JPS5834502B2 - Manufacturing method of hard urethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a rigid urethane foam in which the foaming pressure is extremely low during foam production.

Rigid urethane foam has recently been used in a wide range of applications such as insulation materials, building materials, and furniture materials due to its many excellent physical properties such as excellent heat insulation and excellent mechanical strength, as well as its versatility in processability.

As one of these methods, injection foaming on walls and the like is often performed as a method that takes advantage of the self-adhesive properties of urethane.

However, in the production of conventional rigid urethane foams, there has been a peculiarity in that extremely high foaming pressures are applied during foam generation.

In other words, in the method usually called the conventional method,
A liquid foaming agent was previously added to the polyol component at room temperature, and then the polyisocyanate component was mixed and foamed and cured.

This method has the drawback that the urethane stock solution expands by about 30 degrees after being discharged, resulting in an extremely high foaming pressure, and the means to deal with this high foaming pressure has been a major problem.

In the past, in order to solve these problems, the molds were made stronger, a stronger press was used, or the walls were significantly reinforced.

For this reason, a large amount of equipment was required and the workability was poor.

Furthermore, methods for lowering the foaming pressure during foam generation have also been developed and put into practical use.

In this method, a blowing agent that is a gas at room temperature is mixed into the mixing head of a foaming machine at the time when the polyol component and the polyisocyanate component are mixed. Even if a large amount of foaming agent is mixed in, there is a limit to its effectiveness, so a polyol component that has been mixed with a foaming agent that is liquid at room temperature has been used.

That is, there is a method of two-stage foaming called the floss method.

However, even in this method, since a foaming agent which is liquid at room temperature was used, there was an expansion of about 4 to 10 degrees after the urethane stock solution was discharged, resulting in a considerable foaming pressure, which was insufficient.

The present invention has been made with the aim of solving these drawbacks, and is aimed at developing a method for producing a rigid urethane foam that reduces the foaming pressure during foam generation.

In the present invention, an internal pressure of 20 kg/<- or more is applied to a pressure-resistant container and a hose containing a polyol component and a polyisocyanate component, and either one of the pressure-resistant container and hose or the pressure-resistant container and hose is The method is characterized in that a foaming agent having a boiling point of 5° C. or less is mixed in liquid form at a pressure higher than the pressure above, and then the polyol component and the polyisocyanate component are mixed and foamed and hardened.

The stock solution for urethane foam production consists of polyisocyanate fraction, polyol, reaction catalyst,
It is not a two-component system consisting of a polyol component mixed with a foam stabilizer and other additives, and is further comprised of a blowing agent that is gaseous at room temperature with a boiling point of 5° C. or less.

The present invention is characterized in that the blowing agent having a boiling point of 5°C or less is mixed in liquid form into the polyol component and the polyisocyanate component.

In other words, in order to mix a blowing agent with a boiling point of 5°C or less in liquid form, first, a pressure-resistant container and a hose containing the polyol component and polyisocyanate component are mixed with 20°C using a pump or the like.
Apply an internal pressure of kli'/ff1 or higher.

This internal pressure needs to be 20 kg/ci or more, preferably around 40 kgy.

Mixing a foaming agent in liquid form with a boiling point of 5°C or less at a pressure higher than the internal pressure into either the pressure-resistant container and hose to which the internal pressure is applied in this way, or the pressure-resistant container and hose,
Mix with polyol component and polyisocyanate component.

Here, the amount of the blowing agent with a boiling point of 5°C or less is 5 to 25% by weight relative to the polyol component and polyisocyanate component, respectively.
% is good.

Examples of the blowing agent that is a gas at room temperature and has a boiling point of 5° C. or less used in the present invention include dichlorodifluoromethane, monochlorodifluoromethane, and dichlorotetrafluoroethane.

Also, water, which is normally used as a blowing agent for urethane foam, is not used in the present invention because it reacts with polyisocyanate and generates carbon dioxide gas, resulting in high pressure.

As the polyol, polyether polyols are preferred, and include polyether polyols using sucrose, sorbitol, glycerin, trimethylolpropane, penquerythritol, hexanetriol, ethylenediamine, triethanolamine, etc. as an initiator.

As the polyisocyanate, all commonly used polyisocyanates can be used, including tolylene-2,4-diisocyanate, tolylene-26-diisocyanate, and mixtures thereof;
diphenylmethane-4,4'-diisocyanate, 3-
Although methyldiphenylmethane-4,4'-diisocyanate and crude products thereof are used, crude diphenylmethane-4,4'-diisocyanate is preferred.

As for the reaction catalyst, foam stabilizer, flame retardant and other additives, all those commonly used in the production of urethane foam can be used.

The present invention is constructed as described above, and weighs 20 kg.
By mixing a liquid blowing agent with a boiling point of 5°C or less at a pressure higher than the internal pressure into a pressure-resistant container and a hose that have an internal pressure higher than /i, or a pressure-resistant container and a hose, the blowing agent can be uniformly produced with little loss. It can be mixed into the polyol component and the polyisocyanate component without any residue, and can be mixed in a large amount.

In this way, the present invention does not require the use of a foaming agent that is liquid at room temperature as in the past, so the urethane stock solution is already discharged in the form of foam, and after discharge, the foam is approximately 1.1 to 1.5 times the amount of foam. Since the foaming reaction is completed with the expansion of , the foaming pressure becomes extremely low.

In the case of hard urethane foam used as a conventional insulation material, the expansion rate until the foaming reaction is completed is about 20 to 40 times, the degree pressure is about 0.5 to 1.0 ky/i, and when using the floss foaming method. In the present invention, the expansion rate is about 4 to 10 times and the foaming pressure is about 0.2 to 0.7 kg7, whereas in the present invention, the expansion rate is about 1.1 to 1.5 times, and the foaming pressure is about 0. 1
kvcriL becomes low.

In the present invention, the foaming pressure during foam generation is extremely low, so even when mold injection foaming, injection foaming into a panel, or injection foaming into a wall, a strong mold, a strong press machine, or a strong reinforcing means is required. without the need for
This is an extremely useful manufacturing method as it not only eliminates the need for expensive equipment but also improves workability.

Comparative examples and examples will be explained below.

Comparative Example I Liquid A Crude diphenylmethane 4,4-diisocyanate 108 parts B Glycerin-based polyol 100 (molecular weight 400) Silicone foam stabilizer (SH-1,93) 1 Blowing agent (trichloromonofluoromethane) 40 Amine catalyst ( Dimethylethaneolamine 1.2 Flame retardant (TC
EP) 10 Liquid temperature A liquid, B liquid 20°C Cream time (CT) 60 seconds Rise time (RT) 160 seconds The two components of liquid A and B in the above formulation are mixed using a foaming machine, and then discharged and foamed to generate a foam. I let it happen.

(Discharge amount: 4.5 kV) As a result, the mixed liquid was discharged in a liquid state, and when foaming was completed, the volume expansion was 35 times.

The foaming pressure in mold foaming was about 1.0 kg/i.

The density of the obtained foam was 30:9/ffl.

Comparative Example 2 When mixing the two components of liquid A and liquid B in the above formulation, the total weight was 6.
% of dichlorodifluoromethane was added at the same time, and the mixture was discharged in the form of a floss and foamed to form a foam.

(Foam density 28 kgy award) The foam discharged in the form of floss further expanded about 6 times.

The foaming pressure during mold foaming was approximately 0.5%.

Example: 40kgA- of the above-prescribed liquids A and B were sucked with a pump.
Dichlorodifluoromethane was injected in liquid form at a pump pressure of 50 ky/crit into each of the A and B liquids in the pressure-resistant hoses, which were fed at the internal pressure of the rIL, at a weight ratio of 8% to the A1B liquid.

Next, these A liquid and B liquid were mixed and discharged by a foaming machine.

(Discharge amount: 5 approximately maintained) As a result, the mixed liquid was discharged in the form of foam, and the foaming of the discharged foam was completed, and the volume expansion remained at about 1.5 times until hardening.

Foam foaming pressure is 0.05 kg/cr? It was about L.

The obtained foam density was approximately 33.

Claims (1)

[Claims] 1 Apply an internal pressure of 9 to 9 degrees or more to a pressure-resistant container and hose containing a polyol component and a polyisocyanate component, and apply the internal pressure to either the pressure-resistant container and hose or the pressure-resistant container or hose. Boiling point 5 at pressures above
A method for producing a rigid polyurethane foam, which comprises mixing a blowing agent in liquid form at a temperature of 0.degree.