  The foam thus obtained is uniform without voids inside, and has an open cell phase and a closed cell phase. Therefore, the foam of the present invention has both the advantage of the open cell structure and the advantage of the closed cell structure.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
A resin composition having the following formulation is put into a tandem extruder (first stage: φ50 mm, second stage: φ65 mm), and 8 parts by weight of butane gas is injected under pressure from the middle of the first stage extruder with a second stage. After cooling to the foaming region in the eye extruder and extruding from the die at a die temperature of 102 ° C.> 97 ° C., and extruding from the die, water is supplied to the outer periphery of the discharge foam at a water amount of 40 g / min. After spraying in the form of a mist, the rotating drum with 8 needles (φ1.0 mm × length 12 mm) attached at equal intervals in the outer circumferential direction of the drum (outer diameter 100 mmφ) is applied to the side of the discharge foam to invade the needle The internal foaming gas was discharged to obtain a long foam (cross-sectional width 20 mm × thickness 28 mm). In addition, the surface temperature (A) of the discharge foam immediately after discharging from a nozzle | cap | die, and the surface temperature (B) of the discharge foam in the quenching part which is located in the downstream direction 10cm away from the nozzle | cap | die, and is sprayed by the water spray from a nozzle And a rotating drum provided with a needle in the downstream part 20 cm away from the quenching part to pierce the foam, and the internal temperature of the foam in the downstream part (C) 200 cm away from the rotating drum is distant. It measured with the infrared temperature measuring apparatus (Yokogawa Electric Corporation make 53007-J). As a result, the surface temperature (A) was 84 ° C., the surface temperature (B) was 55 ° C., and the internal temperature (C) was 74 ° C.

[Resin composition]
LDPE (Tosoh Corporation, Petrocene 202) 90 parts by weight EVA: Ethylene vinyl acetate copolymer (Tosoh Corporation, Ultrasen 631) 10 parts by weight Shrinkage inhibitor (stearic acid monoglyceride, Boehringer Ingelheim Chemicals) Acty Bex 325) 3 parts by weight Nucleating agent (Eiwa Chemical Co., Ltd., EE275) 1.2 parts by weight Comparative Example 1
A foam was obtained in the same manner as in Example 1 without using a rotating drum.

Comparative Example 2
A foam was obtained in the same manner as in Example 1 except that the resin composition having the following formulation was used.

[Resin composition]
LDPE (Tosoh Corp., Petrocene 202) 100 parts by weight Anti-shrinkage agent (Boehringer Ingelheim Chemicals Co., Ltd. Activex 325) 3 parts by weight Nucleating agent (Eiwa Kasei Co., Ltd. EE275) 1.2 parts by weight And Examples The foaming ratio, dimensions, and compressive strength of the foams obtained in the comparative examples were measured. The expansion ratio was measured based on the following formula.

B = (V / W) × Z
(Wherein, W is the mass (g) of the test piece, V is the volume (cm ³ ) of the test piece, and Z is the resin density of the test piece)
Compressive strength is measured by using a hardness tester (Yasuda Seiki Seisakusho: LR10K) and compressing a test piece cut to a length of 5 cm in the longitudinal direction until the height reaches 50% (load is applied to a 20 mm wide surface). Measured by compression). The results are shown in Table 1.

In Table 1, in Example 1, a good product having a high compressive strength and uniform inside was obtained. In Comparative Example 1, a cavity was generated inside and was a defective product. In Comparative Example 2, the foam is obtained in closed cell structure, compressive hardness is large and 12N / cm ^2, greater than 5.5 N / cm ² are obtained as a sealing material, flexibility and flexible Was inferior.

  In addition, the foam of Example 1 has a closed needle hole, a small amount of water absorption per volume, can suppress water penetration into the interior required by the sealing material, and has water-stopping properties. It was. The amount of water absorption per volume was determined by waterproofing the cut surfaces at both ends of the test piece cut to a length of 5 cm in the longitudinal direction to prevent water from penetrating into the internal open cell phase. After being immersed in water for 24 hours, the amount of water absorption is expressed in weight%.

Examples 2-4 and Comparative Examples 3-5
A foam was produced in the same manner as in Example 1 except that the water spray amount (unit: g / min) and the thickness of the needle (length: 12 mm) were changed. In addition, the surface temperature (A) of the discharge foam immediately after discharging from a nozzle | cap | die, the surface temperature of the discharge foam in the quenching part by the water spray from the nozzle arrange | positioned in the location 10cm in the downstream direction from the nozzle | capacitance ( B) was measured with a far-infrared temperature measuring device (Yokogawa Electric Corporation 53007-J). Further, a rotating drum provided with a needle is disposed in the downstream portion 20 cm away from the quenching portion to pierce the foam, and the internal temperature of the foam in the downstream portion (C) 200 cm away from the rotating drum is infrared. Measured with a temperature measuring device.

  About the obtained foam, the thickness of the closed cell phase was measured as follows. That is, the cut surface of the foam was immersed in a colored aqueous solution containing a surfactant, and the thickness of the uncolored portion without water absorption was measured. The presence or absence of traces of needle holes on the surface of the molded body was visually observed, the test sample was submerged in water at a temperature of 20 ° C. for 24 hours, and the water absorption was measured to measure the water absorption rate (% by weight). The results are shown in Table 2.

  As apparent from Table 2, the thickness of the independent foam layer increases as the water spray cooling flow rate increases, and the surface temperature B and the internal temperature C decrease. Further, as the needle thickness is smaller, the needle hole trace is not observed. In addition, since the foams of Examples 2, 3 and 4 were filled with the needle marks on the surface thereof, the water absorption amount was about 1% by volume and showed high water blocking properties. On the other hand, since the foams of Comparative Examples 3 to 5 have needle marks and water absorption, the water stoppage cannot be improved.

  The foam of the present invention has improved flexibility and flexibility, as well as high rigidity (waist), compression recovery, and repulsion. In addition, since it has a skin layer, there are almost no needle hole openings or needle hole traces on the surface, the surface is smooth and appearance characteristics can be improved, and elasticity and non-permeability or non-permeability (or barrier properties) are also achieved. I have. Therefore, the foam of the present invention is useful as a foam seal material (sealing material). For example, gaps in housing-related parts (gap around walls and pillars, gaps around water, etc.), gaps related to sewage work (drainage grooves, gaps around culverts, etc.), furniture (clearance gaps), interior materials such as the interior of a car It is useful as a sealing material for filling joints and sealing joints.

  Furthermore, since it has an open cell phase and a closed cell phase, the foam of the present invention includes a cushion material, a buffer material (buffer protection material), a packaging material, a sound absorbing material, a hygroscopic material, a vibration isolating material, a heat insulating material, and the like. Can also be used.

DESCRIPTION OF SYMBOLS 1 ... Foam 2 ... Open cell phase 3 ... Closed cell phase 4 ... Skin layer 14 ... Nozzle 15 ... Roll 16 ... Needle

Claims (8)

  A foam comprising a plurality of soft thermoplastic resins having different melting points and having open cells and closed cells, and an open cell phase formed therein, and a closed cell phase formed around the open cell phase A foam comprising a skin layer formed on the surface of the closed cell phase.   The foam according to claim 1, wherein the thermoplastic resin includes a plurality of thermoplastic resins selected from olefin-based resins and thermoplastic elastomers.   The foam according to claim 1 or 2, comprising a plurality of ethylene resins selected from polyethylene and an ethylene-containing copolymer and having a melting point difference of 20 to 75 ° C.   The foam according to any one of claims 1 to 3, which has a plate shape, a sheet shape, a column shape, a semicircular cross section or a trapezoidal cross section.   A foamable resin composition containing a plurality of soft thermoplastic resins having different melting points is extruded from a die, and in the process of bubble growth, the surface of the foam extruded from the die is rapidly cooled, and a needle is inserted into the foam. The foam manufacturing method according to claim 1, wherein the internal gas is allowed to escape.   While the foam temperature is higher than the die temperature, the foamable resin composition is extruded to form open cells inside, while the foam surface is rapidly cooled to form closed cells. The manufacturing method according to claim 5, wherein a plurality of needles are allowed to enter to escape the internal gas.   The manufacturing method according to claim 5 or 6, wherein the foam is cured after the needle has entered the inside of the foam.   The foaming sealing material formed with the foam in any one of Claims 1-4.

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