JPH0474194B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a treatment method for increasing the adhesion of a substrate surface, particularly a highly hard substrate surface, to adhesives, printing inks, etc., and a hard surface with excellent adhesion obtained thereby. The present invention relates to a sheet and a transfer foil having the following properties. Prior Art It is generally difficult to stably adhere a resin to the surface of a highly hard base material. Therefore, in order to apply printing processing to enhance the design of characters, patterns, etc. and adhesive processing to enhance functionality to the surface of hard substrates, pretreatments such as chemical reaction treatment, oxidation treatment, It has been considered necessary to perform primer treatment and the like. By the way, the following two points are particularly important factors that affect the printability and adhesion to the surfaces of various base materials. One is the wettability of the substrate surface, which is related to surface tension, and the other is the adhesion to the substrate surface, which is related to physical bonding and chemical bonding. Therefore, the above pretreatment is performed to improve these two factors, and corona discharge treatment, which is an oxidation treatment, is the most excellent method, especially for film-like substrates. It has been widely implemented. This roughens the surface of the substrate by corona discharge and introduces polar groups to increase surface tension and improve wettability, making it easier to wet with printing ink and adhesives. However, this method cannot be expected to significantly improve adhesion. Another method is so-called priming. For example, it improves the adhesion of polyethylene terephthalate film substrates by applying a thin film of urethane-based cured resin with isocyanate groups to the surface of the substrate as a primer layer. It enhances sexuality. However, the base materials that can be used in primer treatment with resin are limited. For example, the surface of the base material is highly hard and has been given hard coat properties by hard coat silicone hardening resin, hard coat melamine hardening resin, hard coat ultraviolet hardening resin, hard coat electron beam hardening resin, etc. In the case where the resin used for the primer treatment has excellent physical properties such as solvent resistance, heat resistance, and high hardness, the resin itself does not have adhesiveness to the surface of the base material. Additionally, primer treatment has the following problems. For example, when imparting hard coat properties to the surface of a base material, a hard coat resin mixed with a thermoplastic resin or the like to reduce the hard coat properties is applied to the base material to reduce the energy on the surface of the hard coat layer. This may improve the adhesion with the primer layer formed on it, but this not only reduces various physical properties such as hard coat properties, but also increases the adhesion of the surface with solvent resistance and high hardness. This results in the formation of a primer layer with no properties, resulting in a problem in that the characteristics that provide hard coat properties are largely lost. From the above, it is thought that there is a limit to the improvement of printability and adhesion by mere pretreatment of the substrate, and various processing methods have been investigated. For example, a method of drying a hard coat silicone resin to a tack-free state, forming a primer layer thereon, and then curing the silicone resin by heating etc. to impart adhesive properties, or releasing a release sheet. The hard-coat UV-curable resin applied to the mold surface is dried to a tack-free state, and layers of printing ink, adhesive, etc. are sequentially formed to create a transfer foil. After transferring it to the molded product, UV rays are irradiated.
There are methods of hardening. These methods are usually referred to as after-cure type methods. However, these methods also have the following problems. For example, in the former case, the hard coat silicone cured resin layer may be dissolved by the solvent contained in the primer layer during application of the primer layer, causing whitening, unevenness, etc. The resins in the layer mix, causing problems such as not being able to obtain high hardness.
It is difficult to obtain a practical product. Furthermore, the latter requires secondary processing of irradiation with ultraviolet rays after transfer, and is not only expensive, but also has problems such as poor transfer heat resistance, uneven flow during transfer, and non-dimensional stability. Problems to be Solved by the Invention The present invention aims to stably improve the adhesion of the surfaces of substrates with high hardness, such as hard coat resins, ceramics, etc., to printing inks and adhesives. The objective is to provide a practical treatment method that can be used. Furthermore, the present invention also provides a sheet having a hard surface with excellent adhesion by improving the adhesion of the hard coat resin, and a transfer foil that effectively uses the hard coat resin. The challenge is also to make it possible. Means for Solving the Problems In the present invention, the above problems were solved by forming a transparent thin film made of an inorganic substance on the surface of a hard base material. That is, the method of the present invention complies with JIS K 5400.
6.14. By forming a transparent thin film made of an inorganic substance on the surface of a hard base material whose hardness as determined by a pencil scratch test (hereinafter referred to as pencil hardness) is H or higher, adhesives or This allows printing ink to adhere stably. The transparent thin film made of inorganic material has a pencil hardness of H~
On the surface of a base material such as 3H, it may be formed as a continuous thin film or as a discontinuous thin film; It is preferable to form a discontinuous thin film on the surface of the material. This is because an inorganic substance such as a metal or a metal compound is formed into a discontinuous thin film in the form of atomic particles or an island structure (so-called nucleation), which increases the energy on the surface of the base material. This is thought to be due to the remarkable improvement in both wettability and adhesion. As a method for forming a transparent thin film made of an inorganic substance on the surface of a hard substrate, any of various vapor deposition methods such as a vacuum vapor deposition method, an ion plating method, and a sputtering method can be effectively used. Ion plating method or sputtering method is preferable to particularly obtain the effect of increasing adhesiveness. but,
In terms of mass production, cost, etc., the vacuum deposition method is the easiest to use. Next, as an inorganic substance that forms a transparent thin film,
It is not particularly limited as long as it can be so-called nucleated. Such substances include, for example,
Ag, Al, Au, Cd, Co, Cr, Cu, Fe, Li, Ms,
Metals such as Mn, Ni, Pb, Pt, Sn, Ti, Zn, In,
Examples include metalloids such as Ge, Si, Sb, Te, Se, and As, and oxides, sulfides, and halides thereof. Note that examples of the latter include SiO, PbO,
Examples include SnO ₂ , ZnS, CdS, MgF ₂ and LiF. Among these, inorganic substances that are particularly effective are those that have a high evaporation temperature, a coefficient of thermal expansion that is close to the substrate surface, or that have low shrinkage stress during film formation, and Cr, Mn, etc., which have sublimation deposition properties, are the most effective. It is a preferred substance. The transparent thin film made of an inorganic substance formed on the surface of a hard substrate may have a visible light transmittance of 50% or more, and its thickness is not particularly limited, but it is generally about 10 to 500 Å, particularly non-woven. It is preferable to use a film thickness of about 50 to 200 Å, which results in a continuous thin film. In the present invention, the adhesion strength of conventional printing ink etc. is 0/100 in the cross-cut Sellotape test, but the hardness of the pencil hardness (JIS K 5400 6.14. Hardness by pencil scratch test) is 2H or more. Also,
It can provide a practical adhesive strength of 100/100 in the grid Cellotape test. For example, if we simply express the adhesive force (strength when peeling off) using the formula (1), we can obtain the following: Adhesive force = Bonding force - Stress between two layers...Equation (1) Bonding force: Physical adsorption between substances, chemical bonding,
Entanglement of molecules, etc. Stress between two layers: Internal stress accumulated between two layers. The present invention increases bonding strength by forming a transparent thin film made of an inorganic substance, and in some cases, further forms the transparent thin film in a discontinuous state to prevent stress between the two layers from increasing. Therefore, it can be said that a measure was taken to increase the adhesive strength. In general, the film formation process in vapor-deposited thin film formation is observed to be as follows: atomic grains/molecular grains → minute aggregates → island-like structure amalgamation → whole-surface film formation, but stress increases here because of the island-like structure. The stage from the fused body to the entire surface film formation is remarkable, and before this stage the stress is extremely small. Furthermore, before this point, the difference in expansion rate appears to have little influence. Normally, transparent thin films (discontinuous thin films) made of inorganic substances with an island-like structure or less, which cannot be formed on the entire surface, have a non-metallic luster or a semi-metallic luster and have non-barrier properties, so they cannot be used. It was said that there was not much of a way to go. The present invention utilizes a transparent thin film in a discontinuous state ranging from atomic grains to island-like structural amalgams on the surface of a hard base material with a pencil hardness of 2H or more, and furthermore, since inorganic substances can be used, it is heat resistant. It is possible to provide adhesive properties with thermoplastic polyester resin, vinyl chloride resin, vinyl acetate resin, etc. without reducing the performance of the base material surface, such as hardness, high hardness, solvent resistance, and transparency. It is. Further, in the present invention, since extremely excellent adhesiveness can be imparted to the surface of a hard base material, it is also possible to provide a sheet having a hard surface with excellent adhesiveness that allows stable printing on the surface. This sheet is a sheet that has a hard surface with a pencil hardness of H or higher (for example, a sheet obtained by forming a hard coat layer on the surface of a base material such as a transparent film). A transparent thin film made of an inorganic substance is formed on the hard surface of the sheet. This is what happens. Since the surface of this sheet has excellent printability and adhesion, a conductive film can be provided on the back surface and it can be used very effectively for manufacturing calculators, word processors, or touch panels for the operation parts of electrical appliances. This sheet also has a surface hardness of 2H pencil hardness.
In the above case, it is preferable that the transparent thin film made of an inorganic substance be formed in a discontinuous state. Furthermore, in the present invention, a transparent resin layer having a hardness of pencil hardness H or higher is provided on the release surface of the release sheet,
By forming a transparent thin film made of an inorganic substance thereon, and sequentially forming a printed pattern and an adhesive layer on this transparent thin film, it is possible to obtain a transfer foil that is of great industrial value. . When this transfer foil is used, a highly hard transparent resin layer that is chemically and physically stable and allows printed patterns to be seen through can be transferred onto the surfaces of various transfer objects. In particular, by using a transparent resin layer with a pencil hardness of 2H or more and forming a transparent thin film made of an inorganic substance in a discontinuous state on top of the transparent resin layer, it is possible to easily obtain a transparent resin layer that cannot be easily obtained using conventional transfer methods. It becomes possible to transfer a highly hard transparent resin layer with very good surface characteristics and a stable printed pattern. Note that the transfer foil of the present invention does not necessarily have a printed pattern, and since an adhesive layer may also be appropriately formed on the transfer target, it does not necessarily have this. Examples Next, Examples and Comparative Examples of the present invention will be shown, but the present invention is not limited to the Examples. Note that the physical property test results in Examples and Comparative Examples were measured by the following method. Pencil hardness - JIS K 5400 6.14.Pencil scratch test Peeling test - Cross-cut Cellotape peeling test Visible light transmittance - Model manufactured by Nippon Denshoku Kogyo Co., Ltd.
Measurement of total light transmittance with NDH 1001 DP Example 1 - Printing on hard coat layer - Urethane acrylate-based ultraviolet curable resin paint (Dainippon Co., Ltd. A coating layer with a thickness of 3 μm (dry) was formed by gravure coating with Unidek (manufactured by Ink Kagaku Kogyo Co., Ltd.), and a conveyor speed of 15 m/cm was applied using two high-pressure mercury UV irradiation lamps with an output of 160 W/cm. min
A film having a hard coat layer 2 with a pencil hardness of 3H was obtained. After that, aluminum metal is deposited on the hard coat layer 2 of this film by vacuum evaporation method to a thickness of 0 Å, 10 Å, 30 Å, 50 Å, 100 Å, and 300 Å.
Six types of films having vapor-deposited thin films 3 of 3 were processed. In the case of 0 Å where no deposited thin film was present, corona discharge treatment was performed. After that, vinyl chloride printing ink (VM, manufactured by Dainichiseika Co., Ltd.) is applied to the processed or treated surface of these films.
PEARAL (yellow) 4 was coated in a pattern using the gravure coating method, and the solvent was sufficiently volatilized. As a result, as shown in Figure 1, products with designs on the hard coat surface were obtained. Table 1 shows the results of measuring the peel strength of the designs and the visible light transmittance of areas other than the designs on these products. Shown below.

[Table] Continuous film.
Example 2 - Application to transfer foil - One side of a 38 μm thick polyester film 1 contains a methylated melamine initial condensate and an acidic catalyst.
Anchor coated with a 1:1 solution of toluene and MEK to provide mold releasability using a gravure roll coating method and dried with hot air at 160°C for 30 seconds to form an anchor with mold releasability with a dry film thickness of 0.3 μm. A coating layer 2a was formed to obtain a release sheet. Furthermore, an acrylic urethane-based ultraviolet curing paint is coated on the anchor coat layer 2a by gravure roll coating method, and is cured by irradiating it with ultraviolet light at a speed of 15 m/min using two high-pressure mercury lamps with an output of 160 W/cm. A hard coat layer 2 with a pencil hardness of 3H, a thickness of 2.0 μm, and a visible light transmittance of 90% is formed, and aluminum metal is vacuum-deposited thereon to form a discontinuous vapor-deposited thin film in the form of micro-agglomerates. (thickness: 50 Å) 3 was formed. Thereafter, a polyester solvent-based volatile printing ink (LPEH manufactured by Toyo Ink Co., Ltd.) 4 is coated in a pattern using a gravure coating method, the solvent is sufficiently volatilized, and then a low-temperature adhesive made of vinyl chloride resin and acrylic resin is applied. Hot melt adhesive layer 5
was formed to a dry film thickness of 2.0 μm using a reverse roll coating method. As a result, as shown in Figure 2,
A transfer foil with a pattern was obtained. This is set in an injection mold and transferred at the same time as the acrylic resin 6 is molded, and then the polyester film 1 is peeled off to produce an acrylic resin molded product having a three-dimensional pattern with excellent wear resistance. (See Figure 3). The acrylic resin molded product, which has a hard coat layer 2 with a visible light transmittance of 90% on its surface, has a very decorative pattern with the printing ink 4 clearly embossed on the surface. As shown, the hard coat layer 2 serving as the surface has high hardness and is very stable chemically and physically, so it can be used with good durability. Comparative Example 1 Except for not vacuum depositing aluminum metal,
An acrylic resin molded article was obtained in the same manner as in Example 2. Table 2 shows the results of physical property tests on the surfaces of the acrylic resin molded products obtained in Example 2 and Comparative Example 1.

[Table] As can be seen from the results in Table 2, a very stable molded product was obtained in Example 2, but in Comparative Example 1, in which the printability and adhesion of the surface of the hard coat layer 2 were not improved. It was not possible to obtain a practical molded product. Example 3 - Printing on hard coat layer - A silicon hard coat layer compatible with #0000 steel wool with a pencil hardness of 5H is provided on the surface of a 125 μm thick polyester film, and a vacuum degree of 2 × 10 ^-4 is applied on the hard coat layer. Chromium metal was vacuum-deposited using Thor to form a discontinuous transparent chromium metal thin film with a thickness of 80 Å. Printing ink (Dainichiseika Chemical Co., Ltd.) on this chromium metal thin film
Co., Ltd.'s VM.PEARAL (blue)) is compared to the adhesion strength when no chromium metal thin film is formed and when a 300 Å aluminum metal thin film is further formed by vacuum deposition on the chromium metal thin film. A comparison is shown in Table 3.

[Table] Example 4 - Application of adhesive onto hard coat layer - Silicon Si was vacuum deposited on the same hard coat layer as in Example 1 at a vacuum level of 1 x 10 ^-4 Torr to a thickness of 100 Å. A colorless and transparent discontinuous thin film was formed, a chlorinated polypropylene adhesive was applied on top of the film, and its adhesive strength was tested. The peel test result was 100/100, indicating good adhesion. Note that in this example, the deposited thin film is thought to be SiO _x . Example 5 - Application of adhesive onto hard coat layer - The same procedure as Example 4 was carried out except that nickel was used instead of silicone. In this example as well, the peel test results showed good adhesion of 100/100. Example 6 - Use in transfer foil - An anchor coat layer was formed on one side of a 38 μm thick polyester film in the same manner as in Example 2 to make a release sheet, and then the weight ratio of acrylic/urethane UV curing paint and cellulose was adjusted. Gravure coating was performed using a paint mixed in a ratio of 1:1, and the coated surface was irradiated with ultraviolet light at a speed of 15 m/min using two high-pressure mercury lamps with an output of 160 W/cm.
It was cured to form a transparent resin layer with a film thickness of 2 μm and a pencil hardness of H. Silicon metal was vacuum deposited on the transparent resin layer to form a transparent continuous thin film (SiO _x ) with a thickness of 500 Å. After that, printing ink (VM.PEARAL blue manufactured by Dainichiseika Co., Ltd.) was gravure coated in a pattern on this transparent thin film, the solvent was sufficiently volatilized, and then aluminum metal was vacuum-deposited to a thickness of 350 Å.
Furthermore, a low-temperature adhesive hot melt adhesive consisting of vinyl chloride resin and acrylic resin was applied by reverse roll coating to form an adhesive layer with a dry film thickness of 2.0 μm. As a result, a transfer foil with a pattern on the surface of which a metallic luster was partially exposed after transfer was obtained. This transfer foil is set in an injection mold,
By simultaneously transferring acrylic resin molding,
We were able to obtain an acrylic resin molded product with excellent surface properties and a very interesting three-dimensional pattern with a metallic luster background. Comparative Example 2 An acrylic resin molded product was obtained in the same manner as in Example 6 except that the silicon metal (Si) of Example 6 was not vacuum-deposited. Table 4 shows the physical property test results of the acrylic resin molded products obtained in Example 6 and Comparative Example 2.

【table】

[Table] As shown in Table 4, in Comparative Example 2, the transparent resin layer in the pattern part peeled off during the peel test, and the wear resistance of that part became extremely poor, but in Example 6, the stable acrylic resin layer peeled off. A resin molded product was obtained. Effects of the Invention The present invention can also be applied to the surface of a resin layer having a pencil hardness of H or higher, and in particular, a resin layer having a pencil hardness of 2H or higher, which was previously considered impossible to apply printing ink or adhesive with good adhesion. , it has very good adhesion and allows stable application of printing inks, etc. Furthermore, since the thin film made of an inorganic substance used in the present invention is transparent, the method of the present invention is applied to a transfer foil having a highly hard transparent resin layer, and this transfer foil is used to apply the coating to the transparent resin layer. The printed pattern can be clearly seen through the transparent resin layer, and the transparent resin layer can be transferred with extremely high surface strength. Furthermore, since the present invention can stably provide a sheet having a hard surface with excellent printability and adhesive properties, it has been difficult to stably apply sheets with such a hard surface with good productivity. In addition, it has become very effective in manufacturing touch panels for calculators, word processors, and home appliances.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a sheet showing an example of the present invention;
FIG. 2 is a sectional view of a transfer foil showing another example of the present invention, and FIG. 3 is a sectional view showing an example of use of the transfer foil of FIG. 2. 1...Film, 2a...Anchor coat layer, 2...
Hard coat layer, 3... Vapor deposited thin film, 4... Printing ink, 5... Adhesive layer, 6... Acrylic resin.

Claims (1)

[Claims] 1. 6.14 of JIS K 5400. A hard substrate surface characterized by forming a transparent thin film made of an inorganic substance on the surface of a hard substrate whose hardness is H or higher according to a pencil scratch test. Treatment method to improve adhesion. 2. On the surface of the hard base material whose hardness is 2H or more,
2. The method according to claim 1, wherein the transparent thin film made of an inorganic substance is formed in a discontinuous manner. 3 JIS K 5400 6.14. A hard surface with excellent adhesive properties, characterized by forming a transparent thin film made of an inorganic substance on the hard surface of a sheet having a hard surface with a hardness of H or higher according to a pencil scratch test. sheet with. 4. The sheet according to claim 3, wherein a transparent thin film made of an inorganic substance is discontinuously formed on the hard surface of the sheet having a hard surface having a hardness of 2H or more. 5. Apply JIS K 5400 on the release surface of the release sheet.
6.14. A transfer foil comprising a transparent resin layer having a hardness of H or higher in a pencil scratch test, and a transparent thin film made of an inorganic substance formed on the transparent resin layer. 6. A transparent resin layer having a hardness of 2H or more is provided on the release surface of the release sheet, and a transparent thin film made of an inorganic substance is discontinuously formed on the transparent resin layer. transfer foil.