JPH05306880A - Heat insulating box body employing hard polyurethane - Google Patents

Abstract

PURPOSE:To improve heat insulating property and adhesive property by a method wherein at least three kinds of polyether polyol initiators having different molecular weights and different numbers of functional group are employed while a predetermined mixture is used as foaming agent. CONSTITUTION:A gap between an outer casing and an inner casing is filled with hard polyurethane foam formed by reacting polyol and isocyanate under the existence of a foaming agent. In this case, the initiator of polyol is the mixture. of 20-70 pts.wt. of aliphatic initiator having average functional groups of 2-4, 15-60 pts.wt. of initiator having average number of functional groups 3-5 and 65 pts.wt. of aliphatic amin initiator having 3-5 average functional groups. A predetermined polyol, obtained by adding the mixture with alkylene oxide, is employed. The mixture of monochlorodifluoromethane, 1-chloro-1, and 1-difluoroethane is employed as a foaming agent while foaming molding is effected by setting the mixing ratio of the same within a predetermined range whereby the heat insulating box body can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-insulating box body using a refrigerator or a showcase, and in particular, it is a hard material capable of obtaining good performance without using regulated CFC as a foaming agent used in the production of urethane foam. An object is to provide an insulating box body using polyurethane foam.

[0002]

2. Description of the Related Art Generally, a heat insulating box constituting a refrigerator or the like has a foaming agent containing a polyol component and an isocyanate component between an outer box and an inner box as shown in, for example, Japanese Utility Model Publication No. 60-11430. Formed by filling a rigid polyurethane foam which is reacted in the presence of Here, the rigid polyurethane foam is usually obtained by reacting a polyol component and an isocyanate component in the presence of a foaming agent, a reaction catalyst, and a foam stabilizer. In general, a rigid polyurethane foam having closed cells can obtain excellent heat insulating property with good productivity, and therefore, as the above-mentioned foaming agent, the thermal conductivity of gas is extremely small, and it has a low boiling point and is a liquid at room temperature, nonflammable and low Trichloromonofluoromethane (R11), which has excellent properties such as toxicity, is commonly used. (See JP-A-62-81414)

[0003]

However, there is a problem as described below due to the above configuration, and an urgent countermeasure is demanded.

Trichloromonofluoromethane (R11), which is commonly used as a foaming agent in the above-mentioned prior art, is a persistent CFC (Chloro Fluoro Carbon).
Is an abbreviation for chlorofluoro-substitution of hydrocarbons, and it is said that if this kind of persistent CFC is released into the atmosphere, it will adversely affect the ozone layer in the stratosphere and raise the surface temperature due to the greenhouse effect. In recent years, it has become a global environmental pollution problem, and the movement to regulate the production and consumption of these persistent CFCs is increasing.

Therefore, the selection of alternatives is being promoted worldwide, and as the blowing agent, for example, 1,1-dichloro-2,2,2trifluoroethane (R
123) came up as the most promising candidate.

However, the above 1,1-dichloro-2,2
2 Trifluoroethane (R123) has a drawback that the thermal conductivity of gas is about 10% larger than that of conventional trichloromonofluoromethane (R11), and when it is used for a rigid polyurethane foam, it has a poor heat insulating property. Further, since the boiling point is high, the reactivity becomes slow, and the compressive strength and the dimensional stability are lowered, and further, the physical properties are lowered such that the demolding time is lengthened.

Therefore, a foaming technology using a mixture of chlorodifluoromethane (R22) and 1-chloro-1,1-difluoroethane (R142b) as a foaming agent which is a non-regulated refrigerant and has a low boiling point and which can be expected to have a certain heat insulating property. Research has begun. However, this mixed refrigerant foam
Compared to the conventional foaming using R11, there is a problem that the mixing property with the polyether polyol is poor, the gas is easily scattered during the foaming, and the heat insulation of the urethane foam is poor. That is, the thermal conductivity of such a foam is currently about 0.0165 kcal / mh ° C. (23.8 ° C. average temperature), and for example, refrigeration that requires maintaining the temperature inside the refrigerator at about −20 ° C. The equipment radiated a lot of heat and could not be put to practical use.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat insulating box body using a rigid polyurethane foam excellent in heat insulating property and adhesiveness without using a restriction CFC. .

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a heat-insulating box body filled with a rigid polyurethane foam formed by reacting a polyol and an isocyanate in the presence of a foaming agent between an outer box and an inner box. In the rigid polyurethane foam, the initiator of the polyol is an aliphatic type and has an average number of functional groups of 2 to 4, 20 to 70 parts by weight, and an average number of functional groups of 3 to
5 to 15 parts by weight of aromatic amine-based compounds having an average number of functional groups of 3 to 5 and 65 parts by weight or less,
A polyol having a hydroxyl value of 350 to 500 mg KOH / g obtained by adding alkylene oxide to this mixture is used, and monochlorodifluoromethane and 1 are used as a foaming agent.
A mixture of -chloro-1,1-difluoroethane having a mixing ratio of 35% by weight or more of monochlorodifluoromethane is used in an amount of 5 to 55 parts by weight per 100 parts by weight of the polyol to form a heat insulating box. It was formed.

[0010]

The rigid polyurethane foam of the present invention having the above-mentioned constitution uses a special mixture as a polyol and a mixture of chlorodifluoromethane and 1-chloro-1,1-difluoroethane as a foaming agent, and has a heat insulating property and an adhesive property. An excellent rigid polyurethane foam can be molded. That is, by using at least three kinds of polyether polyol initiators having different molecular weights and functional groups in the polyether polyol, while exhibiting the low viscosity and high adhesiveness which are the advantages of the properties of each polyether polyol initiator. , The disadvantages such as the scattering loss of the foaming agent and the delay of the reaction rate can be mutually compensated, and the thermal conductivity is 0.0145 kcal / mh ° C.
(23.8 ° C. average temperature) A heat insulating box having a hard polyurethane foam having a high heat insulating performance is obtained. For this reason, it is possible to contribute to environmental protection without using regulated CFC, and other conventional auxiliary agents such as foam stabilizers and flame retardants can be used as they are. It can be used as it is for foam molding.

That is, as the blowing agent, a mixture of monochlorodifluoromethane and 1-chloro-1,1-difluoroethane having a mixing ratio of monochlorodifluoromethane 35
5% by weight or more per 100 parts by weight of polyol is 5
By using ~ 55 parts by weight, 1-chloro-1,1-
The handling of monochlorodifluoromethane can be facilitated while keeping difluoroethane in the non-flammable range.

Further, the solubility of 1-chloro-1,1-difluoroethane in a resin solution can be improved by using an aliphatic polyol initiator having an average number of functional groups of 2 to 4.

Although there is a problem that the reactivity is lowered due to the incorporation of the above-mentioned low functional group polyol initiator, the polyol initiator having an average functional group number of 3 to 5 and the aromatic amine type having an average functional group number of 3 to 5 have a problem. The polyol initiator can improve the heat insulating property by improving the reactivity and decreasing the cell diameter, and can also improve the resin strength by densifying the molecular structure, and can improve the foam shrinkage at -30 ° C. It is possible to prevent the occurrence and improve the low temperature dimensional stability.
It is possible to suppress the gas escape at the temperature of ℃, prevent the generation of shrinkage, and improve the gas aging property.

Here, if the amount of the initiator of the aliphatic type having an average number of functional groups of 2 to 4 is less than 20 parts, the viscosity and activity of the polyol become strong, and if it exceeds 70 parts, the dimensional stability and the heat insulating performance are deteriorated. , Neither is practical. Average number of functional groups 6 ~
When the amount of the polyol initiator of No. 8 is less than 15 parts, the dimensional stability is deteriorated, and when it exceeds 60 parts, the heat insulation performance is deteriorated, and neither is practical. Aromatic amine based average number of functional groups 3 to
When the amount of the initiator of No. 5 exceeds 65 parts, the adhesiveness is deteriorated and it is not practical.

The hydroxyl value of the polyol is 350 mgKO
When it is less than H / g, the dimensional stability is significantly deteriorated, and 50
If it exceeds 0 mgKOH / g, the adhesiveness and the compatibility with isocyanate are deteriorated, and neither is practical.

Monochlorodifluoromethane (R22)
Has a boiling point of −41 ° C. and a steam thermal conductivity of 0.0091 Kcal.
/ Mhr ° C., a vapor pressure 9.5 kg / cm ² at 21 ° C., has a characteristic of non-flammable gas, 1-chloro-1,1-difluoroethane (R142b) has a boiling point of -9 ° C., the vapor thermal conductivity 0. It has the characteristics of flammable gas and vapor pressure of 3.1 Kg / cm ² at 0095 Kcal / mhr ° C. and 21 ° C.

Considering the high-pressure gas regulation law and ease of handling, it is desirable to use R142b alone.
Since R142b is a flammable gas, it is necessary to drastically change the existing equipment. Therefore, by mixing R142b and R22 in a predetermined ratio, R142b can be maintained in the non-combustible region. That is, R22 in the mixed foaming agent is 3
If it is less than 5% by weight, the nonflammable region is not maintained and it is not practical.

The amount of the mixed foaming agent used is 100 mol of the polyol.
If it is less than 5 parts per part, there is no effect, and if it exceeds 55 parts, the dimensional stability deteriorates, and neither is practical.

[0019]

EXAMPLES Generally, the reaction formula for foaming a rigid polyurethane foam is as follows: R-OH + R'-NCO → R-NH-COOR 'where R-OH: polyether polyol R'-NCO : Isocyanate R-NH-COOR ': Rigid Polyurethane Conventionally, R-11 was used as a foaming agent to dilute the polyether polyol to lower the viscosity of the polyether polyol, and the heat of reaction between the polyether polyol and the isocyanate was used. Then, R-11 is gasified and enclosed in the foam to form a rigid polyurethane foam.

On the other hand, in the present invention, no regulated CFC including R-11 is used and a mixture of chlorodifluoromethane (R22) and 1-chloro-1,1-difluoroethane (R142b) is used as a foaming agent. Along with the initiator of polyether polyol, 20 to 70 parts by weight of an aliphatic type having an average number of functional groups of 2 to 4 and an average number of functional groups of 3 to 5
A mixture of 15 to 60 parts by weight of aromatic amine and an average functionality of 3 to 5 and 65 parts by weight or less of an aromatic amine, and a hydroxyl value obtained by adding alkylene oxide to the initiator mixture of 350 to 500 mg KOH / g of the polyol and the above mixture as a foaming agent having a mixing ratio of 35% by weight or more of monochlorodifluoromethane,
Foam molding was performed using 5 to 55 parts by weight per 100 parts by weight of the polyol.

Specifically, it is as follows.

Polyol: Sucrose, pentaerythritol, toluenediamine, and glycerin 4: 2:
Hydroxyl value 450 mg KOH obtained by adding propylene oxide to a mixture of initiators mixed in a ratio of 2: 2
/ G Polyol Isocyanate: Cosmonate M-200 Mitsui Toatsu Chemical Co., Ltd. product Polymek MDI NCO 31.3% All known organic polyisocyanates can be used, but the most common one is toluene diisocyanate (TDI). And diphenylmethane diisocyanate (MDI). TDI is a mixture of isomers, namely 2,
4-body 100% product, 2,4-body / 2,6-body = 80/2
0,65 / 35 (polymerization ratio), Mitsui Cosmonate TRC, Takeda Pharmaceutical's Takenate 40
So-called crude TDI containing a polyfunctional tar known as 40 etc. can also be used. Also, for the MDI,
In addition to pure products containing 4,4'-diphenylmethane diisocyanate as the main component, Polymec MDIs such as Mitsui Cosmonate M-200, which is a trade name containing polyhedra with three or more nuclear bodies, and Millionate MR from Takeda Pharmaceutical Co., Ltd. are used. it can. The organic polyisocyanate and NC of active hydrogen in the resin solution described later
O / H (active hydrogen) = 0.70 to 5.00 (equivalent ratio) is particularly suitable.

Catalyst: Kao Co., Ltd. Kaolizer N
O. As the 1 (tetramethylhexamethylenediamine) catalyst, amine-type urethane-forming catalysts such as triethylamine, tripropylamine, and tetramethylhexamethylenediamine can be used in addition to the above.

These catalysts can be used alone or as a mixture, and the amount thereof used is that of the compound 10 having active hydrogen.
0.0001 to 10.0 parts is suitable for 0 part.

Foam stabilizer: Nippon Unicar Co., Ltd. product SZ-
1653 As the foam stabilizer, a known organosilicon surfactant is used. In addition to the above, for example, L-5 manufactured by Nippon Unicar Co., Ltd.
420, SZ-1645, F- manufactured by Shin-Etsu Chemical Co., Ltd.
343, F-348, etc. are suitable.

The amount of the foam stabilizer used is 0.1 to 10 parts based on 100 total of the compound having active hydrogen and the organic polyisocyanate.

In addition, flame retardants, plasticizers, stabilizers, and colorants are added as needed.

Then, a predetermined amount of the above polyether polyol, catalyst, foam stabilizer, water and foaming agent is prepared in a closed container,
The liquid was transferred to a high-pressure foaming machine in a hermetically sealed state to obtain a resin. Resin and organic polyisocyanate (Cosmonate M-20
The liquid of 0) was adjusted to 20 ° C and the discharge amount of the high-pressure foaming machine was adjusted to 30
The foaming liquid of the resin and the organic polyisocyanate was injected into the space inside the box (the metal outer box and the ABS resin inner box) at a predetermined rate described below, and the mold was removed after 7 minutes.

Here, the compounding ratio of the above compound is 125 for the isocyanate (Cosmonate M-200) and 4. for the catalyst when the polyether polyol is 100.
0, foam stabilizer 1.5, water 0.4, R-22 12, R
-142b is 18 parts by weight.

The obtained rigid polyurethane foam has a thermal conductivity of 0.0145 kcal / mh ° C. (23.8 ° C. average temperature), a free foam density of 27.2 kg / m ³ , a reactivity of 40 seconds, and a low-temperature dimensional stability. Is max-0.5% (-3
The dimensional change at 0 ° C. for 48 hours), the demolding time for about 7 minutes, and the adhesiveness was good.

According to the above-mentioned examples, the rigid polyurethane foam obtained by the formulation of the present invention does not impair the general characteristics as compared with the conventional polyurethane containing a large amount of R-11,
It has been found that they exhibit almost the same excellent dimensional stability, heat insulation performance and adhesiveness.

That is, the rigid polyurethane foam of the present embodiment has the above-mentioned constitution and uses a special mixture in the polyol, and uses chlorodifluoromethane (R22) and 1-chloro-1,1-difluoroethane (R142b) as the blowing agent.
A rigid polyurethane foam having excellent heat insulating properties and adhesiveness can be molded using the mixture of For this reason,
It can contribute to environmental protection without using regulated CFCs, and other auxiliary agents such as foam stabilizers and flame retardants can be used as they are, and the existing foaming machines can be used as they are. Can be foam-molded. In addition, the control liquid temperature of the foaming machine is 25
It can be used even at 30 ° C. or higher, and the effect of further lowering the viscosity and reducing the amount of catalyst used can be obtained.

Further, when foaming the above-mentioned rigid polyurethane foam, by foaming and injecting it between the inner box and the outer box constituting the heat insulating box body, the heat insulating property and the strength are excellent, and moreover, not only the regulated refrigerant but also the unregulated refrigerant. Without even using
It is possible to form a heat-insulating box, and it can be applied to products such as refrigerators that consume a lot of CFCs.

[0034]

As described above, according to the present invention, a special mixture is used as a polyol, and a mixture of chlorodifluoromethane (R22) and 1-chloro-1,1-difluoroethane (R142b) is used as a blowing agent. It is possible to mold a rigid polyurethane foam having excellent heat insulation and adhesiveness. For this reason, it is possible to contribute to environmental protection without using regulated CFC, and other conventional auxiliary agents such as foam stabilizers and flame retardants can be used as they are. It can be used as it is for foam molding.

Further, when foaming the above-mentioned rigid polyurethane foam, by foaming and injecting it between the inner box and the outer box constituting the heat insulating box body, the heat insulating property and strength are excellent, and in addition to the regulated refrigerant, the unregulated refrigerant is also used. Without even using
It is possible to form a heat-insulating box, and it can be applied to products such as refrigerators that consume a lot of CFCs.

Since both of the refrigerants used as the foaming agent are low boiling point refrigerants, the reaction heat peculiar to urethane generated during foaming can be suppressed, and the demolding time can be shortened.

By increasing the ratio of R142b relative to R22, the gas aging property is further improved, and the sealing property of the heat insulating box body with respect to the face material (both the metal outer box and the ABS resin inner box) is improved. Can be simplified.

Further, since the above mixture is adopted as the polyether polyol, each good characteristic part can be utilized, and the reaction rate can be controlled without using a special catalyst.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area C08L 75:04

Claims (1)

[Claims] 1. A heat-insulating box body filled with a rigid polyurethane foam formed by reacting a polyol and an isocyanate in the presence of a foaming agent between an outer box and an inner box,
In the rigid polyurethane foam, the polyol initiator is an aliphatic type and has an average number of functional groups of 2 to 4 20 to 7
0 parts by weight, 15-60 parts by weight having an average number of functional groups of 3 to 5, and 6 of aromatic amines having an average number of functional groups of 3 to 5
It is a mixture of 5 parts by weight or less, and a hydroxyl value of 350 to 500 obtained by adding alkylene oxide to the mixture.
Using a polyol of mgKOH / g, a mixture of monochlorodifluoromethane and 1-chloro-1,1-difluoroethane having a mixing ratio of 35% by weight or more of monochlorodifluoromethane as a foaming agent is used as the polyol 10
A heat-insulating box body using a rigid polyurethane foam, characterized in that it is foam-molded in an amount of 5 to 55 parts by weight per 0 parts by weight.