JP3352553B2 - Manufacturing method of interior materials - 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 producing an interior material having excellent adhesiveness, which is mainly used as an interior material for doors and ceilings of vehicles and the like.

[0002]

2. Description of the Related Art A foam made of a polypropylene resin has excellent heat resistance and a moderate cushioning property, and is widely used as an interior material in which a surface material such as a vinyl chloride resin sheet is laminated for door and ceiling interiors of vehicles and the like. It is used. Since this material itself has poor rigidity as an interior material, it is used as a composite material in which a synthetic resin plate such as an ABS resin is used as a core material and a foam surface is bonded to the core material, and the composite material is shaped by vacuum molding or the like.

[0003] In order to bond a polypropylene-based resin foam to a core material to form a composite material, a primer layer is provided on the foam surface in order to enhance adhesiveness, and the core material is laminated to the core material via the primer layer with an adhesive.

[0004] As a method for producing the foam, there are a horizontal foaming method in which an unfoamed sheet is foamed while being fed in the horizontal direction, and a vertical foaming method in which the foam is foamed while hanging down in the vertical direction.
Since the foam produced by the horizontal foaming method does not receive tension in the length direction, fine irregularities are formed on the surface. The irregularities are JI
The average roughness (Ra) defined in SB0601 is about 1
1 to 15 μm.

[0005] However, since the foam produced by the vertical foaming method is produced while receiving tension in the longitudinal direction, the surface unevenness is smaller than that of the horizontal foamed product, and the average roughness is 1%.
１３13 μm.

[0006]

With the above average roughness of the horizontal foamed article, the anchoring property to the primer layer, that is, the adhesiveness to the primer layer is good without any particular surface treatment. However, vertical foamed products having better surface smoothness than horizontal foamed products are superior in secondary workability such as laminating with other materials to form a composite, so vertical foamed products may be selected . In the vertical foamed product, the average roughness of the surface is small, so the anchoring property to the primer layer is poor, and since it is made of a polypropylene resin, the surface activity is low and the wettability to the primer layer is inferior. Adhesiveness cannot be obtained.

In order to apply the primer to the surface of the foam and to dry it, it is necessary to pass through a drying oven having a temperature of 60 to 100 ° C. and a length of 5 to 10 m. When using a vertical foam product, if there is an insufficiently dried part in the formation of such a primer layer, the obtained interior material is rolled up or stacked, and the primer layer is attached to the vinyl chloride resin sheet on the back The primer layer is transferred to the vinyl chloride resin sheet by adhesion and blocking, and the foam surface at the portion where the primer layer is transferred is in a state without the primer layer.

When the above interior material is laminated on a core material,
The portion without the primer layer has poor adhesion, and when this is formed by vacuum molding or the like, the surface of the vinyl chloride resin sheet, which becomes the surface, partially swells, becomes unsightly, and the peeling gradually increases.

[0009] Kraft paper or polyethylene film is sandwiched as interleaving paper in order to prevent transfer when the primer layer on the foam surface is overlaid on the vinyl chloride resin sheet surface. Is required as an auxiliary material, and it takes time to sandwich or remove the material between the interior materials.

On the other hand, the amount of the adhesive for laminating the foam to the core material depends on the conditions such as equipment conditions for drying the foam, the drying time, and the like.
It is preferable that the amount is as small as possible from the viewpoint of cost, solvent recovery and the like.

The present invention solves the above-mentioned conventional problems, and does not cause blocking due to transfer of the primer layer to the vinyl chloride resin sheet on the back surface even when the interior material is wound up or overlaid. An object of the present invention is to provide a method for producing an interior material that requires a small amount and has excellent adhesion to a core material.

[0012]

According to the present invention, there is provided a method for producing an interior material, comprising a laminated foam comprising a polyvinyl chloride resin sheet laminated on one surface of a foam made of a polypropylene resin and having a surface roughness of 3 to 10 μm. Is subjected to a corona discharge treatment so that the surface tension becomes 34 dyn / cm or more, a primer is applied to the corona discharge treated surface and dried.

The polypropylene resin used in the present invention includes polypropylene and a mixture of polypropylene and an ethylene resin such as polyethylene, linear low-density polyethylene, and ethylene-vinyl acetate copolymer. The above mixing ratio is such that the polypropylene is 40 to 10
It is preferable that the content of the ethylene-based resin is in the range of 60 to 0% by weight. Further, the expansion ratio of the foam is preferably 15 to 30 times in terms of strength and cushioning properties,
Those having a thickness of 1 to 4 mm are preferably used.

In the present invention, a foam made of the above polypropylene resin is produced by a vertical foaming method,
The average surface roughness (Ra) specified in B0601 is 3
One having a diameter of 10 to 10 μm is used. If the average roughness is less than 3 μm, sufficient adhesive strength cannot be obtained even if surface activation treatment is performed, and if it exceeds 10 μm, a large amount of adhesive is required, which is not preferable. A vinyl chloride resin sheet serving as a surface material is previously laminated on one surface of the foam. The vinyl chloride resin sheet preferably has a thickness of 0.4 to 0.7 mm in terms of flexibility, workability, and the like as laminated with the foam.
The method of laminating a vinyl chloride resin sheet is a method using an adhesive, a method using extrusion lamination through a molten resin, and the like.
Conventional methods can be employed.

Although corona discharge treatment is generally performed to enhance the adhesiveness of the exposed foam surface to be bonded to the core material, a sufficient surface is required for a vertical foam having the above average roughness. In order to obtain wettability, it is necessary to increase the surface tension to 34 dyn / cm or more by corona discharge treatment. When the surface tension is less than 34 dyn / cm, the anchoring property of the foam to the primer layer is insufficient, and the interface tends to peel off.

If the surface of the foam is subjected to a corona discharge treatment to have a surface tension of 34 dyn / cm or more, functional groups such as ether, ketone, acid and ester are generated on the surface, so that the adhesion to the primer layer is remarkable. improves. and,
Due to the corona discharge treatment, fine irregularities are newly generated on the foam surface, and the foam surface exerts a strong anchoring property with respect to the primer layer formed by applying and drying the irregular surface. on the other hand,
When the same interior material is superimposed on this, the back surface, that is, the surface of the vinyl chloride resin sheet and the superposed primer layer are in point contact, so that even if they adhere, they do not enter a blocking state and can be easily peeled off.

The primer applied to the corona discharge treated surface is a solution obtained by dissolving chloroprene rubber, acrylic resin, urethane resin or the like as a main component in a solvent such as ether or toluene. m ²
Apply so that Roll coating method such as gravure roll, reverse roll, kiss roll,
A commonly used device such as an air knife coater may be used.

If the applied primer is dried at a temperature of 60 to 100 ° C. as in the past, the primer is passed through a drying oven having a length of about 3 m to have a surface roughness of 11 to 15 μm.
The same adhesive strength as that of the horizontal foamed surface is obtained. That is, it was found that the length of the drying oven was significantly shorter than that of the conventional 5 to 10 m even when the laminated foam coated with the primer was conveyed at the same traveling speed as the conventional one.

[0019]

In the present invention, it is made of a polypropylene resin,
By subjecting a foam surface having an average roughness of 3 to 10 μm to a corona discharge treatment so that the surface tension becomes 34 dyn / cm or more, ether, ketone,
A functional group such as an acid or an ester is generated, the activity is increased, and the wettability is improved. At the same time, fine irregularities are generated on the foam surface by the corona discharge treatment, so that the adhesion to the primer layer is remarkably improved.

Thus, the foam surface and the primer layer formed by coating and drying have an average surface roughness of 11 to 11.
It exhibits the same strong anchoring property as to the foam surface of 15 μm. On the other hand, if the same interior material is placed on top of this, the back surface, that is, the surface of the vinyl chloride resin sheet and the primer layer are in point contact, so that even if they adhere, they do not enter a blocking state and can be easily peeled off.

[0021]

EXAMPLES Next, examples of the method for producing an interior material according to the present invention will be described. (Examples 1 to 8) Ethylene content 4% by weight, MI = 2.0
, 40 parts by weight of LLDPE having a density of 0.920 and MI = 2.0, 5 parts by weight of azodicarbonamide as a foaming agent, and 0.1 part of a phenolic antioxidant as a stabilizer. 5 parts by weight and 2 parts by weight of divinylbenzene as a crosslinking accelerator were added and mixed, and supplied to a twin-screw extruder to form a sheet.

After irradiating the sheet with an electron beam at 5 Mrad, the sheet was foamed in a vertical foaming furnace, and the surface temperature was 60 ° C.
15mm expansion ratio, thickness 2mm
Was obtained and the surface roughness was measured according to JIS B0601. The surface of the obtained foam sheet was subjected to corona discharge treatment so as to have the surface tension shown in Table 1.

A 30% NV solution of chloroprene dissolved in toluene as a primer was applied to the above-mentioned corona discharge treated surface with a reverse coater so as to have a thickness of 3 μm after drying, and a drying oven of 3 m in length heated to 80 ° C. For 2 seconds to obtain the interior materials of Examples 1 to 8. In addition, the application amount was adjusted by the clearance of the reverse coater.

On the other hand, in order to check the required amount of the adhesive, the laminate bonded to the vinyl chloride resin sheet was cut to a width of 25 mm while changing the amount of the adhesive applied, and the JIS K 6767 was used.
The minimum required amount of adhesive after drying for peeling the foam and destroying the material was determined in accordance with the above.

(Comparative Examples 1 to 6) As a comparative example, each interior material was treated in the same manner as in Examples 1 to 8 except that a corona discharge treatment was performed so as to have the surface tension shown in Table 2 and the amount of the adhesive was used. I got

Performance Evaluation Each of the interior materials of each of the Examples and Comparative Examples was stacked two by two.
The state of occurrence of blocking after 24 hours in each of ovens at 60 ° C., 80 ° C., and 100 ° C. under a load of 1 kg was observed, and expressed by the following evaluation criteria. The results are shown in Tables 1 and 2. ◎: Not generated at all ○: Generated very slightly △: Generated very much ×: Generated very often-: Not measured *: Due to small surface roughness, surface tension was increased to 50 dyn / cm by corona discharge treatment. And the amount of adhesive is 24
Even at g / m ² , it was not possible to determine the amount of adhesive that caused interface separation and material destruction.

[0027]

[Table 1]

[0028]

[Table 2]

As is clear from Tables 1 and 2, the interior materials obtained in Examples 1 to 8 were provided with a primer layer on the surface of the foam having a surface tension of 34 dyn / cm or more by the corona discharge treated surface. No blocking occurred with the vinyl chloride resin sheet. On the other hand, in the case of Comparative Examples 1 to 4, since the surface tension of the foam was 33 dyn / cm or less, the adhesion to the primer layer was poor and blocking occurred. Further, in the case of Comparative Example 5, the surface roughness was 1 μm, so that a sufficient adhesive force could not be obtained even when the surface tension was set to 50 dyn / cm. In the case of Comparative Example 6, the surface roughness was 13 μm, so that a large amount was obtained. Adhesive amount was required.

[0030]

The method for producing an interior material according to the present invention has the above-mentioned structure. Since the corona discharge treatment is performed so that the surface tension becomes 34 dyn / cm, a functional group is generated on the surface of the foam, and the foam and the primer are formed. Adhesion with the layer is determined by an average surface roughness of 11
An adhesion equivalent to a foam having a thickness of up to 15 μm is obtained.

Further, since the surface of the vinyl chloride resin sheet and the primer layer are in point contact with each other due to fine irregularities generated by the corona discharge treatment, even if they adhere, they do not enter a blocking state and can be easily peeled off. Therefore, even if the interior material is wound up or overlaid, the interior of the interior material is excellent in adhesiveness to the core material without causing the blocking of the primer layer transferred to the back vinyl chloride resin sheet.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI B32B 27/30 101 B32B 27/30 101 27/32 27/32 C 31/12 31/12 // C08L 23:10 C08L 23: Ten

Claims (1)

(57) [Claims] 1 to 3 comprising a polypropylene resin
A corona discharge treatment is applied to the exposed foam surface of the laminated foam in which a vinyl chloride resin sheet is laminated on one surface of the foam having a surface roughness of μm so that the surface tension is 34 dyn / cm or more. A method for producing an interior material, comprising applying a primer to an electric discharge treated surface and drying.