JPH0248008B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyurethane polymer having excellent elastic recovery properties, especially elastic recovery properties at low temperatures. In recent years, thermoplastic segmented polyurethane polymers with a two-phase microstructure of a soft domain consisting of flexible so-called soft segments and a hard domain consisting of rigid paracrystalline so-called hard segments aggregated by hydrogen bonding have been developed. It has attracted attention because it can impart properties suitable for the final purpose by changing its concentration, size, size distribution, etc., and has been developed in various ways. Hard segments usually consist of aromatic or aliphatic diisocyanates bonded to short-chain diols or short-chain diamines, while soft segments include polyoxyalkylene glycols, condensed polyester glycols, lactone polyester glycols, polycarbonate diols, etc. used. Among these soft segment components, polyoxyalkylene glycol is preferred for its low-temperature properties and hydrolysis resistance, polyoxytetramethylene glycol is preferred for its excellent mechanical properties and moisture absorption resistance, and polyurethane polymer as fibers, artificial leather, thermoplastic urethane resin,
Used for cast elastomers. It is true that among polyoxyalkylene glycols, polyoxytetramethylene glycol imparts excellent properties to polyurethane polymers as mentioned above, but due to the crystallization tendency of polyoxytetramethylene glycol, it has elastic properties that function as a soft segment. In particular, low-temperature properties such as elastic recovery at low temperatures are not necessarily satisfied, and it is currently desired to improve elastic recovery even at room temperature. The present inventors have conducted intensive research to solve these problems, and have found that when a specific polyalkylene ether diol having a side chain methyl group is used as a soft segment component, excellent low-temperature properties and elastic recovery properties can be obtained. The present invention was achieved by discovering that a polyurethane polymer having the following properties can be obtained. That is, the present invention provides a method for producing a polyurethane polymer from an organic polyfunctional isocyanate and a polyoxyalkylene glycol in the presence or absence of two or more active hydrogen-containing compounds of low molecular weight. The purpose of the present invention is to produce a polyurethane polymer characterized in that at least 10% by weight of the polyalkylene ether diol represented by the following formula (2) is used. HO−(A-O−) _n −(B−O−) _o H () (However, if the repeating unit is

[Formula] −(CH ₂ −CH ₂ −CH ₂ −CH ₂ −O−), and A is

[Formula] B is -CH ₂ -CH ₂ -CH ₂ -CH ₂ -, m and n are positive values satisfying m+n=6 to 140 and m/n=10/90 to 100/0 (molar ratio). (number) Next, the present invention will be explained in detail. The organic polyfunctional isocyanate used in the present invention is not particularly limited, and any organic diisocyanate or organic triisocyanate that is normally used to obtain a polyurethane polymer can be used. That is, the aromatic diisocyanates include 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, 4,
4'-diphenylmethane diisocyanate, 1,5
- Naphthalene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, tolidine isocyanate, etc. are used. Further, if some degree of crosslinking is required, a small amount of organic triisocyanate such as triphenylmethane triisocyanate or tris(isocyanate phenyl) thiophosphate may be used in combination. As the aliphatic diisocyanate, 1,6-hexamethylene diisocyanate,
1,10-decamethylene diisocyanate, isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, etc. are used. Examples of low molecular weight compounds having two or more active hydrogens include water, ethylenediamine, propylene diamine, phenylene diamine, diphenylmethane diamine, and bifunctional low molecular weight compounds.
Aliphatic or aromatic diamines such as xylene diamine, diols such as ethylene glycol, propylene glycol, butylene glycol, and other ethanolamine hydrazine can be used. These compounds are usually used as chain extenders, and some If cross-linking is required, trifunctional materials such as trimethylolpropane, glycerin, or N,N,N',N'-tetrakis (2-
Tetrafunctional compounds such as (hydroxypropyl) ethylenediamine are used in small amounts as crosslinking agents. Polyoxyalkylene glycols include polyethylene glycol, poly(1,2 and 1,3
-propylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, and random or block copolymer glycols obtained from ethylene oxide and propylene oxide or ethylene oxide and tetrahydrofuran. Further, at least 10% by weight, preferably 20% by weight or more of this polyoxyalkylene glycol is a specific polyalkylene ether diol having a side chain methyl group and represented by the above formula (). This particular polyalkylene ether diol can be easily obtained by cationic ring-opening polymerization or cationic ring-opening polymerization of 3-methyloxetane or 3-methyloxetane and tetrahydrofuran, and details regarding its production can be found in Japanese Patent Application No. 57-8610 and This is stated in the specifications of Japanese Patent Application No. 57-8611. That is, it can be obtained by adding perchloric acid and acetic anhydride or perchloric acid and fuming sulfuric acid to a mixed system of 3-methyloxetane or 3-methyloxetane and tetrahydrofuran, or using a super strong acid such as fluorosulfonic acid as a polymerization initiator. The reaction product is saponified to obtain a terminal diol. In the case of a copolymer of 3-methyloxetane and tetrahydrofuran, the 2-methyl-1,3-propylene units and 1,4-tetramethylene units may be distributed randomly or in blocks, and the state of these distributions depends on the copolymerization method and conditions. However, the sum of m and n shown in formula () is approximately 6.
up to 140, preferably between about 9 and 100, and the m/n ratio is 10/90 to 100/0 (molar ratio)
must be satisfied. If the sum of m and n is less than 6, the molecular weight as a soft segment component will be too small and the function of the soft domain will be insufficient, and if it is larger than 140, the handling properties and reactivity during polyurethane production, especially the tendency for phase separation, will deteriorate. It is not desirable in terms of appearance etc. Also, the m/n ratio is good when m is large and approaches 100, that is, a homopolymer of 3-methyloxetane, but it is 10/n.
If the proportion of 3-methyloxetane units in the copolymer is less than 90, that is, less than 10 mol%, the distribution of side chain methyl groups becomes too small, and crystallinity of the polyoxytetramethylene block based on tetrahydrofuran appears, which is the objective. This is not preferable because the low-temperature properties and elastic recovery functions are impaired. For the same reason, the polyalkylene ether diol according to the present invention can be used in combination with other polyalkylene glycols such as polytetramethylene glycol, but the polyalkylene ether diol according to the present invention (formula ()) is at least 10% by weight. It should preferably be used in an amount of 20% by weight or more.
The polyalkylene glycol that can be used in combination is not particularly limited, but polyethylene glycol, polypropylene glycol, random or block copolymers obtained from ethylene oxide and propylene oxide or ethylene oxide and tetrahydrofuran are undesirable because they have too high hydrophilicity, and Poly-1,2 containing alcohol
-Propylene glycol is not preferred because of its low reactivity in polyurethanization. In general, polytetramethylene glycol gives good results because it is easily available on the market. Next is the polyurethanization reaction, which involves the so-called one-shot method in which the reaction components are reacted all at once, or the polyalkylene ether diol of the present invention or a mixture with other polyoxyalkylene glycols to first produce a prepolymer with isocyanate ends and chain extension. A so-called prepolymer method can be used in which low-molecular diols, diamines, etc. are reacted as agents, and anisole, chlorobenzene, o-dichlorobenzene,
The reaction may be carried out in a solution state using a solvent such as -methylpentanone-2, dimethylformamide, or N,N-dimethylacetamide. Furthermore, in order to promote the reaction between the active hydrogen compound and the isocyanate group, tertiary amines such as triethylamine, dimethylethanolamine, 1,8-diazabicyclo[5.4.0]-7-undecene, morpholine derivatives, or dibutyltin are added. Dilaurylate, stannous 2-ethylcaproate, dibutyltin-
Organometallic compounds such as di(2-ethylhexoate) can be used as catalysts. Next, the content of the present invention will be specifically explained with reference to Examples. Note that the hydroxyl values shown in the Examples are values measured by the phthalic anhydride-pyridine method, and the acid values are also values obtained by the direct neutralization titration method of a pyridine solution. Tensile strength and elongation properties are determined from a press sheet with a thickness of approximately 1 mm.
Punch out JIS-compliant dumbbell-shaped test pieces, 23℃, 65
The humidity was adjusted for 10 days or more under %RH conditions and then measured using a Tensilon universal tensile tester at a crosshead speed of 50 mm/min. Tensile strength at break, tensile elongation at break,
The tensile yield strength, 100% modulus, and 300% modulus are values determined from the obtained stress-strain curve.
In addition, the instantaneous elastic recovery rate and the delayed elastic recovery rate are determined by attaching a marked line at a distance a to the dumbbell-shaped test piece.
Stretch it to 200% and hold it in this stretched state for 5 minutes, then remove the stress and make it into a free state, then immediately measure the distance between the gauge lines b, and then measure the distance between the gauge lines c again 10 minutes after the stress has been removed. It was measured and calculated from the following formula. Instantaneous elastic recovery rate = 2a-b/a x 100% Delayed elastic recovery rate = 2a-c/a x 100% Example 1 First, a method for producing polyether diol used in the present invention will be described. 6.8 ml of acetic anhydride was added to 100 ml of anhydrous 3-methyloxetane obtained by adding metallic sodium to 3-methyloxetane, which had been dehydrated and dried overnight after adding fresh caustic potash pellets, and then distilled after reflux dehydration. It was cooled to -70°C using cryogen. 2.8 ml of 70% perchloric acid was added dropwise to this system over about 20 minutes with vigorous stirring. After the dropwise addition was completed, stirring was continued for about 1 hour at -70°C, and then the temperature was gradually raised to room temperature over about 1 hour. During this time, the reaction was conducted under a dry nitrogen atmosphere to avoid contact with the atmosphere to prevent moisture absorption. Seal the post-reaction system at room temperature.
It was left for 50 hours. The reaction system became a colorless and transparent viscous liquid. Add about 100ml of pure water to stop the reaction,
The mixture was heated to about 90° C. for about 1 hour while stirring to remove unreacted monomers. After removing the aqueous layer, 200 ml of 1/2N caustic potassium ethanol solution was added, and the mixture was heated and stirred at about 90°C for 2 hours to effect saponification. Ethanol was distilled off, ether was added to make an ether solution, activated carbon and activated clay were added, and the mixture was left to stand for several hours. After the solid content was separated and the ether was distilled off, about 67 g (yield 79.5%) of poly(oxy-2-methylpropylene) glycol was obtained in the form of a colorless and transparent viscous liquid. This product has a hydroxyl value of 100.9mgKOH/g and an acid value of 1.2mg.
KOH/g, number average molecular weight determined from hydroxyl value
It was 1112. Next, polyurethanization was attempted using the obtained poly(oxy-2-methylpropylene) glycol. That is, 20.0 g (0.0180 mol) of poly(oxy-2-methylpropylene) glycol is
Using a ml flask, the mixture was first heated to 100° C. with stirring, and then dehydrated and dried for 1 hour under reduced pressure to about 2 mmHg. The contents were returned to normal pressure with dry nitrogen, and after the temperature had fallen to room temperature, 50 ml of N,N-dimethylacetamide was added and dissolved with stirring. Add 9.0 g (0.0360 mol) of diphenylmethane diisocyanate to this solution.
was dissolved in 50 ml of N,N-dimethylacetamide (partially suspended), and then 1,8
0.05 ml of a 4% N,N-dimethylacetamide solution of -diazabicyclo[5.4.0]-7-undecene (hereinafter abbreviated as DBU) was added and stirred at room temperature for 3 hours. 1.08g of ethylenediamine in this solution
(0.0180 mol) in N,N-dimethylacetamide
A solution dissolved in 25 ml was added dropwise over about 20 minutes, and the reaction was further continued at room temperature for 2 hours. Polyurethane was obtained by adding the reaction product to a large amount of pure water to precipitate the polymer, washing it alternately with water and methanol, and drying it in a vacuum dryer at 60°C for about 10 hours. This polyurethane was dissolved again in N,N-dimethylacetamide, adjusted to a concentration of 10%, and then casted into a glass plate with a silicone mold release agent baked on.
After air drying, water washing, and drying, casting was repeated to produce a film with a predetermined thickness. Comparative Example 1 20 g (0.0199 mol) of poly(oxytetramethylene) glycol with a number average molecular weight of 1003, 9.98 g (0.0399 mol) of diphenylmethane diisocyanate,
A polyurethane film was prepared in the same manner as in Example 1 from 1.20 g (0.0199 mol) of ethylenediamine. The performance of the polyurethane films obtained in Example 1 and Comparative Example 1 will be compared and shown below.

[Table] Example 1 is superior to Comparative Example 1 in instantaneous and delayed elastic recovery rates at room temperature and bending recovery rate at low temperatures. Example 2 24.5 g of 3-methyloxetane-tetrahydrofuran (20:80 weight ratio) copolymerized diol with a hydroxyl value of 67.8 and a number average molecular weight of 1656 determined from the hydroxyl value
(0.0148 mol) to 1.8 g of 1,4-butanediol
(0.0200 mol) was added and stirred at about 3 mmHg and 130° C. for 1 hour to simultaneously dry and mix. Continued
While stirring at 130° C., 18 g (0.0348 mol) of diphenylmethane diisocyanate was added in powder form little by little to the reaction system over about 1 hour. After stirring was continued for an additional 4 hours, no increase in the viscosity of the system was observed, so the reaction product was taken out, allowed to cool to room temperature, and then a 1 mm thick press sheet was prepared. Comparative Example 2 24.5 g (0.0163 mol) of polyoxytetramethylene glycol with a number average molecular weight of 1500, 1.7 g (0.0189 mol) of 1,4-butanediol, and 8.8 g (0.0352 mol) of diphenylmethane diisocyanate.
Polyurethane was obtained in the same manner as in Example 2. The physical property values of the polyurethanes obtained in Example 2 and Comparative Example 2 are shown below.

[Table] Example 3 2.13 g (0.00127 mol) of poly(oxy-2-methyl-1,3-propylene) glycol with a number average molecular weight of 1682 determined from the hydroxyl value and poly(oxy-2-methyl-1,3-propylene) glycol with a number average molecular weight of 1003 determined from the hydroxyl value in the same manner. Oxytetramethylene glycol 7.87g (0.00785mol) 3
Drying and mixing were performed for 1 hour under stirring at 120° C. and mmHg. Add 20 ml of N,N-dimethylacetamide to make a solution Diphenylmethane diisocyanate 4.56
A solution (partial suspension) prepared by adding 40 ml of N,N-dimethylacetamide to G. g (0.01822 mol) was added to the glycol solution. Next, 4%N of DBU,
0.05 ml of N-dimethylacetamide solution was added as a catalyst, and the reaction was carried out at room temperature for about 3 hours. N,N- in which 1.24 g (0.0911 mol) of p-xylene diamine was dissolved in the thus obtained prepolymer solution.
Dimethylacetamide solution was added to the system in about 20 minutes. The reaction was further carried out at room temperature for about 3 hours, and the reaction solution was poured into a large amount of pure water to precipitate the polymer.
As in Example 1, a 1 mm thick sheet was prepared by washing and drying using the solution casting method, and its physical properties were evaluated. Tensile strength at break 255Kgf/ ^cm2 Tensile elongation at break 890% 100% modulus 80Kgf/ ^cm2 300% modulus 152Kgf/ ^cm2 Instant elastic recovery rate 82.0% Delayed elastic recovery rate 95.0%

Claims (1)

[Claims] 1. In producing a polyurethane polymer from an organic polyfunctional isocyanate and a polyoxyalkylene glycol in the presence or absence of two or more active hydrogen-containing compounds of low molecular weight, the polyoxyalkylene glycol A method for producing a polyurethane polymer, characterized in that at least 10% by weight of the alkylene glycol is a polyalkylene ether diol represented by the following formula (). HO-(A-O-) _n -(B-O-) _o H () (However, the repeating unit is [Formula]-[CH ₂ -CH ₂ -CH ₂ -CH ₂ -O-], and A is [formula] B is −CH ₂ −CH ₂ −CH ₂ −CH ₂ −, m and n are m+n=6 to 140,
m/n = 10/90 to 100/0 (a positive number that satisfies the molar ratio)