JP2010047709A - Elastic sealing material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin elastic sealing material that has a lightweight and high impact resilience and a method for producing the same. <P>SOLUTION: The elastic sealing material includes a polyolefin-based foamed molded article having a large number of linear air holes inside, a hysteresis loss of ≤22% and an impact resilience of ≤60%. The method for producing the same includes: a foamable polyolefin-based thermoplastic resin composition preparation process for preparing a foamable polyolefin-based thermoplastic resin composition (E) made of a polyolefin-based thermoplastic resin component (A), a fibrous water-soluble polymer (B) dispersed into the component (A), a peroxide crosslinking agent component (C) and a blowing agent (D); a foamed molded article molding process for foaming and molding the foamable polyolefin-based thermoplastic resin composition (E) into a desired sealing material shape to give a foamed molded article (F); and a fibrous water-soluble polymer removing process for partially or compactly removing the fibrous water-soluble polymer (B) inside the foamed molded article (F) to form a large number of the linear air holes inside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an elastic sealing material that is suitable for waterproofing, dustproofing, vibration damping, soundproofing, etc. used between parts such as precision equipment and automobiles, and a method for producing the same. Specifically, the present invention relates to various industrial parts such as toner cartridges and ink tank outlets and joints around printers such as laser printers and inkjet printers, joints between automobile air conditioners and vehicle bodies, and joints between automobile tail lamps and vehicle bodies. The present invention relates to an elastic sealing material excellent in flexibility and rebound resilience, which is suitable for realizing sealing properties such as waterproofness, moisture resistance, dustproof property, vibration damping property, and soundproofing property of a connected portion, and a method for producing the same.

  Conventionally, a general-purpose flexible polyurethane foam has been widely used for sealing the connection parts of the various industrial parts. This general-purpose urethane foam is composed mainly of, for example, a polyol component using a polyether polyol alone or in combination with an unsaturated monomer polymerization polyol (hereinafter sometimes referred to as a polymer polyol) and a polyisocyanate component. A foaming agent, a catalyst, and a foam stabilizer are added to the above and foamed to a desired sealing material shape and thickness. The elastic sealing material made of general-purpose polyurethane foam thus obtained is a lightweight sealing material having a relatively low foam density.

  For example, the above-mentioned general-purpose polyurethane foam used in a sealing part of an automobile air conditioner seam, a seal part of a tail lamp and a car body, etc. is lightweight but has low impact resilience. Therefore, the thickness is relatively increased to ensure elasticity during compression. However, by compressing a thick elastic sealing material at a high compression rate, the density of the elastic sealing material at the time of compression increases, and the rigidity increases accordingly. When the rigidity of the sealing material is increased, various vibrations are easily transmitted through the seam sealing material. The vibration propagated and dispersed through the sealing material is converted into sound on the surface of each component connected through the sealing material. This sound propagates inside and outside the vehicle. Since this sound is perceived as an annoying sound in the audible sound region, that is, noise, it is required to be suppressed.

  In order to suppress the propagation of the vibration, a sealing material that can obtain a predetermined rebound resilience is required even when the thickness is reduced and the compressibility is reduced. There is a conflict with density, and if the density is reduced, the resilience is low, so the thickness must be made relatively thick and compressed.

  On the other hand, when a highly elastic urethane foam as described in Patent Document 1 is used, a predetermined resilience can be obtained even if the thickness is reduced and the compression rate during use is reduced. Problems arise due to its high hardness. That is, when the hardness of the sealing material itself is high, vibration is easily propagated because the hardness is high even if the compression rate during use is low. Therefore, even in a sealing material using a highly elastic urethane foam, desired vibration damping characteristics cannot be obtained.

JP 2001-526723 A

  The present invention has been made in view of the above-mentioned conventional problems, and its problem is to provide an elastic sealing material having good vibration damping and soundproofing properties as well as waterproofness, moisture permeability resistance and dustproofness, and a method for producing the same. It is to provide.

  The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, if an elastic sealing material is formed using a foamed molded article that is lightweight and satisfies both rebound resilience and density reduction, it is waterproof and moisture-proof. It was concluded that an elastic sealing material having good dust resistance and at the same time excellent vibration damping and soundproofing properties can be obtained.

  In order to realize a foamed molded product that is lightweight and satisfies both impact resilience and density reduction, further investigations have been made. A polyolefin-based foamed molded product having a large number of linear ventilation holes inside has the desired characteristics. I came to know.

  This polyolefin-based foam molded article is obtained by (i) dispersing a fibrous water-soluble polymer having a specific size in a polyolefin-based resin composition, foam-molding it, and (ii) washing the resulting foam-molded article with water. It can be obtained by removing the fibrous water-soluble polymer by, for example. The obtained foamed molded article has a large number of linear air holes therein, and has a characteristic that hysteresis loss is 22% or less and impact resilience is 60% or less.

The present invention has been made based on the above findings.
That is, the elastic sealing material according to the present invention is characterized by comprising a polyolefin-based foamed molded article having a number of linear air holes therein, a hysteresis loss of 22% or less, and a rebound resilience of 60% or less. To do.

In addition, the method for producing an elastic sealing material according to the present invention is an elastic material comprising a polyolefin-based foamed molded article having a large number of linear air holes therein, a hysteresis loss of 22% or less, and a rebound resilience of 60% or less. A method for producing an elastic sealing material to obtain a sealing material,
A polyolefin-based thermoplastic resin component (A), a fibrous water-soluble polymer (B) dispersed in the polyolefin-based thermoplastic resin component (A), a peroxide crosslinking agent component (C), a foaming agent ( D) and a foamable polyolefin-based thermoplastic resin composition preparation step for preparing a foamable polyolefin-based thermoplastic resin composition (E),
A foam molded body molding step of foaming the foamable polyolefin-based thermoplastic resin composition (E) into a desired sealing material shape to obtain a foam molded body (F);
The foamed molded product (F) is brought into contact with moisture, and the fibrous water-soluble polymer (B) inside is partially or completely removed to form the fibrous water-soluble water that forms the plurality of linear air holes therein. A functional polymer removal step;
It is characterized by having.

  The said sealing material shape means the various shapes currently used for the usual sealing material. That is, there are various shapes such as an O-ring shape, a band shape, a sheet shape, a dish shape, etc., and the cross-sectional shape is also a circular shape, a rectangular shape, an elliptical shape, an oval shape, a trapezoidal shape, a polygonal shape, and combinations thereof An indefinite shape made up of is included.

  The said structure WHEREIN: It is preferable that the diameter dimension of the said linear ventilation hole is 0.1 micrometer or more and 20 micrometers or less.

Moreover, it is preferable that 25% hardness (ILD) of the elastic sealing material of this invention is 170-260 N / 314cm < ² >, and air permeability is 10-60 L / min.

  In the elastic sealing material of the present invention, the average diameter of the linear ventilation holes formed inside the polyolefin-based foam molded article is preferably 20 μm or less as described above, and the lower limit is preferably 0.1 μm or more. . In order to make the average diameter of the linear air holes 0.1 μm to 20 μm, the fineness of the fibrous water-soluble polymer (B) dispersed in the foamable polyolefin-based thermoplastic resin composition (E) is set to be about However, it may be adjusted to 1.0 dtex to 15.0 dtex.

  The said structure WHEREIN: It is preferable that the compounding quantity of the said fibrous water-soluble polymer (B) is 2-50 weight part with respect to 100 weight part of said foamable polyolefin-type thermoplastic resin compositions (E), 5 More preferably, it is set to -30 parts by weight. By setting within these ranges, it becomes possible to more stably disperse and form linear air holes.

  In the present invention, a large amount of fibrous polyvinyl alcohol (B) dispersed in the polyolefin-based thermoplastic resin component (A) is partially or completely dissolved and removed in the interior of the polyolefin-based foamed molding as a base material. A linear vent is formed.

  Therefore, even when a general-purpose high-foaming foam or a high-foaming foam with high resilience and high foam skeleton strength is used as the base polyolefin foamed foam, the breathability is high. Is excellent in elasticity, is flexible, and an elastic sealing material made of a lightweight foam-molded article having a density lower than that of a conventional high-elasticity foam is obtained. Furthermore, the flow of air between the bubbles inside the elastic seal material when the vibration acts on the elastic seal material is facilitated by the large number of linear vents formed inside the base material. For this reason, the damping performance at the time of vibration transmission is moderately improved, and the vibration absorption is further improved. The improvement of the vibration damping property when such vibration is applied can be confirmed by the stress with respect to the compressibility. The preferable range of the stress with respect to the compressibility is realized when the hysteresis loss (JIS E7104) is 20% or less and the impact resilience (JIS K6400-3) is 60% or less.

  The elastic sealing material according to the present invention includes a polyolefin-based thermoplastic resin component (A), a fibrous water-soluble polymer (B) dispersed in the polyolefin thermoplastic resin component (A), and a peroxide crosslinking agent component. (C) and a foamable polyolefin-based thermoplastic resin composition (E) containing a foaming agent (D) can be used. Hereinafter, each component will be described.

(Polyolefin-based thermoplastic resin component (A))
Examples of the polyolefin-based thermoplastic resin component (A) in which the fibrous water-soluble polymer (B) is dispersed include the fibrous water-soluble polymer (B) contained in a dispersion medium such as water or an organic solvent and a high molecular weight. A product obtained by removing the dispersion medium from a mixture of the polyolefin-based thermoplastic resin component (A) is used.

The polyolefin-based thermoplastic resin component (A) is not particularly limited, and any type that is usually used when producing a highly elastic polyolefin-based foam or a general-purpose polyolefin-based foam can be used. Examples thereof include general-purpose polymers such as polyethylene and polypropylene, rubbers such as ethylene propylene diene monomer (EPDM), and thermoplastic elastomers such as polyolefins and polystyrenes.
As the polyolefin-based thermoplastic resin component (A) of the present invention, a mixture of two or more polyolefin materials may be used. Examples of such combinations include combinations of polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) and the like.

(Fibrous water-soluble polymer (B))
Fibrous polyvinyl alcohol, denp amylose, amylopectin, protein gelatin, silk (fibroin), casein, fibrous polysaccharide-based bullulan, guar gum degradation Products, soybean polysaccharide, agar, cellulose, arabinoxylan, sodium alginate, carrageenan, pectin and the like.

  The “fibrous water-soluble polymer” as used in the present invention is not only in the form of a fiber and can be adjusted to a suitable fineness by being beaten when dispersed in a polyol. In addition, when dispersed in the polyolefin-based thermoplastic resin component (A) or when stirring and foaming with the peroxide cross-linking agent component (C) or other components, further shearing is applied to fibrillate. Also included are those that can be (small fiberized) and can be present as fibrous fibers of suitable fineness in the foamable polyolefin-based thermoplastic resin composition (E) after preparation.

  As a commercial item of fibrous polyvinyl alcohol which is a kind of the above-mentioned fibrous water-soluble polymer (B), “Kuraron” manufactured by Kuraray Co., Ltd. may be mentioned. This fibrous water-soluble polymer (B) is easily soluble in water at various temperatures and conditions, such as water from low temperature to boiling water or water vapor, and a brand having a desired dissolution temperature is selected. And can be used.

  When the fine fiber-like water-soluble polymer (B) is dispersed in the foamable polyolefin-based thermoplastic resin composition (E), the fineness (thickness) is usually 1.0 to 15.0 dtex. It is preferable. Moreover, the average length of this fine fibrous water-soluble polymer (B) is 1.0 mm-100 mm normally, Preferably it is 1.0-50 mm. When the fineness and average length of the fine fiber-like water-soluble polymer (B) dispersed in the foamable polyolefin-based thermoplastic resin composition (E) are within the above range, the assembled elastic seal material has an assembly load. The compression resistance inside the elastic sealing material when acting can be within a suitable range. The diameter of the linear vent that provides such good compressibility is in a range corresponding to 0.1 μm to 20 μm.

  As is well known, the thickness of a fiber (yarn) is determined from the relationship between length and weight, but since the cross section of the fiber is not circular, the thickness cannot be expressed by the diameter. The thickness is expressed in relation to “mass”. The display method includes a “constant length display method” based on the length and a “constant length display method” based on the weight. In the present invention, the display method is a kind of the former constant length display method. The thickness of the fibrous water-soluble polymer (B) is defined by detex (dtex).

Decitex (dtex) is a constant length type thickness display method that is commonly used for all single fibers, yarns, and fiber bundles. For a yarn length of 10,000 m, 1 g of yarn weight is indicated as 1 dtex. To do.
That is, the unit of fineness (dtex) used in the present invention is represented by the following formula when the length of the yarn is represented by L (m) and the weight of the yarn is represented by W (g).
dtex (tex) = 10000 × W (g) / L (m)

  As described above, the fineness of the fibrous water-soluble polymer (B) used in the present invention when dispersed in the expandable polyolefin-based thermoplastic resin composition (E) is 1.0-15.0 dtex (dtex). ), The fibrous water-soluble polymer (B) is controlled by appropriately controlling the shearing force when the fibrous water-soluble polymer (B) is kneaded and dispersed in the polyolefin-based thermoplastic resin component (A). To fibrillate (fibrillate).

  The blending amount of the fibrous water-soluble polymer (B) is 2 to 50 parts by weight, further 5 to 30 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition (E). In order to stably disperse and form the linear vent holes, it is preferable.

  When the fibrous water-soluble polymer (B) is dispersed in the polyolefin-based thermoplastic resin component (A), direct kneading and dispersion are preferred, but water can be used as the other dispersion medium. Hydrophilic organic solvents such as divalent alcohols can also be used.

  The boiling point of the polyolefin-based thermoplastic resin component (A) is sufficiently higher than the organic solvent that is the dispersion medium of the fibrous water-soluble polymer (B), so that the fibrous water-soluble polymer (B ) Is an organic solvent, the organic solvent can be removed from the mixture of the polyolefin-based thermoplastic resin component (A) and the fibrous water-soluble polymer (B) by distillation.

  When the dispersion medium of the fibrous water-soluble polymer (B) is water, the dispersion master of the fibrous water-soluble polymer having high dispersion stability is obtained by dehydrating the distillation at a low temperature and, if necessary, under reduced pressure. A batch is obtained.

  In the case where a mixture of several polyolefin-based thermoplastic resin components is used as the polyolefin-based thermoplastic resin component (A), the fibrous water-soluble polymer (B) is converted into a polyolefin-based thermoplastic as described above. A master batch of a fibrous water-soluble polymer-dispersed polyolefin thermoplastic resin component is prepared by dispersing in the resin component (A), and this polyolefin water-soluble polymer-dispersed polyolefin thermoplastic resin component is mixed with other polyolefin-based thermoplastics. Used in combination with resin components.

(Peroxide crosslinking agent component (C))
The peroxide crosslinking agent component (C) is not particularly limited, and specific examples that can be preferably used include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (tert- Butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) ) -3,3,3-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4 dichlorobenzoyl peroxide, tert-butylperoxy Benzoate, tert-butyl perbenzoate, tert-butyl peroxyisopropyl carbonate, Acetyl peroxide, lauroyl peroxide, etc. tert- butyl cumyl peroxide.

  Among these, in terms of odor and scorch stability, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) ) Hexin-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-bryl-4,4-bis (tert -Butylperoxy) valerate is preferred, and 1,3-bis (tert-butylperoxyisopropyl) benzene is most preferred.

  The peroxide crosslinking agent component (C) is usually preferably blended in an amount of about 0.05 to 2.5 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition (E).

In the present invention, sulfur, p-quinonedioxime, p, p′-benzoylquinonedioxime, N-methyl-is used as an auxiliary in the branching and partial crosslinking treatment with the peroxide crosslinking agent component (C). Peroxy crosslinking aids such as N-4-dinitrosoaniline, nitrosobenzene, diphenylguanidine, trimethylolpropane N, N′-m-phenylenedimaleimide, or divinylbenzene, triallyl cyanurate, ethylene glycol dimethacrylate, Polyfunctional methacrylate monomers such as trimethylolpropane trimethacrylate and acrylic methacrylate, and polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate can be blended.
The flowability and foamability of the foamable polyolefin-based thermoplastic resin composition (E) at the time of injection can be appropriately adjusted depending on the blending amount of these auxiliaries.

  When partial cross-linking is performed by irradiation with ionizing radiation such as electron beam, neutron beam, α-ray, β-ray, γ-ray, X-ray, ultraviolet ray, etc., it is not necessary to add a cross-linking agent. As branching and partial cross-linking treatment, auxiliary agents include divinylbenzene, triallyl cyanurate, ethylene glycol dimethacrylate, trimethylpropane trimethacrylate, polyfunctional methacrylate monomers such as acrylic methacrylate, vinyl butyrate, vinyl stearate Such a polyfunctional vinyl monomer can be blended.

(Foaming agent (D))
As the foaming agent (D) blended in the polyolefin-based thermoplastic resin composition (E) described above, there is a pyrolytic foaming agent that generates gas upon thermal decomposition. Specifically, azodicarbonamide ( ADCA), diethyl azocarboxylate, azodicarbonamide, barium azodicarboxylate, 4,4-oxybis (benzenesulfonylhydrazide), 3,3-disulfonehydraside phenylsulfonic acid, N, N′-dinitrosopentatetramine, Examples thereof include organic blowing agents such as p-toluenesulfonyl hydrazide and trihydrazinotriazine, and inorganic blowing agents such as sodium hydrogen carbonate, ammonium hydrogen carbonate and ammonium carbonate.

  In particular, azodicarbonamide (ADCA), N, N'-dinitrosopentatetramine, and trihydrazinotriazine are preferable as the organic foaming agent, and sodium hydrogen carbonate is preferable as the inorganic foaming agent. Further, sodium hydrogen carbonate, monosodium citrate and glycerin fatty acid ester may be mixed and used.

By selecting these foaming agents, the decomposition peak temperature of the foaming agent is selected so that the decomposition peak temperature is higher than the decomposition peak temperature of the organic oxide used in combination.
These foaming agents can be used alone or in combination of two or more, or a so-called decomposition aid.
In addition, additives such as foaming aids, wetting agents, weathering stabilizers, heat stabilizers, anti-aging agents, colorants, and fillers are blended at any stage of the kneading.

(Other ingredients)
In addition to the above components (A), (B), (C) and (D), the foamable polyolefin-based thermoplastic resin composition for obtaining the elastic sealing material of the present invention can be used in accordance with conventional crosslinking as required. You may mix | blend other components, such as an agent, various catalysts, and a foam stabilizer.

  As the cross-linking agent, diethanolamine, polyoxyethylenetetraol, or the like can be used.

  The catalyst is not particularly limited, and various conventional catalysts used for producing polyurethane can be used. For example, triethylenediamine, bis- (2-dimethylaminoethyl) ether, triethylamine, N-methylmorpholine, N-ethylmorpholine, tripropylamine, tributylamine, dimethylbenzylamine, N, N, N ′, N ″ — Pentamethyldiethyleneamine, 1,8-diaza-bicyclo (5,4,0) undecene-7,1,2-dimethylimidazole, 1-butyl-2-methylimidazole, N, N-dimethyl-N-hexanolamine, Examples include dimethylethanolamine, amines such as N-reserved ethylene-N, N-dimethylamine; or organic acid salts thereof; and organic metals such as stannous octoate, dibutyltin dilaurate, and zinc naphthalate.

  As the foam stabilizer, an alkylene polyether-modified silicon surfactant is used. A fluorine-based surfactant can also be used.

(Method for producing elastic sealing material)
The elastic sealing material of the present invention was obtained by preparing a foamable polyolefin-based thermoplastic resin composition (E) by appropriately combining the main raw materials of the components (A) to (D) described above and other components. The foamable polyolefin-based thermoplastic resin composition (E) was foam-molded into a desired sheet material shape to obtain a sheet-material-shaped foam molded body (F) (sheet material shape foam molded body molding step), and obtained. The foamed molded body (F) in the form of a sheet material is brought into contact with moisture, and the fibrous water-soluble polymer (B) inside is partially or completely removed to form the numerous linear vent holes inside. (Fibrous water-soluble polymer removal step) can be obtained.

  The foamable polyolefin-based thermoplastic resin composition (E) is kneaded and then foamed to obtain a foamed molded product. The kneading is divided into several times or performed stepwise to finally obtain an unfoamed foamable thermoplastic resin composition (E).

  As a kneading means, a known kneading machine such as a V-shaped brabender, a tumble brabender, a ribbon brabender, a Henschel brabender, a Banbury mixer, a mixing roll, a kneader, an extruder, or the like may be used. it can.

  The foamable polyolefin-based thermoplastic resin composition (E) may be partially crosslinked by applying heat during kneading (dynamic crosslinking), or kneaded in an uncrosslinked state without applying temperature. The resulting kneaded product may be partially crosslinked by applying heat (static crosslinking). In either case, the crosslinking temperature is set to a temperature not higher than the foaming temperature of the foaming agent (D) contained in the foamable polyolefin-based thermoplastic resin composition (E). In addition, the kneaded material before shaping | molding is good also as a substantially uncrosslinked state, without carrying out partial bridge | crosslinking. Whether to be in a partially crosslinked state or in an uncrosslinked state is appropriately selected depending on the operability during molding.

  Next, the kneaded product is molded into a desired sealing material shape, and the resulting molded product is subjected to a temperature equal to or higher than the foaming temperature to obtain a foamed molded product. The uncrosslinked portion in the unfoamed molded body is crosslinked by the foaming temperature at this time, and the entire foamed molded body is completely crosslinked.

  Foaming of the kneaded product can be done by hot air circulation furnace, infrared heating, high frequency heating, normal pressure foaming method by heating on salt bath, pressure foaming method by heating press, injection foaming in extrusion mold, extrusion foaming, etc. Can be realized.

  In addition, it can replace with foaming by a thermal decomposition type foaming agent, and can also foam resin by vapor pressures, such as a volatile solvent and water. In this case, a foamable polyolefin-based thermoplastic resin composition (E) that does not knead the pyrolytic foaming agent is once prepared, and carbon dioxide gas, nitrogen gas, water vapor is used as the foaming agent (D) in this resin composition (E). The gas generating component for foaming the resin is dispersed or impregnated by a gas pressure such as a volatile solvent. By heating the resin composition (E) mixed with a foaming agent (D) such as a volatile solvent or water, gas is generated in the resin composition (E), thereby obtaining a foam molded article. The gas generating component is mixed into the resin composition (E) immediately before taking out the foamable polyolefin-based thermoplastic resin composition (E) from the molding machine at the time of injection molding, stamping molding, or extrusion molding. It is preferable.

  In the fibrous water-soluble polymer removing step, the foamed molded product (F) formed into a sheet material shape is contacted (immersed or exposed) with water selected from water, warm water, boiling water, or water vapor, or The whole is dissolved and removed. By this fibrous water-soluble polymer removing step, an elastic sealing material excellent in air permeability and flexibility can be obtained.

  Examples of the elastic sealing material and the manufacturing method thereof according to the present invention will be described below. The following examples are preferred examples for explaining the present invention, and do not limit the present invention.

Example 1
Fibrous polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade names “Claron K-II, EQ5-R”; fineness of 2.0 dtex, average length of 4.0 mm) is used as the fibrous water-soluble polymer, and polyolefin-based As a thermoplastic resin component, a kneaded product of polypropylene and ethylene propylene diene terpolymer was used. Fibrous polyvinyl alcohol was dispersed in a polyolefin-based thermoplastic resin component. The blending amount of the fibrous polyvinyl alcohol is 14.7 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition (15.0 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition. Part by weight.

  For 50 parts by weight of the fibrous polyvinyl alcohol-dispersed polyol, 50 parts by weight of polymer polyol, 10.0 parts by weight of azodicarbonamide as a foaming agent, 1.0 part by weight of foam stabilizer, and 0.4 parts by weight of crosslinking agent Were blended and kneaded to obtain a foamable polyolefin-based thermoplastic resin composition.

  Next, a test piece of a polyolefin-based foamed molded article having a length of 500 mm, a width of 500 mm, and a thickness of 75 mm was foam-molded using the foamable polyolefin-based thermoplastic resin composition having the above composition.

  Subsequently, the foamed molded body of the test piece was immersed in hot water at 70 ° C., and the internal fibrous polyvinyl alcohol was completely dissolved and removed to obtain a sample (S1) of an elastic sealing material.

(Example 2)
In Example 1 above, the same product (made by Kuraray Co., Ltd., trade names “Kuraron K-II, EQ5-R”) was used as the fibrous polyvinyl alcohol, but the shear force when dispersed in the polyolefin-based thermoplastic resin component A sample (S2) of an elastic sealing material was obtained in the same manner as in Example 1 except that the control was made lower than that in Example 1.

(Example 3)
In Example 1, the fibrous polyvinyl alcohol was blended so as to be 30 parts by weight with respect to 100 parts by weight of the polyolefin-based thermoplastic resin composition, and the shearing force when dispersed in the polyolefin-based thermoplastic resin was determined in Example 2. A sample (S3) of an elastic sealing material was obtained in the same manner as in Example 2 except that the control was lower.

(Comparative Example 1)
A general-purpose molded urethane foam was produced in the same size as in Example 1 with the formulation shown below (Sample C1).
The blending composition is 70 parts by weight of polyether polyol, 30 parts by weight of polymer polyol, 4.0 parts by weight of water as a foaming agent, 5.0 parts by weight of hydrofluoroether “HFE-254pc”, and 1.0 part by weight of foam stabilizer. As a catalyst, 0.28 part of a diethylenediamine dilute solution (33%), 0.06 part by weight of dibutyltin diurarate, and 100 parts by weight of tolylene diisocyanate “(T-80) INDEX100” were used.

(Comparative Example 2)
A high-elasticity mold foam developed for the purpose of improving vibration absorption was produced in the same size as in Example 1 using the formulation shown below (Sample C2).
The blending composition was 50 parts by weight of polyether polyol, 50 parts by weight of polymer polyol, 2.8 parts by weight of water as a foaming agent, 1.0 part by weight of a foam stabilizer, and 0.4% of a diluted triethyldiamine solution (33%) as a catalyst. Parts by weight and 0.3 parts by weight of tetrahexamethylene diain and 105 parts by weight of diphenylmethane diisocyanate / tolylene diisocyanate “(= 20/80) INDEX105”.

(Comparative Example 3)
In Example 1 above, a sample (C3) of an elastic sealing material is obtained in the same manner as in Example 1 except that the fibrous polyvinyl alcohol is blended so as to be 1 part by weight with respect to 100 parts by weight of the polyurethane composition. It was.

(Comparative Example 4)
In Example 1 above, a sample (C4) of an elastic sealing material was obtained in the same manner as in Example 1 except that the fibrous polyvinyl alcohol was blended in an amount of 51 parts by weight with respect to 100 parts by weight of the polyurethane composition. It was.

(Evaluation)
For samples S1 to S3 obtained in Examples 1 to 3 and Samples C1 to C4 obtained in Comparative Examples 1 to 4, foam density (kg / m ³ ), 25% hardness (ILD) ( N / 314 cm ² ), impact resilience (%), hysteresis loss (%), air permeability (L / min), and linear air hole diameter (μm).

The compliant standard (JIS standard) and method of each evaluation test are as follows.
(Foam density)
Each foamed molded body sample was cut into dimensions of 100 mm in length and width, and 50 mm in height, excluding the skin portion, and the weight was measured for the cut sample, and the obtained weight was divided by the volume.

(25% hardness (ILD))
It measured based on JIS K6400-2.

(Rebound resilience)
The skin portion was removed from each foamed molded product sample, and the cut sample was cut into dimensions of 100 mm in length and width and 50 mm in height, and the cut sample was measured according to JIS K6400-3.

(Hysteresis loss)
The skin part was removed from each foamed molded body sample, and cut into dimensions of 100 mm in length and width and 50 mm in height. The cut out sample was subjected to hysteresis loss in accordance with JIS E7104.

(Breathable)
The skin part was removed from each foamed molded body sample, cut into dimensions of 100 mm in length and width, and 50 mm in height, and this cut sample was determined by measuring in accordance with JIS K6400-7.

(Measurement of vibration transmissibility)
A sample with a 0.5 kgf weight is fixed to the surface of the vibrator plate with an adhesive, and vibrations are applied to the top and bottom of the sample. The transmission rate was detected. The vibration transmission rate of the peak top that appeared between 1 (Hz) and 100 (Hz) was read.

(Measurement of diameter of linear vent)
The diameter dimension of the cell formed by the air bubbles in the foam molded article is generally 100 μm to 500 μm, and hardly becomes 50 μm or less. On the other hand, when the fibrous water-soluble polymer is beaten most strongly and the fineness becomes the smallest, the diameter dimension of the linear air holes formed by dissolving and removing the fibrous water-soluble polymer having the small fineness is 0. It can be as small as 01 μm. In addition, when the fibrous water-soluble polymer is blended in a large amount and agglomerates to form a bundle, the diameter of the linear vent formed by dissolving and removing the bundle of water-soluble polymer is It can be as large as 50 μm.

Thus, the upper limit value of the diameter of the linear vent is about 50 μm, and the lower limit value of the cell diameter due to the bubbles is about 100 μm. That is, the range of the diameter dimension of the linear ventilation holes formed in the foam molded body can be known by observing the range in which the size of the holes appearing in the cross section of the foam molded body is 50 μm or less.
Therefore, the diameter dimension of the linear ventilation holes of the foamed molded body samples of this example and the comparative example was measured as follows.

  A skin portion is removed from each polyolefin foam molded body sample, and the foamed direction is cut out into dimensions of 100 mm in length and width and 50 mm in height so as to coincide with the vertical direction. Sliced perpendicularly to the foaming direction so that it passes through the center of this cut sample (number of samples is 5), observe the cross section of the slice with a scanning electron microscope, and confirm the diameter of the linear vent did. As a confirmation method, based on the magnification of a scanning electron microscope capable of observing the air holes appearing in the slice cross section on the field of view, the existing air holes are 0.01 to 0.1 μm in diameter, 0.1 A method of classifying into diameter groups of 10 μm diameter, 10-20 μm diameter, 20-30 μm diameter, 30-40 μm diameter, 40-50 μm diameter, 50 μm diameter or more was used. That is, for each diameter of 10-20 μm diameter, 20-30 μm diameter, 30-40 μm diameter, 40-50 μm diameter, 50 μm diameter or more, the presence / absence of existence in a 100 μm square at an arbitrary magnification of about 1300 times Observe the presence or absence in the 30 μm square for any 5 samples at a magnification of about 3000 times for the 0.1 to 10 μm diameter, and about 10,000 times for the 0.01 to 0.1 μm diameter. The presence / absence of presence in a 10 μm square was observed for any five samples at a magnification, and the existence range of the diameter dimension of the linear vent was determined from the results.

  The lower the hysteresis loss and air permeability, the higher the elasticity of the elastic sealing material. The smaller the impact resilience, the lower the subsidence speed during assembly, and the sheet material is compressed more slowly.

  The evaluation results are shown in the following (Table 1: Examples 1 to 3) and (Table 2: Comparative Examples 1 to 4).

  In the above (Table 1) and (Table 2), the impact resilience and air permeability are values at the core portion of the elastic sealing material.

  As can be seen from (Table 1), the general-purpose foam of Comparative Example 1 is an elastic sealing material having a low impact resilience and a difficulty in vibration transmission rate, and Comparative Example 2 has a high foam density and impact resilience, and vibration. Since the evaluation of the transmission rate is extremely bad, it is inferior in silence.

  On the other hand, Example 1 is extremely excellent in breathability and is an elastic sealing material having a considerably high rebound resilience, so that even if the thickness is thin, it can be firmly adhered to both interfaces such as joints, Dust and waterproof seals can be taken, and at the same time, the vibration transmission rate is low, so it is very quiet.

  The elastic sealing material of the example has a hysteresis loss (%) of 22% or less. In contrast, the elastic sealing material of the comparative example has a hysteresis loss (%) of 22% or more. That is, the hysteresis loss of the elastic sealing material of the example is lower than that of the elastic sealing material of the comparative example. As described above, the lower the hysteresis loss, the higher the elasticity of the elastic sealing material. Therefore, the elastic sealing material of an Example has high elasticity compared with the elastic sealing material of a comparative example.

  The elastic sealing material of the example has a rebound resilience (%) of 47 to 55, whereas the elastic sealing material of the comparative example has a rebound resilience (%) of 48 to 83. As mentioned earlier, the smaller the rebound resilience, the smaller the follow-up reaction force at the time of compression recovery during vibration in gaps such as joints, and the basic sealing properties such as dustproof and waterproofing tend to be poor, and the elastic sealing material When the thickness is increased and packed, the basic sealing performance tends to be improved, but the vibration transmission rate is large and the quietness is poor. Therefore, the elastic sealing material of the example can obtain a sealing characteristic that is excellent in noise at the same time as the basic seal as compared with the elastic sealing material of the comparative example.

  Although the elastic sealing material obtained in Comparative Example 4 has a low rebound resilience, the reason why the vibration transmission rate during sealing is poor is considered to be as follows. That is, in the composition of the elastic sealing material of Comparative Example 4, the amount of fibrous polyvinyl alcohol is 51 parts by weight with respect to 100 parts by weight of the polyolefin composition. Therefore, the fibers that have been beaten and kneaded and dispersed during foam molding are too close to each other. As a result, after the fibrous water-soluble polymer removal step, there are many single linear vents, but the number of adjacent coalescence increases. Therefore, many open cell holes having a diameter of 5 μm or more are formed, thereby increasing the air permeability and increasing the hysteresis loss, resulting in inferior basic sealability.

  In the elastic sealing material of this example, the reason why the excellent sealing property is obtained is that the fibrous water-soluble polymer is removed from the polyolefin molded body in which an appropriate fibrous water-soluble polymer material (type and amount) is blended. This is because the linear air holes generated in the polyolefin molded body allow many independent foamed portions in the polyolefin molded body to communicate with each other and open to the outside air of the polyolefin molded body. This is because the compressed air inside is gradually released when the sealing material is compressed.

  The elastic sealing material of the present invention creates a polyolefin foam molded product in which a large number of fibrous water-soluble polymers are dispersed inside by blending a fibrous water-soluble polymer in a polyolefin, and a part of the foam molded product is formed from the foam molded product. By removing the fibrous water-soluble polymer properly or completely, it has a large number of linear air holes. The elastic sealing material of the present invention is poor in air permeability, but is expected to have an extremely large number of actual open cell ratios (pores of several microns or less that cannot be detected by the current air permeability measurement) and reduce the compression speed during assembly. It is possible to achieve flexibility while having a high elastic modulus. Moreover, the density of the elastic sealing material of the present invention is smaller than that of the conventional elastic sealing material because the fibrous water-soluble polymer is removed.

  For the above reasons, according to the present invention, while maintaining a high elastic modulus, it is light and flexible, has excellent sealing properties, can be thinned, and is waterproof to be used between parts such as precision equipment and automobiles, It is possible to provide an elastic sealing material that is comprehensively excellent for applications such as dust resistance, vibration control, and soundproofing.

Claims (8)

  An elastic sealing material comprising a polyolefin-based foam molded article having a large number of linear air holes therein, a hysteresis loss of 22% or less, and a rebound resilience of 60% or less.   The elastic sealing material according to claim 1, wherein a diameter of the linear air hole is 0.1 μm or more and 20 μm or less. The elastic sealing material according to claim 1 or 2, wherein 25% hardness (ILD) is 170 to 260 N / 314 cm ² and air permeability is 10 to 60 L / min.   A polyolefin-based thermoplastic resin component (A), a fibrous water-soluble polymer (B) dispersed in the polyolefin-based thermoplastic resin component (A), a peroxide crosslinking agent component (C), a foaming agent ( The foamable polyolefin-based thermoplastic resin composition (E) containing D) is foam-molded into a predetermined sealing material shape, and the fibrous water-soluble polymer in the resulting foam-molded product is partially or completely washed away. The elastic sealing material according to any one of claims 1 to 3, wherein the elastic sealing material is obtained by performing the above.   The blending amount of the fibrous water-soluble polymer (B) is 2 to 50 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition (E). Elastic sealing material. A method for producing an elastic sealing material having a large number of linear air holes therein, obtaining an elastic sealing material comprising a polyolefin-based foamed molded article having a hysteresis loss of 22% or less and a rebound resilience of 60% or less,
A polyolefin-based thermoplastic resin component (A), a fibrous water-soluble polymer (B) dispersed in the polyolefin-based thermoplastic resin component (A), a peroxide crosslinking agent component (C), a foaming agent ( D) and a foamable polyolefin-based thermoplastic resin composition preparation step for preparing a foamable polyolefin-based thermoplastic resin composition (E),
A foam molded body molding step of foaming the foamable polyolefin-based thermoplastic resin composition (E) into a desired sealing material shape to obtain a foam molded body (F);
The foamed molded product (F) is brought into contact with moisture, and the fibrous water-soluble polymer (B) inside is partially or completely removed to form the fibrous water-soluble water that forms the plurality of linear air holes therein. A functional polymer removal step;
The manufacturing method of the elastic sealing material characterized by having.   The method for producing an elastic sealing material according to claim 6, wherein a diameter of the linear vent hole is 0.1 μm or more and 20 μm or less.   The blending amount of the fibrous water-soluble polymer (B) is 2 to 50 parts by weight with respect to 100 parts by weight of the foamable polyolefin-based thermoplastic resin composition (E). The manufacturing method of the elastic sealing material as described in any one of.