JP2009145694A - Sound absorbing substrate for vehicle and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing substrate subjected to perforating without reducing thickness of an interior material for a vehicle in order to produce the sound absorbing substrate making the maximum possible use of the sound absorbing performance inherent to the material while satisfying the practical rigidity as the interior material for the vehicle. <P>SOLUTION: The sound absorbing substrate is constituted by laminating non-permeable skin layers on both surfaces of a permeable sound absorbing layer, and opening non-penetrating holes in the material from either one surface side. Finding is made that the rigidity is high, and the maximum possible use of the sound absorbing performance inherent to the material sound is made possible by opening diameters are 0.5-2.5 mm and pitches are 6-20 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound-absorbing base material used for vehicle interior materials such as a vehicle ceiling, a door, and a luggage box, and a method for manufacturing the same.

  Conventionally, providing a through hole and a bottomed hole in a material has been widely performed as a measure for imparting sound absorbing performance to the material. For example, Patent Document 1 discloses a laminated material in which a plurality of holes are perforated in a sound-absorbing laminated interior material such as an automobile carpet.

  In particular, in order to enhance sound absorption performance, foamed resin materials are widely used, and various products obtained by perforating these materials are known as measures for adding performance.

  For example, Patent Document 2 discloses a plastic foam that is compressed by passing between rolls and simultaneously perforated with a perforating needle.

  Further, Patent Document 3 discloses a method for producing a perforated foamed plastic material, such as cutting with a needle having a needle-like object or rod-like object into a foam material after foam molding, cutting with a drill having a spiral blade, and the like.

  By the way, in order to provide high sound absorption performance, and to maintain or improve the rigidity of the material, the thickness of the material greatly affects. It is extremely important to apply processing.

  However, when the surface pressure applied to the foam during the perforating process is large, such as through compression between rolls having perforating needles, there has been a problem of significantly reducing the material thickness.

On the other hand, when a large number of holes are opened with the surface pressure applied to the foam being reduced, the hole diameter must be reduced. For example, when a hole is opened using a needle, the strength of the needle is small. There has been a problem that the loss frequently occurs and the workability and productivity are greatly reduced.
JP 62-184947 A JP-A-63-151435 JP2003-335893

  In view of the above problems, the present invention does not reduce the thickness of the material in order to produce a sound-absorbing base material that satisfies the practical rigidity as a vehicle interior material and that utilizes the sound-absorbing performance of the material. An object of the present invention is to provide a sound-absorbing base material perforated and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventor,
[1] A sound-absorbing base material in which a non-breathable skin layer is laminated on both surfaces of a breathable sound-absorbing layer, and a non-through hole reaching the breathable sound-absorbing layer from the surface side of any one of the non-breathable skin layers is provided. A non-through hole having an opening diameter of 0.5 to 2.5 mm and a pitch of 6 to 20 mm,
[2] The sound-absorbing substrate according to [1], wherein the sound-absorbing layer comprises an open-cell foamed sheet,
[3] The sound-absorbing substrate according to [1] or [2], wherein the sound-absorbing layer comprises an open-cell foamed sheet made of a modified polyphenylene ether-based resin,
[4] A method for producing a sound-absorbing base material comprising a non-breathable skin layer laminated on both surfaces of a breathable sound-absorbing layer, and a non-penetrating hole provided from the surface side of any one of the non-breathable skin layers. In addition, after laminating a non-breathable skin layer on a breathable sound absorbing layer, a needle having a pitch of 6 to 20 mm is pressed against a roll disposed on the peripheral surface to provide a non-through hole, [1] to [ 3] The method for producing a sound-absorbing substrate according to any one of [3]

  The sound-absorbing base material obtained by the present invention is perforated without reducing the thickness of the material, and thus has high sound-absorbing performance while maintaining appropriate rigidity for practical characteristics, and is a vehicle interior material. It is effective as a building material.

  The sound-absorbing substrate in the present invention is a laminated substrate obtained by laminating a non-breathable skin layer on both sides of the breathable sound-absorbing layer, and further reaches the breathable sound-absorbing layer from the surface of any one of the non-breathable skin layers. The structure has a non-through hole. The non-through holes are preferably opened under conditions of an opening diameter of 0.5 mm to 2.5 mm and a pitch of 6 to 20 mm. Since the thickness of the sound-absorbing substrate is not substantially reduced by drilling under such conditions, the sound-absorbing substrate of the present invention has practical characteristics even when the center of the substrate is a breathable layer. It has satisfactory rigidity.

  The breathable sound absorbing layer in the present invention may be any material known to those skilled in the art as long as it has both breathability and sound absorbing properties. In general, examples of the breathable material include fiber materials, composite materials of fibers and resins that fix the fibers, and foam materials. Examples of the fibers include inorganic fiber materials typified by glass fibers and glass wool, and fiber materials made of organic fibers such as polyethylene terephthalate, polypropylene, and polyethylene. There is also a material made of ultrafine fibers as a high sound-absorbing fiber material using these. Examples of the foam material include an open-cell foam represented by polyurethane and the like, and a bead foam imparted with sound absorption by providing a gap.

  Among these, for example, when used for an interior material for a vehicle, a foam material is preferable as a lightweight and rigid material. Furthermore, it is more preferable to use an open-cell foam from the viewpoint of imparting high sound absorption.

  When an open cell foam is used as the breathable sound absorbing layer in the present invention, the foaming method, the foamed resin type, and the foaming agent type are not particularly limited. Further, the open cell ratio is not necessarily uniform. For example, the surface layer may have a structure such as a closed cell layer, and the inside may have a structure such as an open cell layer. Further, the foam may be subjected to mechanical perforation or non-perforation by post-processing to improve sound absorption.

  As a foaming method for producing an open-cell foam, for example, a kneaded product obtained by melt-kneading the resin and the foaming agent at a temperature not lower than the melting point of the base resin and not higher than the decomposition temperature of the foaming agent, Normal pressure foaming method in which foaming agent is heated to a temperature equal to or higher than the decomposition temperature of the foaming agent and foamed at normal pressure; the base resin containing the foaming agent is extruded from the die in the molten state, so that the pressure on the melt is increased from the high pressure state to the normal pressure. An extrusion foaming method in which the foaming agent is changed to foaming; filling a base resin containing a foaming agent into a closed mold, heating under pressure to decompose the foaming agent, and then releasing the pressure to change the resin Pressure foaming method that rapidly expands; Injection foaming method that uses an injection molding method to form a uniformly foamed core layer and a non-foamed skin layer; a finely divided polymer containing an evaporating foaming agent is desired Filled in mold and temperature above boiling point of blowing agent And mold foaming method the polymer to produce a porous molded body is heated to a temperature which softens; mold bead foaming method using foamed beads, and the like.

  Examples of foamed resin types for producing open-cell foams are thermosetting resins such as phenol resin, epoxy resin, melamine resin, urea resin (urea resin), unsaturated polyester resin, alkyd resin, polyurethane, and thermosetting polyimide. Examples of the resin include thermoplastic resins such as general-purpose plastics and engineering plastics exemplified below. Specific examples of general-purpose plastics include polyethylene, high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene (hereinafter sometimes referred to as “PS resin”), polyacetic acid. Examples thereof include vinyl, polytetrafluoroethylene, ABS resin (acrylonitrile-butadiene-styrene resin), AS resin (acrylonitrile-styrene resin), and acrylic resin. Specific examples of the engineering plastic include polyamide, nylon, polyacetal, polycarbonate, modified polyphenylene ether (hereinafter sometimes referred to as “modified PPE resin”), polybutylene terephthalate, polyethylene terephthalate, and cyclic polyolefin.

  Among open-cell foams using the foaming method and resin, for example, when used for vehicle interior materials, polyurethane foams, polystyrene (PS) foams from the viewpoint of versatility and moldability. Polypropylene foam, polyethylene foam and modified polyphenylene ether (PPE) foam are preferred. Furthermore, a modified polyphenylene ether (PPE) -based foam is more preferable from the viewpoints of recyclability, heat resistance, and rigidity.

  When an open-cell foamed sheet made of a modified polyphenylene ether (PPE) resin is used as the breathable sound absorbing layer in the present invention, the foamed cell membrane is partially or entirely open, and most of the cells are adjacent. As long as it communicates with the foamed cell, the surface layer portion may have a high-density layer, a so-called non-foamed layer or a partially closed cell layer. In addition, apart from being open-celled at the time of foam molding, as a post-processing, through-opening or non-through-hole forming may be performed to mechanically promote open-cell formation.

  In the present invention, the open cell ratio of the open cell foamed sheet made of the modified polyphenylene ether resin before the lamination and perforation of the non-breathable skin layer is 60% to 98% from the viewpoint of sound absorption. It is preferable that it is 70 to 85%. When the open cell ratio of the foamed sheet is less than 60%, the sound absorption effect may be reduced because incident sound waves cannot efficiently enter the open cell layer. Moreover, since the bending rigidity of a sheet | seat will fall extremely when a continuous cell rate exceeds 98%, even if the non-foamed layer which has bending rigidity is laminated | stacked, it may not satisfy the practical characteristics as an interior material.

  In the present invention, the “open cell ratio” means the ratio of the cells (closed cells) in which the foamed cells are completely isolated from the other foamed cells by the cell membrane and are independent (closed cell rate). The value was calculated as open cell ratio (%) = 100−closed cell ratio (%) after measurement according to ASTM D-2859 using a multi-pycnometer (manufactured by Beckman).

  Examples of the modified polyphenylene ether (PPE) resin include a mixture of a PPE resin and a PS resin, and a styrene / phenylene ether copolymer such as a graft copolymer of a styrene monomer to PPE.

  Specific examples of the PPE resin in the modified PPE resin include, for example, poly (2,6-dimethylphenylene-1,4-ether), poly (2-methyl-6-ethylphenylene-4-ether), poly (2,6-diethylphenylene-1,4-ether), poly (2,6-diethylphenylene-1,4-ether), poly (2-methyl-6-n-propylphenylene-1,4-ether) Poly (2-methyl-6-n-butylphenylene-1,4-ether), poly (2-methyl-6-chlorophenylene-1,4-ether), poly (2-methyl-6-bromophenylene- 1,4-ether), poly (2-ethyl-6-chlorophenylene-1,4-ether) and the like. These may be used alone or in combination of two or more. .

  Examples of PS resins that form mixed resins with PPE resins in modified PPE resins include styrene or derivatives thereof, such as α-methylstyrene, 2,4-dimethylstyrene, monochlorostyrene, dichlorostyrene, p-methyl. Examples thereof include resins mainly composed of styrene, ethyl styrene and the like. Therefore, the PS-based resin is not limited to a homopolymer composed of only styrene or a styrene derivative, but may be a copolymer made by copolymerizing with another monomer.

  On the other hand, specific examples of the styrene monomer that is polymerized, preferably graft-polymerized to the PPE resin, include, for example, styrene, α-methylstyrene, 2,4-dimethylstyrene, monochlorostyrene, dichlorostyrene, p-methyl. Examples include styrene and ethylstyrene. Among these, styrene is preferable in terms of versatility and cost. These may be used alone or in combination of two or more.

  Among the modified PPE resins, the cost is low, and by changing the mixing ratio, it is possible to easily obtain a resin having excellent quality such as heat resistance and rigidity, and having changed workability. It is preferably a mixed resin of a base resin and a PS base resin.

  The modified PPE resin in the present invention is preferably 25 to 70% by weight of PPE resin and 75 to 30% by weight of PS resin, 35 to 60% by weight of PPE resin and 65 to 40% by weight of PS resin. It is more preferable that If the PPE resin in the modified PPE resin is less than 25% by weight, the heat resistance tends to be inferior. If the PPE resin exceeds 70% by weight, the viscosity at the time of heat flow increases and foam molding becomes difficult. Tend to be.

  In addition, the resin constituting the open-cell foamed sheet of the present invention includes various additives such as a nucleating agent, an antioxidant, and a heat stabilizer as necessary, as long as the object of the present invention is not significantly impaired. An antistatic agent, a conductivity imparting agent, a weathering agent, an ultraviolet absorber, a flame retardant, an inorganic filler, and the like can be added.

  As described above, in order to efficiently obtain an extruded foam sheet layer using a modified PPE resin, a method of obtaining a foam sheet by extrusion foaming using a circular die is preferable from the viewpoint of workability.

  Extrusion foaming using a circular die is, for example, after mixing a base resin and another type of resin used as necessary, additives in a blender, and then supplying the extruder to the resin composition by melt-kneading, A foaming agent is injected under high temperature and high pressure, mixed, cooled to a suitable foaming temperature, and extruded and foamed from a circular die, which is a mold having an annular slit under atmospheric pressure, to obtain a cylindrical foam. A method of stretching and cooling with an annular cooling mandrel installed on the inner side of the cylindrical foam so as to cool from the inner surface side of the foam, and then cutting it and taking it up into a sheet shape. Examples of the extruder used for extrusion foaming include a one-stage type of one extruder and a two-stage type (tandem type) in which two extruders are connected in series. Among these, the two-stage system is particularly preferable for efficiently performing the plasticization of the resin, the mixing of the resin and the additive, and the cooling step of the resin, followed by the extrusion.

  Here, in the above extrusion process, in order to increase the open cell ratio of the open cell foamed sheet made of the modified polyphenylene ether resin, for example, (i) the temperature condition in the extruder and (ii) the amount of the foaming agent are adjusted. That's fine. More specifically, regarding (i), by setting the cooling temperature in the second-stage extruder to the high temperature side, an open cell layer can be provided as a whole in the thickness direction of the sheet. Regarding (ii), the foaming agent press-fitting amount may be set to about 1.2 to 2.0 times the amount used when producing a closed-cell foamed sheet with respect to 100 parts by weight of the base resin. However, if the foaming agent press-fitting amount is too large, plasticization proceeds and shear heat generation between the polymers is less likely to occur, so that the open cell ratio may decrease. These (i) to (ii) may be combined.

  As the hydrocarbon foaming agent used when obtaining an open-cell foamed sheet made of a modified polyphenylene ether resin, a volatile foaming agent is preferred, and specific examples include ethane, propane, butane, pentane and the like. It is done. Especially, the hydrocarbon type foaming agent whose Kauri butanol value (KB value) which shows the solubility of a foaming agent is 20-50 is preferable. In addition, it is also possible to use those having the above range by appropriately mixing two or more types having a KB value higher and lower than this range.

  In the present invention, among the specific examples of the foaming agent, butane has a moderate solubility of the foaming agent and a low dissipative property of the foaming agent. preferable. The butane may be isobutane, normal butane, or a mixture of isobutane and normal butane.

  In the present invention, the amount of injection of the hydrocarbon-based blowing agent during extrusion foaming is preferably 2.0 to 6.0 parts by weight, and 2.5 to 4.5 parts by weight with respect to 100 parts by weight of the constituent resin. More preferably. When the amount of the foaming agent injected is less than 2.0 parts by weight, good open cell foam cells or closed cell foam cells tend not to be obtained. When the amount exceeds 5.0 parts by weight, extrusion foaming becomes unstable. Or the surface roughness of the foam sheet tends to occur greatly.

  The thickness of the open-cell foamed sheet made of the modified polyphenylene ether resin is preferably 2.0 to 10 mm, and more preferably 3.5 to 6.0 mm. If the thickness of the foamed core layer is less than 2.0 mm, the function as an open cell layer tends to be hardly exhibited in the sound absorption performance. If it is greater than 10 mm, folding occurs or the volume increases. Productivity such as transportation tends to decrease.

Basis weight open cell foam sheet consisting of modified polyphenylene ether resin of the present invention is preferably ^{100~300g / m 2, 200~250g / m} 2 is more preferable. When the basis weight of the foamed core layer is smaller than 100 g / m ² , the rigidity tends to be insufficient, and when it exceeds 300 g / m ² , the lightness tends to decrease.

  The expansion ratio of the open-cell foamed sheet made of the modified polyphenylene ether resin in the present invention is preferably 5 to 25 times, and more preferably 15 to 20 times. When the foaming ratio of the foamed core layer is lower than 5 times, the flexibility is inferior and breakage due to bending or the like tends to occur. On the other hand, when the expansion ratio exceeds 25 times, the product tends to be large, and the productivity such as transportation tends to decrease.

  In the laminated base material in the present invention, by laminating the non-breathable skin layer on both sides of the open-cell extruded foam sheet, the structural rigidity required for use in vehicle interior materials and the like can be obtained. It is possible to prevent a person from breaking when carrying the material.

  Examples of the non-breathable skin layer laminated on both sides of the breathable sound absorbing layer in the present invention include a non-breathable film, a non-breathable sheet, and a closed cell foam sheet. These may be used alone. Two or more kinds may be laminated and used. In particular, from the viewpoint of rigidity, it is preferable to include a non-foamed material.

  Among these, it is preferable to use a thermoplastic resin film from the viewpoints of workability at the time of lamination, adhesiveness, light weight, and rigidity. The resin used for the thermoplastic resin film is preferably a modified PPE resin or a heat-resistant PS resin from the viewpoint of adhesiveness.

  In the present invention, when a film made of a modified PPE resin is used as a part of the non-breathable skin layer, the same one as described for the open-cell foamed sheet can be used. In addition to these, a rubber-based resin, specifically, a styrene-butadiene copolymer represented by high impact polystyrene (HIPS) may be mixed in order to improve impact resistance.

  In the present invention, when a heat resistant PS resin is used as part of the non-breathable skin layer, the heat resistant PS resin used is a copolymer of styrene or a derivative thereof and another monomer. can give. Examples of monomers having an effect of improving heat resistance and copolymerizable with styrene or derivatives thereof include unsaturated carboxylic acids such as maleic acid, fumaric acid, acrylic acid, methacrylic acid, and itaconic acid or derivatives thereof. And nitrile compounds such as acid anhydrides, acrylonitrile, methacrylonitrile, and derivatives thereof. These may be used alone or in combination of two or more.

  In addition, as the heat-resistant PS-based resin, when polymerizing styrene or a styrene derivative, synthetic rubber or rubber latex is added and polymerized, and maleic acid, fumaric acid, acrylic acid, methacrylic acid, itaconic acid, etc. It may be a copolymer with an unsaturated carboxylic acid or a derivative thereof and an acid anhydride thereof, a nitrile compound such as acrylonitrile or methacrylonitrile. Among these, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and acrylonitrile-butadiene-styrene copolymer are effective in improving heat resistance, versatility and cost. From the viewpoint of, it is preferable. The heat-resistant PS resin may be used alone or in combination of two or more.

  In the present invention, the heat-resistant PS resin may be blended with other thermoplastic resins. Examples of the thermoplastic resin to be blended include the modified PPE resin, PS resin, HIPS, polycarbonate, and polyester. And polyamides and copolymers thereof. Among these, modified PPE resin, PS resin, and HIPS are preferable from the viewpoints of versatility, uniform dispersion, and cost. A known HIPS can be used, and the content of the rubber component is usually 1 to 15% by weight.

  In the present invention, when a film is used as the air-impermeable skin layer, the resin composition of the film may be the same on both sides or different.

As described above, the non-breathable skin layer preferably includes a non-foamed layer. 50-300 micrometers is preferable and, as for the thickness of a non-foaming layer, 100-150 micrometers is more preferable. If the thickness of the non-foamed layer is smaller than 50 μm, the bending rigidity of the laminated foamed sheet is extremely lowered, and there is a tendency that it does not satisfy practical characteristics as an interior material. If the thickness is larger than 300 μm, the weight of the material increases, and handling properties are increased. Etc. tend to get worse.

Basis weight of the non-foamed layer in the present invention is preferably ^{50~300g / m 2, 90~150g / m} 2 is more preferable. When the basis weight of the non-foamed layer is lower than 50 g / m ² , the strength, rigidity, heat resistance and the like tend to decrease, and when higher than 300 g / m ² , the lightness tends to decrease.

  As a method of laminating the open-cell extruded foam sheet and the non-breathable skin layer in the present invention, the non-foamed layer is melted by using a hot roll, which is an example of a method of laminating via an adhesive or a thermal lamination method. A non-breathable skin layer melt-extruded from a T-die or the like, which is an example of a method in which a foamed sheet is pressure-bonded and laminated to the surface of the non-foamed layer or a binder lamination method (extrusion lamination method), is crimped to the extruded foam sheet The method of joining and laminating | stacking etc. are mentioned.

  Examples of the adhesive layer include thermoplastic adhesives such as vinyl acetate, cellulose, polyamide, and polyvinyl acetate; thermosetting adhesives such as urethane, melamine, phenol, epoxy, and acrylic. Rubber adhesives such as chloroprene rubber, nitrile rubber, and silicone rubber; natural product adhesives such as starch, protein, and natural rubber; polyolefin, modified polyolefin, ethylene-vinyl acetate copolymer resin, Hot melt adhesives such as polyamide, polyester, thermoplastic rubber, styrene-butadiene copolymer, styrene-isoprene copolymer; PS resin latex, styrene-butadiene (SB) resin latex, carboxy-modified SB Water-soluble emulsions such as resin latexes.

  The sound-absorbing substrate of the present invention, after laminating the non-breathable skin layer on the open-cell extruded foam sheet, by providing a hole reaching the inside of the open-cell extruded foam sheet from the surface of either non-breathable skin layer, Sound absorption is imparted. Here, in order to make the best use of the sound absorbing performance of the open cell foam sheet while maintaining the rigidity of the sound absorbing substrate, the thickness of the substrate is substantially reduced while having an appropriate opening. Preferably not.

  In the present invention, the method of providing the holes includes passing the sound-absorbing base material through a roll provided with a large number of needles, pressing a flat plate provided with a large number of needles against the sound-absorbing base material, contacting a thermal needle, The method of irradiating and opening is mentioned. Among these, from the viewpoint of workability and productivity, a sound-absorbing substrate is passed between rolls provided with a large number of needles (hereinafter sometimes referred to as “roll needles”), or flat plates provided with a large number of needles (hereinafter referred to as “roll needles”). A method in which a “flat needle” is sometimes pressed against a sound-absorbing substrate is preferable. More preferably, a roll needle is preferable because the surface pressure applied to the substrate during drilling is reduced and the effect of suppressing thickness reduction is high.

  In the present invention, using these methods, in order to perform a drilling process that has an appropriate opening but does not reduce the thickness, the opening diameter of the hole is in the range of 0.5 to 2.0 mm, and The opening pitch is preferably in the range of 6 to 20 mm. Furthermore, the opening pitch is more preferably in the range of 8 to 10 mm.

  When the opening pitch is less than 6 mm in the range of the opening diameter of 0.5 to 2.0 mm, the surface pressure applied to the base material at the time of drilling increases, and the thickness of the sound absorbing base material may be reduced. Therefore, there is a possibility that the sound absorption performance and rigidity are lowered. Moreover, when the opening pitch is larger than 20 mm, when the opening diameter is small, the sound entering the material is reduced, and the sound absorbing performance may be lowered.

  The opening diameter (equivalent circle diameter) in the present invention is preferably 0.5 to 2.0 mm, more preferably 1.0 to 1.5 mm, from the viewpoint of sound absorption and rigidity. When the opening diameter is larger than 2.0 mmφ, the rigidity may be lowered when the pitch is small. In addition, when the diameter of the opening is smaller than 0.5 mmφ, it is impossible to stably perform drilling, or when a needle is used, breakage tends to occur and productivity may be reduced.

  The shape of the needle is preferably a needle shape that can completely shear the substrate surface material at the time of opening so that the hole is not closed again even if the material is heat-treated. Specifically, a combination of a spindle shape and a cylindrical shape is preferable. More preferably, the length of the weight portion is shorter than the length of the needle entering the material.

  However, the perforation process in the present invention needs to be non-breathable as a whole interior material as a practical characteristic of the automobile interior material. This is because when the interior material has air permeability as a whole, the design surface may be contaminated in such a manner that dust or dust is filtered when the air flow in the vehicle passes through the interior material. In the present invention, it is necessary to perform drilling so as not to penetrate.

The opening diameter of the non-through hole in the present invention can be measured using, for example, the following method. (A) The base material in which the hole is formed is photographed at an appropriate magnification using, for example, an optical microscope or a normal camera.
(B) An OHP sheet is placed on the photographed image, and the portion corresponding to the hole is painted with black ink and copied (primary processing).
(C) The primary processing image is taken into an image processing apparatus (for example, PIAS-II, manufactured by Pierce Co., Ltd.), and whether or not the dark color portion and the light color portion are painted with black ink is identified.
(D) Using “FRACTAREA (area ratio)” in the image analysis calculation function, the area ratio (opening ratio) of the holes in the entire image is obtained by the following equation.
Opening ratio (%) = (area of dark color portion / area of entire image) × 100
(E) Count the number of through holes present in the photograph taken in the process of calculating the aperture ratio.
(B) The opening diameter of the equivalent circle diameter is calculated from the obtained opening ratio and the number of holes by the following formula.
Opening diameter = 2 × {area of entire image × (opening ratio (%) / 100) / (π × number of holes)} ^1/2

  The pitch of the non-through holes in the present invention is a value obtained by measuring the length of the side when the arrangement of the non-through holes is a lattice, and the distance from the nearest hole when the arrangement of the non-through holes is a staggered pattern.

  The sound-absorbing substrate in the present invention may be laminated with a skin material, if necessary, in the case where it is used in a site where design properties are required.

  As a material used for the skin material, any woven fabric, non-woven fabric, knitted fabric, felt, pad material, flexible foam, and a laminate of them may be used as long as they have a design property. Even things can be used.

Skin material, considering the quality and cost, preferably has a basis weight of 100 to 300 g / ^{m 2,} and more preferably has a basis weight of 120~200g / ^{m 2.} When the basis weight of the skin material is less than 100 g / m ^2, there is a tendency that a sufficient feel as an interior material cannot be obtained. On the other hand, if the basis weight of the skin material exceeds 300 g / m ² , the molding distortion of the skin material tends to affect thermal deformation.

  The sound-absorbing substrate in the present invention may be laminated and integrated with an anti-noise layer to prevent rubbing noise with the vehicle body or other vehicle interior materials, if necessary.

  As a material used for the noise prevention layer, a polyolefin resin film, a woven fabric or a non-woven fabric is preferably used, and a non-woven fabric is more preferably used.

  Examples of the polyolefin resin film include polyolefin resin films such as a polyethylene film and a polypropylene film, and the thickness of the film is preferably 10 to 100 μm, and more preferably 25 to 35 μm. In the case of undergoing a molding process in order to shape the sound-absorbing substrate according to the present invention into a vehicle interior material, the foamed laminated sheet is clamped to the center of a heating furnace provided with heaters on the top and bottom, and molded. There is a method of heating and softening so that the temperature is suitable for the surface (for example, the surface temperature of the foamed laminated sheet is 125 to 155 ° C.), followed by press cooling with a temperature-controlled mold and shaping.

  Specific examples of molding methods include plug molding, free drawing molding, plug and ridge molding, ridge molding, matched mold molding, straight molding, drape molding, reverse draw molding, air slip molding, plug assist. Examples of the method include molding and plug assist reverse draw molding.

  Next, although the foam sheet regarding this invention is demonstrated based on an Example and a comparative example, this invention is not limited only to this Example.

  Various physical property measuring methods and evaluation methods of the obtained sound-absorbing substrate are shown below.

(Thickness)
Using a scaled loupe (manufactured by PEAK, zoom scale loupe, magnification 15 times), the thickness at 20 arbitrary positions in the width direction was measured, and the average value of the measured values was calculated. The thickness between the holes was measured by measuring the portion between the holes.

(Handling rigidity)
Three specimens each having a MD (length) direction of 150 mm × TD (width) direction of 50 mm and a MD direction of 50 mm × TD direction of 150 mm were sampled from the substrates obtained in the examples and comparative examples, and then 23 ° C. and Normal state adjustment was performed by leaving it in an atmosphere of 50% RH for 24 hours.
Using the obtained test piece, set it on a three-point bending test jig (distance between fulcrums of 100 mm, wedge R3.2 mm) so that the indoor side becomes the upper surface, and load the center part at a speed of 50 mm / min. In addition, the bending elastic gradient was measured according to JIS K7203.
Practical characteristics were taken into account from the measured bending elastic gradient, and judgment was made using the following criteria.
○: Bending elastic gradient 55 N / 50 mm / cm or more.
X: Bending elastic gradient is less than 55 N / 50 mm / cm.

(Sound absorption)
[Maximum sound absorption rate]
About the sound-absorbing base material obtained by the Example and the comparative example, according to ASTM-E-1050, the normal incidence sound absorption coefficient was measured by 1/3 octave band, and the maximum value (alpha) of the sound absorption coefficient was calculated | required.
[Decrease in sound absorption performance during drilling]
Further, the sound absorbing performance lost in the drilling process was determined as follows.
1) A base material (blank base material) before punching was collected.
2) Openings having the same opening diameter and pitch as those of the sound-absorbing substrate were formed one by one so as not to reduce the thickness of the blank substrate, thereby obtaining a perforated blank substrate.
3) With respect to the obtained perforated blank base material, the normal incident sound absorption coefficient was measured with a 1/3 octave band according to ASTM-E-1050, and the maximum value of the sound absorption coefficient was α ₀ .
4) 1- (α / α ₀ ) was regarded as the sound absorbing performance lost. ○: α was 0.5 or more, and 1- (α / α ₀ ) was less than 0.2.
X: α is less than 0.5, or 1- (α / α ₀ ) is 0.2 or more.

(Fabric sheet weight)
In the foamed sheet before forming the holes, after cutting out 5 test pieces each having a size of 430 mm in the MD direction and 430 mm in the TD direction and measuring their weights, the average value was calculated and converted to 1 m ² to obtain the entire sheet. The basis weight.

(Foaming ratio of foam sheet)
The density df of the foamed sheet before forming the holes was measured according to JIS K7222, and the density df of the base resin was separately measured according to JIS K7112, and calculated by the formula: foaming ratio = dp / df.

Example 1
[Preparation of breathable sound absorbing layer]
As the base resin of the extruded foam sheet, a modified PPE resin (manufactured by GE Plastics, NORYL EFN-4230: PPE / PS ratio (weight ratio) so that the PPE resin component is 40% by weight and the PS resin component is 60% by weight. ) = 70/30) A modified PPE resin obtained by mixing 57.1 parts by weight and 42.9 parts by weight of PS resin (PS Japan Co., Ltd., G8102: PS component = 100) was used.
100 parts by weight of the modified PPE resin, 0.34 parts by weight of talc (manufactured by Hayashi Kasei Co., Ltd., Talcan Powder PK), 0.08 parts by weight of magnesium stearate (manufactured by Sakai Chemical Industry Co., Ltd., SM-1000) And 0.05 parts by weight of polybutene (manufactured by Nisseki Polybutene, LV-50) were mixed with stirring using a ribbon blender. The obtained blend is supplied to a tandem extruder in which a 115 mmφ extruder (first stage extruder) and a 152 mmφ extruder (second stage extruder) are connected in series so that the resin temperature becomes about 280 ° C. In addition, after being melt-kneaded in the first-stage extruder, a hydrocarbon-based blowing agent (iso-butane / n-butane = 85/15 wt%) as a blowing agent is added to 4.100 parts by weight of the modified PPE resin. 1 part by weight of the mixture was press-fitted and mixed. Thereafter, the cylinder temperature of the second stage extruder was cooled to 200 ° C., and then extruded from a circular die at 190 kg / hour under atmospheric pressure. The resulting cylindrical foam is made into a sheet by cutting it with a cutter while taking it at 10 m / min while molding it using a mandrel (external diameter is 445 mm, temperature controlled to 40 ° C. with circulating water), A length of 120 m was wound using a winding core material having a diameter of 260 mm so as to form a cylindrical roll having a diameter of 800 mm. Then, this winding core material was extracted and the roll-shaped material of the foam sheet (A-1) of the said form was obtained.
The obtained foamed sheet (A-1) had an expansion ratio of 19 times, an open cell ratio of 85%, a basis weight of 270 g / m ² , a sheet width of 1400 mm, and a sheet thickness of 5.3 mm.

[Lamination of non-breathable skin layer]
In order to laminate a non-foamed layer on one side of the extruded foam sheet (A-1), it was modified so that the PPE resin component was 10.0% by weight, the PS resin component was 79.3% by weight, and the rubber component was 10.7% by weight. 14.3 parts of PPE resin (manufactured by GE Plastics, NORYL EFN-4230) and 85.7 parts of HIPS (manufactured by PS Japan, H8117: PS / rubber ratio (weight ratio) = 87.5 / 12.5) , Supplied to an extruder, extruded into a film using a T-die, and from the opposite side of the foamed sheet (A-1), a water needle punch having a basis weight of 25 g / m ² as a nonwoven fabric for preventing abnormal noise By supplying a nonwoven fabric (manufactured by Yuho Co., Ltd., Ceres S8020) and thermocompression bonding the three layers, an outdoor non-breathable skin layer and a noise-preventing layer having a basis weight of 120 g / m ² (thickness 0.12 mm) Multiply Layered.
Next, 21.4 parts of modified PPE resin (on the surface opposite to the laminated surface) so that the PPE resin component is 15.0% by weight, the PS resin component is 84.4% by weight, and the rubber component is 0.6% by weight ( Nippon GE Plastics, NORYL EFN 4230), PS resin 73.6 parts (PS Japan, polystyrene H8102) and HIPS 5.0 parts (PS Japan, H8117) are fed to the extruder and T-die It was extruded into a film, and an indoor non-breathable skin layer having a basis weight of 120 g / m ² (thickness 0.12 mm) was laminated to obtain a base material (B-1) having a thickness of 4.8 mm.
[Drilling]
A flat plate needle having needles with a diameter of 1.5 mmφ arranged at an 8 mm pitch is pressed with a press pressure of 30 kN / m ² from the indoor skin layer surface of the obtained base material (B-1) to a depth of 4.6 mm. Thus, a non-through hole was provided to obtain a sound-absorbing substrate (C-1).
Handling rigidity evaluation and sound absorption evaluation were performed on the obtained sound-absorbing substrate (C-1). The results are shown in Table 1.

(Example 2)
[Drilling]
A sound-absorbing substrate (C-2) was obtained in the same manner as in Example 1 except that the needle diameter and pitch of the flat needle were changed to 1.6 mmφ and 10 mm pitch.
Handling rigidity evaluation and sound absorption evaluation were performed on the obtained sound-absorbing substrate (C-2). The results are shown in Table 1.

(Example 3)
[Drilling]
A sound-absorbing substrate (C-3) was obtained in the same manner as in Example 2 except that the pressing pressure was 70 kN / m ² .
Handling rigidity evaluation and sound-absorbing property evaluation were performed with respect to the obtained sound-absorbing base material (C-3).
The results are shown in Table 1.

Example 4
[Drilling]
A non-through hole was formed by allowing the base material (B-1) to pass between a roll having a roll needle in which needles having a diameter of 1.4 mmφ were arranged at a pitch of 7.5 mm and a rubber roll. At that time, the roll having the roll needle is set on the surface side of the indoor skin layer of the base material (B-1), the clearance is adjusted to a depth of 4.6 mm, and pressed under a pressing condition of a linear pressure of 6 kg / cm. Thus, a non-through hole was provided to obtain a sound absorbing base material (C-4).
Handling rigidity evaluation and sound absorption evaluation were performed on the obtained sound-absorbing substrate (C-4).
The results are shown in Table 1.

(Example 5)
[Drilling]
A sound-absorbing substrate (C-5) was obtained in the same manner as in Example 4 except that the needle diameter and pitch of the roll needle were changed to 1.4 mmφ and 8.9 mm pitch.
Handling rigidity evaluation and sound-absorbing property evaluation were performed with respect to the obtained sound-absorbing base material (C-5).
The results are shown in Table 1.

(Example 6)
[Drilling]
A sound-absorbing substrate (C-6) was obtained in the same manner as in Example 4 except that the needle diameter and pitch of the roll needle were changed to 1.4 mmφ and 10.8 mm pitch.
Handling rigidity evaluation and sound absorption evaluation were performed on the obtained sound-absorbing substrate (C-6).
The results are shown in Table 1.

(Example 7)
[Drilling]
A sound-absorbing substrate (C-7) was obtained in the same manner as in Example 6 except that the press pressure (linear pressure) was 10 kg / cm.
Handling rigidity evaluation and sound-absorbing property evaluation were performed with respect to the obtained sound-absorbing base material (C-7). The results are shown in Table 1.

(Comparative Example 1)
[Drilling]
A sound-absorbing substrate (C-8) was obtained in the same manner as in Example 1 except that the needle diameter and pitch of the flat needle were changed to 1.4 mmφ and 4.4 mm pitch.
Handling rigidity evaluation and sound-absorbing property evaluation were performed with respect to the obtained sound-absorbing base material (C-8). The results are shown in Table 1.

(Comparative Example 2)
A sound-absorbing substrate (C-9) was obtained in the same manner as in Example 4 except that the needle diameter and pitch of the roll needle were changed to 1.4 mmφ and 4.1 mm pitch.
Handling rigidity evaluation and sound absorption evaluation were performed on the obtained sound-absorbing substrate (C-9). The results are shown in Table 1.
(Comparative Example 3)
A sound-absorbing substrate (C-10) was obtained in the same manner as in Example 1 except that the needle diameter and pitch of the flat needle were changed to 1.5 mmφ and 30 mm pitch.
Handling rigidity evaluation and sound-absorbing property evaluation were performed with respect to the obtained sound-absorbing base material (C-10). The results are shown in Table 1.

Claims (4)

  A sound-absorbing base material comprising a non-breathable skin layer laminated on both sides of a breathable sound-absorbing layer, and having a non-through hole that reaches the breathable sound-absorbing layer from the surface of one of the non-breathable skin layers, A sound-absorbing base material, wherein the through-holes have an opening diameter of 0.5 to 2.5 mm and a pitch of 6 to 20 mm.   The sound-absorbing base material according to claim 1, wherein the air-permeable sound-absorbing layer comprises an open-cell foamed sheet.   The sound-absorbing base material according to claim 1 or 2, wherein the breathable sound-absorbing layer comprises an open-cell foamed sheet made of a modified polyphenylene ether resin.   A method for producing a sound-absorbing base material comprising a non-breathable skin layer laminated on both sides of a breathable sound-absorbing layer, and a non-penetrating hole is provided from the surface of one of the non-breathable skin layers. After laminating a non-breathable skin layer on the layer, a needle having a pitch of 6 to 20 mm is pressed against a roll disposed on the peripheral surface to provide a non-through hole. A method for producing a sound-absorbing substrate.