JP3304056B2 - Polyurethane urea foam sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane urea foam sheet obtained by reacting and solidifying a urethane prepolymer having an isocyanate group at an end in a humidified and heated atmosphere. The present invention relates to a polyurethane urea foam sheet.

[0002]

2. Description of the Related Art Conventionally, synthetic leather and artificial leather have been used as substitutes for natural leather.
A polyurethane urea foam sheet obtained by reacting and solidifying a urethane prepolymer having an isocyanate group at an end in a humidified and heated atmosphere is laminated with a fiber base material, or a polyurethane skin layer is laminated with a polyurethane skin layer. Are known.

On the other hand, as an alternative to natural leather, a fiber-based material is impregnated with a water-miscible organic solvent solution such as dimethylformamide of a polyurethane elastomer, applied, and then coagulated in a non-solvent such as water. What is obtained by what is called a wet method which forms a microporous layer by the method is known.

[0004]

The synthetic leather and the artificial leather obtained by the above-mentioned wet method have a favorable texture, but are expensive because of the complicated manufacturing process. On the other hand, synthetic leather using a polyurethane urea foam sheet manufactured under various conditions which are conventionally considered to be preferable,
Although the manufacturing process was simple and inexpensive, the texture was far from that obtained by the above wet method.

Further, the synthetic leather using the polyurethane urea foam sheet is inferior in low-temperature characteristics (cold resistance) in addition to the problem of poor texture as described above, and -5.
Although there is a problem that an extreme increase in modulus is observed even at a temperature of about 5 ° C. to 5 ° C., this problem has not been solved, and the use of the synthetic leather using the polyurethane urea foam sheet is limited. was there.

The present inventor has conducted intensive studies to improve the feeling and low-temperature characteristics of synthetic leather using the above-mentioned polyurethane urea foam sheet, without being bound by various conditions which have been said to be preferable. By controlling the conditions in each reaction step to obtain a foamed sheet, the weight average molecular weight of the polyurethane urea in the obtained polyurethane urea foamed sheet is within a specific range, and if it has a glass transition point Having a texture comparable to synthetic leather and artificial leather obtained by the wet method, and obtaining a synthetic leather excellent in flexibility and low-temperature properties, and the polyurethane urea foam sheet thus obtained is For adhesive tape substrate, found that it can be suitably used for flooring, etc.,
The present invention has been completed.

[0007]

Means for Solving the Problems The polyurethane urea foamed sheet of the present invention made to solve the above-mentioned problems can be obtained by reacting a glycol with diisocyanate to obtain a urethane prepolymer having a terminal isocyanate group. A coating liquid obtained by adding a crosslinking agent and a catalyst to the mixture and mixing the air containing moisture, reacting and solidifying in a humidified, heated atmosphere, and a portion having a thickness of 0.2 to 1.0 mm. A crosslinked polyurethane urea foam sheet, by controlling various conditions in each step to obtain a polyurethane urea foam sheet, the polyurethane urea in the obtained polyurethane urea foam sheet, the weight average molecular weight measured by liquid chromatography Is 2 in terms of polystyrene
It is characterized in that it is in the range of 10,000 to 500,000 and has a glass transition point. By laminating the polyurethane urea foam sheet of the present invention with a fiber base material, a synthetic leather having a texture comparable to synthetic leather and artificial leather obtained by a wet method, and having excellent flexibility and low-temperature properties can be obtained. Also, it can be suitably used as an adhesive tape base material, a floor material and the like.

The polyurethane urea foam sheet of the present invention is soluble in an organic solvent such as dimethylformamide or tetrahydrofuran used when measuring the weight average molecular weight by a liquid chromatography method. It is possible to determine the weight average molecular weight. On the other hand, polyurethane urea foamed sheets obtained under various conditions which are conventionally considered to be preferable are generally insoluble in organic solvents such as dimethylformamide, and therefore, in liquid chromatography, the weight average molecular weight may be measured. Can not. For this reason, in the conventional polyurethane urea foam sheet, the weight average molecular weight measured by the liquid chromatography method was not paid attention at all (or rather, it was not possible to pay attention). Without being bound by the conditions that are said to be more suitable, when a number of polyurethane urea foam sheets were trial-produced, it was found that some polyurethane urea foam sheets were soluble in dimethylformamide and the like, and among them, liquid Those having a weight average molecular weight in the range of 200,000 to 500,000 measured by a chromatographic method were found to be excellent in flexibility and low-temperature properties. In the present invention, the weight average molecular weight is represented by a value in terms of polystyrene, but it cannot be used as a standard substance because polyurethane, which should be a standard substance, is insoluble in dimethylformamide or the like. Therefore, when measuring the weight average molecular weight of a solvent-soluble polymer by a liquid chromatography method, polystyrene used as a standard substance is adopted as a standard substance.

The polyurethane urea in the polyurethane urea foam sheet of the present invention is partially crosslinked, but has a weight average molecular weight in the range of 200,000 to 500,000 as measured by the liquid chromatography method described above. Polyurethane urea foam sheet with excellent low temperature properties
It was found to have a clear glass transition point. On the other hand, the polyurethane urea foam sheet obtained under various conditions which are conventionally considered to be preferable does not necessarily have a glass transition point, but rather, generally does not have a clear glass transition point. .

As described above, the polyurethane urea foam sheet of the present invention focuses on the weight-average molecular weight measured by the liquid chromatography method, which was not considered in the prior art, and the value is 200,000 to 500,000, more preferably, 250,000 ~
Since it has the properties of being at 450,000 and having a clear glass transition point, it has excellent flexibility and low-temperature properties, and synthetic leather using this polyurethane foam sheet is a conventional leather. It has a texture comparable to synthetic leather and artificial leather obtained by the wet method.

The weight average molecular weight specified in the present invention is expressed in terms of polystyrene, and is not an accurate numerical value of the weight average molecular weight of the polyurethane urea. In specifying a polyurethane urea foam sheet having excellent properties and low-temperature properties, the value of the weight average molecular weight in terms of polystyrene obtained as described above is sufficient.

The thickness of the polyurethane urea foam sheet of the present invention is limited to 0.2 to 1.0 mm. This is because in the step of reacting and solidifying the coating liquid for obtaining the polyurethane urea foam sheet of the present invention in a humidified and heated atmosphere, supply of water to the coating liquid is indispensable. That is, in the same manner as the method for obtaining the polyurethane urea foam sheet of the present invention, even if an attempt is made to obtain a polyurethane urea foam sheet having an extremely large thickness, uniform water is not supplied to the coated coating solution, and uniform water is not supplied. It does not become a foamed state. On the other hand, even if an attempt is made to obtain a polyurethane urea foam sheet having an extremely small thickness, drying of the solvent in the coated coating liquid is prioritized, and the foaming state is still not good. Therefore, in order to obtain a polyurethane urea foam sheet in a uniform foamed state in the present invention, the thickness is 0.2 to 1.0 mm, preferably 0.25 to 1.0 mm.
It is necessary to make it 0.7 mm.

The polyurethane urea foam sheet of the present invention has a texture comparable to synthetic leather or artificial leather obtained by a wet method by laminating with a fiber base material using an appropriate adhesive, and has flexibility and flexibility. Synthetic leather having excellent low-temperature properties can be obtained.

As the fiber base material, any fiber base material which has been conventionally used as a synthetic leather fiber base material can be used. Specifically, polyester,
Polyamide, polyacrylonitrile, polyolefin,
Synthetic fibers such as polyvinyl alcohol; natural fibers such as cotton and hemp; regenerated fibers such as rayon, swoof, and acetate; alone or a blend thereof, or at least one component dissolved or removed from the sea-island structure, Woven fabrics, knitted fabrics, nonwoven fabrics, and the like are made of multicomponent fibers or the like modified into ultrafine fibers by splitting bicomponent fibers having a tangerine-type structure in a sheath or alternating arrangement. Of course, the fiber substrate may be brushed on one or both sides.

As the adhesive used for laminating the polyurethane urea foam sheet and the fiber base material, there can be used a two-part polyurethane adhesive, a moisture-curable polyurethane adhesive, etc. which have been generally used. From the viewpoint of excellent initial adhesive strength after lamination, a two-pack polyurethane adhesive is preferred.

The above-mentioned synthetic leather has a polyurethane urea foam layer (a layer formed by laminating a polyurethane urea foam sheet) on the surface thereof, similarly to the conventional synthetic leather.
A skin layer mainly composed of polyurethane may be laminated.

The skin layer mainly composed of polyurethane is made of polybutylene adipate, polytetramethylene ether glycol, polycarbonate, polycaprolactone, poly (3-methylpentanediol adipate), poly (β-methyl) having a molecular weight of about 1,000 to 2,000. One or more long-chain glycols selected from long-chain glycols such as valerolactone) and aliphatic diisocyanates such as hexamethylene diisocyanate; At least one diisocyanate selected from aromatic diisocyanates such as' -diphenylmethane diisocyanate;
-One or more short-chain glycols selected from butanediol, ethylene glycol, 3-methylpentanediol, nonanediol and the like, or isophoronediamine, 4,4 '
-Bicyclohexyl methanediamine, xylylenediamine, polyurethane elastomer obtained by reacting at least one short-chain diamine selected from hydrazine, methanol, ethanol, isopropyl alcohol, butanol, toluene, xylene, methyl ethyl ketone, methyl-n- Propyl ketone, methyl isobutyl ketone, diethyl ketone, tetrahydrofuran, methyl cellosolve,
Dissolved in a solvent such as butyl cellosolve, cellosolve acetate, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, dioxane, cyclohexane, etc., and coloring agent, antioxidant, light stabilizer, antistatic agent, flame retardant, A polyurethane elastomer solution obtained by adding various additives such as a natural powder and a filler was applied to a release paper or the like by appropriate means such as a doctor knife coater, and dried and solidified. Things. The skin layer is not limited to a single layer, but may be a multilayer of two or more layers.

In this case, if a layer made of polyurethane having a yield value is provided as the outermost layer, a synthetic leather with extremely good wrinkles can be obtained. Polyurethanes with a yield value of 5
At a small elongation of about 10% to about 10%, it rapidly crystallizes and once exhibits the maximum point of tensile stress, and when it elongates further, this crystal structure is destroyed and the stress increases again when further elongation is continued. At the break point. In the case where the skin layer is formed by using a polyurethane exhibiting such a behavior, the stress is relaxed when an elongation (deformation) above a yield point (a maximum point of the initial tensile stress) or more is given in a kneading process or the like. However, due to the existence of the yield value, the material cannot be returned to the original state, but exists as a residual strain, and it is possible to obtain a natural leather-like wrinkled synthetic leather which is rich in gloss change. . Such behavior is particularly characteristic of polyurethane urea obtained using a non-yellowing type diisocyanate and a short-chain diamine, but even when a yellowing type diisocyanate is used, such behavior is observed. It is possible to obtain the indicated polyurethane.

When a polyurethane layer obtained by using silicone diol as a reaction component is provided as the outermost layer, the coefficient of friction on the surface is reduced, so that synthetic leather having excellent wear resistance can be obtained.

Regarding the laminating method of the skin layer and the polyurethane urea foam layer, each of them is manufactured separately, and these are laminated by using an adhesive such as the above-mentioned polyurethane-based adhesive. The above-mentioned coating solution containing a urethane prepolymer is coated on the skin layer obtained as described above, and the coating solution is reacted and solidified in a humidified, heated atmosphere, or the like.

The synthetic leather obtained as described above can be subjected to a surface treatment for gloss adjustment or the like, if necessary, as in the case of the conventional synthetic leather, and a printed pattern can be formed. Can also. In particular, in the case of the synthetic leather having the polyurethane urea foam layer of the present invention formed thereon, using a high-pressure jet dyeing machine, a drum dyeing machine, a wins dyeing machine, etc.
When rubbing is performed in hot water at a temperature of at least 90 ° C. (90 to 130 ° C.), the material is softened without deteriorating its physical properties, and suitable wrinkles are formed to obtain a more favorable texture. In the kneading process, it is desirable to add a softening agent in hot water in order to prevent abrasion on the surface of the synthetic leather, which is generated by contact with a processing equipment wall, a guide roll, a rotating reel, or the like. .

The polyurethane urea foam sheet of the present invention can be suitably used for synthetic leather as described above. However, the use is not limited to synthetic leather, but may be, for example, a wooden board, if necessary. Synthetic resin sheet, carpet,
Alternatively, the polyurethane urea foam sheet of the present invention may be laminated on the back surface of a surface material such as a laminated product to provide a soundproof flooring material, or at least one surface of the polyurethane urea foam sheet may be appropriately coated with a pressure-sensitive adhesive (adhesive). ) A layer may be formed to form an adhesive tape.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of various conditions required for obtaining the polyurethane urea foam sheet of the present invention will be described below.

The glycol for obtaining the urethane prepolymer can be roughly classified into a long chain glycol and a short chain glycol. In the present invention, a glycol mixture obtained by mixing a long chain glycol and a short chain glycol is used. It is desirable.

Examples of long chain glycols include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxypropylene / oxymethylene glycol, polyethylene glycol adipate, polybutylene glycol adipate,
A long-chain glycol selected from polyneopentyl glycol adipate, polybutylene / hexylene glycol adipate, polycaprolactone, poly-3-methylpentanediol adipate, poly-β-methylvalerolactone, dimer acid diol, or a mixture thereof is preferable. is there. The molecular weight of these long-chain glycols is preferably from 1,000 to 3,000, particularly preferably from 1,000 to 2,000.

As the short-chain glycol, ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, propylene glycol,
Dipropylene glycol, 3-methylpentanediol, 3,3-dimethyl-1,3-propanediol, nonanediol, 2,4-diethyl-1,5-pentanediol, 3,3-dimethylolheptane, 2-ethyl −
A short-chain diol selected from 1,6-hexanediol and 2-methyl-1,3-propanediol, or a mixture thereof is preferred. The above-mentioned short-chain glycol has a molecular weight of 300 or less, does not contain halogen, and has a distance between carbon atoms to which two hydroxyl groups are bonded.
_{Points to 9} or less.

The number average molecular weight of the above-mentioned glycol mixture comprising a long-chain glycol and a short-chain glycol is from 700 to 1
500 is preferable, and it is particularly desirable to be in the range of 800 to 1300. If the number average molecular weight of the glycol mixture is too small, the resulting polyurethane foam sheet will have a sharp change in hardness, even at a temperature near room temperature, for synthetic leather, for adhesive tape bases, and for flooring. It becomes inappropriate.
On the other hand, if the number average molecular weight of the glycol mixture is too large, the resulting polyurethane urea foam sheet will have a low elongation at break, which is also unsuitable for synthetic leather.

The above glycol mixture is reacted with diisocyanate to form a urethane prepolymer. In order to obtain the polyurethane urea foam sheet specified in the present invention, it is preferable to use 4,4′-diphenylmethane diisocyanate as the diisocyanate. 2,4 which are the same aromatic diisocyanate compounds
When / 2,6-toluene diisocyanate is used, not only does the reaction rate become slow, but it is difficult to obtain a polyurethane urea foam sheet having desired physical properties. In addition, when an aliphatic diisocyanate is used, a product having good light resistance can be obtained, but the reactivity is poor.

The glycol mixture and the diisocyanate are
Although it is allowed to react in a solvent, in order to obtain the polyurethane urea foam sheet specified in the present invention, a nonpolar solvent such as cyclohexane, n-hexane, toluene, xylene, industrial gasoline, rubber It is desirable to use a solvent such as a volatile oil or a mixed solvent thereof, among which toluene and xylene are preferred.

In order to stably obtain the polyurethane urea foam sheet having the physical properties specified in the present invention, the amount of the solvent is an important factor. If the amount of the solvent is too small, the reaction rate will be too fast, and the resulting urethane prepolymer will have a molecular weight ranging from extremely small to infinite, and the polyurethane urea foam sheet having the physical properties specified in the present invention. When the amount of the solvent cannot be obtained stably and the amount of the solvent is too large, the viscosity of the urethane prepolymer solution decreases, and the carbon dioxide generated when the coating solution containing the urethane prepolymer is reacted and solidified cannot be retained. Therefore, a polyurethane urea foam sheet in a desired foam state cannot be obtained. If no solvent is used, not only is the viscosity high and difficult to handle, but also
The reaction time is also significantly increased, so that the usable time after mixing becomes extremely short. Moreover, the resulting polyurethane urea foam sheet has coarse cells and poor surface smoothness, and the polyurethane urea has an infinite molecular weight and cannot be produced with good reproducibility as a uniform polyurethane urea sheet. In order to stably obtain the polyurethane urea foam sheet having the physical properties specified in the present invention, the amount of the solvent is desirably 3 to 15% by weight in the urethane prepolymer solution.

According to the knowledge of the present inventor, it has been found that the preferable range of the amount of the solvent is also affected by the number average molecular weight of the glycol mixture used. For example, the number average molecular weight of the glycol mixture is 700 to 100.
When the amount is relatively small, such as about 0, the amount of the solvent is particularly preferably 10 to 15% by weight in the urethane prepolymer, and the number average molecular weight of the glycol mixture is relatively small, such as about 1,000 to 1,500. In such a case, the amount of the solvent is desirably about 3 to 10% by weight of the urethane prepolymer.

Further, it has been found that the amount of the above-mentioned solvent affects the molecular weight distribution of the obtained polyurethaneurea regardless of the number average molecular weight of the glycol mixture.
The molecular weight distribution of the polyurethane urea obtained with a large amount of the solvent is narrow, and the molecular weight distribution of the polyurethane urea obtained with a small amount of the solvent tends to be wide, but in the polyurethane urea foam sheet having the physical properties specified in the present invention, The degree of dispersion (weight average molecular weight / number average molecular weight) serving as an index of the molecular weight distribution of polyurethane urea is about 4 to 8. However, as described above, since the value of the weight average molecular weight in the polyurethane urea foam sheet of the present invention is a value converted into polystyrene, the above-mentioned dispersity is not an absolute value, but is used for relative comparison. It is a numerical value.

In order to stably obtain the polyurethane urea foam sheet having the physical properties specified in the present invention, the molecular weight distribution is preferably as narrow as possible. That is, it is preferable that the amount of the solvent is as large as possible. However, if the amount of the solvent is too large, another problem as described above occurs, so that it is desirable to determine the amount of the solvent so that the amount of the solvent is as large as possible within a range where such a problem does not occur. is there.

As a method for synthesizing the urethane prepolymer, a method of continuously adding a hot-dissolved diisocyanate to a glycol mixture and a solvent in a reaction vessel, a method of charging a glycol mixture, a diisocyanate and a solvent all at once, For example, a method of gradually heating while stirring is used. However, regardless of which method is adopted,
It is necessary that the inside of the reaction vessel for synthesizing the urethane prepolymer be replaced with dry air, carbon dioxide or nitrogen gas.

The urethane prepolymer obtained as described above has an isocyanate group at the terminal. In order to obtain the polyurethane urea foam sheet having the physical properties specified in the present invention, the content of the isocyanate group must be 4. 0 to
It is desirable to adjust the reaction conditions and the like so as to be 5.0% by weight. If the content of the isocyanate group is too low, the desired foamed state is not obtained, and if the content of the isocyanate group is too high, the urea bond increases, and the texture becomes hard, which is unsuitable for synthetic leather and the like. Become. Further, by setting the content of the isocyanate group in the above range, the polyurethane urea foam sheet having a certain molecular weight can be obtained by appropriately partially cross-linking.

The viscosity of the urethane prepolymer solution obtained as described above is 2,000 to 10,000 cP / 2
It is desirable that the temperature be 5 ° C. If the viscosity of the urethane prepolymer solution is too low, it is possible to obtain a stable polyurethane urea foam sheet because air forcedly mixed so as to become a nucleus of foam escapes at the time of coating or the like as described later. If the viscosity is too high,
The leveling property after coating deteriorates, and a polyurethane urea foam sheet having a smooth surface cannot be obtained.

A crosslinking agent and a catalyst are added to the urethane prepolymer solution obtained as described above.

In order to obtain a polyurethane urea foam sheet having the physical properties specified in the present invention, the crosslinking agent is
It is preferable to use a trifunctional polyoxypropylene or the like having a molecular weight of 3,000 to 8,000 and having a primary hydroxyl group with high reactivity at the terminal. Glycerin,
Polyfunctional (2.7 to 3.0 functional groups) hydroxy compounds such as trimethylolpropane and castor oil are added to ethylene glycol, diethylene glycol, dipropylene glycol, 3-methylpentanediol, and 2,4-diethyl-
Short-chain glycols such as 1,5-pentanediol and 3,3-dimethylolheptane and adipates or β
Those to which -methylvalerolactone or the like is added are also suitable.

In order for the above-mentioned crosslinking agent to have a primary hydroxyl group, a secondary hydroxyl group in the molecule of polyoxypropylene is
Means such as addition of ethylene oxide are employed, and by using such a cross-linking agent having a primary hydroxyl group at a terminal, a polyurethane urea foam sheet having high elongation and high flexibility can be obtained. On the other hand, when a cross-linking agent having a secondary hydroxyl group at the end is used, when the urethane prepolymer is reacted in a humidified and heated atmosphere, it easily reacts and solidifies simply with water as a chain extender. However, the molecular weight does not increase sufficiently, and a polyurethane urea foam sheet with high elongation and high flexibility cannot be obtained. The number of moles of ethylene oxide added to the secondary hydroxyl group of polyoxypropylene is not limited to 1 mole,
For example, when it is desired to impart hydrophilicity to the obtained polyurethane urea foam sheet, it can be achieved by using a crosslinking agent having a large addition mole number of ethylene oxide.

The amount of the crosslinking agent to be added to the urethane prepolymer solution is such that the isocyanate group content in the urethane prepolymer is reduced by 0.3 to 0.7% by weight (that is, the isocyanate group content in the urethane prepolymer). It is desirable to set the amount to 3.3 to 4.7% by weight). If the addition amount of the crosslinking agent is too small, the reaction of the urethane prepolymer simply reacts and solidifies water as a chain extender, so that a polyurethane urea foam sheet having a large elongation and high flexibility can be obtained. On the other hand, if the amount is too large, a sufficiently expanded polyurethane urea foam sheet cannot be obtained.

As the catalyst to be added to the urethane prepolymer solution together with the crosslinking agent, it is desirable to use both a tin compound catalyst and an amine catalyst in combination. As a tin compound-based catalyst, tin octylate, dibutyltin dilaurate,
Organotin compounds such as dibutyltin diacetate, dibutyltin dimaleate, dibutyltin mercaptide, dibutyltin oxide, and tin acetylacetonate can be used. Examples of the amine catalyst include triethylamine, N, N-diethylcyclohexylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylpropane-1,3-propanediamine , N, N,
N ′, N′-tetramethylhexamethylenediamine,
N, N, N ', N ", N" -pentamethyldiethylenetriamine, N, N, N', N ", N" -pentamethyldipropylenetriamine, triethylenediamine, N-methylmorpholine, N-ethylmorpholine And other tertiary amine compounds can be used.

The amount of the above catalyst is 0.1 to 0.5 parts by weight of the tin compound based catalyst based on 100 parts by weight of the obtained polyurethane urea (total of a prepolymer composed of a glycol mixture and a diisocyanate and a crosslinking agent). Parts, particularly preferably 0.15 to 0.4 parts by weight,
The amount is preferably 1 to 0.3 part by weight, particularly preferably 0.03 to 0.1 part by weight. The weight ratio of the tin compound catalyst to the amine catalyst to be added is desirably about 1: 0.1 to 1: 1.

In the above urethane prepolymer solution,
It is desirable to add a foam stabilizer and a moisture absorption promoter. As the foam stabilizer, a silicone foam stabilizer used for the production of a flexible polyurethane foam such as a block copolymer of polydimethylsiloxane / polyoxypropylene / polyoxyethylene can be used. It is about 1.0 to 3.0% by weight based on urea.
Also, as a moisture absorption accelerator, is generally used,
Polyoxyethylene ether glycol having a molecular weight of about 500 to 5000, polyoxyethylene polyoxypropylene ether glycol of a polyoxyethylene glycol type at the end, and the like can be used. The amount of the moisture-absorption promoter added is 0.5 to 0.5% based on the obtained polyurethane urea.
It is about 1.5% by weight.

In the above urethane prepolymer solution,
To prevent oxidation of the prepolymer, 2,6-di-t
-Butyl-p-cresol, bisphenol A, 4,
4'-thiobis (6-t-butyl-3-methylphenol), 2,2'-methylenebis (4-methyl-6-t-
Butylphenol), triethylene glycol-bis-
3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate, 1,6-hexanediol-
It is desirable to add a hindered phenolic antioxidant such as bis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate. This hindered phenolic antioxidant is not limited to the one after the synthesis of the urethane prepolymer, and may be added in advance to the reaction solution before the synthesis of the prepolymer. Further, the amount of the hindered phenolic antioxidant added is about 0.5 to 1.5% by weight based on the obtained polyurethane urea.

In the above urethane prepolymer solution,
Further, if necessary, a coloring agent such as a pigment, an ultraviolet absorber,
Various additives such as a fungicide, a light stabilizer, a fragrance, a flame retardant, and a leveling agent can be added.

The urethane prepolymer solution obtained by adding a crosslinking agent, a catalyst, and the like obtained as described above is stirred by an appropriate mixer so that air is mixed, to obtain a coating solution. Since the temperature of the urethane prepolymer solution increases due to the effect of shearing force during stirring or the like, the solidification reaction proceeds before coating or even during the coating operation, and the viscosity increases. Therefore, it is necessary to keep the liquid temperature of the prepolymer solution at a low temperature (specifically, about 20 to 25 ° C.) during the stirring operation and the coating operation.

As means for keeping the coating solution containing a crosslinking agent or the like at a low temperature during the coating operation, a method in which the entire working environment is kept at a low temperature or a method in which this urethane prepolymer solution is brought into contact with a heat exchanger is used. The most common. As the heat exchanger, a plate-shaped heat exchanger having a large area, a coiled-tube heat exchanger, or the like can be used, and an appropriate heat exchanger may be selected according to the coating equipment to be used.

In order to obtain the polyurethane urea foam sheet of the present invention, it is necessary to mix air serving as a foam nucleus into the urethane prepolymer solution to which a crosslinking agent or the like has been added as described above. Preferably, the air to be mixed into the urethane prepolymer solution has a humidity of 30 to 95.
%, Air having a temperature of 10 to 40 ° C. In addition, the mixing ratio of this air, with respect to the urethane prepolymer solution,
It is desirable that the volume ratio be about 0.3 to 1.5%. If the mixing ratio of air is too small, a sufficient foaming state cannot be obtained,
If the mixing ratio of air is too large, a fine foamed structure cannot be obtained.

The urethane prepolymer solution (coating solution) containing a crosslinking agent or the like containing a predetermined amount of air is coated on, for example, release paper or the like by a suitable means such as a doctor knife coater, and humidified. The polyurethane urea foamed sheet of the present invention is reacted and solidified in a heated atmosphere to obtain the polyurethane urea foam sheet of the present invention.

The heating conditions for the reaction and solidification of the coating solution are 90 to 150 ° C., preferably 1 to 150 ° C.
It is desirable to be in the range of 05 to 130 ° C. If the temperature is too high, bumping of the solvent occurs, and a polyurethane urea foam sheet having a smooth surface cannot be obtained. If the temperature is too low, the rate of foaming and solidification reaction becomes too slow, which is not preferable as a production condition.

As the humidifying conditions for reacting and solidifying the coating solution, the absolute humidity cannot be measured accurately because of the high temperature, but the chemical equivalent required for the reaction of isocyanate groups in the coating solution is required. It is necessary that the above amount of water is always present. As specific means for achieving such humidification conditions, blowing of high-pressure steam or supply of ultrafine water droplets by ultrasonic waves is effective.

[0052]

EXAMPLES Specific examples will be shown below, but the present invention is not limited to the following examples.

Example 1 873.1 g of 4,4'-diphenylmethane diisocyanate, 348.1 g of toluene
A mixture of 500 g of polyoxypropylene glycol having a molecular weight of 1,000 (diol type, the same applies hereinafter) and 1,000 g of polyoxypropylene glycol having a molecular weight of 2,000 was added to a solution of 45 ° C. with stirring under a nitrogen atmosphere. After raising the temperature to 0 ° C. and reacting for 4 hours, 134.18 g of dipropylene glycol,
A solution composed of 100 g of toluene was added dropwise over 30 minutes, and the mixture was stirred at 85 ° C. for 1 hour to react. After cooling to 25 ° C., a urethane prepolymer solution having a viscosity of 7500 cP / 25 ° C. (urethane prepolymer solution) A-1) was obtained. The obtained urethane prepolymer is 4.
It had 95% by weight of isocyanate groups.

Then, 480 g of a propylene oxide / ethylene oxide adduct of glycerin (polyoxyethylene glycol / polyoxypropylene glycol = 2/8) having a hydroxyl value of 24, and an ethylene oxide / propylene oxide-added polydimethylsiloxane-based foam stabilizer were used. 29.9 g, 29.9 g of a polyethylene glycol / polypropylene glycol copolymer having a hydroxyl value of 56.1 (polyethylene glycol / polypropylene glycol = 2/8), 7.2 g of tin octylate, N, N, N ′,
N ″, N ″ -pentamethyldiethylenetriamine
8 g, and mixed solution containing a crosslinking agent (crosslinking agent solution B-
1).

The urethane prepolymer solution A-1 and the crosslinking agent solution B-1 were mixed at a mixing ratio of 100 / 18.6, and 1
Stir at a speed of 500 rpm, temperature 25 ° C, humidity 65
% Air was mixed at 1.0% by volume.

The resulting mixture (coating solution) was coated on a 75 μm-thick polyester film coated with a silicone resin and provided with releasability so as to have a coating thickness of 0.35 mm. The mixture was reacted in an oven with a humidifier at 115 ° C. for 3 minutes to obtain a polyurethane urea foam sheet having a thickness of 0.55 mm. The obtained polyurethane urea foam sheet had a clear glass transition point and was excellent in flexibility and low-temperature properties.

Further, the obtained polyurethane urea foam sheet was dissolved in dimethylformamide to make a 0.1% solution, and the weight average molecular weight of the polyurethane urea was measured by a liquid chromatography method. The number average molecular weight was 60,000, and the degree of dispersion was 6.35.

Example 2 A solution containing 990 g of 4,4'-diphenylmethane diisocyanate, 255 g of toluene and 127.7 g of xylene at 45 ° C. and having a molecular weight of 1
1300 g of 000 polyoxypropylene glycol
And a mixture comprising 1300 g of polyoxypropylene glycol having a molecular weight of 2,000 was added with stirring, the mixture was heated to 80 ° C. in a nitrogen atmosphere and reacted for 4 hours.
After cooling to 5 ° C., a urethane prepolymer solution having a viscosity of 4500 cP / 25 ° C. (urethane prepolymer solution A
-2). The resulting urethane prepolymer had 4.68% by weight of isocyanate groups.

Next, 237.1 g of a propylene oxide / ethylene oxide adduct of glycerin having a hydroxyl value of 24 (polyoxyethylene glycol / polyoxypropylene glycol = 2/8) was prepared.
38.3 g of a propylene oxide-added polydimethylsiloxane-based foam stabilizer, a polyethylene glycol / polypropylene glycol copolymer having a hydroxyl value of 56.1 (polyethylene glycol / polypropylene glycol = 2 /
8) 38.3 g, tin octylate 9.2 g, N, N,
2.3 g of N ′, N′-tetramethylhexamethylenediamine was mixed to obtain a mixed solution containing a cross-linking agent (referred to as a cross-linking agent liquid B-2).

The urethane prepolymer solution A-2 and the crosslinking agent solution B-2 were mixed at a mixing ratio of 100 / 8.2, and
Stir at a speed of 00rpm, temperature 25 ℃, humidity 65%
Was mixed in a volume ratio of 1.0%.

The obtained mixed solution was coated on a 75 μm-thick polyester film coated with a silicone resin to give a releasability, and the coating thickness was 0.35 m.
m, and reacted in an oven with a humidifier at 120 ° C. for 3 minutes to obtain a thickness of 0.54 mm.
A polyurethane urea foam sheet was obtained. The obtained polyurethane urea foam sheet had a clear glass transition point and was excellent in flexibility and low-temperature properties.

The obtained polyurethane urea foam sheet was dissolved in dimethylformamide to form a 0.1% solution, and the weight average molecular weight of the polyurethane urea was measured by liquid chromatography. The number average molecular weight was 550,000 and the degree of dispersion was 5.6.

Comparative Example 1 Dipropylene glycol 13
By reacting 4.18 g with 873.1 g of 4,4'-diphenylmethane diisocyanate, a urethane prepolymer having an isocyanate group content of about 21% by weight was obtained (hereinafter referred to as urethane prepolymer A-3). In addition, this urethane prepolymer A-3 did not contain a solvent, but was a viscous liquid.

Next, 500 g of a polyoxypropylene glycol having a molecular weight of 1000, 1000 g of a polyoxypropylene glycol having a molecular weight of 2,000, and a hydroxyl value of 2
480 g of a propylene oxide / ethylene oxide adduct of glycerin (polyoxyethylene glycol / polyoxypropylene glycol = 2/8) of No. 4, 29.9 g of an ethylene oxide / propylene oxide added polydimethylsiloxane-based foam stabilizer, and a hydroxyl value of 56. 29.9 g of the polyethylene glycol / polypropylene glycol copolymer (polyethylene glycol / polypropylene glycol = 2/8) of No. 1 and 7.2 of tin octylate
g, N, N, N ', N ", N" -pentamethyldiethylenetriamine (1.8 g) were mixed to obtain a mixed solution containing a crosslinking agent (referred to as a crosslinking agent solution B-3).

Urethane prepolymer A-3 and crosslinking agent liquid B
-3 at a mixing ratio of 100 / 203.4,
Stir at a speed of 00rpm, temperature 25 ℃, humidity 65%
Was mixed in a volume ratio of 1.0%.

The obtained mixed solution was coated on a 75 μm-thick polyester film coated with a silicone resin to give a releasability, and the coating thickness was 0.35 m.
m, and reacted at 120 ° C. for 3 minutes in an oven with a humidifier to obtain a thickness of 0.80 mm.
A polyurethane urea foam sheet was obtained.

In Comparative Example 1, since no solvent was contained, the reaction rate was extremely high despite the presence of a large number of secondary hydroxyl groups having low reactivity, and the time from mixing and stirring to coating was only about 2 minutes. In addition, the leveling property was remarkably poor because the viscosity was significantly increased even during coating, and the obtained polyurethane urea foam sheet had severe irregularities. In addition, the cells were extremely coarse and non-uniform.

Further, for the obtained polyurethane urea foam sheet, it was attempted to measure the weight average molecular weight of polyurethane urea in the same manner as in Example 1, but it was impossible (the measured value was infinite). T).

[Comparative Example 2] 4,4'-
A polyurethane urea foamed sheet was obtained in the same manner as in Example 1 except that the amount of toluene mixed with 873.1 g of diphenylmethane diisocyanate was 696.2 g (provided that the viscosity of the urethane prepolymer solution was 1200 c
P / 25 ° C.).

When the weight average molecular weight of the obtained polyurethane urea foam sheet was measured in the same manner as in Example 1, it was 196,000 in terms of polystyrene, the number average molecular weight was 53,000, and the dispersity was 3 0.7. Also,
The polyurethane urea foam sheet obtained in Comparative Example 2 was inferior in flexibility and low-temperature properties, and extremely poor in foaming state.

Example 3 475 g of polyoxypropylene glycol having a molecular weight of 1000 and 95 parts of poly (3-methylpentanediol adipate) having a molecular weight of 2,000
0 g, 508 g of 4,4′-diphenylmethane diisocyanate and 271 g of toluene were mixed and reacted to obtain a urethane prepolymer solution having a viscosity of 6100 cP / 25 ° C. (hereinafter referred to as urethane prepolymer solution A-4). The resulting urethane prepolymer had an isocyanate group content of 4.65% by weight.

Then, 230 g of a propylene oxide / ethylene oxide adduct of glycerin (polyoxyethylene glycol / polyoxypropylene glycol = 2/8) having a hydroxyl value of 24, and an ethylene oxide / propylene oxide-added polydimethylsiloxane-based foam stabilizer were used. 22 g, 4.5 g of dibutyltin dilaurate, and 2.3 g of N-methylmorpholine were mixed to obtain a mixed solution containing a crosslinking agent (referred to as a crosslinking agent solution B-4).

The urethane prepolymer solution A-4 and the crosslinking agent solution B-4 were mixed at a mixing ratio of 100 / 11.8,
Stir at a speed of 500 rpm, temperature 25 ° C, humidity 65
% Air was mixed at 1.0% by volume.

The obtained mixed solution was coated on a 75 μm-thick polyester film coated with a silicone resin to give releasability, and the coating thickness was 0.35 m.
m, and reacted in an oven with a humidifier at 110 ° C. for 3 minutes to obtain a polyurethane urea foam sheet having an extremely smooth surface.

In Example 3, the thickness of the obtained polyurethane urea foam sheet can be arbitrarily controlled between 0.3 and 0.8 mm, and the density thereof is 0.75 to 0. At 0.46 g / cm ³ , the density was lower as the thickness increased. Furthermore, the polyurethane urea foam sheet obtained in Example 3 is:
It had a clear glass transition point, was excellent in flexibility and low-temperature properties, and was extremely excellent in elongation in the range of about 450 to 500%.

The polyurethane urea foam sheet thus obtained was dissolved in dimethylformamide to form a 0.1% solution, and the weight average molecular weight of the polyurethane urea was measured by liquid chromatography. The number average molecular weight of the polyurethane urea was 56,000 and the degree of dispersion was 7.5.

Comparative Example 3 3900 g of polyoxypropylene glycol having a molecular weight of 2,000, 1201 g of 4,4'-diphenylmethane diisocyanate and 276 g of toluene were mixed and reacted, and the viscosity was 3,800 cP / 2.
A urethane prepolymer solution at 5 ° C. (referred to as urethane prepolymer solution A-5) was obtained. The resulting urethane prepolymer had an isocyanate group content of 4.7% by weight.

Next, 425 g of a propylene oxide / ethylene oxide adduct of glycerin (polyoxyethylene glycol / polyoxypropylene glycol = 2/8) having a hydroxyl value of 24, and an ethylene oxide / propylene oxide-added polydimethylsiloxane-based foam stabilizer were used. 55 g, 13.5 g of dibutyltin dilaurate, N-
4.5 g of methyl morpholine was mixed to obtain a mixed solution containing a cross-linking agent (referred to as cross-linking agent liquid B-5).

The urethane prepolymer solution A-5 and the crosslinking agent solution B-5 were mixed at a mixing ratio of 100 / 9.3, and
Stir at a speed of 00rpm, temperature 25 ℃, humidity 65%
Was mixed in a volume ratio of 1.0%.

The obtained mixed solution was coated on a 75 μm-thick polyester film coated with a silicone resin to give a releasability, and the coating thickness was 0.35 m.
m, and reacted in an oven with a humidifier at 110 ° C. for 3 minutes to obtain a polyurethane urea foam sheet.

The polyurethane urea foam sheet obtained in Comparative Example 3 is inferior in flexibility and low-temperature properties,
The elongation percentage was as small as about 180%.

The polyurethane urea foam sheet obtained was measured for weight average molecular weight in the same manner as in Example 1, but was impossible.

Comparative Example 4 Urethane Prepolymer Solution A
-1 and the crosslinking agent solution B-1 were mixed at a mixing ratio of 100 / 18.6, and immediately defoamed under vacuum to obtain a mixed solution. This mixed solution is coated on a 75 μm-thick polyester film coated with a silicone resin to give releasability so as to have a coating thickness of 0.35 mm, and then heated to 115 ° C. in an oven with a humidifier. 3
After reacting for a minute, almost no foaming occurred.

Example 4 Polycaprolactone (Placcel L-2010; trade name, manufactured by Daicel Chemical Industries, Ltd.) 1
860 g, 549 g of 4,4′-diphenylmethane diisocyanate and 376 g of toluene were mixed and reacted,
A urethane prepolymer solution (referred to as urethane prepolymer solution A-6) was obtained. The obtained urethane prepolymer had an isocyanate group content of 4.34% by weight.

Next, 100.4 g of a β-valerolactone adduct of glycerin (Kuraray Co., Ltd., molecular weight 3000) was prepared.
25.1 g of an ethylene oxide / propylene oxide-added polydimethylsiloxane-based foam stabilizer, 5.1 g of tin octylate, and 4.5 g of N-ethylmorpholine were mixed, and a mixed solution containing a crosslinking agent (crosslinking agent solution B) −6).

The urethane prepolymer solution A-4 and the crosslinking agent solution B-4 were mixed at a mixing ratio of 100 / 4.7, and
Stir at a speed of 00rpm, temperature 25 ℃, humidity 65%
Was mixed in a volume ratio of 1.0%.

The obtained mixed solution was coated on a 75 μm-thick polyester film coated with a silicone resin to give a releasability, and the coating thickness was 0.25 m.
m, and reacted in an oven with a humidifier at 115 ° C. for 3 minutes to obtain a polyurethane urea foam sheet.

The resulting polyurethane urea foam sheet had a tensile strength of 12 kgf / cm ² , a breaking elongation of 550%,
It had a density of 0.45 g / cm ³ , a clear glass transition point, and excellent flexibility and low-temperature properties. Further, the obtained polyurethane urea foamed sheet was dissolved in dimethylformamide to form a 0.1% solution, and the weight average molecular weight of the polyurethane urea was measured by liquid chromatography to be 320,000 in terms of polystyrene. The number average molecular weight of urea is 58,000,
The dispersity was 5.5.

[0089]

As described above, the weight average molecular weight measured by the liquid chromatography method is 20 in terms of polystyrene.
In the range of 10,000 to 500,000, and the polyurethane urea foam sheet having a glass transition point, unlike a conventional polyurethane urea foam sheet, there is no disadvantage of inferior low-temperature properties, and also excellent flexibility, It can be suitably used for applications such as synthetic leather, adhesive tape bases, and flooring. In particular, the synthetic leather obtained using the polyurethane urea foam sheet has a texture comparable to synthetic leather and artificial leather obtained by the wet method, in addition to the above effects, and, in a simple manufacturing process, It can be manufactured at low cost.

Claims (1)

(57) [Claims] 1. A coating solution obtained by adding a crosslinking agent and a catalyst to a solution of a urethane prepolymer having an isocyanate group at a terminal obtained by reacting a glycol with a diisocyanate and mixing air containing moisture. A partially crosslinked polyurethane urea foam sheet having a thickness of 0.2 to 1.0 mm obtained by coating, reacting and solidifying in a humidified and heated atmosphere, wherein the polyurethane urea has a weight measured by a liquid chromatography method. Average molecular weight is 200,000 to 5 in terms of polystyrene
A polyurethane urea foam sheet having a glass transition point in a range of 10,000.