JPH037736A - Production of product of thermoplastic resin having hard coated layer - Google Patents

Abstract

PURPOSE:To obtain the title product having excellent surface hardness and luster by coating the surface of molded article of thermoplastic resin with an ultraviolet-curing resin composition comprising a Michael adduct of a compound containing three or more acryloyl groups with piperidine and curing. CONSTITUTION:The surface of molded article of thermoplastic resin is coated with an ultraviolet-curing resin composition comprising (A) a Michael adduct of a compound (e.g. dipentaerythritol hexaacrylate) containing three or more acryloyl groups with piperidine, (B) a solvent such as methyl ethyl ketone and (C) a photopolymerization initiator such as benzyl dimethyl ketal, dried under heating and irradiated with ultraviolet rays to give the aimed product of thermoplastic resin having a hard coated layer.

Description

Detailed Description of the Invention (a) Object of the Invention (Industrial Field of Application) The present invention relates to a method for manufacturing thermoplastic resin products having a hard coat layer, and more specifically, the present invention relates to a method for manufacturing thermoplastic resin products having a hard coat layer, and more specifically, it has excellent surface hardness and surface gloss, and is suitable for use in automobiles and electrical appliances. The present invention relates to a method for manufacturing thermoplastic resin products having a hard coat layer suitable for use as various industrial components, construction materials, furniture components, etc.

(Prior art) Thermoplastic resins are lighter and easier to process than metals, glass, etc., and have superior appearance such as transparency and gloss, as well as mechanical properties, so they are used as various industrial components for automobiles, electrical products, etc. Widely used.

However, thermoplastic resins generally have poor surface abrasion resistance, and therefore have the disadvantage that they are susceptible to surface damage such as abrasions and scratches due to contact with other objects, depending on the method of use and application.

In order to improve the surface abrasion resistance of thermoplastic resin products, a method has been proposed in which a UV-curable acrylic hard-coating agent such as polyester acrylate, urethane acrylate, or epoxy acrylate is applied to the surface and cured. The low molecular weight compound constituting the agent has a large curing shrinkage when cured by ultraviolet rays, and the curing occurs instantaneously, resulting in a disadvantage that the adhesion of the cured film to the thermoplastic resin is extremely poor.

In addition, in various industrial parts such as automobiles and electrical products, not only film and sheet-like molded products but also various molded products of other shapes are often used, and the surface of such molded products is coated with hard coating. In order to form a layer, a method of applying a hard coating agent to the surface of the molded object by brushing, flow coating, spray coating, dip coating, etc., and then curing it with ultraviolet light;
Alternatively, after applying a hard coating agent to the molding surface and curing it to form a scratch-resistant film in advance, a polymerizable composition that becomes a thermoplastic resin is injected into the mold and polymerized to form a scratch-resistant cured film. Methods have been proposed in which the material is transferred onto the surface of a thermoplastic resin, but each method has the drawback of low productivity.

Furthermore, in order to increase productivity, it is possible to directly thermoform a sheet with an ultraviolet-cured hard coat layer on the surface of a thermoplastic resin product, but in this method, the hard coat layer is already densely crosslinked. This method is also impractical because the hard coat layer cannot follow the elongation of the sheet during molding and cracks.

(Problem of the Invention) The present invention aims to provide a method for producing a thermoplastic resin product having a hard coat layer with excellent adhesion, surface gloss, and scratch resistance.

Another object of the present invention is to provide a method for producing a thermoplastic resin product having a hard coat layer that is laminated and/or thermoformed and has excellent adhesion, surface gloss, and scratch resistance.

Furthermore, the present invention aims to provide a method for producing thermoplastic resin films, sheets, laminates, and various molded products having hard coat layers with excellent adhesion, surface gloss, and scratch resistance.

(b) Structure of the Invention (Means for Solving the Problems) As a result of various studies conducted by the present inventors to solve the above-mentioned problems, the inventors found that: (1) If the ultraviolet curable resin for forming the hard coat layer has a high molecular weight, Curing shrinkage during curing due to ultraviolet irradiation is reduced, and sufficient adhesion to the thermoplastic resin surface is obtained; ■ If the solvent is removed by heating and drying before ultraviolet irradiation, a film is formed and the film is We learned that lamination processing and thermoforming processing can be performed before curing, and that by selecting a high molecular weight UV-curable resin with a large number of acryloyl groups, it is possible to form a hard cord layer with excellent scratch resistance. , has completed the present invention.

That is, the first method for manufacturing a thermoplastic resin product having a hard coat layer of the present invention is to apply a Michael addition compound of (a) a compound having three or more acryloyl groups and piperazine to the surface of a thermoplastic resin molded article. , (b) a solvent, and (c) a photopolymerization initiator.

A second method for producing a thermoplastic resin product having a hard coat layer of the present invention is to add (a) Michael addition of a compound having three or more acryloyl groups and piperazine to the surface of a thermoplastic resin film or sheet. compound, (b)
A thermoplastic resin film or sheet having an ultraviolet curable resin layer obtained by applying an ultraviolet curable resin composition containing a solvent and (c) a photopolymerization initiator and drying it by heating,
This method is characterized by irradiating ultraviolet rays after lamination processing and/or thermoforming processing.

Examples of thermoplastic resins for thermoplastic resin moldings to which the ultraviolet curable resin composition of the present invention is applied include polyolefin resins, methacrylate resins, polycargonates, vinyl chloride resins, ABS resins, and polystyrene. Among these, polyolefin resins, methacrylate resins, and polycargonates are particularly preferred because they have excellent properties such as impact resistance and optical properties, and there is a strong demand for improved scratch resistance.

The polyolefin resins include ethylene-based ones,
Examples include propylene-based ones and mixtures of both. Ethylene-based products include, for example, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, linear high-density polyethylene, ethylene-propylene copolymer, ethylene/vinyl acetate copolymer, and ethylene/acrylic acid copolymer. etc. Examples of propylene-based products include polypropylene, propylene/ethylene copolymer, propylene/butene-1 copolymer, propylene-4-methylpentene-1 copolymer, and maleic anhydride grafted with maleic anhydride. etc.

Among the polyolefin resins, particularly preferred are those based on probile/type. The reason is that zolopyrene resin has better heat resistance than ethylene resin, so when removing the solvent by heating and drying after applying the ultraviolet curable resin composition,
This is because there is little shrinkage due to heat and high surface hardness, so there is little decrease in hardness due to the influence of the base of the formed hard coat layer.

Examples of the methacrylate resin include polymethyl methacrylate and copolymers containing methyl methacrylate as a main constituent unit with other copolymerizable monomers. Examples of the copolymerizable monomer include acrylic esters such as methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate, methacrylic esters such as ethyl methacrylate, and styrene.

Next, the ultraviolet curable resin composition of the present invention comprises (a) a Michael addition compound of a compound having three or more acryloyl groups and piperazine, (b) a solvent, and (c) a photopolymerization initiator. However, compounds having three or more acryloyl groups that are raw materials for producing the Michael addition compound as the zero component include, for example, trimethylolzolo-guntriacrylate, ethylene oxide-modified trimethylolpropane triacrylate, and propylene. Oxide-modified trimethylolpropane triacrylate, trimethylolpropane tetraacrylate, tris(acryloquinoethyl)in cyanurate, caprolactone-modified tris(acryloxyethyl)in cyanurate, pentaerythritol triacrylate, di- pentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, alkyl-modified pentaerythritol)
Examples include alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol tetraacrylate, caprolactone-modified dipentaerythritol hexaacrylate, and mixtures of two or more of these. Among these, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, and mixtures thereof are preferred because they provide a coating layer with particularly excellent scratch resistance.

A Michael addition compound of a compound having three or more acryloyl groups and piperazine can be produced by reacting the two using a solvent, preferably the solvent used as component (b). The reaction molar ratio of the compound having three or more acryloyl groups to viperacin in the reaction is preferably in the range of 1 to 1.3. If this reaction molar ratio is less than 1, dulling will occur during the reaction, and if it exceeds 1.3, the formed Michael addition compound will be liquid, so the ultraviolet curable resin composition will form a film after the solvent dries. become unable.

The amount of the solvent used in this reaction is preferably within a range such that the weight ratio of (compound having three or more acryloyl groups + piperazine)/solvent is 0.01 to 0.3.

If the ratio is less than 0.01, the reaction product (ie, Michael addition compound) will contain a large amount of solvent, which will require a large amount of energy to remove, which is uneconomical. If the ratio exceeds 0.3, dulling occurs during the reaction, which is undesirable. However, of course, after the reaction of a compound having three or more acryloyl groups with piperazine, K and the solvent are removed to make the ratio 0.3 or more.
There is no difference.

This reaction is carried out at 0 to 100°C for 1 hour to 1 week, preferably at 20 to 50°C for 1 hour to 1 day.

In addition, as the solvent for component (b), 3 acryloyl groups are used.
Aromatic hydrocarbons such as toehabenzene, toluene, xylene, ethylbenzene, cumene, acetone, methyl ethyl ketone, methyl isobutyl ketone, diimbutyl Examples include ketones, ketones such as cyclohexanone, ethers such as tetrahydrofuran, dioxane, methyl cellosolve, and mixtures of two or more thereof. Solvents that cannot be used alone but can be used in combination with the above solvents or their mixed solvents include alcohols such as methyl alcohol, ethyl alcohol, isozorobyl alcohol, methyl acetate, ethyl acetate, butyl acetate, etc. Examples include esters.

In addition, examples of the copolymerization initiator for component (c) include benzoin methyl ether, benzoin ethyl ether,
Benzoin isopropyl ether, benzoin butyl ether, jetoxyacetopheno/, benzyl dimethyl ketal, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, benzophenone, Michler's ketone, isoamyl N,N-dimethylaminobenzoate , 2-chlorothioxanthone, and two or more of these photopolymerization initiators can be used in combination as appropriate. The amount of photopolymerization initiator used is component (a) 100
0.1 to 10 parts by weight, preferably 1 to 5 parts by weight
Parts by weight.

If necessary, the ultraviolet curable resin composition may contain, for example, an acryloyl group-containing compound (for example, urethane acrylate, epoxy acrylate, polyester acrylate, etc.) within a range that does not impair film-forming properties, and a compound that inhibits polymerization due to heat during storage. thermal polymerization inhibitors (for example...
hydroquinone, high-F quinone monomethyl ether, catechol, pt-butylcatechol, phenothiazine, etc.), ultraviolet absorbers (e.g. benzotriazole ultraviolet absorbers), ultraviolet stabilizers (e.g. hindered amine ultraviolet rays) to improve the physical properties of the coating. stabilizers), antioxidants (e.g. hindered phenolic antioxidants),
Furthermore, in order to improve the physical properties of the coating film, thermoplastic resins (e.g. polyurethane resins, polyester resins, acrylic resins, vinyl chloride resins, etc.), anti-blocking agents, slip agents, leveling agents, etc., which are dissolved in the same composition, are added. Various additives that can be blended into products (13) can be blended.

The ultraviolet curable resin composition in the present invention may be applied directly to the thermoplastic resin molded body, but if necessary, the surface of the thermoplastic resin molded body may be washed, etched, corona discharged, irradiated with active energy rays, etc. It may be applied after pre-treatment. When coating a film or sheet-like molded article, it is desirable to use a coating machine capable of uniformly and smoothly coating, such as a roll coater-die coater.

When the thermoplastic resin molded article coated with the ultraviolet curable resin composition is heated and dried to remove the solvent, an ultraviolet curable resin layer is formed on the surface of the thermoplastic resin molded article. The thickness of the resin layer is 1 to 50 μm, preferably 3 μm in dry film thickness.
~30μ.

Next, the thus obtained dried thermoplastic resin molded body having the ultraviolet curable resin layer is exposed to an ultraviolet generation source,
For example, when exposed to ultraviolet light for 1 to 60 seconds using a xenon lamp, low-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, carbon arc lamp, tungsten lamp, etc., it will easily harden and improve the adhesion and surface A thermoplastic resin product having a hard coat layer on the surface with excellent gloss and scratch resistance can be obtained.

Further, in the present invention, the thermoplastic resin film or sheet having the ultraviolet curable resin layer obtained as described above is laminated with other thermoplastic resins and/or thermoformed, and then irradiated with ultraviolet rays. You can also.

In this case, the lamination processing method includes a method of laminating the thermoplastic resin film or sheet having the ultraviolet curable resin layer obtained as described above with another base material using an adhesive, or a method of laminating the thermoplastic resin film or sheet having the ultraviolet curable resin layer obtained as described above with another base material, or a method of normally used extrusion. This can be done by laminating the thermoplastic resin sheet with another thermoplastic resin sheet that has been heat-melted and kneaded in a machine and extruded into a sheet form from a T-die by applying pressure between rolls using the heat during extrusion. Alternatively, the thermoplastic resin film or sheet having the ultraviolet curable resin layer obtained as described above can be obtained by separately heating and melting kneading various types of thermoplastic resins and coextruding them from a single T-die. When laminated with a multilayer sheet, a multilayer laminate can be obtained in one extrusion process.

Further, as a thermoforming processing method, the thermoplastic resin sheet having the ultraviolet curable resin layer obtained as described above or the above-mentioned laminate may be processed using a vacuum forming machine equipped with a desired mold, a pressure forming machine, Using a molding machine such as a vacuum-pressure molding machine or a hot plate pressure-forming machine, the thermoplastic resin is heated and softened to the optimum temperature depending on the type of resin, and then immediately brought into close contact with the mold surface using vacuum and/or compressed air and cooled. By doing so, a molded product having a desired shape can be obtained.

If the laminated and/or thermoformed molded product obtained by these methods is irradiated with ultraviolet rays in the same manner as described above, a laminated product having a hard coat layer with excellent adhesion, surface gloss, and scratch resistance can be obtained. and/or a thermoformed thermoplastic resin article is obtained.

(Examples, etc.) K, Examples and Comparative Examples will be further described below. In these examples, "parts" and "%" mean parts by weight and % by weight, respectively.

Example 1 15 parts of dipentaerythritol hexaacrylate and 72 parts of bicarbonate were dissolved in 40 parts of methyl ethyl ketone.
The Michael addition reaction was carried out at ℃ for 3 hours. 0.5 part of benzyl dimethyl ketal was dissolved in the product to obtain an ultraviolet curable resin composition.

This ultraviolet curable resin composition was applied to a corona discharge-treated polypropylene sheet (60 degree gloss of 71%, pencil hardness of HB) with a thickness of 1.211K so that the coating thickness after drying was 10
After applying it so that it becomes μ and drying it for 2 minutes at 80℃,
We used an irradiation device with a high-pressure mercury lamp with an output of 2 kW and a power density of 80 W/[ installed perpendicular to the sample passing direction.
The coating film was cured by UV irradiation at the cy+ position at a conveyor speed of 2 m/min.

The adhesion of the cured coating film to the polypropylene sheet can be determined by using a cutter to make 100 cuts in the shape of base lines at 1 part intervals, pressing cellophane adhesive tape onto the cuts, and then peeling it off strongly ( When tested using a cellophane adhesive chip peel test, the adhesive was 100/100 and did not peel off at all, indicating sufficient adhesion. In addition, this sheet has a 60 degree gloss level of 90% (JIS z8741) and a pencil hardness of 3H.
(JIS K 5401) It was excellent in terms of hardness, surface gloss, and surface hardness.

Example 2 8 parts of dipentaerythritol hexaacrylate, 8 parts of dipentaerythritol pentaacrylate, and 2 parts of dihydrazine were subjected to a Michael addition reaction in 4 parts of ethyl alcohol and 78 parts of toluene at 50°C for 3 hours. 0.5 part of benzyl dimethyl ketal was dissolved in this product to obtain an ultraviolet curable resin composition.

This ultraviolet curable resin composition was applied to a polymethyl methacrylate sheet (60 degree gloss 82%, pencil hardness 2H) with a thickness of 1111 so that the coating thickness after drying was 10μ. ? After drying for 2 minutes, the coating film was cured by irradiation with ultraviolet rays under the same conditions as in Example 1.

The obtained cured coating film was subjected to the same test as in the example, and the results were as follows.

Cellophane adhesive tape peel test 100/10060 degree gloss 94% pencil hardness
6H Example 3 15 parts of dipentaerythritol pentaacrylate and 2 parts of piperazine were subjected to a Michael addition reaction in 43 parts of methyl ethyl ketone and 40 parts of toluene at 50°C for 3 hours.

0.5 part of benzyl dimethyl ketal was dissolved in the product to obtain an ultraviolet curable resin composition.

This ultraviolet curable resin composition was applied to polycarbonate (60 degree gloss 80%, pencil hardness 4B) in order of thickness so that the coating thickness after drying was 10μ, and dried at 80°C for 2 minutes. After that, the coating film was cured by irradiating ultraviolet rays under the same conditions as in Example 1.

The obtained cured coating film was subjected to the same test as in Example 1, and the results were as follows.

Example 4 The ultraviolet curable resin composition obtained in Example 1 was applied to a polyzolopyrene film having a thickness of 40 μm that had been subjected to corona discharge treatment.
Apply so that the coating thickness after drying is 10μ, and heat at 80℃.
and dried for 2 minutes.

A polypropylene film having this ultraviolet curable resin composition layer, 30% polyzolobile, 45% high density polyethylene with a specific gravity of 0.95, and talc 2 with an average particle size of 5μ
By melt-kneading a resin composition consisting of 5% in an extruder at 230°C and extruding it to a thickness of 2.8 mm, the sheet is laminated by applying pressure between rolls using the heat during extrusion. A laminated sheet was obtained.

This laminated sheet was irradiated with ultraviolet rays under the same conditions as in Example 1 to cure the ultraviolet curable resin composition layer.

The obtained cured coating film was subjected to the same test as in Example 1, and the results were as follows.

Pencil hardness B Lead cage hardness H Example 5 The ultraviolet curable resin composition obtained in Example 1 was mixed with a polypropylene layer (50μ), 30% polypropylene, 45% high density polyethylene with a specific gravity of 0.95, and an average Particle size 5μ
A corona discharge-treated laminated sheet consisting of two layers (2.8 m1) of a resin composition layer (2.8 m1) of 25% talc (60 degree gloss 71%, pencil hardness HB) K, coating thickness after drying of 1
It was coated to a thickness of 0μ and dried at 80°C for 2 hours.

A laminated sheet having this ultraviolet curable resin composition layer,
Mold (height 801m, width 200fil, depth 150il
Using a pressure forming machine equipped with 1), heat the surface temperature of the sheet to 165°C with a heater, and then mold the sheet so that the area magnification (area after molding/area before molding) is 2.87. I got the item.

This molded article was irradiated with ultraviolet rays using the same apparatus as in Example 1 at a conveyor speed of 0.8 m 2 /min to cure the ultraviolet curable resin composition layer. The obtained cured coating film was subjected to the same test as in Example 1, and the results were as follows.

Cellophane adhesive tape peel test 100/10060 degree gloss 95% pencil hardness
2H Example 6 The ultraviolet curable resin composition obtained in Example 1 was applied to a 40μ thick polypropylene film treated with corona discharge.
It was applied so that the coating thickness after drying was 10 μm, and dried at 80° C. for 2 minutes.

A polypropylene film (A) having this ultraviolet curable resin composition layer, a resin composition (B) consisting of 99.8% polypropylene and 0.2% aluminum powder with an average particle size of 25μ, and polypropylene 30%, specific gravity 0 .95
A resin composition (c) consisting of 44.7% of high-density polyethylene, 25% of talc with an average particle size of 5μ, and 0.3% of carden black was melt-kneaded at 230°C in separate extruders. The layer (B) is 50
μ, layer (c) is co-extruded with a thickness of 2.8n, and the heat during extrusion is used to press between rolls to form layers (A), layer (B), and A laminated sheet was obtained in which layers (c) were laminated in this order.

This laminated sheet was heated to a surface temperature of 165°C with a heater using a pressure molding machine equipped with a mold (height 80 mm, width 200 mm, depth 15 mJ), and then the area magnification (
A molded product was obtained by molding so that the ratio (area after molding/area before molding) was 2.87.

This molded article was irradiated with ultraviolet rays under the same conditions as in Example 5 to cure the ultraviolet curable resin composition layer. The obtained cured coating film was subjected to the same test as in Example 1, and the results were as follows.

Cellophane adhesive tape peel test 100/10060 degree gloss 95% lead cage hardness
2H Example 7 The ultraviolet curable resin composition obtained in Example 1 was
It was coated on polycarbonate (60 degree gloss 80%, lead turtle hardness 4B) so that the coating thickness after drying was 10 μm, and dried at 80° C. for 2 minutes.

This polycarbonate having the ultraviolet curable resin composition layer was put into a mold (height: 80 mm, width: 200 mm, depth: 150 mm).
11) Using a pressure forming machine equipped with a heater, the surface temperature of the sheet was heated to 185°C, and then molded so that the surface magnification (area after molding/area before molding) was 2.87. A molded product was obtained.

This molded article was irradiated with ultraviolet rays under the same conditions as in Example 5 to cure the ultraviolet curable resin composition layer. The obtained cured coating film was subjected to the same test as in Example 1, and the results were as follows.

Cellophane adhesive tape peel test 100/10060 degree gloss 94% pencil hardness
HB Comparative Example 1 An ultraviolet curable resin composition was obtained by dissolving 2 parts of benzyl methyl ketal in 98 parts of dianttaerythritol hexaacrylate.

This ultraviolet curable resin composition was applied to the corona discharge-treated polyzoropylene sheet (1.2 sheets thick) used in Example 1.
60 degrees, gloss level 71%, pencil hardness HB), coating thickness 1
The coating film was coated so as to have a thickness of 0μ, and the coating film was cured by irradiating ultraviolet rays under the same conditions as in Example 1.

When the obtained cured coating film was subjected to a cellophane adhesive tape peeling test, it was found to be O/100 and the cured coating film had no adhesiveness at all. In addition, since the UV-curable resin composition itself is liquid, the coating film before UV irradiation is
Neither lamination processing nor thermoforming processing could be performed.

Claims (5)

[Claims] (1) An ultraviolet curable resin consisting of (a) a Michael addition compound of a compound having three or more acryloyl groups and piperazine, (b) a solvent, and (c) a photopolymerization initiator on the surface of a thermoplastic resin molded body. A method for producing a thermoplastic resin product having a hard coat layer, which comprises applying a composition, heating and drying it, and then irradiating it with ultraviolet rays. (2) On the surface of the thermoplastic resin film or sheet, (a
) An ultraviolet curable resin composition consisting of a Michael addition compound of a compound having three or more acryloyl groups and piperazine, (b) a solvent, and (c) a photopolymerization initiator is applied and then heated and dried. A method for producing a thermoplastic resin product having a hard coat layer, which comprises laminating and/or thermoforming a thermoplastic resin film or sheet having a curable resin layer and then irradiating it with ultraviolet rays. (3) The manufacturing method according to claim 1 or 2, wherein the thermoplastic resin is a polyolefin resin, a methacrylate resin, or a polycarbonate. (4) The manufacturing method according to claim 1, 2, or 3, wherein the compound having three or more acryloyl groups is dipentaerythritol hexaacrylate and/or dipentaerythritol pentaacrylate. (5) Claims 1 and 2, wherein the Michael addition compound is a compound obtained by Michael addition of a compound having three or more acryloyl groups to piperazine at a molar ratio of 1 to 1.3;
The manufacturing method according to claim 3 or claim 4.