JPS63154718A - Production of polyurethane foam - Google Patents

Abstract

PURPOSE:To improve the hardness, expansion ratio, cell uniformity, etc. of a foam without using any filler, by previously dissolving air in a polyol as a principal material in the production of a polyurethane foam by a one-shot process. CONSTITUTION:While a polyol as a principal material is fed to a tank 1 through a pipe 20, air is introduced to it through an air supply pipe 23 and is dissolved in the polyol in an air mixer 22. The polyol in the tank 1 and an isocyanate (e.g., tolylene diisocyanate), an amine catalyst (e.g., triethylenediamine), a tin catalyst (e.g., dibutyltin dilaurate), a silicone oil, a blowing agent (e.g., water) and, optionally, a pigment, a filler, etc. in tanks 2,3,4,5, etc. are fed to a mixing head 16. These components are foamed by mixing to obtain a polyurethane foam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyurethane foam, and in particular to improvements in the one-shot method.

[Conventional technology]

Urethane foam, which is widely used as various cushioning materials, bedding materials, and industrial materials, is manufactured using a continuous production method or a mold foaming method, but in either foaming method, the one-shot method requires the following basic steps. A foaming operation is adopted.

In the production of urethane foam by the one-shot method, the following components are mixed in a predetermined ratio and reacted to cause a urethane bond growth reaction, a foaming reaction, and a crosslinking reaction to occur simultaneously.

(1) Polyols such as polyether polyol and polyester polyol (2) Organic incyanates such as tolylene diisocyanate-1 and diphenolmethane diisocyanate (3) Water (blowing agent, crosslinking agent) (4) Amine (5) Fl-based catalyst (catalyst for foaming reaction) (6) Silicone oil (foam stabilizer) (7) Optional components such as pigments and fillers What are the above polyols and organic isocyanates? A urethane bond growth reaction shown by the following formula is performed.

0H-R-OH+0CN-R'-NCOHO R-NGO-R'-NGO NCO-R'-NGO I I+ O On the other hand, the foaming reaction is carried out using an organic isocyanate and water according to the following formula.

The amine produced by the foaming reaction of R-NCO+H2O-R-NH2+CO2 reacts with an organic isocyanate as shown in the following formula to form a urea bond.

R-NH, L+R-NCO Further, the crosslinking reaction is carried out by the reaction between the above urea bond and the terminal NCO group of the urethane growing chain formed by the above growth reaction as follows.

The properties of polyurethane foams produced by such complex reactions, such as density and hardness, vary depending on the balance of the various reactions described above, so polyurethane foams with various properties can be produced by controlling the balance of these reactions.

However, it is generally difficult to control the reaction balance, and the range of physical properties that can be changed is limited to a certain narrow range. For this reason, for example, in order to improve the hardness of polyurethane foam, a conventional method has been to add a filler such as starch to the raw material and foam it.

[Problem that the invention seeks to solve]

However, the conventional method of changing the hardness, etc. of polyurethane foam products using fillers naturally has the problem of increasing raw material costs.

Further, since the use of fillers generally tends to inhibit the foaming reaction, there is a problem of lowering the foaming ratio and causing non-uniform foaming.

The present invention has been made in view of the above circumstances.

The object of the present invention is to provide a method for producing polyurethane foam that can increase the hardness of the polyurethane foam without using fillers, improve the expansion ratio, and make the cells uniform.

[Means for solving problems]

The method for producing urethane foam according to the present invention involves mixing and stirring polyols, organic isocyanates, amine catalysts, tin catalysts, silicone oil 1 blowing agent, pigments, fillers, etc. as necessary, and foaming them in advance. It is characterized in that air is dissolved in the polyol.

In the present invention, the following method can be used to previously dissolve air in the polyols that are the raw material components.

The first method is to mix air when introducing the polyol raw material into the storage tank, dissolve it under pressure in the tank, and store it (Figure 1).

The second method is a method in which air is mixed and dissolved when polyols are taken out from a raw material tank to be mixed with other raw materials (Figure $3).

[Effect]

In the present invention, since a large amount of oxygen is dissolved in the polyol compared to the conventional method, this dissolved oxygen increases the hardness of the polyurethane foam, improves the expansion ratio, and makes the cells uniform.

Although its detailed effect is not yet clear, it can be considered as follows.

First, the effect of increasing hardness is thought to be due to the biradical nature of dissolved oxygen, which is thought to promote the crosslinking reaction.

Secondly, the improvement in the foaming ratio is thought to be due to the fact that dissolved oxygen separates from the polyol during mixing and stirring of the raw materials, which adds a foaming effect.

Thirdly, it is thought that the uniformity of foaming is also due to the addition of the stirring effect of vaporized dissolved oxygen.

〔Example〕

First, an example of an apparatus for implementing the present invention will be described.

FIG. 1 is an explanatory diagram showing an example of an apparatus used for carrying out the present invention. In the figure, 1 is a polyol tank, 2 is an isocyanate tank, 3 is an amine catalyst tank, 4 is a tin catalyst tank, and 5 is a blowing agent (water) tank. Corresponding raw materials are stored in these raw material tanks 1 to 5, respectively. In addition, the lower end of each raw material tank has valves 6 to 10, respectively.
and is connected to a mixing head 16 via piping 11-15. In addition, pumps 17 and 18 for pumping raw materials are arranged in the pipes 11 and 12. A stirring blade rotated by a motor 19 is provided inside the mixing head 16, and the raw materials sent from each raw material tank are stirred and mixed there and discharged from the nozzle.

Incidentally, a pipe 20 for supplying polyol into the tank is provided at the upper end of the polyol tank 1. The pipe 20 is provided with an air mixer 22 for mixing and dissolving air introduced from an air feed pipe 23 in addition to the pulp 21 into the polyol.

FIG. 2 is an enlarged view of the air mixer 22. As shown in FIG. The amount of air introduced from the air supply pipe 23 is determined by the flowmeter 2.
It is measured at 5. The aerated polyol is mixed by a worm screw 26 while passing through the mixer 22, and the air is uniformly dissolved. Note that 27 is a motor for rotating the worm screw 26.

The polyol containing air is stored in the polyol tank 1, but the inside of the polyol tank 1 is kept under pressure so that the dissolved oxygen does not separate. This pressure may be about 2 to 7 kg/c113.

Note that it is not necessary to dissolve air in the polyol before storing it in the polyol tank 1 as described above.

The point is that air should be dissolved in the polyol before it is mixed in the mixing head 16. Therefore, for example, the present invention can also be implemented using the device a shown in FIG.

In the apparatus shown in FIG. 3, an air mixer 22 having the same configuration as that explained in FIG. It is supposed to be done.

Examples performed using the above apparatus will be described below.

Examples Polyether polyol Triethylene diamine 1.0 Dibutyltin dilaurate 0.11 Silicone oil 1.5H204
, 2 Trichloromonofluoromethane 4,0 Tolylene diisocyanate 54.0 Apply 4 kg of pressure to the tank containing the polyether polyol, supply air from the air supply pipe, circulate the polyether polyol for 30 minutes, and then It was foamed by the shot method.

The density of the obtained flexible polyurethane foam is 0.01k
g/am', the hardness was 9.1 kg/JIS Te, and the bubbles were uniform.

Polyurethane foam produced using the same recipe without supplying air had a density of 0.0186 kg/0 m3 and a hardness of 8.4 kg/JIS.

〔Effect of the invention〕

As detailed above, according to the present invention, remarkable effects such as increasing the hardness of polyurethane foam without using fillers, improving expansion ratio, and making cells uniform can be obtained. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the device used for carrying out the present invention, FIG. 2 is an enlarged view of a part thereof, and FIG. 3 is another example of the device for carrying out the present invention. FIG. l...Polyol tank, 2...Isocyanate tank, 3...Amine catalyst tank, 4...Tin catalyst tank, 5...Blowing agent (water) tank, 6-10...
Valve, 11-15...Piping, 16...Mixing head 17.18...Pump, 19...Motor, 2
0... Piping, 21... Valve, 22... Air mixer, 23... Air feed pipe 23. 25... Flow meter 25
．． 26...Screw, 27...Motor applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] When mixing and stirring polyols, organic isocyanates, amine catalysts, tin catalysts, silicone oil, blowing agents, pigments, fillers, etc. as necessary, and foaming, air is dissolved in the polyols in advance. A method for producing polyurethane foam, characterized in that: