JP2009298934A - Polyurethane elastomer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane elastomer that has high water resistance without reducing physical properties such as mechanical strengths, solvent resistance, etc., in a polyester-based polyurethane elastomer. <P>SOLUTION: In the polyurethane elastomer comprising at least a succinic acid-based polyester polyol and a polyisocyanate, a succinic acid-based polyester polyol that is obtained by using succinic acid as a main component of a carboxylic acid component and 3-50 mol% of an aromatic carboxylic acid in the whole carboxylic acid components is used as the succinic acid-based polyester polyol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyurethane elastomer. In detail, it is related with the polyurethane elastomer excellent in solvent resistance and water resistance by using specific polyester polyol.

  Polyurethane elastomers are excellent in mechanical strength, wear resistance, low temperature characteristics, etc., and have a wide range of hardness and elasticity, so various materials such as waterproof materials, flooring materials, paving materials, adhesives, sealing materials, rollers, etc. Used as a component of industrial equipment.

  A polyurethane elastomer is a material obtained by reacting a polyol and a polyisocyanate together with a crosslinking agent. Polyurethane elastomers are classified according to the polyol component used, and include polyether-based, polyester-based, polycaprolactone-based, polycarbonate-based and the like. These polyol components include polytetramethylene ether glycol (PTMG) for polyethers, 1,4-butanediol adipate for polyesters, and polycaprolactone for polylactones having a number average molecular weight of about 500 to 5000. Used.

  The physical properties of polyurethane elastomers depend largely on the composition and structural characteristics of the polyol component, and are used in various applications depending on the physical properties. For example, polyurethane elastomers using succinic polyester polyols are excellent in solvent resistance and are used as polyurethane rollers for printing presses (Patent Document 1).

  On the other hand, in recent years, water-based inks are being used instead of oil-based inks from the viewpoint of environmental sanitation. However, although polyurethane elastomers using succinic polyester polyols are excellent in solvent resistance, they are inferior in water resistance and hydrolysis resistance, and therefore cannot be used for a long time in applications using aqueous ink. In addition, water-based inks that are currently widely used include water-soluble solvents such as glycol ethers, and polyurethane rollers for printing presses are required to have water resistance and solvent resistance even for water-based inks. Thus, a polyurethane elastomer having both solvent resistance and water resistance is required.

  Other than the polyurethane elastomer using succinic acid-based polyester polyol, a polyurethane elastomer using a polycarbonate-based polyol can be cited as one having excellent solvent resistance (Patent Document 2). This is excellent in solvent resistance, water resistance, and alkali resistance, and can be used in applications such as those using the above water-based ink. However, since polycarbonate polyol is generally expensive, it is difficult to use it as a general-purpose product or a consumable product, and it has a drawback that it is solid at room temperature or has a very high viscosity.

JP-A-5-301335 JP 2004-217844 A

  Accordingly, an object of the present invention is to provide a polyurethane elastomer excellent in solvent resistance and water resistance, which is inexpensive and can be used for general purposes.

  As a result of intensive studies by the inventors to achieve these objects, the inventors have obtained knowledge that the above problems can be solved by using a polyester polyol having a specific structural characteristic as a raw material for a polyurethane elastomer. It came to be completed. That is, in the succinic polyester polyol having high solvent resistance, it was found that water resistance can be imparted while maintaining solvent resistance by further using an aromatic carboxylic acid as a carboxylic acid component, and the present invention has been completed. .

That is, this invention has the summary characterized by the following.
(1) In a polyurethane elastomer composed of at least a succinic polyester polyol and a polyisocyanate, the succinic polyester polyol uses succinic acid as a main component of the carboxylic acid component, and an aromatic carboxylic acid is further added to all of the carboxylic acid components. A polyurethane elastomer obtained by using ~ 50 mol%.
(2) The polyurethane elastomer as described in (1) above, wherein the aromatic carboxylic acid is at least one selected from the group consisting of phthalic acid, isophthalic acid and terephthalic acid.
(3) The polyurethane elastomer as described in (1) or (2) above, wherein the hydroxyl value of the succinic polyester polyol is 20 to 200 mgKOH / g.
(4) The alcohol component of the succinic polyester polyol is at least one selected from the group consisting of ethylene glycol, diethylene glycol, and triethylene glycol. The polyurethane elastomer described.

  According to the present invention, a polyurethane elastomer excellent in solvent resistance and water resistance can be provided.

  Hereinafter, the present invention will be described in detail. The polyester polyol is obtained by esterifying both using a polyvalent carboxylic acid as a carboxylic acid component and a polyhydric alcohol as an alcohol component. The succinic polyester polyol in the present invention is a carboxylic acid component. It is a polyester polyol obtained by using succinic acid as a main component and further using an aromatic carboxylic acid in combination.

  In the present invention, the aromatic carboxylic acid used together with succinic acid includes aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and these may be used alone. Two or more kinds may be used in combination. Among these, at least one selected from the group consisting of phthalic acid, isophthalic acid and terephthalic acid is preferable, and phthalic acid is most preferable. In addition, as some or all of these aromatic carboxylic acids, acid anhydrides such as phthalic anhydride and ester derivatives such as dimethyl terephthalate may be used.

  The amount of these aromatic carboxylic acids used is usually in the range of 3 to 50 mol% in the total carboxylic acid component. If the amount used is less than 3 mol%, the improvement in water resistance is not observed, and if it exceeds 50 mol%, the solvent resistance deteriorates. The preferred amount is 5 to 45 mol%, more preferably 10 to 40 mol%. On the other hand, the amount of succinic acid used as the main component of the carboxylic acid component is 50 mol% or more of the total carboxylic acid component. Although it is preferable to use only succinic acid and aromatic polyvalent carboxylic acid in combination, other carboxylic acids can be used in combination within the above range. Examples of such carboxylic acids include carboxylic acids usually used for the synthesis of polyester polyols such as glutaric acid, adipic acid, sebacic acid, azelaic acid, malic acid, fumaric acid, maleic acid, and hexahydrophthalic acid. Two or more of these may be used in combination. In addition, when an acid anhydride and ester derivative are used as aromatic carboxylic acid, the usage-amount is calculated as a usage-amount (mol number) of corresponding carboxylic acid.

  In the present invention, the alcohol component used for obtaining the polyester polyol is a polyhydric alcohol such as ethylene glycol, diethylene glycol, triethylene glycol, and the like, and at least one selected from the group consisting of ethylene glycol, diethylene glycol, and triethylene glycol is used. It is preferable to use it. By using these polyhydric alcohols, the solvent resistance of the succinic polyester polyol can be further improved. Most preferred are diethylene glycol and triethylene glycol, which may be used alone or in combination.

  Other alcohol components that can be used include tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, glycerin, trimethylolpropane Aliphatic and alicyclic alcohols such as pentaerythritol, erythritol and sorbitol, aromatic alcohols and phenols such as benzyl alcohol and 2-phenoxyethanol, polyethylene glycol, polypropylene Glycol, may be used polyoxyethylene / polyoxypropylene copolymer glycol, and the normal alcohol used in the synthesis of polyester polyols such as long-chain polyether polyols such as polytetramethylene ether glycol. Two or more of these may be used in combination.

  The hydroxyl value of the succinic polyester polyol of the present invention is in the range of 20-200 mgKOH / g, preferably 25-190 mgKOH / g, more preferably 30-180 mgKOH / g. If the hydroxyl value is less than 20 mg KOH / g, synthesis may be difficult, and the viscosity may increase and handling may be difficult. On the other hand, if it exceeds 200 mg KOH / g, a molecular weight distribution with a large amount of unreacted alcohol will result. It is not preferable because the physical properties such as flexibility and brittleness may be lowered.

  The average functional group number of the succinic polyester polyol of the present invention is usually in the range of 1.5 to 3.0. Preferably it is the range of 1.8-2.5. If the average number of functional groups is less than 1.5, the mechanical strength of the resulting polyurethane elastomer may be lowered. On the other hand, when it is larger than 3.0, the viscosity of the polyester polyol is increased, which may make handling difficult. The most preferred average number of functional groups is 2.0.

  In the synthesis of the succinic polyester polyol of the present invention, an esterification catalyst is usually used. In general, an acid catalyst is often used as an esterification catalyst. Examples of Lewis acids include orthotitanates such as tetraisopropyl titanate and tetra-n-butyl titanate, and tin compounds such as diethyltin oxide and dibutyltin oxide. And metal compounds such as zinc oxide are used. In addition to a Lewis acid, a Bronsted acid such as p-toluenesulfonic acid can also be used.

  It is desirable that the catalyst used for the synthesis of the succinic polyester polyol does not affect the reaction behavior of the urethanization reaction. Therefore, among the above esterification catalysts, orthotitanate is preferable, and the amount used is usually 0.1% by weight or less, preferably 0.05%, based on the total of the carboxylic acid component and alcohol component used in the raw material. It is usually 0.001% by weight or more, preferably 0.003% by weight or less in terms of% by weight or less. In some cases, the reaction may be carried out without using these esterification catalysts, and a deactivation treatment may be performed after the reaction, or it may be removed by purification or the like.

  For production of the succinic polyester polyol of the present invention, a general polyester polyol production apparatus and reaction method can be applied. The end point of the reaction is usually determined by the amount of unreacted carboxyl groups of the carboxylic acid component used. If an acid content is present in the polyurethane elastomer, the hydrolysis resistance may decrease. Therefore, it is preferable that the amount of unreacted carboxyl groups, that is, the acid value of the polyester polyol is as low as possible. Accordingly, the acid value of the succinic polyester polyol of the present invention is usually 3 mgKOH / g or less, preferably 2 mgKOH / g or less, more preferably 1 mgKOH / g or less. Although there is no particular lower limit, it is 0.1 mgKOH / g based on the reaction conditions and reaction time.

  Examples of a general method for producing a polyurethane elastomer include a one-shot method and a prepolymer method. The one-shot method is a method of obtaining a polyurethane elastomer by simultaneously reacting a polyisocyanate component, a polyol component and, if necessary, a cross-linking agent and other auxiliary agents, and the prepolymer method is a polyisocyanate component, a polyol component and other if necessary In this method, an auxiliary agent is reacted to produce an isocyanate prepolymer, and then a crosslinking agent and other auxiliary agent are further reacted as required to obtain a high molecular weight polyurethane elastomer. As a method for producing the polyurethane elastomer of the present invention, a prepolymer method is preferred for the purpose of producing a polyurethane elastomer having stable physical properties.

   The polyisocyanate component is not particularly limited as long as it is an organic compound having two or more isocyanate groups in one molecule. For example, aliphatic such as hexamethylene diisocyanate, alicyclic such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate and xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, polyphenylene polymethylene polyisocyanate, etc. Aromatic polyisocyanates or modified products thereof can be mentioned. Furthermore, carbodiimide modified products and urethane modified products of these polyisocyanates are also included. Preferred polyisocyanates are diphenylmethane diisocyanate and hexamethylene diisocyanate.

  As the polyol component, at least the succinic polyester polyol of the present invention is used. Other than the succinic polyester polyol of the present invention, those that can be used in combination include polyether polyols such as polypropylene glycol (PPG) and polytetramethylene ether glycol (PTMG), polyester polyols such as adipic acid esters, and polycaprolactone. And polylactone polyols, polycarbonate polyols and the like. Those having a number average molecular weight of about 500 to 5,000 can be suitably used. When used in combination with the succinic polyester polyol of the present invention, the amount of the polyol component other than the succinic polyester polyol of the present invention is desirably 50% by weight or less of the ratio of the total polyol. Most preferred is a succinic polyester polyol.

  Examples of the crosslinking agent include compounds having two or more active hydrogens in one molecule such as alcohols such as ethylene glycol, diethylene glycol, 1,4-butanediol, propylene glycol and glycerin, and alkanolamines such as diethanolamine and triethanolamine. Used. Preferred examples of the crosslinking agent include ethylene glycol and 1,4-butanediol.

   In the polyurethane elastomer of the present invention, other auxiliary agents are used as necessary. Other uses of auxiliary agents are mainly catalysts for promoting or slowing urethanization reaction, reactivity modifiers, plasticizers, fillers, antioxidants, defoamers for adjusting the properties of polyurethane elastomers. , Surfactants and the like. These additives and auxiliaries are not particularly limited, and are used for the purpose of improving physical properties and operability in ordinary polyurethane elastomers, and are used within the range where the effects of the present invention can be obtained. May be.

   EXAMPLES Specific examples of the present invention will be described below in more detail with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.

<Synthesis of polyol>
“Polyols 1 to 4” were synthesized using the carboxylic acids and alcohols listed in Table 1 in accordance with known polyester polyol synthesis methods. Moreover, polytetramethylene ether glycol ("PTMG1000" manufactured by Mitsubishi Chemical Corporation) was used as "Polyol-5".

The acid value, hydroxyl value, viscosity and number average molecular weight of “Polyol-1 to 5” were measured by the following methods, and the results are shown in Table 1.
(1) Acid value: measured in accordance with JIS K1557 ₁₉₇₀ .
(2) Hydroxyl value: Measured according to JIS K1557 ₁₉₇₀ .
(3) Viscosity: Measured according to JIS K1557 ₁₉₇₀ . (25 ° C)
(4) Number average molecular weight: Determined according to JIS K1601 ₁₉₈₂ .

<Synthesis of isocyanate prepolymer>
The following raw materials and reactivity modifiers were used for the synthesis of the isocyanate prepolymer.
(1) Polyol-1 to 5: The above polyol (2) Polyisocyanate: Diphenylmethane diisocyanate (“Millionate MT” manufactured by Nippon Polyurethane Industry Co., Ltd.)
(3) Reactivity regulator: Phosphate ester (“JP-508” manufactured by Johoku Chemical Co., Ltd.)

Isocyanate prepolymers “Prepolymer-1 to 5” were synthesized according to the following method using the above-mentioned raw materials and reactivity control agents.

<Synthesis Method of Isocyanate Prepolymer>
A glass reactor equipped with a stirrer, thermometer, pressure gauge, oil bath, etc. and having a volume of 1 liter is charged with polyol, polyisocyanate, and reactivity modifier according to the mixing ratio shown in Table 2, Was defoamed under reduced pressure. Thereafter, the space of the reactor was replaced with nitrogen gas, and then the reactor was started to be heated at normal pressure. The reaction was started when the internal temperature reached 80 ° C., and the reaction was carried out for 2 hours while depressurizing the system and degassing every 30 minutes from the start of the reaction. The isocyanate prepolymer obtained here was shown in Table 2 as "Prepolymer-1 to 5".

The% NCO (terminal isocyanate group concentration) of the isocyanate prepolymer was measured according to JIS K1556 ₁₉₆₈ using dimethylformamide as a solvent, and the results are shown in Table 2.

<Synthesis of polyurethane elastomer>
The following prepolymer and crosslinking agent were used for the synthesis of the polyurethane elastomer.
(1) Prepolymer: Prepolymer-1 to 5
(2) Crosslinking agent: 1,4-butanediol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent)

A polyurethane elastomer sheet was molded by the following molding method.

<Molding method>
A predetermined amount of prepolymer preheated to 80 ° C. was weighed into a SUS reactor, and after a predetermined amount of a crosslinking agent was added by a syringe, it was immediately set in a vacuum stirrer and stirred for 30 seconds while degassing under reduced pressure. . Thereafter, the preheated prepolymer was poured into a molding die of a 2 mm thick sheet that had been preheated to 80 ° C., and was heated and cured in a 120 ° C. oven overnight. Thereafter, the polyurethane elastomer sheet was demolded and stored in the room for 2 days or longer, and then the properties of the polyurethane elastomer sheet were evaluated. The blending ratio of the prepolymer and the crosslinking agent was 1.05 in terms of isocyanate index (NCO group / OH group molar ratio).

The following materials were used as the mold and release agent for polyurethane elastomer sheet molding.
(1) Die: Aluminum Internal dimensions 200mm x 200mm x 2mm
(2) Release agent: Fluorine-based release agent spray ("Daifree GA-6010" manufactured by Daikin Industries, Ltd.)

<Evaluation method>
The evaluation test of the obtained polyurethane elastomer was carried out by the following method. The mechanical strength of the polyurethane elastomer was shown in Table 3, and the evaluation results of water resistance and solvent resistance were shown in Tables 4-7.

(1) the mechanical strength of the mechanical strength test polyurethane elastomer was measured in accordance with JIS A7311 _1995, the hardness of the polyurethane elastomer has been described and the results measured in accordance with JIS K711 ₁₉₉₅ Table 3. The following tensile test pieces and tear test pieces were used.
Tensile test piece: JIS K7113 No. 2 Tear test piece: JIS K7311 No. 3

(2) Water resistance test After a test piece for mechanical strength measurement was immersed in water (60 ° C) for 1 week, the change in the weight of the test piece and the change in the test result by the mechanical strength test in (1) above were measured. The change in weight before and after immersion of the test piece and how much the original mechanical strength was lost was taken as the evaluation result of water resistance. The evaluation results are based on the weight of the specimen before immersion and the mechanical strength test values (breaking strength, elongation at break, 100% modulus, 200% modulus, 300% modulus, elastic modulus, tear strength) after immersion. The ratio (%) is shown in Table 4.

(3) Solvent resistance test A test piece for measuring the mechanical strength was immersed in (a) toluene, (b) ethyl acetate, and (c) isopropyl alcohol for 1 week at 20 ° C. Thereafter, the test piece was taken out, and the change in the weight of the test piece and the change in the test result by the mechanical strength test (1) were measured. The test results for solvent resistance were the weight change before and after immersion of the test piece and how much the original mechanical strength was lost. The evaluation results are based on the weight of the specimen before immersion and the mechanical strength test values (breaking strength, elongation at break, 100% modulus, 200% modulus, 300% modulus, elastic modulus, tear strength) after immersion. The ratios (%) are shown in Tables 5 to 7.

  In Tables 4 to 7, the tensile test results (breaking strength, breaking elongation, 100% modulus, 200% modulus, 300% modulus and elastic modulus) and tear test results (tear strength) values (with respect to the values of the test pieces before immersion) The arithmetic average of (ratio) was described as an average strength value, and was used as an index for a decrease in mechanical strength.

  From Table 3, the following is clear. That is, in the evaluation of mechanical strength of polyurethane elastomer (breaking strength, breaking elongation, 100% modulus, 200% modulus, 300% modulus, elastic modulus and tear strength), the succinic acid-based polyester combined with the aromatic carboxylic acid of the present invention In the case of Examples 1 and 2 using a polyol, compared with Comparative Examples 1 to 3 using Polyol-3, which is a normal succinic polyester polyol, and Polyols 4 and 5 used for general purposes, there is no particular inferiority. It can be said that it has physical properties.

  From Table 4, the following is clear. That is, in the water resistance evaluation of the polyurethane elastomer, in the case of Examples 1 and 2 using the succinic polyester polyol of the present invention in combination with an aromatic carboxylic acid, the strength average value and weight after immersion in water (60 ° C.) The change is improved as compared with Comparative Example 1 using a succinic polyester polyol that does not use an aromatic carboxylic acid in combination, and it is not inferior to Comparative Examples 2 and 3 using a generally used polyol. This shows that when the polyol of the present invention is used, the water resistance of the polyurethane elastomer is improved.

  Moreover, the following is clear from Tables 5-7. That is, in the solvent resistance evaluation of the polyurethane elastomer, in the case of Examples 1 and 2 using the succinic acid-based polyester polyol of the present invention in combination with an aromatic carboxylic acid, the strength average value after the solvent immersion is generally used. Compared with Comparative Examples 2 and 3 using the polyol obtained, the weight is equivalent or higher, and the increase in weight due to swelling is small. Moreover, even if it compares with the comparative example 1 using the succinic-acid type | system | group polyester polyol which does not use aromatic carboxylic acid together, there is no inferiority. This indicates that the solvent resistance of the polyurethane elastomer maintains the performance of a normal succinic polyester polyol.

  ADVANTAGE OF THE INVENTION According to this invention, the polyurethane elastomer excellent in solvent resistance and water resistance can be provided.

Claims (4)

  In a polyurethane elastomer comprising at least a succinic polyester polyol and a polyisocyanate, the succinic polyester polyol uses succinic acid as a main component of the carboxylic acid component, and further aromatic carboxylic acid is 3 to 50 mol% in the total carboxylic acid component. A polyurethane elastomer obtained by using the polyurethane elastomer.   The polyurethane elastomer according to claim 1, wherein the aromatic carboxylic acid is at least one selected from the group consisting of phthalic acid, isophthalic acid and terephthalic acid.   The polyurethane elastomer according to claim 1 or 2, wherein the hydroxyl value of the succinic polyester polyol is 20 to 200 mgKOH / g.   The polyurethane elastomer according to any one of claims 1 to 3, wherein the alcohol component of the succinic polyester polyol is at least one selected from the group consisting of ethylene glycol, diethylene glycol, and triethylene glycol. .