JPH0354966B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a thermoplastic polyurethane that has excellent hydrolysis resistance and heat resistance, good low-temperature properties, and has no tendency to crystallize. Conventionally, polyurethane has been produced by reacting high-molecular polyols such as polyester polyols and polyether polyols with polyisocyanates and, if necessary, low-molecular compounds with active hydrogen atoms. Products using polyester polyol as a material have poor hydrolysis resistance, and as a result, the surface becomes sticky in a relatively short period of time.
Otherwise, cracks may occur, which greatly limits the use of the material. 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. In addition, when a polycarbonate polyol with good hydrolysis resistance, such as 1,6-hexanediol polycarbonate, is used as the polymer polyol component,
Although the above-mentioned drawbacks that occur when polyether polyols are used are improved, 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 that in the molecule as a high-molecular polyol,

[Formula] A polymeric diol having a group, such as poly(β-methyl-
It was discovered that polyurethane using diol (δ-valerolactone) has extremely excellent hydrolysis resistance and also has light resistance, cold resistance, etc.
-134100 and Japanese Patent Application No. 1983-230396). However, subsequent research revealed that this

Polyurethane using a polymer polyol having a [formula] group has poor heat resistance, and if left under high temperatures, the polyurethane will undergo thermal decomposition, resulting in loss of the excellent performance of the polyurethane. I found it. The purpose of the present invention is to

[Formula] A thermoplastic polyurethane with significantly improved heat resistance without substantially impairing the excellent hydrolysis resistance, light resistance, cold resistance, etc. of polyurethane using a polymer polyol having a group. Our goal is to provide the following. As a result of research to achieve this purpose, the inventors of the present invention found that

[Formula] Polymer diols having a group have low heat resistance, but after reacting the terminal hydroxyl group of the polymer diol with isocyanate, the heat resistance is significantly improved, and the average molecular weight of the polymer diol is reduced to 2200 or less. It was discovered that even more heat resistance could be obtained by
The invention has been completed. That is, in producing thermoplastic polyurethane from a polymeric diol, an organic diisocyanate, and a chain extender, the present invention ()

[Formula] Using a polymeric diol with an average molecular weight of 800 to 2200, the polymeric diol () is completely reacted with an excess of organic diisocyanate at a temperature below 120°C, and then a chain extender is added to conduct melt polymerization. Alternatively, the polyurethane can be produced by solid-phase polymerization, or by mixing a polymeric diol, an organic diisocyanate, and a chain extender at a temperature of 120° C. or lower, and then solid-phase polymerizing the mixture. Of course, even in this method of proceeding with polymerization in a solid phase, it is more preferable to carry out the solid phase reaction at 120°C or lower. If the polymerization is carried out at a temperature of 120°C or lower, polyurethane can be obtained while suppressing depolymerization of the polymer diol into monomers during polymerization, but the molecular weight of the polymer diol is defined by the present invention. If this range is exceeded, when this thermoplastic polyurethane is melt-molded by extrusion molding, injection molding, etc. (these moldings are usually carried out under high-temperature conditions of 200°C or higher), severe depolymerization into monomers will occur. The odor of the monomer is strong, and the resulting polyurethane is plastic-like, hard and brittle. In the case of conventionally commonly used polyurethane, polyurethane elastomer molded products with elasticity can be obtained by extrusion molding, injection molding, etc. without major deterioration, regardless of the average molecular weight of the polymer diol. Considering the fact that

The fact that in the case of polymeric diols having a [Formula] group, significant deterioration occurs when the average molecular weight exceeds 2200 can be said to be a completely unique phenomenon. Particularly in the present invention, it is preferable that the average molecular weight of the polymeric diol is 1800 or less. The molecular weight of the polymeric diol is preferably smaller from the viewpoint of the heat resistance of the polyurethane, but from the viewpoint of the low-temperature properties of the polyurethane, a molecular weight of 800 or more is preferable. In the molecule used in the present invention

[Formula] The polymer diol having an average molecular weight of 800 to 2,200 is specifically poly(β-methyl-δ-valerolactone) diol or a polymer diol mixture containing this, or β-methyl-δ- It is a block or random copolymerized polymeric diol with an average molecular weight of 800 to 2200 obtained by ring-opening copolymerization with valerolactone as one component. Poly(β-methyl-δ-valerolactone) diol is obtained by ring-opening polymerization of β-methyl-δ-valerolactone using a low molecular weight compound having two active hydrogen atoms as an initiator. Examples of the above-mentioned low molecular weight compounds having two active hydrogen atoms include ethylene glycol, butanediol,
Examples include low molecular diols such as -methyl-1,5-pentanediol, low molecular diamines such as ethylenediamine and hexamethylene diamine, and low molecular alkanolamines such as ethanolamine. Poly(ε-caprolactone) diol obtained by the same method as above and polyester diol obtained by condensation polymerization of diol and dicarboxylic acid generally have a high melting point of 30 to 60°C and a strong tendency to crystallize. Polyurethanes obtained from molecular diols tend to lose their elasticity due to crystal hardening of the soft segment components, and these polymer diols have high melt viscosity, which can impede workability when synthesizing polyurethane. , the poly(β-methyl-δ-valerolactone) skeleton itself is amorphous, and therefore the polymeric diol used in the present invention becomes a liquid with extremely low viscosity at room temperature and has the above-mentioned drawbacks. Not yet. Methyl-δ-valerolactone includes α-methyl-δ-valerolactone, β-methyl-δ-valerolactone, γ-methyl-δ-valerolactone, and δ-methyl-δ-valerolactone.
Only poly(β-methyl-δ-valerolactone)-based polyurethanes are superior in hydrolysis resistance. Polyurethanes containing other methyl-δ-valerolactones or ring-opened polymers from non-methyl-substituted δ-valerolactones as soft segment components do not have satisfactory hydrolysis resistance, as do other polyester polyurethanes. .
Furthermore, poly(ε-caprolactone) polyurethane is also unsatisfactory in terms of hydrolysis resistance. Furthermore, poly(methyl-δ-valerolactone)
Among polyurethanes based on polyurethanes, only poly(β-methyl-δ-valerolactone) polyurethanes are particularly excellent in terms of light resistance. Furthermore, wear resistance, oil resistance,
In terms of cold resistance and other mechanical properties, it is completely comparable to conventionally known polyester polyurethanes. In the present invention, favorable results are obtained in terms of hydrolysis resistance when poly(β-methyl-δ-valerolactone) diol accounts for 20% by weight or more, particularly 40% by weight or more of the total polymeric diol, and In other words, when the total amount of polymeric diol is poly(β
-methyl-δ-valerolactone) diol provides the best hydrolysis resistance. Furthermore, another effect can be obtained by replacing 20% by weight, especially 40% by weight or more of polyethylene adipate diol, polyhexamethylene adipate diol, etc., which tend to crystallize, with poly(β-methyl-δ-valerolactone) diol. Since polyurethane has hydrolysis resistance and is also suppressed from crystallization, it has good low-temperature characteristics 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.

Using a polymeric diol into which a group [Formula] has been introduced provides even better results in terms of heat resistance. Especially β-methyl-δ-
After ring-opening polymerization of valerolactone using a low-molecular-weight compound with two active hydrogen atoms as an initiator, further ε-
Average molecular weight 800 to 2200, especially average molecular weight 800 to 2200, obtained by adding caprolactone and reacting
1800 polymer diol is particularly preferred in terms of heat resistance. In this case as well, from the viewpoint of hydrolysis resistance, the group formed by ring opening of β-methyl-δ-valerolactone, i.e.

It is preferable that the proportion of the group [Formula] is 20% by weight or more, particularly 40% by weight of the total polymeric diol. Most preferably, −(
In addition to excluding the group based on the low molecular compound used as the ring-opening polymerization initiator for CO・CH ₂・_{CH 2 ・}CH ₂・CH 2 ・CH ₂・O)- _o H and β-methyl-δ-valerolactone. is everything

[Formula] is a group. Examples of the organic diisocyanate used in the present invention include diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6
- Aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate , 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated phenylene diisocyanate, and other aliphatic or alicyclic diisocyanates. Organic diisocyanates may be used alone or in combination. Furthermore, in the synthesis of polyurethane, low molecular weight compounds having two active hydrogen atoms are usually used as chain extenders, and these low molecular weight compounds having active hydrogen atoms are also used in the method of the present invention. Typical examples of these low molecular weight compounds having active hydrogen atoms include ethylene glycol, butanediol, propylene glycol,
1,6-hexanediol, 1,4-bis(β-
diols such as hydroxyethoxy)benzene, 1,4-cyclohexanediol, bis(β-hydroxyethyl)terephthalate, xylylene glycol, water, hydrazine, and diaminodiphenylmethane, diaminodiphenyl ether, 3,3'- Examples include diamines such as dichloro-4,4'-diaminodiphenylmethane and phenylenediamine, and these may be used alone or in combination. Regarding the operating method for obtaining polyurethane according to the present invention, the reaction of poly(β-methyl-δ-valerolactone) diol with a molecular weight of 2200 or less and an excess organic diisocyanate is completed in advance at a temperature of 120°C or lower, preferably 100°C or lower. After the prepolymer of terminal isocyanate is synthesized, a chain extender is added thereto, vigorously stirred and mixed, and the molten mixture is poured onto a plate or vat and heated at a temperature of, for example, 50°C to 160°C. by a method of reacting at a temperature followed by pulverization, or by melt polymerizing the above-mentioned molten mixture in a kneader such as a kneader with a powerful stirrer, or by continuous melt polymerization using a multi-screw extruder; A method is adopted in which a polymeric diol, an organic diisocyanate, and a chain extender are mixed at a temperature of 120° C. or lower, the reaction product becomes a solid state, and then pulverized using a kneader or the like and then polymerized in a solid state. By these methods, the thermoplastic polyurethane elastomer targeted by the present invention can be obtained. Next, the uses of the polyurethane obtained in the present invention include hoses, tubes, belts, films, coatings, sporting goods, automobile parts, shoes, rolls, gears, leather, etc. Next, the present invention will be explained in more detail with reference to Examples. In the examples, the hydrolysis resistance of polyurethane is determined by subjecting a 60 μm polyurethane film to a hydrolysis acceleration test in hot water at 100°C for one week, then redissolving the film in DMF, and measuring the retention of logarithmic viscosity. The rate was also evaluated. For evaluation of heat resistance, use Rigaku's differential scanning calorimeter TG-DSC.
This was carried out by measuring the thermogravimetric loss rate after 5 hours at a constant temperature of 220° C. using 10 mg of the sample in nitrogen. The raw materials used in the present invention are shown with abbreviations, and the relationship between the abbreviations and the compounds is as follows.

【table】

[Table] Examples 1 to 6, Comparative Examples 1 to 6 Polymer diols of various molecular weights and MDI and BD
were mixed in a kneader at a temperature of 60°C based on the composition shown in Table 1, and polymerization was carried out. At this time, as the polymerization progresses, it becomes solid, but if it is further mixed in a kneader, the solid will be pulverized. Thereafter, the reaction proceeded in powder form at a temperature of 100°C to obtain a high molecular weight polyurethane powder.

[Table] This polyurethane was dissolved in DMF to make a 60μ film and subjected to hydrolysis resistance test and heat resistance test.

【table】

[Table] Example 7 1500 g (1 mol) of poly(β-methyl-δ-valerolactone) diol (molecular weight 1500)
After reacting 1000 g (4 moles) of MDI at 80°C for 1 hour in a nitrogen stream, the amount of remaining isocyanate was determined to be the theoretical remaining amount by a conventional method for quantifying the remaining isocyanate, and P-β-MVL was substantially reduced. I confirmed that everything was responding. After that, BD270g (3
After adding mol) and vigorous stirring, the molten mixture was cast onto an aluminum vat.
Then, the mixture was heated to 140-150°C for 2 hours to complete the polymerization. The polyurethane obtained according to this method is
It has no monomer odor, has good elasticity, and is TG-
Thermal analysis by DSC (220°C for 5 hours) also showed that the weight loss rate was as small as 6%, and the thermal stability was good. Example 8 P-β-MVL (molecular weight 1300) 1300g (1 mol)
After reacting 750 g (3 mol) of MDI and MDI in a nitrogen stream at 80°C for 1 hour, the remaining isocyanate amount was determined to be the theoretical remaining amount and P-β-MVL was found to be substantially I confirmed that everything was responding. This prepolymer and 180 g (2 moles) of BD were charged into a twin-screw continuous extruder using a metering pump, and melt polymerization was carried out at 200°C.
The resulting polymer melt was pelletized using a pelletizer. The polyurethane obtained according to this method has no monomer odor, has good elasticity,
Thermal analysis by TG-DSC (220°C, 5 hours) also showed that the weight loss rate was as small as 7%, and the thermal stability was good.

Claims (1)

[Claims] 1. In producing thermoplastic polyurethane from a polymer diol, an organic diisocyanate, and a chain extender, () a polymer diol having an average molecular weight of 800 to 2,200 and having a [formula] group in the molecule as a polymer diol; () The polymeric diol is completely reacted with an excess of organic diisocyanate at a temperature below 120°C, and then a chain extender is added, and the polymeric diol and organic diisocyanate are combined by melt polymerization or solid phase polymerization. 1. A method for producing thermoplastic polyurethane, comprising: mixing an extender at a temperature of 120°C or lower, and then producing polyurethane by solid phase polymerization.