JPH08100043A - Water-base polyurethane resin - Google Patents

Abstract

PURPOSE: To obtain a water-base polyurethane resin which is soft and elastic at low temps. by reacting a specific polyol, a hydrophilicity-donating substance having carboxyl and hydroxyl groups, and a polyisocyanate compd. CONSTITUTION: A random copolymer polyol comprising 5-30% units of formula I (wherein one of R1 and R2 is H and the other is methyl) and 95-70% units of formula II is reacted with a polyisocyanate compd. in an equivalent ratio of NCO group to OH group of 1.0-4.7 to give a urethane prepolymer having isocyanate groups at both molecular ends. The prepolymer is subjected to chain extension by the reaction with a hydrophilicity-donating substance having at least one carboxyl group and at least two hydroxyl groups, giving an isocyanate- terminated prepolymer having carboxyl groups in the molecule. The prepolymer is then neutralized by putting it into an aq. soln. of an alkali or alkaline earth metal salt or of an org. base and is dispersed stably in water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous polyurethane resin, and more particularly to a more flexible and elastic aqueous polyurethane resin in a low temperature region. In the present invention, aqueous is a general term for water dispersibility and water solubility.

[0002]

2. Description of the Related Art In recent years, from the viewpoints of pollution, environmental pollution, etc., there has been an increasing interest in water-based resins in place of conventional organic solvent-based resins. Among them, water-based polyurethane resins are artificial leathers because of their excellent mechanical properties. It is used in a wide range of fields as a textile treatment agent or adhesive. Conventionally, it is known that an aqueous polyurethane resin using polytetramethylene ether glycol as a polyol component has excellent rubber elasticity with relatively little temperature dependence and is also excellent in hydrolysis resistance.

[0003]

However, in the physical properties of the film of this resin as well, a decrease in elongation and an increase in stress were confirmed as the temperature decreased, and the flexibility was lost, resulting in a large change in the physical properties at low temperatures. It was often pointed out that improvement was requested.

[0004]

Means for Solving the Problems The present inventors have studied an aqueous polyurethane resin which does not impair the superiority of the aqueous polyurethane containing polytetramethylene ether glycol and has little change in physical properties at low temperatures. It was found that the improvement was achieved by the water-based polyurethane resin shown in.

That is, the present invention relates to --CH ₂ CH (R ₁ )
A group represented by a CH (R ₂ ) CH ₂ O-group (wherein _one of R ₁ and R ₂ is hydrogen and the other is a methyl group) (Chemical Formula 1), and —CH ₂ CH ₂ CH ₂ It is composed of a group represented by CH ₂ O- (Chemical Formula 2) and the ratio of (Chemical Formula 1) is 5 to 30% by weight
An aqueous polyurethane resin comprising a random copolymerized polyol (A) which is a compound (A), a hydrophilicity-imparting substance (B) having at least one carboxyl group and at least two hydroxyl groups, and a polyisocyanate compound (C).

The polyol compound which is the component (A) constituting the aqueous polyurethane resin used in the present invention is --CH ₂
CH (R ₁₎ CH (R ₂₎ (In R _1, R ₂ is either hydrogen, the other is a is a methyl group) CH ₂ O-groups (of 1) represented by, chromatography CH ₂ It is composed of a group represented by CH ₂ CH ₂ CH ₂ O— (Chemical Formula 2), and the polymerization mode of these structural units is random copolymerization. Such polyol (A) is, for example, tetrahydrofuran (hereinafter THF).
And 3-methyltetrahydrofuran molar ratio 85/15
To a 20/80 mixture of strong acids capable of ring-opening THF,
For example, it is a random copolymerized polyether dihydroxy compound obtained by copolymerization with chlorosulfonic acid, fluorosulfonic acid, perchloric acid, etc., usually at a temperature of 0 ° C to 50 ° C. The usable molecular weight of this polyether A is 600
˜5,000, preferably 1500 to 3500.
When the molecular weight of polyether A is less than 600, the obtained aqueous polyurethane resin becomes a resin having poor rubber elasticity,
If the molecular weight is more than 5,000, the viscosity during the urethanization reaction will increase sharply and the workability will be significantly deteriorated. (Chemical formula 1)
In represented by over _{CH 2 CH (R 1) CH} (R 2) CH 2 O- group, 3-methylstyrene in tetrahydrofuran (hereinafter 3-methyl-TH
It is contained in the polyol (A) used in the present invention in an amount of 5 to 30% by weight by the group given by F).

The hydrophilicity-imparting substance (B) having at least one carboxyl group (group for emulsifying a polyurethane compound to be formed) and at least two hydroxyl groups used in the present invention is, for example, 2,2-dimethylol. A molar ratio of trifunctional polyols obtained by addition polymerization of propionic acid, trimethylolpropane or glycerin, etc. with an initiator such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc. and cyclic acid anhydride such as isophthalic acid, maleic acid. A half-ester compound (number average molecular weight 90 to 3000) having at least one carboxyl group and at least two hydroxyl groups in the molecule obtained by the addition reaction by ring opening at 1: 1 is mentioned.

The polyisocyanate compound (C) used in the present invention is 2,4-tolylene diisocyanate, 2,6
-Tolylene diisocyanate, 4,4-'diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,4
-Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,3,5-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dimethyl-3,3'-diphenyl diisocyanate, 1,5 naphthalene diisocyanate,
It is a well-known isocyanate such as p-phenylene diisocyanate and m-phenylene diisocyanate, and there may be a system in which two or more kinds of these are mixed.

In the aqueous polyurethane resin according to the present invention, first, the polyol of the component (A) and the polyisocyanate compound of the component (C) have an isocyanate equivalent of (C) / hydroxyl equivalent of (A) of 1.0 to 4.7. To produce a both-end isocyanate urethane prepolymer, which is then chain-extended by the reaction of the component (B), which is a hydrophilicity-imparting substance having at least one carboxyl group and at least two hydroxyl groups, A prepolymer of both-terminal isocyanate having a carboxyl group introduced therein is constituted, and the composition ratio thereof is such that the isocyanate equivalent ratio of (C) / hydroxyl equivalent ratio of (A) + (B) is 1.1 to 2.
And the carboxyl group content in the prepolymer is in the range of 0.2 to 2.0% by weight. If the isocyanate equivalent ratio of (C) / hydroxyl equivalent ratio of (A) + (B) is less than 1.1, the heat resistance will be poor, and if it exceeds 2.5, the heat melting property will be poor and the object cannot be achieved. In addition, the hydrophilic group content in the prepolymer is 0.2
If the amount is less than the above range, the hydrophilicity is poor and the emulsion is not dispersed.

In the case of the One-Sailboat method, the reaction is carried out at a ratio of (isocyanate equivalent of (C) / (polyol of (A) component + hydroxyl of (B) component) equivalent ratio of 1.1 to 2.5 to react in the molecule. A carboxyl group-introduced isocyanate urethane prepolymer having both terminals is constituted.

These urethanization reactions can be prepared either in the presence of an organic solvent or in the absence of a solvent, and also in the presence of a small amount of a reaction catalyst such as an organotin compound or a tertiary amine or in the absence of a catalyst. It is a urethanization reaction.

The thus obtained urethane prepolymer having a carboxyl group introduced therein is neutralized by placing it in an aqueous solution in which a compound having an ionic property opposite to that of the carboxyl group such as an alkali metal, an alkaline earth metal or an organic base is dissolved. A hydrophilic salt is formed by the reaction and stably dispersed as a high molecular weight substance in water to produce an aqueous polyurethane resin. Tertiary and quaternary amine compounds can be used as the organic base. In addition, as the carboxylate group generated at that time, -COOH, -COONa, -COO
NH ₄ etc. can be mentioned.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples.
A group represented by —CH ₂ CH (R ₁ ) CH (R ₂ ) CH ₂ O— (R ₁ and R ₂ are as defined above), and —CH ₂ CH ₂ CH ₂
The polyol (A) composed of a group represented by CH ₂ O- is abbreviated as PTG-L. PTG-L2000: Hodogaya Chemical Co., Ltd., average molecular weight of 2000, over _{CH 2 CH (R 1) CH} (R 2) CH 2 O
-Containing 15% by weight of Coronate T-80: Nippon Polyurethane Co., Ltd .: 2,4 and 2,6 tolylene diisocyanate having an isomer pair of 8: 2 [Example 1] Thermometer, stirring device, cooling with drying tube PTG with a hydroxyl value of 56.1 is placed in a four-necked flask equipped with a tube.
Charge 396 parts by weight of L2000, Coronate T-8
70 parts by weight of 0 was added and reacted at a system temperature of 85 ° C. for 3.5 hours to obtain a urethane prepolymer containing 3.68% by weight of active isocyanate. Then, while maintaining the temperature at 85 ° C., 35 parts by weight of a half-ester compound having a hydroxyl value of 215.6 obtained by an equimolar reaction of a triol having a hydroxyl value of 402.8 and maleic anhydride was added and reacted for 4 hours to give an active isocyanate of 2 A urethane prepolymer of isocyanate having a carboxyl group introduced into the molecule and having both ends of the molecule was obtained. 400 parts by weight of the urethane prepolymer thus obtained was forcibly dispersed for 5 minutes using a homogenizer in water having a temperature of 40 ° C. in which 2 parts by weight of sodium hydroxide were dissolved in 357 parts by weight of water, and then 3 parts by weight.
The mixture was transferred to a container in which a stirring blade rotating at a speed of 00 rpm was set, and a chain extension reaction was carried out for 1 hour while maintaining the temperature at 70 ° C. This reaction is a decarboxylation reaction in which the isocyanate at the molecular end reacts with water. The polyurethane water dispersion thus obtained had a solid content of 53%, a hydrogen ion index (PH) of 7.1, and was an emulsion having a viscosity of 600 cps / 20 ° C. and excellent dispersion stability.

Comparative Example 1 A four-necked flask equipped with a thermometer, a stirrer, and a cooling tube with a drying tube had a hydroxyl value of 56.
396 parts by weight of PTG2000 of 1 was charged, 70 parts by weight of Coronate T-80 was added, and the temperature in the system was 85 ° C
3.68% by weight of active isocyanate after reacting for 3.5 hours
A urethane prepolymer containing was obtained. Then 85 ℃
The hydroxyl value obtained from the equimolar reaction of the triol having a hydroxyl value of 402.8 and maleic anhydride is 215.
35 parts by weight of the half-ester compound of No. 6 was added and reacted for 4 hours to obtain a urethane prepolymer of a molecule-terminated isocyanate having a carboxyl group introduced into a molecule containing 2.31% by weight of active isocyanate. 400 parts by weight of the urethane prepolymer thus obtained was dissolved in 2 parts by weight of sodium hydroxide in 357 parts by weight of water, and the temperature was 40 ° C.
Force disperse in water for 5 minutes using a homogenizer,
Next, it was transferred to a container in which a stirring blade rotating at a speed of 300 rpm was set, and a chain extension reaction was carried out for 1 hour while maintaining the temperature at 70 ° C. This reaction is a decarboxylation reaction in which the isocyanate at the molecular end reacts with water. The polyurethane aqueous dispersion thus obtained had a solid content of 53%, a hydrogen ion index (PH) of 7.1, and a viscosity of 690 cps / 20.
The emulsion was excellent in dispersion stability at ℃.

Manufacture of Specimens The aqueous polyurethane emulsions obtained in Examples and Comparative Examples, B-20 (water resistance improver manufactured by Hodogaya Chemical Co., Ltd.) and water were mixed at a ratio of 100: 1: 99. Stir for minutes. After that, 20cm × 30c which was fixed horizontally beforehand
45 g of the compounding liquid was poured into a m × 0.2 cm glass frame, and naturally dried in a thermostatic chamber at 20 ° C. for 48 hours to obtain a film having a thickness of 0.15 ± 0.05 mm. Then, the film was removed from the glass frame, dried in an oven at 110 ° C. for 2 hours, and then die-cut with a No. 3 dumbbell. After that, it was dried in an oven at 105 ° C. for 1 hour and then discharged in a desiccator to give a test sample.

Tensile Strength The test piece obtained as described above was heated at 20 ° C. and −20.
After being left for 15 minutes in a thermostatic chamber for a tensile tester set at 0 ° C., a tensile test was conducted at a set temperature. Tensile test is J
According to IS K6301, a universal tensile tester (Tensilon UTM-III) manufactured by Orientec Co., Ltd. was used.
The results are shown in Table 1 and FIG.

[0017]

[Table 1]

[0018]

As described above, according to the present invention, it is possible to provide a more flexible and elastic aqueous polyurethane resin in a low temperature region which cannot be obtained by the conventional aqueous polyurethane resin.

[0019]

[Brief description of drawings]

FIG. 1 shows the physical property values shown in Table 1 in FIG.
It is shown by an in curve.

Claims (1)

[Claims] 1. A CH ₂ CH (R ₁ ) CH (R ₂ ) CH ₂ O-
A group (Chemical Formula 1) represented by a group (one of R ₁ and R ₂ is hydrogen and the other is a methyl group), and —CH ₂ CH ₂
Random copolymerized polyol (A) composed of a group represented by CH ₂ CH ₂ O— (Chemical Formula 2) and having a ratio of (Chemical Formula 1) of 5 to 30% by weight; Aqueous polyurethane resin comprising a hydrophilicity-imparting substance (B) having one hydroxyl group and a polyisocyanate compound (C)