KR100311916B1 - Coating composition for form panel - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a coating composition for a form panel and a formwork panel coated with the composition, and particularly to a composition and a formwork panel coated with a wood formwork panel to impart excellent releasability with concrete to the formwork panel. About

The present invention to achieve the above object a) an acrylic resin; b) polytetrafluoroethylene resin; And c) a film composition for form panels comprising a non-sulfated polyisocyanate compound as a curing agent, and a form panel coated with the film composition.

The formwork panel coated with the formwork composition of the present invention is excellent in releasability with concrete, can be used by increasing the number of reuse in the formwork.

Description

Coating composition for formwork panel {COATING COMPOSITION FOR FORM PANEL}

[Industrial use]

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a coating composition for a form panel and a formwork panel coated with the composition, and particularly to a composition and a formwork panel coated with a wood formwork panel to impart excellent releasability with concrete to the formwork panel. It is about.

[Prior art]

Form panels are form sheets for formwork of concrete structures. The general formwork is to form a form of formwork with formwork panels, injecting slurry-like concrete into the formwork to cure the concrete, and then remove the formwork panel to manufacture the concrete structure.

Such formwork panels are generally used in wood plywood. However, such wood plywood has a problem that when the concrete is hardened and then removed, the surface of the concrete clings to some panels to prevent smooth detachment, as well as the concrete surface is broken to obtain a smooth concrete surface. In addition, in order to reuse the panel, it is necessary to remove concrete stuck to the panel, but the panel is broken during the removal process, so that the panel cannot be reused or the number of reuse of the panel is small.

In order to solve this problem, a method of coating a concrete release agent on the surface of the wood veneer formwork panel, a method of attaching a synthetic resin sheet to the surface of the wood veneer formwork panel, or the material of the formwork panel is made of synthetic resin It has been tried to use as a ash.

Looking at the prior art in detail, in the method of coating the concrete release agent on the surface of the wood veneer formwork panel, the concrete formwork panel coating coated with a solvent-type urethane paint or a solvent-free urethane paint on the surface of the plywood for the concrete formwork panel The use of plywood has conventionally been used.

Compared with conventional solvent type acrylic paints and polyvinylidene chloride paints, the urethane paints have many excellent features such as good working environment, productivity, peelability to concrete, smoothness of the finished surface of concrete molding, etc. It was used a lot. However, in general, the urethane paint before curing has a problem in that the coating film is poorly formed due to the moisture contained in the wooden board when it is weak in moisture and applied directly to the wooden board. In addition, when urethane paint is applied directly to the surface of plywood as a mold substrate, air is introduced into the coating film by air bubbles caused by cracks in the conduit hole or the original plate to form bubbles, resulting in poor smoothness of the surface of the coating film. . In addition, in the case of solvent-free urethane paint, the water contained in the plywood reacts with isocyanate to release carbon dioxide gas, which may result in inferior smoothness or poor curing.

Complementing such a urethane paint, a method of applying a primer coating for coating a resin liquid containing a water-based latex or emulsion, an isocyanate compound and a filler on the bottom, and then coating a urethane paint on the top is described in Korean Patent Application No. 91-5713 It is described. However, the coating film of the urethane paint used in this method is insufficient in the releasability necessary for the concrete panel, so that the concrete can not be removed from the surface of the formwork panel, and the number of reuse of the formwork panel coated with such paint is There was a limit.

In addition, a method of attaching a synthetic resin sheet to a surface of a wood-clad formwork panel has a problem in that the manufacturing process of the formwork panel uses a process requiring a lot of manpower and a number of processes.

In addition, the method of using the formwork panel as a synthetic resin material has a significant difference in the coefficient of thermal expansion with the support wood, causing the phenomenon of curvature on one side of the panel due to the heat of cement hydration and the temperature change of the season during curing of concrete. There is this.

Accordingly, an object of the present invention is to provide a coating composition for formwork panels and a formwork panel coated with the same, which exhibits better releasability with cement when a concrete release agent is coated on the surface of a wood-clad formwork panel in consideration of the problems of the prior art. do.

The present invention to achieve the above object

Acrylic resins; Polytetrafluoroethylene resins; And a non-yellowing polyisocyanate compound as a curing agent.

More specifically, on a solids basis

a) 25-50 parts by weight of acrylic resin;

b) 1.67 to 25 parts by weight of polytetrafluoroethylene resin; And

c) 10 to 20 parts by weight of a non-yellowing polyisocyanate compound as a curing agent

It provides a film composition for formwork panel comprising a.

In the above composition, a curing catalyst may be further added in an amount of 0.001 to 0.01 wt% based on the solid content of the resin and the curing agent in order to shorten the coating film drying time and curing time. This curing catalyst is selected from two or more selected from the group consisting of tetramethylbutanediamine, bicyclooctane, dibutyltindilauryllate, triethylenediamine, zinc octoate and calcium octoate.

The acrylic resin mainly functions as a resin, and it is preferable to use 25 to 50 parts by weight in the composition, at 25 parts by weight or less, film formation and general properties of the film are poor, and at 50 parts by weight or more, excessive crosslinking density is caused. The increase in film formation is reduced.

The polytetrafluoroethylene resin exhibits functions such as breakthrough releasability and chemical resistance to coating film contact materials such as concrete, and in particular, in order to obtain a release effect required for formwork panels, a mixture ratio of acrylic resin and polytetrafluoroethylene resin is required. As for solid content weight ratio, 15: 1-2: 1 are preferable.

When the mixing ratio of the resin is 15: 1 or less, the release effect is lowered, and when 2: 1 or more, the film forming property is lowered.

In addition, the polytetrafluoroethyl resin is preferably a particle size of 10 ㎛ or less. The size of 10 μm or more has a problem in that the dispersibility is poor in preparing the composition, resulting in a decrease in composition productivity and poor storage stability.

The curing agent is used for the purpose of allowing room temperature curing, and a conventional non-yellowing isocyanate capable of reacting with the hydroxyl group of the acrylic resin is preferable, and particularly hexamethylene diisocyanate, isophorone diisocyanate, which has excellent yellowing resistance and light resistance, It is preferable to select at least 1 type from the group which consists of xylene diisocyanate. The amount of the curing agent is preferably 10 to 20 parts by weight based on solids in the composition, and 10 parts by weight or less may cause poor durability due to poor crosslinking properties, and 20 parts by weight or more due to excessive increase in the crosslinking density. The coating film becomes hard.

In addition, the present invention also provides a formwork panel in which the coating composition for formwork panels is coated on the surface of the formwork panel with a dry coating thickness of 10 to 100 µm.

The dry coating thickness is a coating film thickness in which the coating composition is coated and the used solvent is volatilized, and a coating having a thickness of 10 μm or less cannot provide sufficient releasability to a wooden formwork panel having a smooth surface or the like, Coatings of 100 μm or more have low economic value.

The present invention will be described in detail through the following examples and comparative examples. However, the examples are only for illustrating the present invention and are not limited thereto.

EXAMPLE

Example 1

(Preparation of the First Composition)

To 25 g of an acrylic copolymer resin (10,000 molecular weight, 50% by weight of resin solids, and 40 mg of KOH), 5 g of a solvent obtained by mixing butyl acetate and ethyl acetate in a 2: 1 ratio was added and 1000 rpm using a general stirrer. It stirred for 10 minutes at the stirring speed of.

To this stirred solution, 5 g of Benton Paste (10 wt% of Benton) was added as a sedimentation inhibitor, followed by stirring for 10 minutes, followed by 25 g of titanium oxide (TiO ₂ ; It used to disperse | distribute so that the dispersion particle size of a mill base might be 5 micrometers or less.

22 g of the above acrylic copolymer resin was added to the dispersed mill base, 0.02 g of dibutyltin dilaurylate and triethylenediamine mixed solution (weight ratio 1: 1) were added, and 2 g of xylene was added thereto for 10 minutes. Was stirred.

In a separate container, 16 g of polytetrafluoroethylene resin solution was added to the polytetrafluoroethylene resin (Summit Corporation sp-1010) at a weight ratio of 2: 1 and dispersed in a particle size of 10 μm or less using a high speed stirrer. The mixture was stirred for 20 minutes to prepare a first composition.

(Production of Second Composition (Hardener))

6 g of a solvent obtained by mixing butyl acetate and methyl isobutyl ketone 1: 1 in 4 g of hexamethylene isocyanate resin (Bayer's Desmoene-3300) was added thereto, and stirred using a general stirrer at a stirring speed of 1000 rpm for 10 minutes. To prepare a second composition (curing agent).

(Production of Coating Composition)

The film composition was prepared by mixing the first composition and the second composition in a weight ratio of 85:15.

Comparative Example 1

A first composition was prepared in the same manner as in Example 1, except that the first composition was prepared, but the polytetrafluoroethylene resin solution was not added.

The second composition produced the same second composition as in Example 1.

The film composition was prepared by mixing the first composition and the second composition in a weight ratio of 75:25.

Comparative Example 2

A first composition was prepared, but a polytetrafluoroethylene resin solution was added to 3.75 parts by weight based on 100 parts by weight of the first composition, and a first composition was prepared in the same manner as in Example 1.

The second composition produced the same second composition as in Example 1.

The film composition was prepared by mixing the first composition and the second composition in a weight ratio of 85:15.

Comparative Example 3

A first composition was prepared, but the polytetrafluoroethylene resin solution was added to 50 parts by weight based on 100 parts by weight of the first composition, and a first composition was prepared in the same manner as in Example 1.

The second composition produced the same second composition as in Example 1.

The film composition was prepared by mixing the first composition and the second composition in a weight ratio of 85:15.

Example 2

The compositions of Example 1 and Comparative Examples 1 to 3 prepared above were respectively coated under the following coating conditions, and each coating film was compared and tested with comparative items such as adhesion, hardness, chemical resistance, impact resistance, and mold release property. Are listed in Table 1.

(Painting conditions and painting system)

In the dilution method, 10-30 parts by weight of a mixed solvent of butyl acetate, xylene, and methyl isobutyl ketone (weight ratio 1: 1: 1) is added and mixed to 100 parts by weight of the coating composition (a mixed composition of the first composition and the second composition). Each coating composition was diluted with Pod Cup # 4 (25 [deg.] C. temperature) to exhibit a viscosity of 18-25 seconds.

The coating system prepares formwork wooden specimens as a coating material, and coats the two-component urethane primer to have a dry coating thickness of 30 to 35 µm as a coating on the wooden specimen, and the diluted Example 1 to the top coat. And the compositions of Comparative Examples 1 to 3 were coated to exhibit a dry coating thickness of 30 to 35 µm.

(Test Methods)

Adhesion is made in accordance with the recommended coating system by using a razor to cross the test specimens at intervals of 2 mm to reach the surface of the test specimen to make 100 checker marks and press the cellophane tape of Korean Industrial Standard KS A 1528 sufficiently. The peeling state at the time of pulling to 90 degree direction after making it carry out was observed.

Chemical resistance is first evaluated by alkali resistance after dipping each specimen in a 5 wt% aqueous sodium hydroxide solution at 25 ° C. for 24 hours. Second, acid resistance is measured in a 5 wt% sulfuric acid aqueous solution at 25 ° C. It was deposited for 24 hours and then taken out and evaluated. Evaluation was based on the melting of the coating film and no noticeable gloss of the coating film.

The impact resistance was observed by the DuPont tester after the free fall of the 1/2 inch diameter, 500 g weight on each specimen at a height of 30 cm and observed the peeling state of the film, based on the absence of the peeling state.

The hardness was measured by drawing a Misubishi pencil on each specimen.

The releasability was obtained by filtering 75 g of building lime and 225 g of dry sand through a 10 mesh wire mesh to mix well with 100 g of water to prepare a mortar, and then attaching it on each specimen with a thickness of 1.5 cm in an area of 25 cm 2, 38 It was left to stand for 24 hours under the temperature of ° C and the relative humidity of 95%. After leaving, the coating surface and mortar were easily grasped, and the test was repeated 10 times to evaluate the adhesion state of the coating film, the degree of damage of the coating film, and the ease of removing the coating film.

division Example 1 Composition Comparative Example 1 Composition Comparative Example 2 Composition Comparative Example 3 Composition Exterior ◎ ◎ ◎ ○ Adhesion ◎ ◎ ◎ △ Pencil hardness H H H F Chemical resistance Alkali resistance ◎ ◎ ◎ ◎ Acid resistance ◎ ○ ○ ◎ Impact resistance ◎ ○ ○ ◎ Dysplasia ◎ × × ◎

In the table above

The legend ◎ means very good (or 95-100% of the surface area of the coating film).

Legend ○ means good (or 80-94% of the surface area of the coating film is good),

Legend △ usually (or 60-79% of the surface area of the coating film is good),

Legend X means poor (or less than 60% of the surface area of the coating film is good).

Example 3

The compositions of Example 1 and Comparative Example 1 prepared above were respectively coated on the surface of 10 wooden formwork panels of 90 x 120 mm in size under the following coating conditions and dried, and then applied to formwork of a five-layer slab house. It was. After curing for 3 weeks for each layer, it was detached and attached again, and a total of 5 times was used. By the number of times to determine the concrete adhesion degree and release workability and the results are shown in Table 2.

(Painting conditions and painting system)

Dilution method was diluted in the same manner as in Example 2.

The coating system prepares the wooden specimen for formwork as a coating material, and coats the wooden specimen with a two-component urethane primer as a coat using a common roll, so that the dry film thickness is 30 to 35 μm. The diluted Example 1 and Comparative Example 1 compositions were coated in the same manner as shown below to show a dry film thickness of 30 to 35 μm.

division Example 1 Composition Comparative Example 1 Composition Concrete sticking rate when used once (%) ◎ ○ Concrete attachment rate when used twice (%) ◎ ○ Concrete attachment rate when used three times (%) ◎ △ Concrete adhesion rate when used 4 times (%) ◎ △ Concrete attachment rate when used 5 times (%) ◎ × Release workability Great usually

In the table above,

Legend ◎ 95 ~ 100% of the surface area of formwork panel is not attached to concrete

Means no,

Legend ○ shows that 80-94% of the surface area of formwork panel is not attached to concrete.

Means no,

Legend △ shows that 60 to 79% of the surface area of formwork panel is not attached to concrete.

Means no,

Legend X indicates that less than 60% of the surface area of the formwork panel does not have concrete

It means not.

In addition, the mold release workability was judged to be excellent that the mold panel was mold-released by one manual operation, and it is usually represented to work by using auxiliary equipment such as a lever.

As shown in Table 2, the formwork panel coated with the composition of the present invention is very excellent in releasability, almost no adhesion of concrete, and also excellent in release workability, and can be reused by greatly increasing the number of use of the formwork panel.

The formwork panel coated with the formwork composition of the present invention is excellent in releasability with concrete, can be used by increasing the number of reuse in the formwork.

Claims (12)

In the coating composition for formwork panels, On a solid basis a) 25 to 50 parts by weight of acrylic resin; b) 1.67 to 25 parts by weight of polytetrafluoroethylene resin; And c) 10 to 20 parts by weight of a non-yellowing polyisocyanate compound as a curing agent Film composition for formwork panel comprising a. (delete) The method of claim 1, The curing catalyst for drying the coating film and shortening the curing time selected from the group consisting of tetramethylbutanediamine, bicyclooctane, dibutyltindilauryllate, triethylenediamine, zinc octoate or calcium octoate may be used. A film composition for formwork panel, wherein 0.001 to 0.01 wt% of the curing agent is added to the solid content weight. The method according to claim 1 or 3, The film composition for formwork panels for which the mixing ratio of the acrylic resin of said a) and the polytetrafluoroethylene resin of b) is 15: 1-2: 1 by solid content weight ratio. The method according to claim 1 or 3, The coating composition for formwork panels whose particle size of the polytetrafluoroethylene resin of b) is 10 micrometers or less. The method according to claim 1 or 3, A film composition for formwork panels, wherein the non-yellowing isocyanate compound is selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate or xylene diisocyanate as the curing agent of c). In the formwork panel, On a solid basis a) 25 to 50 parts by weight of acrylic resin; b) 1.67 to 25 parts by weight of polytetrafluoroethylene resin; And c) 10 to 20 parts by weight of a non-yellowing polyisocyanate compound as a curing agent Formwork panel formed by coating the film composition for the formwork panel comprising a coating on the panel surface. The method of claim 7, wherein A formwork panel, wherein the formwork coating composition for the formwork panel is coated on the surface of the panel to form a film having a dry coating thickness of 10 to 100 µm. The method of claim 7, wherein The die-coating film composition is shortened drying time and curing time of two or more selected from the group consisting of tetramethylbutanediamine, bicyclooctane, dibutyltindilauryllate, triethylenediamine, zinc octoate or calcium octoate. Forming panel for the curing catalyst is added to 0.001 to 0.01% by weight based on the weight of the solid content of the resin and the curing agent. The method according to claim 7 or 9, The die panel whose mixing ratio of the acrylic resin of said a) and polytetrafluoroethylene resin of b) is 15: 1-2: 1 by solid content weight ratio. The method according to claim 7 or 9, The die panel having a particle size of the polytetrafluoroethylene resin of b) is 10 μm or less. The method according to claim 7 or 9, A die panel wherein the non-yellowing isocyanate compound is selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate or xylene diisocyanate as the curing agent of c).