JP3135366B2 - Interior material molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneously bonding and molding a core material and a skin material formed of a mat mainly composed of inorganic fibers, and more particularly, to a method of interposing a cushion layer between them. The present invention relates to a molding method of an interior material suitable for use in a vehicle field, particularly a ceiling material or the like, which is subjected to press molding.

[0002]

2. Description of the Related Art Conventionally, the following method has been used to bond a core material made of a thermoplastic resin and a skin material.

(1) First, a thermoplastic resin sheet is formed into a required shape, trimming is performed to cut off the periphery of the molded product, an adhesive is applied to the surface of the obtained core material, and a woven fabric or polychlorinated resin is applied. A skin material consisting of vinyl / urethane foam or polyethylene foam / primer is adhered to the core material.

(2) A core material made of a thermoplastic resin and a skin material made of a woven fabric or a polyvinyl chloride / urethane foam / hot melt adhesive are simultaneously bonded.

[0005]

However, the former method has disadvantages that the lead time is long, the cost is high, and the number of steps is large.

In the latter method, wrinkles occur when the skin material is placed on the core material due to insufficient rigidity of the skin material, and the defect rate is high. In addition, the cost increases because of the provision of the hot melt layer. Further, an open-cell flexible polyurethane layer having a small thickness that does not adversely affect the adhesive strength may be interposed between the core material and the skin material. This urethane layer has excellent moldability and is commonly used. However, in the simultaneous molding / adhesion method of the skin material and the core material, unevenness of the core material easily appears on the surface of the skin material, and a high quality molded product is obtained. I can't.

In view of the above, an object of the present invention is to provide a method of bonding and molding a core material and a skin material, which can be carried out in a cost-effective manner with a small number of steps and is free from wrinkles or irregularities. In.

[0008]

The method for bonding a core material and a skin material according to the present invention has been devised to achieve the above-mentioned object. This is a method that can be implemented in a cost-effective manner by reducing the number and does not cause wrinkles or irregularities.

That is, according to the molding method of the present invention, between a core material and a skin material formed of a mat containing inorganic fibers as a main component, 30 to 70% by weight of a polypropylene resin is used.
And 70 to 30% by weight of polyethylene resin,
First, a foaming ratio of 20 times or more and a thickness of 3 mm or less are interposed with a cushion layer of a foam , and press-molding is performed by a molding die.

In a preferred embodiment of the present invention,
The core material has a polyolefin-based resin layer outside a mat mainly composed of inorganic fibers .

The polypropylene-based resin is not particularly limited as long as it is based on polypropylene, and includes a propylene homopolymer, a block copolymer or a blend thereof, propylene and another olefin,
It may be a copolymer of vinyl acetate, acrylic acid, acrylic acid ester, or the like, or a block copolymer, a random block, or a random copolymer of a polypropylene resin and another olefin resin.

[0012] The polypropylene resin may have a density of 0.1.
Those having 900 to 1.20 and a melt index of 0.8 to 60 are preferred.

The polyethylene resin is not particularly limited as long as it is based on polyethylene.
Homopolymers of ethylene, ethylene and other olefins,
It may be a copolymer with vinyl acetate, acrylic acid, acrylate, or the like, or a block, random block, or random copolymer of a polyethylene resin with another olefin resin. As the polyethylene resin, a density of 0.910 to 0.970 and a melt index of 0.9
To 7 are preferred.

In a mixture of a polypropylene resin and a polyethylene resin for forming a foam, the ratio of the polypropylene resin to the polyethylene resin is 30.
%: 70% to 70%: 30%. If this ratio deviates from the above range, it is not possible to obtain a molded product having excellent moldability and adhesiveness and having no wrinkles and irregularities.

As the foam of the polyolefin resin mixture, those obtained by various methods as described below can be applied.

A) A foaming agent is mixed into a mixture of a polypropylene resin and a polyethylene resin, and the resin mixture is extruded into a sheet by an extruder to produce a non-crosslinked polyolefin foam sheet, or The resin mixture is extruded into a sheet while a foaming agent is injected thereinto to produce a non-crosslinked polyolefin foam sheet.

B) A foaming agent and a crosslinking aid are mixed into a mixture of a polypropylene resin and a polyethylene resin, and the resin mixture is formed into a sheet by an extruder or a calender roll to produce a foamable sheet. The sheet is heated to simultaneously perform crosslinking and foaming to produce a crosslinked polyolefin foam sheet, or a foaming agent or a crosslinking aid is mixed into a mixture of a polypropylene resin and a polyethylene resin, and the extruder or calender is used. After forming into a sheet with a roll or the like, the sheet is irradiated with radiation such as an electron beam, crosslinked, and then heated and foamed to produce a crosslinked polyolefin-based foamed sheet (so-called pre-crosslinking).

The method of crosslinking a resin molded product includes electron beam, α
There are a method using ionizing radiation such as X-rays, β-rays, γ-rays, X-rays and ultraviolet rays, and a method of heating a resin composition to which an organic peroxide is added. In the former case, the irradiation dose is usually 1 to
20 Mrad.

As the crosslinking aid, a bifunctional monomer such as divinylbenzene, divinylnaphthalene, 1,9-nonanediol dimethacrylate, diallyl phthalate, or a trifunctional monomer such as trimethylolpropane trimethacrylate or triallyl trimellitate is used. Can be 1.0: 1.0 to bifunctional monomer and trifunctional monomer
A mixture of 2.0, preferably 1.0: about 1.5 is used. The preferable addition amount of the crosslinking aid is as follows.
It is 1.0 to 4.0 parts by weight with respect to 0 parts by weight.

As the blowing agent, azodicarbonamide,
An organic decomposition type foaming agent such as dinitrosopentamethylenetetramine, allophanoic acid amide, p, p'-oxybisbenzenesulfonyl hydrazide, and an inorganic decomposition type foaming agent such as sodium bicarbonate can be appropriately used. Of these, azodicarbonamide or those based thereon are preferred. In order to accelerate the decomposition of the foaming agent, a known decomposition aid such as zinc oxide or zinc stearate may be appropriately added. The preferred amount of the foaming agent is 5 to 20 parts by weight based on 100 parts by weight of the resin.

The mixture of the polypropylene resin and the polyethylene resin contains an antioxidant, a heat stabilizer, a metal harm inhibitor,
Inorganic fillers, ultraviolet absorbers, pigments, petroleum resins and the like can be added as needed.

The expansion ratio of the polyolefin resin foam is
20 times or more. When the expansion ratio is less than 20 times, the cost increases.

[0023] In addition, the thickness of the cushion layer is formed when the cushioning property is insufficient thin, so delicate molding of the thickened when the surface is poor, shall be the 3.0mm or less.

The flexural rigidity of the cushion layer made of a polyolefin resin foam has an expansion ratio of 20 times or more and a thickness of 3.
0 mm or less, preferably 1.0 g · cm / mm
² or more. The melting point of the cushion layer is 170 ° C. or less. Regarding the heat resistance of the cushion layer, the dimensional change after heating at 120 ° C. for 2 hours is 3.0% or less.

As the skin material, a woven fabric, a nonwoven fabric, a polyvinyl chloride sheet and a thermoplastic polyolefin sheet are preferably used.

On the other hand, as the core material as the adherend, a mixture or bonded product of inorganic fibers and a thermoplastic resin is preferably used. As the inorganic fibers, glass wool, rock wool, ceramic fibers, carbon fibers, and the like are used, and the length is preferably 5 to 200 mm. Further, the thickness is preferably 2 to 30 μm. Further, as the thermoplastic resin, those having a melting point of 70 to 270 ° C. are preferable,
For example, polyolefins such as polyethylene and polypropylene, saturated polyesters, polyamides, polystyrenes and the like are used alone or in combination of two or more.

The core material may have a polyolefin resin layer on the outside of a mat mainly composed of inorganic fibers. As the polyolefin resin, the above-mentioned polypropylene resin, polyethylene resin and the like are used. The outer polyolefin-based resin layer is preferably formed integrally with the thermoplastic resin fiber of the inner mat by welding.

In molding, first, the core material is heated. The heating of the core material is performed by, for example, hot air, a heater or a combination thereof, and the surface temperature of the core material is usually 17 ° C.
Made around 0 ° C.

Separately, a composite of the cushion layer and the cosmetic skin material is formed.

Next, a cushion layer of the above composite is arranged on one side of the heated core material, and then the three-layer laminate is molded and integrated with a press mold. The press molding temperature is preferably 100 ° C. or lower, and is appropriately set according to the relationship between the temperature at which the core material is plasticized by heating and the temperature close to the melting point (170 ° C. or lower) of the cushion layer. The pressing pressure is preferably 0.1 to 5 kg / cm ² , and the pressing time is preferably 10 to 30 seconds.

The laminate is shaped into a desired shape such as a ceiling material for an automobile by molding with the press mold.

The cushion layer may contain the same material or a material similar to the material contained in the core material.

[0033]

Next, an embodiment of the present invention will be described.

Example 1 a) Preparation of Cushion Layer Polypropylene (Density = 1.1, Melt Index =
1.0) A resin blend of 30 parts by weight and 70 parts by weight of a linear low-density polyethylene (density = 0.920, melt index = 4), 7 parts by weight of azodicarbonamide as a foaming agent, and a crosslinking aid , 1.0 part by weight of trimethylolpropane trimethacrylate and 1.5 parts by weight of 1,9-nonanediol dimethacrylate were added, respectively.
The obtained compound was melt-kneaded with a twin-screw extruder (120φ), and the kneaded material was extruded at a temperature equal to or lower than the decomposition temperature of azodicarbonamide to form a sheet having a thickness of 1.5 mm.

Then, the sheet was irradiated with an electron beam of 6.0 Mrad to crosslink the sheet, and then heated in a hot air foaming furnace.
It foamed by heating at 0 ° C.

Thus, the expansion ratio is 25 times and the thickness is 2.0 m.
Thus, a cushion layer made of a foamed sheet having a thickness of m was obtained.

B) Preparation of core material Glass fiber (thickness 10 μm, length 50-100 mm) and high-density polyethylene fiber (thickness 30 μm, length 51 m)
m, melting point 135 ° C.) in a weight ratio of 3: 1 to a card machine, and mixed to form a mat. This was subjected to 20 needle punches per 1 cm ² to obtain a mat-like material.

A high-density polyethylene film of 100 g / m ² (melting point 135 ° C.) was laminated on both sides of the mat-like material to form a laminated sheet weighing 800 g / m ² . After heating this for 3 minutes in an open at 200 ° C., it was passed through a pair of rolls with a roll gap of 1 mm and compressed.
The core was kept in an oven at 0 ° C. for 3 minutes to recover the thickness to obtain a core material made of a nonwoven fiber mat having a thickness of 7 mm.

A core material was obtained in the same manner as above except that polypropylene was used as the polyolefin for the core material.

C) Preparation of skin material A skin material made of a polyvinyl chloride sheet (0.6 mm) containing ABS resin was prepared.

D) Adhesive molding of core material and skin material First, both surfaces of the above-mentioned core material were heated at 170 ° C. with an infrared heater.
Heated for minutes. On one side of the heated core material, a cushion layer of a composite of the cushion layer and a cosmetic skin material made of non-woven fabric is arranged, and then the three-layer laminate is pressed into a press mold held at 25 ° C. (Depth 10mm, Mold 8mm,
(The radius of curvature of the concave portion was 5 mm) and pressed at a pressure of 0.2 kg / cm ² for 25 seconds to obtain a molded product.

In the attached drawings, (1) is a cushion layer,
(2) shows a skin material, (3) shows a core material, and (4) shows a press die.

Examples 2 and 3 In the preparation of the cushion layer, the blend ratio of polypropylene and polyethylene was changed, and in the preparation of the core material, the polyolefin was changed. A molded product was obtained in the same manner as in Example 1.

Performance Tests The molded products obtained in the examples and comparative examples were examined for moldability, adhesiveness, the presence or absence of wrinkles, and the presence or absence of irregularities. Table 1 shows the measurement results.

The moldability was evaluated by measuring the radius of curvature of the molded product in a portion corresponding to the radius of curvature of the concave portion of the mold of 5 mm. In Table 1, ◎ means very good, は means good, and △ means slightly good (all compared to current products).

Adhesive strength: width 25 mm, length 150 mm
Peel off the core material and the cushion layer at one end of the sample piece,
It was measured by a 180 ° peel strength test (tensile speed: 200 mm / min). In Table 1, ◎ means 100% material destruction rate, ○ means 50% material destruction rate, Δ means 0.3 kg / 25 mm or more, but interfacial peeling occurs.

The presence or absence of wrinkles was visually observed. Table 1
Medium, ◎ means very good, ○ means good, △ means a little better (all compared to current products).

The presence or absence of unevenness was visually observed. Table 1
Medium, ◎ means very good, ○ means good, △ means a little better (all compared to current products).

[0049]

[Table 1] As is clear from the above table, it is recognized that the molded articles of Examples are superior to those of Comparative Examples in all items.

[0050]

The method for bonding a core material and a skin material according to the present invention is constituted as described above, so that the core material and the skin material are bonded without using an adhesive, and the integral body is molded into a required shape. Since bonding and molding are performed at the same time, the number of steps can be reduced and the cost can be advantageously reduced, and wrinkles and irregularities do not occur.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a press molding step.

[Explanation of symbols]

 (1)… Cushion layer (2)… Skin material (3)… Core material (4)… Press type

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B60R 13/02 B29C 51/00-51/46

Claims (2)

(57) [Claims] A polypropylene resin is interposed between a core material and a skin material formed of a mat containing inorganic fibers as a main component.
0 to 70% by weight and polyethylene resin 70 to 30 weight
% And the expansion ratio is 20 times or more and the thickness is 3
A method for molding an interior material, comprising press-molding with a molding die with a cushion layer of a foam having a size of not more than 1 mm interposed. 2. The molding method according to claim 1, wherein the core material has a polyolefin-based resin layer outside a mat mainly composed of inorganic fibers.