JPH0120984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to a vacuum forming sponge sheet having a brushed appearance, more specifically, it is applied as a skin material when manufacturing automobile interior parts by vacuum forming. This invention relates to a sponge sheet that can give parts the appearance and feel of a backskin or high-quality fabric.

Prior Art and Problems to be Solved Synthetic resin sheets or sponge sheets with a natural leather-like texture are used as skin materials for automobile interior parts (for example, instrument pads, glove lids, door trims, pillars, etc.). recently,
Materials such as high-quality fabrics, backskin, and suede are being used to improve livability and marketability, as well as for superior tactile sensations such as luxury and softness, and safety such as anti-glare and cushioning properties. It's getting old. However, such materials are themselves expensive, have poor durability, and must be applied by hand, which complicates the process. Therefore, it is desired that the above objective performance be satisfied with a synthetic resin material that is relatively inexpensive and easy to process.

Conventionally, synthetic resin sheets or suede-like synthetic leather with a raised appearance have been produced by forming a foam layer by, for example, a calendaring method or paste coating, and applying heat on a heating roll or heat carrier to the surface of the foam layer. It is known that the material has a high-quality nap-like appearance and is manufactured by carrying out a heat-fusion treatment on a carrier to remove the fusion from the surface (thereby forming a sponge nap layer). When using this as a vacuum-formed skin material sheet, it has been proposed to back it with a semi-rigid thermoplastic sheet layer.

However, since the above foam layer has a structure consisting of spherical cells with a diameter of 200 to 500 μm, even if the surface is fused and removed, the molten surface inside the cells will shine and give a sparkling appearance, and furthermore, it will not be possible to stretch during vacuum forming. The foam layer is significantly stretched, resulting in an appearance that is significantly lower in quality than suede or high-quality fabrics. Furthermore, since the melting temperature for forming the raised sponge layer and the appropriate vacuum forming temperature for the backing sheet layer are in almost the same range, the surface melts during forming, resulting in a skin with an inferior appearance. In this case, a method of softening the backing sheet layer and lowering the molding temperature may be considered, but molding at low temperatures reduces the shape retention of the molded product, and also deteriorates molding processability, resulting in defects such as wrinkles and bridging. This makes stable machining difficult.

Furthermore, in order to obtain a higher-quality appearance, these sponge sheets are printed with cloud patterns or woven patterns using the usual method, but since these are printed in dots on the surface of the sponge nap layer, After molding and development, the printed pattern becomes unclear, and in areas where the development rate is high, it looks smudged or peeled off, resulting in a poor-quality appearance.

The inventors of the present invention have carried out extensive research in order to improve these drawbacks and provide a skin material that has an appearance similar to that of a high-quality backskin-like luxury fabric.
When considering the cell shape of the foam layer in order to remove surface adhesion and eliminate glitter after vacuum forming, we found that with the spherical shape, the sparkle was noticeable as mentioned above, and with the columnar shape, hairs formed in areas where the expansion rate after molding was high. It has been found that while it appears sparse, if it is shaped like an ellipse (particularly a vertically elongated ellipse), the sparkle disappears and the desired raised state can be obtained. In addition, the minor axis of such a vertically elongated ellipse is 200μ or less, preferably 100~
It was found that it is appropriate to set it to 200μ, and that if the short axis is too small, the fluffy feel will be lacking, and if it exceeds 200μ, the same defects as those of spherical and columnar shapes tend to occur. It has also been found that the above-mentioned problem of the backing sheet layer can be solved by laminating the foam layer on the non-foam sheet layer instead of providing it separately on the foam layer.

Structure and Effects of the Invention That is, the present invention provides a sponge sheet for vacuum forming comprising a thermoplastic resin foam layer (A) having a vertically elliptical cell structure and a thermoplastic resin non-foamed sheet layer (B). The resin foam layer (A) is made of polyvinyl chloride with an average degree of polymerization of 1000 to 4000, and the major axis of the vertically elongated ellipsoidal cells is 1.3 times or more the minor axis,
The short axis is 200μ or less, and the surface thereof is heat-sealed, and the thermoplastic resin non-foamed sheet layer (B) is made of polyvinyl chloride with an average degree of polymerization of 1700 to 3500. The present invention provides a sponge sheet for vacuum forming that has a nap-like appearance.

The thermoplastic resin foam layer (A) (hereinafter referred to as layer A) in the present invention is characterized by having a cell structure in the shape of an elongated ellipse. In the vertically elongated elliptical cell, the major axis is 1.3 times or more the minor axis, preferably
1.3 to 2.0 times, and the minor axis is 200μ or less, preferably
It is appropriate to set it to 100 to 200μ.
The A layer having such a cell structure usually contains a thermoplastic resin, a plasticizer (such as a phthalate ester), a metal salt stabilizer, an organic blowing agent (such as azodicarbonamide),
It is formed from a paste-sol composition (hereinafter referred to as composition A) obtained by appropriately blending a filler (such as calcium bicarbonate) and a coloring agent.

As the above thermoplastic resin, polyethylene, polypropylene, polyvinyl acetate, polyvinyl chloride (PVC), etc. can be used, but soft PVC is particularly suitable due to the durability and soft feel required for interior parts for vehicles. There is. In addition, the foam cells are controlled and the softness is achieved through paste processing.
PVC is the easiest to use. In addition, the PVC used is (average degree of polymerization) = 1000 ~
4,000 can be used, but a range of 1,500 to 3,500 is preferable in order to ensure stable formation without impairing the nap-like appearance during vacuum forming.

The thermoplastic resin non-foamed sheet layer (B) (hereinafter referred to as B layer) in the present invention constitutes the base layer of A layer and plays an important role in vacuum formability. As the B layer, a sheet with good vacuum formability such as PVC or ABS can be adopted, but the melting and foaming conditions for the A layer (usually
200 to 230°C) and to impart a soft feel to the two-layer laminate of A and B, a sheet of PVC with a high degree of polymerization (usually P = 1700 to 3500) is suitable. Layer B is usually formed from a sol composition (hereinafter referred to as composition B) obtained by suitably blending the above-mentioned high polymerization degree PVC, a plasticizer, a stabilizer, a filler, and the like.

The sponge sheet for vacuum forming according to the present invention is composed of the above-mentioned layer A and layer B, but if necessary, a normal thermoplastic resin foam layer (C) may be used as the base layer of layer B.
(hereinafter referred to as C layer) may be provided. This C layer stabilizes the vacuum forming process (improves processability, improves bridging, drawdown, improves shrinkage after molding,
In order to reduce heat unevenness in the layer, retain the mold after molding) and give a cushioned feel to the molded product, layer A,
It is applied for the purpose of preventing the migration of plasticizer from the B layer and the migration of harmful substances from the base material (especially deterioration caused by amine catalysts in urethane resin injection foaming).
It may be formed from a paste-sol composition (hereinafter referred to as composition C) obtained by appropriately blending PVC, a plasticizer, a blowing agent, a stabilizer, and the like. Note that the cell shape of the C layer is not particularly limited, and may be elliptical, spherical, or columnar.

Hereinafter, the manufacturing procedure of the sponge sheet of the present invention will be explained in detail.

First, if necessary, composition C is applied onto a carrier such as a belt or process paper and gelled.
Next, Composition B was applied and gelled, and then Composition A was sequentially applied and heat treated at 180 to 230°C for 1 to 3 minutes to form Composition A (and C as necessary).
are melted and foamed to obtain a laminated sponge sheet consisting of layer A and layer B (and layer C if necessary) from above. In this case, for the vertically elongated ellipsoidal cells of layer A, composition A is usually applied to a thickness of 0.1 to 0.5 mm, and then a stabilizer is selected so that the foaming agent is decomposed immediately before or at the same time as the sol becomes sol. This can be achieved by controlling foaming. Adopting this method of melting and foaming after coating each composition is advantageous because the work can be done easily, and problems such as delamination do not occur during subsequent molding, and processing costs are low. It is also advantageous in terms of In addition, when installing the above C layer, for example, after forming a laminated sponge sheet consisting of layers A and B, a previously prepared thermoplastic foam sheet is laminated on the B layer side, or a thermoplastic unfoamed sheet is laminated on the B layer side. A method may be adopted in which the A layer is laminated and foamed simultaneously with the unfoamed A layer.

Next, the surface of the layer A of the laminated sponge sheet is subjected to heat-fusion treatment, for example, a carrier (such as high-quality paper) heated to a temperature higher than the melting temperature is pressed onto the surface, and the surface is continuously fused and removed (stripped off). A sponge sheet of the present invention having a nap-like appearance is obtained.

Furthermore, if necessary, in order to give this sponge sheet a bag skin-like appearance or a high-quality fabric-like appearance, printing is performed by a conventional method (gravure printing, screen printing, etc.). However, in the conventional method, printing ink adheres to the tips of the fine pores on the surface of the A layer, and as a result, the print after vacuum forming often becomes sparse or cracked, which significantly impairs the appearance. Therefore, after adjusting the A layer surface to a dark color, print with a light color printing ink containing a vinyl chloride or vinyl acetate vehicle with a film elongation of 100% or more and titanium oxide of 10 to 50 PHR, preferably 20 to 40 PHR as a pigment. It was found that even after molding, the feel of high-quality fabric and the appearance of backskin were not impaired.

The sponge sheet of the present invention obtained in this manner is relatively inexpensive and can be easily processed, and by using it as a skin material for automobile interior parts, it can achieve the conventionally required comfort, product quality, and It is recognized that safety etc. can be improved.

Next, the present invention will be described in more detail with reference to Examples.

Example 1 Layer A (Composition A) Part by weight PVC (PSH26 manufactured by Kanebuchi Chemical Co., Ltd., = 1700)
…100 Plasticizer (DUP, manufactured by Shin Nihon Rika Co., Ltd.) …70 Stabilizer (Zn-Na composite liquid product) …3 Blowing agent (azodicarbonamide type) …2 Filler (calcium bicarbonate) …10 Coloring Agent...10 B layer (composition B) parts by weight PVC (P-470 manufactured by Mitsubishi Monsanto Chemical Co., Ltd.,
=3500) …100 Plasticizer (DUP) …70 Stabilizer (Ba-Zn composite liquid product) …3 Filler (calcium bicarbonate) …20 C layer (composition C) weight part PVC (PSH26) …100 Plasticizer Agent (DUP)...70 Stabilizer (Ba-Zn based composite liquid product)...3 Filler (calcium bicarbonate)...20 Blowing agent (azodicarbonamide based)...2 Composition C, Composition B and Composition A
0.2 mm, 0.5 mm, and 0.2 mm thick respectively (gelled) and immediately heated to 215℃ for 2 to 3 coats.
Melt and foam at the same time with heat treatment for 1 minute and then
A sponge sheet consisting of layer B and layer C is obtained. A carrier (high-quality paper) heated to 200 to 230°C is pressed onto the surface of layer A of the sheet, and the surface is fused and removed to obtain a sponge sheet with a total thickness of 1.5 mm and a raised appearance.

Next, white printing ink (titanium oxide 40PHR) was applied to the sponge sheet with a brushed appearance.
and dark printing ink (Dainippon Ink Chemical Co., Ltd.)
VGS manufactured by Toyo Ink Co., Ltd., T color manufactured by Toyo Ink Co., Ltd.) are toned and a high-quality textile-like print is applied using the GR method. The resulting sponge sheet is used as a skin material, and urethane resin is injected and foamed into it while vacuum forming to create an instrument pad. Moreover, a predetermined door trim or pillar can be created by vacuum forming the skin material sheet and adhering it to a core material.

Claims (1)

[Scope of Claims] 1. A sponge sheet for vacuum forming comprising a thermoplastic resin foam layer (A) having a vertically elliptical cell structure and a thermoplastic resin non-foamed sheet layer (B), wherein the thermoplastic resin foam layer ( A) is made of polyvinyl chloride with an average degree of polymerization of 1,000 to 4,000, and the major axis of the vertically elongated elliptical cells is at least 1.3 times the minor axis, and the minor axis is 200μ or less, and the surface is heat-fused. A sponge sheet for vacuum forming having a raised appearance, characterized in that the thermoplastic resin non-foamed sheet layer (B) is made of polyvinyl chloride with an average degree of polymerization of 1,700 to 3,500. 2. The sponge sheet according to item 1 above, wherein the thermoplastic resin foam layer (C) is provided as a base layer of the thermoplastic resin non-foamed sheet layer (B). 3 After heat fusion treatment, the resulting microporous surface has 20
3. The sponge sheet according to item 1 or 2, which exhibits a buckskin-like or high-grade fabric-like appearance by printing with an ink containing ~40 PHR of titanium oxide.