JPH0687972A - Expanded heat insulating material and heat insulating box body - Google Patents

Abstract

PURPOSE:To obtain an expanded heat insulating material, capable of applying a low-pollution hydrochlorofluorocarbon as a foaming agent and having uniform fine cells without any froth voids, etc., by using a specific polyol component and a very small amount of a perfluoroalkane. CONSTITUTION:The material is obtained by mixing and stirring (A) an organic polyisocyanate with (B) a polyol component containing at least 5-25% hydroxyl group component of the formula (n is >=2) (e.g. diethylene glycol), (C) a foam stabilizer (e.g. a silicone-based surfactant), (D) a catalyst, (E) a foaming agent containing a hydrochlorofluorocarbon having -50 to 0 deg.C boiling point, (e.g. chlorodifluoromethane) as a component and (F) a 4-7C perfluoroalkane (e.g. perfluoropentane) in an amount of 0.1-5 pts.wt. based on 100 pts.wt. component (B).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed heat insulating material and a heat insulating box used for refrigerators, freezers and the like.

[0002]

2. Description of the Related Art In recent years, chlorofluorocarbons (hereinafter C
Environmental problems such as ozone depletion and global warming due to the influence of (FC) are attracting attention, and in manufacturing a hard urethane foam, which is a typical foam insulation material, C
For the purpose of reducing the amount of FC used, a method of using carbon dioxide gas obtained by the reaction of organic polyisocyanate and water as a part of a foaming agent, or an alternative substance of CFC, which has little effect on ozone destruction2, Various improvements such as foaming with 2-dichloro-1,1,1-trifluoroethane and 1,1-dichloro-1-fluoroethane are being studied.

Conventionally, in the production of foams, foaming with trichlorofluoroethane (hereinafter referred to as CFC11) having a boiling point near room temperature or a floss method using dichlorodifluoromethane (hereinafter referred to as CFC12) which is a low boiling point foaming agent, etc. Has been used.

By using a low boiling point compound such as CFC12 as a part of the foaming agent, the foaming raw material liquid is discharged in a cream shape from the nozzle of the foaming machine. Therefore, although the flow of the raw material liquid is small, the bubble shape is close to a spherical shape, and the internal pressure of the gas trapped in the bubbles is high, so that a foam having excellent low-temperature dimensional stability can be obtained.

For example, Japanese Patent Laid-Open No. 59-38240 discloses low-boiling blowing agents such as 1-chloro-2,2,2-trifluoroethane, monobrom monochlorodifluoromethane,
2 to 1 of at least one compound of trans-1-chloro-2-fluoroethylene based on 100 parts by weight of total polyol.
It is characterized by using a mixture of 50% by weight to produce a foamed heat insulating material.

[0006]

However, as mentioned in Japanese Patent Application Laid-Open No. 59-38240, in the floss foaming by using the low boiling point foaming agent alone or in a large amount, the inside of the foam is A large number of froth voids are likely to occur, the cells become non-uniform, the closed cell ratio deteriorates, and the thermal conductivity of the foam deteriorates.

As a cause of these froth voids and cell communication, there is a limit to the compatibility between the low boiling point foaming agent and the polyetherpolyol generally used as a raw material for a rigid urethane foam, and it exceeds a certain level. In such a case, it is considered that the low boiling point foaming agent dissolved in the raw material cannot be retained, and a bumping phenomenon occurs at the moment of discharge, resulting in poor mixing and coalescence of bubbles.

For this reason, as a means for preventing froth voids and communication of bubbles, as shown in JP-A-59-38240, CFC1 which is a foaming agent having a boiling point near room temperature is used.
There is a method of auxiliary foaming by using carbon dioxide gas generated by mixing with 1 or reaction of water and isocyanate, but from the viewpoint of solving global environmental problems and saving energy,
Low boiling point hydrochlorofluorocarbons (hereinafter referred to as HCFC) and hydrofluorocarbons (hereinafter referred to as HFC), which have little effect on ozone layer depletion and global warming, are added to conventional high pressure agents. The problem was to manufacture a high-performance foam insulation material that can be applied without major changes to the foaming machine equipment and that does not have the problem of froth voids.

In view of the above-mentioned problems, the present invention is an excellent foam insulation material that does not have the problem of froth voids or cell communication even when a foaming agent such as HCFC or HFC having a low boiling point that has little influence on global environmental problems is used. It is intended to provide.

[0010]

In order to solve the above problems, the present invention provides an organic polyisocyanate and a polyol component containing at least 5 to 25% of a component having a molecular structure of (Chemical formula 1). , Foam stabilizer, catalyst, and boiling point -50 ° C
A foaming agent containing at least one component of HCFC at 0 ° C or lower and 0.1 to 5 parts by weight of perfluoroalkane having 4 to 7 carbon atoms per 100 parts by weight of polyol is mixed and stirred, This is to obtain a foam insulation material.

Furthermore, the present invention comprises at least 5 to 5 parts of the organic polyisocyanate and the component having the molecular structure of (Chemical formula 1).
A polyol component containing 30%, a foam stabilizer, a catalyst,
A blowing agent containing at least one component of HFC having a boiling point of -50 ° C or higher and 0 ° C or lower, and 0.1 to 5 parts by weight of perfluoroalkane having 4 to 7 carbon atoms per 100 parts by weight of polyol. Is mixed and stirred to obtain a foamed heat insulating material.

Further, the foamed heat insulating material is foamed and filled in a space portion constituted by an inner box and an outer box to obtain a heat insulating box body.

[0013]

With the above structure, the compatibility between the hydroxyl component having the molecular structure of (Chemical formula 1) and the low boiling point blowing agent composed of HCFC or HFC is extremely good, and therefore the solubility with the low boiling point blowing agent is extremely poor. By blending a hydroxyl group component having a molecular structure of (Chemical Formula 1) with a general hard urethane foam polyetherpolyol, a low boiling point blowing agent composed of HCFC or HFC as a whole polyol component is obtained. And the solubility of
The perfluoroalkane of 0.1 to 5 parts by weight with respect to 00 parts by weight and having 4 to 7 carbon atoms forms the central core of the fine bubbles, and uniform foaming behavior is obtained, thereby forming uniform fine bubbles. It is something that can be made possible.

Furthermore, HFC has an ozone depletion coefficient of 0, and not only does it have no effect on ozone depletion alone, but it also causes ozone depletion in a mixed system with HCFC, which has some effect on ozone depletion. On the other hand, it is possible to produce an effective foam insulation material.

Further, by filling the foamed heat insulating material to form the heat insulating box, there is no problem such as sweating at the void occurrence portion and deterioration of heat insulating performance, and the quality as an excellent heat insulating box can be secured. It is a thing.

As the HCFC foaming agent, chlorodifluoromethane (hereinafter referred to as HCFC22), 2-chloro-1,1,1,2-tetrafluoroethane, 1-chloro-1,1-difluoroethane, etc. are used. it can. Further, as an HFC foaming agent, 1,1,1,2-pentafluoroethane (hereinafter referred to as HF
C134a), 1,1,1,2,2, -pentafluoroethane, 1,1-difluoroethane, etc. can be used, but HF
Since the amount of dissolved C is worse than that of HCFC, when HFC is used, a mixed system with HCFC is suitable for improving physical properties such as heat insulation.

[0017]

EXAMPLES Hereinafter, the foamed heat insulating material of the present invention will be described with reference to examples.

Polyol A is an aromatic amine-based polyester.
Hydroxyl value is 460 mg KOH / g with terpolyol, and hydroxyl value is 1,056 m as a hydroxyl group component having a molecular structure of (Chemical formula 1)
gKOH / g diethylene glycol, catalyst is Kaoizer No. 1 manufactured by Kao Corporation, foam stabilizer is silicone surfactant F-335 manufactured by Shin-Etsu Chemical Co., Ltd., blowing agent is water, HCFC22
Each of the HFC134a, HFC134a, and perfluoropentane raw materials are mixed in a predetermined mixing ratio to form a premix component. On the other hand, the isocyanate component is an organic polyisocyanate composed of a crude MDI having an amine equivalent of 135.

The premix component thus prepared and the isocyanate component are mixed in a predetermined mixing number, foamed by a high-pressure foaming machine, and filled inside a box consisting of an inner box and an outer box,
An insulated box was obtained. In order to evaluate the solubility of the foaming agent at this time, the pressure of the tank filled with the premix, the presence or absence of froth voids, the closed cell rate, the thermal conductivity, and the average cell diameter are shown in (Table 1).

At the same time, as a comparative example, when the hydroxyl component having the molecular structure of (Chemical formula 1) is not added (Comparative example A)
Table 1 shows the cases where and 35% by weight of diethylene glycol based on the total amount of the polyol component (Comparative Example B) and the case where perfluoropentane was not added (Comparative Example C).

[0021]

[Table 1]

As described above, the foamed heat insulating material of the present invention is HCFC which is a low-boiling-point foaming agent with few problems against ozone destruction.
No. 22 and HFC134a are used, a raw material system that can be stably dissolved in a premix and can be easily foamed by a conventional high-pressure foaming machine, and a minute amount of added perfluoroalkane is fine bubbles It was found that a fine and uniform cell structure was obtained by forming a central nucleus of the, and a uniform foaming behavior, and an excellent foam insulation material having a high closed cell rate was obtained.

Although the details of this mechanism are unknown, it is excellent because the ether bond in the molecular structure of the hydroxyl group component having the molecular structure of (Chemical formula 1) has a strong affinity for HCFC or HFC. It is considered that the compound exhibits solubility, and the solubility of the entire polyol component is improved by using it as a part of the polyol component.

As a result, the HCFC dissolved in the polyol
Alternatively, HFCs can be uniformly foamed, and a foamed heat insulating material having excellent physical properties in terms of heat insulating properties can be obtained without causing froth voids or bubble breaking phenomenon caused by bumping of a low boiling point blowing agent. In addition, the perfluoroalkane added in a trace amount was
It is thought that since it has poor solubility with the component, it quickly becomes the core of foaming and helps the main foaming agent to foam.

As described above, the foamed heat insulating material of the present invention contributes to solving environmental problems such as ozone layer depletion by using HCFC or HFC having a low boiling point and a low boiling point as a foaming agent. By using the hydroxyl group component with the molecular structure of) as a part of the polyol component, the raw material solubility can be improved, and various highly adiabatic raw materials that could not be applied due to the extremely poor solubility of the foaming agent can be selected. It is possible to contribute to quality improvement by energy saving due to excellent heat insulation performance.

Furthermore, an HFC having an ozone depletion potential of 0
By using, it is possible to produce an effective foam insulation material against global environmental problems.

The heat-insulating box body filled with the foamed heat-insulating material can secure excellent quality as a heat-insulating box body without problems such as perspiration at the void generation portion and deterioration of heat insulation performance.

In the comparative example, when the hydroxyl group component having the molecular structure of (Chemical Formula 1) was not added (Comparative Example A), the low boiling point foaming agent could not be sufficiently dissolved, and the mixed polyol component was not able to be dissolved. The pressure increased, and bumping occurred at the time of discharge, resulting in non-uniform mixing, and it was not possible to form a foam due to the generation of froth voids, bubble breakage, and the like.

Further, when 35% of the hydroxyl group component having the molecular structure of (Chemical formula 1) is added to the entire polyol component (Comparative Example B), the low boiling point blowing agent can be sufficiently dissolved. However, due to the compositional characteristics of the polyol component, the closed cell ratio was lowered, and the heat insulating performance was significantly deteriorated.

In addition, when perfluoropentane was not added (Comparative Example C), the average bubble diameter of the obtained heat insulating material was large, and sufficient heat insulating performance could not be improved.

[0031]

As described above, according to the present invention, an organic polyisocyanate, a polyol component containing a hydroxyl component having a molecular structure of (Chemical formula 1), a foam stabilizer, a catalyst, and a boiling point of Mixing a blowing agent containing HCFC or HFC at least 50 ° C. or higher and 0 ° C. or lower as at least one component with 0.1 to 5 parts by weight of perfluoroalkane having 4 to 7 carbon atoms per 100 parts by weight of polyol. Since the foamed heat insulating material is generated by stirring, the compatibility between the low boiling point foaming agent composed of HCFC or HFC and the polyol component can be improved, and the perfluoroalkane added in a trace amount can form fine bubbles. It is possible to provide a foamed heat insulating material which forms a central core and can generate a uniform fine cell structure due to uniform foaming behavior and has excellent physical properties in thermal conductivity. In particular, it is possible to use a general hard polyurethane foam polyether polyol which is effective in reducing the thermal conductivity but has a significantly poor solubility with a low boiling point foaming agent, and the physical properties are remarkably improved. Is something that can be demonstrated.

Furthermore, HFC has an ozone depletion coefficient of 0, and not only does it have no effect on ozone depletion by itself, but it also causes ozone depletion in a mixed system with HCFC, which has some effect on ozone depletion. On the other hand, it is possible to produce an effective foam insulation material.

Further, by filling the foamed heat insulating material to form a heat insulating box, there is no problem of sweating in the void portion and deterioration of heat insulating performance, and the quality as an excellent heat insulating box can be secured. Therefore, this can contribute to the solution of global environmental problems such as ozone layer depletion due to CFC.

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Claims (4)

[Claims] 1. An organic polyisocyanate, a polyol component containing at least 5 to 25% of a hydroxyl component having the molecular structure of (Chemical Formula 1), a foam stabilizer, a catalyst, and a boiling point of −
A foaming agent containing at least one component of hydrochlorofluorocarbon at 50 ° C. or higher and 0 ° C. or lower, and a polyol 100
A foamed heat insulating material produced by foaming by mixing and stirring 0.1 to 5 parts by weight with respect to parts by weight of perfluoroalkane having 4 to 7 carbon atoms. [Chemical 1] 2. An organic polyisocyanate, a polyol component containing at least 5 to 30% of a hydroxyl component having the molecular structure of (Chemical formula 1), a foam stabilizer, a catalyst, and a boiling point of −
A blowing agent containing at least one component of hydrofluorocarbon at 50 ° C. or higher and 0 ° C. or lower, and 0.1 to 5 parts by weight of C4 to 7 per 100 parts by weight of polyol.
A foam insulation material that is foamed by mixing and stirring with a fluoroalkane. 3. An insulating box body comprising an outer box, an inner box, and the foamed heat insulating material according to claim 1, which is foam-filled in a space formed by the outer box and the inner box. 4. A heat-insulating box body comprising an outer box, an inner box, and the foam heat insulating material according to claim 2, wherein a space formed by the outer box and the inner box is foam-filled.