JPH0441573A - Coating materlial for polylefin sheet - Google Patents

Abstract

PURPOSE:To provide a coating material for a polyolefin sheet which is improved in adhesion to a polyolefin sheet and can provide a coated surface which is less sticky by employing a polyolefin having OH groups at its both ends, a diisocyanate, a specific chain extender and an organic solvent. CONSTITUTION:A polyolefin having OH groups at its both ends (e.g. Epol manufactured by Idemitsu Petrochemical Industries, Ltd.), a diisocyanate (e.g. 1,6- hexamethylene diisocyanate), a diol as a chain extender having an alkyl group in its side chin (e.g. neopentyl glycol) and an organic solvent (e.g. toluene or dimethylformamide) are employed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a coating agent for polyolefin sheets, and more specifically, polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, or ethylene-acrylic copolymer resin. The present invention relates to a coating agent j for polyolefin sheets, which has good adhesion to polyolefin sheets made of polyolefin sheets, and is capable of providing a coated surface with little adhesion.

<Conventional technology and its issues> Conventionally, rosin-modified maleic acid resin, chlorinated polypropylene resin, acrylic resin, nitrified cotton, cyclized rubber, or polyurethane resin have been used as coating agents for polyolefin sheets. .

However, it has been pointed out that all of these have problems such as insufficient adhesion to polyolefin sheets and poor weather resistance and hydrolysis resistance.

<Means for Solving the Problems> As a result of studies conducted by the present inventors in order to obtain a coating agent for polyolefin sheets that solves the above-mentioned conventional problems,
This is what led to this invention.

That is, the present invention provides a coating agent for polyolefin sheets comprising a polyolefin having hydroxyl groups at both ends, a diisocyanate, a diol having an alkyl group in the side chain as a chain extender, and an organic solvent.

<Function> It is known that the polyolefin having hydroxyl groups at both ends, which is used as one of the materials in this invention, has good adhesion to polyolefin sheets and is also excellent in heat resistance and weather resistance.

However, it has very high tackiness, and even with the elastomer obtained by reacting with diisocyanate, it has not been possible to obtain a coated surface with low tackiness as a coating agent.

In addition, if a linear diol is used extensively as a chain extender during the reaction with isocyanate to reduce the adhesion of the painted surface,
There was a tendency for the solubility in solvents to deteriorate and the adhesion to polyolefin sheets to be extremely reduced.

Furthermore, when there is a small amount of linear diol, the adhesiveness is too high and it cannot be used as a coating agent or surface treatment agent.

This invention solves such drawbacks,
When obtaining a urethane elastomer by reacting a polyolefin having hydroxyl groups at both ends with a diisocyanate and a chain extender in an organic solvent, a diol having an alkyl group in the side chain is used as a chain extender in an amount of 3 to 30% (preferably 10-15%).

Such diols include propylene glycol,
Neopentyl glycol, 3-methyl-1,5-bentanediol, ester glycol, bisphenol A, N-
Examples include methyljetanolamine and dimethylolpropionic acid, which can be used alone or in combination.

Further, it is also possible to use a diol having an alkyl group in the side chain together with a linear diol such as ethylene glycol or 1,4-butanediol.

In this invention, the amount of the diol having an alkyl group in the side chain is limited to 3 to 30% of the resin component, because if it is less than 3%, the adhesive strength of the resulting urethane elastomer coated on the polyolefin sheet will decrease. This is because if it is thick (or more than 30%), the adhesion will deteriorate, which is undesirable.

The diisocyanate is not particularly limited (
, 4-methyl m-phenylene diisocyanate, 4,4
゛-Diphenylene diisocyanate, methylene bis 4-
Aromatic, aliphatic, and cycloaliphatic type diisocyanate compounds such as phenyl diisocyanate, 1,4-cyclohexylene diisocyanate, 1,5-hexamethylene diisocyanate, and isophorone diisocyanate can be used.

As the organic solvent, toluene, xylene, methyl ethyl ketone, acetone, dimethyl formamide, etc. may be mixed as desired and used while being careful not to significantly inhibit the dissolution of the film-forming components of the coating agent.

Furthermore, it is also possible to add conventionally known matting agents such as silica, white carbon, and polyethylene fine powder to the coating agent of the present invention, or a hardening agent may be added to accelerate the hardening of the coating film. It is possible. The polyolefin sheets covered with the coating agent of this invention include polyethylene sheets, polypropylene sheets, ethylene-vinyl acetate copolymer sheets, ethylene-acrylic copolymer sheets, ethylene-propylene copolymer sheets, and ethylene-propylene-diene copolymer sheets. Polymerized sheets, etc.

<Example> Hereinafter, this invention will be explained in detail with reference to Examples.

Example 1 Polyolefin having an average molecular weight of 2500 and having hydroxyl groups at both ends (manufactured by Idemitsu Petrochemical Co., Ltd., trade name Meiko Ball) 100
100O, 4 mol), neopentyl glycol 62.4
g (0.6 mol), 1.6-hexamethylene diisocyanate t6sg (1 mol) and 1230 g of toluene were weighed into a reaction vessel, and heated at 90 to 100°C for 4 hours while stirring. During that time, as the viscosity increased, it was diluted with 820 g of dimethylformamide (DMF) and 820 g of toluene. As a result, a coating agent consisting of a 5000 cps/30°C urethane elastomer solution was obtained.

Example 2 500 g (0.2 mol) of 2 balls, 3-methyl 1,5-
Bentanediol 94.4 g (0.8 mol), methylene bis 4-phenylisocyanate 262 g (1 mol)
and 856 g of toluene were weighed into a reaction vessel, and heated at 100 to 110° C. for 6 hours while stirring.

During that time, as the viscosity increased, 572g of DMF and 5g of toluene were added.
A coating agent consisting of a urethane elastomer solution at 3000 cps/30° C. was obtained by diluting with 72 g.

Comparative Example 2 balls 1500 g (0.6 mol) 1,4-butanediol 36 g (0.4 mol), methylene bis-4-phenylisocyanate 262 g (1 mol) and toluene 179
Weigh out 8 g into a reaction container and add 100 to 110 g while stirring.
Heated at ℃ for 6 hours.

During that time, as the viscosity increased, it was diluted with 1198 g of DMF and 1198 g of toluene to obtain a coating agent of 4000 cps/30°C.

Next, the coating agents obtained in Examples 1 and 2 and Comparative Example were coated on an ethylene-propylene copolymer sheet for 30 minutes.
g/+n'' and dried at 100° C. for 1 minute.

As a result, the sheets coated with the coating films made of the coating agents of Examples 1 and 2 had very good adhesion to the coating film, and the coating film had little adhesion.

On the other hand, the sheet coated with the coating film made of the coating agent obtained in the comparative example had high tackiness and poor adhesion to the sheet, and the coating film was easily peeled off with cellophane tape.

<Effects of the Invention> As explained above, the coating agent of the present invention uses a diol having an alkyl group in the side chain as a chain extender, so it has good adhesion to polyolefin sheets (and has low adhesion). It is possible to provide a painted surface.

Claims (2)

[Claims] (1) A coating agent for polyolefin sheets comprising a polyolefin having hydroxyl groups at both ends, a diisocyanate, a diol having an alkyl group in the side chain as a chain extender, and an organic solvent. (2) The coating agent for a polyolefin sheet according to claim (1), wherein the resin component contains 3 to 30% of a diol having an alkyl group in its side chain.