JPS6156260B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a film-forming urethane emulsion that is soft to the touch and has excellent impact resilience, and relates to a urethane emulsion that has excellent performance as an intermediate layer, impregnating agent, and adhesive for synthetic leather. Conventionally, the urethane resin used for these has been used in the form of an organic solvent solution, but when organic solvents are used, there are various problems (for example, toxicity, flammability,
Because of this (air pollution, etc.), there is a demand for the development of a urethane emulsion that can provide a resin film with the same performance as that obtained from a solvent solution, and although various studies have been conducted, none has yet been satisfactory. In organic solvent-based urethane resins that are generally used for synthetic leather, polyester diols and polytetramethylene diol are used as polyol components, and 4.
It is known that a film or sheet with excellent impact resilience can be obtained by using 4'-diphenylmethane diisocyanate in combination with a low molecular weight diol. However, when these findings were directly applied to the field of urethane emulsions, it was found that the resulting films and sheets had poor film formation properties and a hard texture, making them unsuitable for practical use. . The present inventor has conducted extensive research on urethane emulsions that have excellent performance when used primarily as intermediate layers of synthetic leather, infiltrating agents, and adhesives, and has found that they have excellent impact resilience and film-forming properties, which are necessary for these applications. The present inventors have achieved the invention of a urethane emulsion that can produce a film or sheet with a soft texture. That is, the present invention provides a urethane emulsion consisting of polyurethane and water obtained by reacting a prepolymer with excess NCO groups of polyol and polyisocyanate with a chain extender in the presence of water, in which the polyol has a molecular weight of 500 to 500.
3000 polyester polyol (A), molecular weight 200~
5000 polyoxyalkylene (C ₂ - C ₃ ) polyol (B) and optionally a low molecular polyol (C), and the average molecular weight of (A), (B) and (C) mixed is 1000 - 3000
It is a film-forming urethane emulsion with a soft texture and excellent impact resilience, characterized by a weight ratio (A/B+C) of 10 to 0.5. In the NCO group-excessive prepolymer obtained by reacting the polyol and polyisocyanate used in the present invention, the polyols include polyester polyol (A) with a molecular weight of 500 to 3000, polyoxyalkylene (C ₂ to
C ₃ ) polyol (B) and, if necessary, a polyol consisting of a low molecular weight polyol (C) other than (A) and (B). The polyester polyol (A) having a molecular weight of 500 to 3000 includes polyols such as ethylene glycol, propylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol, and succinic acid. , glutaric acid, adipic acid, maleic acid,
Among polyester polyols obtained by reacting with polycarboxylic acids such as fumaric acid, phthalic acid, and trimellitic acid, those having a molecular weight within the above-mentioned range can be mentioned. Among these, polyester diols such as polyethylene adipate, polypropylene adipate, polybutylene adipate, polyethylene butylene adipate, and polydiethylene adipate having a molecular weight of 500 to 3000 are preferred. If (A) with a molecular weight of less than 500 is used, the resulting film or sheet will become hard and have poor film formability. Furthermore, if a material larger than 3000 is used, it becomes soft but the rebound resilience decreases.
The above-mentioned polyoxyalkylene ( _C2 - _C3 ) polyol (B) having a molecular weight of 200-5000 includes ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol,
Among adducts of one or more types of alkylene oxides such as ethylene oxide and propylene oxide of polyols such as sorbitol (in the case of adducts of two or more types, block or random adducts), those having a molecular weight within the above-mentioned range can be mentioned. Among these, polyoxypropylene glycol with a molecular weight of 500 to 3000, ethylene oxide adducts of polyoxypropylene glycol (ethylene oxide addition weight ≦ 20%), propylene oxide adducts of polyols such as glycerin and trimethylolpropane,
Further, it is preferable to add ethylene oxide to this (weight of ethylene oxide added≦40%). If (B) is used that has a molecular weight of less than 200, the resulting film or sheet will become hard and have poor film formability. Also, if a material larger than 5000 is used, it will become softer, but the rebound resilience will decrease. In addition, the above-mentioned low molecular polyols (C) include ethylene glycol, propylene glycol, butanediol, neopentyl glycol,
2-4 mole ethylene oxide adduct of 1,6-hexanediol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, hydroquinone, 2-4 mole ethylene oxide adduct of 2,2-bisphenolpropane Examples include polyols. Among these, ethylene glycol, propylene glycol, butanediol, diethylene glycol, and dipropylene glycol are preferred. The polyol used in the present invention has a mixed average molecular weight (referred to as average molecular weight) of (A), (B), and (C) of 1000 to 1000.
2500 and the weight ratio (A/B+C) is 8 to 0.5. If A/B+C>8, the film forming property will decrease, if A/B+C<0.5 or average molecular weight>2500, impact resilience will be poor, and if average molecular weight <1000, the feel will be hard. The low-molecular polyol (C) is added as necessary, and its amount in the polyol is not particularly limited, but it is usually 0 to 10% (by weight), preferably 0 to 5% (by weight) in the total polyol. be. The average number of functional groups in all polyols is not particularly limited, but is preferably from 2 to 2.5 in order to obtain a coating with a particularly soft texture. As the polyisocyanate, all conventional aromatic and aliphatic polyisocyanate compounds can be used. For example 2,4- and 2,6-tolylene diisocyanate (TDI),
Aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane- 4,4'-diisocyanate (HMDI) 3-isocyanatomethyl-3,5.
Examples include aliphatic polyisocyanates such as 5-trimethylcyclohexyl isocyanate (IPDI) and 2,6-diisocyanate methyl caproate (LDI), mixtures thereof, and di- or trimers thereof. Among these, 2,4- and 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), 1,6-hexamethylene diisocyanate (HDI) is preferred. A prepolymer containing polyol and polyisocyanate with excess NCO groups may be produced by a conventional method. For example, polyol and polyisocyanate are mixed at a molar ratio of excess NCO groups, usually 50 to 50%.
This is carried out by stirring under a nitrogen stream at a temperature of 100°C. In this case, reaction control additives such as benzoyl chloride, phthalic anhydride, phosphoric acid, benzoic acid, p-toluenesulfonic acid, Lewis acids such as _BF3 , dibutyltin dilaurate, lead octylate, triethylene diamine, etc. reaction accelerator additives, in some cases dimethylformamide, toluene, xylene, dioxane, acetone, methyl ethyl ketone, tetrahydrofuran,
Organic solvents that do not react with NCO groups may be present, such as ethyl acetate, trichlorethylene, perchlorethylene, and the like. The chain extender used in the present invention may be the same as that used in the production of ordinary urethane resins, for example, at least two chain extenders selected from primary and secondary amino groups in one molecule. Examples include water-soluble polyamines having an amino group and emulsified dispersions of amine compounds. Among these, water-soluble aliphatic polyamines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, xylylenediamine, diethylenetriamine, triethylenetetramine, etc., and water-soluble alicyclic polyamines such as piperazine are preferred. There is no particular limit to the amount of chain extender used, but usually
0.1 to NCO groups in NCO group-excess prepolymer
The amount may be any amount as long as it contains an amino group of 2 equivalents, preferably 0.3 to 1 equivalent. There are no particular limitations on the method for producing emulsions.
It can be prepared by adding an NCO group-excessive prepolymer, a chain extender, water and, if necessary, an emulsifier in any order and emulsifying the mixture. (Water also partially reacts at this time.) Specifically, for example, (1) a method of mixing an NCO-excess prepolymer and an emulsifier, adding water while stirring to emulsify, and adding a chain extender; 2) In an aqueous solution containing a chain extender and an emulsifier, under strong stirring.
Method of adding NCO-rich prepolymer, (3)
A method in which the NCO group-excessive prepolymer is emulsified with an emulsifier and then mixed separately with an aqueous solution or emulsion of a chain extender, (4) the NCO group-excess prepolymer and the chain extender are separately added to an aqueous solution containing an emulsifier while stirring vigorously. and (5) a method of strongly mechanically emulsifying the NCO group-excess prepolymer, chain extender, and water without using an emulsifier. Among these, methods (1) and (3) are preferred. In preparing these emulsions, it is preferable to add a chain extender while all of the NCO groups in the NCO-rich prepolymer have not reacted with water, in order to improve the stability of the emulsion and the strength of the resulting film.
The reaction between the NCO group-excessive prepolymer, water, and chain extender usually proceeds during mixing during the emulsification and dispersion process, but it may be heated to about 30 to 70°C to accelerate the reaction. In addition, if the reaction is vigorous or progresses too much, the reaction may be carried out with cooling. Also in the emulsification and dispersion step, reaction control additives, reaction accelerating additives, solvents, etc., which can be used when preparing the NCO group-excessive prepolymer, can be added. Examples of emulsifiers include higher alcohols, alkylphenols,
Nonionic surfactants such as arylphenols and ethylene oxide adducts such as polyoxypropylene glycol; anionic surfactants such as sulfate ester salts and alkylbenzene sulfonates of ethylene oxide adducts such as alkylphenols and higher alcohols; and mixtures thereof are preferred. The amount of emulsifier used may be 0 to 30% by weight, more preferably 3 to 12% by weight based on the resin content. Stirring may be carried out using an ordinary stirring device, but in order to make the particles of the emulsion as small as possible and improve film-forming properties, it is preferable to use an emulsifying device such as a homomixer, homogenizer, or disper mill. The concentration of the urethane emulsion finally obtained is not particularly limited, but is usually 20 to 60% by weight, preferably 30 to 50% by weight. The urethane emulsion of the present invention is characterized by good stability, and when formed into a film, provides a film with excellent impact resilience and soft texture. In the present invention, when only a polyester polyol is used as the polyol, the impact resilience is good, but the film forming property (film forming property) is very poor and the texture is hard. Also, polyoxyalkylene (C ₂ ~
C ₃ ) When only polyol is used, the film formation properties are good and the texture is soft, but the impact resilience is poor. Polyester polyol, polyoxyalkylene (C ₂ ~
Even if a C ₃ ) polyol and, if necessary, a low-molecular-weight polyol are used, if a polyol outside the range described in the present invention is used, the impact resilience, film-forming properties, and texture will be insufficient. The urethane emulsion of the present invention can be used as a coating agent, an adhesive, a paint vehicle, an ink vehicle, and an impregnation agent for base fabrics such as woven fabrics, knitted fabrics, and non-woven fabrics when manufacturing synthetic leather. It is also useful as a modification modifier used in emulsions of resins such as vinyl, rubber latexes such as natural rubber, SBR, NBR, etc., and as a texture modifier for textiles. The present invention will be further explained below with reference to Examples.
The present invention is not limited to these. Example 1 A mixture of 700 parts of polyethylene butylene adipate (average molecular weight: 2500) and 100 parts of polyoxypropylene glycol (average molecular weight: 950) was
200 parts of 4'-diphenylmethane diisocyanate was added and reacted with stirring under a nitrogen stream in a reaction vessel to obtain a urethane prepolymer containing 3.5% of terminal free isocyanate groups. To 100 parts of this urethane prepolymer, 2 parts of an anionic surfactant (sulfuric ester salt of 6 moles of ethylene oxide adduct of nonylphenol) and a nonionic surfactant [polyoxypropylene glycol (molecular weight approx.
Add a mixture of 10 moles of ethylene oxide (2000) and 8 parts of ethylene oxide, mix well, and add 100 parts of water.
14 parts of a 13% aqueous solution of piperazine was added to this and stirred for about 30 minutes to determine the particle size.
A stable emulsion over time with a particle size of 0.5 to 1 μm and a resin content of about 50% was obtained. Example 2 A mixture of 600 parts of polyethylene butylene adipate (average molecular weight: 2000) and 150 parts of polyoxypropylene glycol (average molecular weight: 900) was
250 parts of 4'-diphenylmethane diisocyanate was added and reacted with stirring under a nitrogen stream in a reaction vessel to obtain a urethane prepolymer containing 4.5% of terminal free isocyanate groups. A mixture of 100 parts of this urethane prepolymer and two types of nonionic surfactants [2 parts of 40 moles of ethylene oxide adduct of nonylphenol and 8 parts of 10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight approximately 2000)] was added to 10 parts of this urethane prepolymer. After adding 100 parts of water and emulsifying and dispersing the mixture with thorough stirring, add 13 parts of a 13% aqueous solution of piperazine and stir for about 30 minutes. An emulsion stable over time of % was obtained. Example 3 A mixture of 350 parts of polyethylene butylene adipate (average molecular weight: 2500) and 400 parts of polyoxypropylene glycol (average molecular weight: 900) was added with a mixture ratio of tolylene diisocyanate (2, 4-, 2, 6-isomers). Add 100 parts of 80:20) and 150 parts of 4,4'-diphenylmethane diisocyanate and stir in a reaction vessel under a nitrogen stream to react.
A urethane prepolymer containing 5% terminal free isocyanate groups was obtained. A mixture of 100 parts of this urethane prepolymer and two types of nonionic surfactants [2 parts of 40 moles of ethylene oxide adduct of nonylphenol and 8 parts of 10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight approximately 2000)] was added to 10 parts of this urethane prepolymer. add part,
After stirring and mixing well, add 100 parts of water to emulsify and disperse, and then add 15 parts of hexamethylene diamine to the mixture.
Add 23 parts of % aqueous solution and stir for about 30 minutes until the particle size is 0.5~
An emulsion with a diameter of 1μ and a resin content of approximately 50% was obtained which was stable over time. Example 4 Tolylene diisocyanate (2,4-,
2,6-isomer mixing ratio 80:20) 40 parts and 150 parts of 4,4'-diphenylmethane diisocyanate
The mixture was stirred and reacted in a reaction vessel under a nitrogen stream to obtain a urethane prepolymer containing 3.5% of terminal free isocyanate groups. To 100 parts of this urethane prepolymer, 10 parts of a mixture of two types of nonionic surfactants [2 parts of 40 moles of ethylene oxide adduct of nonylphenol and 8 parts of 10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight about 2000)] After stirring and mixing well, add 100 parts of water to emulsify and disperse, then add 13 parts of a 13% aqueous solution of piperazine and stir for about 30 minutes to obtain a particle size of 0.5 to 1μ and a resin content of about 50%. An emulsion that was stable over time was obtained. Example 5 Tolylene diisocyanate (2,4-, 2.6-isomer mixing ratio is 80:
20) was added and reacted with stirring under a nitrogen stream in a reaction vessel to obtain a urethane prepolymer containing 5.8% of terminal free isocyanate groups. A mixture of 100 parts of this urethane prepolymer and two types of nonionic surfactants [2 parts of 40 moles of ethylene oxide adduct of nonylphenol and 8 parts of 10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight approximately 2000)] was added to 10 parts of this urethane prepolymer. add part,
After stirring and mixing well, add 95 parts of water to emulsify and disperse, then add 20 parts of a 13% aqueous solution of piperazine and stir for about 30 minutes. A stable emulsion was obtained. Comparative Example 1 4.
300 parts of 4'-diphenylmethane diisocyanate was added and reacted with stirring under a nitrogen stream in a reaction vessel to obtain a urethane prepolymer containing 5% terminal free isocyanate groups. To 100 parts of this urethane prepolymer, 2 parts of an anionic surfactant (sulfuric ester salt of 6 moles of ethylene oxide adduct of nonylphenol) and 10 moles of ethylene oxide of polyoxypropylene glycol (molecular weight approximately 2000) were added to the nonionic surfactant. After adding 8 parts of the mixture with 8 parts of piperazine and stirring well, add 100 parts of water to emulsify and disperse the mixture. Add 13 parts of a 13% aqueous solution of piperazine to this and stir for about 30 minutes to obtain a particle size of 0.5 to 1μ.
A stable emulsion over time with a resin content of approximately 50% was obtained. Comparative Example 2 Tolylene diisocyanate (2.4-, 2.6) was added to a mixture of 540 parts of polyoxypropylene glycol (average molecular weight: 950) and 190 parts of propylene oxide adduct of glycerin (average molecular weight: 1000).
- Add 270 parts of isomer mixture ratio 80:20),
The mixture was stirred and reacted in a reaction vessel under a nitrogen stream to obtain a urethane prepolymer containing 5.8% terminal free isocyanate groups. This urethane prepolymer
100 parts, 2 parts of anionic surfactant (sulfuric ester salt of 6 moles of ethylene oxide adduct of nonylphenol) and 8 parts of nonionic surfactant [10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight approximately 2000)] Add a mixture of
The emulsion was stirred for about 30 minutes to obtain a stable emulsion with a particle size of 0.5 to 1 μm and a resin content of about 50% over time. Comparative Example 3 750 parts of polyethylene butylene adipate (average molecular weight: 1500) and 250 parts of 4,4'-diphenylmethane diisocyanate were added and reacted with stirring under a nitrogen stream in a reaction vessel, resulting in a product containing 4.2% of terminal free isocyanate groups. A urethane prepolymer was obtained. To 100 parts of this urethane prepolymer was added 10 parts of a mixture of two types of nonionic surfactants [2 parts of a 40 mole ethylene oxide adduct of nonylphenol and 8 parts of a 10 mole ethylene oxide adduct of polyoxypropylene glycol (molecular weight 2000)]. In addition, 97 parts of water was added to the well-stirred mixture to emulsify and disperse, and then 17 parts of a 13% aqueous solution of piperazine was added to this and stirred for about 30 minutes to obtain a particle size of 0.5 to 1μ and a resin content of about
An emulsion that was 50% stable over time was obtained. Comparative Example 4 A mixture of 550 parts of polyethylene butylene adipate (average molecular weight: 1000) and 100 parts of polyoxypropylene glycol (average molecular weight: 400),
4,4'-diphenylmethane diisocyanate 350
The mixture was stirred and reacted in a reaction vessel under a nitrogen stream to obtain a urethane prepolymer containing 5% terminal free isocyanate groups. A mixture of 100 parts of this urethane prepolymer and two types of nonionic surfactants [2 parts of 40 moles of ethylene oxide adduct of nonylphenol and 8 parts of 10 moles of ethylene oxide adduct of polyoxypropylene glycol (molecular weight approximately 2000)] was added to 10 parts of this urethane prepolymer. After adding 94 parts of water and emulsifying and dispersing the mixture with thorough stirring, add 23 parts of a 15% aqueous solution of hexamethylene diamine and stir for about 30 minutes to obtain a particle size of 0.5 to 1μ and a resin content. about
An emulsion that was 50% stable over time was obtained. Example 6 100 parts of each of the emulsions obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were mixed with 10 parts of an alkali thickened acrylic emulsion, and further Nopco DC-
100A (Ammonium stearate San Nopco Co., Ltd.)
Product) 5 parts were added to increase the viscosity, and the cream was foamed to about twice its size using a cream whisk. The creamy foam thus obtained was coated on release paper to a thickness of about 1 mm and heated at 140° C. for 3 to 4 minutes to obtain a foam sheet with dense cells. Performance tests (hand feel, impact resilience, film forming properties) were conducted on these sheets. The results are shown in Table-1.

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【table】

Claims (1)

[Claims] 1 NCO of polyol and polyisocyanate
In a urethane emulsion consisting of polyurethane and water obtained by reacting a group-rich prepolymer with a chain extender in the presence of water, the polyol has a molecular weight of
Polyester polyol (A) from 500 to 3000, molecular weight
200 to 5000 polyoxyalkylene (C ₂ to C ₃ ) polyol (B) and optionally low molecular polyol (C)
and the mixed average molecular weight of (A), (B), and (C) is
1000-2500, weight ratio [A/(B+C)] is 8-0.5
A film-forming urethane emulsion with a soft texture and excellent impact resilience.