JPH06316618A - Two-liquid casting urethane elastomer composition - Google Patents

Abstract

PURPOSE:To give a two-part casting type urethane elastomer composition having rapid expression of high physical strength. CONSTITUTION:The composition is a mixture of an isocyanate-terminal polyester prepolymer, a polyester polyol and a short-chained glycol and a short-chained triol. The isocyanate-terminal polyester prepolymer is produced in a range of 3.0 to 95.5 isocyanate/hydroxyl molar ratio. The polyester polyol, short- chained glycol and the short-chained triol are preferably poly(ethylene adipate) of 1,000 to 3,000 molecular weight, obtained from the polycondensation reaction of ethylene glycol and adipic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a two-component cast urethane elastomer composition. More specifically, the present invention relates to a two-component injection type urethane elastomer composition comprising a polyester prepolymer and polyester polyol, glycol, triol and the like, which has a rapid physical strength development and an excellent demolding property.

[0002]

2. Description of the Related Art The conventional casting techniques for cast urethane elastomers are roughly classified into two types: one-shot method and prepolymer method. The one-shot method is a method in which all reactant raw materials are mixed and stirred at once in the reactor, cast, and then almost completely reacted by primary curing, and then released, and then secondary curing is performed. Is the most economical method because it is used as is. However, since a polymerizing reaction such as urethanization proceeds at once, a large amount of heat is generated, and it is difficult to obtain stable physical properties.

On the other hand, the prepolymer method is a two-step method comprising a step of reacting a polyol and an excess of diisocyanate in advance to synthesize a prepolymer, and a step of reacting this prepolymer with other deficient raw materials to finally produce an elastomer. Take In the case of the prepolymer method, the heat associated with the urethanization reaction is already released during the prepolymerization, and most cast urethane elastomers are manufactured by this method because they have the following advantages.

(A) Since the reaction proceeds uniformly, an elastomer having high physical properties can be obtained. (B) The total calorific value is small,
Large-scale molding is possible. (C) It is possible to produce a segmented polyurethane in which a curing agent such as glycol or amine is freely selected. However, the disadvantages of this prepolymer method are that the viscosity is increased and the proportion of the liquid mixture is biased. If the viscosity is high, it may cause poor defoaming, poor mixing with the curing agent, etc.
On the other hand, if the mixed liquid ratio is biased, there is concern that the physical properties may change due to the deviation of the stoichiometric value.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the drawbacks of the conventional casting technique, especially the prepolymer method, and as a result, polyester isocyanate group-terminated prepolymer and polyester polyol, etc. By using a polyol consisting of, the change in physical properties due to the deviation of the stoichiometric value is significantly improved,
The inventors have found that the physical strength develops faster, the demolding time is shortened, the defoaming property is reduced by lowering the viscosity, and the casting workability is improved, and the present invention has been accomplished.

[0006]

Means for Solving the Problems That is, the present invention provides a urethane elastomer having a weight mixing ratio A / B of (A) a polyester isocyanate-terminated prepolymer and (B) a polyester polyol, a short chain glycol and a short chain triol mixture. Is 100/45 to 100/222, which is a two-component injection-type urethane elastomer composition having excellent demolding properties.

4,7'-diphenylmethane diisocyanate is most suitable as the polyisocyanate constituting the polyester isocyanate-terminated prepolymer which is the component (A) of the present invention. Diisocyanate, hexamethylene diisocyanate, dodecane diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, trans-cyclohexane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, lysine diisocyanate, tetramethylxylylene diisocyanate, etc., and their isomers. Body, derivative and the like, which can be used alone or as a mixture of two or more kinds.

As the polyester polyol constituting the polyester type isocyanate-terminated prepolymer which is the component (A) of the present invention, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol and 3-methyl- Malonic acid with one or more of 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, decamethylene glycol, etc. ,
It is a polyester polyol containing one or more of maleic acid, succinic acid, adipic acid, glutaric acid, pimelic acid, sebacic acid, oxalic acid, phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid and the like. A preferable polyester polyol has a molecular weight of 1,000 to 30.
Poly (ethylene adipate) having a hydroxy end group of 00.

Preparation of the polyester-type isocyanate-terminated prepolymer which is the component (A) of the present invention is carried out at an isocyanate group / hydroxyl group molar ratio of 3.0 to 95.5. The reaction between the polyisocyanate and the polyester polyol may be carried out by a conventional method, usually 50 to 100 ° C.
The reaction is carried out at the temperature of 1 to obtain an isocyanate group-terminated prepolymer.

The polyester polyol, short-chain glycol and short-chain triol constituting the component (B) of the present invention are
Poly (ethylene adipate) having a hydroxy-terminated group having a molecular weight of 1000 to 3000, which is obtained by a condensation reaction of ethylene glycol and adipic acid, is preferable.

The short-chain glycol which constitutes the component (B) of the present invention includes, for example, ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, methylpentanediol, neopentyl glycol, cyclohexanediene having a molecular weight of 62 to 250. Methanol, hydroquinone-bis (2-hydroxyethyl) ether, diethylene glycol, dipropylene glycol and the like can be mentioned.

The short-chain triol constituting the component (B) of the present invention includes, for example, glycerin, trimethylolpropane, 1,2,6-hexanetriol, 1,2,4-butanetriol, diamine having a molecular weight of 92 to 350. Glycerin, pentaerythritol, trimethylolethane, triisopropanolamine, triethanolamine, diisopropanolamine and the like can be used alone or in combination of two or more.

The polymerization mixing ratio of polyester polyol / short chain glycol / short chain triol in the component (B) of the present application is in the range of 75 to 95/5 to 25/0 to 10, respectively. The preferred range is 89.3 / 6.95 /
3.75. Outside this range, the shortening of the demolding time during molding is insufficient and the physical properties are poor.

The components (A) and (B) of the present invention are used in a weight mixing ratio A / B of 100/45 to 100/222. In this case, the component (B) has a ratio of the active hydrogen group concentration of the hydroxyl group to the isocyanate group concentration of the urethane prepolymer relative to the component (A), that is, active hydrogen group /
The isocyanate group equivalent ratio becomes 0.8 to 1.20. If necessary, reaction catalysts, additives, etc. may be used. As the casting mold, the (A) / (B) mixed liquid is poured into a preheated mold, and primary crosslinking is performed at a temperature of room temperature to 160 ° C. After this primary cross-linking, secondary cross-linking is performed at 100 ° C. to 170 ° C., and after aging, a urethane elastomer is obtained.

[0015]

INDUSTRIAL APPLICABILITY In the present invention, the heat of reaction is large and the demolding time can be shortened as compared with the prepolymer method. In addition, the obtained cured product has a change in physical properties due to the deviation of the stoichiometric value without deteriorating general physical properties such as hardness, tensile strength, elongation, and compression strain properties, as compared with the prepolymer method. Is significantly improved, physical strength is rapidly developed, demolding time during molding is short, and casting workability is also good.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. "Parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Example 1 4,4'-diphenylmethane diisocyanate (MDI) as a polyisocyanate (trade name: Millionate M)
(T, manufactured by Nippon Polyurethane Industry Co., Ltd.) 127 parts were placed in a four-neck glass flask and kept at 50 ° C. Then, 100 parts of poly (ethylene adipate) (average molecular weight 1500, hydroxyl value 74.8) was stirred under a nitrogen stream while stirring so that the isocyanate group / hydroxyl group molar ratio would be 7.6.
The reaction was carried out at a temperature of ˜70 ° C. for 3 hours to obtain a transparent and viscous prepolymer liquid A. The NCO group content is 16.
It was 3%.

Poly (ethylene adipate) (average molecular weight 1500, hydroxyl value 74.8) was used as the component (B) so that the prepolymer A liquid thus obtained had a hydroxyl group / isocyanate group molar ratio of 0.92. ) / 1,4-Butanediol / trimethylolpropane / triethylenediamine (weight ratio 89.3 / 6.95 / 3.75 / 0.0
The mixture B solution of 15) was added, and the mixture was thoroughly stirred until the A / B mixture became completely transparent, and then the vacuum pump 10 Tor was used.
Degassing was performed for 60 minutes at a reduced pressure of r or less until foaming subsided. This A / B liquid mixture was poured into a centrifugal molding machine preheated to 130 ° C., and primary curing was performed at 130 ° C. for 1 hour.
The obtained plate-like polyurethane was secondarily cross-linked at 120 ° C. for 2 hours and then aged at room temperature for 1 week to obtain a polyurethane elastomer. The results are shown in Table 1.

Example 2 In the same preparation of prepolymer A liquid as in Example 1, M
Example 1 was repeated except that 167 parts of DI and 100 parts of poly (ethylene adipate) (average molecular weight 1000, hydroxyl value 112) were used. The isocyanate group content was 17.8%. The prepolymer A liquid thus obtained had a hydroxyl group / isocyanate group molar ratio of 0.95.
(B) as poly (ethylene adipate) (average molecular weight 1000, hydroxyl value 112) / 1,4
Butanediol / trimethylolpropane / triethylenediamine (weight ratio 89.3 / 6.95 / 3.75 /
Example 1 was repeated except that the solution B of 0.015) was used. The results are shown in Table 1.

Example 3 In the same preparation of prepolymer A liquid as in Example 1, M
DI 750 parts, then poly (ethylene adipate) (average molecular weight 3000, hydroxyl value 37.4) 100 so that the molar ratio of isocyanate group / hydroxyl group is 0.95.
The same procedure as in Example 1 was carried out except that parts were used. The isocyanate group content was 29.3%. Poly (ethylene adipate) (average molecular weight 3000, hydroxyl value 3) was added as component (B) to the prepolymer A liquid thus obtained so that the molar ratio of hydroxyl group / isocyanate group was 0.92.
7.4) / 1,4-butanediol / trimethylolpropane / triethylenediamine (weight ratio 89.6 / 6.
(78 / 3.62 / 0.0109) except that the mixture B solution was used. The results are shown in Table 1.

Comparative Example 1 As a polyisocyanate, 43.6 parts of MDI was charged into a four-neck glass flask and kept at 50 ° C. Then, poly (ethylene adipate) (average molecular weight 1500, so that the molar ratio of isocyanate group / hydroxyl group is 2.6,
A transparent and viscous prepolymer A was obtained by reacting 100 parts of a hydroxyl value of 74.8) under a nitrogen stream while stirring at a temperature of 60 to 70 ° C for 3 hours. The NCO group content was 6.3%. Prepolymer A thus obtained
As the curing agent, 1,4-butanediol / trimethylolpropane / triethylenediamine (weight ratio: 6) was added so that the molar ratio of hydroxyl group / isocyanate group in the liquid was 0.90.
5.0 / 35.0 / 0.13) mixture B solution,
The / B mixed solution was stirred until it became completely transparent, and then defoaming was performed at a reduced pressure degree of a vacuum pump of 10 Torr or less until the foaming stopped. This A / B mixed solution was poured into a centrifugal molding machine preheated to 130 ° C, and primary curing was performed at 130 ° C for 1 hour. Physical properties and the like of the obtained plate-like polyurethane were measured in the same manner as in Example 1. The results are shown in Table 1.

[0022]

[Table 1]

The injection hardness (JIS A) in Table 1 was measured one day and one week after the completion of the secondary crosslinking. Further, the demolding time was set so that the molded product had no tackiness and could be easily removed from the mold at the primary curing temperature (130 ° C.). The physical property values are based on JIS K 6301. Further, as an evaluation method of the improvement of the change in physical properties due to the deviation of the stoichiometric value, the variation of hardness σ _n-1 (n = 1) after primary curing at 120 ° C. for 10 hours and after aging at room temperature for 24 hours.
The smaller one of 6) was judged as good.

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[Procedure amendment]

[Submission date] February 4, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

The polyester-type isocyanate-terminated prepolymer, which is the component (A) of the present invention, is prepared at an isocyanate group / hydroxyl group molar ratio of 3.0 to 95.5. The reaction between the polyisocyanate and the polyester polyol may be carried out by a conventional method, usually 50 to 100 ° C.
Reacted at temperatures prepolymer isocyanate terminated is obtained.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Comparative Example 1 As a polyisocyanate, 43.6 parts of MDI was charged into a four-neck glass flask and kept at 50 ° C. Then, poly (ethylene adipate) (average molecular weight 1500, so that the molar ratio of isocyanate group / hydroxyl group is 2.6,
A transparent and viscous prepolymer A was obtained by reacting 100 parts of a hydroxyl value of 74.8) under a nitrogen stream while stirring at a temperature of 60 to 70 ° C for 3 hours. The NCO group content was 6.3%. Prepolymer A thus obtained
As the curing agent, 1,4-butanediol / trimethylolpropane / triethylenediamine (weight ratio: 6) was added so that the molar ratio of hydroxyl group / isocyanate group in the liquid was 0.90.
5.0 / 35.0 / 0.13) mixture B solution,
The / B mixed solution was stirred until it became completely transparent, and then defoaming was performed at a reduced pressure degree of a vacuum pump of 10 Torr or less until the foaming stopped. This A / B mixed solution was poured into a centrifugal molding machine preheated to 130 ° C, and primary curing was performed at 130 ° C for 1 hour. The obtained plate-like polyurethane is heated at 120 ° C for 2 hours.
After secondary cross-linking for a while, aging at room temperature for 1 week
A urethane elastomer was obtained . The results are shown in Table 1.

Claims (1)

[Claims] 1. In a urethane elastomer, (A) a polyester-based isocyanate-terminated prepolymer and (B)
Weight mixing ratio A / B of polyester polyol, short chain glycol and short chain triol mixture is 100/45 to 10
A two-liquid injection type urethane elastomer composition having an excellent demolding property, which is 0/222.