JP2938941B2 - Hard coat sheet for molding and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hard coat sheet for molding, and more particularly to a hard coat sheet having a surface layer excellent in high hardness, scratch resistance, abrasion resistance, stain resistance and the like. The present invention also relates to a hard coat sheet for molding that can be molded into various molded articles.

(Prior art) Conventionally, acrylic resins, polystyrene resins, polycarbonate resins, and other synthetic resins have various advantages such as good moldability, excellent transparency, light weight, and low cost. It is widely used as molded products such as various industrial materials, building materials, decorative materials, optical materials, light electric materials, cosmetic materials, household materials and the like.

On the other hand, although such a resin molded article has the above-mentioned various advantages, its surface hardness is lower than that of glass, metal, etc., so that the surface is easily scratched, the transparency is reduced, and the contamination is reduced. There is a problem that the property is increased.

As a method of solving such a problem, there is a method of forming a hard surface layer by spray-coating a hard resin paint on a surface after molding into a desired shape, thereby forming a hard surface layer. There are various problems such as a problem of volatilization, a molded article is limited to those having excellent heat resistance and solvent resistance, dust easily adheres to a surface layer during coating, and a high cost.

As a method for solving such a problem, there is a method in which a hard surface layer is previously formed on the surface of a resin sheet for molding, and this is subjected to molding. In this case, since the surface layer is hard, There is a problem that the surface layer is cracked or peeled off in a molded portion having a large curvature.

If the surface layer is formed from a soft resin having good moldability, such a problem does not occur, but a molded article having satisfactory surface properties cannot be obtained.

Accordingly, the object of the present invention is to solve the various problems of the prior art as described above, and even if it is formed into a curved surface or a corner portion as well as a flat surface, deterioration in appearance and scratch resistance at those portions due to cracks and the like. It is an object of the present invention to provide an excellent hard coat sheet for molding without a decrease in physical properties such as.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention comprises, on at least one surface of the substrate sheet having moldability, a layer made of a soft ionizing radiation-curable resin and a hard coat layer made of a hard ionizing radiation-curable resin in the order of this description. A molding hard coat sheet characterized by being laminated, and a method for producing the same.

(Function) In the hard coat sheet for molding of the present invention, the soft layer is on the inside and the hard hard coat layer is on the surface. Therefore, when this curved hard coat sheet is formed to form a curved surface or a corner portion, cracks may be generated in the hard hard coat layer on the surface, but the cracks generated due to the thin hard coat layer on the surface may be visually recognized. There was no problem with the appearance. Further, since the crack portion is in close contact with the soft layer thereunder, it does not peel off.

Preferred Embodiment Next, the present invention will be described in more detail with reference to the accompanying drawings, which show a preferred embodiment schematically.

In the hard coat sheet for molding of the present invention, as shown in FIG. 1, layers 2 and 3 are formed on at least one surface of a base sheet 1, and the layers 2 and 3 are made of a hard ionizing radiation-curable resin. It comprises a hard coat layer 2 and a layer 3 made of a soft ionizing radiation curable resin.

Furthermore, a primer layer or a decoration layer can be provided between the base sheet 1 and the layer 3 as needed. The decorative layer may be any pattern such as a pattern of natural products such as wood grain and stone grain, a character, a symbol, an abstract pattern, and a solid pattern on the entire surface, and may be provided on the entire surface or partially.

The substrate sheet 1 used in the hard coat sheet for molding of the present invention may be any conventionally known substrate sheet as long as it has moldability. For example, polyethylene terephthalate, polyethylene terephthalate / isophthalate copolymer It is a sheet of plastic such as coalesce, polyester such as polybutylene terephthalate, polyethylene, polypropylene, polyolefin such as polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyamide, etc., having a thickness of several tens μm to several tens cm. Is fine.

The layers 2 and 3 provided on the base sheet 1 as described above are formed from an ionizing radiation-curable paint. Particularly preferred ionizing radiation curable paints are electron beam curable paints and UV curable paints.

Electron beam-curable paints and ultraviolet-curable paints are similar in composition except that the latter contains a photopolymerization initiator or a sensitizer, and generally have a structure as a film-forming component. Polymer, oligomer, monomer, etc. having a radical polymerizable double bond or epoxy group in the main component,
It contains a non-reactive polymer, an organic solvent, a wax, and other additives as necessary.

Particularly preferred for the purpose of the present invention, those in which the film-forming component has an acrylate-based functional group, for example, a polyester resin having a relatively low molecular weight, a polyether resin, an acrylic resin, an epoxy resin, a urethane resin, an alkyd resin, Spiro acetal resin, polybutadiene resin, polythiol polyene resin, oligomer or prepolymer such as (meth) acrylate of polyfunctional compound such as polyhydric alcohol and ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, as reactive diluent Monofunctional monomers such as methylstyrene and N-vinylpyrrolidone and polyfunctional monomers, for example, trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate , Diethylene glycol (meth) acrylate, pentaerythritol tri (meth)
Acrylate, dipentaerythritol hexa (meth)
It contains relatively large amounts of acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, and the like.

By using such a polyfunctional (meth) acrylate-based ionizing radiation-curable paint, a hard coat layer excellent in surface hardness, transparency, abrasion resistance, abrasion resistance and the like can be formed.

Further, when such a hard coat layer is required to have high flexibility and shrink resistance, an appropriate amount of a thermoplastic resin such as a non-reactive acrylic resin or various waxes is contained in the above-mentioned curable coating. Can be used to meet those requirements.

Further, in order to make the above-mentioned curable paint into an ultraviolet-curable paint, acetophenones, as photopolymerization initiators therein,
Benzophenone, Michler benzoyl benzoate, α
-Amyloxime esters, tetramethylthiuram monosulfide, thioxanthones, and n-butylamine, triethylamine, tri-n-butylphosphine, and the like as photosensitizers can be mixed and used.

Various types of ionizing radiation curable paints such as the above-mentioned electron beam or ultraviolet curable paints are known, and all of them are easily available from the market and can be used in the present invention.

The feature of the present invention resides in that the layers 2 and 3 are separately formed into a hard hard coat layer 2 and a soft layer 3.

The hard hard coat layer 2 is formed by using a relatively large amount of a polyfunctional monomer as a component of the ionizing radiation-curable resin. Preferred hardness is AS
When the thickness is 10 μm on the sheet, the pencil hardness is 2H or more, and the elongation is preferably in the range of 1 to 30%. 2H pencil hardness
If it is less than this, the function as a hard coat layer cannot be obtained.

The thickness of the hard hard coat layer 2 is preferably about 0.1 to 2 μm, and if it is too thin, uniform application is difficult and the hardness is insufficient, and the surface protection effect of the molded article becomes insufficient. On the other hand, if the thickness is too large, whitening is conspicuous due to the occurrence of cracks in the curved surfaces such as corners of various molded articles, which is not preferable in appearance.

On the other hand, the soft layer 3 reduces the ratio of the polyfunctional monomer as a component of the ionizing radiation-curable resin,
By mixing a non-reactive resin with excellent flexibility,
It can be formed by adjusting its hardness.

Preferred hardness is 10 μm thickness on AS sheet
The pencil hardness is about 3B to H, and the elongation is preferably 25% or more. If it is too hard, the soft layer 3 itself will be whitened or cracked during molding, and the object of the present invention cannot be achieved. On the other hand, if it is too soft, the function as a surface layer cannot be obtained.

The thickness of the soft layer 3 is preferably about 1 to 50 μm. If the thickness is too thin, the surface protection effect of the formed article becomes insufficient. On the other hand, if the thickness is too thick, the deformability of the layer becomes harder. It is transmitted to the layer 2 and lowers the hardness of the hard layer 2.

The total thickness of the above hard and soft layers is 1 to 50 μm
The degree is preferred.

Conventional techniques can also be used as the curing method for the layers 2 and 3 described above. For example, in the case of electron beam curing, Cockloft-Walton type, Bandegraf type, Resonant transformer type, Insulating core transformer type, Linear type, Dynamitron type , 50 to 1,000 KeV, preferably 10 to 10 emitted from various electron beam accelerators such as high-frequency type
An electron beam or the like having an energy of 0 to 300 KeV is used,
In the case of ultraviolet curing, ultraviolet rays emitted from a light source such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp are used.

Irradiation with ionizing radiation may be performed each time each layer is formed, or may be performed after both layers are formed.

The curable paint as described above can be prepared by any coating method such as a blade coating method, a gravure coating method, a rod coating method, a knife coating method, a reverse roll coating method, a spray coating method, an offset gravure coating method, and a moss coating method. It is applied on the above-mentioned base material sheet, and in particular, a gravure coating method, a gravure reverse coating method, a reverse roll coating method, an offset gravure coating method, etc., which are excellent in the accuracy of the coating thickness, the smoothness of the applied surface, and the like are preferable. .

The hard coat sheet for molding of the present invention obtained as described above can be used for any conventionally known molding methods such as press molding and vacuum molding.

(Effects) According to the present invention as described above, the hard coat sheet for molding of the present invention has a soft layer on the inside and a hard hard coat layer on the surface. When such a hard coat sheet for forming is formed as shown in FIG. 2 to form a curved surface or a corner portion, fine cracks may be generated in the hard hard coat layer on the surface, but the hard coat layer on the surface is hardly formed. Since it is thin, the cracks generated are not visible to the naked eye and there is no problem in appearance. Further, since the crack portion is in close contact with the soft layer thereunder, it does not peel off.

(Examples) Next, the present invention will be described more specifically with reference to examples and comparative examples.

Example 1 A surface of a polycarbonate sheet (300 μm thick) manufactured by Mitsubishi Rayon Co., Ltd. was coated with ionizing radiation-curable resin HC-C.
(Moroboshi Ink) is applied to a thickness of 10 μm when dried,
After drying at 1 ° C. for 1 minute, an ionizing radiation-curable resin HC-A (manufactured by Morohoshi Ink) was further applied on the surface to a thickness of 0.5 μm when dried, and dried at 60 ° C. for 1 minute.

Using a scanning type electron beam irradiator for the above coating layer, acceleration voltage 175KV, beam current 36mA, irradiation dose 10Mrad
Then, each layer was cured by irradiating with an electron beam to obtain a hard coat sheet for molding of the present invention.

Comparative Example 1 A molding hard coat sheet of a comparative example was obtained in the same manner as in Example 1 except that the hard coat layer was formed to have a thickness of 10 μm using only a hard ionizing radiation-curable resin (HC-A).

Comparative Example 2 A molding hard coat sheet of a comparative example was obtained in the same manner as in Example 1 except that the hard coat layer was formed of a soft ionizing radiation curable resin (HC-C) to a thickness of 10 μm.

When the hard coat sheets for molding of the above Examples and Comparative Examples were vacuum molded, the results of the obtained molded articles were as follows.
It was as shown in the table.

1. Formability: Forming process of 10R was performed and evaluated visually.

 ：: Cracks and whitening are not conspicuous. No detachment of the membrane.

 ×: Cracks and whitening are conspicuous. Some films have fallen off.

2. Pencil hardness: evaluated with a load of 500 g.

3. Scratch resistance: Use # 0000 steel wool, lightly 100
It was rubbed and evaluated.

 ：: Whitening is not conspicuous.

 X: Whitening is conspicuous.

[Brief description of the drawings]

FIG. 1 schematically shows a cross section of a hard coat sheet for molding of the present invention, and FIG. 2 is a view for explaining a molded state. 1: Base sheet 2: Hard hard coat layer 3: Soft layer

Claims (4)

(57) [Claims] 1. A layer comprising a soft ionizing radiation-curable resin and a hard coat layer comprising a hard ionizing radiation-curable resin are laminated on at least one surface of a moldable base material sheet in the stated order. A hard coat sheet for molding, characterized by being formed by: 2. The hard hard coat layer has a thickness of 0.1 to 2 μm.
The hard coat sheet for molding according to claim 1, wherein the thickness of the soft layer is 1 to 50 µm. 3. The hard coat sheet for molding according to claim 1, wherein a decorative layer is provided between the base sheet and the soft layer. 4. A layer made of a soft ionizing radiation-curable resin is provided on at least one surface of a moldable base material sheet.
A hard coat layer made of a hard ionizing radiation-curable resin is formed to a thickness of 0.1 to 2 μm on the surface of the layer, and ionizing radiation is applied every time each of the above layers is formed or after both layers are formed. A method for producing a hard coat sheet for molding, characterized by irradiating.