JPH04185671A - Coating of inorganic building material and coating composition - Google Patents

Abstract

PURPOSE:To coat an inorganic building material at low cost at such good efficiency that hand-spraying to its side can be omitted because the side also can be electrostatically sprayed by electrically grounding the substrate and forming a coating film of a primer on it by electrostatic spraying. CONSTITUTION:A coating film of a primer is formed by electrostatic spraying on an electrically grounded inorganic building material (e.g. concrete panel or calcium silicate panel). The coating composition to be used is desirably one based on a urethane resin having an aliphatic or alicyclic isocyanate in the molecule, a chlorinated resin or a (meth)acrylic ester resin. According to the above process, the side of the building material also can be electrostatically sprayed, hand spraying to this side is not necessary, the processing cost can be reduced, and automatic coating is possible by improving the equipment. The film thickness on the top and bottom are uniform, and therefore a high- quality primed foamed concrete panel can be obtained stably.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a coating method and paint suitable for use in factory painting of cellular concrete panels, inorganic building materials such as silica plates, concrete, mortar, etc., especially cellular concrete panels. Regarding the composition.

(Prior art and problem to be solved by the invention) Inorganic building materials such as aerated concrete panels, calc plates, concrete, and mortar are used for the exterior walls of houses. A pre-coating method using concrete is adopted, and aerated concrete panels are particularly frequently used.

JP-A No. 58-45179 discloses that a first layer paint containing urethane resin as a main component and a second layer paint containing acrylic urethane resin as a main component are sprayed onto a suspended cellular cocrete panel by shower-like spraying. After application and drying, a method for applying a top coat is described. However, with the shower spray coating method, the surface facing the shower coat nozzle can be coated, but a sufficient coating film is not formed on the thick side surfaces, requiring manual spray painting and repair painting, which requires more man-hours. The drawback is that it takes a lot of time and processing costs are high,
Aerated concrete panels have air bubbles on their surface, but because capillary action does not work inside the air bubbles, a liquid film is placed over the air bubble openings, making it difficult for paint to flow into the air bubbles. Due to the following reasons, coating film formation is insufficient and waterproofness, especially frost damage resistance, is insufficient.

Furthermore, in order to induce capillary action and flow into air bubbles, it is not effective unless an excessive amount of low-viscosity paint is applied, and when applying to vertically hung panels, the paint does not flow down. Unavoidably, the film thickness becomes uneven between the upper and lower parts of the surface to be coated due to the flow, resulting in insufficient waterproofing in the thin film part at the top and poor drying properties due to the thick film in the thick film part at the bottom. It was inevitable. Therefore, the purpose of the present invention is to enable painting of the side surfaces of inorganic building materials such as aerated concrete panels, to directly inject the paint into the bubbles with small openings and large interiors, and to achieve sufficient coverage. To provide a coating method that reduces the amount of paint flowing down by allowing the paint to enter directly instead of flowing into voids.

Furthermore, in order to make further improvements, by selecting a resin with a specific composition for the undercoat paint, we provide a paint composition that can make the interval between overcoating the undercoat paint free. be.

(Means for Solving the Problems) The present invention is a method of forming a coating film on a grounded inorganic building material to be coated by applying an undercoat paint.

Furthermore, in order to free the interval between coatings of the top coat and the undercoat, we have added a urethane resin (Bl chlorinated resin, (C) (meth) containing an aliphatic or aliphatic diisocyanate in each fA molecule ) This relates to a coating composition containing an acrylic ester resin as a main component.

The present inventor has arrived at the present invention after intensive research on electrostatic coating machines, inorganic building materials, and coating IA characteristics.

The object to be coated used in the present invention is an inorganic building material, and examples thereof include a concrete panel, a Keikal board, concrete, and mortar. Since the present invention is preferably used for factory painting, it is most suitably applied to concrete panels and Keikal boards, especially aerated concrete panels.

In order for an inorganic building material to be electrostatically coated, the moisture content of the building material is preferably 5% or more, more preferably 8%.
That's all. This is because the object to be coated can be grounded by containing a certain amount of moisture.

The static 1i coating used in the present invention is an air atomization method in which the paint is exposed to air, charged, and adsorbed to the object to be coated, or the paint is ejected at a higher pressure than an orifice and the atomized paint is further atomized with air. By airless atomization method.

Depending on the size of the object to be coated, one or more guns may be selected for efficient coating. The applied voltage, the discharge amount, the n-oxidation air amount, the pattern air amount, the gun distance, etc. may be appropriately selected so that a desired coating film can be formed.

By electrostatic*, the atomized paint particles are negatively charged, and they stick to the surface facing the gun due to electrical adsorption, making it difficult to flow, and at the same time, the charged paint particles also circulate to the sides. , a sufficient coating film is formed on the side surfaces as well.

Further, by repeating the cycle in which the particles attached to the object are impregnated from the surface to the inside, and then the next particle is attached, it becomes difficult to flow, and the film thickness on the upper and lower surfaces can be made uniform.

In the bubbles of a cellular concrete panel, paint particles are forced into the bubbles using air. Electric adsorption works on the inner surface of the bubble, and even if a liquid film temporarily forms at the bubble opening, the auxiliary action of pushing the paint into the bubble with air makes it possible to sufficiently coat the inside of the bubble. In factory lines, panel-shaped objects are suspended and moved through the process by chain conveyors, but the objects to be coated are not only vertical, but can also be moved horizontally or horizontally. The present invention can be achieved even in a tilted state.

The undercoating paint used in the present invention is disclosed in Japanese Patent Application Laid-Open No. 58-45179.
Divide the undercoating paint etc. listed in the issue into two parts, and apply the first one.
The undercoat paint is impregnated with urethane resin paint on the object to be coated.
The second undercoat may be a colored pigment and an acrylic urethane resin paint, or the second undercoat may be applied at one time.

In order to further improve the present invention, by using a coating composition in which a specific resin is selected, it has become possible to share the functions of immersion reinforcement, waterproofness, and interval-free performance by utilizing the layer separation effect of the resin. Ta. The coating composition for this purpose is 2(A) below.

(Bl, FC+ is the main component.

Component fA) is a urethane resin containing an aliphatic or alicyclic diisocyanate in 5 molecules.

Examples of aliphatic diisocyanates include trimethylhexamethylene diisocyanate, lysine diisocyanate methyl ester, and dimer acid diisocyanate; examples of alicyclic diisocyanates include hexamethylene diisocyanate, inphorone diisocyanate, and methylcyclohexylene-2,4+2.61- diisocyanate,
1. Examples include H41-(diisocyanatomethyl)cyclohexane and 4,4-bis(incyanatocyclohexyl)methane. Preferred is an alicyclic diisocyanate. Weight average molecular weight is 300 to 10,000
It is.

The blending amount is preferably 3 to 50% by weight, more preferably 20 to 40% by weight based on the resin solid content.

If it is 3% or more, there is an effect of increasing the reinforcing strength of the surface layer by dipping, and if it is 50% or less, interval-free properties can be maintained. (The Al component exhibits the immersion reinforcement effect and interval-free function.

Component (B) is a chlorinated resin.

Examples of the chlorinated resin include vinyl chloride resin, chlorinated polyethylene resin, chlorinated polypropylene resin, chlorinated rubber resin, vinylidene chloride resin, etc. that contain chlorine in the molecule. Preferred are chlorinated polypropylene resin and chlorinated polyethylene resin. The degree of chlorination is preferably 50 to 80%, and the weight average molecular weight is 30.000 to 50.00.
0 is preferred.

The blending amount is preferably 20 to 95% by weight, more preferably 50 to 70% by weight based on the resin solid content.

If it is 20% or more, waterproofness can be maintained, and if it is 95% or less, a synergistic effect with the A1 (C1 component) can be obtained.

Component (B) does not soak into the component fA), but coats the vicinity of the surface layer and functions as a waterproof layer.

The fcl component is a (meth)acrylic acid ester resin. Although the (meth)acrylic ester resin contains an acrylic ester, it does not have a hydroxyl group or a carboxyl group, so it does not crosslink with the fA) component. As a result, the coating film does not become hard, and furthermore, since it is formed in large amounts on the outermost layer, it exhibits an interval-free function.

Examples of acrylic esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, aIn-propyl acrylate, n-butyl acrylate,
Examples include isobutyl acrylate, 2-ethylhexyl acrylate, n-phthyl acrylate, and n-dodecyl acrylate.

Examples of the methacrylic ester include methacrylic esters of the above-mentioned acrylic acids.

These monomers and, if necessary, acrylonitrile,
Obtained from styrene, etc. Weight average molecular weight is 50.00
0 to 150,000. The blending amount is preferably 1 to 20% by weight, more preferably 2 to 20% by weight based on the resin solid content.
It is 10% by weight.

If it is 1% or more, interval-free properties can be maintained, and if it is 20% or less, the paint can exhibit dipability.

Interval-free property means that it does not crosslink with urethane resin (
The effect of adjusting the molecular weight of Bl and IcI components also contributes.

In order to exhibit layer separation of the resin with the coating composition of the present invention, the solubility parameter is controlled.

The coating viscosity of the coating composition of the present invention is adjusted using an organic solvent. The preferred viscosity range is 50 to 1000 centipoise (20°C). The organic solvent to be used is a ketone solvent from the viewpoint of imparting electrostatic properties.

Aromatic solvents are used alone or in combination. Note that, from the viewpoint of reactivity with the urethane resin, alcoholic solvents and amines cannot be used.

In the present invention, an organic/inorganic colored pigment 1-substance pigment can be added depending on the purpose within the range of the pigment volume concentration limit. Furthermore, the combined use of 0.1 to 5% of additives such as surface conditioners and anti-sagging agents in the paint is effective in improving paint performance and coating film performance.

The *hull composition of the present invention may be coated in the required amount at once, or may be coated in two or more consecutive coats. In addition, the top coat can be any solvent-based or water-based top coat that is applied to inorganic building materials as long as there is no problem in adhesion with repeated coats. Also, since there is no recoating interval, it is possible to store the product with the undercoat coated and then apply a topcoat either separately at the factory or on-site. The back side may be the same as the front side, or may be coated with an undercoat by omitting the top coat, and may be coated with a normal water-based paint or, if necessary, an anti-condensation paint.

The coating method of the coating composition of the present invention is based on the electrostatic coating method described above. ! !
! Mounting method is preferable. Further, it is desirable to preheat the object to be coated to a temperature of 20 to 40° C. in order to exhibit coating film performance.

The components of the coating composition of the present invention are mixed using a paint shaker, day silver, ball mill, or sand grind mill that is commonly used in coating production.

A device such as a kneader is used.

The coating amount of the undercoat film is preferably 400 to 800 g/surface area, and the coating amount of the top coat film is preferably 300 to 70 g/surface area.

(Function) According to the present invention, the electrostatically applied paint particles are negatively charged, so that an electrical adsorption force acts on the object to be coated, and (11) the side surface coating due to the paint going around to the side surface is (2) The paint is less likely to flow down, making the paint film uniform on the upper and lower surfaces, and (3) the paint also enters into the surface bubbles caused by air, which helps to push the paint at the entrance, thereby eliminating the bubbles. It is now possible to sufficiently coat the inside of the coating.In addition, by selecting a well-balanced selection of resins with different solubility parameters, it is now possible to control the immersion properties of the object to be coated. The above three functions can be obtained with a single coating by reinforcing it, imparting waterproof properties with a chlorinated resin, and imparting interval-free recoating properties with a (meth)acrylic ester resin.

(Examples) Hereinafter, the present invention will be explained in more detail based on Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples.

An undercoat of the following composition is applied to an aerated concrete panel (size: 90 cm vertically x 90 cm horizontally x 10 cWl thick) suspended from a chain conveyor equipped with air, using an air atomization electrostatic coating machine (Landsbark). After applying aoog/ using an auto R-E-A gun manufactured by Industry Co., Ltd., it was dried at 60° C. for 30 minutes, and the film thickness of (1) the upper surface of the side surface 5 and the lower part of the surface (5) and (2) the amount of water permeation were measured.

In addition, after 1 day and 30 days of drying, apply emulsion coating lHi Vinyrex #70 manufactured by Nippon Paint Co., Ltd. with a brush at 300 ml.
g/rn' After coating, it was dried for 7 days, and adhesion was evaluated using an adhesion tester. The results were extremely good as shown in the table.

The same procedure as in Example 1 was conducted except for the composition of the undercoat. The results were extremely good as shown in the table.

The same procedure as in Example 1 was carried out except that the undercoating paint having the following composition was applied using an air/airless atomizing sieve 1-ite machine (Auto R-E-H-A gun manufactured by Landspark Inkstory). The results were good as shown in the table.

叉"L憇" - The same procedure as Example 1 was carried out except for the composition of the undercoat. The results were as shown in the table.

The same procedure as in Example 1 was conducted except for the undercoat composition. The results were as shown in the table.

Example 1 was carried out in the same manner as in Example 1, except that the coating machine used in Example 1 was changed to a shower coating machine. The results were as shown in the table. -Jth 1 The same procedure as in Example 1 was carried out except that the coating machine in Example 5 was changed to a shower coating machine. The results were as shown in the table.・Evaluation method and evaluation criteria Membrane thickness: Cut the cross section, measure the thickness by manipulating the inspection photograph, and calculate the distribution of membrane thickness (including the layer impregnated in the aerated concrete panel) ( Side surface 1 surface upper part 9 surface lower part) were measured.

Water permeability...JIS A 69105.10 compliant (cc
/75φ-24 hours) Interval-free properties: After undercoating, top coats were applied on the 1st and 30th day, and after drying for 7 days, the state of the fractured surface was observed using an adhesion tester.

(Effects of the Invention) As detailed above, the coating method of the present invention provides
Since the side surfaces can also be covered by f-painting, manual spraying of the side surfaces can be omitted, processing costs can be reduced, and automatic painting can be performed by improving equipment.

By applying electrostatic coating, the thickness of the upper and lower layers can be made uniform, which reduces variations in the finish, dryness, and waterproofness of the board, allowing for stable, high-quality primed aerated concrete panels. Became.

By painting Shizuka 1, the paint particles penetrated into the bubbles, allowing better coverage and improved waterproofness.

Furthermore, with the coating composition of the present invention, interval-free properties were obtained by making the outermost resin layer of the coating film non-crosslinked.

By mixing low-molecular-weight chlorine compound resin and high-molecular-weight (meth)acrylic resin, waterproofness has been improved, making it possible to improve the quality, productivity, and cost reduction of inorganic building materials.

Includes patent questions Nippon Paint Co., Ltd.

Claims (1)

[Claims] 1. An inorganic building material coating method characterized by forming a coating film using electrostatic coating with an undercoat on a grounded inorganic building material object. 2. The following (A) and (B) , (C) as a main component (A) a urethane resin containing an aliphatic or alicyclic diisocyanate in the molecule (B) a chlorinated resin (C) (meth)acrylic acid ester resin