JPH0262570B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyurethane that has excellent hydrolysis resistance and does not have a tendency to crystallize. Conventionally, polyurethane has been produced by reacting polyols such as polyester polyols and polyether polyols with polyisocyanates and, if necessary, low-molecular compounds containing active hydrogen atoms. Products using polyols have poor hydrolysis resistance, and as a result, the surface becomes sticky or cracks occur in a relatively short period of time, resulting in considerable limitations in use. Polyurethane using polyether polyol instead of polyester polyol has satisfactory hydrolysis resistance, but on the other hand, it has very poor light resistance and has poor mechanical properties, abrasion resistance, oil and solvent resistance. This will also cause difficulties in terms of sexuality. Furthermore, when a polycarbonate polyol with good hydrolysis resistance, such as 1,6-hexanediol polycarbonate, is used as the polyol component, the above-mentioned drawbacks that occur when a polyether polyol is used are improved, but Polycarbonate polyols are extremely expensive and still have poor cold resistance. On the other hand, conventional polyester polyurethanes with relatively good hydrolysis resistance include those using polycaprolactone polyol, and polyester polyurethanes obtained from 1,6-hexanediol, neopentyl glycol, and adipic acid. However, these polyurethanes do not have satisfactory hydrolysis resistance. The present inventors have discovered a method that is inexpensive, has excellent hydrolysis resistance and light resistance, and has excellent mechanical properties, oil resistance, abrasion resistance,
As a result of conducting research to obtain polyurethane that has all the characteristics of cold resistance, we found that as a polyol component,

It has been found that the above object can be achieved by using a polyol having an average molecular weight of 300 to 10,000 having the formula: within the molecule

[Formula] A polyol having an average molecular weight of 300 to 10,000 is specifically a poly(β-methyl-δ-valerolactone) polyol or a polyol mixture containing this, or a polyol containing β-methyl-δ-valerolactone. It is a block or random copolymerized polyol having an average molecular weight of 300 to 10,000 obtained by ring-opening copolymerization as a component. Poly(β-methyl-δ-valerolactone) polyol is obtained by ring-opening polymerization of β-methyl-δ-valerolactone with a low-molecular polyhydric alcohol such as ethylene glycol or butanediol. Poly(ε-caprolactone) polyols obtained by similar methods and polyester polyols obtained by condensation polymerization of diols and dicarboxylic acids generally have a high melting point of 30 to 60°C and a strong tendency to crystallize. Polyurethanes obtained from polyols tend to suffer from crystal hardening of the soft segment components, resulting in loss of elasticity.Furthermore, these polyols have high melt viscosity, which can impede workability when synthesizing polyurethane. methyl-δ-valerolactone)
Polyols are themselves amorphous polymers;
Moreover, since it is a liquid with extremely low viscosity at room temperature, it does not have the above-mentioned drawbacks. Methyl-δ-valerolactone includes α-methyl-δ-valerolactone, β-methyl-δ-valerolactone, and γ-methyl-δ-valerolactone, but the release of β-methyl-δ-valerolactone Only polyurethanes containing ring polymers or ring-opened copolymers as soft segment components have excellent hydrolysis resistance. Polyurethanes containing ring-opened polymers or ring-opened copolymers from other methyl-δ-valerolactones or non-methyl-substituted δ-valerolactones as soft segment components are resistant to hydrolysis, as are other polyester polyurethanes. Sexually unsatisfying. Similarly, only polyurethanes containing ring-opened polymers or ring-opened copolymers of β-methyl-δ-valerolactone as a soft segment component are particularly excellent in terms of light resistance. Furthermore, in terms of abrasion resistance, oil resistance, cold resistance, and other mechanical properties, it is comparable to conventionally known polyester polyurethanes. In the present invention, poly(β-methyl-δ-valerolactone) polyol is 20% of the polyols.
Favorable results are obtained in terms of hydrolysis resistance when the amount is at least 40% by weight, and when used alone, that is, when the total amount of polyol is at least 40% by weight, poly(β
-methyl-δ-valerolactone) polyol provides the best hydrolysis resistance. Furthermore, another effect can be obtained by replacing 20% by weight or more, especially 40% by weight or more of polyethylene adipate polyol or polyhexamethylene adipate polyol, which has a large crystallization tendency, with poly(β-methyl-δ-valerolactone) polyol. Polyurethane has excellent hydrolysis resistance and is also inhibited from crystallization, so it has good low-temperature properties and elastic properties. Furthermore, copolymers with other lactones, such as ε-
Randomly or blockally within the molecule obtained by ring-opening copolymerization of caprolactone and β-methyl-δ-valerolactone.

[Formula] Even when using a polyol into which a group has been introduced or when using a block polymer polyol made from an adipate polyester polyol and β-methyl-δ-valerolactone, the polyol component has a
% by weight, especially more than 40% by weight

[Formula] When it has a group, the same effect as described above can be obtained. In the present invention, the average molecular weight of the polyol is
It is usually in the range of 300 to 10,000, preferably in the range of 700 to 6,000. Also,

Examples of polyols that can be used in combination with the polyol having the formula group include all those commonly used in the production of polyurethane. Examples of the organic polyisocyanate include diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, phenylene diisocyanate, and 1,5-tolylene diisocyanate.
- Aromatic diisocyanates such as naphthylene diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, toluylene diisocyanate,
Examples include aliphatic or alicyclic diisocyanates such as hexamethyl diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. Polyisocyanates may be used alone or in combination. Furthermore, in the synthesis of polyurethane, low-molecular compounds having two or more active hydrogen atoms are usually used as chain extenders, and the method of the present invention also uses these low-molecular compounds having two or more active hydrogen atoms. can be used. Representative examples of these low molecular weight compounds having two or more active hydrogen atoms include ethylene glycol, butanediol, propylene glycol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1 , 4-cyclohexanediol, bis(β-hydroxyethyl) terephthalate, xylylene glycol and other diols,
Examples include water, hydrazine, ethylene diamine, propylene diamine, xylylene diamine, isophorone diamine, piperazine, phenylene diamine, tolylene diamine, adipic acid dihydrazide, isophthalic acid dihydrazide, etc., and these compounds may be used alone or in combination. It may also be used. Furthermore, if necessary, a monohydric low-molecular alcohol, a low-molecular amine, or the like may be used as a modifying agent. As for the operating method for obtaining polyurethane, known urethanization reaction techniques are used.
For example, by mixing a polyol and a low-molecular compound having two or more active hydrogen atoms,
After preheating to , add polyisocyanate compounds in an amount such that the ratio of the number of active hydrogen atoms to the number of NCO groups in these compounds is approximately 1:1, stir vigorously for a short time, and then leave at approximately 50 to 150 °C. Polyurethane is then obtained. Further, these reactions can also be carried out via a urethane prepolymer in order to reduce deviations in the reaction amount ratio. Polyisocyanate compounds are usually used in a very slight excess because they are affected by moisture and other factors. These reactions can also be carried out in a solvent consisting of one or more of dimethylformamide, diethylformamide, dimethylsulfoxide, dimethylacetamide, tetrahydrofuran, isopropanol, benzene, toluene, ethyl cellosolve, trichlene, and the like. In this case, it is advantageous to carry out the reaction at a concentration within the range of 10 to 40% by weight in order to obtain polyurethanes of high molecular weight. The polyurethane obtained by the method of the present invention has outstanding hydrolysis resistance, and therefore, this polyurethane can be used for sheets, films, belts, rolls, gears, vibration-proofing materials, cushioning materials, packing materials, shoes, Artificial leather, cushion materials, mechanical parts,
It is useful for elastic fibers and various other fields. The present invention will be specifically explained using Examples above.
In the examples, the hydrolysis resistance of polyurethane was evaluated by a young angle test. In the Youngle test, a 50μ thick polyurethane film was left at 70°C and 95% relative humidity for 28 days, and the tensile strength retention of the film before and after the Youngle test was evaluated.
Light resistance was also expressed by the tensile strength retention rate after 50 hours of exposure (carbon arc lamp) in an atmosphere of 63°C using a Sunshine Weather-Ometer (film thickness 50μ). Solvent resistance was determined by making a polyurethane film into a 200 μm thick film, and immersing the film in toluene and ethyl acetate at 30° C. for a day and night, and then expressing the degree of weight swelling. The cold resistance was evaluated by measuring the glass transition temperature (Tg) using a direct reading dynamic viscoelasticity meter Vibron Model DDV- (110HZ) manufactured by Toyo Sokki Co., Ltd. Abrasion resistance was measured using a Taber type abrasion tester (H-
22, the amount of wear (mg) at a load of 1000g and 1000 times) is also expressed. Further, the polyols, polyisocyanates, and chain extenders that are raw materials for polyurethane used in the examples are shown using abbreviations, and the relationship between the abbreviations and the compounds is as follows.

[Table] Examples 1 to 4, Comparative Examples 1 to 4 Polyurethane was produced using the raw materials shown in Table 1. That is, predetermined amounts of polyol and polyisocyanate were reacted at 60° C. under nitrogen. The obtained prepolymer was dissolved in dimethylformamide (hereinafter referred to as
It was dissolved in DMF (abbreviated as DMF) to a concentration of 25% by weight. Next, a predetermined amount of chain extender was dissolved in DMF, and this solution was added to the above-mentioned prepolymer solution and reacted by stirring at 70° C. for 10 hours to obtain a DMF solution of polyurethane. After adjusting the polyurethane concentration of this solution to 10% by weight, this solution was cast onto a glass plate and dried to obtain dry coatings with thicknesses of 50μ and 200μ. This dry film was subjected to various physical property tests. The results are shown in Table 2.

【table】

【table】

[Table] Comparative Examples 5 to 7 A polyurethane dry film was obtained in the same manner as in Example 1 except that the compounds shown in Table 3 were used as the polyol component in Example 1, and the hydrolysis resistance and The low temperature characteristics were investigated. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1. A polyurethane characterized by using a polyol having an average molecular weight of 300 to 10,000 and having a [Formula] group in the molecule as a polyol component when producing polyurethane by reacting a polyol and a polyisocyanate. Manufacturing method.