JPH0421690B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyurethane molding composition, more specifically, a hexamethylene diisocyanate polymer having an isocyanurate ring as an organic polyisocyanate (hereinafter abbreviated as isocyanurated polyisocyanate), polyol 1, a chain extender, a blowing agent, The present invention relates to a polyurethane molding composition for molded articles having a high-density skin layer comprising a catalyst and a catalyst. In recent years, polyurethane molded products having a high-density skin layer have been used for automotive components such as steering wheels, instrument panels, armrests, headrests, bumpers, spoilers, etc., shoe soles, and housings for various devices. However, since aromatic polyisocyanates are usually used as polyisocyanates in these molded products, they have the disadvantage of yellowing when exposed to sunlight. For this reason, when producing colored products, it is limited to colors such as black or brown where discoloration is less noticeable, and if a light color is required, it is necessary to use pre-painting (in-mold coat) or post-painting to protect the paint film. Alternatively, a method of adding large amounts of antioxidants and ultraviolet absorbers has been adopted. However, although the paint film protection method is effective in preventing discoloration, there are difficulties in terms of process and work, and the additive method has limitations in preventing discoloration. Therefore, the main object of the present invention is to provide a polyurethane molding composition that has a high degree of stability against discoloration due to sunlight etc. even without a protective coating. Conventionally, hexamethylene diisocyanate (hereinafter referred to as
Polyurethane resins using HDI (abbreviated as HDI) are known to have excellent weather resistance, and are usually
It is provided as a polyol adduct or Biuretz modified product of HDI, and is mainly used in the fields of paints and adhesives. A method of using aliphatic or alicyclic polyisocyanates in molded products was published in Japanese Patent Publication No. 15599 (1983) and Japanese Patent Publication No. 15599 (1983).
28212, etc., but the method described here uses polyisocyanate as a monomer as it is, or uses a prepolymer containing a large amount of monomer. Polyurethane molded products are usually manufactured under conditions where the raw materials and molds are heated, so the use of monomers with high vapor pressure poses health and safety problems. Further, when HDI is used in the method described herein, it has drawbacks such as difficulty in achieving hardness due to its molecular structure and poor heat resistance. The present inventors focused on the excellent color fastness of HDI,
As a result of repeated research to improve the drawbacks of the HDI monomer, it was discovered that the isocyanurate form of HDI not only gives molded products appropriate hardness and excellent heat resistance, but also further improves discoloration resistance. This discovery led to the present invention. That is, the present invention provides a molding composition comprising an organic polyisocyanate, a polyol 1, a chain extender, a blowing agent, and a catalyst, in which the polyisocyanate comprises (A) a polyol 2 having a molecular weight of 62 to 3000 and a functional group number of 2 to 3; is an isocyanurated polyisocyanate obtained by reacting this with an excess amount of hexamethylene diisocyanate to obtain a hexamethylene diisocyanate adduct, which is then converted into an isocyanurate, and (B) the isocyanurated polyisocyanate is present in the molecule. A molded product having a high-density skin layer, characterized in that the molecule contains 10% by weight or more of a substance having one isocyanurate ring, and 90% by weight or less of a substance having two or more isocyanurate rings in the molecule. The present invention relates to a polyurethane molding composition for articles. In the present invention, the isocyanurated polyisocyanate is prepared by adding tertiary amines, alkyl-substituted ethyleneimines, tertiary alkyl phosphines, acetylacetone metal salts, metal salts of various organic acids, etc. alone to the HDI adduct as a catalyst, or It can be obtained by carrying out an isocyanurate reaction at 100°C or lower, using a cocatalyst as necessary. In this case, the HDI adduct is polyol 2 and
It is obtained by urethanizing this by a known method using an excess amount of HDI. As the polyol 2, a di- or tri-functional polyol having a molecular weight of 62 to 3,000 is suitable. For example, diols include ethylene glycol, diethylene glycol, 1,
3-butanediol (hereinafter abbreviated as 1,3-BG),
2 such as 1,4-butanediol, propylene glycol, dipropylene glycol (hereinafter abbreviated as DPG), neopentyl glycol, 1,6-hexane glycol (hereinafter abbreviated as 1,6-HG), etc.
Examples include alcohols, polyester polyols, and polyether polyols. Examples of triols include trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane, polyester polyols, and polyether polyols. As the polyol 2, these may be used alone or a mixture of two or more thereof in any proportion may be used. The reaction can proceed more easily by using a phenolic hydroxy compound, an alcoholic hydroxy compound, tertiary amines, or the like as a cocatalyst, if necessary. The isocyanurate reaction can be carried out either in the presence or absence of a solvent. The catalyst can be made inactive by using known strong acids such as phosphoric acid, sulfuric acid, etc. as terminators. It was found that by reacting a portion of HDI with a polyol and introducing a urethane bond, it became easier to convert it into an isocyanurate, and at the same time, the resulting polymer had further improved compatibility with other resins. The isocyanurate reaction solution from the HDI adduct contains unreacted HDI, and by removing them by distillation or extraction, a highly pure isocyanurate can be obtained. In the present invention, a compound having an isocyanurate group at the end obtained by forming an isocyanurate ring of HDI by the above-mentioned method and then reacting it with a polyol or water can also be used as the isocyanurated polyisocyanate component. . The HDI trimer forming the isocyanurate ring is
By liquid chromatography, HDI trimer has a molecular weight of around 504 (having one isocyanurate ring in one molecule) and can be quantified. In addition to HDI trimers that form isocyanurate rings, there are isocyanurates with a higher degree of polymerization (those having two or more isocyanurate rings in one molecule). Since the isocyanurate reaction by the method of the present application can be carried out at a low temperature and in a relatively short time, it is difficult to produce a polymer with a degree of polymerization higher than a certain degree, but the molecular weight of the trimer forming the isocyanurate ring can be reduced. The amount of polymeric isocyanurate can be reduced several times. Depending on the production method, a higher molecular weight isocyanurate may also be included. The isocyanurated polyisocyanate of the present invention consists of 10% by weight or more of polyisocyanates having one isocyanurate ring in the molecule and 90% by weight or less of polyisocyanurates having two or more isocyanurate rings in the molecule. In this case, if the content of the isocyanurate ring-forming trimer (having one isocyanurate ring in the molecule) is less than 10% by weight, the compatibility with polyol 1 etc. will decrease and the viscosity will decrease. It rises and becomes difficult to handle, and the tensile properties of the resulting molded product deteriorate. In addition, heat resistance and hardness are also reduced. In the present invention, the polyol 1 used together with the isocyanurated polyisocyanate to obtain the polyurethane molding composition is one having two or more hydroxyl groups in one molecule, and is conventionally used for producing polyurethane molded products. All items used can be used. Examples include polyether polyol, polyester polyol, polybutaene polyol, etc. Two or more of these polyols can be used in combination. Examples of polyether polyols include ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, sorbitol, sucrose, bisphenol A,
Water, one or more monomers such as ethylene oxide, propylene oxide, epichlorohydrin, etc. using as an initiator one or more compounds having at least two active hydrogen atoms such as ethylenediamine, tolylene diamine, diphenylmethanediamine, etc. is produced by addition polymerization using a known method. Examples of polyester polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-BG-, 1,4-butylene glycol,
Tetramethylene glycol, hexamethylene glycol, glycerin, trimethylolpropane,
One or more compounds having at least two or more hydroxyl groups, such as pentaerythritol and sorbitol, and malonic acid, maleic acid,
It can be produced by a known method using one or more compounds having at least two carboxyl groups, such as succinic acid, adipic acid, tartaric acid, sebacic acid, and terephthalic acid. Also included are polyester polyols such as those obtained by ring-opening polymerization of caprolactone. Examples of the chain extender used in the present invention include ethylene glycol, butylene glycol, diethylene glycol, DPG, tripropylene glycol, glycerin, trimethylolpropane, diethanolamine, triethanolamine, tolylene diamine, hexamethylene diamine, methylene bis-o- At least 2 such as chloraniline etc.
It is a low-molecular compound with active hydrogen groups. As the blowing agent used in the present invention, all those conventionally used in the production of polyurethane foam can be used. For example, water and/or halogen-substituted aliphatic hydrocarbon blowing agents. The amount of blowing agent to be used is appropriately determined depending on the purpose of use. The catalysts used in the present invention are all those used in polyurethane production. Examples include tertiary amines, diazabicycloalkenes and salts thereof, and organometallic compounds described in US Pat. No. 3,799,898 and Japanese Patent Publication No. 15599/1983. When obtaining a molded article using the composition of the present invention, various surfactants, coloring agents such as dyes and pigments, reinforcing materials and fillers such as mica and glass fibers, flame retardants, and oxidation inhibitors may be used as necessary. UV absorbers, other auxiliary agents, and additives can be used. The polyurethane moldings of the present invention having a high-density skin layer are produced by means such as casting or injection (RIM technology) to have an NCO index in the range of 70 to 140, preferably in the range of 90 to 120. in this case,
The reaction can be accelerated by heating the raw materials and the mold as necessary. Molded products obtained using the composition of the present invention have excellent weather resistance and discoloration resistance, so they can be colored in any desired color tone without additional treatment such as protection with a coating film, and are also coated with isocyanurate. Because it uses polyisocyanate, it has improved heat resistance and can be used in a wide range of applications such as handles, instrument panels, and shoe soles. The present invention will be further explained in detail with reference to Examples.
The present invention is not limited to this. In the examples, all parts and percentages are by weight unless otherwise specified. Preparation of organic polyisocyanate Preparation 1 Synthesis of isocyanurated polyisocyanate 500 ml equipped with thermometer, stirrer and nitrogen-sealed tube
Pour the specified amount into a four-neck flask made of laminated glass.
HDI, polyol, catalyst, and cocatalyst were charged in the proportions shown in Table 1, and the air in the flask was replaced with nitrogen.
The mixture was heated to the reaction temperature shown in Table 1 while stirring. The reaction was carried out at the same temperature for the predetermined time shown in Table 1, and the NCO content was measured, and the values shown in Table 1 were obtained. The reaction solution was a pale yellow transparent liquid. Phosphoric acid was added as a terminator to this reaction solution, and after stirring at the reaction temperature for 1 hour, free HDI was removed by distillation. The obtained liquid is a pale yellow transparent liquid.
The NCO content, free HDI, and trimer forming isocyanurate rings were measured and shown in Table 1. Preparation 2 Synthesis of HDI adduct (for comparative example) 500ml equipped with thermometer, stirrer, and nitrogen-sealed tube
Pour the specified amount into a four-neck flask made of laminated glass.
Add HDI and polyol in the proportions shown in Table 1, replace the air in the flask with nitrogen, and while stirring,
The mixture was heated to the reaction temperature of . The reaction was carried out at the same temperature for the predetermined time shown in Table 1, and the NCO content was measured, and the values shown in Table 1 were obtained. The reaction solution was a pale yellow transparent liquid. Free HDI was removed from this reaction solution by distillation. The resulting liquid was pale yellow and transparent, and its NCO content and free HDI were measured and shown in Table 1. Example 1, Comparative Examples 1 to 3 100 parts of polyether polyol (Poly G 845 manufactured by Asahi Glass), 10 parts of ethylene glycol, 5 parts of Freon-11, 1 TEDA L-33 (manufactured by Toyo Soda)
A premix consisting of 1 part dibutyl tin dilaure, 0.8 part Irganox 1010 (manufactured by Ciba Geigy) and the isocyanate shown in Table 1 were heated to 30°C and mixed in a ratio of NCO index 105 to form a composition for polyurethane molding. The resulting composition was poured into an open mold to allow free foaming, and then poured into a 5 mm x 120 mm x 420 mm mold heated to 55°C to obtain a molded product. Table 2 shows the foaming speed during free foaming and the physical properties of the molded product.

【table】

【table】

【table】

[Table] Comparative Example 4 100 parts of polyester polyol (N-155 manufactured by Nippon Polyurethane Industries), 1,4-butanediol
A premix consisting of 10 parts, 0.8 parts of water, 0.5 parts of TEDA L-33, 0.5 parts of dibutyltin dilaurate, and 0.4 parts of Sanol 144 (manufactured by Ciba Geigy) was prepared as shown in Table 1.
HDI adducts No. 1-2 were heated to 50°C,
They were mixed at a ratio of NCO index 98, and the foaming rate and physical properties of a molded product measuring 5 mm x 120 mm x 420 mm were as follows. Cream time (sec) 28 Rise time (sec) 165 Density (g/cm ³ ) 0.75 Hardness (C) 65 Elongation (%) 90 Tensile strength (Kg/cm ² ) 10.5 Weather resistance (Note 1) Appearance Cracking △E 3.5 (Note 1) Sunshine type weatherometer 400 hours

Claims (1)

[Scope of Claims] 1. A molding composition comprising an organic polyisocyanate, polyol 1, a chain extender, a blowing agent, and a catalyst, wherein (A) the organic polyisocyanate has a molecular weight of 62 to 3000 and a functional group number of 2 to 3; An isocyanurated polyisocyanate obtained by reacting polyol 2 with an excess amount of hexamethylene diisocyanate to obtain a hexamethylene diisocyanate adduct and converting this into an isocyanurate, (B) the isocyanurate polyisocyanate is A high-density skin layer characterized by having 10% by weight or more of one isocyanurate ring in the molecule and 90% by weight or less of having two or more isocyanurate rings in the molecule. A polyurethane molding composition for molded articles comprising: