JPH0759648B2 - Polyurethane / Polyurea molded products Painted products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a polyurethane / polyurea molded article coated product used for automobile numbers, wind gaskets and the like.

[Conventional technology]

Conventionally, polyurethane molded product coatings used for automobile numbers, wind gaskets, etc. are molded products by reaction injection molding (hereinafter abbreviated as RIM method) using polyhydric alcohols such as ethylene glycol and propylene glycol as chain extenders. And is coated with urethane paint.

Generally, when a polyhydric alcohol is used as a chain extender, the molding time is as long as about 5 minutes and the production efficiency is low. In order to improve this, a method of using an aromatic polyamine instead of the polyhydric alcohol as a chain extender, a method of using an internal mold release agent, or a combination of these methods has been proposed. It is described in JP-A-60-245622. When an aromatic polyamine is used as a chain extender, the molding time is shortened to about 1 minute, and the combination of an internal mold release agent significantly shortens the molding cycle, resulting in high production efficiency.

[Problems to be solved by the invention]

However, the surface of a coated article of a molded article obtained by coating a polyurethane / polyurea molded article obtained by using an aromatic polyamine as a chain extender with a urethane-based coating is likely to be discolored by sunlight or heat. As a result of intensive studies to solve this problem, the present inventors have found that it is possible to produce a polyurethane / polyurea molded article coated product with high production efficiency, a smooth coating film surface and little discoloration. Completed the invention.

[Means for Solving the Present Invention]

The present invention provides (a) a molecular weight of 1800 to 12000 and a terminal primary conversion ratio of 9
0% or more of polyether polyol or mixture thereof (b) aromatic polyamine and (c) catalyst, blowing agent, 0.1 to 1.
A polyurethane produced by the RIM method from an active hydrogen-containing composition containing 0 part by weight of a hindered phenolic stabilizer and, if necessary, other auxiliaries, and a modified diphenylmethane diisocyanate (hereinafter abbreviated as modified MDI) composition. / It relates to a polyurethane / polyurea molded product coated with a urethane-based coating material on the polyurea molded product.

The polyether polyol in the active hydrogen-containing composition used in the present invention has a molecular weight of 800 to 12000 obtained by adding ethylene oxide and propylene oxide to a starting material such as propylene glycol and glycerin, and has a terminal 1
The grade is 90% or more. Usually, when propylene oxide is added, the terminal hydroxyl group becomes secondary and the reactivity with the isocyanate group becomes low, and when ethylene oxide is added, the terminal hydroxyl group becomes primary and the reactivity with the isocyanate group becomes high. It is also possible to mix and use a starting material, a polyether polyol having a different ratio of ethylene oxide and propylene oxide, a molecular weight, a number of functional groups and the like.

As the chain extender, an aromatic polyamine and, if necessary, a polyhydric alcohol are used.

As the aromatic polyamine, 1,3,5-triethyl-2,6-
Diaminobenzene, 3,5,3 ', 5'-tetraethyl-4,4'
-Diaminodiphenylmethane, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene and the like are used.
-Methyl-3,5-diethyl-2,4-diaminobenzene and / or 1-methyl-3,5-diethyl-2,6-diaminobenzene are preferred. If necessary, the polyhydric alcohol may be a diol such as ethylene glycol, propylene glycol, butanediol, diethylene glycol or dipropylene glycol, a triol such as glycerin, trimethylolpropane or hexanetriol or a compound or amine compound thereof as a starting material. A polyether polyol having a molecular weight of 500 or less, to which ethylene oxide and / or propylene oxide is added, is used. The ratio of polyhydric alcohol to aromatic polyamine is 0 to 20 parts by weight to 80 to 100 parts by weight.

As the catalyst, triethylamine, N-methytylmorpholine, N-ethylmorpholine, bis (N, N-dimethylaminoethyl) ether, 1,4-dimethylpiperazine, triethylenediamine, N, N, N ', N',- Tetramethyl-
A tertiary amine such as 1,3-butanediamine or an organometallic compound such as dibutyltin dilaurate or stannas octoate is used.

As the foaming agent, in addition to water, halogenated hydrocarbon, etc., nitrogen, air, etc. dissolved in the active hydrogen-containing composition under pressure are also used.

As a hindered phenolic stabilizer, 2,6-di-ter
0.1 to 100 parts by weight of t-octylphenol, 2,6-diisobutylphenol, 2,6-di-tert-butyl-4-methylphenol (hereinafter abbreviated as BHT)
Used in 1.0 parts by weight. The preferred hindered phenol stabilizer is BHT, and when the amount is 0.1 parts by weight or less, the surface of the coating film is likely to be discolored, while when it is 1.0 parts by weight or more, small pinholes are easily generated on the surface of the coating film during the drying process of the coated product. The generation mechanism of these small pinholes is unknown, but it is considered that the BHT sublimated by heating comes out from the surface of the coating film which is being cured.

If necessary, a colorant, an organic or inorganic filler, a foam stabilizer such as organic silicone, and an internal release agent such as zinc stearate may be used as other auxiliary agents.

As the modified MDI composition, a reaction product of diphenylmethane diisocyanate (hereinafter abbreviated as MDI) and a polyhydric alcohol, a reaction product of MDI in the presence of a catalyst or under heating, or a mixture thereof is used. Degeneration
The ratio of isocyanate groups in the MDI composition to active hydrogen-containing groups in the active hydrogen-containing composition is in the range 0.8 to 1.5.

From these active hydrogen-containing compositions and modified MDI compositions, RIM
Polyurethane molded using a high-pressure foaming machine for polyurethane / Polyurethane coated with urethane-based paint on a polyurea molded product /
The polyurea molded product coated product can be put into a drying chamber at 80 to 120 ° C. and dried to be used as an automobile number, a wind gasket and the like. As the urethane-based paint, a well-known one-part or two-part non-yellowing solution type paint is used.

If necessary, a primer may be applied before the urethane paint is applied to the molded product.

[Examples and Comparative Examples]

Active hydrogen-containing composition A (1) Polyether polyol having a terminal primary degree of conversion of 95% and a molecular weight of 6000, which is obtained by adding ethylene oxide and propylene oxide to glycerin 79 parts by weight (2) 1-methyl-3,5-diethyl- Mixture of 2,4-diaminobenzene and 1-methyl-3,5-diethyl-2,6-diaminobenzene 21 parts by weight (3) DABCO 33LV (33% dipropylene glycol solution of triethylenediamine) 0.1 parts by weight (4) A uniform mixture of dibutyltin dilaurate 0.
1 part by weight Modified MDI composition B Urethane modified 4.4'-MDI (isocyanate content 23%)
54 parts by weight Urethane-based paint C Flexen 101 (manufactured by Nippon Paint Co., Ltd.) (One-component paint) Examples and Comparative Examples Using a high-pressure foaming machine for RIM, active hydrogen-containing composition A and modified M
A stabilizer was added as shown in Tables 1 and 2 to a total of 100 parts by weight of the DI composition B, and the modified MDI composition B was added so that the isocyanate index was 107 while stirring under pressure to dissolve air. The mixture was mixed and poured into an automobile bumper-shaped mold heated to 70 ° C. After 30 seconds, the mold was opened and the molded bumper was taken out. Urethane paint C was applied to this bumper with a spray gun. 20 in a drying room at 120 ° C
Dry for minutes. Then, it was placed in a 90 ° C. ventilated oven for heating and taken out 40 days later. Using a SM color computer (manufactured by Suga Test Instruments Co., Ltd.), the color difference value ΔE of the coating film surface after heating was measured based on the color tone before heating.

The results are shown in Tables 1 and 2.

[Effects of the Invention] The coated surface of a polyurethane / polyurea molded article obtained by using an aromatic polyamine as a chain extender is likely to be discolored by sunlight or heat. As shown in Examples and Comparative Examples, hindered phenolic stabilizers were molded into molded products.
By using 0.1 to 1.0 parts by weight per 100 parts by weight, it is possible to obtain a coated polyurethane / polyurea molded product with less discoloration of the coated surface and a smooth coating surface.

Claims (3)

[Claims] 1. A polyether polyol having (a) a molecular weight of 1800 to 12000 and a terminal primary rate of 90% or more, or a mixture thereof (b) an aromatic polyamine and (c) a catalyst, a foaming agent, and a molded article 100. 0.1 to 1.
Urethane for polyurethane / polyurea moldings produced by reaction injection molding from an active hydrogen-containing composition consisting of 0 part by weight of a hindered phenolic stabilizer, and optionally other auxiliaries, and a modified diphenylmethane diisocyanate composition. Polyurethane / polyurea molded product coated with a base paint 2. A polyurethane according to claim 1, characterized in that the hindered phenolic stabilizer is 2,6-di-tert-butyl-4-methylphenol.
Polyurea molded product Painted product 3. The aromatic polyamine is 1-methyl-3,5-diethyl-2,4-diaminobenzene and / or 1-methyl-3,5-diethyl-2,6-diaminobenzene. A coated article of the polyurethane / polyurea molded product according to claim 1 or 2.