JPH08165321A - Production of polyurethane urea molding - Google Patents

Abstract

PURPOSE: To produce a polyurethane urea solution which is transparent and stable, is suppressed in a viscosity change and gel formation and can give a molding of good properties by using a specified compound as the solvent in the production of a polyurethane solution. CONSTITUTION: A compound of the formula (wherein n is 2 or 3) is used as an organic solvent in producing a polyurethane urea molding by removing the solvent, by a wet or dry process, from a polyurethane urea solution obtained by the chain extension of a prepolymer obtained by reacting an organic diisocyanate with a linear molecule having two active hydrogen atoms and a molecular weight of 350-4000 (e.g. polyether glycol, polyester glycol or a copolymer or mixture thereof) with a diamine or a mixture thereof with a monoamine in the organic solvent. According to this process, the change with time otherwise occurring in a conventional polyurethane solution can be prevented, and a molding excellent also in properties can be produced by changing the agglomerative properties of the polymer during the solvent removal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane urea molded article (hereinafter simply referred to as a polyurethane molded article). Specifically, using a terminal isocyanate prepolymer of an organic diisocyanate based on 4,4′-diphenylmethane diisocyanate as an organic diisocyanate and a diol having two active hydrogens,
The present invention relates to a method for producing a transparent and stable polyurethane solution by carrying out a chain extension reaction in a diamine or a diamine / monoamine mixed system in an organic solvent, and producing a molded product therefrom.

[0002]

2. Description of the Related Art Conventionally, a polyurethane urea solution (hereinafter simply referred to as a polyurethane solution) having substantially no crosslinked structure is used to form elastic fibers, elastic films, various elastomer-like molded products, surface films of artificial leather, various paints, etc. Various articles having excellent rubber-like elasticity for the surface coatings, impregnants and the like have been manufactured. This polyurethane solution is produced by two steps of performing a prepolymerization reaction with an organic diisocyanate and a relatively high molecular weight diol, and then adding a solvent and then performing a chain extension reaction using a diamine or the like. The method using this solution is generally easier to handle because it can handle a fluid system at room temperature than the method of molding it by heating and melting solid polyurethane as it is, and it is simpler in terms of equipment and process. There is a feature that can be manufactured.

However, even in the case of producing a polyurethane urea (hereinafter simply referred to as polyurethane) using a solution, the higher the polymer concentration in the solution (hereinafter referred to as NV) is, the polyurethane having an isocyanate group at the end. The reaction rapidly and locally proceeds at the stage of the reaction between the prepolymer and the polyvalent amino compound,
When the viscosity of the solution rises, there are some areas where there is no fluidity and where there is fluidity, and when the viscosity rises too much, the whole becomes solid without fluidity (hereinafter gel). Will be called). When the solution becomes non-uniform due to the increase in the viscosity of the chain extension reaction, the workability such as molding and impregnation thereafter becomes extremely poor, and immediately after the reaction, a uniform and transparent solution is formed. Even if it is obtained, the viscosity and properties of the solution change rapidly or gradually due to subsequent storage, resulting in "turbidity" or "gelation".
In addition, there are many troubles caused by instability of the solution, such as impairing workability, and the problem of the solution property mainly due to the rapid reaction is large in the production method and processing technology of this type of polymer. It is a problem.

As a method for solving such a problem, it is considered to produce a stable solution which is transparent and does not easily gel. For example, Japanese Patent Publication No. 47-637 discloses adipate polyol and polytetramethylene glycol. However, the advantages of adipate polyol and polytetramethylene glycol are not utilized, and the performance is inferior to the use of a single substance, resulting in a new problem. Japanese Examined Patent Publication No. 47-35317 discloses a method for stabilizing a stable polyurethane solution by chain extension using a diamine having an equivalent amount of an isocyanate group or less and water, but the procedure is complicated and complicated. It is not preferable because the physical properties deteriorate.

Japanese Patent Publication No. 49-11476 discloses a method for producing a stable polyurethane solution by introducing a urethane prepolymer into a chain extender solution.
A high viscosity prepolymer must be inserted into the reactor, which is difficult to do. Japanese Patent Publication No. 49-40006 discloses a method for producing a polyurethane polymer solution using an alicyclic diamine, an aromatic dimethylamine, and a substituted iminobisaliphatic amine. Diamine must be used, which is an industrial and economical disadvantage. Japanese Unexamined Patent Publication (Kokai) No. 47-15498 discloses a method for producing a polyurethane polymer solution using metal acetylacetone, but it is disadvantageous in terms of physical properties because the metal content is mixed in the product. JP-A-48-12
Japanese Patent No. 347 discloses a method for stabilizing a polyurea elastomer solution by adding lithium formate and sodium acetylacetone, but it is industrially disadvantageous because both lithium formate and sodium acetylacetone are expensive reagents. . Japanese Unexamined Patent Publication (Kokai) No. 3-139514 discloses a polyurethaneurea elastomer using a lithium salt and an aliphatic alicyclic chain terminator, but it is economical to carry out because it uses a special reagent for production. There are technical difficulties.

Japanese Unexamined Patent Publication (Kokai) No. 3-279415 discloses a polyurethane elastic fiber using a symmetric diamine and an asymmetric diamine, but there is a drawback that the tensile strength is lowered by using the asymmetric diamine.
Japanese Unexamined Patent Publication No. 50-78698 describes a method for producing a polyurethane solution by specifying the addition conditions of hydrazine and diamine solutions. However, the operation is complicated and elastic fibers and transparent elastic films can be produced. It has a drawback that it does not have a proper elasticity. Furthermore, JP-A-2-70720
There is also an example of pulverizing a spinning solution that has gelled, as in Japanese Patent Publication No. JP-A-2003-187, but it is effective as a method for pulverizing a gelled solution to make it usable, but from the beginning It is not necessary if a polyurethane solution that is difficult to gel can be synthesized. These solutions do not simultaneously satisfy both the above-mentioned drawbacks as well as the economical aspects of using expensive reagents and the process aspects such as complicated operations.

It is also known that when a solvent is evaporated from a polyurethane solution to produce a molded article such as casting, spinning, and wet spinning, the mechanical properties of the molded article change depending on the type of the solvent. . For example, it is known from Vol. 51, pp. 605-611 of High Polymer Papers that the tensile properties of cast films of styrene-butadiene copolymer graft compounds differ depending on the type of solvent. However, in the conventional polyurethane solution, N, N-dimethylformamide, N, N are generally used as the solvent.
Although N-alkyl-substituted amides such as -dimethylacetamide are used, no significant change in physical properties is observed even if the type of these solvents is changed.

[0008]

The problem to be solved by the present invention is to use a stock solution for spinning, a film or a solution for molding without using a special reagent or a complicated operation as in the conventional method. , As a coating solution for surface coating, or as an impregnating agent, an adhesive solution, a transparent and good stability, good workability, to obtain a polyurethane solution, and for the purpose of removing the solvent to improve the physical properties of the molded article, To control the reaction between the prepolymer and the chain extender, and the change over time after the reaction to obtain a polyurethane solution with good stability, and to control the microphase separation structure when removing the solvent to produce molded products with high physical properties. Is.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a reaction with a linear molecule having a molecular weight of 250 to 4000 and containing two organic diisocyanates and active hydrogen. When the resulting prepolymer is diluted with a solvent and a polyurethane solution is produced by chain extension using a solution of a diamine / monoamine mixture, it is allowed to stand at room temperature (25 ° C) by using a specific organic solvent. Even if it does not gel for more than 30 days, it is possible to produce a polyurethane solution having stable properties when used, and as a result,
The present invention has been accomplished by finding that the mechanical strength of the obtained polyurethane molded product is increased.

That is, the present invention provides the following (1) and (2)
It is as follows. (1) After producing a prepolymer by reacting an organic diisocyanate with a linear molecule having two active hydrogens and a molecular weight of 250 to 4000, using a diamine or a mixture of a diamine and a monoamine in an organic solvent. In the method for producing a polyurethane molded article by removing a solvent from a polyurethane solution obtained by chain extension by a wet or a dry method, the compound represented by formula (I)

Embedded image A method for producing a polyurethane molded article, which comprises using a compound represented by the formula (wherein n is 2 or 3). (2) The method for producing a polyurethane molded article according to (1), wherein the compound represented by the general formula (I) is N, N′-dimethylimidazolidinone.

By using such a specific organic solvent, the inventors of the present invention can control the microphase-separated structure of the polymer during the chain extension reaction or during the removal of the solvent during the production of a molded article, thereby controlling the polyurethane structure. The stability of the solution was dramatically increased, and as a result, the mechanical strength of the molded product could be increased.

The method for producing a polyurethane solution according to the present invention comprises the following two steps as in the known method. That is, a molecular weight of 250 to 4000 having two active hydrogens.
The first step of producing an isocyanate-terminated prepolymer by the reaction of the linear molecule with an organic diisocyanate, after dissolving the isocyanate-terminated prepolymer in a solvent, charging a solution of diamine or a diamine / monoamine mixture. This is the second step in which the chain extension reaction is carried out.

The first step of the production of the polyurethane solution is produced by reacting a linear molecule having two active hydrogens and a molecular weight of 250 to 4000 with an excess amount of an organic diisocyanate in an equivalent ratio. As the organic diisocyanate, the organic diisocyanate usually used in polyurethane chemistry can be used. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4 ′
-Diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, naphthylene diisocyanate, or
These mixtures are mentioned. 2,4 ', 2,2'-is preferably used because of the physical properties of the molded product.
It is 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI) containing diphenylmethane diisocyanate. In addition, MDI may be available in solid form,
It may be obtained and used in the molten state, but the MDI in the molten state
Is preferable because it can save the dissolving work.

Molecular weight of 250 to 4000 having active hydrogen
Examples of the straight-chain molecule include polyether glycol, polyester glycol, and copolymers and mixtures thereof. If the molecular weight is less than 250, the elastic performance is poor, and if it exceeds 4000, it becomes difficult to produce polyether glycol or polyester glycol. The main types of suitable polyether glycols are polyalkylene ethers such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexamethylene glycol and the like. Further, a random copolymer produced from a mixture of monomers used in producing these or a block copolymer produced by changing the production method can also be used. Polytetramethylene glycol is preferably used because of its physical properties.

Polyester glycols are known as
It is obtained by polycondensation of a dibasic acid and a low molecular glycol.
Dibasic acids include succinic acid, adipic acid, speric acid,
Sebacic acid, terephthalic acid, hexahydroterephthalic acid, azelaic acid, etc. are used, and as low molecular glycols, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
Neopentyl glycol, 1,6-hexamethylene glycol, cyclohexane-1,4-diol and the like can be used.

The equivalent ratio of the organic diisocyanate to the linear molecule having two active hydrogens and having a molecular weight of 250 to 4000 is preferably 1.1 to 2.4, and more preferably 1.4 to.
It is 2.0. When the equivalence ratio is 1.0, that is, when the equivalence ratio is equal, the molecular weight becomes substantially infinite in this first step, and there is a possibility that subsequent synthesis may become impossible, which is not preferable, and the equivalence ratio is 2.4. A large amount of organic diisocyanate that does not react above the terminal isocyanate prepolymer causes the solution to become opaque during the subsequent chain extension reaction, a large amount of insoluble components are formed, and the viscosity increases rapidly and the stirring blade It is not preferable because it may cause things such as being entangled in.

In the charging step of the first step, whichever of the organic diisocyanate and the linear molecule having a molecular weight of 250 to 4000 having two active hydrogens is batchwise or a time sufficiently shorter than the time for the reaction to proceed It does not matter which one is charged and reacted, but when the organic diisocyanate is added little by little to a linear molecule having a molecular weight of 250 to 4000 having two active hydrogens, or when continuously charged with a metering pump or the like,
Note that if the charging is carried out for too long, the molecular weight will be virtually infinite as well.

The reaction temperature in the first step is preferably 50 to 1
20 ° C., more preferably 80 to 100 ° C., 50
If the reaction temperature is lower than ℃, the reaction time will be prolonged, which is not industrially preferable, and if the reaction temperature is higher than 120 ° C, side reactions such as the formation of alohanate bonds will occur, resulting in an increase in viscosity and gelation. It is not preferable because it causes it.

As the solvent used in the second step, an organic solvent represented by the general formula (I) is used, and if necessary, N, N-dimethylformamide and N, N-diethylformamide known in polyurethane chemistry are used. , N-methylformanilide, N-formylpiperidine, N, N-dimethylacetamide, N, N-diethylacetamide,
N, N-dimethylpropionamide, N-methyl-α-
N-substituted amides such as pyrrolidone, N-methyl-α-piperidone and N-methylcaprolactam, N-tetramethylurea, N-acetyl-α-pyrrolidone, N-acetyl-α-piperidone, N-acetylcaprolactam and other N N such as substituted ureas and N-tetramethylthiourea
Substituted thioureas, dimethyl sulfoxide, tetramethylene sulfoxide, diethyl sulfoxide, diisopropyl sulfoxide, di-n-propyl sulfoxide, diisobutyl sulfoxide, di-n-butyl sulfoxide, and other sulfoxodes, and hexamethylphosphorylamide, hexaethylphosphorylamide, etc. The N-substituted phosphorylamides may be used in combination, but the amount of the solvent used in combination is preferably less than 30% in order to exhibit the characteristics of the solubility of the organic solvent represented by the general formula (I). . Further, since the water content in the solvent reacts with the isocyanate group, it is desirable to carry out dehydration and purification using distillation or a dehydrating agent such as molecular sieves.

The diamine is one that is chain-extended with the terminal isocyanate prepolymer, and may be any one that has two primary or secondary amino groups capable of reacting with the isocyanate group in the molecule. As, for example, ethylenediamine, hydrazine, propylenediamine, trimethylenediamine, N-methyltrimethylenediamine, tetramethylenediamine, hexamethylenediamine, p-
Phenylenediamine, m-phenylenediamine, m-tolylenediamine, p-tolylenediamine, m-xylylenediamine, p-xylylenediamine, 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3, Inorganic or organic diamines such as 3'-dichloro-4,4'-diaminodiphenylmethane, 1,5-naphthylenediamine, piperazine and 1,4-cyclohexyldiamine are used, and two amide groups are included in the molecule. It is also possible to use a compound having the same, urea and a derivative thereof. The monoamine has one amino group capable of reacting with an isocyanate group in the molecule, and for example, diethylamine, dibutylamine, piperidine, aniline and the like can be used.

In the chain extension reaction of the second step, the reaction may be terminated by charging a solution of a terminal isocyanate prepolymer with a diamine solution having a smaller amount than the equivalent amount of the isocyanate group, and then charging a monoamine. Alternatively, the diamine / monoamine mixed solution may be charged from the beginning to cause the reaction, and the monoamine solution may be charged at the end to terminate the reaction. Further, an excess amount of the diamine / monoamine mixed solution may be inserted from the beginning. You may make it react. On the contrary, the terminal isocyanate prepolymer may be charged into the solution of the chain extender and the terminal terminator and reacted. In addition, when the thickening is stopped, it may be heated. The reaction temperature in the second step is lower than room temperature, preferably 1 because the reaction between the isocyanate group and the amino group is fast.
It is desirable to carry out the reaction at 5 ° C or lower. If necessary, measures such as ice cooling may be taken. Known additives, for example,
Dyes, pigments, antioxidants, matting agents, antistatic agents, UV absorbers, etc. can also be added to the obtained polyurethane solution.

According to the method of the present invention, a polyurethane solution having a polymer concentration of 10% to 60%, which can be suitably used as a stock solution for spinning, a film or a solution for molding, etc., is obtained, and a polyurethane molded product having good physical properties is obtained therefrom. Can be manufactured.
In the method of the present invention, the method of removing the solvent when producing a molded product from the polyurethane solution may be a method of putting the polyurethane solution in water or a water / organic solvent mixed system and dissolving it to remove the solvent. Alternatively, a method of putting the polyurethane solution in vacuum at high temperature and removing the solvent by evaporation may be used. The shape of the molded article in the method of the present invention can be formed into a film, a sheet, a filamentous body or the like by the molding method.

[0023]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but these examples do not limit the present invention. The results of Examples and Comparative Examples are shown in Table 1. Unless otherwise specified, all parts and ratios are by weight.

[0024]

[Table 1]

The physical properties of the examples and comparative examples were measured by the following methods and devices. Tensile strength, elongation: The tensile strength and elongation of the film are 25
It was measured by Tensilon at 0 ° C. (extension rate is 300 mm / min). Stress relaxation rate: The stress relaxation rate was calculated according to the following procedure. The test piece is stretched by 300%, left for 1 minute, then returned to its original position and left for 3 minutes. Repeat this to calculate the ratio of the stress after 5 minutes left for 1 minute and the stress at 1st 300% elongation by the following formula (JIS
L-1096 was applied). Stress relaxation rate = 100 × (T−T ′) / T (T: stress at the first 300% elongation, T ′: stress after the fifth standing for 1 minute)

Example 1 1177 parts of polyhexamethylene glycol (hereinafter referred to as PTMEG) having a number average molecular weight of 1984 and 4,4'-
223 parts of MDI (manufactured by Mitsui Toatsu Chemicals, Inc.) consisting of 99.0% of diphenylmethane diisocyanate (hereinafter referred to as 44MDI) and 1.0% of 2,4′-diphenylmethane diisocyanate (hereinafter referred to as 24MDI) After being charged in a glass reactor, they were reacted at 85 ° C. for 120 minutes under a nitrogen stream to produce a terminal isocyanate prepolymer (hereinafter referred to as prepolymer). After the reaction, a prepolymer, N, N'-dimethylimidazolidinone (hereinafter referred to as DMI) 1400 was placed in a reactor equipped with a torque meter.
After stirring and dissolving the parts, the reactor was cooled with ice. A solution prepared by previously mixing 15.3 parts of ethylenediamine, 4.1 parts of diethylamine, and 4180 parts of DMI was added to the reactor within 1 minute, and the reaction was carried out at 15 ° C or lower.
When the value of the torque meter is stable, the ice cooling is stopped, and 28.0 parts of antioxidant Nocrac NS-30 (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) as an additive, T-328 (Ciba-gaigi)
9.8 parts was added, and the temperature of the reactor was raised to 50 ° C. as a post reaction to obtain a transparent polyurethane solution. The polymer concentration after the reaction was 20%. The viscosity of this polyurethane solution immediately after synthesis was 11,000 centipoise (cps) at 25 ° C. After casting the synthesized polyurethane solution on a clearance glass plate, 1
It was dried at 00 ° C. for 6 hours to prepare a film having a thickness of 100 μm, and the film was subjected to a physical property test. Furthermore, when the stability was visually measured, the polyurethane solution was sufficiently stable at 25 ° C. for 30 days or longer without gelation or turbidity.

Example 2 According to Example 1, PTMEG having a number average molecular weight of 1984
PTMEG with a number average molecular weight of 950 instead of 1177 parts
A polyurethane solution was synthesized in the same manner except that 564 parts was used. The viscosity immediately after the synthesis was 6500 cps.
The stability of this polyurethane solution was measured to be 25
It was sufficiently stable at 30 ° C without gelation or turbidity for more than 30 days. The physical properties of the film are shown in Table 1.

Comparative Examples 1 and 2 Polyurethane solutions were synthesized in the same manner as in Examples 1 and 2 except that the organic solvent used was DMI instead of DMF. The viscosity immediately after synthesis is 6000,
It was 3900 cps. This polyurethane solution is 25
When left at 0 ° C, gelation occurred after 1 and 4 days, respectively.
The physical properties of the film are shown in Table 1.

[0029]

According to the method of the present invention, by using an organic solvent represented by the general formula (I) as a solvent used for producing a polyurethane solution, it is possible to prevent the conventional polyurethane solution from changing with time. In addition, since a molded product excellent in physical properties can be produced by changing the cohesiveness of the polymer in the solution when the solvent is removed, it is suitable as a method for producing synthetic fibers, films and the like.

Claims (2)

[Claims] 1. A prepolymer is produced by reacting an organic diisocyanate with a linear molecule having two active hydrogens and a molecular weight of 250 to 4000, and then a diamine or a mixture of a diamine and a monoamine is added in an organic solvent. In the method for producing a polyurethaneurea molded product by removing the solvent from the polyurethaneurea solution obtained by chain extension using a wet method or a dry method, the compound represented by the general formula (I): A method for producing a polyurethane urea molded article, which comprises using a compound represented by the formula (wherein n is 2 or 3). 2. A compound represented by the general formula (I) is N,
The method for producing a polyurethane urea molded article according to claim 1, which is N'-dimethylimidazolidinone.