JPS5933129B2 - Method for manufacturing synthetic resin molded products with surfaces with excellent wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a synthetic resin molded article having a surface with excellent abrasion resistance.

Synthetic resin products manufactured from polymethyl methacrylate, polystyrene, polycarbonate, etc. and molded into various shapes are lighter than glass products and have excellent impact resistance, and can be manufactured quickly and at low cost. It is used in many fields because it has various advantages such as:

However, synthetic resin molded products made from these synthetic resins lack surface hardness, so the surface may be damaged by contact with other objects, collisions, or scratches, resulting in poor appearance. The optical properties are deteriorated and the value of the product is significantly reduced. Up to now, various studies have been made to improve the drawbacks of such synthetic resin molded products.
For example, a cross-linked curable resin material that imparts abrasion resistance is applied to the surface of a thermoplastic synthetic resin molded product that has been previously molded into the shape of the final product, and the cure of the applied material is completed to create a thermoplastic synthetic resin molded product. A method of imparting abrasion resistance to a material, or a method of forming a film of a polymer of a cross-linked curable resin material on the inner surface of a mold in advance, and then injecting a base resin raw material and polymerizing it to bond the base material and the film. A method has been proposed in which a thermoplastic synthetic resin plate is imparted with wear resistance by being integrated and peeled from a mold, and then molded to obtain a synthetic resin molded product. However, the above method has major drawbacks as described below, and therefore is not yet of sufficient practical use.

In other words, in the former method, when applying a cross-linked curable resin material to a synthetic resin molded product that has been molded to its final form, the application process is extremely complicated compared to polymerization applied to a plate-shaped product. It is complicated, and it is difficult to make the coating thickness uniform. On the other hand, in the latter method, the thickness of the applied film can be made more uniform than in the former method, but the film is formed by polymerization, which involves molding a plate-shaped synthetic resin with a cross-linked cured film on the surface into the final product. Because it is highly cross-linked, the moldability of the synthetic resin is limited by the limit of film elongation, and if molding is carried out under conditions that exceed the film's elongation limit, cracks will occur in the film. This will seriously damage the appearance and make it unusable.

Generally speaking, the harder the coating is with better abrasion resistance, the smaller the elongation will be, and the moldability of the synthetic resin will be worse. Therefore, it has been difficult to mold a synthetic resin plate-like article having a hardened film with excellent wear resistance on its surface into its final form and to produce a desired synthetic resin molded article. The inventors of the present invention adopted a special method as a result of intensive research in order to eliminate these drawbacks and develop an efficient method for manufacturing synthetic resin molded products having a crosslinked film on the surface with excellent wear resistance. As a result, we have found a method that can solve these problems all at once, and have completed the present invention.

The gist of the present invention is to apply a radically polymerizable cross-linked curable resin material that imparts wear resistance to the surface of a thermoplastic synthetic resin plate, and to irradiate the coated material with ultraviolet rays on the surface of the plate. The synthetic resin plate-shaped article having the pre-cured coating material is then molded, and the pre-cured coating material is then irradiated with ultraviolet rays to post-cure. The present invention provides a method for producing a thermoplastic synthetic resin molded article having a surface with excellent wear resistance.

A thermoplastic synthetic resin plate-shaped article (hereinafter simply referred to as a plate-shaped article) used in the present invention.

) has a thickness of 0.05 to 50 mm, preferably 1 to 50 mm, and is manufactured by various commonly used molding methods such as cast polymerization, injection molding, compression molding, and extrusion.
Polymethyl methacrylate, copolymers of methyl methacrylate, methacrylic resins such as polycyclohexyl methacrylate, polystyrene,
The thermoplastic synthetic resin is selected from styrene resins such as AS resin and ABS resin, polycarbonate, hard vinyl chloride, cellulose resins such as cellulose acetate and cellulose acetate butyrate, and unsaturated polyester. Among these, resins particularly suitable for carrying out the present invention include methacrylic resins, polycarbonates, polyallyl diglycol carbonates, styrene resins, etc., which have high transparency and good appearance.

The radically polymerizable crosslinked curable resin material (hereinafter referred to as crosslinked curable resin material) used in the present invention is not particularly limited, but from the viewpoint of curability and coating film properties, polyfunctional ethylenically unsaturated monomers are used. mass, e.g. Special Publication 1977
-26507 and Japanese Patent Publication No. 49-36830, cross-linked polymerizable compounds having at least two or more acryloyloxy or methacryloyloxy groups in one molecule, or three or more in one molecule. Examples include condensation-reactive monomers having a condensation-reactive functional group.

Main examples of cross-linked polymerizable compounds having two or more acryloyloxy or methacryloyloxy groups in one molecule include polyhydric alcohols and (meth)acrylic acid (acrylic acid and/or methacrylic acid, hereinafter referred to as acrylic acid and/or methacrylic acid). (same) as a condensate.

Examples of saturated polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propanediol, butanediol, hexanediol, trimethylolethane, trimethylolpropane, pentaerythritol, and the like. Examples of crosslinked polymerizable compounds obtained from these and (meth)acrylic acid include ethylene glycol di(meth)acrylate, triethylene glycol dimethacrylate, tetraethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, Propanediol di(meth)acrylate, Butanediol di(meth)acrylate, Hexanediol di(meth)acrylate, Bis(ethylene glycol)
Examples include phthalate di(meth)acrylate, pentaerythritortetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, and trimethylolethane tri(meth)acrylate.

These crosslinking polymerizable compounds can be used alone or as a mixture thereof.

In addition, these cross-linked polymerizable compounds are mixed with other copolymerizable monomers, acrylic acid, methacrylic acid, esters thereof, acrylonitrile, methacrylonitrile, styrene and derivatives thereof, preferably these monomers. It can also be used as a mixture containing up to 30% by weight. Among the cross-linked polymerizable compounds mentioned above, in order to highly increase the surface hardness and abrasion resistance of synthetic resin molded products, three or more acryloyloxy groups or methacryloyloxy groups per molecule should be added to the resin material applied to the surface of the plate-shaped product. Compounds with groups such as pentaerythritol tetra(meth)
It is preferable to use a material containing 30% by weight or more of acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, or the like. As a polymerization initiator for curing the above-mentioned crosslinked polymerizable compound, commonly used peroxides such as benzoyl peroxide and lauroyl peroxide, or azo compounds such as azobisisobutyronitrile, or a main absorption wavelength Photosensitizers having a wavelength of 2,500 to 4,000 λ, particularly preferably benzoin or its alkyl ether (having 1 to 4 carbon atoms). The amount of the polymerization initiator added is 0.1 to 10 parts by weight per 100 parts by weight of the crosslinked polymerizable compound.
Preferably it is 0.3 to 2 parts by weight. On the other hand, specific examples of monomers having three or more condensation-reactive functional groups in one molecule include tetraalkoxysilane, methyltrialkoxysilane, phenyltrialkoxysilane, vinyltrialkoxysilane, and γ-methacroxysilane. Tetravalent or trivalent silicon compounds such as propyltrialkoxysilane,
Alternatively, melamine compounds such as etherified methylolmelamine may be used.

During the condensation reaction of the silicon compound or melamine compound, the reaction is usually carried out in the presence of an acidic catalyst such as hydrochloric acid or P-toluenesulfonic acid as a curing accelerator.

Stabilizers, modifiers,
Third substances such as colorants, flame retardants, etc. can also be added.

To carry out the present invention, first, the crosslinked curable resin material is applied to the surface of a plate-shaped article, or the plate-shaped article to be coated is heated.

In order to further improve the adhesion between the cured film and the plate-shaped article, it is often preferable to adopt the latter method. Examples of the method for applying the crosslinked resin material to the plate-shaped article include brushing, spin coating, spray coating, flow coating, dip coating, roll coating, gravure coating, bar coding, screen coating, air knife coating, and other methods. It will be done.

The thickness of the crosslinked curable resin material to be applied can be arbitrarily selected depending on the purpose of use, but from the viewpoint of surface hardness, impact resistance, optical properties, etc., it is generally 0.001 to 1 mm, preferably 0.001 to 1 mm. It is desirable to apply the coating to a thickness of 0.1 m7n. Next, the crosslinked curable resin material applied to the surface of the plate-shaped article is precured.

The degree of preliminary curing must be such that the coated material is at least hardened to the extent that the surface will not become sticky and the surface will not be damaged during the process of forming the plate-shaped product, and There are no particular limitations as long as two conditions are satisfied: when post-curing is performed after molding, the cure must not be to such an extent that no progress in curing can be observed. However, for the purposes of the present invention, it is desirable that the degree of preliminary curing be carried out to a stage where the surface hardness is comparable to that of the plate-shaped article that is the base material, and that the curing be stopped at that stage. As a precuring method, a conventional polymerization method is used for both coatings made of a cross-linked polymerizable compound and coatings made of a condensation-reactive monomer.

In the case of a cross-linked polymerizable compound, a method of adding a thermal polymerization initiator as described above and heating preferably at a temperature of 50°C or higher and below the heat deformation temperature of the base material of the plate-like article, or a method of heating at room temperature or above room temperature and the base material. A method of adding a photosensitizer as described above and irradiating active light at a temperature below the heat distortion temperature of the material, or a method of irradiating radiation such as gamma rays, etc. can be applied. Among these polymerization methods, considering the curing speed, simplicity of equipment, and safety, it is recommended to add a photosensitizer and irradiate active light from a xenon lamp, low-pressure mercury lamp, high-pressure mercury lamp, or ultra-high-pressure mercury lamp. It is desirable to polymerize and cure the resin. When curing the coated material by the above method, it is preferable to eliminate the polymerization inhibiting effect of oxygen. For example, the method of using an inert gas atmosphere such as nitrogen gas, carbon dioxide gas, rare gas, combustion gas, etc. or reducing the pressure, or the synthesis of polyolefins, polyesters, etc. that have a smooth flat film or plate shape. A method of covering with an article made of a material such as resin, glass, stainless steel, or aluminum or a method of covering with a cylindrical glass is used. When coating an article with a film, plate, or cylindrical shape and curing the coating with actinic rays, the article to be coated must be transparent to actinic rays, such as polyolefin, polyester, or glass. In some cases, it is possible to irradiate actinic light through the coating, but when using an opaque coating such as stainless steel,
Actinic light must be irradiated through the plate-shaped substrate. In carrying out the present invention, it is preferable to use a continuous method in which the plate-shaped product is manufactured by continuous extrusion molding or continuous cast plate manufacturing until the completion of pre-curing, and then a cross-linked curable resin material is applied and pre-cured. . Forming of a plate-like article having a precured coating on its surface can be carried out in the same manner as when the plate-shaped article does not have a coating on its surface.

For example, air circulation heating furnaces, infrared ray furnaces, and air convection furnaces are used to produce female and male molds that are designed to obtain the desired shape of a molded product when heated to an appropriate temperature using a local heater, etc. Alternatively, the desired shape can be formed by bending, single curved surface molding, free blowing, free press, pressing, vacuum forming, etc. using a male and female mold. However, at this time, it is necessary to carry out the process within the limit elongation of the pre-cured coating material, and if the coating material is elongated beyond the critical elongation limit, the coating material will crack and cannot be used for practical purposes. . After molding a plate-shaped article having a precured coating material on its surface, curing of the coating material can be completed in the same manner as the method for precuring the coating material. In the case of post-curing, since no further molding is performed, it is desirable to carry out sufficient curing. In the case of this post-curing, unlike the case of pre-curing, it is extremely complicated to cover with an article having a film, plate, or cylindrical shape, so it is necessary to remove the polymerization inhibiting effect of oxygen. For this purpose, it is preferable to cure under an inert gas atmosphere or under reduced pressure. Alternatively, in the pre-cured state, the polymerization inhibiting effect of oxygen is greatly reduced compared to before pre-curing, so in consideration of simplifying the equipment, curing may be carried out in the atmosphere. preferable. As described above, the feature of the present invention is that the cross-linked curable resin material is cured in two stages, and the first stage cures the material to make it smooth and smooth at the stage of hardening where sufficient moldability remains. By forming a coating film surface and imparting sufficient abrasion resistance after molding through the second stage of curing, it is possible to mold into complex shapes with excellent abrasion resistance that were previously impossible. The goal is to make it possible to industrially manufacture synthetic resin molded products.

These synthetic resin molded products, which have excellent abrasion resistance and are molded into complex shapes, are used for lighting supplies such as fluorescent light covers and streetlight covers, instrument covers and watch glasses, and display equipment. , case, etc., and is widely used in synthetic resin molded products that require wear resistance. Hereinafter, the present invention will be explained in more detail with reference to Examples.

In Examples, parts represent parts by weight.

Example 1 A methacrylic resin plate with a thickness of 3 m1 was heated to 65°C in a composition liquid consisting of 20 parts of 1,6 hexanediol diacrylate, 80 parts of trimethylolethane triacrylate, and 1.5 parts of benzoin ethyl ether. The sample was immersed in water for 3 minutes, pulled up at a speed of 50 cm per minute, and irradiated for 3 seconds with a Toshiba high-pressure mercury lamp H4OOOL/3 in a nitrogen stream.

The thus obtained methacrylic resin plate having precured coating films on both sides had no flow patterns, dust, distortion, etc., and had a beautiful appearance similar to the methacrylic resin plate before treatment.

The coating thickness at this time was 28 microns on both sides.
The gel content of the coating was 86.3%. The gel content was measured by the following method. A sample (weight W.y) from which the cured film has been peeled off from the plate-like base material is immersed in acetone at 50°C to elute the dissolved content, and then dried to a constant weight (dry weight Wly) to obtain the following formula: Find it by The pencil hardness of the laminate thus obtained was 2H, the same as that of the methacrylic resin plate before treatment. The laminate obtained by pre-curing was heated to 140
℃ and molded into a single curved surface using male and female wooden molds for molding single curved surfaces with flannel attached to the surface.

The molding radius of curvature (hereinafter referred to as R) was gradually decreased, and the R at which cracks occurred on the coating surface was measured. No cracks occurred when R was 40 mm, but cracks occurred when R was 30 mm. The R4O dragon laminate molded product obtained by heat molding was irradiated in the air with a Toshiba high pressure mercury lamp H4OOOL/3 for 2 minutes.

The thus obtained molded product has a pencil hardness of 8H, which shows excellent abrasion resistance, and R4Om77! It was a laminated molded product with excellent moldability. Mark 1 Clam 111 A composition liquid consisting of 20 parts of 1,6 hexanediol diacrylate, 80 parts of trimethylolethane triacrylate, and 1.5 parts of benzoin ethyl ether prepared by heating a 3 mm thick methacrylic resin plate to 65°C. The sample was immersed in the solution for 3 minutes, pulled up at a speed of 50 cm per minute, and irradiated for 2 minutes with a Toshiba high-pressure mercury lamp H4OOOL/3 in a nitrogen stream to obtain a laminate having a pencil hardness of 8H.

When this laminate was heated to 140°C and made into a single curved surface using male and female wooden molds, no cracks occurred when the radius was 150 mm.
However, cracks occurred at 125 mm.

As in Example 1, it was completely impossible to mold to 40 mmf)R. Example 2 A composition solution consisting of 100 parts of trimethylolpropane triacrylate and 1 part of benzoin methyl ether was applied to a bisphenol-A polycarbonate resin plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Iupilon") with a thickness of 2 m and 71 L,
A polyester film with a thickness of 38 microns was placed on top of it, and it was spread out so as not to leave any air bubbles.
Irradiated for seconds.

The treated side of the laminate obtained by peeling off the polyester film had a pencil hardness of 4B, while the untreated side had a pencil hardness of 4B.

The thickness of the coating film at this time was 21 microns, and the gel content of the coating film was 72.8%. When the thus obtained laminate was heated to 180°C and molded into a single curved surface using male and female wooden molds with the treated surface facing outward, no cracks occurred when the radius was 10m71L, and the radius was 5m7! Cracks occurred in L.

A laminated molded product with R of 10 dragons was irradiated for 5 minutes with an Eikosha water-cooled high-pressure mercury lamp PlH3OOO in a nitrogen stream.
A molded product with a pencil hardness of 8H and excellent abrasion resistance could be obtained.

On the other hand, regarding the formability of the laminate that was cured to a pencil hardness of 8H before forming, no cracks occurred when R was 300 mm, but cracks occurred when R was 200 mm, making it impossible to form.

Example 3 A continuous acrylic resin plate with a width of 700 mm and a thickness of 4 mm, which is continuously fed at a speed of 2 m/min, was coated with pentaerythritol tetraacrylate 50 whose bottom part was kept at 60°C.
One side of a U-shaped tank filled with a composition liquid consisting of 1,4 parts, 45 parts of 1,4-butanediol diacrylate, 5 parts of methyl methacrylate, 2 parts of benzoin isopropyl ether, and 0.5 parts of monomethyl etherified hydroquinone. The laminate having a coating film of the above-mentioned composition liquid on both sides was continuously supplied from the opening, and the laminate having a coating film of the above-mentioned composition liquid on both sides was continuously taken out from the other opening.
The laminate was irradiated with O for 2 seconds from both sides to obtain a laminate having a continuously precured coating film.

The pencil hardness of this treated laminate is 2H, the coating thickness is 35 microns on both sides, and the gel content is 84-7.
It was %. The single curved surface forming limit R of the above laminate is R = 5
No cracks occurred in the case of 0 Dragon, but cracks occurred in the case of R of 407 f1m, making it impossible to form.

The molded product with R of 5011, which could be molded, was irradiated for 2 minutes in the air with an ultra-high pressure mercury lamp CHM33OO manufactured by Oak Seisakusho, to obtain a molded product with a pencil hardness of 7H.

On the other hand, regarding the formability of the laminate that was cured to a pencil hardness of 7H before forming, no cracks occurred when R was 600 mm, but cracks occurred when R was 450 mm, making it impossible to form. Example 4 30 parts of trimethylonolepropane triacrylate and 7 parts of neopentyl glycol diacrylate were added to an endless bisphenol-A polycarbonate tree with a width of 700 mm and a thickness of 2 mm that was continuously fed at a speed of 2 m/min.
A composition solution consisting of 0 parts of benzoin butyl ether, 1 part of benzoin butyl ether, and 0.2 parts of 2-methylanthraquinone was applied, and the resin plate was pressed with a stainless steel drum with a radius of 1 m and a mirror surface made of stainless steel. While keeping it in contact with the drum, heat it with a Toshiba high pressure mercury lamp H2OOO through the resin plate.
Irradiated for 0 seconds.

The pencil hardness of the laminate thus obtained was 4B and 18
When molding a single curved surface at 0° C., no cracks occurred when R was 10 mm, and cracks occurred when R was 511 m, making molding impossible.

RlOm7! When the laminated molded product formed into L was irradiated with a Toshiba high-pressure mercury lamp H2OOO for 5 minutes in the air, the pencil hardness was 7H.

On the other hand, it is hardened to a pencil hardness of 7H before molding,
The moldability of the laminate is R is 1507! t1! When R was 100 mm, cracks were generated and molding was impossible.

Example 5 Thickness 6. A methacrylic resin plate of 1.0 mm in diameter was immersed for 3 minutes in a solution containing 50 parts of trimethylolethane triacrylate, 50 parts of tetraethylene glycol, and 1.5 parts of benzoin isobutyl ether heated to 70°C, and the
The sample was lifted up at a speed of 1.5 cm and irradiated for 1 minute with a Matsushita fluorescent chemical lamp FLR6OEH in a nitrogen stream.

The laminate with this pre-cured coating has a pencil hardness of 2
Regarding the single curved surface forming limit R at 150° C., when R was 30 mm, no cracks occurred, but when R was 25 mm, cracks occurred and forming was impossible.

A molded product with a radius of 30 mm that could be molded was irradiated for 5 minutes with an ultra-high pressure mercury lamp CHM33OO manufactured by Oak Seisakusho in a nitrogen stream to obtain a product with a pencil hardness of 8H.

On the other hand, when the material was hardened to a pencil hardness of 8H before molding, no cracks occurred with R6OOmm, but with R45O
mm, cracks occurred and molding was impossible.

Claims (1)

[Claims] 1 A radically polymerizable crosslinked curable resin material that imparts wear resistance is applied to the surface of a thermoplastic synthetic resin plate, and the coated material is precured by irradiating ultraviolet rays onto the surface of the plate to make it smooth. forming a coating film surface, then molding the synthetic resin plate-like article having the pre-cured coating material, and then post-curing the pre-cured coating material by irradiating it with ultraviolet rays. A method for manufacturing thermoplastic synthetic resin molded products that have a surface with excellent abrasion resistance.