JPH0243464A - Manufacture of surface reinforce concrete-form plywood - Google Patents

Abstract

PURPOSE:To greatly reduce a drying process and prevent the generation of a crack by finish coating the surface of plywood with an ultraviolet curing coating and irradiating same with ultraviolet rays irrespective of the dried/ undried or cured/uncured condition of a filling agent or a primer coating applied to the surface of the plywood. CONSTITUTION:After the surface of plywood is filled with a filling agent while being coated with a primer coating as necessary, the surface is finish coated with an ultraviolet curing coating and irradiated with ultraviolet rays to be cured. In this case, there is no trouble whether the filling agent or the primer coating is in a dried/undried condition or a cured/uncured condition. As for the ultraviolet curing coating, a resin coating of a radical polymerization type acrylate group, a radical polymerization type unsaturated polyester group, a radical addition polythiol polyene, a cationic polymerization type epoxy, etc., are used.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing concrete form plywood whose surface is reinforced with paint.
In the method of manufacturing surface-reinforced concrete form plywood by applying a filler and/or undercoat to the plywood surface and then applying a topcoat, the drying process can be omitted and surface-reinforced concrete is less prone to cracking. This invention relates to a method for manufacturing formwork plywood.

<Conventional technology> So-called surface-reinforced plywood, which is used as concrete formwork plywood by coating the plywood surface with urethane resin paint or acrylic resin paint or pasting a film such as polyethylene film, has been used as formwork plywood for an increased number of times. It is widely used because it prevents the effects of cement hardening inhibiting components that are leached out and improves the surface quality of concrete. Particularly recently, the quality of raw wood for plywood has declined significantly, and surface-reinforced plywood has come into widespread use.

When manufacturing reinforced plywood by painting the plywood surface, it is usually first sealed with a sealant, then an undercoat is applied, dried and sanded, then a top coat is applied and dried again to produce the product. There is.

Many fillers are made by blending fillers such as abrasive powder and pigments with aqueous emulsions of various resins such as vinyl acetate resin and ethylene-vinyl acetate co-condensed resin, and by blending fillers and pigments into oil-based paints. Solvent-based urethane resin paints and solvent-based acrylic resin paints are often used as undercoats and topcoats.

In this case, the paint is usually dried by air drying to prevent foaming on the painted surface, and there is a strong desire to shorten and simplify the drying process. Furthermore, since a solvent-based paint is used, the solvent evaporates during drying and contaminates the air in the workplace, so there is a strong desire for a coating method that does not volatilize the solvent from the standpoint of occupational safety and health.

The use of UV-curable paints as top coats has been considered in order to shorten the drying process, but this has not been put to practical use due to problems with adhesion with base coats and cracks.

<Problems to be Solved by the Invention> As a result of intensive research into a method for manufacturing surface-coated reinforced concrete form plywood using a coating method that simplifies the manufacturing process centered on the drying process, the present inventors have developed a method for producing surface-coated reinforced concrete form plywood. In addition to shortening the drying process by using ultraviolet curable paints, we have also solved the problems of adhesion and cracking, which have traditionally been considered drawbacks, by making it possible for the primer paint or filler to be cured/uncured or dry/undried. The inventors discovered that the problem could sometimes be solved by applying an ultraviolet curable paint for the top coat, leading to the present invention.

Means for Solving the Problems> In the present invention, an ultraviolet curable paint is used as the top coat, and the UV curable paint is applied when the undercoat or filler is cured/uncured or dry/undried to achieve close contact. It was possible to solve the problem of sexual problems and the problem of crack generation.

Examples of ultraviolet curable paints that can be used in the present invention include the following.

(Radical polymerization type acrylate resin paint epoxy)
Acrylic oligomers such as acrylate, urethane acrylate, polyester acrylate, alkyd acrylate, and silicone acrylate, monofunctional or polyfunctional acrylate monomers, and photoreaction initiators such as benzoin ethers, benzophenone, acetophenones, and thioxanthone, and paints whose main ingredients are amine-based auxiliaries and solvents, if necessary.

(2) Radical polymerizable unsaturated polyester resin paint An unsaturated polyester oligomer obtained by polymerizing an unsaturated dibasic acid and a glycol, a styrene monomer, a photoreaction initiator such as benzoin ether, and as necessary. Paints whose main ingredients are auxiliary agents and solvents.

(3) Radical addition type polythiol-polyene resin paint A paint whose main components are an olefinically unsaturated resin (polyene), a polythiol, a photoreaction initiator such as benzophenone, and if necessary, an auxiliary agent or a solvent.

(4) Cationic polymerization type epoxy resin paint A paint whose main components are an epoxy oligomer, a Lewis acid salt as a photoreaction initiator, and, if necessary, an auxiliary agent and a solvent.

Of course, these resins may be used after being modified with various modifiers.

Since materials for concrete formwork are required to have alkali resistance, it is desirable to use urethane-acrylate resins or epoxy-acrylate resins that have excellent alkali resistance.

As an undercoat, vinyl acetate, ethylene, styrene,
Various aqueous emulsion resins, acrylic resins, urethane resins, epoxy resins, alkyd resins obtained by emulsion polymerization of one or more monomers having double bonds such as butadiene and acrylonitriles in an aqueous system,
A paint made of amino resin or the like can be used.

Pigments and fillers are usually added to improve the appearance of the product.

As a filler, fine powder, clay, fine silica, diatomaceous earth,
Fillers such as carbonated lime, rubber powder, pallite, alumina, and wood flour are mixed with water and a binder, and these fillers, pigments, and water or solvent are blended with various resins that can be used as an undercoat. things etc. are used.

The coating method of the present invention is as follows: (1) After sealing the base plywood with a sealant, applying an ultraviolet curable resin paint and curing it by irradiating it with ultraviolet rays; (2) Applying the sealant to the base plywood There are two methods: after sealing the surface, apply an undercoat, and then apply an ultraviolet curing resin coating and cure it using ultraviolet light.

A feature of the present invention is that after applying the sealant and/or undercoat paint, the UV-curable resin paint is applied in a dry/undried or hardened/uncured state, and the UV-curable resin paint is irradiated with ultraviolet rays to cure. It significantly reduces time and improves productivity.

Furthermore, if the conventionally required drying step is omitted by applying the UV-curable resin paint before the filler or undercoat dries, cracking due to stress in the UV-curable resin paint film can be prevented.

Eye cream or lower I:! When UV-curable resin paint is applied to an undried paint, the adhesion improves as the resins dissolve at the interface, so the drying and sanding processes that were previously required can be omitted. This will result in significant rationalization. Furthermore, since UV-curable resin paints are rapidly cured by UV irradiation, stress is generated in the coating film, which tends to cause cracks; however, according to the method of the present invention, after the UV-curable resin paints are cured, the undercoat or eye cream is applied. Because it hardens gradually, this layer relieves stress and makes the product less likely to crack.

Note that adhesion can be further improved by adding a component containing an -NCO group to the filler or undercoat.

<Example> Examples will be described below.

Example-1 (1-1) Preparation of filler Bisphenol A epoxy resin 100 parts (epoxy value 190, viscosity 6000 CPS/25°C) Polyamine curing agent 50 parts (Yuka Shell Epoxy Co., Ltd. 11B-002, amine value 327) Fine powder
150 parts toluene
20 parts were kneaded using a grinder to form a paste.

(1-2) Preparation of UV-curable urethane-acrylate resin 1.3-butylene glycol 135.2 gr (1.5 mol), 1°6-hexanediol 17? ,3gr(1,
5tl) and adipic acid 277.73r (1.9 mol)
Polyester polyol obtained by reacting (equivalent weight: 26
2.5) and tolylene diisocyanate) 383.2gr
and β-hydroxyethyl acrylate 278.4g
A urethane-acrylate resin was obtained by reacting r.

700g of this resin, 300g of trimethylolpropane triacrylate (TMPTA), 40g of benzophenone as a photoreaction initiator, and 35g of 2,5-dimethylaminoethanol were blended to create an ultraviolet curable urethane-acrylate resin paint (paint). 8) obtained.

(1-3) Creation of surface reinforced concrete formwork plywood 12a
After applying 100 gr/& of the sealant prepared in (1-1) to +s thick JAS-type plywood, apply the UV-curable urethane-acrylate resin paint (Paint-A) prepared in (1-2).
Continuous ultraviolet curing equipment (equipment-1) that applied 40 gr/vrr and installed two 80 watt/c UV lamps.
It was cured by passing through the inside at a speed of 5-/1n.

There was no stickiness after curing, and there was no problem when stacking them.

The obtained surface-reinforced concrete form plywood was cured at room temperature for 10 days.

Example-2 (2-1) Preparation of filler Styrene-acrylic resin emulsion 100 parts (manufactured by Kosatsu Gas Kogyo, Begar vL-204, viscosity 5160CP
S/30°C5 resin content 53z) PVA 10% aqueous solution
50 parts (saponification degree 99x5 polymerization degree 17
00) Crude MDI 10
(manufactured by Sumitomo Bayer Urethane, Sumidur 44V-1
0) Fine powder 150 parts water
80 parts were kneaded using a grinder to form a paste.

(2-2) Creation of surface reinforced concrete formwork plywood 12a
1. After applying 120 gr/v/ of sealant prepared in (2-1) to JAS-type plywood of +n+ thickness. The ultraviolet curable urethane-acrylate resin paint (paint-A) prepared in (1-2) was applied at 503 r/Trr, and the inside of the continuous ultraviolet curing apparatus (apparatus-1) was heated at 5 m/sin in the same manner as in Example-1. It was cured by passing it at a speed of .

There was no stickiness after curing, and there was no problem when stacking them.

The obtained surface-reinforced concrete form plywood was cured at room temperature for 5 days.

Example 3 (3-1) Preparation of sealant 100 parts of urethane resin paint (manufactured by Sumitomo Bayer Urethane Co., Ltd., resin content 70%, polyol 07
A mixture of 0.410 parts of isocyanate and 0.7025 parts of isocyanate) 150 parts of fine powder and 150 parts of toluene were kneaded in a crusher to form a paste.

(3-2) Preparation of undercoat 100 parts of polyether polyol (manufactured by Sumitomo Bayer Urethane Co., Ltd., desmodule 1915U1 hydroxyl group content 1.1χ) 21 parts (manufactured by Sumitomo Bayer Urethane Co., Ltd., Desmodur Shi-75, isocyanate group content 13X) to prepare a solvent-free paint.

(3-3) Preparation of UV-curable epoxy resin Adeka Obtomer KR-4 manufactured by Asahi Denka ■ is used as a UV-curable epoxy resin paint using Lewis acid salts as a photoreaction initiator.
00 (Paint-B) was prepared.

(3-4) Creation of surface reinforced concrete formwork plywood 12m
After applying 80g/- of the eye polish prepared in (1-1) to JAS type plywood with a thickness of m, apply 70g/v/- of the urethane resin primer paint prepared in (3-2), and then apply Then, 353r/TIi'' of the ultraviolet curable epoxy resin paint (Paint-B) prepared in (3-3) was applied, and Example-1
5m/m inside the continuous ultraviolet curing equipment (device-1)
It was passed through and cured at a speed of i n .

There was no stickiness after curing, and there was no problem when stacking them.

The obtained surface-reinforced concrete form plywood was cured at room temperature for 10 days.

Example-4 (l) Creation of surface-reinforced concrete formwork plywood 12■■
Filler 8 prepared in (2-1) on thick JAS-type plywood
After applying 0gr//, apply 40gr// of the urethane resin undercoat prepared in (3-2), and then apply (
Apply 40gr/Wr of the ultraviolet curable urethane-acrylate resin paint (paint-containing) prepared in 1-2), and apply 5a+/win in the continuous ultraviolet curing apparatus (equipment ff1-1) in the same manner as in Example-1. It was cured by passing it at a speed of .

There was no stickiness after curing, and there was no problem when stacking φ.The obtained surface-reinforced concrete form plywood was cured at room temperature for 10 days.

Example-5 (5-1) Preparation of filler Styrene-butadiene resin emulsion 80 parts (manufactured by Mitsui Toatsu Chemical, synthetic rubber latex) PVA 10% aqueous solution 20 parts (saponification degree 99z1 polymerization degree 1700) Crude MDI 5 parts (Manufactured by Sumitomo Bayer Urethane, Sumidur 44V-10
) Calcium carbonate 100 parts water
200 parts were kneaded using a grinder to form a paste.

(5-2) Creation of surface reinforced concrete formwork plywood 121
After applying 150 gr/- of the filler prepared in (5-1) to JAS type plywood with a thickness of II11, apply the UV-curable urethane-acrylate resin paint (paint) prepared in (1-2).
A) was applied at 503r/Wr, and the inside of the continuous ultraviolet curing device (apparatus t-1) was heated at 5m/ll1in in the same manner as in Example-1.
It was cured by passing it at a speed of .

There was no stickiness after curing, and there was no problem when stacking them.

The obtained surface-reinforced concrete form plywood was cured at room temperature for 5 days.

Insert 10 rows and 10 rows, stick cellophane tape on top of it, peel it off, and check how it peels off.

(0) Alkali resistance Soaked in 10% caustic soda aqueous solution for one week (c) Repeated cold/heat test - 20°C (2Hrs) - + Repeated heat cycle of 60°C (2Hrs) 6 times.

(d) Concrete releasability JIS R-5201r Physical test method for cement" Mortar prepared according to the method of preparing the specimen was cured on the surface for 2 days.
Repeated times.

The results are shown in Table 1.

The following characteristics were measured for the surface-reinforced concrete form plywood obtained in each of the above examples.

(b) Using a base grain test knife, make a vertical cut in the shape of a 21111x2-1 base grain.
Table 0 Table 1 Table 2 On the other hand, for comparison, commercially available surface-coated reinforced concrete form plywood was tested under the same test conditions. The results are shown in Table 2.

<Effects of the Invention> As described above, the surface-reinforced concrete form plywood obtained by the present invention has excellent adhesion with the base coating material, does not generate cracks even under various conditions, and has excellent releasability from concrete. is also excellent.

moreover, The manufacturing process can be simplified, paint to solvent There is almost no volatilization.

Claims (3)

[Claims] (1) After applying sealant and/or primer paint to the plywood surface,
A method for manufacturing surface-reinforced concrete form plywood by applying a top coat, characterized in that the UV curing resin paint is applied while the filler or paint is in a cured/uncured or dry/undried state. A method for manufacturing concrete formwork plywood. (2) The method for producing concrete form plywood according to claim 1, characterized in that a water-based emulsion resin is used as a sealant and/or an undercoat. (3) The method for producing concrete form plywood according to claim 1 or 2, characterized in that a paint containing an -NCO group is used as the filler and/or the undercoat.