JPS6117679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a hot-stamped polyolefin molded article that has good hot-stamping properties, that is, the hot-stamped foil adheres well to the molded article. As is well known, polyolefins are widely used due to their excellent physical properties and relatively low cost, but because they do not have polar groups in their molecules, the adhesion of hot stamping foils is poor.
It was significantly worse than ABS resin, polystyrene, etc., and had the disadvantage of not being able to provide a practical level of adhesion.

Conventional methods for improving the adhesive properties of polyolefin include surface treatment methods such as flame treatment, corona treatment, and chromic acid immersion treatment on the surface of polyolefin molded products, but these methods require extra steps. Therefore, not only is it expensive, but
Flame treatment has various disadvantages in practical use, such as difficulty in uniform treatment depending on the shape of the molded product, and deterioration of surface appearance.

The inventors of the present invention have conducted extensive research to overcome these drawbacks, and as a result, have arrived at the present invention.

The present invention is a method for producing a hot-stamped polyolefin molded article, which comprises hot-stamping a polyolefin resin molded article containing 0.1 to 10% by weight of a vinyl monomer containing a glycidyl group as a unit component.

The polyolefin resin herein refers to a homopolymer of α-olefin such as ethylene or propylene or a copolymer thereof, a copolymer of α-olefin and other monomers, or a mixture of these polymers. . Furthermore, it also includes blends with appropriate amounts of fillers such as talc and calcium carbonate, and elastomers.

Next, in order to incorporate a vinyl monomer having a glycidyl group as a unit component into a polyolefin resin, it can be easily obtained by blending a copolymer of ethylene and a vinyl monomer containing a glycidyl group with the polyolefin resin. Examples of the vinyl monomer containing a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and glycidyl ethacrylate.

Alternatively, these monomers may be directly grafted onto the polyolefin resin.

Practical effects cannot be expected if the amount of the vinyl monomer unit component having a glycidyl group in the resin used for molding is too small, so it should be 0.1 to 10% by weight.
Preferably it is 0.3 to 7% by weight. If the amount is too large, it is not desirable in terms of adhesion, but it not only increases the price but also impairs the properties of the polyolefin resin.

Using the molding resin thus obtained, a molded article is obtained by a conventional method such as injection molding, extrusion molding, blow molding, etc., which is suitable for the desired molded article. Next, the molded article is hot-stamped as desired, and this can also be done in a conventional manner.

That is, on a base film such as polyester,
A hot stamp foil is used in which a release layer is sequentially coated, a decorative layer (a pigment coating layer, a vapor deposition layer, a printing layer such as wood grain, etc.) is provided on top of the release layer, and an adhesive layer is further coated.

This foil is placed on top of the molded product so that the adhesive layer is in contact with the molded product, and a heated mold with letters, figures, etc. engraved in a convex manner is pressed onto the base film, and the letters and figures are transferred. If you want to transfer only to a small convex part of a molded product, you can press it with a flat heated rubber plate, and if you want to transfer it to the entire relatively wide surface, you can press it with a heated rubber roll instead of the rubber plate.

After heating and pressing, the base film is pulled and is easily peeled off from the release layer, and the decorative layer and protective layer are transferred onto the molded product by the adhesive layer, and the desired hot stamping is completed. A molded product is obtained.

In the present invention, since the above resin is used as the molding resin, the adhesiveness of the foil is good, and not only the initial adhesion but also the water resistance of the hot stamp is improved, resulting in a durable hot-stamped molded product. .

This will be explained in detail below using examples.

Example 1 Homopolypropylene 97 with melt index 8
Weight and copolymer of glycidyl methacrylate and ethylene, glycidyl methacrylate is 20
Mixing 3 parts by weight of a copolymer consisting of 80% by weight of ethylene and having a melt index of 80,
A molding resin was obtained through an extruder. Now the thickness is 2
mm plate is molded by injection molding, and without any surface treatment, letters with a stroke of 5 mm width are engraved into convex shapes using Kuruziyapan's gold-deposited hot stamp foil. The temperature of the mold was set to 170°C, and letters were hot stamped onto the injection plate. On top of this is a Nichiban cloth
The adhesion of the foil to the molded product was examined by applying 24 mm cellophane tape to the foil with a fingertip and peeling it off rapidly.

The foil hot-stamped onto the molded product is not picked up by the Sellotape at all, and the percentage of foil remaining on the molded product is low.
It was 100%.

Comparative Example 1 In Example 1, a plate was molded only from homopolypropylene with a melt index of 8, hot stamped in the same manner, and a sellotape peel test was performed. The remaining rate was 50%.

Example 2 A copolymer of ethylene and glycidyl methacrylate, consisting of 80% by weight of polypropylene copolymerized with ethylene and 20% by weight of talc, and 90 parts by weight of polypropylene resin with a melt index of 8, and 85% by weight of ethylene and glycidyl methacrylate. methacrylate 15
10 parts by weight of a copolymer with a melt index of 50 were mixed and passed through an extruder to obtain a molding resin. A plate with a thickness of 2 mm was then molded by injection molding.

Hot stamping was performed on the molded product without any surface treatment. In this case, a chrome-deposited foil made by Kurzzi Japan was used as the hot stamp foil, and a 90 x 150 mm
A hot stamp was applied to the entire surface. Regarding this, the cellophane tape peeling test described above was performed, and the hot-stamped molded product was immersed in warm water at 40℃ for 70 minutes.
After soaking for a period of time, a similar peel test was conducted. In both peeling tests, the residual rate was 100%, the cellophane tape did not peel off at all, and the foil adhered extremely well to the molded product.

Comparative Example 2 In Example 2, a plate was molded using only polypropylene resin, hot stamped in the same manner, and a sellotape peel test was conducted. The residual rate was 65% before immersion in hot water and 10% after immersion.

Example 3 90 parts by weight of high-density polyethylene with a melt index of 7.0 and a density of 0.955 and 10 parts by weight of the ethylene and glycidyl methacrylate copolymer used in Example 1 were blended and plate molded using an injection molding machine. Hot stamping was performed in the same manner and a peel test was performed, but the adhesiveness was good and the retention rate was 100%.

Comparative Example 3 In Example 4, a molded article was made only from high-density polyethylene, hot-stamped in the same manner, and a peel test was performed, and the residual rate was 20%.

Claims (1)

[Claims] 1. A method for producing a hot-stamped polyolefin molded article, which comprises hot-stamping a polyolefin resin molded article containing 0.1 to 10% by weight of a vinyl monomer having a glycidyl group as a unit component.