JP2002265550A - Heat-cured urethane elastomer molding having excellent properties at high temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-cured urethane elastomer molding for the parts of industrial equipment which has excellent properties of tensile strength especially at a condition of 50-70 deg.C. SOLUTION: The heat-cured urethane elastomer molding is obtained by injecting to cure a liquid mixture of (A) an NCO-terminal urethane prepolymer and (B) an OH-terminal curing agent into a mold and then removing from the mold, and (B) the OH-terminal curing agent contains (B1) a compound represented by formula (1) as one of the components. In the formula (1), [R1 , R2 and R3 may be mutually all the same or different, and one or two of them may be hydrogen(s), but at least one is an alkyl group having a carbon number of 1 or more].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting urethane elastomer molded article used for industrial equipment parts, and more particularly to a thermosetting urethane characterized by having excellent tensile properties at 50 to 70.degree. It relates to an elastomer molding.

[0002]

2. Description of the Related Art Generally, industrial equipment parts made of cast urethane elastomer are used as a raw material for isocyanate as diphenylmethane diisocyanate (hereinafter abbreviated as MDI).
Polyol diol such as polyethylene adipate, polybutylene adipate, polycaprolactone, or polytetramethylene ether glycol, or the like,
If necessary, 1,4-butanediol (hereinafter abbreviated as 1,4-BD), trimethylolpropane (hereinafter abbreviated as TMP), a mixture thereof, or the like may be used as a short-chain diol raw material. A technique in which a polyurethane elastomer obtained by a shot method, a prepolymer method, or the like is used for industrial equipment parts is used. In order to easily control the reaction, an isocyanate group (hereinafter abbreviated as NCO) terminal prepolymer is converted to a hydroxyl group (hereinafter, OH). A method of curing with a terminal curing agent is widely used.

In the prior art, thermosetting urethane elastomers used for industrial machine parts have a large temperature dependency, and the elastomer properties at low and high temperatures are significantly different. At present, it is difficult to design machines. In general, when the temperature of a part of an industrial machine becomes high during high-speed operation and continuous operation, the physical property is reduced, and the performance as an industrial machine part is not satisfied, or the part is easily damaged. For this reason, the durability of the industrial machine parts was inferior and the life of the parts was short. Further, at present, it is impossible to further increase the speed of industrial machines in terms of durability.

A technique using tris (2-hydroxyethyl) isocyanurate having an isocyanurate ring structure (hereinafter abbreviated as THEIC) as a curing agent is disclosed in Japanese Unexamined Patent Application Publication No. Hei 8 (1996).
-134170. This technology is
It is said that it has an effect that a drastically short in-mold crosslinking time can be obtained without affecting the physical properties.

However, the THEIC has a melting point of 131 ° C. and has poor solubility in low molecular weight polyols. Therefore, as described in Examples of this publication, a crosslinking agent (corresponding to a curing agent in the present application) is used. ) Had to be raised to 150 ° C., and there was a problem in handling and safety.
The publication does not disclose or suggest the tensile properties at high temperatures.

[0006]

The heat-curable urethane elastomer component itself has heat during high-speed operation or continuous operation, and its physical properties are deteriorated. In particular, by suppressing the deterioration of the physical properties of the elastomer at a high temperature, the design performance is maintained and the durability is improved.

[0007]

Means for Solving the Problems The present inventors have found that in a thermosetting urethane elastomer molded article as an industrial equipment part, a molded article using a curing agent containing a specific compound can maintain the performance of an industrial machine part. They found that the durability was improved, and completed the present invention.

That is, according to the present invention, a liquid material obtained by mixing an NCO-terminated urethane prepolymer (A) and an OH-terminal curing agent (B) is poured into a mold and cured, and then the heat obtained by removing the cured product is obtained. A thermosetting urethane elastomer molding excellent in high-temperature characteristics, characterized in that the cured urethane elastomer molding contains a compound (B1) represented by the following general formula (1) as one component of the OH terminal curing agent (B). Things.

[0009]

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[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a liquid material obtained by mixing an NCO-terminated urethane prepolymer (A) and an OH-terminal curing agent (B) is poured into a mold and cured, and then the cured product is demolded. In the obtained thermosetting urethane elastomer molded product, as a component of the OH terminal curing agent (B), a compound (B1) represented by the following general formula (1) (hereinafter, alkyl-substituted T)
HEIC).

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The alkyl substituent of the alkyl-substituted THEIC is preferably a methyl group or an ethyl group. When the alkyl group is larger than the propyl group, the hardness of the obtained elastomer is reduced, and the effect as a curing agent is relatively small. The alkyl substituent is preferred because one kind is easily available. Further, at least one of R ₁ , R ₂ , and R ₃ may be substituted with an alkyl group. However, when the number of substitution is reduced, the effects of the present invention such as an increase in melting point and a decrease in compatibility with other polyols are reduced. . Therefore, it is preferable that all three are substituted.

When all R are hydrogen, they have a THEIC, have high crystallinity, and are not suitable as OH-terminal curing agents. In order to dissolve, heating must be performed at about 140 ° C., so that other curing agent components may cause decomposition, exchange reaction, etc., and may not function as a curing agent.

The NCO-terminated prepolymer (A) used in the present invention comprises at least MDI (A1) and an OH-terminated compound (A) of a polyol having a number average molecular weight of 500 to 5,000.
It is preferably obtained by the reaction with 2).

The NCO content of the NCO-terminated prepolymer is preferably 5 to 25% by mass. When the NCO content is lower than 5%, the viscosity of the prepolymer mainly increases,
The flowability of the urethane resin during casting is significantly reduced. 25
%, The property stability during storage and during use becomes extremely poor, and it becomes difficult to obtain stable industrial equipment parts.
It is not suitable for industrial equipment parts because of problems such as poor molding.

The MDI (A1) includes various isomers, that is, 4,4'-MDI, 2,4'-MDI,
2,2'-MDI and any mixture thereof. In addition, liquid MDI (carbodiimidated MDI, uretoniminated MDI, etc.) can also be used.

The OH-terminated polyol (A2) includes polyether polyols and polyester polyols. Examples of the polyether polyol include poly (ethylene ether) glycol, poly (propylene ether) glycol and poly (tetramethylene ether) glycol (hereinafter abbreviated as PTMG) and cyclic ethers such as ethylene oxide, propylene oxide, trimethylene oxide and Of tetrahydrofuran,
Aliphatic diols such as ethylene glycol, 1,3-butanediol, 1,4-BD, diethylene glycol,
Dipropylene glycol, 1,2-propylene glycol and 1,3-propylene glycol as initiators,
It is a polyether produced. Further, a mixture of the above-mentioned polyethers can also be used.

Examples of the polyester polyol include polyols obtained by polycondensation of a polybasic acid and a polyhydric alcohol. For example, poly (ethylene adipate) diol, poly (propylene adipate) diol, poly (ethylene-propylene adipate) diol, poly (butylene adipate) diol, poly (hexamethylene adipate) diol, etc., ethylene glycol, propylene glycol, adipic acid Copolyester diols produced by polycondensation, such as poly (1,4-butylene-ethylene adipate) diol, poly (1,4-butylene-propylene adipate) diol, and poly (1,4-butylene-ethylene) -Propylene adipate) diol, but is not limited thereto. Further, polycaprolactone polyol or the like obtained by ring-opening polymerization of a lactone ring can also be used. Further examples of other polyester diols include caprolactone and / or dicarboxylic acids such as succinic acid, malonic acid, pimelic acid, sebacic acid and suberic acid, such as diols such as ethylene glycol,
1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2
-Ethyl-2-butyl-1,3-propanediol,
Also included are those produced by polycondensation with 1,4-BD, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, and the like. Also, mixtures of the above polyesters can be used. Polyester polyol and PTMG are preferred polyols because of their compatibility with the crosslinking agent.

The NCO-terminated prepolymer (A) used in the present invention is prepared by reacting MDI (A1) with a polyol (A2) and, if necessary, a chain extender at a reaction temperature of 50 to 100 ° C.
Reaction time: obtained by a production method under reaction conditions of 1 to 5 hours.

The OH-terminal curing agent (B) used in the present invention comprises:
Other than the alkyl-substituted THEIC (B1), those using a diol (B2) having a number average molecular weight of 300 or less and a triol (B3) having a number average molecular weight of 500 or less are preferable. Further, those further added with a bifunctional polyol (B4) having a number average molecular weight of 500 to 5,000 are also preferable.

As short-chain diols (B2) having a number average molecular weight of 300 or less, ethylene glycol, diethylene glycol, propylene glycol, 1,4-BD, 1,3
-Butanediol, 1,6-hexanediol, neopentyl glycol, hydrogenated bisphenol A and the like. In the present invention, 1,4-BD is particularly preferred.

Examples of the short-chain triol (B3) having a number average molecular weight of 500 or less include glycerin, TMP, hexanetriol and the like. In the present invention, TMP is particularly preferred.

As the OH-terminated polyol (B4) having a number average molecular weight of 500 to 3,000, those described in the above (A2) can be used.

The preferred OH-terminal curing agent in the present invention is an alkyl-substituted THEIC (B1), a short chain diol (B2) and a short chain triol (B3) having a mass ratio of 10 to 70/70.
It is in the range of 30 to 80/0 to 30. In addition, short-chain polyols (alkyl-substituted THEIC and short-chain diols,
The mass ratio of the short chain triol to the OH-terminated polyol is in the range of 100/0 to 5/95.

The concrete production procedure of the urethane elastomer molded product for industrial equipment parts of the present invention is produced by using the above-mentioned raw materials and a molding die, for example, as follows. 1. The NCO-terminated prepolymer (A) and the OH-terminated hardener (B) are uniformly mixed, and the entrapped air is released. 2. The liquid is poured into the preheated mold (casting), and a curing reaction is performed by heating. The temperature at this time is 60 to 200
It is about ° C. 3. After being left in a heated state for a while, when the poured liquid is cured, the cured product is removed from the mold (demolding). 4. If desired, the molded product after demolding may be post-heated.

In the present invention, an antioxidant, a defoaming agent, a UV absorber, a reaction regulator and the like can be used as additives as required.

[0026]

According to the present invention, a molded article of a thermosetting urethane elastomer for industrial equipment parts contains an alkyl-substituted THEIC (B1) as a component of the OH-terminal curing agent (B) to reduce the deterioration in physical properties at high temperatures. By improving the tensile properties particularly at 50 to 70 ° C., the durability of the cast urethane elastomer for industrial equipment parts was improved. As industrial machines increase in speed, the amount of energy applied to components increases with the increase in speed, and the components themselves tend to have heat. Therefore, at present, it is desired to maintain physical properties at high temperatures.

[0027]

EXAMPLES The present invention will be described by way of Examples and Comparative Examples.
Although described in more detail, the present invention is not limited by these. In Examples and Comparative Examples,
All "parts" mean "parts by mass", and all "%" mean "% by mass".

[Synthesis of Prepolymer] MDI and various polyols were mixed at the compounding ratios shown in Tables 1 and 2 at 75 ° C.
For 3 hours to obtain various NCO-terminated prepolymers. Table 1 shows the results.

Examples 1 to 3 [Blending of curing agent and addition of catalyst]
After 1,4-BD, TMP, alkyl-substituted THEIC, and various polyols were mixed at 75 ° C. for 1 hour, the amount of the triethylenediamine catalyst shown in Table 1 was added to the mixture of the curing agent.

COMPARATIVE EXAMPLE 1 50 parts of 1,4-BD and 50 parts of THEIC were added.
Heating to 5 ° C. and stirring was attempted, but the THEIC was not completely melted and did not become a uniform curing agent. Further, the temperature was raised to 110 ° C., but the same was found. Therefore, the reaction with the isocyanate was not performed.

Comparative Example 2 7.5 parts of 1,4-BD and 3.0 parts of TMP
3.5 parts of C was added, and the mixture was heated to 75 ° C. and stirring was attempted. Further, the temperature was raised to 110 ° C., but the same was found. Therefore, the reaction with the isocyanate was not performed.

Comparative Examples 3 to 5 [Blending of curing agent and addition of catalyst]
1,4-BD, TMP, alkyl-substituted THEIC (B
1) After mixing various polyols at 75 ° C. for 1 hour, the amount of the triethylenediamine catalyst shown in Table 2 was added to this curing agent mixture.

Measurement of hardness and tensile properties Cured at 20 ° C. and 60 ° C. for 2 hours and immediately JIS-K7312 at constant temperature and humidity (23 ° C., 60%).
The measurement was performed based on.

[0034]

[Table 1]

[0035]

[Table 2]

In Tables 1 and 2, the abbreviations of the raw materials are as follows. MDI: 4,4'-diphenylmethane diisocyanate EA-2000: Polyesterdiol obtained from ethylene glycol and adipic acid Number average molecular weight = 2,000 BA-2000: Number of polyesterdiol obtained from 1,4-BD and adipic acid Average molecular weight = 2,000 PTMG-2000: poly (tetramethylene ether) glycol Number average molecular weight = 2,000 Me-THEIC: THEIC in which all substituents are methyl groups Et-THEIC: THEIC in which all substituent groups are ethyl groups

[0037]

Industrial Applicability The present invention relates to a molded product of a thermosetting urethane elastomer for parts for industrial equipment, wherein an alkyl-substituted THEIC (B) is used as one component of the OH terminal curing agent (B).
By containing 1), it is possible to prevent a decrease in physical properties at a high temperature, and in particular, by improving the tensile physical properties under a condition of 50 to 70 ° C, the durability of cast urethane elastomer for industrial equipment parts is improved. Led to improvement.
With the increase in speed of industrial machines, the amount of energy applied to components increases, and the components themselves tend to have heat. For this reason, at present, it is desired to maintain physical properties at high temperatures. According to the present invention, it has become possible to provide a thermosetting urethane elastomer component that can be used as a high-speed industrial machine component.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C08L 75:04 C08L 75:04 F term (reference) 4F071 AA53 BB01 BC07 4F204 AA42 EA03 EB01 EF01 EF02 EF27 EK17 EW01 EW06 4J034 CA05 CB04 CC35 CC62 CC65 JA42

Claims (1)

[Claims] 1. A thermosetting composition obtained by injecting a liquid material obtained by mixing an isocyanate group-terminated urethane prepolymer (A) and a hydroxyl group-terminated curing agent (B) into a mold, curing the cured product, and then removing the cured product. In urethane elastomer moldings,
A thermosetting urethane elastomer molded article having excellent high-temperature properties, comprising a compound (B1) represented by the following general formula (1) as one component of a hydroxyl group terminal curing agent (B). Embedded image