JPH0327374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for decorating polyurethane resin bumpers for automobiles.

(Prior art) Currently, various types of shock absorbing type bumpers have been devised and widely used as bumpers for automobiles for safety reasons.In particular, from the point of view of weight reduction, they are made of resin with elastic function in many countries. Bumpers have been developed, and the use of polyurethane bumpers is increasing in Japan.

Molded resin bumpers typically have a distinctive coloration, such as black, due to fillers such as carbon black or other additives that are incorporated to improve physical performance. Therefore, from the viewpoint of the overall aesthetic appearance of the automobile, it has been necessary to paint the surface of the bumper made of resin such as polyurethane with a paint of a desired color in order to match the color of the vehicle body.

(Problem to be solved by the invention) However, in this method of painting with paint, the mold release agent adhering to the polyurethane resin bumper is cleaned with solvent vapor, and then the solvent is removed, and then the primer is applied. However, it is necessary to dry it further, then apply a top coat, and then perform baking drying, which not only requires a large number of work steps, advanced painting techniques, and a considerable number of workers, but also makes it difficult to use the plastic bumper. Since a special paint is used from the viewpoint of adhesion, there is a problem in that the paint itself is expensive. In addition, the solvent-based paints that have traditionally been used often evaporate, so
There was a problem in that a considerable amount of capital investment was required for the painting booth, disposal, and waste liquid treatment equipment.

(Means for Solving the Problems) The present invention has been made in view of the above points, and
The purpose is to eliminate the above-mentioned problems and to provide polyurethane resin bumpers with colors or patterns that match the vehicle body color in an extremely economical manner. Bumper on the back, nitrile content 10
~40 mol% acrylonitrile-butadiene rubber
70 to 200 parts by weight of a modified phenolic resin having a softening point of 60 to 150°C per 100 parts by weight and adhesion imparting resin 2
Covering with a colored or patterned polyvinyl chloride decorative sheet coated with a heat-activated adhesive, which is a composition comprising ~100 parts by weight, and sucking the decorative sheet onto a polyurethane resin bumper under heating. and/or a method for decorating a bumper made of polyurethane resin by applying pressure and adhering to the surface of the bumper via a heat-activated adhesive.

(Function) The polyurethane bumper used in the present invention has relatively high adhesiveness and high impact resistance, so it is highly effective. Therefore, there is no need to particularly limit the polyurethane compounding method and molding method described above, and polyurethane bumper molded products that have been conventionally painted can be used as they are in the method of the present invention.

The decorative sheet made of polyvinyl chloride must have a color or pattern that matches the specified car body, and in order to ensure good adhesion, it is heated and suctioned and/or pressurized to form a bumper molded product. It needs to be attached to the curved surface using heat-activated adhesive. Therefore, the physical properties of this decorative sheet are:
It must be highly pigmented and have adequate thermoplasticity and compatibility with heat-activated adhesives. Also,
From the viewpoint of aestheticizing the necessary surfaces of the bumper, the decorative sheet must also have sufficient weather resistance. The method for coloring the decorative sheet includes a method of blending a pigment into the sheet base, a method of pre-printing on the surface of the sheet with a printing machine, etc., but is not particularly limited.

As a decorative sheet with such characteristics,
0 to 50 parts of plasticizer per 100 parts by weight of polyvinyl chloride
Thickness 20 parts by weight and containing appropriate amount of ultraviolet absorber
Pigmented polyvinyl chloride sheets of ~500 microns, preferably 20-250 microns, are most desirable.

Examples of plasticizers include esters such as dibutyl phthalate, dioctyl fluorthalate, dioctyl isophthalate, dioctyl sepacate, and dioctyl adipate, epoxidized vegetable fats such as epoxidized soybean oil, and polyester plasticizers. 0 to 50 parts by weight, preferably
10-35 parts by weight are used. Examples of ultraviolet absorbers include benzophenone derivatives, phenyl salicylate, resorcinol esters, benzotriazole derivatives, etc., and are used in an amount of 0.05 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of polyvinyl chloride. Ru. Furthermore, a predetermined amount of stabilizers and organic stabilizing aids such as lead salt-based, metal-based stabilizers, and organic tin-based stabilizers are also blended.

As for the method of attaching the decorative sheet to the polyurethane resin bumper, as a result of various studies, we found that air bubbles etc. can be interposed on the entire front side of the polyurethane resin bumper, which has a complex curved surface, by one application operation. It has been found that the most effective method for adhering the decorative sheet tightly is to apply a heat-activated adhesive to the back surface of the decorative sheet in advance, and then absorb it under heat, pressurize it, or use a combination of both.

The heat-activated adhesive to be applied to the back side of the decorative sheet not only has good adhesion to the decorative sheet, but also activates the adhesive by heating it to the plasticizing temperature of the decorative sheet, making it possible to make polyurethane resin. It must be able to adhere closely to the bumper and sufficiently hold the decorative sheet adhered to the curved surface when heat is removed. Furthermore, after adhesion, it must have weather resistance for a long period of time and must be able to sufficiently maintain its adhesive function in a practical temperature range. What is the heat-activated adhesive described here?
This means that the adhesive is activated by applying a certain amount of thermal energy or more, and exhibits its ability to bond adherends. Therefore, the presence or absence of a curing reaction by heating is not particularly limited. The decorative sheet and the adhesive must be flexible enough to follow the curved shape of the polyurethane resin bumper at a predetermined heating temperature after being brought into contact with the polyurethane resin bumper.

The heat-activated adhesive applied to the back side of such a decorative sheet is acrylonitrile-butadiene rubber (NBR) 100 with a nitrile content of 10 to 40 mol%.
70 to 200 parts by weight of a modified phenolic resin having a softening point of 60 to 150°C and 2 to 2 parts by weight of an adhesion-imparting resin
A composition containing 100 parts by weight shows good properties. A more preferable composition of the adhesive is:
80 to 80 parts of the above phenolic resin per 100 parts by weight of NBR
150 parts by weight and 10 to 60 parts by weight of the adhesion-imparting resin. The adhesion-imparting resins include chlorinated rubber, ketone resins, natural rosins, polymerized, partially hydrogenated, maleated or limed modified rosins, derivatives of natural or modified rosins, polyterpene resins, and _C9 residues in naphtha cracked oil. These include aromatic hydrocarbon resins, dicyclopentadiene resins, coumaron-indene resins, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer resins, etc. Two or more types are used in combination.

Application of these adhesives to the back side of the decorative sheet is as follows:
The adhesive is applied in advance by a solution coating method or a hot melt coating method depending on the physical properties of the adhesive.

(Example) Next, with reference to the drawings, a method of applying and painting a decorative sheet whose back surface is coated with a heat-activated adhesive to a polyurethane resin bumper will be described.

As shown in Figs. 1 to 3, the bumper 1 made of polyurethane resin is first molded into a predetermined shape, and since a mold release agent is usually attached to the surface, the surface is coated with a solvent such as trichlorethylene or its vapor. The mold release agent is removed by washing, and then the solvent is removed by a conventional method, and then a primer treatment is performed if necessary. The primer formulation is selected depending on the adhesion of the resin bumper and the heat-activated adhesive used. When a primer is used in this way, after heating at room temperature or under heat, and when not using a primer, after removing the solvent as described above, the heating suction device 2 is heated as shown in FIG. It is placed on a suction section 4 with a number of suction holes 3 connected to an absorption device, for example a vacuum pump (not shown). Next, the bumper 1 is covered with a decorative sheet 5 coated with adhesive so that the adhesive-applied surface faces the bumper 1 side, and further, in order to improve the familiarity between the decorative sheet 5 and the polyurethane resin bumper 1, The decorative sheet 5 is covered with an open-cell polyurethane foam sheet 6.

Then, when a suction device (not shown) is activated,
The decorative sheet 5 is sucked into a state in which it conforms to the surface shape of the polyurethane resin bumper 1 and covers it as shown in FIG. Furthermore, when an ultraviolet heater 8 equipped with a silicone gum sheet 7 for compression is placed and pressed under heating, the thermoplastic resin decorative sheet 5 is thermally deformed and the heat-activated adhesive is activated, thereby causing the resin bumper 1. It comes into close contact along the curved surface of 1. Then, when the heater 8 is removed, the decorative sheet 5 is stuck to the front side of the resin bumper 1, as shown in FIG. By removing this adhesive and cutting off the extra decorative sheet 5,
As shown in FIGS. 4 and 5, a finished product 10 is obtained after a decorative sheet 5 having a desired color or pattern is adhered to the surface of a polyurethane resin bumper 1 via a heat-activated adhesive layer 9.

Next, the present invention will be explained in more detail by giving examples.

Example A polyvinyl chloride sheet with a thickness of 100 microns was used as a blue pigment by blending 20 parts by weight of dioctyl phthalate as a plasticizer and 2 parts by weight of phenyl salicylate as an ultraviolet absorber with respect to 100 parts by weight of polyvinyl chloride. A decorative sheet colored with phthalocyanine blue was manufactured. Then, to 100 parts by weight of NBR with a nitrile content of 33 mol%, 80 parts by weight of a modified phenolic resin having a softening point of 80°C,
A solid obtained by dissolving in methyl ethyl ketone a heat-activated adhesive prepared by blending 50 parts by weight of a modified phenolic resin with a softening point of 120°C, 10 parts by weight of a ketone resin with a softening point of 100°C, and 10 parts by weight of chlorinated rubber. A 25% by weight solution was applied onto a release paper and dried to produce a 50 micron thick heat-activated adhesive film, which was then heat-laminated on the back side of the decorative sheet.

After applying a polyurethane primer with a solid content of 15% by weight to the decorative sheet with the heat-activated adhesive applied to the back side in this way, it was heated against a dried polyurethane bumper as shown in Figures 1 to 3. The bumper was decorated as shown in Figures 4 and 5 by adhesion using a suction device at a heating temperature of 130°C and a vacuum pressure bonding time of 1 minute.

The resin bumper decorated in this way is
The decorative sheet had a good appearance with no wrinkles or discoloration, and no air bubbles remained between the bumper surface and the decorative sheet. Next, under heating conditions of 90℃, at a temperature of 50℃ and 97%
It has been confirmed that the product maintains its normal appearance under constant temperature and humidity conditions at a relative temperature of 100,000 yen, and in environmentally accelerated deterioration tests such as ultraviolet irradiation using a weather meter.

In this embodiment, one polyurethane resin bumper was decorated, but by using a large heating and suction device, it is possible to decorate a large number of polyurethane resin bumpers at the same time.

(Effects of the Invention) As described above, in the method for manufacturing a polyurethane resin bumper according to the present invention, a molded polyurethane resin bumper with a nitrile content of 10
~40 mol% acrylonitrile-butadiene rubber
70 to 200 parts by weight of a modified phenolic resin having a softening point of 60 to 150°C per 100 parts by weight and adhesion imparting resin 2
Covering with a colored or patterned polyvinyl chloride decorative sheet coated with a heat-activated adhesive, which is a composition comprising ~100 parts by weight, the decorative sheet is attached to the polyurethane resin bumper under heating. Since this is done by applying suction and/or pressure to the surface of the bumper via the heat-activated adhesive, it is extremely easy to create a color or pattern that matches the color of the vehicle body from the viewpoint of aesthetics of the entire vehicle. can be applied to polyurethane resin bumpers. Furthermore, since there is no need to use expensive paint to form a coating film on the bumper, the number of man-hours required is extremely small, but the material and equipment costs are low.
Further, although the heat-activated adhesive can be applied to the bumper, workability is further improved if it is applied to the back surface of the decorative sheet in advance. Furthermore, since the bumper is made of polyurethane, the impact resistance is increased and the adhesion is also good, and since the decorative sheet is made of polyvinyl chloride, the adhesion is improved.

[Brief explanation of drawings]

1 to 3 are perspective views showing each step of the method of the present invention, FIG. 4 is a perspective view showing an example of a decorated resin bumper obtained by the present invention, and FIG. - is a sectional view taken along the line. 1... Polyurethane resin bumper, 2... Heating suction device, 4... Suction part, 5... Decorative sheet,
6... Polyurethane foam sheet, 7... Silicone rubber sheet for compression, 8... Heater, 9...
Heat-activated adhesive layer.

Claims (1)

[Claims] 1. On the back side of a molded polyurethane resin bumper, 100 parts by weight of acrylonitrile-butadiene rubber with a nitrile content of 10-40 mol%, 70-200 parts by weight of a modified phenolic resin having a softening point of 60-150°C, and an adhesion-imparting resin 2 Covering with a colored or patterned polyvinyl chloride decorative sheet coated with a heat-activated adhesive, which is a composition comprising ~100 parts by weight, the decorative sheet is attached to the polyurethane resin bumper under heating. suction and/or pressurization;
A method for decorating a bumper made of polyurethane resin, the method comprising adhering the bumper to the surface of the bumper via the heat-activated adhesive.