JPS5937289B2 - Polyol mixture for polyurethane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyol mixture for polyurethane, which provides molded articles with high rigidity and toughness, and has good moldability.

Recently, from the standpoint of weight reduction, efforts have been made to use resin for car body parts, but when using resin, molded products are required to have the same rigidity as conventional sheet metal products, and also have elongation that can absorb shock, that is, toughness. is also required.

In the case of polyurethane molded products, in order to obtain high rigidity, a polyfunctional crosslinking agent such as an ethylene oxide adduct of sucrose is mixed with a high molecular weight polyol, and the mixture is reacted with an aromatic polyisocyanate. I was getting goods. The polyurethane molded product obtained in this way has a large number of crosslinking points and therefore has high rigidity, but its toughness (elongation rate) is significantly reduced. In view of the above, this invention
It is an object of the present invention to provide a polyol mixture for polyurethane which can obtain a molded article whose toughness does not decrease compared to an increase in rigidity and which has good moldability.

The gist of the present invention is a polyol mixture for polyurethane in which ethylene glycol and an ethylene oxide adduct of aniline are added as a crosslinking agent to a high molecular weight polyol, and a molded article can be obtained in which the toughness does not decrease compared to the increase in rigidity.

The mixture of the present invention will be explained in detail below.

Note that "parts" indicating the blending ratio is an abbreviation for "parts by weight."

The polyol mixture for polyurethane of this invention is as follows (a
) Components b) and (c) as crosslinking agents are blended in respective amounts into a polyol.

(a) Polyol having OH groups at least on both ends (molecular weight: 2,000 to 8,000): 100 parts by weight The polyol may be a polyether polyol or a polyester polyol.

Polyether polyols are obtained, for example, by reacting cyclic ethers such as ethylene oxide, propylene oxide, butylene oxide, and styrene oxide with low-molecular-weight polyols such as ethylene glycol, diethylene glycol, glycerin, and trimethylolpropane. Further, it may be a polymer polyol obtained by graft polymerizing a vinyl monomer or the like onto these. Polyester polyols are produced by reacting dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, and pimelic acid with an excess of diol components such as ethylene glycol, polyoxyethylene glycol, propylene glycol, dipropylene glycol, and polyoxypropylene glycol. Let me get it.

If the molecular weight of the polyol is less than 2,000, the molded product will not have the desired toughness, and if it exceeds 8,000, the viscosity will be high, the stability will be poor, and it will be difficult to handle. (b) Ethylene glycol...2 to 40 parts (preferably 4 to 30 parts) If the amount is less than 2 parts, the molded product will not have the desired rigidity,
If it exceeds 40 parts, moldability, ie, green strength, decreases.

(c) Ethylene oxide adduct of aniline (number of moles added; 1 to 4)...2 to 40 parts represented by the following general formula.

(However, in the formula, M.n is an integer, m+n-1 to 4) In the above, if the number of moles added is O, that is, aniline, the reaction rate becomes too fast, making molding difficult; When it exceeds 4, the effect of the benzene nucleus on increasing the rigidity of the molded product is almost eliminated.

Furthermore, if the amount is less than 2 parts, the molded product will not have the desired rigidity, and if it exceeds 40 parts, the heat resistance of the molded product will be reduced.

This ethylene oxide adduct of aniline (hereinafter abbreviated as "EO adduct") is liquid and therefore easy to handle.

Furthermore, the benzene nucleus of aniline acts to increase the rigidity of the molded product, and since it is bifunctional, it does not have much of an adverse effect on toughness. The above-mentioned polyol mixture is reacted with aromatic polyisocyanate (alphae) as described below in the presence of a catalyst (d) to obtain a molded article by reaction injection molding, cast molding, solvent molding, or the like.

(d) Catalysts Examples include amine-based catalysts such as triethylenediamine, N-methylmorpholine, pentaethyldiethylenetriamine, dimethylethanolamine, and diethylethanolamine, and tin-based catalysts such as dibutyltin dilaurate, dibutyltin fumarate, and dibutyltin acetate. .

(e) Aromatic polyisocyanate tolylene diisocyanate, phenylene diisocyanate, diphenylmethane-4,4'-diisocyanate (
(hereinafter abbreviated as "MDI"), naphthalene-1,5-diisocyanate, etc. are used.

In addition, the solvent used in the above solvent molding is N
Examples include N-N'-dimethylformamide, tetrahydrofuran, and methyl ethyl ketone, which are inert to CO groups. If you want to further improve the rigidity, add glass fiber, calcium carbonate, talc,
A filler such as mica or silica is added as appropriate (1 to 150 parts).

Furthermore, if desired, additives such as plasticizers, dyes, pigments, anti-aging agents, ultraviolet absorbers, blowing agents, etc. are added to the mixture. Hereinafter, in order to confirm the effects of this invention, Examples,
A comparative example will be given and the results of each physical property test will be shown.

Molding method A polyol mixture for polyurethane having the formulation shown in Table 1 (Example) and Table 2 (Comparative Example) was mixed with 0.02 part of dibutyltin dilaurate added as a catalyst, and degassed under reduced pressure for 1 hour. 11z71tHg), then liquid MDI (NCO2
9%) was added in an amount equivalent to NCO index 105, and mixed again for 30 seconds under reduced pressure (1 ml/LHg).

In addition, in Example 14, MD was used instead of liquid MDI.
I prepolymer (NCO26%) was used. Immediately after the above mixing was completed, the mixture was poured into the cavity of a 300 x 150 x 25 mold (maintained at 40 to 50°C), and after being left for 20 minutes, the molded product was released from the mold.

This molded product was further post-cured in a constant temperature bath at 120°C (4
h) was carried out. [Test method (1) Flexural modulus (rigidity) The above molded product was cut into 25 x 100 (square) and JISK7
Measured by 2O3.

The measuring device used was Tensilon/UTM-1/5000W (manufactured by Toyo Seiki Co., Ltd.). (2) Tensile elongation at break (
Toughness) A JIS No. 2 tampel type test piece was punched out from the molded product and measured using JIS K63Ol.

The measuring device used was Tensilon/UTM-1/5000W (manufactured by Toyo Seiki Co., Ltd.), and the tensile speed was 200 mm/
It was set as Wt.

(3) Green Strength (Moldability) The appearance of the molded product upon release from the mold was visually evaluated in the following three stages.

○...No abnormalities, △...There are some cracks, but the molded product cannot be removed.

The results of each test are shown in Tables 3 to 6.

Table 3 shows that the molded articles using the polyol mixture of the present invention showed almost no decrease in toughness compared to the increase in rigidity.

Table 4 shows that good moldability is maintained even if the amounts of ethylene glycol and aniline EO adducts are increased.

As in Comparative Examples 5 and 6, when trying to increase the rigidity using ethylene glycol alone, moldability deteriorates. Table 3 shows that the same results as in Table 2 can be obtained even when polyether polyol is used as the polyol.

It is also found that using a prepolymer as the isocyanate (Example 14) is also effective. Table 4 shows that the addition of inorganic fillers to the polyol mixtures of this invention significantly increases the stiffness.

Claims (1)

[Claims] 1. A polyol mixture for polyurethane comprising the following formulation. (a) Polyol having OH groups at least on both ends (molecular weight: 2000-8000)...100 parts by weight (b)
Ethylene glycol...2 to 40 parts by weight (c) Ethylene oxide adduct of aniline (number of moles added; 1 to 4)
...2 to 40 parts by weight.