JPH0116248B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyurethane with excellent elastic recovery properties and a method for producing the same. Conventionally, polyurethanes having a linear structure, long-chain polyols having hydroxyl groups at both ends, organic diisocyanates, and diols and diamines called chain extenders having two relatively low molecular weight active hydrogens,
It is synthesized by reacting with alkanolamine, etc., and polyester polyols and polyether polyols are mainly used as long chain polyols having hydroxyl groups at both ends. Therefore, polyester polyols include ethylene glycol, 1,4-butylene glycol, 1,6
- Polyester polyols synthesized from hexane glycol etc. and adipic acid, and polycaprolactone polyols made from ε-caprolactone are commonly used. As the polyether polyol, a polymer or copolymer of ethylene oxide or propylene oxide, and polytetramethylene glycol, which is a polymer of tetrahydrofuran, is used. Among these, polyether polyols, especially polytetramethylene glycol, not only have excellent water resistance, but also polyurethanes made from these polyols have excellent elastic recovery properties. It is widely used in fields such as urethane elastomers that require small physical properties. However, polyether polyols are susceptible to oxidative deterioration due to their ether bonds, and have the disadvantage of extremely poor weather resistance and heat resistance. On the other hand, polyurethane using ethylene glycol adipate polyester, which is a polyester polyol, has excellent elastic recovery properties, but has the disadvantage of poor water resistance and the product becomes unusable within one to two years. Although 1,4-butylene glycol adipate polyester has a certain degree of water resistance, the elastic recovery properties of its urethane are extremely poor. Furthermore, polyurethane made from polycaprolactone polyol made from ε-caprolactone has not only excellent water resistance but also excellent weather resistance and heat resistance, which are disadvantages of polyether polyols. However, despite these characteristics, it has a serious drawback of very poor elastic recovery, so it could not be used in fields such as spandex. The inventors of the present invention have conducted intensive studies to solve the defects of polycaprolactone-based urethanes, and have found that polyurethanes made from polycaprolactone polyester diol synthesized from neopentyl glycol, dibasic acid, ε-caprolactone, or oxycaproic acid. It was discovered that this material exhibits excellent elastic recovery properties not seen in conventional products, leading to the present invention. That is, in producing polyurethane by reacting an organic diisocyanate with a compound having two or more active hydrogens in the molecule, the present invention uses neopentyl glycol, a dibasic acid, an ester thereof, or an ester thereof as the compound having active hydrogen. Its anhydride, ε
- The elastic recovery rate obtained using a polycaprolactone polyester polyol consisting of caprolactone or oxycaproic acid with an average molecular weight of 500 to 5000 and an ε-caprolactone (or oxycaproic acid) content of 40 to 95% by weight is preferably 50% or more. provides a polyurethane having an excellent elastic recovery of 70% or more and a method for producing the same. The average molecular weight in the present invention is a value determined by the following formula by measuring the hydroxyl value of polycaprolactone polyester polyol. Average molecular weight = 56.11 x N x 1000 / hydroxyl value Hydroxyl value: Value measured according to 6.4 of JIS K-1557 N: Number of hydroxyl groups in one molecule of polycaprolactone polyester polyol In addition, the elastic recovery rate in the present invention is as follows. It was calculated using the formula. That is, it is the recovery rate (at 20° C.) after stretching polyurethane by 300% and releasing the tension, and then leaving it for 10 minutes, and is expressed by the following formula. Recovery rate = (1-l'-l/l) x 100 (%) l: Length between the gauge lines before stretching l': Length between the gauge lines after stretching and releasing tension In the present invention, In particular, as a dihydric alcohol,
Neopentyl glycol is used, especially as a dibasic acid, its ester or its anhydride.
Preferably, adipic acid, sebacic acid or an ester thereof is used. As the third raw material, ε-caprolactone, one that is industrially produced by oxidizing cyclohexanone with a peracid such as hydrogen peroxide or peracetic acid by Bayer-Villiger reaction can be used. Further, other cyclic lactones or oxyacids other than ε-caprolactone or oxycaproic acid, such as trimethylcaprolactone and valerolactone, can also be used in combination with ε-caprolactone, as long as they do not impair the characteristics of the present invention. Polycaprolactone polyester polyol synthesized from polyhydric alcohol, polybasic acid, ε-caprolactone or oxycaproic acid has an average molecular weight of 500 to 5000 and a hydroxyl value of 14 to 140 KOHmg/g, preferably 40 to 5000.
100KOHmg/g, the content of ε-caprolactone or oxycaproic acid is 40-95% by weight, preferably 60
-95% by weight, more preferably 65-90% by weight. Polycaprolactone polyester polyol can be synthesized by mixing and heating neopentyl glycol, a dibasic acid, ε-caprolactone, or oxycaproic acid, and performing a dehydration esterification reaction, a ring opening reaction, and a transesterification reaction. Alternatively, a polyester polyol synthesized by a dehydration esterification reaction of neopentyl glycol and a dibasic acid is mixed with a polycaprolactone polyol synthesized by ring-opening reaction of ε-caprolactone with a polyhydric alcohol, and then the two are transesterified. The desired product can also be obtained by reaction. Alternatively, it can be synthesized by ring-opening polymerization of ε-caprolactone to a polyester polyol having a small molecular weight. These reactions are carried out at 130-240°C, preferably 140-240°C.
Perform at 230℃. If the temperature exceeds 250°C, not only the resin will be colored, but also a depolymerization reaction of caprolactone will occur, making it impossible to obtain the desired product. This reaction uses 0.05 to 1000 ppm of catalyst, preferably 0.1 to 100 ppm. As the catalyst, organic titanium compounds such as tetrabutyl titanate and tetrapropyl titanate, and tin compounds such as dibutyltin laurate, tin octylate, dibutyltin oxide, stannous chloride, stannous bromide, and stannous iodide may be used. Can be done. It is preferable to carry out the reaction while passing an inert gas such as nitrogen from the viewpoint of preventing coloring of the resin. The organic diisocyanates used in the production of the polyurethane of the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Examples include 4,4'-diphenylmethane diisocyanate, toridine diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, and 1,5-naphthalene diisocyanate. Examples of low molecular weight compounds having active hydrogen called chain extenders used in the practice of the present invention include ethylene glycol, propylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, Pentanediol, 1,6-hexanediol, ethylenediamine, propylenediamine, hydrazine, isophoronediamine, metaphenylenediamine, 4,4'-
Diaminodiphenylmethane, diaminodiphenyl sulfone, 3,3'-dichloro-4,4'-diaminodiphenylmethane, etc. can be used. The method for producing polyurethane in the present invention is to react a polyol with an excess organic diisocyanate to produce a prepolymer having terminal isocyanate groups, and then react with a chain extender such as a diol or diamine to produce a prepolymer that is made into a polyurethane. Any method can be employed, such as a method or a one-shot method in which polyurethane is produced by adding all the components at the same time. These polyurethanes can be produced without a solvent or in a solvent. As the solvent, one that is inert to isocyanate is used. For example, toluene, xylene, ethyl acetate, butyl acetate,
Methyl ethyl ketone, dimethylformamide, tetrahydrofuran, etc. are used. The polycaprolactone polyester polyol urethane of the present invention not only has excellent water resistance, weather resistance, and heat resistance, but also has an excellent elastic recovery rate compared to conventional products. This is because polyester chains, such as adipate polyester, are partially inserted into the polycaprolactone polyol molecule, which causes polycaprolactone to exhibit some crystallinity. This can be explained by the fact that the structure of the crystalline crosslinking point becomes stronger.
This effect is particularly pronounced when neopentyl glycol is used to form polyester chains. The polyurethane of the present invention is very advantageously used in spandex, thermoplastic urethane elastomers, thermosetting urethane elastomers, hard and soft urethane foams, adhesives, artificial leathers, synthetic leathers, paints, and the like. Next, the present invention will be explained with reference to Examples and Comparative Examples, but the present invention is not limited by these. Example Chubu means parts by weight. Synthesis Example 1 3540 parts of adipic acid and neopentyl glycol were placed in a 4-necked flask equipped with a nitrogen inlet tube, thermometer, condenser for removing ester-formed water, and stirring device.
3466 parts and 0.053 parts of tetrabutyl titanate were charged, and the dehydration and esterification reaction was carried out at 140°C to 220°C for 27 hours, resulting in an acid value of 0.54KOHmg/g and a hydroxyl value.
A polyester polyol of 159.4 KOHmg/g (units will be omitted below) was obtained. 3364 parts of this polyester polyol, 6236 parts of ε-caprolactone, and tetrabutyl titanate.
A polycaprolactone polyester polyol having a hydroxyl value of 55.4, an acid value of 0.3, and a melting point of 4 to 5°C was obtained by adding 0.063 parts and heating and stirring at 190°C for 15 hours to perform a ring-opening reaction and a transesterification reaction of the lactone. The lactone content was 65.0% by weight. Synthesis Example 2 2369 parts of polyester polyol from adipic acid and neopentyl glycol obtained in Synthesis Example 1, 116.2 parts of ethylene glycol, ε-caprolactone
A polycaprolactone polyester polyol having a hydroxyl value of 56.3, an acid value of 0.6, and a melting point of 14 to 15°C was obtained by mixing 7918 parts of tetrabutyl titanate and 0.08 parts of tetrabutyl titanate and heating and stirring at 220°C for 8 hours. The lactone content was 76.1% by weight. Synthesis Example 3 695 parts of polyester polyol from adipic acid and neopentyl glycol obtained in Synthesis Example 1, 103 parts of ethylene glycol, ε-caprolactone
By mixing 4,503 parts of tetrabutyl titanate and 0.053 parts of tetrabutyl titanate and heating and stirring at 200°C for 12 hours, a polycaprolactone polyester polyol having a hydroxyl value of 55.2, an acid value of 0.34, and a melting point of 38 to 41°C was obtained. The lactone content was 85.0% by weight. Synthesis Example 4 Commercially available 1,4-butylene glycol adipate (trade name Nitsuporan N-4010, hydroxyl value 56.1KOH
mg/g) 280 parts to 65.1 parts of ethylene glycol, ε
- 1938.0 parts of caprolactone and 0.024 parts of tetrabutyl titanate were mixed and reacted at 220°C for 8 hours to obtain polycaprolactone polyester diol by transesterification of polycaprolactone and 1,4-butylene adipate. Hydroxyl value is 54.5, acid value
It was 0.07. The lactone content was 85%. Synthesis Comparative Example 1 Ethylene glycol was added to the same equipment as Synthesis Example 1.
632 parts of ε-caprolactone, 19,380 parts of ε-caprolactone, and 0.2 parts of tetrabutyl titanate were charged and reacted at 170°C for 5 hours to obtain polycaprolactone diol having a hydroxyl value of 56.2 and an acid value of 0.25. Examples 1, 2, 3, 4 and Comparative Example 1 Each polyol obtained in Synthesis Examples 1, 2, 3, 4 and Comparative Synthesis Example 1 was treated with 4,4'-diphenylmethane diisocyanate (MDI) for chain extension. Agent 1,
A polyurethane resin was obtained by reacting 4-butylene glycol. The results are shown in Table 1. The composition is
NCO/OH=1.05, chain extender/polyol=2.0.

Table 1 shows that the polyurethane of the present invention has excellent elastic recovery properties. It was mentioned above that the polyurethane of the present invention has excellent elastic recovery properties and is therefore useful as an elastic yarn, and this application will be described in detail below. When used as an elastic yarn, the following range is particularly practical. That is, when producing elastic threads from polyurethane obtained by reacting an organic diisocyanate with a compound having two or more active hydrogens in the molecule, the active hydrogen-containing compounds include dihydric alcohols, dibasic acids, its ester or its anhydride, ε
- consists of caprolactone or (and) oxycaproic acid, and has a hydroxyl value of 35 to 150 KOHmg/g, preferably 40 to 100 KOHmg/g, more preferably 40
~60KOHmg/g, ε-caprolactone and oxycaproic acid content 60-95, preferably 65-90
This method uses polycaprolactone polyester diol in an amount of % by weight, and has particularly excellent elastic recovery properties, as well as excellent heat resistance and alkali resistance. As the dihydric alcohol, neopentyl glycol, 1,4-butylene glycol, and 1,6-hexanediol are particularly preferred. The dibasic acid is preferably adipic acid, sebacic acid or an ester thereof. When a titanium compound is selected as a catalyst, a yarn with better elastic recovery can be provided. In particular, to describe the range of excellent elastic yarns, the polycaprolactone polyester diol of the present invention obtained by the above-mentioned synthesis reaction has 2
It does not have a complete block copolymer structure consisting of a polycaprolactone chain and a polyester chain, in which caprolactone is ring-opened and polymerized at the end of a polyester diol consisting of a hydrolic alcohol and a dibasic acid. The polycaprolactone polymer contains a random copolymer structure in which dihydric alcohol and dibasic acid residues are randomly distributed through transesterification. This means that when a block copolymer obtained by ring-opening ε-caprolactone in a polyester diol consisting of a dihydric alcohol and a dibasic acid is further heated, its melting point and melt viscosity gradually decrease until they reach a constant value. I can prove it. That is, the block copolymer changes into a random copolymer structure through the transesterification reaction, and the crystallinity of the copolymer decreases. The polycaprolactone polyester diol as described above may be spun by a conventional method. In addition, as stabilizers for polyurethane elastic threads, usual antioxidants, ultraviolet absorbers, antifungal agents, heat deterioration stabilizers, hydrolysis inhibitors, etc., as well as fillers such as titanium oxide, pigments, etc. should be added. Can be done. Particularly effective as a hydrolysis inhibitor is the addition of carbodiimide compounds such as Stavaxol I, P (trade name of Bayer AG). A linear polyurethane elastic polymer synthesized by a conventional method can be spun by any of the wet method, dry method, and melt method. The polycaprolactone polyester diol-based urethane elastic yarn of the present invention not only has excellent water resistance, weather resistance, and heat resistance, but also has a higher elastic recovery rate than conventional products. This is because dihydric alcohol residues and dibasic acid residues, which are components of polyester chains such as adipate polyester, are partially inserted at random into the polycaprolactone diol molecule, which reduces the crystallinity of polycaprolactone. This can be explained by the fact that the structure of the crystalline crosslinking point, which is a repeating portion of the chain extender and diisocyanate of the polyurethane, becomes stronger. The polyurethane elastic yarn of the present invention can be used alone or mixed with other fibers for clothing, and can be used in a wide range of applications such as foundations such as socks, women's underwear such as bras and panties, and even industrial elastic fabrics. . Next, an application example of spinning according to the present invention will be shown. Application Examples 1 to 3 and Application Comparative Examples 1 and 2 Polycaprolactone polyester diol obtained in Synthesis Examples 1, 3, and 4, polycaprolactone diol of Synthesis Comparative Example 1, and Synthesis Comparative Example 2 described below
A polyurethane elastomer was obtained by subjecting polyethylene adipate diol to a urethane reaction with 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butylene glycol as a chain extender at 135°C. These are isocyanate group/hydroxyl group =
1.05 (equivalent ratio), chain extender/long chain diol = 1.19
(molar ratio). The polyurethane elastomer thus obtained was melt-spun using an extruder. The spinning temperature was adjusted in the range of 180 to 220°C so that the elongation of the yarn was 400%.
Furthermore, the ratio of extrusion speed and take-up speed was adjusted to obtain a urethane elastic yarn of 14,000 denier that had been stretched five times.
The physical properties, heat resistance, and alkali resistance of these elastic yarns were measured and shown in Tables 2 and 3. The lactone content of the products obtained in Synthesis Example 1, Synthesis Example 3, and Synthesis Example 4 is
They were 65.0%, 85.0%, and 85.0%. Synthesis Comparative Example 2 Ethylene glycol was added to the same equipment as Synthesis Example 1.
750 parts of adipic acid, 1537 parts of adipic acid, and 0.023 parts of tetrabutyl titanate, and a dehydration esterification reaction was carried out at 170°C for 30 hours to obtain a polyester diol having an acid value of 0.70 and a hydroxyl value of 53.4.

【table】

[Table] The evaluation method used in the above application example is explained. Note (A) Stress retention rate at 100% elongation This is the stress retention rate when a test piece is held at 100% elongation for 10 minutes, and is expressed by the following formula. Stress retention rate at 100% elongation = Stress after 10 minutes of 100% elongation / Stress immediately after 100% elongation x 100 (%)
Note (B) Long-term elongation strain at 200% elongation at 20°C. After holding the test piece at 20°C for 24 hours at 200% elongation, the tension was released and the strain was measured after a certain period of time. 24-10' is the strain when 10 minutes have passed after releasing the tension, and 24-24 is the strain when 24 hours have passed after releasing the tension, which is expressed by the following equation. 200% elongation at 20℃ long-term elongation strain = l' - l/l x 100 (%) l: Length between the marked lines before elongation l': Between the marked lines after a certain period of time after elongation and tension release Length Note (C) Repeated extension strain The strain was measured 10 minutes after the tension was released after 20 repeated extensions at maximum extension, and is expressed by the following formula. Cyclic elongation strain = l″-l/l×100 (%) l: Length between gauge lines before elongation l″: After 20 repeated elongations, release the tension and
Length between marked lines after minutes Note (D) Creep A load is applied to the test piece so that the stress becomes 1 g/1000 d, and the temperature is measured when the elongation increases by 40% as the temperature increases. Note (E) Cutting temperature: Apply a load to the test piece so that the stress becomes 1 g/1000 d, raise the temperature (at an arbitrary speed), and measure the temperature when the test piece cuts. Note (F) Elongation at break and stress at extension Based on JIS K6301-1. Note (G) Alkali resistance Boil in 10% caustic soda aqueous solution for 3 hours. After that, the prescription for Note (A) increased by 200% to 100%.
Measure the % stress retention. Tables 2 and 3 show that the polyurethane elastic yarn of the present invention has excellent elastic recovery properties, as well as excellent heat resistance and alkali resistance.

Claims (1)

[Claims] 1. When producing polyurethane by reacting an organic diisocyanate with a compound having two or more active hydrogens in the molecule, the above-mentioned active hydrogen-containing compound is produced by a dehydration esterification reaction of neopentyl glycol and adipic acid. An average molecular weight of 500 obtained by the transesterification reaction of synthesized polyester polyol and ε-caprolactone.
5,000 and an ε-caprolactone content of 40 to 95% by weight.