JPH11152456A - Production of heat-adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-adhesive sheet useful for automotive interiors and the like and improving the coating yield of adhesive powder without staining the periphery of a substrate with the adhesive powder by spraying the surface of the substrate with a specific dispersion of the adhesive powder and sucking from the rear side. SOLUTION: By spraying a dispersion 8 of hot melt adhesive powder on the surface of an air-permeable substrate sheet 1, simultaneously sucking the dispersion from the back side to coat the substrate sheet 1 with the adhesive powder, and subsequently drying the sprayed coating. It is preferable that the substrate sheet is impregnated with a synthetic resin such as polyethylene and that a threading thickener such as sodium polyacrylate is dissolved in the dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sheet having thermal adhesiveness.

[0002]

BACKGROUND OF THE INVENTION For example, automotive interior materials are manufactured by thermally bonding a skin material lined with a hot melt adhesive sheet to a substrate. The skin material is, for example, a fiber knitted fabric, a nonwoven fabric, or the like. However, if the skin material is lined with a hot-melt adhesive sheet, the adhesive pressure is exerted on the surface during the thermal bonding with the base material, so that it does not work effectively and uniformly, so that a large adhesive force is required, and uneven bonding is required. May occur. Further, there is a problem that the air permeability of the skin material is impaired by the hot melt adhesive sheet and the soundproofing property is reduced, and air is trapped between the skin material and the base material during bonding.

[0003]

2. Description of the Related Art As a means for solving the above-mentioned problems of using a hot-melt adhesive sheet, recently, a hot-melt adhesive powder dispersion has been spray-coated on the back surface of a skin material to form a thermal adhesive layer. Provided (Japanese Unexamined Patent Publication No.
No. 291275). According to the thermal adhesive layer, the adhesive pressure is applied pointwise, so that it works effectively and uniformly, and the permeability of the skin material is not hindered.

[0004]

However, in the above prior art, when a hot melt adhesive powder dispersion is sprayed on a surface to be coated such as a back surface of a skin material, the hot melt adhesive powder is sprayed on the surface to be coated. However, there is a problem that the powder is rebounded by the impact at the time of spraying and scatters around the surface to be coated, thereby contaminating the periphery, and the yield of the hot melt adhesive powder is deteriorated.

[0005]

According to the present invention, as a means for solving the above-mentioned conventional problems, a dispersion in which a hot-melt adhesive powder (8A) is dispersed on the surface of a gas-permeable base sheet (1) is provided.
It is intended to provide a method for producing a thermoadhesive sheet (1A) which is applied by spraying (8) and suctioning from the back side, and then dried. The hot melt adhesive powder dispersion
It is preferable that (8) dissolves a spinnable thickener as a dispersion stabilizer, and the breathable base sheet (1) may be impregnated with a synthetic resin.

[0006] The breathable base sheet (1) used in the present invention is, for example, polyester fiber, polyethylene fiber, polypropylene fiber, polyamide fiber, acrylic fiber, urethane fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, acetate fiber. Synthetic fiber such as pulp, cotton, wool, coconut fiber, hemp fiber, bamboo fiber, etc., inorganic fiber such as glass fiber, carbon fiber, ceramic fiber, asbestos, and scrap of fiber products using these fibers Knitted or non-woven fabric consisting of one or more fibers such as regenerated fibers obtained by defibrating, or polyurethane, polyethylene, polypropylene, polyamide,
Open-cell sheets and porous sheets of plastics such as polyester and polyvinyl chloride; and the breathable base sheet (1) includes, for example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer. Coalescing, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, fluororesin, thermoplastic acrylic resin, thermoplastic polyester, thermoplastic polyamide,
One or more thermoplastic synthetic resins such as thermoplastic urethane resin, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer and / or urethane resin, melamine resin, thermosetting Acrylic resin, urea resin,
One or more thermosetting synthetic resins such as a phenol resin, a resorcin resin, an alkyl resorcin resin, an epoxy resin, and a thermosetting polyester may be impregnated. When impregnating the synthetic resin, the impregnation amount is usually 2 to 5
00 g / m ² . In order to impregnate the synthetic resin into the air-permeable base sheet (1), the synthetic resin is immersed in a solution or emulsion of the synthetic resin or the solution or emulsion is sprayed with a spray gun, a roll coater, a knife coater or the like. Apply to one or both sides of sheet (1) and dry. When impregnated with a thermosetting synthetic resin, the thermosetting synthetic resin may be cured by heating at the time of the drying. A foaming agent may be added to the synthetic resin solution or emulsion impregnated in the air-permeable base sheet.

The hot-melt adhesive powder dispersion (8) is sprayed on the surface of the breathable substrate sheet (1) by a spray gun. The hot melt adhesive used in the hot melt adhesive powder dispersion (8) is, for example, polyethylene,
Polyolefin resin such as polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, or a modified product of the polyolefin resin, polyvinyl chloride, polyurethane, polyester, polyester copolymer, polyamide, polyamide copolymer The hot-melt adhesive is usually a powder having a size of about 20 to 400 mesh.

[0008] The hot melt adhesive powder is usually 5
~ 60% by weight. The water contains one or more thickeners such as methylcellulose, methoxycellulose, ethylcellulose, ethoxycellulose and carboxymethylcellulose, for example, higher alcohol sulfate (Na salt or amine salt), alkyl allyl sulfonate ( Na salt or amine salt), alkyl naphthalene sulfonate (Na salt or amine salt), alkyl naphthalene sulfonate condensate, alkyl phosphate, dialkyl sulfosuccinate, rosin soap, fatty acid salt (Na salt or amine salt) Isoanionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylol alcohol Emissions, polyoxyethylene alkyl amide, sorbitan alkyl esters, nonionic surfactants such as polyoxyethylene sorbitan alkyl esters, octadecylamine acetate, imidazoline derivative acetate, polyalkylene polyamine derivative or salt thereof,
One or two or more surfactants such as cationic surfactants such as octadecyltrimethylammonium chloride, trimethylaminoethylalkylamide halogenide, alkylpyridinium sulfate and alkyltrimethylammonium halide may be added as a dispersant. . It is particularly desirable to use a spinnable thickener as the dispersant. Examples of the spinnable thickener include, for example, polyacrylic acid, polymethacrylic acid, sodium metal such as alginic acid, potassium, alkali metal salts such as lithium, water-soluble synthetic polymers such as polyethylene oxide, trolley mallow, gluten, below oil, There is a water-soluble natural polymer composed of a vegetable mucilage such as Norrythus japonica, and a particularly desirable spinning thickener is sodium polyacrylate. The amount of the spinnable thickener to be added depends on its molecular weight, and is usually added so that the viscosity of the hot melt adhesive powder dispersion during spraying is 50 to 10,000 cps / 25 ° C. For example, the addition amount in the case of sodium polyacrylate having a viscosity average degree of polymerization of about 38,000 is 0.01 to
It is about 1.0% by weight.

Further, the above-mentioned hot melt adhesive powder dispersion
(8) For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinylidene chloride resin, styrene resin, vinyl acetate resin, fluorine resin, thermoplastic Acrylic resin, thermoplastic polyester, thermoplastic polyamide, thermoplastic urethane resin, epoxy resin, melamine resin, urea resin, phenol resin, resorcin resin,
Thermosetting resins such as alkyl resorcinol resins, synthetic resin emulsions such as acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, silicon rubber, urethane rubber, fluorine rubber Compound rubber, polysulfide rubber, graft rubber, butadiene rubber, isoprene rubber, chloroprene rubber, polyisobutylene rubber,
Polybutene rubber, isobutene-isoprene rubber, acrylate-butadiene rubber, styrene-butadiene rubber,
Acrylonitrile-butadiene rubber, pyridine-butadiene rubber, styrene-isoprene rubber, acrylonitrile-chloroprene rubber, styrene-chloroprene rubber,
Styrene-butadiene-styrene copolymer, styrene-
Synthetic rubber and elastomer powders such as isoprene-styrene copolymer, styrene-hydrogenated polyolefin-styrene copolymer, butadiene-styrene block copolymer, styrene-rubber intermediate block-styrene copolymer and other block copolymers Or an emulsion may be added.
If necessary, fillers such as calcium carbonate, talc, gypsum, carbon black, wood flour, walnut flour, coconut husk,
Pigments, dyes, flame retardants, flame retardants, insect repellents, preservatives, antioxidants, ultraviolet absorbers, fluorescent dyes, surfactants, foaming agents,
Paraffin, wax, silicone and other softeners and water repellents,
Alternatively, a release agent or a plasticizer may be added.

When the hot melt adhesive powder dispersion (8) is spray-coated on the surface of the air-permeable base sheet (1), the hot melt adhesive powder is sucked from the back side of the base sheet (1). The hot-melt adhesive powder is prevented from splashing due to the impact during spraying, and the hot-melt adhesive powder is applied to the base sheet.
(1) Adsorb to the surface. The hot melt adhesive powder dispersion
The spray application amount of (8) is usually 5 to 40 g / solid
m ² . When the above spinning thickener is used, the hot melt adhesive powder dispersion liquid (8) has a spinel-like structural viscosity, so that when sprayed, it is not dispersed in a mist form, but becomes a nodular droplet. Attaches to the surface to be coated. Such nodular droplets do not enter between the fuzz even if they are fuzzy on the surface to be coated, and adhere to the surface. Therefore, after drying, a state in which the hot melt adhesive powder efficiently adheres to the surface to be coated is obtained.

After spraying the hot melt adhesive powder dispersion on the surface of the air permeable base sheet (1) as described above, the base sheet (1) is dried by heating. The conditions for the heating and drying are 100 to 200 ° C. for about 1 to 5 minutes at a temperature equal to or higher than the melting point of the hot melt adhesive generally used.
When the thermosetting synthetic resin is impregnated in the base sheet (1), the thermosetting synthetic resin may be cured at the time of the heating and drying.

The heat-adhesive sheet composed of the base sheet coated with the hot-melt adhesive powder is adhered to an interior base material, for example, as a skin material of an automobile interior material. As the interior base material, for example, resin board (felt in which fibers are bound using a synthetic resin as a binder), cardboard, polystyrene foam, synthetic resin-impregnated polyurethane foam, hard polyurethane foam, plywood, hard board, particle board, fiber reinforcement Polyester resin (FRP) board, fiber or glass fiber similar to the fiber used for skin material,
Inorganic fibers such as ceramic fibers, metal fibers, rock wool, etc. are made of polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, fluororesin, heat Thermoplastic synthetic resins such as thermoplastic acrylic resin, thermoplastic polyester, thermoplastic polyamide, thermoplastic urethane resin, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, urethane resin, and melamine A fiber board bonded with a thermosetting synthetic resin such as a resin, a thermosetting acrylic resin, a urea resin, a phenol resin, a resorcin resin, an alkyl resorcin resin, an epoxy resin, and a thermosetting polyester is used. The heat-adhesive sheet of the present invention is used not only as a skin material of an automobile interior material but also as a backing material of a base material of an automobile interior material, a core material of clothes and the like.

Example 1 A hot melt adhesive powder dispersion was prepared according to the following formulation. Ethylene-vinyl acetate copolymer (EVA) powder ^{* 1} 35% by weight water 65〃 ^{* 1} : Melting point 90 ° C., 200 mesh pass As the breathable base sheet, a needle-punched nonwoven fabric made of polyester fiber was used. As shown in FIG. 1, the base sheet (1) is withdrawn from a roll (2) and introduced on a permeable belt conveyor (3) made of a net or felt.
Vacuum suction is performed from the back side by a suction box (4) in contact with the back surface of the belt conveyor (3). A vacuum path (5) with a valve (6) is connected to the suction box (4). In this state, the hot melt adhesive powder dispersion (8) was sprayed from above onto the surface of the base sheet (1) by a spray device (7). The dispersion (8) is stirred by a stirrer (10) in a stirrer (9) and fed into the spray device (7) by a pump (11).

The hot melt adhesive powder dispersion (8) is applied to the surface of the base sheet by the above spray at a solid content of 15 g / m ² , and the hot melt adhesive powder dispersion (8) is applied as described above. During the spraying, since the base sheet (1) is sucked from the back side by the suction box (4), the hot melt adhesive powder is applied to the base sheet.
(1) Adsorbed without splashing and splashing on the surface due to spray impact. After spraying the dispersion in this manner, the base sheet (1) is introduced into a drying chamber (12), and
It was dried by heating and drying at 50 ° C. for 2 minutes. In this way, a heat-adhesive sheet (1A) in which EVA powder (8A) is fixed on a base sheet (1), which is a polyester fiber needle-punched non-woven fabric as shown in FIG. Cut to dimensions. The base sheet to which the adhesive was not applied was superimposed on the adhesive-applied surface of the heat-adhesive sheet, and pressed with an iron having a hanging surface of 140 ° C. to thermally bond the two. The bonded sample was tested for 18
As a result of the 0 ° peeling test, the adhesive strength was 1.2 kg.
/ Cm.

As shown in FIG. 3, for example, a fiber sheet obtained by mixing hemp fiber and polypropylene fiber at a 1: 1 weight ratio and binding by needle punch is used as an interior base material (14). Is softened by heating at 250 ° C. for 30 seconds, and the heat-adhesive sheet (1A) is superimposed thereon as a skin material, and a cold press apparatus comprising a lower mold (15A) and an upper mold (15B)
(15), cold-pressed to form the interior base material (14) into an automobile ceiling shape and at the same time the heat-adhesive sheet (1A)
Is adhered to the interior substrate (14) by residual heat when the interior substrate (14) is softened by heating. In this manner, a ceiling material (16) for an automobile as shown in FIG. 4 is manufactured.

Comparative Example A thermoadhesive sheet was produced in the same manner as in Example 1 without performing suction using a suction box. In the case of the heat-adhesive sheet, the suction by the suction box was not performed during the spray application, so that the EVA powder rebounded and scattered on the surface of the base sheet, so that the application amount was reduced to 12 g / m ² as a solid content. The heat-adhesive sheet was heat-bonded to a substrate sheet to which no adhesive was applied in the same manner as in Example 1. The bonded sample was subjected to 180
° Peeling test showed that the adhesive strength was 0.9 kg /
cm.

Example 2 A hot melt adhesive powder dispersion was prepared according to the following formulation. Polyamide (PA) powder ^{* 1} 30% by weight Polybutyl acrylate emulsion ^{* 2} 10 {Sodium polyacrylate ^{* 3} 0.3 ^} Residual water ^{* 1} : Melting point 130 ° C., 200 mesh pass ^{* 2} : Solid content 50% by weight ^{* 3} : Viscosity average degree of polymerization of 38000 As a breathable substrate sheet, a 50% by weight aqueous solution of an alkylresorcinol resin was spray-coated on the surface of a nonwoven polypropylene fiber, and then heated and dried at 100 ° C. for 5 minutes to simultaneously cure the alkylresorcinol resin. Was used.
The resin impregnation rate of the base fabric was 15 g / m ² as a solid content.

The hot melt adhesive powder dispersion is spray-coated on the surface of the base sheet. In the case of this embodiment, at the time of spray coating, as shown in FIG.
A suction hopper (17) is arranged on the back side of (1) to perform suction. The suction hopper (17) includes a hopper (18) and the hopper
(18) Consists of a gas-permeable ceramic layer (19) stretched over the upper surface and a vacuum path (20) with a valve (21) communicating with the hopper (18). The coating amount of the hot melt adhesive powder dispersion (22) was 10 g / m ² as a solid content. 160 after application
C. for 1 minute. The thus-prepared heat-adhesive sheet and the base sheet to which no adhesive was applied were overlapped, pressed with an iron having a hanging surface of 150 ° C., and both were heat-bonded. The bonded sample was subjected to the same 180 ° peeling test as in Example 1, and as a result, the adhesive strength was 1.4 kg / cm.

[0019]

According to the present invention, when the hot melt adhesive powder dispersion is spray-coated on the air permeable base sheet, the hot melt adhesive powder is sucked from the back side of the base sheet. Therefore, the yield of the hot melt adhesive powder is improved without the surrounding being contaminated by the hot melt adhesive powder.

[Brief description of the drawings]

 1 to 4 relate to an embodiment.

FIG. 1 is a manufacturing process diagram of a heat-adhesive sheet.

FIG. 2 is a side sectional view of a heat-adhesive sheet.

FIG. 3 is an explanatory view at the time of press-fitting molding.

FIG. 4 is a perspective view of a ceiling material.

FIG. 5 is an explanatory view of a spraying process in Example 2.

[Explanation of symbols]

 1 Air-permeable base sheet 1A Thermal adhesive sheet 3 Belt conveyor 4 Suction box 5 Vacuum path 7 Spray device 8,22 Hot melt adhesive powder dispersion 8A EVA powder (hot melt adhesive powder) 12 Drying room

Claims (3)

[Claims] 1. A method for producing a heat-adhesive sheet, which comprises spraying a dispersion of a hot-melt adhesive powder on the surface of a gas-permeable base sheet, applying the dispersion by suction from the back side, and then drying. Method 2. The method according to claim 1, wherein a spinnable thickener is dissolved in the hot melt adhesive powder dispersion. 3. The method according to claim 1, wherein said base fabric is impregnated with a synthetic resin.