JPS6058247B2 - Polyurethane reaction injection molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding polyurethane elastomers or microcellular polyurethane elastomers by a reaction injection method, and in particular, a method for molding polyurethane elastomers or microcellular polyurethane elastomers by reacting a specific polyol compound with a polyisocyanate compound. The present invention relates to a reaction injection molding method for obtaining polyurethane elastomers.

It is known to mold polyurethane elastomers and microcellular polyurethane elastomers by reaction injection molding methods. For example, energy-absorbing bumpers for automobiles are molded using this method. The raw materials for these polyurethanes are mainly polyisocyanate compounds and polyol compounds. The reaction injection molding method usually involves pressurizing two liquids each containing these two main components, collision-mixing the two liquids with a mixing injection machine, and then filling the mixture into a mold to harden the molded product. Refers to the method of extracting. Reaction injection molding is called RIM (Reaction Injection M).
Hereafter, reaction injection molding is referred to as RIM.
It is called. The RIM method is mainly used for molding urethane elastomers and microcellular urethane elastomers.

Hereinafter, both will be referred to as urethane elastomers unless otherwise specified. As mentioned above, one of the main raw materials for the urethane elastomer is a polyol compound. Polyether polyols and polyester polyols are known as polyether compounds used for molding urethane elastomers by the RIM method, but polyether polyols are mainly used, especially polyoxyalkylene polyols. be. Polyoxyalkylene polyols are usually produced by adding alkylene oxides such as propylene oxide and ethylene oxide to an initiator having active hydrogen such as polyhydric alcohols and amines. However, polyurethane elastomers obtained by the RIM method using conventional polyoxyalkylene polyols have not always been satisfactory in terms of physical properties. In particular, one of the problems was that the rate of change in bending modulus (modulus of elasticity) with temperature was large. In molding a polyurethane elastomer by the R1M method, the present inventor conducted studies from the aspect of polyoxyalkylene polyol in order to reduce the temperature dependence of the bending modulus of the polyurethane elastomer.

As a result, it was discovered that by using a polyoxyalkylene polyol obtained by adding an alkylene oxide containing butylene oxide to a polyhydroxy compound, it was possible to reduce the temperature dependence of the bending modulus of a polyurethane elastomer obtained by the R1M method. Ta. This is the gist of the present invention, namely:
Mixing and forming at least two pressurized liquid streams, a pressurized liquid stream based on a polyisocyanate compound and a pressurized liquid stream based on a polyol compound. In a method of molding a polyurethane elastomer or a microcellular polyurethane elastomer by injection into a mold, at least one of the polyol compounds is a polyhydroxy compound containing butylene oxide and an alkylene oxide other than butylene oxide (however, at least a portion thereof is ethylene oxide). It is characterized by being a polyoxyalkylene polyol obtained by adding , an oxybutylene group content of 20 to 7% by weight, a terminal oxyethylene group content of 10 to 25% by weight, and a hydroxyl value of 20 to 45K0HTn9/g. This is a reaction injection molding method for polyurethane. The polyoxyalkylene polyol in the present invention is produced by addition polymerizing an alkylene oxide containing 1,2-butylene oxide to an initiator made of a polyhydroxy compound.

As the polyhydroxy compound, polyhydric alcohols, alkanolamines, polyhydric phenols, and other compounds having two or more hydroxyl groups can be used.

Particularly preferred are ethylene glycol, propylene glycol, butylene glycol, other dihydric alcohols, glycerin, trimethylolpropane, other trihydric alcohols, pentaerythritol, diglycerin, and other tetrahydric alcohols. These di- to tetrahydric alcohols can be used alone, or in mixtures thereof, or in combination with other polyhydroxy compounds. The above initiator undergoes addition polymerization of alkylene oxide in the presence of a catalyst such as an alkali metal hydroxide.

The alkylene oxide must be an alkylene oxide containing at least butylene oxide, and at least a portion of the other alkylene oxide must be ethylene oxide. All or part of the ethylene oxide needs to be added last. As a result, an oxyethylene group is introduced at the end of the polyoxyalkylene polyol. As the alkylene oxide except for the ethylene oxide introduced at the terminal, butylene oxide alone or a combination of butylene oxide and another alkylene oxide is used. In the latter case, propylene oxide or ethylene oxide is preferred as the other alkylene oxide, with propylene oxide being particularly preferred. When combining this butylene oxide with other alkylene oxides, they can be added sequentially or in a mixed manner, or they can be added in combination. Further, as other alkylene oxides, alkylene oxides other than propylene oxide or ethylene oxide, and compounds containing epoxy groups can also be used. For example, epichlorohydrin,
Examples include styrene oxide, glycidyl ether compounds, etc. In addition, as butylene oxide, the above-mentioned 1, 2
In addition to -butylene oxide, 2,3-butylene oxide can also be used. The polyoxyalkylene polyol in the present invention contains 20 to 7 weight% of oxybutylene chains.
, a polyoxyalkylene polyol containing 10 to 25% by weight of terminal oxyethylene chains and having a hydroxyl value (OH value) of 20 to 45K0Hm9/g.

1 of all hydroxyl groups in this polyoxyalkylene polyol
The proportion of class hydroxyl groups is preferably 70 to 80%, and the number of hydroxyl groups is preferably 2 to 4. Although it may have an oxyethylene group other than at the terminal end, preferably the oxyethylene group exists substantially only at the terminal end. Preferably, the number of hydroxyl groups is 2 (ie, diol), 3 (ie, triol), and mixtures thereof. The molecular weight of the polyoxyalkylene polyol is preferably 3,000 to 8,000. Invention RI
The liquid containing a polyol compound as a main component in Method M may contain various compounds in addition to the polyoxyalkylene polyol described above.

Compounds that are usually considered essential are crosslinking agents and catalysts.
The crosslinking agent is a compound having at least two active hydrogens and having a relatively low molecular weight. For example, ethylene glycol, 1,4-butanediol, alkanolamine,
Examples include low molecular weight polyether polyols, catechol, other hydroxyl group-containing compounds, aromatic diamines, ethylene diamine, and other amines. Particularly preferred are ethylene glycol, 1,4-butanediol, 2,3-butanediol, propylene glycol, and other dihydric alcohols. As the catalyst, amines such as triethylene diamine and organometallic compounds such as dibutyltin dilaurate are mainly used. Furthermore, in the case of microcellular polyurethane elastomers, blowing agents are used. Suitable blowing agents include water, fluorotrichloromethane, difluorodichloromethane, methylene chloride, and other halogenated hydrocarbons. Furthermore, the liquid containing a polyol compound as a main component contains the polio in the present invention. Polyol compounds other than xyalkylene polyols may also be included, such as other polyether polyols, polymer polyols, polyester polyols, and the like. However, in that case, it is preferable to use a mixture containing the polyoxyalkylene polyol of the present invention in an amount of 5% by weight or more in the total polyol compound. Furthermore, the liquid containing the polyol compound as a main component may contain fillers such as powder fillers, fibrous fillers, and flat fillers, colorants, stabilizers, and other additives. In addition to the polyisocyanate compound, the liquid containing the polyisocyanate compound as a main component may contain additives that do not substantially react with the polyisocyanate compound, such as blowing agents such as halogenated hydrocarbons and the above-mentioned fillers. , usually the polyisocyanate compound alone is used.

As the polyisocyanate compound, TDI. ．． MDI
Although polyphenylmethane polyisocyanate, xylylene diisocyanate, hexamethylene isocyanate, naphthalene diisocyanate, and other compounds having two or more isocyanate groups can be used, aromatic polyisocyanate compounds are particularly preferred. These isocyanate compounds can also be modified and used as modified isocyanate compounds having carbodiimide groups, urethane groups, urea groups, allophanate groups, biuret groups, isocyanurate groups, and the like. In the RIM method, at least two liquids are pressurized and the pressurized liquid flows are mixed and injected into a mold to perform molding.

Normally, the above two liquids are used, but there are methods in which at least one of these liquids is divided into two or more, and a method in which a fluidizable component whose main component is another component (for example, a filler) is used. There are also cases where three or more components are mixed, such as a method where three components are used. There are various methods for mixing at least two pressurized liquid streams, but the most common method is collision mixing. Various types of mixing injection devices are known.
There are devices described in Japanese Patent Application Laid-open No. 9-21465 and Japanese Patent Application Laid-open No. 125576/1983. The polyurethane elastomer obtained by the present invention is characterized by low temperature dependence of bending modulus.

The temperature dependence of the bending modulus is determined, for example, by ASTM D7
It can be measured by the method specified in 9O. That is,
The ratio of the bending modulus at -30°C to the bending modulus at 70°C (hereinafter referred to as the modulus ratio) [-3
0°C/70°C], the value generally decreases as the proportion of oxybutylene chains increases. Therefore, if we focus only on the modulus ratio, the higher the proportion of oxybutylene chains, the better; however, if we consider other physical properties and polyurethane production reactions, the appropriate proportion is 20 to 7% by weight. It is. EXAMPLES The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited only to these Examples.

Reference Example 1 750 g of glycerin subjected to addition polymerization of propylene oxide using caustic potash as a catalyst to give a molecular weight of 870 and 9.5 g of caustic power were mixed, and the mixture was heated to 120°C.

After dehydrating the moisture on the catalyst under reduced pressure, 1650 g of propylene oxide was added to the autoclave at an internal pressure of 2.8.
The cells were introduced for 5.1 hours while maintaining k9/CllG. Thereafter, aging was performed at 120°C for 2 hours. Subsequently, 740 g of 1,2-butylene oxide was introduced into the autoclave over a period of about 2 hours, and the autoclave was further aged for 2 hours. Further, 550 g of ethylene oxide was charged over a period of 2 hours, and the three-powder reaction was continued. After the reaction was completed, 175 g of magnesium silicate was added, stirred at 130° C. for 3 hours to adsorb the catalyst, filtered and dried to obtain a polyol. The 0H value of the obtained product is 34.2K0HTrL9/g, and the viscosity is 79■P/2.
5° C. and contains about 2% filtrate of 1,2-butylene oxide. Comparative example 1 of reference example (polyol not using butylene oxide) Reference example -
In the same manner as in 1, 2390 g of propylene oxide was added to 6.5
The introduction was carried out at 120° C. over a period of time.

Thereafter, aging was performed at 120°C for 2 hours. followed by 55
0 g of ethylene oxide was introduced into the autoclave over 2 hours and the reaction continued for 3 minutes. The product obtained by purification had an OH number of 33.9K0Hm9/g1 and a viscosity of 840CP/25°C.

Reference Example 2 Polyol 7 with a molecular weight of 870 obtained by adding propylene oxide to glycerin in the same manner as in Reference Example-1
After mixing 50 g of caustic acid with 9.5 g of caustic acid per month as a catalyst, the temperature was raised to 120°C.

After removing moisture under reduced pressure, 2390 g of 1,2-butylene oxide was introduced into the autoclave over 43 hours. After aging at 120℃ for 2 hours, 550℃
g of ethylene oxide was introduced into the autoclave over 2 hours and the reaction continued for 3 minutes.

The product obtained by purification has an OH number of 34.1K0Hm9/g1 and a viscosity of 820CP/25°C, and contains about 65% by weight of 1,2-butylene oxide.

Reference Example 3 After mixing 450 g of propylene glycol with a molecular weight of 500 obtained by addition polymerizing propylene oxide using caustic potash as a catalyst and 23.5 g of caustic potash,
The temperature was raised to 110°C.

After removing water under reduced pressure, propylene oxide 2
000g, autoclave internal pressure 2.8k9/CItG
5. While holding the It was introduced over the course of gI1. Thereafter, aging was performed at 110°C for 2 hours. Then 1, 2-
720 g of butylene oxide was introduced into the autoclave over a period of about 2 hours, and the autoclave was further aged for 2 hours. Further, 800 g of ethylene oxide was charged over a period of 2 hours, and the three-powder reaction was continued. The product obtained by purification has an OH value of 28.5 KOHm9/g, a viscosity of 750 Cp/25°C, and contains about 1% by mass of 1,2-butylene oxide.

Reference Example 4 In the same manner as in Reference Example 3, 23.5 g of caustic potash was mixed as a catalyst with 450 g of a polyol having a molecular weight of 500, which was obtained by adding propylene oxide to propylene glycol, and the mixture was heated to 110°C.

After removing water under reduced pressure, 2450 g of 1,2-butylene oxide was added to 4. It was introduced into an autoclave over a period of time. After aging at 110℃ for 2 hours, 720℃
g of ethylene oxide was introduced into the autoclave over a period of 2 hours, and the reaction was continued for three times.

The 0H value of the product obtained through purification is 28.3K0H.
m9/g1 viscosity "770Cp/25℃, 1,2-
Contains about 68% by weight of butylene oxide. Comparative example 2 of reference example (polyol not using butylene oxide) Reference example -
In the same manner as in 3, 2850g of propylene oxide was added to 6.2
It was introduced at 1100C for a period of time.

Thereafter, it was aged for 2 hours at 11Q'C. followed by 8
00 g of ethylene oxide was introduced into the autoclave over a period of 2 hours and the reaction continued for three times. The 0H value of the product obtained through purification is 128.1K0Hm9/g1
The viscosity was 760 Cp/25°C.

Reference Example 5 Almost the same as Reference Example-3, only 1 and 2
- Polyols were prepared using 2,3-butylene oxide instead of butylene oxide.

0H of the product is 28.8K0Hm9/g1 viscosity 73■P
/25℃, about 1% 2,3-butylene oxide
including. Examples 1 to 4, Comparative Examples 1 to 2 Using the polyols produced in Reference Examples 1 and 2 according to the present invention and Comparative Example 1 of the reference example, the injection pressure was 60k9/A.
The physical properties of polyurethane elastomers molded in a high-pressure foaming machine using a flat mold were compared.

The results are shown in Table-1. Examples 5 to 9, Comparative Examples 3 to 4 Comparison of Reference Examples 3, 4, 5 and Reference Examples according to the present invention Using the polyol obtained in Comparative Example-2, a polyurethane elastomer was molded by the RIMO2 molding method. and compared the physical properties.

Claims (1)

[Scope of Claims] 1. At least two pressurized liquid streams, a pressurized liquid stream based on a polyisocyanate compound and a pressurized fluid stream based on a polyol compound. In the method of molding a polyurethane elastomer or microcellular polyurethane elastomer by mixing and injecting into a mold, at least one of the polyol compounds is added to a polyhydroxy compound with butylene oxide and an alkylene oxide other than butylene oxide (however, at least a portion of the polyol compound is ethylene oxide), and has an oxybutylene group content of 20 to 70% by weight, a terminal oxyethylene group content of 10 to 25% by weight, and a hydroxyl value of 20 to 45 KOHmg/g. A reaction injection molding method for polyurethane. 2. The method of claim 1, wherein the polyoxyalkylene polyol contains an oxypropylene group. 3 The number of hydroxyl groups in the polyoxyalkylene polyol is 2 or more
4 of claim 1, characterized in that: