JPH0231117B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyurethane composition that can provide a polyurethane composite with excellent performance when used as a coating agent for artificial leather or fabric. Since polyurethane has excellent mechanical strength, abrasion resistance, and flexibility, it has been widely used for artificial leather. In order to obtain a polyurethane that is more suitable for these uses, we need to study the required properties such as light resistance, cold resistance, low temperature flexibility, heat resistance, heat deterioration resistance, color fastness, and polymer solution stability. Many attempts have been made to improve performance, and various methods have been proposed to improve individual performance requirements. However, in all of the previous attempts, the degree of improvement was only a step forward, and even if they were satisfactory with respect to the specific required performance, they ended up significantly deteriorating other required performance. It was a lot of stuff, and I wasn't satisfied with it. Polyurethane is obtained by reacting a polymeric diol with an organic diisocyanate and an active hydrogen compound as a chain extender, but for example, when an aromatic organic diisocyanate is used as the organic diisocyanate, the resulting polyurethane has poor light deterioration resistance. Specifically, it is known that light irradiation causes yellowing and a decrease in strength and elongation. Light deterioration resistance is improved by using an aliphatic or alicyclic organic diisocyanate instead of an aromatic organic diisocyanate. However, even in this case, although it is possible to considerably prevent yellowing due to light irradiation in light deterioration resistance, it is often insufficient to prevent a decrease in strength and elongation due to photodeterioration. Furthermore, polyurethanes using aliphatic or alicyclic organic diisocyanates have drawbacks such as low softening temperature, low tensile stress, too much flexibility, and poor surface abrasion resistance. In order to improve this drawback, a method is generally adopted in which a diamine is used instead of a low-molecular diol as a chain extender, and a urea bond is introduced into the chain to increase intermolecular cohesive force. Furthermore, in order to further increase the improvement effect, a method of increasing the ratio of organic diisocyanate and low molecular weight organic diamine to the polymer diol can also be considered. However, the method of introducing a urea bond using a diamine as a chain extender has a serious drawback on the solution stability of the polyurethane solution. That is, extremely undesirable situations such as the polymer solution becoming thickened or gelatinous during polymerization or during storage after polymerization tend to occur. This thickening and gelation phenomenon is 10 to 20
Even if this phenomenon does not occur much at room temperature of 0.degree. C., it is often noticeable when left at a low temperature around 0.degree. C., which is an extremely important problem. Furthermore, this phenomenon becomes particularly noticeable when the ratio of organic diisocyanate and organic diamine to the polymeric diol is high, or when the ratio of so-called hard segments is high. In addition, one of the advantages of polyurethane using alicyclic organic diisocyanate is that compared to polyurethane using aromatic organic diisocyanate, dimethylformamide (hereinafter abbreviated as DMF), which has a high boiling point, is expensive, and has high toxicity as a solvent, dimethyl In addition to solvents such as sulfoxides, low-toxicity solvents (generally referred to as soft solvents) such as isopropanol/toluene mixed solvents may also be used. However, when using this soft solvent, there is a drawback that thickening and gelation phenomena occur more easily than with DMF or the like. Further, in general, it is an important issue in this industry to further improve the cold resistance of polyurethane elastomers. In other words, even if artificial leather coated with polyurethane elastomer is highly flexible at room temperature, it loses its elasticity and becomes hard under low temperature conditions such as -10°C or -20°C, leading to a decline in various physical properties. This is a trend, and improvement is desired. Cold resistance of polyurethane elastomer,
In order to improve low-temperature flexibility, it is sufficient to lower the glass transition temperature of polymeric diols, and one effective way to do this is to use polymeric diols with relatively large average molecular weights, that is, long chain lengths. It is possible to use it. However, in this case, in order to prevent the polyurethane elastomer from becoming too flexible, it is necessary to increase the amount of hard segments made of organic diamine in the organic diisocyanate and lengthen the chain length. As mentioned above, when the amount of hard segments in the polyurethane elastomer is increased,
Since this method has the disadvantage of poor polymer solution stability, it is difficult to put this method into practical use. Furthermore, polyurethanes using hydrazine as a chain extender are generally known to have excellent light resistance. However, on the other hand, this polyurethane has extremely poor polymer solution stability and inevitably gels during polymerization. It also has undesirable drawbacks such as poor heat resistance, that is, a low heat softening temperature. As a result of intensive research by the present inventors on obtaining a polyurethane composition that has both cold resistance and heat resistance while maintaining many of the above-mentioned required performances, especially light resistance, and also ensures polymer solution stability, We have arrived at the present invention. The present invention is a polyurethane composition in which specific compounds are selected from many well-known compounds and used in specific proportions, and the effects obtained by the present invention are obtained when each raw material is used independently. The results are not entirely predictable. That is, in the present invention, (a) the average molecular weight is from 1200 to
a polymeric diol within the range of 2500, (b) an alicyclic organic diisocyanate in an amount of 2.3 to 4.7 times the mole of the polymeric diol, (c) an alicyclic organic diamine, and (d)
A polyurethane composition comprising a polyurethane synthesized from hydrazine and a solvent for this polyurethane, and under the following conditions (i) to (iv) (i) The alicyclic organic diisocyanate is isophorone diisocyanate or the general formula (However, R ₁ and R ₂ represent a hydrogen atom or a lower alkyl group) or a mixture of both; (ii) the alicyclic organic diamine is isophorone diamine or a diisocyanate compound represented by the general formula (However, R ₃ and R ₄ represent a hydrogen atom or a lower alkyl group) or a mixture of both, and furthermore, in the total amount of alicyclic organic diisocyanate, alicyclic organic diamine and hydrazine. (iii) the ratio of hydrazine to the total amount of hydrazine and alicyclic organic diamine is 0.05 to 0.5 in molar ratio;
(iv) 3 to 70% by weight of the solvent has the general formula R(CH ₂ ) _o OH
(However, in the formula, when R is a hydrogen atom, n is an integer from 0 to 4, and when R is a methoxy group, ethoxy group, or acetoxy group, n
2) and 97 to 30% by weight of a solvent other than an amide-based or sulfoxide-based aprotic polar solvent. This is a polyurethane composition with properties suitable for use as a coating agent. This polyurethane is
Surprisingly, it not only satisfies light resistance, cold resistance, heat resistance, and polymer solution stability, but also improves physical properties such as strength and elongation, surface properties such as water resistance, color fastness, and surface abrasion resistance. It has excellent flexibility in all respects. Each component of the present invention will be specifically explained below. First, the polymer diols used in the polyurethane composition of the present invention include general polymer diols such as polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polyester glycols, polyacetal glycol, polycarbonate glycol, and polybutadiene glycol. Can be mentioned. The polyurethane obtained by the present invention has sufficient resistance to light deterioration and oxidative deterioration for practical use in applications such as artificial leather, but in cases where a polyurethane with even better light resistance and oxidative deterioration resistance is required. In this case, it is particularly preferable to use a diol mainly composed of polyester chains or polycarbonate chains as the polymeric diol. In addition, if it is necessary to improve the dyeability and color fastness of the obtained polyurethane, a diol containing an ethylene oxide structural unit may be used as the polymeric diol, or a diol containing an ethylene oxide structural unit and a diol not containing an ethylene oxide structural unit may be used. It is preferable to use a mixed diol and to adjust the proportion of ethylene oxide structural units in the polymeric diol to 5 to 50% by weight based on the total polymeric diol. In the present invention, it is important that the average molecular weight of the polymeric diol is 1200 to 2500. High molecular weight diols with an average molecular weight of about 1000 are commonly used in the production of polyurethane elastomers, but as contemplated by the present invention,
When trying to obtain a polyurethane elastomer with excellent light resistance, cold resistance, and heat resistance using alicyclic organic diisocyanate, the average molecular weight is 1200.
It is important to use the above polymeric diol and to increase the ratio of diisocyanate to the polymeric diol. When a polymeric diol having an average molecular weight of less than 1200 is used, both cold resistance and heat resistance become insufficient. That is, the resulting elastomer is only an elastomer with a high glass transition temperature, poor flexibility at low temperatures, and a low thermal softening temperature. Even when trying to improve cold resistance and heat resistance by using polymeric diols with an average molecular weight of 1200 or less and varying the ratio of diisocyanate to polymeric diol,
It is difficult to improve both at the same time, and physical properties such as strength and elongation and flexibility at room temperature will also be sacrificed. Furthermore, if a polymer diol with an average molecular weight of 2,500 or more is used to improve both cold resistance and heat resistance, it is necessary to further increase the amount of diisocyanate and low molecular diamine used, which increases the stability of the polymer solution and the strength of polyurethane. This also results in unfavorable physical properties such as elongation. Further, examples of the alicyclic organic diamine used in the present invention include isophorone diamine, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-
Examples include 3,3'-dimethyldicyclohexylmethane and cyclohexylene diamine. In addition, examples of the alicyclic organic diisocyanate used in the present invention include isophorone diisocyanate,
Examples include dicyclohexylmethane-4,4'-diisocyanate, 4,4'-isopropylidene dicyclohexane diisocyanate, and cyclohexylene diisocyanate. When an aliphatic type is used instead of the alicyclic organic diisocyanate or the alicyclic organic diamine, the resulting polyurethane has good cold resistance, heat resistance,
The mechanical properties will be significantly inferior, and if aromatic materials are used, the light deterioration resistance will be significantly inferior. In the present invention, the molar ratio of alicyclic organic diisocyanate to polymeric diol is 2.3 to
Being within the range of 4.7 is an important factor along with the average molecular weight of the polymeric diol. The molar ratio is
If it is smaller than 2.3, the heat resistance will be insufficient, that is, the thermal softening temperature will decrease. Furthermore, the solvent resistance is also significantly poor. Also, the molar ratio is 4.7
If it exceeds this range, it is unfavorable in terms of polymer solution stability, and the flexibility at room temperature is insufficient, making it difficult to withstand use. In addition, in the present invention, when it is necessary to maintain polymer solution stability and to have better heat resistance, cold resistance, and general physical properties such as strength and elongation, and surface strength, isophorone is used as an organic diisocyanate. Diisocyanate or general formula

Using a diisocyanate compound represented by [Formula] (where R ₁ and R ₂ represent a hydrogen atom or a lower alkyl group) or a mixture of both, isophorone diamine or the general formula

[Formula] (However, R ₃ and R ₄ represent a hydrogen atom or a lower alkyl group)
It is preferable to use a diamine compound represented by the following formula or a mixture of both, and to make the ratio of the total amount of isophorone diisocyanate and isophorone diamine in the total amount of organic diisocyanate, organic diamine, and hydrazine to 25 mol % or more. If it is less than 25 mol%, the stability of the polymer solution tends to be somewhat poor. As the diisocyanate compound represented by the above general formula, dicyclohexylmethane-4,
4'-diisocyanate, 3,3'-dimethyl-dicyclohexylmethane-4,4'-diisocyanate, 4,4'-isopropylidene dicyclohexyl diisocyanate, 3,3'-dimethyl-4,4'-
Examples include isopropylidene dicyclohexyl diisocyanate. In addition, examples of the diamine compound represented by the above general formula include 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,
4'-diamino-dicyclohexylmethane, 4,
Examples include 4'-isopropylidene dicyclohexyl diamine, 3,3'-dimethyl-4,4'-isopropylidene dicyclohexyl diamine, and the like. In the present invention, a small amount of an aliphatic or aromatic organic diisocyanate, an organic diamine, or even an organic active hydrogen compound other than the diamine may be substituted. However, as these amounts increase, one of the required performances deteriorates. Further, in the present invention, it is necessary to use hydrazine as a chain extender in order to obtain more excellent light resistance. The amount of hydrazine used is based on the total amount of alicyclic organic diamine and hydrazine.
It ranges from 0.05 to 0.5. The amount of alicyclic organic diamine mentioned here means the amount of these compounds alone. Therefore, when replacing a small amount of alicyclic organic diamine with other active hydrogen compounds, those This value does not include the amount of active hydrogen compounds. If the amount of hydrazine used is less than the above 0.05, the light deterioration resistance and oxidation deterioration resistance of the resulting polyurethane will decrease, resulting in a decrease in strength and elongation. Conversely, if the amount of hydrazine used exceeds the above 0.5, the resulting polyurethane will have a low heat softening temperature and will also have poor polymer solution stability. Note that the hydrazine used in the present invention may be in a hydrated form. A further important factor in the present invention is the solvent constituting the polyurethane composition. Basically, a solvent is used that dissolves the polyurethane. That is, aprotic polar solvents such as dimethylformamide, diethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, N,N-tetramethylurea, hexamethylenephosphoramide, tetramethylsulfone, benzene, Aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, ester solvents such as methyl acetate, ethyl acetate, and butyl acetate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and chlorinated carbons such as trichlene and dichloroethane. Hydrogen solvents, alcohol solvents such as isopropanol, and ether solvents such as tetrahydrofuran and dibutyl ether are used. However, the most important thing to note here is that some of these solvents have the general formula R(CH ₂ ) _o OH (however,
In this formula, when R is a hydrogen atom, n means an integer from 0 to 4, and when R is a methoxy group, ethoxy group, or acetoxy group, n means 2). 3 to 70%, preferably 5 to 60, of one or more selected items
% is an essential condition of the present invention. If the compound represented by the above general formula is not present, or even if it is present, it is less than 3%, the stability of the polymer solution will be poor. We used a polymeric diol with an average molecular weight of 1200 or more, increased the ratio of alicyclic organic diisocyanate to the polymeric diol (inevitably increasing the amount of alicyclic diamine used), and increased the hard segment chain length. In the polyurethane elastomer of the present invention, it has been found that the addition of a compound of the above general formula is particularly significant. When the compound of the above general formula is not added or in a small amount, thickening and gelation phenomena are observed in the polymer solution over time. Although this phenomenon is not noticeable at room temperature (e.g. 10-20°C), at low temperature (e.g. 0°C)
℃), it is often observed that the viscosity clearly increases over time (this is not simply due to the effect of temperature on viscosity). The compound of the above general formula may be added during the polymerization of the polyurethane elastomer, or may be added after the polymerization is complete, that is, after free isocyanate groups are completely eliminated. When thickening during polymerization becomes a problem, it is preferable to add it during polymerization. However, the reaction between the isocyanate group and the compound of the above general formula occurs, even if it is extremely small compared to the diamine used as an extender.
It is desirable that the compound of the above general formula be added in the latter half of the polymerization, since this may cause a decrease in the molecular weight of the polyurethane. If the proportion of the compound of the above general formula exceeds 70%, the viscosity of the polymer solution will become too high or the solubility of the polyurethane will become poor, resulting in cloudiness and phase separation phenomena, which is undesirable. In addition, when polymerizing polyurethane elastomer,
To eliminate residual isocyanate at the end of polymerization,
It is already known to add monoalcohol or to use water as part of the extender, but both of these utilize the reaction between isocyanate groups and alcohol or water, and the amount added is small. . It goes without saying that the purpose of the present invention is completely different from the use of water or monoalcohol. For example, in the present invention, whether or not a small amount of monoamine is added to the target polyurethane elastomer at the final stage of polymerization to completely eliminate residual isocyanate, the stability of the polymer solution due to the addition of the compound of the above general formula The effect on is unchanged. Furthermore, in the present invention, amide solvents such as dimethylformamide and sulfoxide solvents such as dimethyl sulfoxide are avoided due to their high cost and high boiling point, and other solvents such as toluene, tetrahydrofuran, isopropanol, and methyl ethyl ketone are used. This may result in various advantages. When such a solvent is used, at least one compound selected from the compounds of the above general formula accounts for 7 to 70%, especially 10 to 70% of the total solvent.
It is preferable to add it to 60%. Examples of the compound represented by the above general formula include water, methanol, ethanol, n-propanol, n-butanol, methyl cellosolve, ethyl cellosolve, and acetic cellosolve. When a polyurethane solution is used for synthetic leather, the polyurethane concentration in the solution is usually in the range of 3 to 40% by weight, and the composition of the present invention is also preferably a composition in which the polyurethane concentration is in this range. . Next, a typical manufacturing method of the polyurethane composition of the present invention will be explained. First, a polymeric diol and the alicyclic organic diisocyanate in an excess amount relative to the terminal hydroxyl group of the polymeric diol are heated and stirred at 50 to 130° C. under a nitrogen atmosphere to obtain a prepolymer having isocyanate groups at the terminals. The obtained prepolymer is mixed with an amide-based or sulfoxide-based solvent,
Alternatively, it is dissolved in a solvent such as toluene, tetrahydrofuran, isopropanol, methyl ethyl ketone, etc., and chain-extended with hydrazine and alicyclic organic diamine at a temperature around room temperature to obtain a polyurethane solution. Then, the compound represented by the above general formula is added to this polyurethane solution to obtain the composition of the present invention. In addition to the above methods, there are various methods for obtaining the polyurethane composition of the present invention, and the present invention is not limited to the above methods. In the present invention, in order to further improve the dyeability of the obtained polyurethane, compounds containing tertiary nitrogen, such as N-methylaminobispropylamine, N-methyldiethanolamine, N-isobutyldiethanolamine, 1,4-bisamino Propylpiperazine and the like may also be used as part of the chain extender. However, as the amount of these tertiary nitrogen-containing compounds increases, the required performance other than dyeability will decrease, so the amount of tertiary nitrogen-containing compounds should be within 15 mol% of the total amount of chain extender. It is preferable to keep it at a minimum. Furthermore, the polyurethane composition of the present invention may contain antioxidants, ultraviolet absorbers, pigments, dyes, flame retardants, and other various additives and fillers. The polyurethane composition of the present invention can be used as a coating agent for plastics, rubber, glass, etc. in addition to a coating agent for artificial leather and fabrics, and in particular, by dispersing magnetic powder in the polyurethane composition of the present invention, By coating the surface of a polyester film, a magnetic tape with excellent durability and surface strength can be obtained, and by adding a coloring agent, typically a pigment, to the polyurethane composition of the present invention, polyamide, polyolefin, polyester,
Durability can be improved by printing on the surface of a film such as saponified ethylene-vinyl acetate copolymer.
A printed film with excellent surface strength etc. can be obtained. For these magnetic tapes or printed films,
When using the polyurethane composition of the present invention,
The polyurethane constituting the polyurethane composition preferably uses polycarbonate glycol as the polymer diol. The present invention will be specifically explained below using Examples.
All of the raw materials for polyurethane used in the examples are indicated using abbreviations, and the relationships between abbreviations and compounds are as follows.

[Table] Cyanate

[Table] Examples 1 and 2, Comparative Examples 1 and 2 Polyurethane elastomers were produced using the reagents shown in Table 1. That is, a certain amount of polymeric diol and organic diisocyanate was heated at 60 to 100℃ under nitrogen.
Stir and react for 2 to 6 hours. The obtained prepolymer was mixed with toluene/isopropanol (5/
5, weight ratio). Next, after dissolving a predetermined amount of chain extender in toluene, this solution is added to the above-mentioned prepolymer solution, and the mixture is stirred at 30°C under nitrogen for 2 to 5 hours to react. When the reaction is about half way through, methanol is added in a weight ratio of toluene/isopropanol/methanol of 6/4/3. The obtained polyurethane solution is cast onto a glass plate and dried to obtain a dry film with a thickness of about 30 μm. This dry film was subjected to various physical property tests. The results are shown in Table 2.

【table】

[Table] Examples 3 and 4, Comparative Examples 3 and 4 A polyurethane elastomer was obtained in the same manner as in Example 1 using the reagents listed in Table 3. The results are shown in Table 4.

【table】

[Table] Examples 5 to 9, Comparative Examples 5 to 7 PCL with an average molecular weight of 2000 as a polymeric diol,
IPDI as organic diisocyanate, _H12 DAM and hydrazine as chain extenders in a molar ratio of 1.0:
A polyurethane composition was obtained in the same manner as in Example 1, using the solvents listed in Table 5 at a ratio of 4.0:2.0:1.0. The results are shown in Table 5.

【table】

【table】

Claims (1)

[Scope of Claims] 1. (a) A polymeric diol having an average molecular weight within the range of 1200 to 2500, (b) 2.3% of the average molecular weight of the polymeric diol.
~4.7 moles of alicyclic organic diisocyanate, (c)
A polyurethane composition comprising a polyurethane synthesized from an alicyclic organic diamine and (d) hydrazine, and a solvent for this polyurethane, and the following conditions (i) to (iv) (i) Alicyclic organic diisocyanate Isophorone diisocyanate or general formula (However, R ₁ and R ₂ represent a hydrogen atom or a lower alkyl group) or a mixture of both; (ii) the alicyclic organic diamine is isophorone diamine or a diisocyanate compound represented by the general formula (However, R ₃ and R ₄ represent a hydrogen atom or a lower alkyl group) or a mixture of both, and the total amount of alicyclic organic diisocyanate, alicyclic organic diamine and hydrazine is (iii) the ratio of hydrazine to the total amount of hydrazine and alicyclic organic diamine is 0.05 to 0.5 in molar ratio;
(iv) 3 to 70% by weight of the solvent has the general formula R(CH ₂ ) _o OH
(However, in the formula, when R is a hydrogen atom, n is an integer from 0 to 4, and when R is a methoxy group, ethoxy group, or acetoxy group, n
2) and 97 to 30% by weight of a solvent other than an amide-based or sulfoxide-based aprotic polar solvent. A polyurethane composition with properties suitable as a coating agent. 2. The polyurethane composition according to claim 1, wherein the polymeric diol is a diol mainly consisting of at least one type of chain selected from the group consisting of polyester chains and polycarbonate chains. 3. The polymer diol is either a diol containing an ethylene oxide structural unit, or a mixed diol of a diol containing an ethylene oxide structural unit and a diol not containing it, and the ethylene oxide structure in the polymer diol is 3. The polyurethane composition according to claim 1, wherein the proportion of the units is 5 to 50% by weight based on the total polymeric diol. 4. The polyurethane composition according to any one of claims 1 to 3, wherein 5 to 50% by weight of the solvent is methanol.