JPH037211B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing an interior material for an automobile, particularly a skin material for molding an instrument panel on which instruments are mounted, in the front of a driver's seat. be.

[Conventional technology and its problems]

Conventionally, instrument panels for passenger cars and the like have been made from vinyl chloride resin-based semi-rigid sheets, which have been molded and mounted using molding methods such as vacuum forming. However, in recent years, the drawbacks of these conventional instrument panels, namely the glossing phenomenon, have come to be seen as a problem. In other words, these vinyl chloride resin-based semi-rigid sheets are almost matte immediately after installation, so there is no reflection of glare during driving, allowing for safe and comfortable driving. As a result, these paints wear out over a short period of time and gradually become glossy.

The instrument panel has become shiny in the morning.
When the position of the sun is low in the evening, the sun's rays
The light is reflected by the instrument panel surface, dazzling the driver and significantly obstructing his vision.

Therefore, various efforts have been made to make these instrument panels glossy and to prevent glare from being reflected. The following methods have been proposed as such means.

(1) Place a moquette-like or carpet-like fabric with long piles on the top of the panel.

(2) After molding the instrument panel, apply matte paint using a spray method and then install it inside the vehicle.

(3) The instrument panel molding material itself is
Molding is performed using a material with a matte structure.

However, method (1) tends to cause the accumulation of dust in the room, and the dye used to dye the fibers fades in a short period of time due to sunlight shining directly through the window glass, resulting in a very poor aesthetic appearance. In addition to these problems, if the fiber layer is not treated to make it incombustible, there is also the risk of a fire caused by a cigarette or the like.

Method (2) is a so-called post-molding painting finishing method, and not only does it require a painting process to be incorporated into the final step of the instrument panel molding process, but these paints are extremely susceptible to scratches after drying. Easy to reach,
Therefore, this method is difficult to handle.

In method (3), for example, a synthetic resin foam layer is provided on the top surface of a conventional semi-rigid sheet material, and the thin layer on the surface is removed by buffing or slicing to expose the porous structure layer. It is said that this porous structure layer is effective in preventing the reflection of glare. However, when this porous structure surface material is a continuous porous material, the cell wall surface is a closed cell porous material, and when it is a closed cell porous material, the bottom surface in particular has a very unpleasant flickering effect due to the stretching action during vacuum forming. Since gloss is generated, it is essential to apply a matte paint to the inner surface of the porous structure. However, these conventional porous structure surface materials are easily attacked by the solvent contained in the paint, so the paint cannot be applied thickly and a sufficient fade effect cannot be obtained. Therefore, by using water-soluble erasing paint,
It is thought that this problem can be solved, but in this case, a large amount of water enters the porous structure, so it takes a long time to dry, and when heated to speed up drying, the surface of the porous structure may be deformed or broken. Necessary and troublesome unevenness will occur.

[The problem that the problem is trying to solve]

In view of this background, the inventors of the present invention have conducted extensive research and have followed the method described in (3) above, but even when stretched during vacuum forming, the film does not produce any strange flickering luster.
Moreover, it is an object of the present invention to provide a skin material for molding having a porous structure that does not swell or corrode even when conventional solvent-based surface treatment agents are used.

[Means for solving problems]

A means to solve the problem is to use a mixed resin of a normal paste-grade polyvinyl chloride resin and an isocyanate-crosslinkable polyvinyl chloride resin as the main component, and to add the isocyanate-crosslinkable paste-grade polyvinyl chloride resin to the carrier. A foamable plastisol layer is coated by adding the isocyanate necessary for crosslinking, an appropriate amount of a plasticizer, a stabilizer, a blowing agent, and a pigment if necessary, and the foamable plastisol layer is heated to gel, and then the upper surface is coated. A backing layer made of a crosslinkable plastisol obtained by removing the foaming agent from the foamable plastisol is applied to the foam, and then these are introduced into a foaming furnace to gel and crosslink the backing layer, at the same time foaming the foamable plastisol layer, and after cooling. The skin material is produced by peeling off the carrier and simultaneously slicing and removing the thin skin of the foam layer that was in contact with the carrier, then applying an erasable paint to the surface of the foam layer and drying it.

〔Example〕

The isocyanate-crosslinkable paste-forming polyvinyl chloride resin used in the production method of the present invention is a hydroxyl group-modified paste-forming resin, and a typical example thereof is Vinica P100A manufactured by Mitsubishi Monsanto Chemical.
The mixing ratio of this isocyanate crosslinking paste resin and ordinary paste polyvinyl chloride resin is as follows:
This is an important factor in determining the foaming state of the skin material for molding.
A range of 40 to 30 parts by weight of isocyanate crosslinkable paste resin is suitable. If the mixing ratio of the isocyanate crosslinking paste resin is low, the degree of crosslinking after foaming will be low, and when a surface treatment agent is applied, the cell walls of the foamed cells will be attacked or swelled by the solvent contained in the paint. Furthermore, the most important factor, the vertical elongation phenomenon of foamed cells, does not occur. On the other hand, if the mixing ratio of the isocyanate crosslinkable paste resin is too high, crosslinking will be excessive during heating and foaming, and a sufficient expansion ratio (for example, 4 to 6 times foaming) will not be obtained, resulting in a matte surface. The foam cells atrophy and do not become an excellent molding skin material.
Furthermore, vacuum formability is also impaired.

Therefore, the mixing ratio of these two types of paste resins must be said to be an extremely important factor. However, when using Vinica P-100A manufactured by Mitsubishi Monsanto Chemical, as mentioned above, 40 to 30 parts by weight is suitable compared to 60 to 70 parts by weight of the usual paste resin, but the degree of hydroxyl modification has changed. It is natural that this mixing ratio will change slightly in such cases, and it goes without saying that the optimum mixing ratio in that case should be determined by experiment.

The isocyanate used in the method of the present invention should basically be an isocyanate suitable for the crosslinkable resin, but vinylcar P-
In the case of 100A, thermosetting polyisocyanate manufactured by Takeda Pharmaceutical Co., Ltd., specifically Takenate B815N, is considered optimal, and the amount used is selected within the range of 5 to 15 PHR per 100 parts by weight of the crosslinkable resin.

The other ingredients that make up the plastisol, such as plasticizers, stabilizers, fillers, and pigments, should be used according to conventional plastisol compounding techniques, but the blowing agent in the first step should be a pyrolyzable foam such as azodicarbonamide. Gas-generating so-called chemical blowing agents are suitable.

In principle, a release paper is used as the carrier 1 in the first step, but from the viewpoint of the purpose of the present invention, that is, a method for producing a skin material for molding, it does not necessarily have to be a release paper, and plastisol can be applied. The carrier may be, for example, a non-releasing paper 1' such as kraft paper as shown in FIG. In any case, the above-mentioned foamable plastisol is applied onto these carriers 1 to a thickness of 0.4 to 0.6 mm by a method such as a doctor roll method.
It is gelled by passing it through a heating furnace at around ℃. At this stage, the foaming agent does not decompose and the foamable plastisol layer 2
is a liquid sol that solidifies into a smooth sheet.

Next, a non-foamed layer plastisol as a backing layer 3 is applied onto the foamed plastisol gel sheet 2, but this backing layer 3 is a cross-linked material obtained by removing only the foaming agent from the foamable plastisol used in the first step. using plastic plastisol. That is, the main component is a mixed resin of a normal paste polyvinyl chloride resin and an isocyanate crosslinkable polyvinyl chloride resin,
A plastisol is prepared by adding isocyanate as a crosslinking agent, a plasticizer as a necessary compounding agent, a stabilizer, and pigments and fillers as necessary.
Apply to a thickness of 0.2 to 0.5 mm. In this case, if the crosslinking and gelation of the backing layer is faster than the crosslinking and foaming of the foam layer,
The film of the backing layer has sufficient gel strength against expansion during the foaming process, so surface roughness during foaming can be prevented.

For this reason, it is preferable that the mixing ratio of the isocyanate crosslinked paste resin in the backing layer is higher than that in the foam layer;
~45 parts by weight is suitable.

After applying the backing layer 3 in this way, the temperature is 220-230℃.
When the foaming plastisol layer 2 is introduced into a heated foaming furnace and heated for about 2 minutes, the foamable plastisol layer 2 expands 5 to 6 times to become a foamed layer 2' having longitudinal cell pores, and the backing layer 3 is loosely cross-linked as shown in FIG. It exhibits a sheet state with a smooth surface.

In the case of a backing layer using a plastisol made of a normal paste resin that does not use an isocyanate crosslinkable paste resin, it is not possible to suppress roughness during foaming of the expandable plastisol at this foaming stage, and the backing layer has a smooth surface. Instead of forming layers, countless shrinkage wrinkles and wavy wrinkles occur, resulting in all products being defective. Here, the superiority of the present invention using a crosslinkable plastisol for the backing layer will be understood.

These foam sheets are passed through a cooling device, and after being sufficiently cooled, they are placed on guide rolls as shown in FIG.
The releasable carrier 1 is peeled off from the foam sheet surface through the . When a non-releasable carrier 1' is used, only cooling is required.

In the case of a foam sheet using the releasable carrier 1, the surface of the foam sheet after the releasable carrier 1 is peeled off has the following properties:
A thin skin-like film 2'' has been formed due to contact with the releasable carrier, so it is necessary to buff it or remove it with the peeling blade 5.
Excise by. After removing the thin film 2'', the surface of the foam sheet becomes a beautiful surface with many cell pores of vertically elongated cells.However, the surface of the foam sheet obtained is slightly faded with a gloss of around 10% at 60°. Although the surface is smooth, it is too glossy to be used as an instrument panel surface, so surface treatment with a matte paint (not shown) is required.

Suitable matte paints used for surface treatment are vinyl chloride resin, acrylic resin, or solvent-based paints in which a fader is mixed and dispersed in a mixed resin solution of vinyl chloride resin and acrylic resin. As a method, in addition to thick coating printing using a gravure printing device, methods such as a spray method are used.

When a non-releasable carrier 1' is used, immediately after cooling the foam sheet with a cooling roll as shown in FIG. , and finish in the same way as above.

After applying the matte paint, the foam sheet surface is
At 60° gloss, it becomes a very good faded surface of 2 to 3%, and even after applying it to a vacuum forming machine to form an instrument panel, this value remains 4 to 5%.
With very little gloss, an extremely excellent matte instrument panel can be obtained.

As an application example of the method of the present invention, it is also possible to laminate a semi-rigid sheet 6 on the back surface of the backing layer 3 as shown in FIG. This results in a molded product with excellent wearability.

Next, specific aspects of the present invention will be explained.

(1) Application and gelation of expandable plastisol layer Polyvinyl chloride resin for compounded isocyanate crosslinkable paste *1 35 parts by weight Polyvinyl chloride resin for general paste *2
65 〃 Plasticizer D-11 30 〃 〃 DOP 30 〃 Stabilizer (Zn-Ca type) 3.0 〃 Foaming agent 6.0 〃 Thermosetting polyisocyanate *3
3.0 〃 Pigment Appropriate amount *1 Vinicar P-100A manufactured by Mitsubishi Sansanto Kasei Co., Ltd. = 1300 *2 Vinicar R-1069 manufactured by Mitsubishi Sansanto Kasei Co., Ltd. = 1800 *3 Takenate B815N manufactured by Takeda Pharmaceutical Co., Ltd. The mixture was kneaded with a blade kneader to obtain plastisol with a viscosity of 5000 to 5500 CPS. Apply this plastisol to a thickness of 0.5 mm on release paper using a doctor roll coating device,
The mixture is introduced into a heating furnace at ℃ and heated to gel. The foamable plastisol layer solidified into a sheet with a smooth surface.

(2) Coating and foaming of backing layer Formulation 2 Polyvinyl chloride resin for isocyanate crosslinking paste 50 parts by weight Polyvinyl chloride resin for general paste *4
50 〃 Plasticizer D-11 35 parts by weight 〃 DOP 30 〃 Thermosetting polyisocyanate 3.0 〃 Stabilizer (Be-Zn type) 3.0 〃 Filler (light calcium carbonate) 10 〃 Pigment Appropriate amount *4 Mitsubishi Monsanto Chemical Co., Ltd. ) Vinica P-510 = 1500 The above mixture was kneaded in the same manner as in (1) above,
A cross-linked plastisol with a viscosity of 11.000 CPS, (1)
on the gelled layer of expandable plastisol obtained in
It was coated to a thickness of 0.3 mm and immediately introduced into a heating and foaming furnace heated to 220°C for heating and foaming.

The expandable plastisol layer was expanded approximately five times to become a foam layer, and the crosslinkable plastisol layer was crosslinked to become a backing layer with a smooth surface.

(3) Peeling of carrier and removal of thin film After cooling the release paper and foam sheet (laminated sheet of foam layer and backing layer), the release paper was peeled from the foam sheet via a guide roll. The resulting foam sheet had a thickness of 2.8-3.0 mm.

Next, the foam sheet was passed through a skin sifting machine, and the thin skin-like film portion that was in contact with the release paper was removed using a skin sifting blade to obtain a foam sheet with an average thickness of 2.0 mm.

This foam sheet had a semi-matte surface gloss with a reflectance of around 10% when measured at 60 degrees with a surface gloss meter.

(4) Surface treatment agent Matte paint Leather Hit LG328 30 parts by weight 〃 LM415 70 〃 Solvent MEK Appropriate amount The paint with the above composition was put into a gravure printing machine, and a doctor blade was applied between a 60-mesh metal pick-up roll and a back-up rubber roll. It was applied to the surface of the foam sheet using the so-called jab coating method, which does not use any adhesive, and dried for 1.5 minutes in a hot air drying oven at 100°C.
The resulting foamed sheet had a matte surface gloss of 2 to 3% at 60 degree gloss, and was an extremely beautiful skin material for molding.

When molded using this skin material on an actual instrument panel vacuum forming line, the result was an instrument panel with a maximum gloss of 6% and an average gloss of 4 to 5%, with almost no glare reflection. was gotten.

[Comparative example]

A plastisol was prepared by replacing the entire amount of the incyanate crosslinkable paste polyvinyl chloride resin in Formulation 1 with a general paste resin, changing the amount of plasticizer to 27 parts each, and excluding the thermosetting polyisocyanate, and using the same method as in Example. A gelled sheet layer of expandable plastisol was obtained by the method.

Next, the entire amount of the isocyanate crosslinkable paste polyvinyl chloride resin in Formulation 2 in Example was replaced with a general paste resin, and the amount of plasticizer was changed to D.
A plastisol containing 30 parts of -11 and 25 parts of DOP was prepared, and a foamed sheet was obtained in the same manner as in the example.

The surface of the foam sheet obtained in this comparative example was
It had a gloss level of 18% under 60 degree light, which was considerably higher than that of the foam sheet surface of the example.

Next, when the surface was treated with the same matte agent as in the example, a low gloss surface with a surface gloss of 3 to 4% was obtained, but the foamed cells were deformed by the solvent and had severe irregularities. It was in a state that it could not be used as a skin material for molding.

Comparing the Examples and Comparative Examples above, the foamed cells of the skin material of the Examples are vertically elongated, and the bottoms of the foamed cells are deep, so when the surface is treated with a matte paint, the inside of the bottoms can be reached. Even if the paint enters and is stretched by vacuum forming, it can fully follow the stretching and there is no flickering gloss due to paint film breakage, whereas in the comparative example, the foamed cells are horizontally long and the bottom of the cells is shallow. Therefore, it cannot follow the stretching during vacuum forming, and the coating film breaks down, resulting in a very high occurrence of flickering gloss.

〔Effect of the invention〕

The first feature of the present invention is that the isocyanate crosslinkable polyvinyl chloride resin for pastes is used in the foam layer in a mixture with the polyvinyl chloride resin for general pastes, so that gentle crosslinking is performed by heating during foaming.
As the foam grows in the thickness direction, the foam cells become vertically elongated and the bottom of the cell becomes deep. Therefore, when surface treatment is performed using a matte paint, the paint penetrates to the deep bottom of the cell. For that reason,
Even if stretching is applied during vacuum forming, the stretching can be fully followed, so there is no flickering or gloss due to paint film breakage, and an extremely excellent matte instrument panel can be obtained.

The second feature of the present invention is that, as described above, the isocyanate crosslinkable paste resin is used in the foam layer, so the foam cell walls are crosslinked and become a low gloss state, so that the effect of the matte paint is very effective. At the same time, since it is not attacked by the solvent contained in the paint, a sufficient matte treatment is possible.

The third feature of the present invention is that the backing layer uses a crosslinkable plastisol made from a combination of an isocyanate crosslinkable polyvinyl chloride resin and a one-component paste resin, so that gentle crosslinking is achieved by heating during foaming. Therefore, roughening of the surface of the expandable plastisol layer during foaming can be suppressed, and a backing layer with a smooth surface can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIGS. 1 to 4 are sectional views showing the order of steps, and FIGS. 5 and 6 are sectional views of other embodiments. 1′
2 is a carrier, 2 is an expandable plastisol layer, 2' is a foam layer, 2'' is a thin skin portion, and 3 is a backing layer.

Claims (1)

[Claims] 1. A method for producing a skin material for molding, characterized by comprising the following steps. 1st step: A method for producing a skin material for molding, characterized by comprising the following steps: 1. Process of manufacturing a normal polyvinyl chloride resin for pastes and a polyvinyl chloride resin for isocyanate-crosslinkable pastes. Mixing ratio: 60-70 parts by weight: 40-30
The main component is parts by weight of a mixed resin, to which are added the isocyanate necessary for crosslinking the vinyl chloride resin for the isocyanate crosslinkable paste, an appropriate amount of a plasticizer, a stabilizer, a blowing agent, and, if necessary, a pigment. Step of applying the foamable plastisol layer onto the carrier; 2nd step: After heating the foamable plastisol layer in the 1st step to gel it, the foaming agent is removed from the foamable plastisol in the 1st step on the top surface. 3rd step of applying a backing layer made of crosslinkable plastisol in which the mixing ratio of ordinary polyvinyl chloride resin for paste and polyvinyl chloride resin for isocyanate crosslinkable paste is 45 to 55 parts by weight: 55 to 45 parts by weight; Step: Next, these are introduced into a foaming furnace to gel and crosslink the backing layer, and at the same time foam the expandable plastisol layer.Fourth step: After cooling the foam sheet from the third step, the carrier is peeled off. At the same time or without peeling off the carrier, a step of slicing and removing the thin skin part of the foam layer that was in contact with the carrier; Fifth step: After removing the thin skin part, the surface of the foam layer is The process of applying and drying paint.