JPH0791818A - Heat insulating structure - Google Patents

Abstract

PURPOSE:To provide equal combustion speed to a foamed heat insulating material using conventional harogenized hydrocarbon as a foaming agent and permit the securing of non-corrosive property against a metallic pipe arranged in a structural body even when a hydrocarbon, having flamability, is employed as the foaming agent of the foamed heat insulating material. CONSTITUTION:A space in a heat insulating structure, in which a metallic pipe 5 is arranged, is filled with a foamed heat insulating material 4 produced by a method wherein organic polyisocyanate, prepolymerized by non-harogenized organic phosphor compound, having the molecular weight of 400 or less and containing active hydrogen, peviously is mixed with polyol, foam stabilizer, catalyst and a foaming agent having at least a constituent of hydrocarbon, then, the mixture is foamed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating structure used in refrigerators, frozen prefabs 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 drawing attention. From such a viewpoint, reduction of the amount of CFC used as a foaming agent has become an extremely important theme.

For this reason, it has been proposed to use a hydrocarbon containing no halogen in the molecule as a foaming agent in a rigid urethane foam which is a typical foamed heat insulating material.

For example, Japanese Unexamined Patent Publication (Kokai) No. 3-152160 describes a method for producing a polyurethane rigid foamed plastic using a combustible substance such as cyclopentane or cyclohexane as a foaming agent. Then, in the detailed description of the invention, it has been proposed to use a flame retardant as an additive in order to improve the flammability of a hard urethane foam containing the combustible substance as a foaming agent. -G and inorganic flame retardants are described as candidates.

[0005]

There is a problem of flammability in applying the above-mentioned hydrocarbon as a foaming agent, and it is not possible to fill a heat insulating wall with a foam heat insulating material containing a flammable gas before use. However, there is a danger of spread of fire during a fire, which is a major issue.

However, when using a foamed heat insulating material containing a flame retardant such as the halogen-substituted phosphate as described above, a refrigerant is circulated in a heat insulating structure filled with the foamed heat insulating material such as a refrigerator. When there is a metal pipe, it is difficult to apply due to the problem of metal corrosion. In addition, when the food is stored for a long period of time, there is a risk of toxicity such as migration through the face material. In view of the above problems, the present invention has at least the conventional C even when a flammable hydrocarbon is used as a foaming agent.
With the same burning rate as FC11 foaming, there is no danger of spreading fire during a fire, etc., and there is no problem in terms of safety when corroding metal pipes to cause refrigerant leakage or when food is stored for a long time. It is intended to provide a structure.

[0007]

In order to solve the above-mentioned problems, the present invention contains a hydrocarbon such as pentane or cyclopentane as a foaming agent and has a molecular weight of 40 in advance.
A foamed heat insulating material obtained by mixing and foaming an organic polyisocyanate prepolymerized with a non-halogenated organic phosphorus compound having an active hydrogen of 0 or less, a polyol, a foam stabilizer, and a catalyst, at least a metal pipe. The heat insulating structure is formed by injection molding in the arranged space.

[0008]

With the above structure, although the foamed heat insulating material filled in the heat insulating structure contains a combustible gas,
Combustibility of the resin part is suppressed by the effect of the organic polyisocyanate and the prepolymerized organic phosphorus compound, and the combustion rate is at least equivalent to that of conventional CFC11 foaming.
The danger of spread of fire during a fire is eliminated, and it contributes to the solution of global environmental problems such as ozone destruction and can be used safely.

Further, in advance, organic polyisocyanate
Since the organophosphorus compound and the pre-polymerized organophosphorus compound do not contain halogen, even if the heat insulating structure is incinerated at the time of disposal, it does not release halogenated substances that cause acid rain into the atmosphere and poses a problem to the environment. Can be expected to be In addition, the organic phosphorus compound used in the present invention has active hydrogen and is preliminarily reacted with the organic polyisocyanate to be prepolymerized. As a result, phosphorus is not ionized and liberated, and there is no possibility of corroding the metal pipe. Especially when a metal pipe for circulating a refrigerant is installed like a refrigerator, since the surface temperature is low at a part of the metal pipe, moisture that has entered from the outside easily condenses on the metal pipe and is easily corroded. In this situation, pre-polymerization of the organic phosphorus compound with the organic polyisocyanate can suppress the ionization of phosphorus, and the reliability can be improved in the long-term use of the product. At the same time, by pre-polymerizing the organic phosphorus compound with the organic polyisocyanate, the phosphorus component is fixed in the urethane resin, there is no migration to plastics face material, even for foods that are stored for a long time. It is possible to provide an insulating structure that does not have a problem of being contaminated and has no problem in product safety.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings of FIGS.

Reference numeral 1 denotes a heat insulating structure, which is covered with a face material 2 made of plastic such as ABS and an iron plate 3, and a foam heat insulating material 4 made of hard urethane foam is filled and arranged inside. Reference numeral 5 denotes a copper pipe for circulating a coolant, which is embedded in the foamed heat insulating material 4.

An example of the raw material formulation of the foamed heat insulating material 4 is shown in Table 1.

[0013]

[Table 1]

Polyether A is an aromatic amine-based polyether polyol having a hydroxyl value of 460 mgKOH / g, and foam stabilizer A is a silicone surfactant F-3 manufactured by Shin-Etsu Chemical Co., Ltd.
35 and catalyst A are Kaolyzer No. 35 manufactured by Kao Corporation. 1,
The foaming agent A is cyclopentane, the foaming agent B is pure water, and each raw material is mixed in a predetermined mixing number to form a polyol component. Further, the isocyanate component A is based on an organic polyisocyanate composed of crude MDI having an amine equivalent of 135 and has a molecular weight of 224 and a hydroxyl value of 250 mgKO.
An organophosphorus compound consisting of H / g of dibutylhydroxymethylphosphonate was prepolymerized by mixing 5% with Clude MDI in advance. The premix component and the isocyanate component thus prepared are mixed with a high-pressure foaming machine in a predetermined mixing number and injected into the face material 2 and the iron plate 3 in which the copper pipes 5 are arranged in advance,
The heat insulating structure 1 was obtained.

The degree of combustion of the obtained foamed heat insulating material 4 is determined by JIS.
-The burning time of the flammability test item in A9514 is also shown in Table 1 as a characteristic value.

Further, the results of analysis of the corrosion degree of the copper pipe and the phosphorus content transferred to the face material 2 when the heat insulating structure 1 was operated at 40 ° C. and 95% RH for 3 months (Table 1).
It was shown to.

At the same time, as a comparative example, a case where a crude MDI alone is used for the isocyanate B (Comparative Example A) and a case where the isocyanate C is a halogen-containing tris- (2-) for the crude MDI are used. The results obtained when 5% of chloroethyl) phosphate was added (Comparative Example B) and also when CFC11 was used as the foaming agent C (Comparative Example C) are shown in Table 1.

As described above, dibutylhydroxymethylphosphonate, which is a non-halogen-containing organic phosphorus compound having a molecular weight of 224 and active hydrogen, is preliminarily charged with
When de-MDI and prepolymerized organic polyisocyanate are used, the combustibility of the resin portion of the foamed heat insulating material 4 is suppressed even if cyclopentane, which is a combustible hydrocarbon, is used as the foaming agent. , CFC11 was used and the degree of combustion was almost the same. As a result,
The danger of spread of fire during a fire is eliminated, and it contributes to the solution of global environmental problems such as ozone destruction, and at the same time the product can be used safely. And, dibutyl hydroxymethyl phosphonate is previously reacted with the organic polyisocyanate, as a result of prepolymerization,
Phosphorus was not ionized and released to corrode the metal pipe. In particular, there was no problem even when moisture entering from the outside was condensed on the copper pipe 5 under a high humidity condition to easily corrode. That is, it was found that pre-polymerization with the organic polyisocyanate can suppress the ionization of phosphorus and can enhance the reliability in the long-term use of the product.

Furthermore, it was found that phosphorus transfer to the face material 2 of the plastics was not detected, and even when the food was stored for a long period of time, it was not contaminated and a heat insulating structure having no problem in product safety can be provided. It was

On the other hand, in the case of using the single MUD as a comparative example (Comparative Example A), there is a phenomenon that the combustion speed becomes higher than that in the case of using CFC11, which is difficult to apply. When an organic polyisocyanate obtained by adding tris- (2-chloroethyl) phosphate containing halogen to the crude MDI was used (Comparative Example B), the corrosion of the copper pipe 5 was large and the surface material 2
It is also difficult to apply due to problems such as detection of phosphorus transfer to

[0021]

As described above, the present invention contains a hydrocarbon such as pentane or cyclopentane as a foaming agent and is prepolymerized with a non-halogenated organophosphorus compound having a molecular weight of 400 or less and active hydrogen. In order to form a heat insulating structure by injection molding a foam heat insulating material obtained by mixing and foaming an organic polyisocyanate, a polyol, a foam stabilizer and a catalyst into a space in which at least a metal pipe is arranged, a foam heat insulating material is formed. Although the material contains a combustible gas, at least the conventional CFC is obtained by the effect of the organic polyisocyanate and the prepolymerized organic phosphorus compound.
The burning rate is the same as that of No. 11 foaming, and there is no danger of spreading fire during a fire, contributing to the solution of global environmental problems such as ozone destruction, and at the same time, it can be used safely.

Further, since the organic polyisocyanate and the prepolymerized organophosphorus compound do not contain halogen, halogenated substances which cause acid rain even if the heat insulating structure is incinerated at the time of disposal are exposed to the atmosphere. It can be expected that there will be no problem for the environment without being released into the environment. And, in advance, the organic phosphorus compound having active hydrogen,
Since an organic polyisocyanate and a prepolymerized one are applied, they react with the organic polyisocyanate as a raw material and become more polymerized.As a result, phosphorus is ionized and released even when the metal pipe is placed in the foamed heat insulating material. Therefore, there is no possibility of corroding the metal pipe and the reliability can be improved in the long-term use of the product. Further, it is possible to provide a heat insulating structure which does not cause plastics to be transferred to a face material and is not contaminated even when food is stored for a long period of time and has no problem in product safety.

[Brief description of drawings]

FIG. 1 is a perspective view in which a heat insulating structure according to an embodiment of the present invention is partially cut away.

FIG. 2 is a sectional view of a heat insulating structure according to an embodiment of the present invention.

[Explanation of symbols]

 1 Heat insulation structure 4 Foam insulation 5 Metal pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // (C08G 18/10 101: 00) C08L 75:04 (72) Inventor Tomonoh Ama Osaka Prefecture 3-22, Takaidahondori, Higashiosaka-shi Matsushita Cold Machinery Co., Ltd.

Claims (1)

[Claims] 1. An organic polyisocyanate prepolymerized with a non-halogenated organophosphorus compound having a molecular weight of 400 or less and having active hydrogen, and a polyol, a foam stabilizer, a catalyst, and at least pentane and cyclopentane. A heat insulating structure in which a foam insulating material obtained by mixing a foaming agent containing hydrocarbon as one component and foaming is filled in at least a space in which a metal pipe is arranged.