JPH06199974A - Polyurethane dispersion - Google Patents

Abstract

PURPOSE:To provide a polyurethane dispersion capable of economically giving porous sheet materials excellent in physical properties such as mechanical strength, appearance, and steam permeability. CONSTITUTION:In the polyurethane dispersion comprising (A) a polyurethane resin and (B) an organic solvent having a limitation on the mutual solubility with water, the polyurethane resin A is produced from a chain extender component and an urethane prepolymer component which is produced by reacting a polymer diol component having an average mol.wt. of >=4000 or the mixed components of two or more polymer diols containing the polymer diol having an average mol.wt. of >=4000 as an essential component with an excessive amount of an organic diisocyanate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to polyurethane dispersions, and more particularly to polyurethane dispersions that can provide porous sheet materials.

[0002]

2. Description of the Related Art Conventionally, as a natural leather substitute or the like, a method for producing a porous sheet material from a polyurethane resin solution or dispersion is known. They are roughly classified into a wet method and a dry method. The wet method has a drawback that the production cost is increased in terms of equipment and productivity because it takes a step of removing the solvent from the polyurethane polymer solution using a coagulation bath.

On the other hand, in the dry method, (1) a method using a foaming agent or a porous filler and (2) a water-in-oil emulsion of a polymer are prepared, and the boiling point difference between water and a solvent is utilized. And a method of obtaining a porous sheet. In the method of (1), when a sheet material is used, huge holes are generated,
There is a drawback that it is difficult to obtain sufficient physical properties by forming closed cells. Examples of the method (2) include the methods described in JP-B-48-8742, JP-B-58-48579 and JP-A-60-252638. Although these methods provide a homogeneous porous sheet material, they require selective evaporation of solvent and water and require rigorous temperature control in the drying process. Further, the polyurethane dispersion used for the water-in-oil emulsion is inferior in stability and easily gels, which makes it difficult to prepare the water-in-oil emulsion and difficult to store the polyurethane dispersion. .

[0004]

In view of the above problems of the prior art, the present invention makes it possible to economically produce a porous sheet material having excellent physical properties such as mechanical strength, appearance and water vapor permeability. An object of the present invention is to provide a polyurethane dispersion. The present inventors have conducted intensive studies to improve the above-mentioned drawbacks of the dry method, and as a result, found a polyurethane dispersion which can give excellent product quality and can be manufactured economically and stably. The present invention has been completed.

[0005]

In order to solve the above problems, the present invention provides a polyurethane dispersion comprising a polyurethane resin (A) and an organic solvent (B) having a limited mutual solubility with water. The resin (A) is prepared by reacting an excess amount of an organic diisocyanate with a polymer diol component having an average molecular weight of 4000 or more or a mixture component of two or more polymer diols having a polymer diol component having an average molecular weight of 4000 or more as essential components. Provided is a polyurethane dispersion, which is produced from the resulting urethane-based prepolymer component and a chain extender component.

The polyurethane resin (A) is obtained by producing an isocyanate-terminated prepolymer from a diol component containing a polymer diol having an average molecular weight of 4000 or more and an excess amount of an organic diisocyanate, and reacting this with a chain extender. To be As the polymer diol, polytetramethylene glycol, polypropylene glycol,
Polyalkylene glycol such as polyethylene glycol, polyester glycol such as polyethylene adipate having hydroxyl groups at both ends, polybutylene adipate, polyethylene butylene adipate, or poly-ε-caprolactone glycol, polycarbonate glycol obtained by reaction of glycol and dicarboxylic acid Alternatively, those containing a polyoxyethylene chain in these polymer diols can be used, and these can be used alone or in combination. These polymeric diol components are required to have an average molecular weight of 4000 or more, but within a range not exceeding 20% by weight of the polymeric diol component, the average molecular weight of the polymeric diol is 500 or more and 400 or more.
Those less than 0 can also be used.

If the average molecular weight is less than 4000, the stability of the polyurethane dispersion is poor, and the heat resistance of the resulting polyurethane resin is low, so that a good porous sheet cannot be obtained unless it is selected by the selective evaporation method. . In the polyurethane resin, the soft segment portion and the hard segment portion are microscopically phase-separated in the molecular chain, but when the molecular weight of the polymer diol used for the soft segment portion is 4000 or more, the hard segment portion (high melting point) (Part) has a large chain length and is excellent in heat resistance, and gelation during drying can occur quickly. On the other hand, when the molecular weight of the polymer diol is less than 4000, the chain length of the high melting point part is small and good. It is considered that it is difficult to obtain heat resistance.

As the organic diisocyanate, conventionally known 4,4'-diphenylmethane diisocyanate (MD
I), 2,4- and 2,6-tolylene diisocyanate, aromatic diisocyanates such as 1,3- and 1,4-xylylene diisocyanate, hydrogenated MDI, alicyclic diisocyanates such as isophorone diisocyanate,
Alternatively, an aliphatic diisocyanate such as 1,6-hexamethylene diisocyanate can be used.

As the chain extender, conventionally known glycols such as ethylene glycol and 1,4-butanediol,
Alternatively, diamines such as hexamethylenediamine and isophoronediamine can be used. The organic solvent having a limited mutual solubility with water used in the present invention,
Ketone-based solvents such as methyl ethyl ketone (MEK), methyl-n-propyl ketone, and methyl isobutyl ketone;
Methyl formate, ethyl formate, propyl formate, methyl acetate,
Ester solvents such as ethyl acetate and butyl acetate are preferred. Further, a solvent having a high mutual solubility with water, such as acetone and dioxane, and a solvent having a low mutual solubility with water, toluene,
It can be used by mixing a solvent such as xylene or n-hexane with a limit on mutual solubility with water, or by mixing an organic solvent with a limit on mutual solubility with water. It is also possible to use.

By producing a polyurethane polymer using the above-mentioned raw materials and solvent, the polyurethane polymer is obtained in an opaque dispersion state and is not partially solubilized in the organic solvent. As described above, when the average molecular weight of the polymer diol is 3,000 or less, the stability of the polyurethane dispersion is deteriorated when the average molecular weight of the polymer diol is in the range of 1500 to 3000, and the average molecular weight of the polymer diol is When it is less than 1500, the stability is relatively good, but the heat resistance is poor and it becomes difficult to obtain a good porous sheet. When a polymer diol component having an average molecular weight of 4000 or more and a polymer diol component having an average molecular weight of less than 4000 are used in combination, the polymer diol component having an average molecular weight of 4000 or more should be 80% by weight or more in the mixed components. In this case, good stability and heat resistance can be obtained.

In order to obtain a porous sheet from the polyurethane dispersion of the present invention, a step of preparing a water-in-oil emulsion from the polyurethane dispersion, coating or impregnating it with a substrate, and then drying it is employed. To prepare a water-in-oil emulsion, an appropriate amount of a water-in-oil emulsifier is added, and while stirring this with a homomixer, 50 to 50 parts by weight of the solid content in the polyurethane dispersion is added. A polyurethane emulsion is obtained by adding 500 parts by weight of water. At this time, as the water-in-oil type emulsifier, a conventionally known one such as Pluronic type emulsifier can be used, and the addition amount is 1 to 10 parts by weight with respect to 100 parts by weight of the solid content in the polyurethane dispersion. Is preferred. In addition, the obtained polyurethane emulsion, if necessary,
Various additives, for example, known additives such as colorants, cross-linking agents, stabilizers, fillers and the like can be optionally added.

[0012] As the substrate used when producing a porous sheet from the polyurethane emulsion thus obtained, woven cloth, knitted cloth, non-woven cloth, glass plate, metal plate, release paper,
Various materials such as a plastic film can be used.

[0013]

In order to obtain a porous sheet material from the polyurethane emulsion prepared from the polyurethane dispersion of the present invention, only a short drying step is required. For example, after coating or impregnating the base material with the emulsion, it is sufficient to dry the base material in a hot air dryer at 100 to 180 ° C. for 1 to 5 minutes. That is, a complicated process such as a pretreatment process described in JP-B-55-18249 and JP-B-58-48579 is unnecessary, and JP-B-60 / 60
There is no need for two-step drying as shown in Japanese Patent Publication No. 252638.

The porous sheet material thus obtained is useful as shoes, bags, furniture, clothing, waterproof cloths, air filters, filter materials, etc. as leather substitutes.

[0015]

EXAMPLES Next, the present invention will be described in detail with reference to examples. In the examples, parts and% indicate parts by weight and% by weight, respectively. Examples 1 to 4 (1) Polytetramethylene glycol (average molecular weight of about 4
000, hydroxyl value 28) 400 parts, MDI 190 parts and triethylenediamine (catalyst) 0.3 parts with MEK65
Add to 0 parts and react at 70 ° C for 2 hours, then MEK1240
Part, 40 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate (catalyst) were added, and the reaction was continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring and had a concentration of 25% and a viscosity of 11,000 cps./20.
A polyurethane dispersion (A) which was clouded at ℃ was obtained.

(2) 500 parts of polycarbonate diol (average molecular weight: about 5000, hydroxyl value: 22), MDI20
MEK78 with 5 parts and 0.3 parts triethylenediamine
In 5 parts, after reacting at 70 ° C. for 2 hours, MEK1459
Part, ethylene glycol 43 parts and dibutyltin dilaurate 0.05 part were added, and the reaction was further continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring to obtain a turbid polyurethane dispersion (B) having a concentration of 25% and a viscosity of 10,000 cps./20°C.

(3) Polyethylene adipate diol (average molecular weight about 4000, hydroxyl value 28) 400 parts, M
Add 205 parts DI and 0.3 parts triethylenediamine to M
Add to 680 parts of EK and react at 70 ° C for 2 hours, then MEK
1264 parts, 43 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate were added, and the reaction was further continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring and had a concentration of 25% and a viscosity of 9,000 cps./20°C.
A turbid polyurethane dispersion (C) was obtained.

(4) Average molecular weight of about 4000 (hydroxyl value 2
400 parts of polytetramethylene glycol of 8), 63 parts of polytetramethylene glycol having an average molecular weight of about 1000 (hydroxyl value 112), 214 parts of MDI and 0.3 part of triethylenediamine are added to 755 parts of MEK, and the mixture is heated to 70 ° C.
After 2 hours of reaction, 1402 parts of MEK, 42 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate were added, and the reaction was continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring to obtain a cloudy polyurethane dispersion (D) having a concentration of 25% and a viscosity of 11,000 cps./20°C. Comparative Examples 1 to 4 (1) Polytetramethylene glycol (average molecular weight about 1
000, hydroxyl value 112) 400 parts, MDI 256 parts and triethylenediamine 0.3 part were added to MEK 730 parts, and after reacting at 70 ° C. for 2 hours, MEK 1349 parts, ethylene glycol 37 parts and dibutyltin dilaurate 0.05 parts were added. The reaction was further continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring to obtain a cloudy polyurethane dispersion (E) having a concentration of 25% and a viscosity of 12,000 cps./20°C.

(2) 400 parts of polytetramethylene glycol (average molecular weight about 2000, hydroxyl value 56), MDI
MEK with 205 parts and 0.3 parts of triethylenediamine
In 675 parts, after reacting at 70 ° C. for 2 hours, MEK12
51 parts, 37 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate were added, and the reaction was further continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring and had a concentration of 25% and a viscosity of 10,000 cps./20°C.
To obtain a turbid polyurethane dispersion (F).

(3) 300 parts of polytetramethylene glycol (average molecular weight: about 3000, hydroxyl value: 37), MDI
MEK with 146 parts and 0.3 parts of triethylenediamine
Add to 500 parts and react at 70 ° C for 2 hours, then MEK92
5 parts, 29 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate were added, and the reaction was continued at 70 ° C. for 6 hours. Cool the reaction mixture to room temperature with stirring,
A cloudy polyurethane dispersion (G) having a concentration of 25% and a viscosity of 13,000 cps./20° C. was obtained.

(4) Average molecular weight of about 4000 (hydroxyl value 2
200 parts of polytetramethylene glycol of 8), 200 parts of polytetramethylene glycol having an average molecular weight of about 1000 (hydroxyl value 112), 229 parts of MDI and 0.3 part of triethylenediamine are added to 700 parts of MEK to give 70 parts.
After reacting at 2 ° C. for 2 hours, 1307 parts of MEK, 40 parts of ethylene glycol and 0.05 part of dibutyltin dilaurate were added, and the reaction was continued at 70 ° C. for 6 hours. The reaction mixture was cooled to room temperature with stirring to obtain a cloudy polyurethane dispersion (H) having a concentration of 25% and a viscosity of 12,000 cps./20°C. Examples 5 to 12 and Comparative Examples 5 to 12 Each of the polyurethane dispersions of Examples 1 to 4 and Comparative Examples 1 to 4 was stirred with a homomixer together with an emulsifier, an organic solvent and water to prepare respective polyurethane emulsions. Then, it was applied on a glass plate and then dried. The formulation and the like are shown below.

Polyurethane dispersion 100 parts Pluronic emulsifier 2 parts Methyl ethyl ketone 20 parts Toluene 20 parts Water 50 parts Emulsion solid content concentration 14.1% Coating amount 200 g / m ² Drying conditions of Examples 5 to 12, emulsion The liquid viscosity and the physical properties of the obtained sheet are shown in Table 1. The water vapor transmission rate is JIS
According to the L-1099 A-1 method.

[0023]

[Table 1]

Table 2 shows the drying conditions of Comparative Examples 5 to 12, the viscosity of the emulsion and the physical properties of the obtained sheets.

[0025]

[Table 2]

As described above, the polyurethane dispersion of the present invention has good stability, and a uniform porous sheet material excellent in moisture permeability can be obtained only by drying for a short time.

[Procedure amendment]

[Submission date] March 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009] The chain extension length agent, conventionally known ethylene glycol, glycols such as 1,4-butanediol,
Alternatively, diamines such as hexamethylenediamine and isophoronediamine can be used. The organic solvent having a limited mutual solubility with water used in the present invention,
Ketone-based solvents such as methyl ethyl ketone (MEK), methyl-n-propyl ketone, and methyl isobutyl ketone;
Methyl formate, ethyl formate, propyl formate, methyl acetate,
Ester solvents such as ethyl acetate and butyl acetate are preferred. Further, a solvent having a high mutual solubility with water, such as acetone and dioxane, and a solvent having a low mutual solubility with water, toluene,
It can be used by mixing a solvent such as xylene or n-hexane with a limit on mutual solubility with water, or by mixing an organic solvent with a limit on mutual solubility with water. It is also possible to use.

Claims (2)

[Claims] 1. A polyurethane dispersion comprising a polyurethane resin (A) and an organic solvent (B) having a limited mutual solubility with water, wherein the polyurethane resin (A) is a polymer diol component having an average molecular weight of 4000 or more. Alternatively, it is produced from a urethane prepolymer component obtained by reacting an excess amount of an organic diisocyanate with a mixed component of two or more polymer diols having a polymer diol component having an average molecular weight of 4000 or more as an essential component, and a chain extender component. A polyurethane dispersion, characterized in that 2. The polymer diol component has an average molecular weight of 400.
The polyurethane dispersion according to claim 1, containing 80% by weight or more of 0 or more components.