JP6920717B2 - Manufacturing method of sound absorbing material, sound absorbing molded product, sound absorbing molded product - Google Patents

Description

The present invention relates to a method for manufacturing a sound absorbing material, a sound absorbing molded product, a sound absorbing molded product, etc. used for, for example, a fender liner, an engine undercover, a body undercover, a transmission cover, etc. in a vehicle such as an automobile.

Conventionally, vehicles such as automobiles have fender liners and engine underscores in order to prevent noise such as collision noise of pebbles and road noise during driving and to protect the body from collision (chipping) of pebbles and the like. A sound absorbing molded product such as a cover is attached.
In the sound-absorbing molded product, a porous material such as glass wool, rock wool, felt, etc. is used as a layer on the body side of the vehicle to impart sound absorption, rigidity, strength, etc., and a non-woven fabric skin material is used on the road surface side. As the layer, a sound-absorbing material of a multilayer composite having sound absorbing properties, design properties, etc. is used (see, for example, Patent Document 1). Further, for the purpose of improving water resistance and chipping resistance, a sound absorbing material of a multilayer complex in which a film, a resin sheet or the like is interposed between layers in addition to a porous material or a non-woven fabric is provided (). For example, see Patent Documents 2 and 3).
The sound-absorbing material is formed into a predetermined shape by heat press molding using a mold to obtain the sound-absorbing molded product (see, for example, Patent Documents 4 and 5). An adhesive that can be softened and melted by heat during heat press molding is mainly used for adhering the skin material to the base material (see, for example, Patent Documents 6 and 7).
However, most of the adhesives that can be softened and melted by heat during heat press molding are made of thermoplastic resin and are easily softened and melted in a high temperature environment. Therefore, the adhesive is used for adhering the skin material. The sound-absorbing material used has difficulty in heat resistance and adhesive strength in a high-temperature environment in order to be used as a fender liner or an engine undercover around a high-temperature engine. Examples of the adhesive having excellent heat resistance and adhesive strength in a high temperature environment include an adhesive made of phenol resin (see, for example, Patent Document 8). The phenol resin adhesive cures in a short time in an environment of a mold temperature of 180 ° C. to 220 ° C. and a molding time of 30 seconds to 2 minutes during heat press molding (see, for example, Patent Document 9), and is heat resistant. In addition to its properties, it is also excellent in water resistance, and has good adhesiveness and workability. Therefore, it is suitable as an adhesive used for the above-mentioned sound-absorbing materials and sound-absorbing molded products.

Japanese Unexamined Patent Publication No. 2005-35411 JP-A-2009-298340 Japanese Unexamined Patent Publication No. 2015-205688 Japanese Unexamined Patent Publication No. 2012-214003 Japanese Unexamined Patent Publication No. 2013-86599 Japanese Unexamined Patent Publication No. 9-12028 Japanese Unexamined Patent Publication No. 2012-245925 JP-A-2010-090490 Japanese Unexamined Patent Publication No. 2006-305479

However, since the adhesive made of phenol resin has high fluidity and good flow, it easily penetrates into the skin material. Then, the adhesive that has soaked into the skin material exudes to the surface of the skin material during heat press molding of the sound absorbing material, and adheres the skin material to the mold surface of the mold. Therefore, there are problems that the surface of the skin material is roughened and the appearance is deteriorated, and the releasability of the sound absorbing molded product is deteriorated. In particular, when a film, a resin sheet, or the like is interposed between the base material and the skin material, the adhesive is prevented from being transferred to the base material by the film, the resin sheet, or the like. Most of the material soaks into the skin material and oozes out to the surface of the skin material in a large amount during heat press molding. Therefore, the skin material is firmly adhered to and fixed to the mold surface of the mold, and the releasability is extremely high. Deteriorate. In order to suppress the adhesion and adhesion of the skin material to the mold by the adhesive, it is necessary to set the mold temperature to a low temperature of 130 ° C to 160 ° C and prolong the curing time of the adhesive. However, there arises a problem that the work efficiency becomes extremely poor.
The present invention has focused on such problems existing in the prior art. An object of the present invention is to provide a sound absorbing material, a sound absorbing molded product, and a method for producing a sound absorbing molded product, which can suppress deterioration of mold releasability without deteriorating sound absorbing performance and working efficiency. be.

As a means for solving the above-mentioned conventional problems, the sound absorbing material according to claim 1 is made of a base material made of a porous material impregnated with a thermosetting resin and an adhesive powder on one surface of the base material side. It has a non-woven fabric skin material provided with an adhesive surface, and the non-woven fabric in the non-woven fabric contains 80% by mass or more of polyester fibers and has a mass of 20 to 150 g / m ^{2 per unit area.} The gist is that there is.
The invention according to claim 2 is the invention of the sound absorbing material according to claim 1, wherein the adhesive powder is a novolak type phenol resin using hexamine as a curing agent, and is a JIS K6910 phenol resin test method. 5.11.1 Flow The gist is that the flow specified in Method A is 10 to 30 mm / 125 ° C.
The gist of the invention according to claim 3 is that in the invention of the sound absorbing material according to claim 1 or 2, the amount of the adhesive powder applied to the non-woven fabric is 5 to 20 g / m ^2. do.
The invention according to claim 4 is the invention of the sound absorbing material according to any one of claims 1 to 3, wherein the thermosetting resin is a resole-type phenolic resin in the base material. The gist is that the porous material is glass wool, and a film material made of a synthetic resin is laminated on one surface of the base material on the skin material side.
The gist of the invention of the sound-absorbing molded product according to claim 5 is that the sound-absorbing material according to any one of claims 1 to 4 is formed in a predetermined shape.
The invention of the method for producing a sound-absorbing molded product according to claim 6 is obtained by forming the sound-absorbing material according to any one of claims 1 to 4 into a predetermined shape by heat press molding. Is the gist.

[Action]
The sound-absorbing material of the present invention has a base material made of a porous material and a skin material made of a non-woven fabric. The base material is made of a porous material to impart sound absorbing property and rigidity to the sound absorbing material, and the skin material is made of a non-woven fabric to give the sound absorbing material sound absorbing property and design. Giving sex.
The base material is impregnated with a thermosetting resin. The thermosetting resin is cured by heating when the sound absorbing material is formed into a predetermined shape, so that the migration from the base material to the skin material is suppressed, and in addition, the thermosetting resin is made of a porous material. Since suitable strength, shapeability, etc. are imparted to the base material, deterioration of releasability can be suppressed without lowering work efficiency.
An adhesive surface made of an adhesive powder is provided on one surface of the skin material on the base material side. When the sound-absorbing material is molded into a predetermined shape, the adhesive surface is cured after the adhesive powder is melted or softened, thereby suitably joining the skin material and the base material.
The non-woven fabric used for the skin material contains 80% by mass or more of polyester fibers, and by imparting suitable shapeability to the skin material, a decrease in work efficiency is suppressed. In addition, the non-woven fabric has a mass of 20 to 150 g / m ² per unit area from the viewpoint of suppressing deterioration of mold releasability while maintaining desired sound absorption performance. When the mass per unit area of the non-woven fabric ^{is less than 20 g / m 2} , the adhesive powder in a melted or softened state easily moves from the adhesive surface to the surface of the non-woven fabric, resulting in poor releasability. .. If the mass per unit area of the non-woven fabric ^{exceeds 150 g / m 2} , the air permeability of the non-woven fabric deteriorates, so that the desired sound absorption performance cannot be obtained (claim 1).

Further, when the adhesive powder is a novolak type phenol resin using hexamine as a curing agent, it is suitably melted or softened by heating when the sound absorbing material is formed into a predetermined shape, and the heat resistance after curing is improved. Since it is high, it is possible to improve the adhesive strength and heat resistance. Further, as the adhesive powder, a novolak type phenol-based resin having a flow specified in the 5.11.1 flow A method of the JIS K6910 phenol resin test method at 10 to 30 mm / 125 ° C. is used. The migration from the adhesive surface to the surface of the non-woven fabric can be suppressed, and the releasability of the sound absorbing material can be made suitable (claim 2).
Further, by setting the coating amount of the adhesive powder to the non-woven fabric to 5 to 20 g / m ² , the design property of the sound absorbing material is made suitable for the adhesive strength of the skin material to the base material. And releasability can be made suitable. If the coating amount is ^{less than 5 g / m 2} , the desired adhesive strength cannot be obtained. When the coating amount ^{exceeds 20 g / m 2} , the melted or softened adhesive powder easily moves from the adhesive surface to the surface of the non-woven fabric, resulting in poor design and releasability (claim 3).
Further, when the thermosetting resin is a resole-type phenol-based resin and the porous material is glass wool, the base material is easy to handle and has good work efficiency. In addition, by laminating a film material made of a synthetic resin on one surface of the base material on the skin material side, the film material prevents the transfer of the thermosetting resin from the base material to the skin material. Therefore, it is possible to improve the design and releasability of the sound absorbing material (claim 4).

The sound-absorbing molded product of the present invention is formed by forming the sound-absorbing material into a predetermined shape, and by using the sound-absorbing material, the sound-absorbing performance and work efficiency are lowered as described above. Deterioration of releasability can be suppressed without this (claim 5).
In the method for producing a sound-absorbing molded product of the present invention, the sound-absorbing material is formed into a predetermined shape by heat press molding, and deterioration of mold releasability can be suppressed without deteriorating sound absorbing performance and work efficiency. By using the sound-absorbing material that can be produced, the work efficiency can be made suitable (claim 6).

〔effect〕
According to the sound-absorbing skin material and the sound-absorbing molded product of the present invention, deterioration of mold releasability can be suppressed without deteriorating sound absorbing performance and working efficiency. Further, according to the method for producing a sound absorbing molded product of the present invention, the work efficiency can be made suitable.

FIG. 5 is a cross-sectional view showing a sound absorbing material of the embodiment. FIG. 5 is a cross-sectional view showing another form of sound absorbing material.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.
As shown in FIG. 1, the sound absorbing material 10 of the present embodiment is composed of a base material 11 and a skin material 12 laminated on one surface (upper surface in FIG. 1) of the base material 11. An adhesive surface 12A is provided on one surface (lower surface in FIG. 1) of the skin material 12 on the base material 11 side, and the base material 11 and the skin material 12 are joined by the adhesive surface 12A. ing.
Further, as shown in FIG. 2, the sound absorbing material 10 is formed by laminating a film material 13 on one surface (upper surface in FIG. 2) of the base material 11 on the skin material 12 side. The film material 13 can also be interposed between the skin material 12 and the skin material 12.
The sound-absorbing molded product such as the fender liner, the engine undercover, the body undercover, and the transmission cover is formed by forming the sound-absorbing material 10 into a desired predetermined shape. In the production of the sound absorbing molded product, heat press molding at a temperature of 180 ° C. or higher is adopted for forming the sound absorbing material 10 into a predetermined shape.
The sound absorbing material 10 is configured by laminating the skin material 12 on both surfaces (upper surface and lower surface in FIG. 1) of the base material 11 so that the adhesive surface 12A faces the base material 11 side. You may. Further, in the sound absorbing material 10, when the skin material 12 is laminated on both sides of the base material 11, the film material 13 is laminated on both sides of the base material 11 (upper surface and lower surface in FIG. 2). The film material 13 may be interposed between the base material 11 and the skin material 12, respectively.

The base material 11 imparts sound absorbing property, rigidity, and shape retention when made into a sound absorbing molded product to the sound absorbing material 10, and is made of a porous material.
Examples of the porous material include an inorganic porous material using glass wool, rock wool, asbestos fiber, carbon fiber, ceramic fiber, metal fiber, whiskers, etc., or a breathable polyurethane foam, a breathable polyethylene foam, or a breathable material. Breathable plastic foams such as breathable polypropylene foams, breathable polystyrene foams, breathable phenolic resin foams, and breathable melamine resin foams are exemplified. Among those exemplified, glass wool is desirable as a porous material used for the base material 11 from the viewpoints of high heat resistance, easy availability, and easy handling.

By impregnating the porous material with a thermosetting resin, it is possible to impart heat resistance, improve rigidity, and improve moldability and shape retention while making sound absorption suitable.
Examples of the thermosetting resin include resole-type phenol-based resin, urethane-based resin, melamine-based resin, thermosetting-type acrylic resin (particularly those that form an ester bond by heating and are cured), urea-based resin, and epoxy-based resin. , Thermosetting polyester resin and the like are exemplified. In addition, urethane-based resin prepolymer, urea-based resin prepolymer (initial condensate), phenol-based resin prepolymer (initial condensate), diallyl phthalate prepolymer, acrylic oligomer, polyvalent isocyanate, methacrylic ester monomer, diallyl phthalate monomer. Examples of synthetic resin precursors such as prepolymers, oligomers, and monomers. As the thermosetting resins exemplified above, it is preferable to use an aqueous solution, an aqueous emulsion, or an aqueous dispersion from the viewpoint of easy handling, but those in the form of an organic solvent solution may also be used. Further, two or more kinds of the thermosetting resin or the synthetic resin precursor may be mixed and used.
Among the illustrated thermosetting resins, the resole-type phenol-based resin is desirable as the one to be impregnated with the porous material of the base material 11 from the viewpoints of being easily available, easy to handle, and having high heat resistance. The resol-type phenol-based resin is obtained by reacting a phenol-based compound with an excess of formaldehyde and using an alkali catalyst, and is composed of a mixture of various phenolic alcohols to which phenol and formaldehyde are added, and is usually provided as an aqueous solution. Will be done.

As the resorcinol-type phenolic resin, a phenol-alkylresorcin cocondensate is more desirable, and in particular, a polyhydric phenol mixture obtained by carbonization of an Estonian oil shale has a long pot life, is inexpensive, and is 5-methylresorcin. In addition, it is useful because it contains a large amount of various highly reactive alkylresorcins.
A catalyst or a pH adjuster may be mixed with the resole-type phenol-based resin, if necessary, and a curing agent such as formaldehyde or an alkylolated triazine derivative may be added and mixed. In addition, the water-soluble resol-type phenol-based resin may be sulfomethylated and / or sulfimylated for the purpose of improving stability. Details regarding the sulfomethylated and / or sulfimethylated resin are described in, for example, Japanese Patent No. 3393927 and Japanese Patent No. 3339959.

In the base 11, the mass per unit area of the porous material, sound absorption, rigidity, from the viewpoint of the shape retention and the like to obtain ^favorable be 100g / ^{m 2} ~2000g / m 2 ^preferably, it is more desirable to ^{150g / m 2 ~1500g / m 2} , it is further desirable to ^{200g / m 2 ~1000g / m 2} . If the mass per unit area is excessively small, the desired performance in terms of sound absorption, rigidity, etc. cannot be exhibited. If the mass per unit area is excessively large, the weight increases and the desired sound absorption cannot be exhibited.
In the base material 11, the amount of the thermosetting resin impregnated into the porous material suppresses the transfer of the thermosetting resin to the skin material 12 while improving the rigidity, shape retention, and the like. From this point of view, it is desirable to set the ratio to 5% by mass to 30% by mass of the mass per unit area.
In addition to impregnating the heat-curable resin, the porous material is optionally a higher fatty acid such as stearic acid or palmitic acid, a higher alcohol such as palmityl alcohol or stearyl alcohol; butyryl stearate, glycerin mono. Esters of fatty acids such as stearate; fatty acid amides; carnauba wax; paraffins; paraffin oil; natural waxes and synthetic waxes such as Oils, pigments, dyes, antioxidants, antistatic agents, crystallization accelerators, phosphorus compounds, nitrogen compounds, sulfur compounds, boron compounds, bromine compounds, guanidine compounds, phosphate compounds, storic acid Flame retardants such as ester compounds and amino resins, expanded graphite, flame repellents, insect repellents, preservatives, surfactants, lubricants, antiaging agents, ultraviolet absorbers and the like may be added.

The film material 13 is made of a synthetic resin, and is used for the purpose of improving the water resistance and chipping resistance of the sound absorbing material 10. Further, since the film material 13 prevents the thermosetting resin impregnated in the porous material of the base material 11 from migrating to the skin material 12, the thermosetting resin oozes on the surface of the skin material 12. It is possible to prevent deterioration of releasability and deterioration of design due to the appearance. Further, as the film material 13, a perforated film having a large number of holes formed can be used from the viewpoint of improving sound absorption.
Examples of the synthetic resin include thermoplastic resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyamide resin, polyester resin, and acrylonitrile-butadiene copolymer. Is exemplified. The film material 13 made of a thermoplastic resin is melted and softened by heating when the sound absorbing material 10 is formed into a predetermined shape, and is solidified after molding to be adhered to the base material 11.
The thickness of the film material 13 is preferably 0.01 to 0.5 mm, more preferably 0.05 to 0.4 mm, and even more preferably 0.05 to 0.3 mm. If the film material 13 is excessively thin, durability such as chipping resistance cannot be sufficiently obtained. If the film material 13 is excessively thick, problems such as an increase in weight, obstruction of ventilation of the base material 11, and deterioration of sound absorption performance occur.

The skin material 12 imparts sound absorption, design, and strength to the sound absorbing material 10, and is made of a non-woven fabric made of fibers.
The non-woven fabric contains 80% by mass or more of polyester fibers from the viewpoints of improving heat resistance, imparting water absorption suppressing performance, imparting suitable shaping property, and the like. If the content of the polyester fiber is less than 80% by mass, the desired performance such as heat resistance and shapeability cannot be obtained, and particularly sufficient water absorption suppressing performance cannot be exhibited.
Examples of fibers that can be used in addition to the polyester fibers include polyethylene fibers, polypropylene fibers, polyamide fibers, acrylic fibers, urethane fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, acetate fibers, polymetaphenylene isophthalamide fibers and poly-p. -Aramid fiber such as phenylene terephthalamide fiber, polyarylate fiber, polyether ether ketone fiber, synthetic fiber such as polyphenylene sulfide fiber, biodegradable fiber (polylactic acid fiber) composed of starch extracted from plants such as corn and sugar cane, Natural fibers such as cellulose fibers, pulps, cotton, palm fibers, hemp fibers, bamboo fibers and Kenaf fibers, inorganic fibers such as glass fibers, carbon fibers, ceramic fibers and asbestos fibers, or scraps of textile products using these fibers. An example is a regenerated fiber obtained by defibrating. In the non-woven fabric, only the polyester fiber or one or more of the polyester fiber and the exemplified fiber is used.
The fibers used in the non-woven fabric have a softening point of 220 ° C. or higher from the viewpoint of suppressing deterioration of mold releasability by being fused to the mold by heating when the sound absorbing material 10 is formed into a predetermined shape. Is preferable. In particular, polyester fibers having a softening point of 220 ° C. or higher are relatively inexpensive, easily available, and are useful in that they have flame retardancy.
For the non-woven fabric, a spunbond method in which a thermoplastic resin which is a material of the fiber is discharged into a long fiber shape and formed into a sheet shape, a method in which a web sheet or mat of the fiber is entangled by needle punching, and the like. The thermal bond method in which the web sheet or mat of the fiber is heated to soften and bind the low melting point thermoplastic fiber, or the web sheet or mat of the fiber is impregnated or mixed with a synthetic resin binder and bound. The chemical bond method, or the stitch bond method, in which the web sheet or mat of the fiber is entangled by needle punching and then the low melting point thermoplastic fiber is heated and softened to be bound, or the fiber is sewn with a thread, or the fiber. Those manufactured by the span race method or the like in which the fibers are entwined with a high-pressure water stream are used.
Similar to the porous material, the non-woven fabric is impregnated with a thermosetting resin, natural waxes, synthetic waxes, water repellents and oil repellents, pigments, dyes, antioxidants, antistatic agents, etc. Crystallization accelerators, flame retardants, flame retardants, insect repellents, preservatives, surfactants, lubricants, antistatic agents, UV absorbers and the like may be added.

The adhesive surface 12A is provided on one surface of the skin material 12 in order to bond the skin material 12 to the base material 11. When the adhesive surface 12A is provided, solid adhesive powder is sprinkled on one surface of the skin material 12 in order to prevent the adhesive from penetrating into the non-woven fabric of the skin material 12 during the production of the sound absorbing material 10. Will be done. Examples of the adhesive powder include powders of low melting point thermoplastic resins having a melting point of 60 ° C. to 180 ° C., such as novolak type phenolic resin, polyethylene resin, polyester resin, polyamide resin, and ethylene-vinyl acetate copolymer. One or more of these are used.
In the sound absorbing material 10, the adhesive powder softened and melted by heating when formed into a predetermined shape may permeate into the non-woven fabric and exude to the surface thereof, thereby deteriorating the releasability. In particular, the sound-absorbing material 10 in which the film material 13 is interposed significantly exudes to the surface of the non-woven fabric because the softened / melted adhesive powder is prevented from being transferred into the base material 11. Therefore, it is desirable to use an adhesive powder that does not easily penetrate into the non-woven fabric in a softened / melted state.
Of the above-exemplified ones, it is desirable to use a novolak type phenolic resin as the adhesive powder. The novolak-type phenol-based resin is obtained by reacting formaldehyde with an excess of phenol with an acid catalyst, and is composed of various dihydroxydiphenylmethane-based derivatives in which phenol is further condensed with phenol alcohol. Then, the novolak-type phenol-based resin is added to hexamine as a curing agent and kneaded with a hot roll at 80 ° C. to 120 ° C. to adjust the curing reaction so that the non-woven fabric is softened and melted. It is possible to adjust the permeability, in other words the degree of flow at a given temperature.
Specifically, the degree of flow at the predetermined temperature can be specified by the 5.11.1 flow A method of the JIS K6910 phenol resin test method. It is desirable to adjust the flow of the novolak type phenolic resin according to the above specifications to 10 to 30 mm / 125 ° C. If the flow is less than 10 mm / 125 ° C., the softened / melted adhesive powder becomes difficult to spread, and sufficient adhesive strength cannot be obtained. When the flow exceeds 30 mm / 125 ° C., the adhesive powder in a softened / melted state easily permeates into the non-woven fabric.

^{In the skin material 12, the non-woven fabric has a mass of 20 g / m 2} per unit area from the viewpoint of suppressing the penetration of the adhesive powder in a softened / melted state while maintaining suitable sound absorption. It is said to be ~ 150 g / m ^2. Mass per the unit area is preferably ^{30g / m 2 ~120g / m 2} , more desirably ^{30g / m 2 ~110g / m 2} . If the mass per unit area ^{is less than 20 g / m 2} , the permeation of the adhesive powder in the softened / melted state cannot be suppressed.
In the skin material 12, the coating amount for the nonwoven fabric of the adhesive powder is desirably 5 to 20 g / ^{m 2,} more desirably 5 to 15 g / ^{m 2,} in 8~13g / ^{m 2} It is even more desirable to have. If the coating amount is excessively small, sufficient adhesive strength cannot be obtained. If the amount of coating is excessively large, the adhesive powder in a softened / melted state seeps out to the surface of the non-woven fabric, and the releasability deteriorates.
In the skin material 12, the average particle size of the adhesive powder by the sieving method is preferably in the range of 10 to 100 μm, more preferably in the range of 20 to 100 μm, and even more preferably in the range of 50 to 100 μm. When the average particle size is excessively small, when the adhesive powder is sprayed, the powder is scattered and it becomes difficult to spread the adhesive powder uniformly, and the fine powder is tightly packed to form the adhesive on the adhesive surface 12A. The density of the powder becomes high, the adhesive surface 12A becomes a film without holes, and the sound absorbing performance of the skin material 12 tends to deteriorate. If the average particle size is excessively large, the state of spraying the adhesive powder on the adhesive surface 12A may become rough, and the molten adhesives may not be bonded to each other and the adhesive strength may decrease, and the skin material 12 The melt of the adhesive powder exudes to the surface of the adhesive powder, which deteriorates the releasability and the appearance quality. Further, the adhesive powder having large particles melts and spreads widely to form a film-like film without holes, which hinders air permeability and deteriorates sound absorption performance.
From the viewpoint of improving the sound absorption performance of the skin material 12, the ventilation resistance is preferably set to 0.2 to 5.0 kPa · s / m. The ventilation resistance is more preferably 0.25 to 4.5 kPa · s / m, still more preferably 0.3 to 4.0 kPa · s / m. If the ventilation resistance of the skin material 12 is excessively low, it becomes difficult for the sound absorbing material 10 to exhibit sound absorbing performance because it becomes difficult to buffer the sound waves. If the ventilation resistance of the non-woven fabric is excessively high, it becomes difficult to impart the desired sound absorbing property to the sound absorbing material 10.
The ventilation resistance (Pa · s / m) refers to a value measured by a breathability tester (product name: KES-F8-AP1, manufactured by Kato Tech Co., Ltd., steady flow differential pressure measurement method). do.

Hereinafter, examples in which the present invention is further embodied will be described, but the present invention is not limited to these examples.

(A) Non-woven fabric: A spunbonded non-woven fabric made of polyester fiber (softening point: 238 ° C.), and four types having the following mass per unit area (A-1) to (A-4) were used.
(A-1) Mass per unit area: 50 g / m ² .
(A-2) Mass per unit area: 20 g / m ² .
(A-3) Mass per unit area: 15 g / m ² .
(A-4) Mass per unit area: 155 g / m ² .

(B) Adhesive powder: Hexamine was added in an amount of 15% by mass as a curing agent to a novolak-type phenol-based resin having a molar ratio of phenol / formaldehyde = 1.0 / 0.9, and 90 ° C. to 90 ° C. using a heating roll. Four types were used, which were kneaded at 110 ° C., the average particle size was 80 to 100 μm, and the flow according to the above regulation was adjusted to the following (B-1) to (B-4).
(B-1) Flow: 15 mm / 125 ° C.
(B-2) Flow: 30 mm / 125 ° C.
(B-3) Flow: 40 mm / 125 ° C.
(B-4) Flow: 60 mm / 125 ° C.

^{(C) Porous base material: Uncured glass wool having a mass of 800 g / m 2} and a thickness of 50 mm, to which a resole-type phenol-based resin was added as a binder, was used.

(D) Film material: A polypropylene film having a thickness of 0.1 mm was used.

(E) Skin material: The adhesive powder of (B) is applied to one side of the non-woven fabric of (A) by sinter processing ^{so as to have a coating amount of 10 g / m 2} , and then heated at 90 ° C to 100 ° C. (B) The adhesive powder was temporarily adhered to one side of the (A) non-woven fabric to obtain a skin material.
(F) Sound-absorbing molded product: After laminating the (D) film material on one side of the (C) porous base material and further laminating the (E) skin material on the surface of the (D) film material. Molding was performed with a heat press molding machine at 210 ° C. for 60 seconds to obtain a sound absorbing material. The sound absorbing material has a shape having an uneven portion having a thickness of 3 mm at the peripheral portion having a square frame shape in a plan view and a thickness of 5 to 10 mm at the central portion inside the peripheral portion.

[Evaluation of sound absorption performance]
The ventilation resistance of the above (E) skin material was measured and evaluated in the following two stages. The results are shown in Table 1.
◯: The ventilation resistance is in the range of 0.2 to 5.0 kPa · s / m.
X: The ventilation resistance is outside the range of 0.2 to 5.0 kPa · s / m.

[Evaluation of releasability]
The mold releasability when molding the above-mentioned (F) sound-absorbing molded product was evaluated in the following three stages. The results are shown in Table 1.
⊚: No adhesive adheres to the press mold, and the molded product can be released from the press mold without resistance.
Δ: Adhesive adheres to the press mold at places where crimping becomes large depending on the molding shape, and there are places where the mold release from the press mold is partially poor.
X: Adhesive adheres significantly to the press mold, and it is impossible to release the molded product from the press mold without damaging the molded product.

[Appearance evaluation]
The appearance of the above-mentioned (F) sound-absorbing molded product was visually evaluated and evaluated in the following three stages. The results are shown in Table 1.
⊚: The molding shape is good, the appearance is beautiful, and the design is good.
Δ: The molded shape is good, but the surface of the skin material is fluffed and the design is impaired.
X: The molded shape is broken, the skin material is peeled off or broken, and the design is poor.

[Discussion]
From the results in Table 1, the sound-absorbing molded products of Examples 1 to 8 had a ventilation resistance of the skin material in the range of 0.2 to 5.0 kPa · s / m, and there was no problem in releasability and appearance. rice field.
^{In Comparative Examples 1 and 2 in which} the mass of the non-woven fabric in the skin material per unit area was 15 g / m 2, the ventilation resistance of the skin material was in the range of 0.2 to 5.0 kPa · s / m, but the sound absorption property. The evaluation was x for the releasability and appearance of the molded product.
In Comparative Examples 3 and 4 in which the mass of the non-woven fabric in the skin material per unit area was 155 g / m ² , the ventilation resistance of the skin material was outside the range of 0.2 to 5.0 kPa · s / m.
Further, in the sound-absorbing molded products of Examples 1 to 4 in which the flow of the adhesive powder is within the range of 10 to 30 mm / 125 ° C., the mold releasability and the appearance are all evaluated as ⊚. The sound-absorbing molded products of Examples 5 to 8 having a flow of 40 mm / 125 ° C. or 60 mm / 125 ° C. were all evaluated for mold releasability and appearance as Δ.
From the above, it is shown that the mass per unit area of the non-woven fabric in the skin material needs to be within the range of ^{20 to 150 g / m 2 in order to make the sound absorption property, the mold releasability, and the appearance suitable.} Was done.
Further, it was shown that it is possible to improve the releasability and the appearance by setting the flow of the adhesive powder within the range of 10 to 30 mm / 125 ° C.

The method for producing a sound-absorbing material, a sound-absorbing molded product, and a sound-absorbing molded product of the present invention can be used industrially because it can suppress deterioration of mold releasability without deteriorating sound absorbing performance and work efficiency. be.

10 Sound absorbing material 11 Base material 12 Skin material 12A Adhesive surface 13 Film material

Claims (4)

It has a base material made of a porous material impregnated with a thermosetting resin, and a non-woven fabric skin material having an adhesive surface made of an adhesive powder on one surface on the base material side.
The non-woven fabric in the skin material contains 80% by mass or more of polyester fibers and has a mass of 20 to 150 g / m ² per unit area.
The adhesive powder is a novolak-type phenol-based resin using hexamine as a curing agent, and the flow specified in the 5.11.1 flow A method of the JIS K6910 phenol resin test method is 10 to 30 mm / 125 ° C. der is,
The adhesive powder has an average particle size of 10 to 100 μm by a sieving method.
The amount of the adhesive powder applied to the non-woven fabric is 5 to 20 g / m ² .
Sound absorbing material made of a synthetic resin film material is characterized that you have been interposed between the skin material and the base material. In the substrate, the thermosetting resin is a resol-type phenolic resin, the sound absorbing material according to claim 1, wherein the film material is laminated on one surface serving as the skin material side of the substrate. A sound-absorbing molded product according to claim 1 or 2 , wherein the sound-absorbing material is formed in a predetermined shape. A method for producing a sound-absorbing molded product, which is obtained by forming the sound-absorbing material according to claim 1 or 2 into a predetermined shape by heat press molding.

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