JPH0493245A - Forming hard coating sheet and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the deterioration of external appearance due to crack and the like and the lowering of physical properties such as resistance to scuffing and the like from developing even at forming in curved surface of corner by a method wherein layer made of non-rigid ionizing radiation curing resin and hard coating layer made of rigid ionizing radiation curing resin are laminated in the order named onto at least one side of formable base material sheet. CONSTITUTION:The sheet concerned consists of hard coating layer 2 made of rigid ionizing radiation curing resin and layer 3 made of non-rigid ionizing radiation curing resin laminated onto at least one side of base material sheet 1. As the base material 1, plastic sheet made of polyester such as polyethylene terephthalate, polybutylene terephthalate or the like having preferable thickness of from several ten mum to several. ten cm. As the ionizing radiation coating paint. of which the layers 2 and 3 are made, electron radiation curing paint or ultraviolet curing paint is preferable. The electron radiation curing paint and the ultraviolet curing paint have the same components as each other excluding that the latter contains photopolymerization initiator and sensitizer and mainly contain polymer, oligomer, monomer, or the like having radical polymerizable double bond or epoxy group in their structure as film forming component as general.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a hard coat sheet for molding, and more specifically, a sheet having a surface layer with high hardness, excellent scratch resistance, abrasion resistance, stain resistance, etc. The present invention also relates to a moldable hard coat sheet that can be molded into various molded products.

(Prior art) Acrylic resins, polystyrene resins, polycarbonate resins, and other synthetic resins have traditionally had various advantages such as good moldability, excellent transparency, light weight, and low cost. It is widely used as molded products for various industrial materials, building materials, decorative materials, optical materials, weak electrical materials, cosmetic materials, household materials, etc.

On the other hand, although such resin molded products have various advantages as mentioned above, their surface hardness is lower than that of glass, metal, etc., so the surface is easily scratched, transparency is reduced, and contamination may occur. There are problems such as increased sexual activity.

One way to solve these problems is to form a hard resin paint onto the surface after molding it into the desired shape and then harden it to form a hard surface layer. There are various problems such as volatilization, molded products are limited to those with excellent heat resistance and solvent resistance, dirt and the like tend to adhere to the surface layer during painting, and high cost.

One way to solve this problem is to form a hard surface layer in advance on the surface of a resin sheet for molding, and then use this for molding.In this case, since the surface layer is hard, Molded parts with large curvatures have the problem of cracking or peeling of the surface layer.

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

Therefore, an object of the present invention is to solve the various problems of the prior art as described above, and to prevent deterioration of appearance due to cracks and scratch resistance in those parts even when molded on not only flat surfaces but also curved surfaces and corner parts. It is an object of the present invention to provide an excellent hard coat sheet for molding without deterioration of physical properties such as.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a layer made of a soft ionizing radiation-curable resin and a hard coat layer made of a hard ionizing radiation-curable resin on at least one surface of a base sheet having moldability in the order described above. A hard coat sheet for molding characterized by being formed by laminating layers, and a method for manufacturing the same.

(Function) The hard coat sheet for molding of the present invention has a soft layer inside and a hard hard coat layer on the surface. Therefore, when this hard coat sheet for molding is molded to form a curved surface or a part of a corner, cracks may occur in the hard hard coat layer on the surface, but since the hard coat layer on the surface is thin, the cracks that occur are visible to the naked eye. There is no problem with the appearance. Furthermore, since the cracked portion is stuck to the soft layer below, it will not peel off.

(Preferred Embodiments) The present invention will now be described in more detail with reference to the accompanying drawings which schematically show preferred embodiments.

The hard coat sheet for molding of the present invention is as shown in the first figure (
, layers 2 and 3 are formed on at least one surface of the base sheet 1, and the layers 2 and 3 are a hard coat layer 2 made of a hard ionizing radiation curable resin and a layer made of a soft ionizing radiation curable resin. It is composed of 3.

Furthermore, a brimer layer or a decorative layer can be provided between the base sheet 1 and the layer 3 if necessary.

As a decorative layer, natural patterns such as wood grain and stone grain, letters,
It may be any pattern such as a symbol, an abstract pattern, or an all-over solid pattern, and may be provided on the entire surface or partially.

The base sheet 1 used in the hard coat sheet for molding of the present invention may be any conventionally known base sheet as long as it has moldability (for example, polyethylene terephthalate, polyethylene terephthalate/isophthalate, etc.). These are sheets of polymers, polyesters such as bobblylene terephthalate, polyolefins such as bobblylene, polypropylene, polymethylpentene, etc., plastics such as polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyamide, etc., and have a thickness of several tens of micrometers to several tens of centimeters. Anything is fine.

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 ultraviolet-curable paints.

Electron beam-curing paints and UV-curing paints are similar in composition, except that the latter contains photopolymerization initiators and sensitizers; The main component is a polymer, oligomer, 7mer, etc. that has a radically polymerizable double bond or epoxy group in its structure, and contains other non-reactive polymers, organic solvents, wax, and other additives as necessary. It is something.

Particularly preferred for the purpose of the present invention are those in which the film-forming component has an acrylate functional group, such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, Oligomers or prepolymers such as (meth)acrylates of polyfunctional compounds such as spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols, and reactive diluents such as ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene,
Monofunctional monomers such as methylstyrene and N-vinylpyrrolidone as well as polyfunctional monomers such as trimethylolpropane tri(meth)acrylate, hexanediol(meth)acrylate, tribrobylene glycol di(
Comparison of meth)acrylate, diethylene glycol (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol(meth)acrylate, etc. It contains a large amount.

By using such a polyfunctional (meth)acrylate-based ionizing radiation-curable paint, surface hardness, transparency,
A hard coat layer with excellent abrasion resistance, scratch resistance, etc. can be formed.

Furthermore, if such a hard coat layer is required to have high flexibility or shrinkage resistance, an appropriate amount of thermoplastic resin such as non-reactive acrylic resin or various waxes may be added to the above-mentioned curable coating. These demands can be met by adding .

In addition, in order to convert the above-mentioned curable paint into an ultraviolet curable paint,
These include acetophenones, benzophenone, Michler benzoyl benzoate, α-amyloxime ester, tetramethylthiuram monosulfide, thioxanthone as photopolymerization initiators, and n-butylamine, triethylamine, tri-n-butylphosphine as photosensitizers. etc. can be used in combination.

Various grades of ionizing radiation curable coatings such as electron beam or ultraviolet ray curable coatings as described above are known, and any of them can be easily purchased from the market and used in the present invention.

A feature of the present invention is that the layers 2 and 3 are formed separately into a 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 above-mentioned ionizing radiation curable resin. The preferred hardness is AS
When formed on a sheet with a thickness of 10 μm, the pencil hardness is 2H or more, and the elongation is preferably in the range of 1 to 30%. If the pencil height is less than 2H, 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; if it is too thin, it will be difficult to apply uniformly and the hardness will be insufficient, and the surface protection effect of the article after molding will be insufficient. On the other hand, if it is too thick, cracks will occur on the curved surfaces of the various molded articles, such as some corners, and whitening will be noticeable, which is unfavorable in terms of appearance.

On the other hand, the hardness of the soft layer 3 can be adjusted by reducing the proportion of the polyfunctional monomer as a component of the above-mentioned ionizing radiation curable resin or by mixing a non-reactive resin with excellent flexibility. It can be formed by

The preferred hardness is a pencil hardness of about 3B-H when applied to an AS sheet with a thickness of 10 μm, and the elongation is preferably 25% or more. If it is too hard, the soft layer 3 itself will whiten or crack during molding, making it impossible to achieve the object of the present invention. Moreover, if it is too soft, it cannot function as a surface layer.

The thickness of the soft layer 3 is preferably about 1 to 50 Im. If it is too thin, the surface protection effect of the molded article will be insufficient. On the other hand, if it is too thick, the deformability of this layer will be reduced by the hard layer above it. This is transmitted to the layer 2 and reduces the hardness of the hard layer 2.

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

Conventional techniques can be used as is for curing the layers 2 and 3. For example, in the case of electron beam curing, Cockroft-Walton type, bumpgraph type, resonant transformer type, insulated core transformer type, linear type, Dynamidron type, etc. Electron beams with an energy of 50 to 1,000 KeV, preferably 100 to 300 KeV, emitted from various types of electron beam accelerators such as type and high frequency type are used. , ultraviolet rays emitted from light sources such as low-pressure mercury lamps, carbon arcs, xenon arcs, metal halide lamps, etc. are used.

Irradiation with ionizing radiation may be performed each time the above layers are formed, or after both shoulders are formed.

The above-mentioned curable paints include, for example, 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, a moss coating method, etc.
Although it can be coated on the above base sheet by any coating method, gravure coating method, gravure reverse coating method, reverse roll coating method, offset gravure coating method is particularly excellent in coating thickness accuracy, coating surface smoothness, etc. etc. are suitable.

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

(Effects) According to the present invention as described above, the hard coat sheet for molding of the present invention has a soft layer inside and a hard hard coat layer on the surface. When such a hard coat sheet for molding is molded to form a curved surface or a part of a corner as shown in the second figure, fine cracks may occur in the hard hard coat layer on the surface, but the hard coat layer on the surface Since the material is thin, cracks that occur cannot be seen with the naked eye and there is no problem with appearance.

Furthermore, since the cracked portion is in close contact with the soft layer below, it will not peel off.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples.

Example 1 Polycarbonate sheet manufactured by Mitsubishi Rayon Co., Ltd. (thickness 30
Ionizing radiation curing resin HC-C (manufactured by Moroboshi Ink) was applied to the surface of
After drying at 60° C. for 1 minute, an ionizing radiation curable resin HC-A (manufactured by Moroboshi Ink) was coated 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 irradiation machine for the above coating layer,
Acceleration voltage 175KV, beam current 36mA, irradiation dose 1
Each layer was cured by irradiating with an electron beam at 0 Mrad to obtain a hard coat sheet for molding of the present invention.

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

Comparative Example 2 A hard coat sheet for molding 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 formed, the results of the molded products obtained were as shown in Table 1 below.

1. Moldability: IOR was molded and evaluated visually.

O: Cracks and whitening are not noticeable. membrane No falling off.

×: Cracks and whitening are noticeable. Some pus There is some falling off.

2. Pencil hardness; evaluated under a load of 500 g.

3. Scratch resistance: evaluated by rubbing lightly <100 times using 5oooo steel wool.

○: Whitening is not noticeable.

X: Whitening is noticeable.

[Brief explanation of drawings]

FIG. 1 schematically shows a cross section of the hard coat sheet for molding of the present invention, and FIG. 2 is a diagram illustrating the molded state. 1: Base sheet 2: Rigid hard coat layer 3: Soft layer Patent applicant: Dai Nippon Printing Co., Ltd. Figure 1 Figure 2

Claims (4)

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