JP4775751B2 - Thermoset urethane elastomer molding - Google Patents

Description

【００４１】
〔硬化剤の配合〕
合成実施例５〜８、合成比較例５〜８
表２に示す配合比で、１，４−ＢＤ、ＴＭＰ、各種ポリエステル、触媒を７５℃で１時間混合して、硬化剤を得た。配合割合を表２に示す。なお、合成比較例４は、ＴＨＥＩＣそのものを用いたが、７５℃では均一な液体にならなかったため、以後の評価を行わなかった。
【００４２】
【表２】

【００４３】
合成実施例１〜８、合成比較例１〜８、表１、２における原料の略記号等は以下の通り。

【００４４】
〔熱硬化ウレタンエラストマー成型物の製造〕
実施例１〜４、比較例１〜３
表３に示す組み合わせ、配合比で、あらかじめ８０℃に加温した主剤、及びあらかじめ８０℃に加温した硬化剤を配合して均一に混合した後、直ちに真空脱泡により脱気を行った。次いで、あらかじめ１３０℃に加温した２ｍｍ厚用平板シート金型に注型した。その後１３０℃で１時間硬化を行い成型物を得た。この成型物の物性測定結果を表３に示す。
【００４５】
硬度及び物性測定
２０℃及び６０℃の温度下で２時間養生し、速やかに恒温恒湿（２３℃、６０％）においてＪＩＳ Ｋ−７３１２に基づき測定を行った。
【００４６】
【表３】

【００４７】
表３において
ＨｓＡ：Ａ硬度
ＴＢ ：破断時強度
ＥＢ ：破断時伸び
ＴＲ ：引裂強度
【００４８】
表３より、本発明の熱硬化ウレタンエラストマー成型物は、高温時でも特に引裂強度を保っているものであった。一方、比較例の高温時の物性は、常温時のそれと比較すると、低下が大きいものであった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermosetting urethane elastomer molded product having a JIS A hardness of 60 to 90 and used for industrial equipment parts. In particular, the present invention relates to a thermosetting urethane elastomer molded product having a small decrease in mechanical properties even in a temperature atmosphere of 50 to 70 ° C.
[0002]
[Prior art]
Thermosetting urethane elastomers are widely used as industrial equipment parts because of their excellent productivity and mechanical properties. The thermosetting urethane elastomer is obtained from an isocyanate and a polyol. Examples of the isocyanate raw material include diphenylmethane diisocyanate (hereinafter abbreviated as MDI). Examples of the polyol raw material include a long-chain polyol and a short-chain polyol. Examples of the long-chain polyol include a polyester diol such as ethylene adipate, butylene adipate, and caprolactone, or a polyether diol such as polytetramethylene ether glycol. Examples of the short chain polyol include short chain diols such as 1,4-butanediol (hereinafter abbreviated as 1,4-BD) and short chain triols such as trimethylolpropane (hereinafter abbreviated as TMP).
[0003]
Thermosetting urethane elastomers are produced from these raw materials by the one-shot method in which all raw materials are reacted simultaneously, the prepolymer method in which a specific raw material is a prepolymer, the semi-one-shot method, etc., but the reaction control is easy. Therefore, a prepolymer method for curing an isocyanate (hereinafter abbreviated as NCO) group-terminated prepolymer with a hydroxyl group-containing curing agent and a semi-one-shot method are widely used.
[0004]
Thermosetting urethane elastomers used for conventional industrial equipment parts have large temperature dependence of physical properties. For example, the physical properties at low temperatures are significantly different from those at high temperatures, and the tensile strength is significantly reduced particularly at high temperatures, which makes it difficult to design industrial machines. In addition, the life of the parts was likely to be short. Furthermore, in terms of durability, it is currently impossible to further speed up industrial equipment.
[0005]
[Problems to be solved by the invention]
During high-speed operation or continuous operation, the thermosetting urethane elastomer itself has heat, which deteriorates physical properties and significantly deteriorates durability. For this reason, there has been a demand for the appearance of a thermosetting urethane elastomer molded product that suppresses deterioration of physical properties particularly at high temperatures and maintains design performance and improves durability.
[0006]
[Means for Solving the Problems]
By using a specific polyol as a raw material for thermosetting urethane elastomers, the present inventors can suppress deterioration of physical properties at high temperatures and maintain the performance and improve durability of thermosetting urethane elastomers used in industrial equipment parts. As a result, the present invention has been completed.
[0007]
That is, this invention is shown by the following (1)- (4) . (1) A thermosetting urethane elastomer molded product obtained by injecting a liquid material mixed with the main agent (A) and the curing agent (B) into a mold and curing it,
The main agent (A) contains an isocyanate group-terminated urethane prepolymer having an isocyanate content of 4.0 to 20.0% obtained by reacting diphenylmethane diisocyanate (A1) with an adipate-based polyester diol (A2),
The curing agent (B) contains an adipate-based polyester polyol (B1) obtained using tris (2-hydroxyethyl) isocyanurate, and the average number of functional groups is 2.01 to 3.00, Thermosetting urethane elastomer molding characterized by
[0008]
(2) The curing agent (B) is further ethylene glycol (EG), 1,2-propylene glycol (1,2-PG), 1,3-propylene glycol (1,3-PG) 1,3-butane 40 Diol (1,3-BD), 1,4-BD, Neopentyl glycol (NPG), 1,6-hexamethylene glycol (1,6-HG), 2,2-dimethylol heptane (DMH), 1, The group consisting of 4-cyclohexanediol (1,4-CHD), 1,4-cyclohexanedimethanol (1,4-CHDM), diethylene glycol (DEG), dipropylene glycol (DPG), bis (β-hydroxyethyl) benzene contain one or two or short chain diol following (B2) is more selective, thermoset urethane elastomer formed according to (1), wherein Thing.
[0009]
(3) The thermosetting urethane elastomer molded article according to (1) or (2) , wherein the curing agent (B) further contains an adipate polyester diol (A2).
[0010]
(4) The curing agent (B) further contains a kind of short-chain triol (B3) selected from the group consisting of trimethylolpropane, glycerin, hexanetriol, and trimethylolbutane , The thermosetting urethane elastomer molded product according to any one of 1) to (3).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a thermosetting urethane elastomer molded product obtained by injecting a liquid material in which a main agent (A) and a curing agent (B) are mixed into a mold and curing, and the main agent (A) is MDI (A1) and An adipate polyester comprising an NCO-terminated urethane prepolymer having an NCO content of 4.0 to 20.0% obtained by reacting an adipate polyester diol (A2), and a curing agent (B) obtained using THEIC It contains a polyol (B1). In the present invention, “short chain” means that the (number average) molecular weight is less than 500.
[0013]
The NCO group-terminated urethane prepolymer used in the present invention is obtained by reacting at least MDI (A1) with an adipate polyester diol (A2), and has an NCO content of 4.0 to 20.0%.
[0014]
Examples of MDI (A1) include various isomers, that is, 4,4′-MDI, 2,4′-MDI, 2,2′-MDI, and any mixture thereof. Liquid MDI (carbodiimidized MDI, uretoniminate MDI, etc.) can also be used. Preferred (A1) in the present invention is 4,4′-MDI.
[0015]
The number average molecular weight of the adipate-based polyester diol (A2) is 500 to 5,000, preferably 1,000 to 3,000. When the number average molecular weight is less than the lower limit, the resulting urethane prepolymer becomes cloudy and storage stability tends to be lowered. When the upper limit is exceeded, the viscosity of the urethane prepolymer becomes too high and casting tends to be difficult.
[0016]
Examples of the adipate-based polyester diol (A2) include ethylene glycol (EG), 1,2-propylene glycol (1,2-PG), 1,3-propylene glycol (1,3-PG) 1,3-butanediol ( 1,3-BD), 1,4-BD, neopentyl glycol (NPG), 1,6-hexamethylene glycol (1,6-HG), 2,2-dimethylol heptane (DMH), 1,4- Short chain diols such as cyclohexanediol (1,4-CHD), 1,4-cyclohexanedimethanol (1,4-CHDM), diethylene glycol (DEG), dipropylene glycol (DPG), bis (β-hydroxyethyl) benzene A polyester diol produced by polycondensation of one of the above and adipic acid, and two or more By short-chain diol and adipic acid polycondensation of, co is produced - including polyester diols, but is not limited thereto. If necessary, if the adipic acid is 50 mol% or more of the acid component, a dicarboxylic acid other than adipic acid, such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid , Malonic acid, glutaric acid, pimelic acid, suberic acid, curtaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutar Acid, α, β-diethylsuccinic acid, maleic acid, fumaric acid and the like can be used in combination. Preferred (A2) in the present invention is butylene adipate obtained from 1,4-BD and adipic acid.
[0017]
If necessary, in order to obtain an NCO group-terminated urethane prepolymer (A), raw materials other than the above MDI (A1) and adipate polyester diol (A2), for example, organic diisocyanates other than (A1), (A2 Polyester diols other than), polycarbonate diols, polyether diols, short chain diols as chain extenders, and the like. A polyol having an average functional group number exceeding 2 can also be used as long as the urethane prepolymer does not gel.
[0018]
The NCO group-terminated urethane prepolymer (A) used in the present invention is obtained by a known reaction, and is obtained, for example, by reacting at a reaction temperature of 20 to 100 ° C., preferably 50 to 80 ° C. for several hours. At this time, a urethanization catalyst can be used as needed. The reaction apparatus may be any apparatus as long as the above reaction can be achieved. Examples thereof include a mixing and kneading apparatus such as a reaction kettle or kneader with a stirrer, a uniaxial or multi-screw extrusion reaction apparatus, and batch reaction is possible. An apparatus is preferred.
[0019]
The NCO group-terminated urethane prepolymer (A) thus obtained has an NCO content of 4.0 to 20.0%, preferably 5.0 to 18.0%. When the NCO content is too small, the mechanical strength of the obtained molded product tends to be insufficient, and the viscosity of the prepolymer is often high, and the flowability of the mixed solution tends to be extremely deteriorated during casting. On the other hand, when the amount is too large, the molded product tends to be fragile, and the property stability at the time of storage and use is remarkably deteriorated, and the molding tends to be defective.
[0020]
The curing agent (B) used in the present invention is characterized by using an adipate-based polyester polyol (B1) obtained using at least tris (2-hydroxyethyl) isocyanurate (THEIC). When (B1) is used for the NCO group-terminated urethane prepolymer of the main agent (A), there is a problem of gelation when a sufficient amount is to be introduced. On the other hand, when the curing agent (B) is used, such a problem does not occur, and the amount of (B1) can be freely set according to the set physical properties of the obtained thermosetting urethane elastomer.
[0021]
(B1) is generally obtained by reacting adipic acid, THEIC, and a short-chain diol. Examples of the short-chain diol include those used in the above (A2). In addition, if adipic acid is 50 mol% or more of an acid component as needed, dicarboxylic acids other than adipic acid (refer to said reference) can be used together.
[0022]
(B1) can be obtained by (1) a one-step method in which adipic acid, THEIC, and a short-chain diol are reacted simultaneously, and (2) a polyester diol is synthesized by reacting adipic acid and a short-chain diol. And a two-stage method in which transesterification is carried out with THEIC.
[0023]
THEIC is a triol compound in which a hydroxyl group exists in an isocyanurate group having heat resistance via an ethylene group. TMP as a triol used in a conventional curing agent has a particularly low tear strength at high temperatures. In TMP, a quaternary carbon has a branched structure, one having an ethyl group and the other three having a methylol group. For this reason, since the bond energy is small and the flexibility is insufficient, the toughness is insufficient, and the tear strength at high temperature is considered to be small. In the present invention, there is a six-membered ring structure in which hydroxyl groups exist in three symmetric directions and the strain is small, and since this six-membered ring is a heat-resistant isocyanurate ring, the THEIC is used. The tear strength at is large.
[0024]
THEIC has a high melting point of 120 ° C. or higher. In JP-A-8-134170, THEIC is used as it is as a curing agent, so that it is necessary to increase the curing agent temperature at the time of blending. For this reason, the molding temperature is inevitably high, and an unnecessary heat history is given to the molded product. In the present invention, since the THEIC is introduced into the adipate polyester, the melting point is lowered to 60 to 100 ° C., and an unnecessary heat history is not given to the molded product.
[0025]
The average functional group number of (B1) is preferably 2.01 to 5.0, and particularly preferably 2.1 to 3.0. Further, the number average molecular weight of (B1) is preferably 500 to 3,000, and the number average molecular weight of 650 to 2,000 is particularly preferable.
[0026]
In the present invention, the short-chain diol (B2), the short-chain triol (B3), and the adipate polyester diol (A2) can be used in combination with the curing agent (B) as necessary. In particular, when (B2) is used in combination, the molded product can have strength.
[0027]
Examples of the short-chain diol (B2) include those used in (A2). In the present invention, 1,4-BD is preferred.
[0028]
Examples of the short chain triol (B3) include TMP, glycerin, hexanetriol, and trimethylolbutane. In the present invention, TMP is preferred.
[0029]
Examples of (A2) used for the curing agent (B) include those used for obtaining (A).
[0030]
The average functional group number of the curing agent (B) is 2.01 to 3.00 . When the average number of functional groups of the curing agent (B) exceeds 3.0, the crosslink density of the thermosetting urethane elastomer itself increases more than necessary, resulting in brittleness and a significant decrease in tensile properties.
[0031]
In the present invention, if necessary, polyols, dyes, pigments, fillers, antioxidants, defoaming agents, ultraviolet absorbers, reaction modifiers, foaming agents, antibacterial agents, antifungal agents, etc. Additives can be used. These additives are added to the main agent (A) and / or the curing agent (B) in consideration of stability, mixing properties, and the like.
[0032]
As a specific manufacturing procedure of the thermosetting urethane elastomer molding of the present invention, the above-mentioned raw materials and molding dies are used, for example, as follows.
1. The main agent (A) and the curing agent (B) that have been liquefied or reduced in viscosity by heating in advance are mixed uniformly (mixing). The NCO group / hydroxyl group (molar ratio) at this time is preferably 0.6 to 1.4, and particularly preferably 0.7 to 1.3. In addition, when (A2) is used for the curing agent (B), the mass ratio in the blending of the main agent (A) and the curing agent (B) can be (A) :( B) = 1: 1.
2. During mixing, the entrained air is removed (deaeration). A depressurization pump is usually used for deaeration.
3. The liquid is poured into a preheated mold (casting). The preheating temperature of the mold is about 60 to 200 ° C.
4). Heat to cause a curing reaction (curing). The curing temperature is about 60 to 200 ° C.
The curing time is about 2 to 60 minutes.
5. It is kept heated for a while, and after the poured liquid is cured and sufficiently strong, the cured product is removed from the mold (demolding).
6). Further heating is performed as necessary to further cure the molded product (post-curing).
[0033]
【The invention's effect】
As described above, since the thermosetting urethane elastomer of the present invention uses an adipate-based polyester polyol having THEIC as a curing agent, the deterioration of mechanical properties at high temperatures is smaller than that of conventional thermosetting urethane elastomers. It was. In particular, since the tensile properties under conditions of 50 to 70 ° C. have been improved, the durability of industrial equipment parts using thermosetting urethane elastomers has been improved. According to the present invention, it is possible to provide a thermosetting urethane elastomer part that can be used as an industrial machine part that is speeded up.
[0034]
【Example】
The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. In Examples and Comparative Examples, “%” means “% by mass”.
[0035]
[Synthesis of adipate-based polyester polyol using THEIC]
Synthesis example 1
In a reactor equipped with a stirrer, a cooling pipe, and a nitrogen introduction pipe, 502 g of adipic acid (AA), 250 g of 1,4-butanediol (1,4-BD), tris (2-hydroxyethyl) isocyanurate (THEIC) 348 g was charged and subjected to dehydration reaction at 180 to 190 ° C. under normal pressure. When the distilling rate of water became slow, 0.01 g of tetrabutyl titanate (TBT) was charged, and the reaction was further continued by starting the pressure reduction while further heating. The heating rate was 1 ° C./min and the temperature eventually reached 220 ° C. Moreover, pressure reduction was performed gradually and finally to 0.3 kPa. The reaction was terminated when no more water came out.
The appearance of the obtained polyester polyol (PBTA-1500) is solid at normal temperature, uniform transparent liquid at 75 ° C., hydroxyl value is 146.4 mgKOH / g, acid value is 3.2 mgKOH / g, number average molecular weight is 1, The average functional group number was 500.
[0036]
Synthesis example 2
In a reactor similar to that of Synthesis Example 1, 416 g of AA and 602 g of 1,4-BD were charged and subjected to dehydration reaction at 180 to 190 ° C. under normal pressure. When the distilling rate of water became slow, 0.01 g of tetrabutyl titanate (TBT) was charged, and the reaction was further continued by starting the pressure reduction while further heating. The heating rate was 1 ° C./min and the temperature eventually reached 220 ° C. Moreover, pressure reduction was performed gradually and finally to 0.3 kPa. The reaction was once terminated when water no longer came out. Next, 130 g of THEIC was charged and subjected to transesterification at 180 ° C. for 2 hours.
The appearance of the obtained polyester polyol (PBTA-1000) is solid at normal temperature, uniform transparent liquid at 75 ° C., hydroxyl value is 140.0 mgKOH / g, acid value is 0.3 mgKOH / g, number average molecular weight is 1, 000 and the average number of functional groups was 2.5.
[0037]
The number of average functional groups was calculated by measuring the number average molecular weight of the obtained polyester polyol by gel permeation chromatography (GPC) and using the number average molecular weight and the number of terminal groups determined from the hydroxyl value and acid value.
[0038]
[Synthesis of NCO group-terminated urethane prepolymer]
Synthesis Examples 1 to 4 and Synthesis Comparative Examples 1 to 3
MDI and various polyester polyols were mixed at the compounding ratio shown in Table 1, and reacted at 75 ° C. for 3 hours to obtain various NCO group-terminated prepolymers. The results are shown in Table 1.
[0039]
Synthesis Comparative Example 4
MDI and PBTA-1000 were mixed at the blending ratio shown in Table 1, and the reaction was started at 75 ° C. However, since a gelled product was generated during the reaction, the reaction was stopped.
[0040]
[Table 1]

[0041]
[Composition of curing agent]
Synthesis Examples 5-8, Synthesis Comparative Examples 5-8
1,4-BD, TMP, various polyesters, and a catalyst were mixed at 75 ° C. for 1 hour at a blending ratio shown in Table 2 to obtain a curing agent. The blending ratio is shown in Table 2. In Synthesis Comparative Example 4, THEIC itself was used, but since it did not become a uniform liquid at 75 ° C., subsequent evaluation was not performed.
[0042]
[Table 2]

[0043]
Synthetic Examples 1 to 8, Synthetic Comparative Examples 1 to 8, and abbreviations of raw materials in Tables 1 and 2 are as follows.

[0044]
[Manufacture of thermoset urethane elastomer moldings]
Examples 1-4, Comparative Examples 1-3
After mixing and uniformly mixing the main agent preliminarily heated to 80 ° C. and the curing agent preliminarily heated to 80 ° C. with the combinations and mixing ratios shown in Table 3, deaeration was performed immediately by vacuum defoaming. Then, it was cast into a 2 mm thick flat sheet metal mold preheated to 130 ° C. Thereafter, curing was performed at 130 ° C. for 1 hour to obtain a molded product. Table 3 shows the physical property measurement results of this molded product.
[0045]
Hardness and physical property measurements Cured for 2 hours at temperatures of 20 ° C. and 60 ° C., and quickly measured according to JIS K-7312 at constant temperature and humidity (23 ° C., 60%).
[0046]
[Table 3]

[0047]
In Table 3, HsA: A hardness TB: strength at break EB: elongation at break TR: tear strength
From Table 3, the thermosetting urethane elastomer molded product of the present invention maintained particularly tear strength even at high temperatures. On the other hand, the physical properties at high temperatures of the comparative examples were greatly reduced compared to those at normal temperatures.

Claims (4)

A thermosetting urethane elastomer molded product obtained by injecting a liquid material mixed with the main agent (A) and the curing agent (B) into a mold and curing it,
The main agent (A) contains an isocyanate group-terminated urethane prepolymer having an isocyanate content of 4.0 to 20.0% obtained by reacting diphenylmethane diisocyanate (A1) with an adipate-based polyester diol (A2),
The curing agent (B) contains an adipate-based polyester polyol (B1) obtained using tris (2-hydroxyethyl) isocyanurate, and the average number of functional groups is 2.01 to 3.00, Thermosetting urethane elastomer molding characterized by The curing agent (B) further comprises ethylene glycol (EG), 1,2-propylene glycol (1,2-PG), 1,3-propylene glycol (1,3-PG) 1,3-butane 40 diol (1 , 3-BD), 1,4-BD, neopentyl glycol (NPG), 1,6-hexamethylene glycol (1,6-HG), 2,2-dimethylol heptane (DMH), 1,4-cyclohexane Selected from the group consisting of diol (1,4-CHD), 1,4-cyclohexanedimethanol (1,4-CHDM), diethylene glycol (DEG), dipropylene glycol (DPG), and bis (β-hydroxyethyl) benzene. that one or to contain two short chain diol following (B2), thermoset urethane elastomer molded article according to claim 1, wherein the.  The thermosetting urethane elastomer molding according to claim 1 or 2, wherein the curing agent (B) further contains an adipate-based polyester diol (A2). The hardener (B) further contains a kind of short chain triol (B3) selected from the group consisting of trimethylolpropane, glycerin, hexanetriol, and trimethylolbutane. The thermosetting urethane elastomer molding of any one of these.