JPS5823406B2 - Nanshitsu Urethane Foam No Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the method of manufacturing closed-cell flexible polyurethane foam.

Generally, flexible polyurethane foam has an open cell structure.

It is made up of structures.

Therefore, such flexible polyurethane foam has insulation properties,
It has poor sound insulation properties and is difficult to be used as an interior material for making a room heat-insulating or sound-proof.

From this point of view, conventional methods have been attempted to obtain flexible polyurethane foams consisting of closed cells.

That is, flexible polyurethane foam is produced by adding and reacting a catalyst, a blowing agent, and an organic incyanate to a flexible polyol. In this case, among the tin-based catalyst and amine-based catalyst used as a catalyst, particularly effective foaming is performed. Careful attention is paid to the amount of tin-based catalyst added, and it is extremely important to adjust the amount.

Therefore, the amount of tin-based catalyst added is 100% of the normal soft polyol.
The catalyst is used in an amount of about 0.05 to 0.5 parts by weight, but as mentioned above, the catalyst has a delicate effect,
Adjustment is extremely difficult, and depending on the amount added, the flexible polyurethane foam will shrink significantly, resulting in irregular shapes.

Therefore, it was not possible to always obtain a constant molded product.

In the case of using the above method, the reaction heat is relatively high (usually 150 to 170°C), so if left in this state, it is easy to cause scorch (scorch) inside the foam, making it difficult to use high-quality flexible polyurethane foam. It was difficult to obtain.

The present invention has been made as a result of extensive research aimed at improving these drawbacks, and has resulted in the discovery of a method for easily and stably producing flexible polyurethane foam consisting of closed cells.

That is, in the present invention, a polyhydroxy compound having three or more functional groups and an OH value of 70 or more is mixed with an organic incyanate, and the mixture is reacted with 20 to 70 parts by weight of a urethane prepolymer having an OH group at the end. It is characterized by mixing 80 to 30 parts by weight of polyether polyol, further adding organic isocyanates, tin-based and amine-based catalysts, foam stabilizers, and other flame retardants and extenders as necessary, and allowing the mixture to react. That is.

In the present invention, the reason why polyhydroxy compounds are limited to 3 or more functional groups and OH value 70 or more is that when using polyhydroxy compounds with 2 or less functional groups and OH value less than 70, they are often open-celled. This is to obtain a form with less .

Therefore, the OH value is preferably in the range of 70 to 250.

Examples of polyhydroxy compounds having three or more functional groups and an OK value of 70 or more include glycerin, trimethylolpropane (trifunctional), pentaerythritol, α
- Methyl glycoside (tetrafunctional), ethylenediamine, nrubitol, sucrose, etc. are added and polymerized with ethylene oxide, propylene oxide, etc. to have an OH value of 70 or more.

In addition, the urethane prepolymer is a polyhydroxy compound (O
H value 70 to 250) and organic isocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate are obtained by a conventional method.

In this case, it is necessary to adjust the amount of incyanate so that the OH group of the polyhydroxy compound reacts with the NCO of the isocyanate, resulting in an OH terminal.

In the present invention, in order to obtain a soft polyol, for example, ethylene glycol, diethylene glycol, propylene glycol, (bifunctional) glycerin (trifunctional), etc. are added and polymerized with ethylene oxide, propylene oxide, etc. to obtain a polyol having an OH value of approximately less than 70. is used.

Further, in the method of the present invention, urethane prepo IJ-f-2
The reason for blending at a ratio of 0 to 70 parts by weight and 80 to 30 parts by weight of the flexible polyol is that if the mixing reaction is carried out outside this range, it will not be possible to obtain a sufficient closed-cell flexible polyurethane foam. It is.

In the method of the present invention, the foam stabilizer is silicone, etc., and other flame retardants, fillers, etc. may be added as appropriate.

Next, examples of the present invention will be described.

Example 1 10 parts by weight of triene diisocyanate was added and mixed to 100 parts by weight of a polyether polyol having a functional molecular weight of about 1000.3 and an OH value of 165, and the mixture was stirred and reacted at 90°C for 3 hours to obtain a prepolymer with residual OH #100. .

A soft urethane foam was obtained using this prepolymer according to the following formulation.

The obtained foam was good and had uniform closed cells throughout.

Example 2 Using the prepolymer obtained in Example 1, a soft urethane foam was obtained according to the following formulation.

The obtained foam was good and had uniform closed cells throughout.

Comparative example 1 A soft urethane foam was obtained using the following formulation.

The obtained foam had some closed cells in the lower part, but open cells in the middle and upper part.

The results of measuring the air flow at each position in the upper, middle, and lower positions of the urethane foam molded product obtained by the method of the present invention (Example 1) and the urethane foam molded product obtained by the comparative example as shown in FIG. As shown in the figure.

As detailed above, according to the method of the present invention, by mixing a urethane prepolymer and a flexible polyol, it is possible to obtain a flexible polyurethane foam that is completely free from deformation due to shrinkage and has uniform closed cells throughout.

Furthermore, since the internal heat generation during the reaction process is extremely low, there is no risk of internal scorch, etc., and it has remarkable effects such as obtaining products of excellent quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a sample for measuring the airflow rate of urethane foam, and FIG. 2 shows the relationship between the upper, middle, and lower positions of the sample and the airflow rate.

Claims (1)

[Scope of Claims] 1 Urethane prepolymer having OH group at the end, which is obtained by mixing a hydroxyl compound having 3 or more functional groups and having an OH value of 7.0 or more with an organic isocyanate and reacting the mixture. 70 parts by weight and 80 parts by weight of soft polyol
-30 parts by weight, and further blended with an organic incyanate, a tin-based and amine-based catalyst, a foam stabilizer, a flame retardant, an extender, etc. as necessary, and then mixed and reacted. Method for manufacturing soft urethane foam.