JPH0469187B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing stabilized polyurethane moldings. More specifically, when producing a polyurethane molded product from a polyol and an isocyanate, the present invention provides (a) general formula [1] [In the formula, R ₁ represents a lower alkyl group. ] Hindered phenol represented by (b) general formula [2] [In the formula, R ₂ represents hydrogen or an alkyl group having 1 to 4 carbon atoms. R ₃ represents an alkyl group having 1 to 12 carbon atoms. n represents 1 or 2. ]
This is a method for producing a polyurethane molded article, which is characterized in that the hindered amine represented by the above formula is combined with (c) an organic phosphorus or sulfur antioxidant. Although polyurethane is recognized as an elastic polymer with excellent chemical resistance, abrasion resistance, toughness, durability, and cold resistance, it can deteriorate due to various factors such as light, heat, water, and oxygen. Various stabilizers have been added because of the disadvantages of In recent years, in particular, it has become possible to reduce minute damage to automobile parts, improve safety, reduce weight, increase freedom in design, and improve corrosion resistance. bumper,
Large amounts of polyurethane are used in exterior parts such as side moldings, front grilles, and spoilers.
In such applications, since they are used under harsh conditions due to outdoor exposure, there is a strong demand for improved weather resistance and heat resistance. By the way, polyurethane exterior parts like this used to be mostly unpainted products colored black, but recently, due to user preference and design freedom, parts can be partially painted in various colors after the parts are manufactured. Things are being demanded. However, conventional products had problems such as the stabilizer spraying out onto the painted surface during painting, and the paint film discoloring after painting, resulting in loss of commercial value. Furthermore, the weather resistance and heat resistance of the unpainted parts of conventional products were never sufficient. For these reasons, there has been a strong desire for a polyurethane molded product that has good weather resistance and heat resistance in unpainted areas and has excellent coating performance. As a result of intensive research on this point, the present inventors found that (a) a hindered phenol represented by the general formula [1], (b) a hindered amine represented by the general formula [2], and (c) an organic phosphorus or sulfur-based We discovered that by combining antioxidants, it is possible to obtain polyurethane molded products with excellent weather resistance, heat resistance, and paintability that would have been unimaginable with each component alone.
We have arrived at the present invention. Examples of the hindered phenol represented by the general formula [1] used in the present invention include, for example, 2-
(2-hydroxy-3-t-butyl-5-methylbenzyl)-4-methyl-6-t-butylphenyl acrylate, 2-(2-hydroxy-3
-t-butyl-5-ethylbenzyl)-4-ethyl-6-t-butylphenyl acrylate and the like. The amount of these additives to be added is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the polyurethane molded product. Examples of hindered amines represented by general formula [2] include bis(2,2,6,6-tetramethyl-4-piperidine) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc. It is. The amount of these additives to be added is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the polyurethane molded product. Examples of organic phosphorus or sulfur-based antioxidants include triphenyl phosphite, triotadecyl phosphite, tris-(nonylphenyl)-phosphite, diphenyl-isodecyl phosphite,
4,4'-butylidene-bis(3-methyl-6-t
-butylphenyl-di-tridecyl) phosphite, cyclic neopentanetetriyl bis(octadecyl phosphite), phenyl-diisodecyl phosphite, dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, etc. It is. The amount of these additions is 100% of the polyurethane molding.
0.01 to 2 parts by weight, preferably 0.02 parts by weight
~1 part by weight. The polyurethane in the present invention is a two-component polyurethane elastomer made by reacting a polyol and an isocyanate, and the polyol is preferably a polyester polyol or polyether polyol having an average molecular weight of 1000 to 8000 and having two or more hydroxyl groups per molecule, or It is a mixture of these. The isocyanate is preferably a polyisocyanate such as toluene diisocyanate or diphenylmethane diisocyanate, or a mixture or modified version thereof. In the present invention, catalysts, blowing agents,
There is no problem in containing various additives such as chain extenders, colorants, inorganic fillers, violet light absorbers, and antioxidants. Coloring agents used in this case include inorganic pigments such as titanium oxide, iron oxide, and carbon black, organic pigments or dyes such as azo, phthalocyanine, quinacridone, and anthraquinone, and others that can generally be used to color polyurethane. Any known colorant can be used. Specifically, the method of the present invention can be carried out, for example, as follows. A polyol, a catalyst, a chain extender, a blowing agent, a colorant, a hindered phenol represented by the general formula [1] of the present invention, a hindered amine represented by the general formula [2], and an organic phosphorus or sulfur antioxidant (a ), (b) and (c) are mixed and diffused in advance, and the obtained polyol component and isocyanate are injected into a mold,
React and mold. At this time, the stabilizer as claimed in the claims used in the present invention may be blended into the isocyanate. Alternatively, if a polyurethane prepolymer is used, it may be added to this. Alternatively, the stabilizer described in the claims used in the present invention may be added to the colorant and used. According to the method of the present invention, a small amount of a hindered phenol represented by the general formula [1], a hindered amine represented by the general formula [2], and an organic phosphorus or sulfur antioxidant are added in the process of manufacturing a polyurethane molded product. As a result, it is possible to obtain a polyurethane molded product with extremely excellent weather resistance and heat resistance that could not have been expected with conventional methods alone, and even when this molded product is painted, there is no negative effect on the coating film.
It also has excellent coating performance. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited only to these Examples. In the Examples, all parts are by weight. Example 1 100 parts of polyether polyol (OH value 50, average molecular weight approximately 5000), 18 parts of 1,4-butadiol,
0.02 part of dibutyltin laurate, 0.45 part of triethylenediamine, 1 part of carbon black, 2-(2-hydroxy-3-t) as the stabilizer (a) of the present invention.
-butyl-5-methylbenzyl)-4-methyl-
1 part of 6-t-butylphenyl acrylate, (b) bis(2,2,6,6-tetramethyl-4-
0.5 part of (piperidine) sebacate and 0.3 part of diphenyl-isodecyl phosphorite (c) were kneaded in a three-roll mill. The obtained polyol component and 110 parts of modified diphenylmethane diisocyanate (NCO26%) were injected into a 50°C mold pre-coated with a wax-based mold release agent using a Henetske reaction injection molding machine at a discharge pressure of 145 kg/ ^cm3. After 2 minutes, it was taken out to produce a 4 mm thick black polyurethane sheet. Wipe off the mold release agent from this black polyurethane sheet with trichlorethylene, etc., and spray white melamine-modified urethane paint evenly with a spray gun to a thickness of about 40μ, leave it for 30 minutes, and then put it in a hot air dryer at 120℃ for 60 minutes. Baked. Next, using the unpainted black sheet and the white painted sheet, the temperature of the black panel of a sunshine-type weather meter based on JIS-A1415 was 83℃±3.
The changes in appearance were evaluated after 400 hours of irradiation at ℃. The results are shown in Table 1, and an extremely excellent stabilizing effect was obtained, with almost no discoloration of the coating film. Example 2 In Example 1, as the stabilizer (a) of the present invention, 2
1 part of -(2-hydroxy-3-t-butyl-5-methylbenzyl)-4-methyl-6-t-butylphenyl acrylate, (b) bis(2,
tris-2,6,6-tetramethyl-4-piperidine) sebacate and 0.3 part of diphenyl-isodecyl phosphorite as (c).
A black polyurethane sheet was produced by repeating the same operations as in Example 1, except that 0.3 parts of (nonylphenyl) phosphorite was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 1, and an extremely excellent stabilizing effect was obtained, with almost no discoloration of the coating film. Example 3 100 parts of polyether polyol (OH value 30, average molecular weight approximately 6000), 18 parts of 1,4-butanediol,
0.02 parts of dibutyltin laurate, 0.45 parts of triethylenediamine, 2 parts of iron oxide, 2-(2-hydroxy-3-t-butyl-5 as the stabilizer (a) of the present invention)
-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, 0.5 part of bis(2,2,6,6-tetramethyl-4-piperidine) sebacate as (b) and trifle as (c). 0.3 part of enilphosphite was kneaded in a three-roll mill. The obtained polyol component and 100 parts of modified diphenylmethane diisocyanate (NCO26%) were injected into a 50°C mold pre-coated with a wax-based mold release agent using a Henetske reaction injection molding machine at a discharge pressure of 140 kg/ ^cm3 . After 2 minutes, the sheet was taken out to produce a 4 mm thick brown polyurethane sheet, and the same evaluation as in Example 1 was performed. The results are shown in Table 1, and an extremely excellent stabilizing effect was obtained, with almost no discoloration of the coating film. Example 4 In Example 1, 2-
1 part of (2-hydroxy-3-t-butyl-5-methylbenzyl)-4-methyl-6-t-butylphenyl acrylate, (b) bis(2,2,
Same as Example 1 except that 0.5 part of 6,6-tetramethyl-4-piperidine) sebacate and 0.3 part of distearyl thiodipropionate were used instead of 0.3 part of diphenyl-isodecyl phosphite as (c). A black polyurethane sheet was manufactured by repeating the above operations, and the same evaluation as in Example 1 was performed. The results are shown in Table 1, and an extremely excellent stabilizing effect was obtained, with almost no discoloration of the coating film. Comparative Examples 1 to 5 In Example 1, 2-
Only 1.8 parts of (2-hydroxy-3-t-butyl-5-methylbenzyl)-4-methyl-6-t-butyl-phenyl acrylate (Comparative Example 1) was used as the stabilizer (b) of the present invention. Only 1.8 parts of (2,2,6,6-tetramethyl-4-piperidine) sebacate (Comparative Example 2), only 1.8 parts of diphenyl-isodecyl phosphorite as the stabilizer (c) of the present invention (Comparative Example 3), A black polyurethane sheet was produced by repeating the same procedure as in Example 1, except that only 1.8 parts of distearyl thiodipropionate (Comparative Example 4) was used as the stabilizer (c) of the present invention. A similar evaluation was made. The results are shown in Table 1, and were significantly inferior to those of the present invention.

【table】

[Table] In the case of a white painted sheet, the color difference (△E) was measured using a Hunter color difference meter in comparison with an unirradiated sheet.

Claims (1)

[Claims] 1. When producing a polyurethane molded product from a polyol and an isocyanate, (a) general formula [1] [In the formula, R ₁ represents a lower alkyl group. ] Hindered phenol represented by (b) general formula [2] [In the formula, R ₂ represents hydrogen or an alkyl group having 1 to 4 carbon atoms. R ₃ represents an alkyl group having 1 to 12 carbon atoms. n represents 1 or 2. ] The hindered amine represented by (c) and the organic phosphorus or sulfur antioxidant include triphenyl phosphite, triotadecyl phosphite, tris-(nonylphenyl)-phosphite, diphenyl-isodecyl phosphite,
4,4'-butylidene-bis(3-methyl-6-t
-butylphenyl-di-tridecyl) phosphite, cyclic neopentanetetriyl bis(octadecyl phosphite), phenyl-diisodecyl phosphite, dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate. A method for producing a polyurethane molded article, characterized by combining and blending one or more selected from among them.