JPH0330913A - Paint composition for concrete form ply wood - Google Patents

Abstract

PURPOSE:To give good demolding properties by a method wherein a specified amount of spherical polyethylene resin particles having the specified particle diameter is added to paint. CONSTITUTION:To 100 pts.wt. of solid content of paint, 0.5-50 pts.wt. of spherical polyethylene resin particles having the average particle diameter of 1-80mum is added. As for the paint used for base, no special limitation is present or any one of solvent type paint, crosslinking type paint, water-based paint, ultraviolet curing type paint and the like, all of which are generally used as organic surface finishing paint, can be used. As the spherical polyethylene resin particle, spherical resin particle made of low density polyethylene, high density polyethylene or ultra-high-molecular-weight polyethylene can be preferably used. In order to apply paint composition to ply wood stock, publicly known painting method such as roll coating, knife coating, transfer coating by spraying, screen coating or the like can be used.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel coating composition for concrete formwork plywood, more specifically, for concrete formwork used for pouring mortar for construction and civil engineering, and for hardening and curing. The present invention relates to a coating composition that is applied to plywood to impart particularly good demoldability.

[Conventional technology] Conventionally, in forming plywood for concrete, it has been important that the concrete surface has good finished smoothness and surface gloss, but if plywood is used as is, the sugar content in the plywood wood This causes problems such as poor curing of the concrete due to molding, discoloration of the concrete due to resin, and undesirable situations due to insufficient durability of the formwork plywood itself.

Therefore, in order to solve these problems and further improve the finished smoothness and surface gloss of the concrete surface, painted formwork plywood, in which the contact surface of the formwork plywood with the mortar is coated with paint, is often used. There is.

Such painted formwork plywood has conventionally been coated with solvent-based paints such as acrylic lacquer, acrylic/urethane-based, polyester/urethane-based, and chlorinated polyolefin-based paints.

However, in such conventional coated formwork plywood, the coating film is made of a relatively low molecular weight resin that is made into a polymer through a cross-linking reaction, so intramolecular aggregation is generally weak, and the plywood cannot be used as concrete formwork plywood. When used, problems arise such as low mechanical strength and poor chemical durability.

For this reason, when conventional coated formwork plywood is used for concrete pouring, the surface of the concrete formwork is soaked due to the physical impact during pouring, the heat of hydration, the alkaline components of the cement mixture, moisture, etc. This often leads to undesirable situations such as poor demolition, discoloration of concrete, and poor curing. In particular, when the painted formwork plywood is repeatedly used for concrete pouring, its demoldability is sharply reduced, and the number of times it can be repeatedly poured is inevitably limited.

Conventionally, in order to improve demoldability during concrete pouring, it has been common practice to apply a liquid mold release agent such as mineral oil or silicone to the coated formwork plywood for concrete using a brush or roller bucket. However, this effect can only be obtained with one-time pouring, and the effect of increasing the number of repeated pouring of concrete form plywood is not very effective. Additionally, depending on the mold release agent applied, it may deteriorate due to sunlight, causing discoloration of the concrete or poor curing, or may cause problems such as corroding the paint film of the painted formwork plywood and causing poor demoldability. There are many.

On the other hand, in order to improve the removability of the coating film itself of painted formwork plywood for concrete, hydrocarbon-based lubricants such as paraffin,
It is known to use organic lubricants such as fatty acids such as lauric acid, metal soaps such as calcium stearate, and silicone-based lubricants, but they may not have sufficient alkali resistance or water resistance, or may have poor coating film strength. It is effective to greatly improve the number of repeated uses for pouring concrete-coated formwork plywood, such as decreasing the lubricity or losing the lubricity imparting effect after one or two repeated uses because it is blended into the surface. few.

[Problems to be Solved by the Invention] Under these circumstances, the present invention provides a method for applying concrete formwork plywood used for pouring and curing mortar for construction and civil engineering to achieve particularly good demolding. The purpose of this work was to provide a coating composition for imparting properties.

[Means for Solving the Problems] The present inventors have conducted intensive research to develop a coating composition that can be applied to concrete formwork plywood and impart good demoldability. A composition made by blending a specific amount of polyethylene spherical resin particles with a diameter into a paint,
We have found a way to achieve the above object, and based on this knowledge, we have completed the present invention.

That is, in the present invention, for 100 parts by weight of paint solids,
The present invention provides a coating composition for concrete form plywood, characterized in that it contains 0.5 to 150 parts of polyethylene spherical resin particles having an average particle diameter of 1 to 80/7 m.

The present invention will be explained in detail below.

In the coating composition of the present invention, there are no particular limitations on the base coating, including solvent-based coatings, cross-linked coatings, water-based coatings, etc., which are commonly used as organic surface finishing coatings.
Any UV-curable paint can be used.

Examples of such paints include acrylic lacquers, polyurethane paints, vinyl chloride resin paints, solicon resin paints, and urethane acrylate and polyester acrylate UV-curable paints.

In the coating composition of the present invention, polyethylene spherical resin particles having an average particle diameter of 1 to 80 μm are used as the demoldability imparting agent. Such polyethylene spherical resin particles are
When added to paints, it imparts lubricity to the surface of the paint film, greatly improving demoldability during concrete pouring, and is chemically stable and has excellent water resistance, chemical resistance, and especially alkali resistance and resistance. It has impact resistance and resists physical impact during concrete pouring.
Since the durability of the coating film against heat of hydration, alkaline components of cement mixtures, moisture, etc. is greatly improved, the number of repeatable castings that can be used can also be greatly improved. Moreover, the polyethylene spherical resin particles have good dispersion stability and smooth fluidity, so that a coating composition with excellent paintability can be provided.

In the present invention, it is necessary that the average particle diameter of the polyethylene spherical resin particles is in the range of 1 to 80 μm.

If this average particle diameter is less than 1 μm, particles tend to aggregate,
There is a risk that sufficient dispersion into the paint will be difficult, and
If it exceeds μm, it tends to settle when added to a paint, making it difficult to obtain a homogeneous paint film, and tends to cause undesirable situations such as the painted surface becoming rough and the particles peeling off. For this reason, especially when the average particle diameter is 5~
Polyethylene spherical resin particles in the range of 30 μm are preferably used.

In the composition of the present invention, the polyethylene spherical resin particles must be blended in an amount of 0.5 to 150 parts by weight, preferably 2 to 50 parts by weight, based on 100 parts by weight of the solid content of the paint. If the blending amount is less than 0.5 parts by weight, the effect of improving the removability of the coating film will not be sufficiently exhibited, and if it exceeds 150 parts by weight, the homogeneity of the coating film will decrease and the resin particles will easily peel off and fall off. I can see a tendency towards this.

As the polyethylene spherical resin particles used in the present invention, spherical resin particles of low density polyethylene, high density polyethylene, ultra-high molecular weight polyethylene, etc. can be suitably used.

The paint composition for concrete formwork plywood of the present invention may optionally contain additive components conventionally used in paint compositions.
For example, pigments, leveling agents, antioxidants, lubricants, etc. can be added.

In order to apply the coating composition of the present invention to a plywood material, known coating methods such as a roll coater, knife coater, spray transfer coating, and screen coater can be used.

Although the coating composition of the present invention may be applied directly to the plywood material, it is preferable to treat the plywood with a primer coating, such as a sealant, which is widely used in the formwork plywood industry. It is desirable to apply the coating composition of the present invention.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

Example 1 Commercially available acrylic lacquer for concrete formwork [Niacrite No. 500 gray NVM = 42% manufactured by Nippon Oil & Fats Co., Ltd.
, P/B=0.1) and 100 parts by weight of low-density polyethylene spherical resin particles (manufactured by Steel Chemical Industry Co., Ltd.: Flow Beads LE-1080, average particle size 16 μm) to weight were mixed and dispersed to form a paint. A composition was obtained.

A commercially available urethane sealant [manufactured by NOF Corporation: urethane undercoat gray, urethane hardener Y, base agent/hardener weight ratio -20/
After applying l) with a knife coater, the above coating composition was applied with a roll coater to a coating density of 1509/m'' and dried by heating at 40°C for 30 minutes to create coated formwork plywood for concrete. lko.

Comparative Example 1 A painted formwork plywood for concrete was prepared in the same manner as in Example 1, except that the acrylic lacquer was not blended with polyethylene spherical resin particles.

Example 2 Commercially available acrylic/urethane paint for concrete formwork [manufactured by NOF Corporation: Urethane No. 500 Gray, NV
M = 58%, P/B-0,2) 100 parts by weight, high-density polyethylene spherical resin particles [Steel Chemical Industry Co., Ltd.
Co., Ltd.: Flow Beads HE-5023, Average Grain Convention 20
μm]30 parts by weight were mixed and dispersed to obtain a paint composition product.

For 100 parts by weight of the above coating composition,
Hardening agent [manufactured by NOF Corporation: Urethane hardening agent Y, NC
After mixing parts by weight of O%-30% and NVM-100%]io, the mixture was applied to a sealed form plywood in the same manner as in Example 1 using a roll coater so that the coating amount was 120ti/m. It was coated and dried by heating at 50°C for 45 minutes to create coated formwork plywood for concrete.

Comparative Example 2 A painted formwork plywood for concrete was prepared in the same manner as in Example 2, except that the acrylic/urethane paint did not contain polyethylene spherical resin particles.

Example 3 Commercially available ultraviolet curable paint for concrete IJ formwork [manufactured by NOF Corporation: Beam Coat CP Clear NVM-97%
) to 100 parts by weight of ultra-high molecular weight polyethylene spherical resin particles [manufactured by Mitsui Toatsu Co., Ltd.: Mibellon MX-220, Average Particle Convention 22. um) was mixed and dispersed to obtain a coating composition.

The above coating composition was applied to the sealed form plywood in the same manner as in Example 1 using a roll coater in a coating amount of 50 g/m2.
After applying it, UV irradiation was performed using two high-pressure mercury lamps with an output of 80 W/cm at a distance of 2 cm from the formwork plywood and a conveyor speed of 2 m/min to create a concrete coating and formwork plywood. tko.

Comparative Example 3 In Example 3, 0.1 part by weight of polyethylene spherical resin particles was blended with 1001 parts by weight of the ultraviolet curable paint.
;Other than that, painted form plywood for concrete was prepared in the same manner as in Example 3.

A box-shaped formwork was made using the painted formwork plywood for concrete created in Examples f to 3 and Comparative Examples 1 to 3, respectively.
Cement mortar prepared by adjusting the water/cement ratio of ordinary Portland cement to 0.57 is placed in the formwork, and the temperature is 25.
After curing for 5 days at °C1 relative humidity 75RH%, the concrete was demolded and the finished appearance of the concrete surface after demolding was evaluated.

The formwork after demolding was lightly washed with water and then dried, and the same operation as above was repeated, and the number of repeated uses until cracking of the formwork plywood, peeling of the surface layer, etc. occurred was recorded. Table 1 shows the finished appearance of the concrete and the number of times the form plywood was used repeatedly, that is, the number of times it was repurposed.

From the results shown in Table 1, it can be seen that concrete form plywood prepared by applying the coating composition of the present invention can be used more frequently.

[Effect of the invention] The coated form plywood for concrete made using the coating composition of the present invention has a smoother coating surface than that made by applying the conventional paint composition for concrete form plywood. It has excellent alkali resistance and water resistance, and is resistant to cement mixtures and moisture during concrete pouring.
It has the advantage of being easy to remove from the mold when repeatedly cast as a coated form plywood for concrete, and can be used for a large number of repeated castings.

Claims (1)

[Claims] 1 Average particle size 1 to 8 per 100 parts by weight of paint solid content
A coating composition for concrete form plywood, characterized in that it contains 0.5 to 150 parts by weight of 0 μm polyethylene spherical resin particles.