JPS5834504B2 - Greta - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a lightweight board with excellent writing properties.

Plastic foam boards are used in some displays because they are lightweight and easy to process using a knife coater.

However, because plastic foam boards are hydrophobic, have poor solvent resistance, and have large surface irregularities, their writing properties are extremely poor.

For example, styrene foam is hydrophobic, so when water-based ink or paint is used, it shows poorly, causing repellency and uneven coating, making it impossible to obtain clear transcription.

Also, oil-based inks and paints cannot be used because they will corrode the surface of the styrene foam.

Even if a specially formulated ink or paint that does not corrode the styrene foam and provides good image quality is available, the surface of the styrene foam is highly uneven, so it is extremely difficult to print cleanly.

Furthermore, styrenic foam itself is easily flammable and therefore cannot be used in areas where fire protection is required.

An object of the present invention is to provide a method for producing a lightweight board that has excellent writing properties no matter what type of ink or paint is used, has good surface smoothness, is flame retardant, is lightweight, and is inexpensive.

The method for manufacturing a lightweight board with excellent writing properties of the present invention includes polyvinyl alcohol 10 to 30% by weight based on the resin solid content,
20 to 40% by weight of styrene-butadiene rubber, 70 to 30% by weight of vinyl acetate copolymer, and 2 to 1 inocyanate compounds having two or more functional groups based on the total of the above three components.
It is characterized in that a mixture of an aqueous emulsion adhesive containing 5% by weight and a fine powder inorganic filler corresponding to 30 to 500% by weight of the solid content of the adhesive resin is applied to the surface of a plastic foam board.

The polyvinyl alcohol and histyrene-butadiene rubber used in the present invention may be any of those commonly used as adhesives.

Vinyl acetate copolymers that can be used in the present invention include maleic acid-vinyl acetate copolymers, acrylic acid-vinyl acetate copolymers, and ethylene-vinyl acetate copolymers.

The difunctional or higher incyanate compound used in the present invention means a compound containing at least two isocyanate groups in one molecule, or a compound that liberates at least two isocyanate groups by the action of heat.

The incyanate group reacts with water-soluble polymers and functional groups contained in latex, such as hydroxyl groups, acts as a binder, and has the effect of improving strength and water resistance.

Preferred isocyanate compounds having two or more functional groups include inocyanate compounds such as hexamethylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and compounds having hydrogen active with respect to these incyanate compounds and isocyanate groups. It is a reaction product with.

When the incyanate compound is solid, a solution dissolved in a solvent may be mixed with other adhesive components by stirring.

Good results can be obtained by using a solvent that is not completely miscible with water.

Such solvents include ethyl acetate, toluene, benzene,
Examples include xylene, methyl ethyl ketone, and methyl isobutyl ketone.

These solvents have the effect of uniformly dispersing the incyanate compound in the aqueous emulsion, and the effect of protecting the isocyanate group from water by reducing the contact between the incyanate group and water through an emulsifying action.

Therefore, when an incyanate compound is used, water resistance and strength are improved due to the effect of the binder.

The fine powder inorganic filler that can be used in the present invention preferably has a particle size that can pass through a 350 mesh sieve, and examples thereof include clay, curcum, calcium carbonate, mica, and bentonite.

In the aqueous emulsion adhesive that can be used in the present invention, the polyvinyl alcohol content is 10 to 3 based on the resin solid content.
A three-component polymer containing 0% by weight, 20-40% by weight of styrene-book diene rubber, and 70-30% by weight of vinyl acetate copolymer is required.

The reason for this is to balance applicability to various types of inks with different dispersion media (e.g. water-based, organic solvent-based, alcohol-based, etc.), and each component polymer has its own strengths and weaknesses. Therefore, if one component of the component polymer increases or decreases too much beyond the specified amount, the other two component polymers will not be able to compensate for the defect, and the coating layer will be attacked by the ink. This results in disadvantages in that the ink is likely to bleed, splatter, or fade.

The role played by the isocyanate compound in the present invention is to improve the spreadability of the coating layer to a uniform thickness and the smoothness of the surface.
It is used to maintain the water resistance of the coating layer and the friction and scratch resistance of the layer surface, and it is necessary to use it in an amount of 2 to 15% by weight based on the total amount of the three component resins.

In addition, the role played by the fine powder inorganic filler is to balance the smoothness and slip resistance necessary to make writing easier on the surface of the coating layer, and to provide the smoothness that makes the writing clearer, etc.
It is necessary to use it in a range of 30 to 500% by weight based on the solid content of the adhesive resin, and it is more effective when it is selected in a range of 100 to 500% by weight.

The mixture used in the present invention can include aqueous pigments, flame retardants, and the like.

The plastic foam board used in the present invention is a known plastic foam board such as a polystyrene foam board, a polyurethane foam board, a vinyl chloride resin foam board, a polyethylene foam board, a phenol resin foam board, and the like.

In the present invention, methods for applying the mixture to the surface of the plastic foam board include methods such as using a flow coater, a roll coater, a spray, a brush, a screen, and the like.

The lightweight board made by the method described above (a) is not attacked by most inks, paints, paints, etc., dries quickly, and has almost no repellency or uneven coating, and (b) has good surface smoothness. This allows for better screen printing and painting, (/9 improved punching processability, (2) improved surface strength, (e) improved impact resistance, (f) flame retardancy, (t) ) The surface can be embossed, (
H) By creating a film on both sides of the plastic foam board, there is almost no warping even when exposed to direct sunlight.
The addition of an isocyanate compound has the effect of improving water resistance, heat resistance, oil resistance, and solvent resistance compared to a case without the isocyanate compound.

Since the lightweight board made according to the present invention has the above-mentioned properties, it can be used as displays, indoor/outdoor signboards, teaching materials, building materials, etc.

Comparative Example 1 50 parts by weight of a 10% aqueous solution of polyvinyl alcohol, 25 parts by weight of 50% aqueous latex of styrene-butadiene rubber, 50 parts by weight of 50% aqueous latex of acrylic acid-vinyl acetate copolymer, 50 parts by weight of talc of 350 mesh or less
A mixture consisting of 50 parts by weight of calcium carbonate, 350 meshes or less, and 15 parts by weight of benzidine yellow (yellow pigment) was applied to a polyethylene foam board at a rate of 180 g/m 2 using a reverse coater.

The lightweight board thus obtained was a lightweight board with excellent suitability for oil-based printing inks, paints, water-based colors, magic inks, etc., and excellent writing properties.

Example 1 50 parts by weight of a 10% aqueous solution of polyvinyl alcohol, 25 parts by weight of a 50% aqueous latex of styrene-butadiene rubber, 50 parts by weight of a 50% aqueous emulsion of ethylene-vinyl acetate copolymer, 100 parts by weight of talc of 350 mesh or less
Using a roll coater, a mixture consisting of 100 parts by weight of calcium carbonate of 350 mesh or less, a solution of 5 parts by weight of diphenylmethane diisocyanate dissolved in 10 parts by weight of methyl ethyl ketone, 5 parts by weight of benzidine yellow, and 60 parts by weight of water was foamed using a roll coater. It was applied to a polystyrene foam board with a magnification of 16 times and a thickness of 9 mm at a ratio of 150 g per 17722.

The lightweight board thus obtained was a lightweight board with excellent writing properties, similar to the case of Comparative Example 1.

Examples 2 to 4, Comparative Example 2 Polyvinyl alcohol (Kuraray PVA-117) 1
50 parts by weight of 0% aqueous solution, 25 parts by weight of styrene-butadiene rubber latex (Asahi Dow DL612: solid content 50% by weight), acrylic acid-vinyl acetate copolymer latex (Showa Kobunshi ■Polysol PS-120: solid) 50% by weight
) and 350 meshes or less of talc (Mistron paper) and 1,350 meshes or less of calcium carbonate were each mixed uniformly without settling or gelling, and then the pigment (benzidine yellow) was mixed uniformly without settling or gelling. )1
5 parts by weight and an additional 10 parts by weight of methyl ethyl ketone.
Hexamethylene diisocyanate (Japan Polyurethane Coronate: HL: solid content 75% by weight) was added to each part by weight in the proportions (parts by weight) shown in Table 1, and the emulsion paint obtained by uniformly mixing was foamed. Polystyrene plate (
Asahi Dow ■Wood rack: 10mm thick) using a metallic roll coater. ? It was applied at a rate of 180 g per Z2 and dried at 80° C. for 15 seconds in a hot air circulation dryer.

The results of evaluating the adhesion between the coating layer and the substrate, water resistance, weather resistance, and writing properties of the lightweight board thus obtained are shown in Table 1.

As a result, Examples 2, 3, and 4 were found to have good writing properties, weather resistance, and even better water resistance and adhesion.

Claims (1)

[Claims] 1 Polyvinyl alcohol 10 based on resin solid content
-30% by weight, 20-40% by weight of styrene-butadiene rubber, 70-30% by weight of a vinyl acetate copolymer, and 2-15% by weight of an incyanate compound having two or more functions based on the total of the three components. A lightweight board with excellent writing properties characterized by applying a mixture of an aqueous emulsion adhesive and a finely powdered inorganic filler corresponding to 30 to 500% by weight of the solid content of the adhesive resin onto the surface of the plastic foam board. manufacturing method.