JPS6320250B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an impact-absorbing urethane foam with excellent impact energy absorption rate. Polyurethane foam is used in armrests, crash pads, dash boards, etc. as interior parts of automobiles with excellent impact energy absorption properties, and in recent years, automobiles have begun to be equipped with impact-absorbing urethane bumpers made of polyurethane foam. It's here. The impact energy-absorbing polyurethane foam used in these products is made by mixing organic isocyanate in a mixture of a high molecular weight polyol and a short chain polyol in the presence of water or a blowing agent such as an inert vaporizing agent, a catalyst, a surfactant, etc. It is a semi-rigid urethane foam with a relatively low density that is foamed by reacting. However, when producing the above-mentioned semi-rigid foam, the resulting foam has a high degree of closed cells, and the foam tends to shrink or crack or crack due to abnormal heat generation during foaming, and is susceptible to impact energy. It has the disadvantage of low absorbency. The present invention relates to a method for manufacturing a polyurethane foam that eliminates the above-mentioned drawbacks in foam manufacturing and has high impact energy absorption properties. That is, in the present invention, when producing a polyurethane foam by reacting a polyol with an isocyanate in the presence of a blowing agent, a catalyst, a surfactant, etc., 10 to 30% by weight of a vinyl compound copolymer is added to a polyether type polyol as a polyol. % graft polymerized polymer polyol with an OH value of 20 to 160 and an OH value of 130 to 350, preferably 2 to 7 with an OH value of 130 to 200.
It consists of a mixture of 2,2'(4-hydroxyphenyl)propane containing an equivalent amount of oxypropylene, and the weight ratio of the above polymer polyol and 2,2'(4-hydroxyphenyl)propane containing 2 to 7 equivalents of oxypropylene is The present invention provides a method for producing impact energy absorbing urethane foam, characterized in that a polyol mixture having a polyol content of 0.3 to 2.5 is used. The polyol used in the present invention is obtained by graft polymerizing 10 to 30% by weight of a vinyl compound such as styrene and/or acrylonitrile to a polyether type polyol, and has a functional group number of 2 to 6 and an OH value of 20 to 160.
Polymer polyol with 2 functional groups and OH value 130
~350, preferably from 130 to 200, in a mixture with 2,2'bis(4hydroxyphenyl)propane containing 2 to 7 equivalents of oxypropylene, but the OH number of said polymer polyol is less than 20. The strength decreases, and if it exceeds 160, the recovery rate of the foam decreases, causing a change in appearance after compression. 2 containing 2 to 7 equivalents of oxypropylene,
2'bis(4hydroxyphenyl)propane is OH
When the value is 300 or more, the viscosity becomes high, and when mixed with organic polyisocyanate, catalyst, blowing agent, etc., it is difficult to form a uniform product, a non-uniform reaction occurs, and the resulting foam has poor physical properties. Furthermore, when oxyethylene is used in place of oxypropylene, the resulting diol has high crystallinity and poor compatibility with polymer polyols, making it difficult to handle. The mixing ratio of the above polyol is 2 to 7 to the polymer polyol.
The weight ratio of 2,2'bis(4hydroxyphenyl)propane containing an equivalent amount of oxypropylene, from 0.3 to
Must be within the range of 2.5. When the weight ratio is less than 0.3, the recovery rate of the obtained foam decreases, and when it exceeds 2.5, the compressive strength of the obtained foam decreases. The organic polyisocyanates used in the production of the semi-rigid polyurethane foam products of the present invention may be those known and used in the production of conventional polyurethane foams, such as tolylene diisocyanate, crude diphenylmethane diisocyanate, hexamethylene diisocyanate, m and p-xylene diisocyanate, polymethylene polyphenyl polyisocyanate, and mixtures thereof, or prepolymers having unterminated isocyanate groups obtained by reacting these organic isocyanates with polyols can also be used. The above examples are not intended to limit this. . The amount of isocyanate used may be that applied to conventional polyurethane foams, ie, an amount corresponding to an isocyanate index of 100 to 115. Examples of the blowing agent used in the present invention include water and inert vaporizing agents such as trichloromonofluoromethane and dichlorodifluoromethane. The amount added for each composition above is the total amount of polyol.
Per 100 parts by weight, 1 to 4 parts by weight of water and 0 to 10 parts by weight of inert vaporizing agent. In addition to the components described above, silicone surfactants, amine catalysts such as ethylenediamine, trimethylamine, and ethylmorpholine, and tin catalysts such as dibutyltin dilaurate can be used. The amounts of each of the above components added are 0 to 3 parts by weight of the silicone surfactant and 0 to 3 parts by weight of the catalyst. The above composition is foamed in a closed mold. The above blowing agents and catalysts are not limited to these examples. Thus, an excellent polyurethane foam with high impact energy absorption capacity is obtained. Next, an example,
A comparative example will be explained in detail. Examples 1 to 3, Comparative Examples 1 to 2 As a polymer polyol, a polyol with an OH value of 25 obtained by graft polymerizing a copolymer of 10% each of styrene acrylonitrile to a polyether type polyol.
(A) and the oxypropylene derivative (B) of 2,2'bis(4hydroxyphenyl)propane with an OH value of 196.
It was used at a ratio of 1:1. Table 1 shows the physical properties of the obtained foam.

【table】

[Table] Examples 1 to 3 not only have high impact energy absorption ability but also excellent recovery rate. In Comparative Example-1, the recovery rate was good, but the impact energy absorption ability was low. Comparative Example 2 has good impact energy absorption ability but poor recovery rate. Note that the energy absorption efficiency referred to here is a measure of the energy absorption ability of the foam, and the compression load-strain curve f was determined by a static compression load test of the sample.
(γ), which shows the ratio of energy absorbed by the foam to the energy applied to the sample at 50% compression, ∫ ^0.5 ₀ f(γ)dγ/0.5×f(0.5)×100 (%).

Claims (1)

[Claims] 1. In producing polyurethane foam by reacting polyol with isocyanate in the presence of a blowing agent, catalyst, surfactant, etc., 10 to 30% by weight of a vinyl compound copolymer is graft-polymerized to polyether type polyol as the polyol. OH value
Polymer polyol from 20 to 160 and OH number from 130 to 350
containing 2 to 7 equivalents of oxypropylene, 2,
consisting of a mixture of 2'bis(4hydroxyphenyl)propane, containing the above polymer polyol and 2 to 7 equivalents of oxypropylene, the weight ratio of 2,2'bis(4hydroxyphenyl)propane being 0.3 to 2.5;
A method for producing an impact energy-absorbing urethane foam, characterized in that it uses a polyol mixture.