KR20150027031A - Thermoplastic resin foam and foam-based sealing material - Google Patents

Abstract

It is an object of the present invention to provide a resin foam and a foamed sealing material which can realize excellent workability by imparting significant anisotropy to shear fracture in a specific direction while maintaining flexibility. Wherein the foam has a maximum breaking strength Smax of 0.1 MPa to 3 MPa and a ratio Smax of a maximum breaking strength Smax and a ratio Smin of a breaking strength Smin in an orthogonal direction with respect to a direction showing a maximum breaking strength / Smin is from 1.5 to 6. The breaking extension SSmax in the direction indicating the maximum breaking strength is 200% or less and the breaking extension SSmax in the direction indicating the maximum breaking strength and the breaking extension SSmin in the direction orthogonal to the direction indicating the maximum breaking strength It is preferable that the breaking extension ratio SSmax / SSmin is 1.5 to 6.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a thermoplastic resin foam and a foaming-

The present invention relates to a thermoplastic resin foam and a foamed sealing material.

Background Art [0002] Conventionally, a resin foam is used as a gasket material for portable telephones and portable information terminals, or as a wrapping sheet or tape, a sealing tape, a protective sheet or a tape.

Examples of the resin foam include compression molded urethane resin foam and highly foamed urethane foam of microcells having an open celled low-foamed structure, and foamed polyethylene foam having a closed cell ratio of about 30 and a density of 0.2 g / Cm < 3 > or less (see Patent Documents 1 and 2). It is produced in the form of a sheet or a tape by extrusion of a resin whose drawing or surface shape is controlled.

Such a resin foam is usually applied by being processed into a predetermined shape and fixed to a predetermined portion. However, since the resin foam is flexible and easily broken, there is a case where unintentional breaking occurs at the time of processing or fixing there was. In addition, a large load is applied to cutting or shearing in a predetermined direction, and it is difficult to extend in an unintended direction or breakage of the blade during cutting or shearing, or to form a breaking device by extension, It is not satisfactory for the hand cuttability at the time of processing.

Japanese Patent Application Laid-Open No. 2005-227392 Japanese Patent Application Laid-Open No. 2007-291337

An object of the present invention is to provide a resin foam and a foamed sealing material which can realize good workability by imparting a significant anisotropy to a shear fracture in a specific direction while maintaining flexibility.

The present invention includes the following inventions.

(1) A resin foam comprising a thermoplastic resin,

The maximum breaking strength Smax of the foam is 0.1MPa to 3MPa, and

And the ratio Smax / Smin of the maximum breaking strength Smax to the breaking strength Smin in the orthogonal direction with respect to the direction showing the maximum breaking strength is 1.5 to 6. The resin foamed article according to claim 1,

(2) the elongation at break SSmax in the direction showing the maximum breaking strength is 200% or less,

(1), wherein a breaking extension (SSmax) in a direction showing the maximum breaking strength and a breaking extension (SSmax / SSmin) of a breaking extension (SSmin) in an orthogonal direction with respect to a direction showing a maximum breaking strength are 1.5 to 6.

(3) The bubble size Cmax in the direction showing the maximum breaking strength and the ratio Cmax / Cmin of the bubble size Cmin in the orthogonal direction with respect to the direction indicating the maximum breaking strength is 1.2 to 5 Lt; / RTI >

(4) The resin foam according to any one of (1) to (3), wherein an apparent density is 0.01 to 0.2 g / cm 3.

(5) The resin foam according to any one of (1) to (4), which is obtained by a reduced pressure treatment of a thermoplastic resin composition impregnated with a high-pressure gas.

(6) The resin foam according to (5), wherein the gas is an inert gas.

(7) The resin foam according to (6), wherein the inert gas is carbon dioxide or nitrogen.

(8) The resin foam according to any one of (5) to (7), wherein the gas is a gas in a supercritical state.

(9) A foamed seal material comprising the resin foam according to any one of (1) to (8).

(10) The foamed seal material according to (9), which has a pressure-sensitive adhesive layer disposed on one side or both sides of the foam.

(11) The foamed sealing material according to (10), wherein the adhesive layer is disposed on the surface of the resin foam through the film layer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin foam and a foamed sealing material capable of realizing good workability by imparting a significant anisotropy to a shear fracture in a specific direction while maintaining flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a sample for carrying out a method for evaluating hand-cutability of a resin foam of the present invention. Fig.
2 is a schematic view showing an evaluation form of a sample in a method for evaluating hand cutability of the resin foam of the present invention.
3 is a schematic view of a main part in a manufacturing process for explaining a stretching method of the resin foam of the present invention.

The resin foam of the present invention is a foam containing a thermoplastic resin and is obtained by foaming or molding the thermoplastic resin composition. The shape of the resin foam of the present invention is not particularly limited and may be any shape such as a mass, a sheet, or a film.

[Physical Properties of Resin Foam]

The resin foam of the present invention has a maximum breaking strength Smax of 0.1 to 3 MPa, preferably 0.1 to 2 MPa, more preferably 0.2 to 2 MPa, still more preferably 0.3 to 2 MPa.

Here, the maximum breaking strength Smax means the largest breaking strength among the breaking strengths of the resin foam in various directions.

In order to obtain such a breaking strength, first, the breaking strength of the resin foam in an arbitrary direction (for example, direction A) is measured, a center X is set on the axis A in the direction A, Rotate the shaft by 10 ° and measure the breaking strength in each direction indicated by the axis (total 18 directions). Among them, the fracture strength at a direction in which the maximum fracture strength is large (hereinafter sometimes referred to as " maximum fracture strength direction ") is selected and is referred to as maximum fracture strength Smax.

By having such a maximum breaking strength, a resin foam having appropriate strength can be obtained.

In the resin foam of the present invention, the direction showing the maximum breaking strength is generally the MD direction (flow direction).

The resin foam of the present invention is further characterized in that the ratio Smax / Smin of the maximum breaking strength Smax to the breaking strength Smin in the orthogonal direction with respect to the maximum breaking strength direction is 1.5-6, preferably 1.8-6 Preferably 2 to 6, and more preferably 2 to 5.

By having such rupture strength ratio, it is possible to remarkably improve anisotropy in shear fracture in a specific direction, so that good workability, particularly hand cutability, can be realized. Accordingly, it becomes possible to use the resin foam of the present invention as a tape which is easy to open requiring anisotropy, as a sheet excellent in workability on the site.

The resin foam of the present invention has a breaking elongation SSmax in the maximum breaking strength direction of preferably not more than 200%, more preferably not more than 180%, further preferably not more than 160%. Further, it is preferably at least 100%, and more preferably at least 105%.

By having such elongation at break, elongation at the time of processing or fixing can be prevented. In addition, it is possible to effectively prevent the breakage accompanying the elongation or the like of the tape when used as a tape. The elongation of the resin foam can be evaluated as the elongation at the time when a predetermined load is applied. For example, when the load is 0.5N, the soft-electrification property is less likely to elongate if it is 5.0% or less, which can be judged to be good. The softening property at a load of 1.0 N is less likely to be elongated if it is 10.0% or less, which can be judged to be good. The electrorheological property can be measured by the method described in Examples to be described later.

The resin foam of the present invention is further characterized in that the rupture elongation SSmax in the maximum rupture strength direction and the rupture elongation ratio SSmax / SSmin of the rupture elongation SSmin in the orthogonal direction with respect to the maximum rupture strength direction are preferably 1.5 to 6 Is from 2 to 6, more preferably from 2.5 to 6.

By having such a breaking elongation ratio, elongation in the orthogonal direction with respect to the maximum breaking direction is reduced, so that cutting in a specific direction can be made easier.

The resin foam of the present invention can be obtained by, for example, a method in which the foam structure has a closed cell structure or a semi-continuous, semi-continuous cell structure (a cell structure in which a closed cell structure and a semi-continuous cell structure are mixed, . Particularly, a bubble structure in which the closed cell ratio of the resin foam is 50% or less, preferably 40% or less, more preferably 35% or less is exemplified. With this range, air is easily released from the resin at the time of compressive deformation when the impact acts, and sufficient impact absorbability can be exhibited. In addition, a bubble structure in which the closed cell ratio of the resin foam is at least 10%, preferably at least 15%, more preferably at least 20%. With this range, it is possible to prevent the minute particles such as dust from passing through and to improve the dustproof performance.

The closed cell ratio can be measured by, for example, the method described in the Examples.

The resin foam of the present invention preferably further has a bubble size Cmax in the maximum breaking strength direction and a ratio Cmax / Cmin of the bubble size Cmin in the orthogonal direction to the maximum breaking strength direction of preferably 1.2 to 5 Is 1.2 to 4, more preferably 1.2 to 3.5, still more preferably 1.3 to 3.5.

Here, the bubble size is an average value of 10 bubble diameters measured by the following method.

First, the resin foam is cut in the vertical direction (thickness direction) with respect to the main surface of the resin foam with a cutter in parallel to the direction of the maximum breaking strength of the resin foam and the direction orthogonal to this direction, and a smooth cross section is produced. Subsequently, these cross sections are observed with a Keith microscope (for example, trade name "VHX-600" manufactured by Keans Co., Ltd.). Then, ten points are extracted from the large bubble size within the measurement range of 3000 mu m x 2500 mu m, the area of the bubble is converted into the diameter, and the average value thereof is determined to be the bubble diameter.

The resin foam of the present invention preferably has a cell diameter of 50 to 300 占 퐉, more preferably 70 to 300 占 퐉, in a vertical (thickness direction) cut plane parallel to the maximum breaking strength direction Preferably 100 to 300 mu m, and still more preferably 100 to 250 mu m. The bubble diameter in the vertical direction (thickness direction) parallel to the direction perpendicular to the maximum breaking strength direction is preferably 10 to 200 占 퐉, more preferably 30 to 200 占 퐉, More preferably 50 to 200 占 퐉, and still more preferably 80 to 180 占 퐉.

In the resin foam of the present invention, by setting the bubble diameter of the foam to be within this range, anisotropy in the intended direction can be further realized, satisfactory workability and hand cutability can be ensured, So that it is possible to make a sharp surface.

The resin foam of the present invention preferably has an apparent density of preferably 0.01 to 0.20 g / cm 3, more preferably 0.01 to 0.15 g / cm 3, still more preferably 0.01 to 0.10 g / cm 3, 0.02 to 0.08 g / cm3. When the apparent density is within this range, sufficient strength can be ensured, good workability (particularly punching workability) can be obtained, and flexibility can be secured at the same time.

The resin foam of the present invention has a tensile modulus of preferably 5.0 to 14.0 MPa, more preferably 5.5 to 13.5 MPa, still more preferably 6.0 to 13.0 MPa. By setting this range, plastic deformation does not occur when the resin foam is pulled, and it is possible to effectively prevent extension and breakage in unintended directions. As a result, the toughness is low and excellent workability can be exhibited.

The tensile modulus is determined by a tensile test according to JIS K 6767.

[Material of Resin Foam]

The resin foam of the present invention is formed by a resin composition containing a thermoplastic resin or a thermoplastic resin. Examples of the thermoplastic resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, copolymers of ethylene and propylene, and copolymers of ethylene and propylene with other? -Olefins (e.g., butene- 1, hexene-1, 4-methylpentene-1, etc.), copolymers of ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylic ester, methacrylic acid, methacrylic acid ester, vinyl alcohol ); Polyolefin-based resins such as polyolefin-based resins; Styrene-based resins such as polystyrene and acrylonitrile-butadiene-styrene copolymer (ABS resin); Polyamide resins such as 6-nylon, 66-nylon and 12-nylon; Polyamideimide; Polyurethane; Polyimide; Polyetherimide; Acrylic resins such as polymethyl methacrylate; Polyvinyl chloride; Polyvinyl fluoride; Alkenyl aromatic resins; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonates such as bisphenol A-based polycarbonate; Polyacetal; Polyphenylene sulfide, and the like.

The thermoplastic resins may be used alone or in combination of two or more. When the thermoplastic resin is a copolymer, any copolymer of a random copolymer and a block copolymer may be used.

As the thermoplastic resin, a polyolefin-based resin is suitable from the viewpoints of properties such as mechanical strength, heat resistance, chemical resistance and the like, and molding surfaces such as easy melting and thermoforming.

As the polyolefin-based resin, a resin of a type having a wide molecular weight distribution and having a shoulder on the high-molecular-weight side, uncrosslinked type resin (slightly crosslinked type resin), long chain branched type resin and the like are suitably used.

The thermoplastic resin includes a rubber component and / or a thermoplastic elastomer component.

Since the rubber component and the thermoplastic elastomer component have, for example, a glass transition temperature of room temperature or lower (for example, 20 ° C or lower), flexibility and shape conformability when formed into a resin foam become very good.

The rubber component and the thermoplastic elastomer component are not particularly limited as far as they have rubber elasticity and can foam, and examples thereof include natural or synthetic rubber such as natural rubber, polyisobutylene, polyisoprene, chloroprene rubber, butyl rubber and nitrile butyl rubber ; Olefinic elastomers such as ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, polybutene and chlorinated polyethylene; Styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers and hydrogenated products thereof; Polyester-based elastomer; A polyamide-based elastomer; And various thermoplastic elastomers such as polyurethane-based elastomers.

These may be used alone or in combination of two or more.

Among them, as the rubber component and / or the thermoplastic elastomer component, an olefin-based elastomer is preferable. The olefinic elastomer has good compatibility with the polyolefin-based resin exemplified as the thermoplastic resin.

The olefinic elastomer may be of a type having a structure in which the resin component A (olefin resin component A) and the rubber component B are micro-phase-separated. Alternatively, the resin component A and the rubber component B may be physically dispersed, or the resin component A and the rubber component B may be dynamically heat treated (dynamic crosslinking thermoplastic elastomer, TPV) in the presence of a crosslinking agent.

Particularly, as the olefin elastomer, a dynamic crosslinking thermoplastic olefin elastomer (TPV) is preferable.

The dynamic crosslinking thermoplastic olefin elastomer has a higher elastic modulus and a lower compression set than TPO (non-crosslinkable thermoplastic olefin elastomer). Thereby, the recoverability is good, and when the resin foam is used, it exhibits excellent recoverability.

As described above, the dynamic crosslinking thermoplastic olefinic elastomer is obtained by dynamically heat-treating a mixture containing a matrix-forming resin component A (olefin-based resin component A) and a domain-forming rubber component B in the presence of a cross- And is a multicomponent polymer having a sea-island structure in which crosslinked rubber particles are finely dispersed as a domain (balloon) in a resin component A which is a matrix (marine).

Examples of the dynamic crosslinking thermoplastic olefin elastomer include those disclosed in Japanese Patent Application Laid-Open Nos. 2000-007858, 2006-052277, 2012-072306, 2012-057068 Japanese Patent Application Laid-Open No. 2010-241897, Japanese Patent Laid-Open Publication No. 2009-067969, Japanese Patent Publication No. 03/002654, Zeosome (manufactured by Nippon Zeon Co., Ltd.), Thermoran (Manufactured by Mitsubishi Chemical Co., Ltd.), "Sarlink 3245D" (manufactured by Toyobo Co., Ltd.), and the like.

When the resin constituting the resin foam of the present invention contains a rubber component and / or a thermoplastic elastomer component together with the thermoplastic resin, the content thereof is not particularly limited. For example, the ratio of the thermoplastic resin and the rubber component and / or the thermoplastic elastomer component in the resin constituting the resin foam of the present invention is preferably 70/30 to 30/70, More preferably 60/40 to 30/70, still more preferably 50/50 to 30/70, still more preferably 60/40 to 10/90, 58/42 to 10/90, 55 / 45 to 10/90. If the proportion of the rubber component and / or the thermoplastic elastomer component is too small, the cushion property of the resin foam tends to be lowered or the recoverability after compression tends to deteriorate. On the other hand, if the ratio of the rubber component and / or the thermoplastic elastomer component is too large There is a tendency that gas escapes easily at the time of forming the foam, and it becomes difficult to obtain a foam with high foamability.

In the resin foam of the present invention, in order to realize the flexibility at the time of high compression and the shape recovery after compression, that is, in order to enable the large deformation and not to cause the plastic deformation, Suitable. From this viewpoint, in the resin foam of the present invention, it is preferable to include a rubber component and / or a thermoplastic elastomer component together with the above-mentioned thermoplastic resin as a constituent resin.

The resin foam of the present invention preferably further contains a nucleating agent. When a nucleating agent is contained, the cell diameter can be easily adjusted, a suitable flexibility can be obtained, and a foam excellent in cutting workability can be obtained.

Examples of the nucleating agent include oxides and complex oxides such as talc, silica, alumina, zeolite, calcium carbonate, magnesium carbonate, barium sulfate, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, mica and montmorillonite, Sulfates, metal hydroxides; Carbon particles, glass fibers, and carbon tubes. The nucleating agents may be used alone or in combination of two or more.

The average particle diameter of the nucleating agent is not particularly limited, but is preferably 0.3 to 1.5 탆, and more preferably 0.4 to 1.2 탆. By setting the average particle diameter to such a value, sufficient function as a nucleating agent can be exhibited. In addition, the nucleating agent can realize the high expansion ratio without piercing the cell wall.

The average particle diameter can be measured by a laser diffraction particle size distribution measurement method. For example, it can be measured (AUTO measurement) from a dispersion dilution of a sample by "MICROTRAC MT-3000" manufactured by LEEDS & NORTHRUP INSTRUMENTS.

The content of the nucleating agent in the resin foam of the present invention is not particularly limited and is preferably 0.5 to 150 parts by weight, more preferably 2 to 140 parts by weight, , And more preferably 3 to 130 parts by weight.

Since the resin foam of the present invention is constituted by a thermoplastic resin and therefore, it is easily burned, it is preferable that the resin foam contains a flame retardant.

As the flame retardant, an inorganic flame retardant which is a nonhalogen-nonanthymine type is preferable.

Examples of such inorganic flame retardants include metal hydroxides and hydrates of metal compounds. More specifically, aluminum hydroxide; Magnesium hydroxide; Hydrates of magnesium oxide or nickel oxide; And hydrates of magnesium oxide and zinc oxide. Among them, magnesium hydroxide is suitably used. The hydrated metal compound may be surface-treated. The flame retardant may be used alone or in combination of two or more.

In the resin foam of the present invention, the content of the flame retardant is preferably 5 to 70 parts by weight, more preferably 25 to 65 parts by weight, based on 100 parts by weight of the resin constituting the resin foam.

The resin foam of the present invention may further contain at least one aliphatic compound selected from a fatty acid, a fatty acid amide and a fatty acid metal soap having a polar functional group and a melting point of 50 to 150 캜. Of these, fatty acids and fatty acid amides are preferred.

When such an aliphatic compound is contained in the resin foam of the present invention, the bubble structure is hardly damaged at the time of processing (particularly punching processing), and the shape recoverability is improved and the processability (particularly punching processability) is further improved do. Such an aliphatic compound has a high crystallinity and has a function of forming a firm film on the resin surface when added to the thermoplastic resin (particularly, polyolefin resin) to prevent the wall surfaces of the bubbles forming the bubble structure from blocking each other .

Such an aliphatic compound is particularly liable to be precipitated on the surface of the resin foam, because the polyolefin resin containing a functional group having a high polarity is difficult to be used, and the above effect is easily exhibited.

The melting point of the aliphatic compound is preferably from 50 to 150 DEG C from the viewpoint of lowering the molding temperature at the time of foam molding of the resin composition, suppressing deterioration of the resin (particularly, polyolefin resin) And more preferably 70 to 100 ° C.

The fatty acid preferably has about 18 to 38 carbon atoms, and more preferably about 18 to 22 carbon atoms. Specific examples include stearic acid, behenic acid, 12-hydroxystearic acid and the like. Among them, behenic acid is particularly preferable.

The fatty acid amide is preferably a fatty acid amide having a fatty acid portion having a carbon number of about 18 to 38, and more preferably a carbon number of about 18 to 22, and may be any one of a monoamide and a bisamide. Specific examples thereof include stearic acid amide, oleic acid amide, erucic acid amide, methylenebisstearic acid amide and ethylene bisstearic acid amide. Above all, erucic acid amide is particularly preferable.

Examples of the fatty acid metal soap include salts of aluminum, calcium, magnesium, lithium, barium, zinc and lead of the above-mentioned fatty acids.

In the resin foam of the present invention, the content of the aliphatic compound in the resin foam is not particularly limited, but is preferably 1 to 5 parts by weight, more preferably 1.5 to 3.5 parts by weight, By weight, and more preferably 2 to 3 parts by weight. As a result, a sufficient pressure can be maintained in the resin during the foaming molding, and the content of the foaming agent (for example, an inert gas such as carbon dioxide) can be ensured and a high foaming magnification can be obtained.

The resin foam of the present invention may contain a lubricant. Thereby, the fluidity of the resin composition can be improved and the thermal degradation of the resin can be suppressed. The lubricants may be used alone or in combination of two or more.

Examples of lubricants include, but are not limited to, hydrocarbon-based lubricants such as liquid paraffin, paraffin wax, micro wax and polyethylene wax; Ester-based lubricants such as butyl stearate, stearic acid monoglyceride, pentaerythritol tetrastearate, hardened castor oil, and stearyl stearate. The content of the lubricant can be appropriately selected within a range not to impair the effect of the present invention.

The resin foam of the present invention may contain other additives as required. Examples of such additives include stabilizers such as anti-shrinking agents, anti-aging agents, heat stabilizers, anti-light agents such as HALS, antiwear agents, metal deactivators, ultraviolet absorbers, light stabilizers and antifade agents, antibacterial agents, antifungal agents, A coloring agent such as carbon black or an organic pigment, and a filler. Particularly when a dynamic crosslinking thermoplastic olefin elastomer is used, a composition containing an additive (for example, a coloring agent such as carbon black, a softener, etc.) may be used as a composition containing the same. These additives may be used alone or in combination of two or more.

The content of these additives can be appropriately selected within a range that does not impair the effects of the present invention.

[Production method of resin foam]

The resin foam of the present invention can be produced by using a resin composition obtained by mixing or kneading additives such as a thermoplastic resin (including a rubber component and / or a thermoplastic elastomer component), optionally a nucleating agent, an aliphatic compound, The resin composition can be produced by foaming or molding. In particular, the anisotropic structure of the bubbles can be formed by stretching.

The foaming method used for foaming or molding the resin composition is not particularly limited and examples of the foaming method include a commonly used method such as a physical method and a chemical method. A general physical method is a method in which bubbles are formed by dispersing a low boiling point liquid such as chlorofluorocarbons or hydrocarbons (foaming agent) with a resin and then heating to volatilize the foaming agent. In addition, a general chemical method is a method of forming bubbles by gas generated by thermal decomposition of a compound (foaming agent) added to a resin.

In the present invention, as the foaming method, a foam having a small cell diameter and a high cell density can be easily obtained, so that a method using a high-pressure gas as the foaming agent is preferable. In particular, it is preferable to use a high-pressure inert gas as the foaming agent.

As a method of using a high-pressure gas as a foaming agent, a method of impregnating a resin composition with a high-pressure gas and then reducing the pressure is preferable. More specifically, a method of forming a non- Impregnating the molten resin composition through a depressurizing step, a method of impregnating a molten resin composition under a pressurized state, and then forming the molten resin composition by molding under reduced pressure.

The inert gas is not particularly limited as long as it is inert and impregnable with respect to the resin as the material of the resin foam, and examples thereof include carbon dioxide, nitrogen and air. These gases may be mixed and used. Of these, carbon dioxide or nitrogen is preferable because the amount of the resin to be impregnated is large and the impregnation speed is high.

Further, from the viewpoint of accelerating the impregnation speed with the resin composition, it is preferable that the above-mentioned high-pressure gas (in particular, inert gas, further carbon dioxide) is a gas in a supercritical state. In the supercritical state, the solubility of the gas in the resin is increased, and high concentration can be incorporated. Further, at the time of rapid pressure drop after the impregnation, impregnation can be carried out at a high concentration as described above, so that the generation of bubble nuclei increases and the density of the bubbles generated by the growth of the bubble nuclei increases even if the porosity is the same. Can be obtained. For example, the critical temperature of carbon dioxide is 31 ° C and the critical pressure is 7.4 MPa.

As a method of foaming or molding the resin composition by a method using a high-pressure gas as a foaming agent, a resin composition is previously molded into a suitable shape such as a sheet form to obtain an unfoamed resin molded article (unfoamed resin molded article) There is a batch method in which the unfoamed resin molded article is foamed by impregnating with a high-pressure gas and releasing the pressure. There is also a continuous method in which the resin composition is kneaded together with a high-pressure gas under pressure, molded, and the pressure is released to simultaneously perform molding and foaming.

Examples of the method of forming the unfoamed resin molded article to be provided for foaming when the resin composition is foamed or molded in the batch mode include a method of molding the resin composition using an extruder such as a single screw extruder or a twin screw extruder; A method of uniformly kneading the resin composition using a kneader equipped with a roller such as a roller, a cam, a kneader or a Banbury type, press molding the resin composition to a predetermined thickness using a hot plate press or the like; A method of molding the resin composition using an injection molding machine, and the like. The unfoamed resin molded article may also be formed by other molding methods in addition to extrusion molding, press molding, and injection molding. The shape of the unfoamed resin molded article is not particularly limited and various shapes can be selected depending on the application, and examples thereof include a sheet shape, a roll shape, a plate shape, and a massive shape.

As described above, when the resin composition is foamed or molded by the batch method, the resin composition can be molded by an appropriate method to obtain an unfoamed resin molded article having a desired shape and thickness.

When the resin composition is foamed or molded by the batch method, the obtained unfrozen resin molded product is put into a pressure-resistant container (high-pressure container), and a high-pressure gas (in particular, inert gas and further carbon dioxide) A pressure impregnating step of impregnating a high-pressure gas in the resin, a decompressing step of releasing the pressure (usually up to atmospheric pressure) at the time when a sufficiently high-pressure gas is impregnated to generate bubble nuclei in the resin, And bubbles are formed in the resin through a heating step of heating the bubble nuclei by heating. The bubble nuclei may be grown at room temperature without providing a heating step.

In the continuous foaming or molding of the resin composition in the continuous mode, a high-pressure gas (particularly, an inert gas and further carbon dioxide) is injected (introduced) while kneading the resin composition using an extruder such as a single screw extruder or a twin screw extruder, (Usually atmospheric pressure) by extruding the resin composition through a kneading and impregnating step of impregnating a sufficiently high-pressure gas into the resin composition, a die provided at the tip of the extruder, and the like, Foaming or molding. In the kneading-impregnating step and the molding depressurization step, an extruder, an injection molding machine or the like may be used. When the resin composition is foamed or molded in a continuous system, a heating step of growing bubbles by heating may be provided, if necessary.

After the bubbles are grown in either the batch mode or the continuous mode, the shape may be fixed by sudden cooling by cold water or the like as necessary. The introduction of the high-pressure gas may be performed continuously or discontinuously. As a heating method for growing the bubble nuclei, a known method such as a water bath, an oil bath, a heat roll, a hot air oven, a far-infrared ray, a near-infrared ray, and a microwave can be employed.

Further, in the case of producing the resin foam of the present invention, it is necessary to give anisotropy to the resin foam by either the batch method or the continuous method after the above-mentioned process or after the above-described process.

Concretely, it is preferable to stretch by the following method.

For example, when the resin is extruded from a slit-shaped T-die or slit die 10 into a sheet form as shown in Fig. 3A, before the resin is cooled and solidified, the resin sheet 11 is melted Or in a semi-molten state, and pulling the nip roll (12); As shown in Fig. 3B, when the resin is extruded from a slit-shaped T-die or slit die 10 into a sheet, before the resin is cooled and solidified, the resin sheet 11 is fed to the roll 13 How to stretch and pull; As shown in Fig. 3C, a method of pulling the resin sheet 11 across the roll 13 a plurality of times so as not to slip; As shown in Fig. 3D, a method of bending the resin sheet 11 between rolls 13 so as not to slip; A method in which the resin sheet 11 is sandwiched between the endless belts 14 and brought into contact with both sides and pulled out by friction so as not to slip, as shown in FIG. 3E; As shown in Fig. 3F, there is a method in which it is brought into contact with the endless belt 14 and pulled out by the friction between the belt and the resin sheet 11 so as not to slip. 3, the resin sheet 11 is extruded in a ring form from a cylindrical die 20, and one of the rings is cut with a cutter or the like to form a sheet. For example, a method of putting it in the nip roll 12 and pulling it out.

In the case of carrying out the above-described method, if the speed at which the resin sheet is fed by a roll or a belt is defined as a molding speed, in order to form the anisotropic structure, the ratio of the resin extrusion speed and the molding speed is preferably from 1: 1.2 to 1 : 5 is preferable. By setting the thickness within this range, the resin sheet can be formed into an appropriately thin and elongated shape without crushing in the thickness direction, thereby ensuring the porosity, cushioning, and flexibility.

The shaping speed is not particularly limited, and is preferably set in the range of 2 m / min to 100 m / min in consideration of the fact that the resin sheet can be stably molded and the production efficiency is taken into consideration.

When the resin sheet is kneaded by a roll or a belt, it is preferable that the formed foam is pressure-applied so as not to be damaged in the thickness direction.

The amount of gas to be used for foaming or molding the resin composition is not particularly limited. For example, it is preferably 2 to 10% by weight, more preferably 2.5 to 8% by weight based on the whole resin component in the resin composition, More preferably 3 to 6% by weight. By setting this range, a foam having a high foaming ratio can be obtained without separating the gas in the molding machine.

In the gas impregnating step in the batch method for foaming or molding the resin composition or the kneading and impregnating step in the continuous method, the pressure at the time of impregnating the gas into the unfoamed resin molded product or the resin composition varies depending on the kind of gas, However, when carbon dioxide is used as the inert gas, it is preferably 6 MPa or more (for example, 6 to 100 MPa), more preferably 8 MPa or more (For example, 8 to 100 MPa). By setting the pressure to such a value, the bubble growth at the time of foaming can be controlled appropriately, the cell diameter can be reduced, and moreover, a good dustproof effect can be obtained. This is because the gas impregnation amount becomes an appropriate amount, the bubble nucleus formation rate can be controlled, and the bubble nucleus number formed can be adjusted to an appropriate number. Further, control of the cell diameter and the bubble density becomes easy.

The temperature at the time of impregnating the unexpanded gas into the unfoamed resin molded product or the resin composition in the gas impregnation step in the batch method for foaming or molding the resin composition or the kneading and impregnating step in the continuous method is not particularly limited, Or the kind of the resin, so that it can be selected from a wide range. For example, 10 to 350 DEG C in view of operability and the like. In the batch method, the impregnation temperature in the case of impregnating a sheet-shaped unfoamed resin molded article with a high-pressure gas is preferably 10 to 250 占 폚, more preferably 40 to 240 占 폚, and still preferably 60 to 230 占 폚 to be. In the continuous system, the temperature at which high pressure gas is injected into the resin composition and kneaded is preferably 60 to 350 占 폚, more preferably 100 to 320 占 폚, and still more preferably 150 to 300 占 폚. In the case of using carbon dioxide as the high-pressure gas, the temperature (impregnation temperature) at the time of impregnation is preferably 32 ° C or more (particularly 40 ° C or more) in order to maintain the supercritical state.

The decompression rate in the step of depressurization when the resin composition is foamed or molded by the batch method or the continuous method is not particularly limited and is preferably 5 to 300 MPa / second in order to obtain uniform microbubbles. The heating temperature in the heating step is, for example, 40 to 250 占 폚 (preferably 60 to 250 占 폚).

When the above method is used for foaming or molding the resin composition, it is possible to produce a resin foam having a high expansion amount, thereby making it possible to produce a thick resin foam. For example, when the resin composition is foamed or molded in a continuous manner, in order to maintain the pressure inside the extruder in the kneading and impregnating step, the gap of the die provided at the extreme end of the extruder should be as narrow as possible (usually about 0.1 to 1.0 mm ) do. Therefore, in order to obtain a thick resin foam, the resin composition extruded through a narrow gap is foamed at a high magnification. Conventionally, since the high expansion ratio can not be obtained, the thickness of the resin foam to be formed is limited to a small thickness (for example, 0.5 to 2.0 mm). On the other hand, it is possible to continuously obtain a resin foam having a thickness of 0.50 to 5.00 mm finally by foaming or molding the resin composition using a high-pressure gas.

Depending on the kind of the gas, the thermoplastic resin, the rubber component and / or the thermoplastic elastomer component used, for example, the apparent density, the breaking strength, the breaking extension, the bubble size and the hand cutting property, Or operating conditions such as the temperature, pressure and time in the kneading and impregnating step, the operating conditions such as the speed of depressurization in the depressurization step or the depressurization step, the temperature and the pressure, the heating temperature in the heating step after depressurization or after the depressurization, It can be adjusted by appropriately selecting and setting it.

In particular, the resin foam of the present invention is obtained by impregnating a resin composition containing at least a nucleating agent and an aliphatic compound in addition to a thermoplastic resin with a high-pressure gas (particularly, an inert gas) . As a result, it is possible to provide a bubble structure having a small average cell diameter and a low independent cell structure ratio, a high blending ratio, a good flexibility, a bubble structure which is difficult to deform or compress, A resin foam excellent in workability can be easily obtained.

The resin foam of the present invention is obtained by impregnating a resin composition containing at least a nucleating agent and an aliphatic compound having a particularly small average particle size in addition to a thermoplastic resin with an inert gas in a supercritical state and then decompressing the resin composition, And it is more preferable that it is formed through a step of stretching the foam. As a result, it is possible to obtain a bubble structure having a very small average cell diameter and a low independent cell structure ratio, a high blending ratio, a good flexibility, a bubble structure which is difficult to deform or compress, , It is possible to further inhibit the nucleophilic agent from piercing the bubble wall, and furthermore, since the anisotropy is very high, a resin foam excellent in workability can be easily obtained.

The resin foam of the present invention is a mixture of a thermoplastic resin and a rubber component and / or a thermoplastic elastomer component, and the ratio of the thermoplastic resin to the thermoplastic resin is 70/30 to 30/70 by weight, (Particularly, an inert gas) is impregnated into a resin composition containing at least 0.5 to 150 parts by weight of a nucleating agent and 1 to 5 parts by weight of an aliphatic compound per 100 parts by weight of the thermoplastic resin, It is preferable to form the through-holes.

[Foam sealant]

The foaming sealant of the present invention is a member including the resin foam. The shape of the foam seal member is not particularly limited, but a sheet shape (including a film shape) is preferable. The foam seal material may be constituted by, for example, a resin foam material only, or a pressure sensitive adhesive layer, a base material layer, or the like may be laminated on the resin foam material.

Particularly, the foamed sealing material of the present invention preferably has an adhesive layer. For example, when the foam seal material of the present invention is a sheet-shaped foam seal material, the pressure sensitive adhesive layer may be provided on one side or both sides thereof. If the foaming sealant has the adhesive layer, for example, the processing sheet can be provided on the foamed seal material with the adhesive layer interposed therebetween.

The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited and includes, for example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive (natural rubber pressure-sensitive adhesive, synthetic rubber pressure-sensitive adhesive, etc.), a silicone pressure-sensitive adhesive, a polyester pressure- Known pressure-sensitive adhesives such as a pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, and a fluorine-based pressure-sensitive adhesive can be appropriately selected and used. The pressure-sensitive adhesives may be used alone or in combination of two or more. The pressure sensitive adhesive may be any one of an emulsion pressure sensitive adhesive, a solvent pressure sensitive adhesive, a hot melt pressure sensitive adhesive, an oligomer pressure sensitive adhesive and a high pressure sensitive adhesive. Among them, an acrylic pressure-sensitive adhesive is preferable as the pressure-sensitive adhesive from the standpoint of prevention of contamination to an adherend.

The thickness of the adhesive layer is preferably 2 to 100 占 퐉, more preferably 10 to 100 占 퐉. The thinner the thickness of the adhesive layer, the better the effect of preventing adherence of dust and dirt to the end portion.

The adhesive layer may have any form of a single layer or a laminate, and may be either foamed or non-foamed. Among them, a non-foamable adhesive material layer is preferable.

In the foaming sealant of the present invention, the adhesive material layer may be provided via another layer (lower layer). Examples of such a lower layer include another adhesive layer, an intermediate layer, a primer layer, and a base layer (particularly, a film layer, a nonwoven layer, etc.). The lower layer may be a foamed layer or a porous layer, but it is preferably a non-foamable layer, more preferably a resin layer.

The adhesive material layer may be protected by a peeling film (separator, for example, peeling paper, peeling film or the like).

Since the foamed seal material of the present invention includes the resin foam of the present invention, it has good dustproofness, particularly good dynamic vibration resistance, and flexibility that can follow a minute clearance.

The foamed seal material of the present invention may be processed to have a desired shape, thickness, and the like. For example, it may be processed in various shapes in accordance with a device, a device, a housing, a member used, and the like.

The foamed seal material of the present invention is suitably used as a member used when a variety of members or parts are installed (mounted) on a predetermined site. Particularly, the foamed sealing material of the present invention is suitable as a member used in installing (mounting) a component constituting an electric or electronic device in a predetermined area in an electric or electronic device.

The various members or parts that can be installed or mounted using the foam member are not particularly limited, and examples thereof include various members or parts in electrical or electronic devices. Examples of such members or parts for electric or electronic devices include an image display member (display portion) (particularly, a small image display member) mounted on an image display device such as a liquid crystal display, an electroluminescence display, or a plasma display, An optical member such as a camera or a lens (particularly, a small-sized camera or a lens) mounted on a mobile communication device such as a "mobile phone" or a "portable information terminal", or an optical component.

As a suitable specific use form of the foamed sealing material of the present invention, for example, there is a case where a liquid crystal display (LCD), a liquid crystal display (LCD), or the like, and a housing And the like.

When the foamed sealing material of the present invention is provided on such a member or part, it is preferable to arrange the foamed sealing material so as to block the clearance. The clearance is not particularly limited and may be, for example, about 0.05 to 0.5 mm .

Hereinafter, the thermoplastic resin foam and the foamed sealing material of the present invention will be described based on examples.

(Example 1)

As the resin composition,

35 parts by weight of polypropylene,

60 parts by weight of the thermoplastic elastomer composition,

5 parts by weight of a lubricant,

10 parts by weight of a nucleating agent and

2 parts by weight of erucic acid amide (melting point 80 to 85 占 폚) were kneaded at 200 占 폚 with a biaxial kneader.

Here, the polypropylene is a resin having a melt flow rate (MFR) of 0.35 g / 10 min,

The thermoplastic elastomer composition contains 16.7% by weight of carbon black and is a blend of polypropylene (PP) and an ethylene / propylene / 5-ethylidene-2-norbornene terpolymer (EPT) (crosslinked olefin thermoplastic Elastomer, TPV), polypropylene: ethylene / propylene / 5-ethylidene-2-norbornene terpolymer = 10: 90 (by weight)

The lubricant was a master batch in which 10 parts by weight of polyethylene was blended with 1 part by weight of stearic acid monoglyceride,

The nucleating agent is magnesium hydroxide having an average particle diameter of 0.8 mu m.

Thereafter, the resin composition was extruded into a strand shape, water-cooled, cut into pellets, and molded.

The pellets were charged into a tandem-type single-screw extruder manufactured by Nihon Seiko Co., Ltd., and carbon dioxide gas was injected at 3.8% by weight at a pressure of 14 MPa (18 MPa) in an atmosphere at 220 캜. The carbon dioxide gas was sufficiently saturated and cooled to a temperature suitable for foaming. Thereafter, in order to obtain an anisotropic structure by extrusion from the die, the ratio of the resin extrusion speed to the molding speed is adjusted to be in the range of 1: 1.2 to 1: 2 to prevent the foam from loosening in the line, To obtain a sheet-form resin foam. This resin foam had a semi-continuous, semi-continuous bubble structure with a tensile elastic modulus of 9.3 MPa and a closed cell ratio of 32%.

(Example 2)

A sheet-like resin foam was produced in substantially the same manner as in Example 1, except that the thickness was adjusted to be 0.5 mm. This resin foam had a semi-continuous, semi-continuous bubble structure with a closed cell ratio of 32%. The soft magnetic properties at 0.5 N were 3.7% and the soft magnetic properties at 1.0 N were 7.2%.

(Comparative Example 1)

Urethane foam (main component: polyurethane, sheet shape, average cell diameter: 229 탆, apparent density: 0.24 g / cm 3) was prepared as an isotropic foam.

(Method of measuring the independent void ratio)

The closed cell ratio of the resin foam obtained in Examples and Comparative Examples was measured according to the following method.

From the obtained resin foam, a flat square test piece having a thickness of 5 cm on one side is cut out. Subsequently, the weight W1 (g) and the thickness (cm) of the test piece are measured, and the apparent volume V1 (cm3) of the test piece is calculated.

Subsequently, the obtained value is substituted into equation (1) to calculate the apparent volume V2 (cm < 3 >) occupied by the bubble. The density of the resin constituting the test piece is set to rho g / cm3.

(1)

(One)

Subsequently, this test piece is immersed in distilled water at 23 ° C so that the distance from the upper surface of the test piece to the water surface becomes 40 mm, and left for 24 hours. Thereafter, the test piece is removed from the distilled water to remove moisture adhering to the surface of the test piece. The weight W2 (g) of the obtained test piece is measured, and the open cell ratio F1 is calculated based on the equation (2). The closed cell ratio F2 is obtained from the open cell ratio F1.

(2)

(2)

(3)

(3)

(Tensile modulus)

The tensile test was carried out in accordance with JIS K 6767, and the strain was calculated on the basis of the following equation by the slope under the elastic region in the obtained stress-strain curve. That is, under the elastic region in the stress-strain curve, it was found by the ratio of the stress and the corresponding strain.

Tensile modulus (MPa) = stress / strain

(Flexible)

A. Flexibility (0.5N)

The resin foam was cut in the MD direction to prepare a sheet-shaped test piece having a thickness of 0.5 mm, a width of 3 mm and a length of 30 mm. The test piece was stretched in the longitudinal direction under a load of 0.5 N while one longitudinal end portion of the test piece was fixed, and the length of the test piece after stretching was measured. On the basis of the following formula, the toughness (%) was obtained.

(%) = 100 x [(length of test piece after stretching) - (length of initial test piece)] / (length of initial test piece)

When the elongation at break (0.5 N) is 5.0% or less, it is difficult to elongate and it can be judged to be good.

B. Tensile Properties (1.0 N)

The elongation at break (%) was determined in the same manner as in the tieability test (0.5 N) except that the load was 1.0 N.

When the elongation at break (1.0 N) is 10.0% or less, it is difficult to elongate and it can be judged to be good.

(evaluation)

The following evaluation was made on the sheets of the resin foam of the examples and the comparative examples. The results are shown in Table 1.

(Method of measuring apparent density)

A sample obtained by cutting the resin foam into 20 mm x 20 mm was used to calculate the apparent density (g / cm < 3 >) of the foam from the weight of the sample and buoyancy in the density meter.

(A method of measuring the maximum breaking strength Smax and the breaking strength Smin / breaking extension SSmax and SSmin)

First, the resin foam is measured for breaking strength in an arbitrary direction (for example, direction A), the center X is set on the axis A in the direction A, the axis is rotated by 10 degrees with respect to the center X, The breaking strength in each direction indicated by each axis was measured (18 directions in total). Among them, the fracture strength in the direction in which the fracture strength is the largest is selected, and this fracture strength is called the maximum fracture strength Smax.

Further, in the resin foam of the examples, the direction showing the maximum breaking strength Smax coincided with the MD direction. Therefore, the direction orthogonal to the direction showing the maximum breaking strength coincides with the TD direction.

The breaking strength was evaluated by measuring the strength and elongation at the break point by piercing the resin foam with a hole in the dumbbell No. 1 and performing a tensile test at a chuck distance of 50 mm and a tensile speed of 500 mm / And the breaking strength and breaking elongation, respectively.

(Method of measuring bubble size)

And cut in the vertical direction (thickness direction) with respect to the main surface of the resin foam with a cutter in parallel with the direction of the maximum breaking strength described below of the resin foam and a direction orthogonal to this direction and to produce a smooth cross section.

These sections were introduced into a Keith microscope (for example, trade name "VHX-600" manufactured by KYENS CORPORATION) and subjected to image analysis using analysis software (Win ROOF manufactured by MItani Shoji Co., Ltd.) of this instrument. In the measuring range of the resin foam of 3000 mu m x 2500 mu m, the bubble diameter was calculated from the pixel area of the image in terms of the diameter, and 10 points were extracted from those having a large bubble diameter. .

(Hand cutability)

As shown in Fig. 1, a sample 1 having a width of 40 mm and a length of 100 mm was prepared, and a sample 1a was formed in this sample 1 up to 50 mm at a position of 20 mm in width parallel to the longitudinal direction. As shown in Fig. 2, the sample 1 was fixed in the grip portion 2 of the tensile tester and pulled in the Z direction until the sample 1 was broken and separated at a tensile speed of 500 mm / min to obtain Sample 1 Was judged by the naked eye. It was evaluated that the hand cuttability was good when the positional deviation (Q in Fig. 1) from the infeed position to the fractured end was within 5 mm (20%).

According to Table 1, it was confirmed that the resin foams of Examples 1 and 2 had a large value of Smax / Smin and had remarkable anisotropy in shear fracture in a specific direction, and therefore, good workability could be realized.

INDUSTRIAL APPLICABILITY The present invention provides a resin composition which is excellent in flexibility, cushioning property and processability and which is useful as an insulator, a cushioning material, a sound insulating material, a vibration damping material, a shock absorber and a light shielding material for insulation materials, food packaging materials, clothing materials, building materials, Resin foams and foaming sealants, and can be widely used for various members.

1: sample
2:
10: T die or slit die
11: Resin sheet
12: Nip roll
20: Resin foam
21: Rollers

Claims (11)

A resin foam comprising a thermoplastic resin,
The maximum breaking strength Smax of the foam is 0.1MPa to 3MPa, and
And the ratio Smax / Smin of the maximum breaking strength Smax to the breaking strength Smin in the orthogonal direction with respect to the direction showing the maximum breaking strength is 1.5 to 6. The resin foamed article according to claim 1, The method according to claim 1,
The breaking elongation SSmax in the direction showing the maximum breaking strength is 200% or less,
The rupture elongation SSmax in the direction showing the maximum breaking strength and the rupture extension SSmax / SSmin of the breaking elongation SSmin in the orthogonal direction with respect to the direction showing the maximum breaking strength are 1.5 to 6. 3. The method according to claim 1 or 2,
The ratio Cmax / Cmin of the bubble size Cmax in the direction indicating the maximum breaking strength and the bubble size Cmin in the direction perpendicular to the direction indicating the maximum breaking strength is 1.2 to 5. 4. The method according to any one of claims 1 to 3,
A resin foam having an apparent density of 0.01 to 0.2 g / cm < 3 >. 5. The method according to any one of claims 1 to 4,
A thermoplastic resin foam obtained by decompression treatment of a thermoplastic resin composition impregnated with a high-pressure gas. 6. The method of claim 5,
Wherein the gas is an inert gas. The method according to claim 6,
Wherein the inert gas is carbon dioxide or nitrogen. 8. The method according to any one of claims 5 to 7,
Wherein the gas is a gas in a supercritical state. A foamed seal material comprising the resin foam according to any one of claims 1 to 8. 10. The method of claim 9,
And a pressure-sensitive adhesive layer disposed on one side or both sides of the foam. 11. The method of claim 10,
Wherein the adhesive layer is disposed on the surface of the resin foam through the film layer.

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