JPH087650A - Insulating sheet for compressor in refrigerator - Google Patents

Abstract

PURPOSE:To provide an insulating sheet excellent in stability and workability by layering synthetic fiber paper, which is composed of only hydrophobic synthetic fiber excellent in heat resistance and hydrolysis resistance, on both surfaces of a heat resistant synthetic resin film. CONSTITUTION:Synthetic fiber paper 2 (in which a binder or the like is not used) composed of only hydrophobic synthetic resin fiber more excellent in heat resistance and hydroysis resistance than a film 1, is layered on both surfaces of the heat resistant synthetic resin film 1 by fusion by heating and pressurization. Layering by an adhesive also becomes possible instead of layering by the fusion. Since the binder is not used in the synthetic fiber paper, tensile strength of itself is low, but sufficient tensile strength can be guaranteed to the whole layered sheet. When thicknesses of the film and the synthetic fiber paper are mutually adjusted, proper rigidity can be applied to the layered sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating sheet used for insulating a motor in a compressor of a refrigerator.

[0002]

2. Description of the Related Art In an air conditioner or an industrial refrigerator, a refrigerant is evaporated in an evaporator by heat absorption from an object to be cooled,
This is compressed by a compressor to raise the temperature and pressure, further liquefied by heat dissipation in a condenser, expanded by an expansion valve and then sent to the evaporator again. The refrigeration cycle is repeated by the refrigerant circulation system. ing. In this case, refrigerating machine oil is added to the refrigerant in order to prevent wear of mechanical parts in the circulation system.

In this refrigerating compressor, the refrigerant is pressurized, condensed and discharged at a high temperature. Therefore, the insulating material of the motor incorporated in the compressor can withstand such high pressure and high temperature. You have to use one.

Conventionally, CFC (chlorofluorocarbon) -12, HCFC (hydrochlorofluorocarbon) -32 and the like have been used as the above-mentioned refrigerants, but recently, the ozone layer of these CFC compounds is depleted. Since the destruction of the global environment due to the phenomenon has become a problem on a global scale, the development of alternative refrigerants has been promoted.

The conditions required for this alternative refrigerant are:
In addition to having an ozone depletion potential and a global warming potential of 0 to very small, a high refrigerating capacity and a low condensation pressure and discharge temperature are required.

However, it is not easy to satisfy these conditions with a single refrigerant, and HFC-32 (CH ₂
F ₂ ), HFC-125 (CHF ₂ CF ₃ ), HFC-1
The use of composite refrigerants such as 34a (CH ₂ FCF ₃ ) has been proposed. Condensing pressure by the compressor for this composite refrigerant,
The discharge temperature is the same as that of the conventional refrigerant (CFC-12, HCFC-2
2)) and the insulation of the motor of the compressor is
At least 13 under a pressure of 25-35 kg / cm ^2.
Heat resistance of 0 ° C or higher is required.

Therefore, it has been proposed to use a polyethylene terephthalate film, a polyethylene naphthalate film, a polyphenylene sulfide film, a polyimide film or the like which is a low content oligomer as an insulating film material for the motor.

[0008]

As described above, in the refrigerating and circulatory system, it is necessary to add lubricating oil to the refrigerant in order to prevent wear of the mechanical parts. This lubricating oil is dissolved in the refrigerant and heated, Since cooling is repeated, it is necessary to use a material that can guarantee compatibility and insulation with the refrigerant even under such heating and cooling. Therefore, the above HFC
Polyalkylene glycol, polyol ester, carbonate type and the like are suitable as the lubricating oil for the composite refrigerant such as -32, HFC-125 and HFC-134a.

However, these oils have remarkably high hygroscopicity as compared with the conventional mineral oil type oil (for example, while the saturated oil content of the mineral oil type is 50 ppm or less, for example, the saturated water content of the polyol ester type is used). The amount is 2000pp
m or more), the above-mentioned low-content oligomer polyethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film or polyimide film, etc., under contact with a mixed liquid of the lubricating oil and the composite refrigerant. The decrease in mechanical strength is remarkable.

For example, the low content oligomer-polyethylene terephthalate film is mixed with the composite refrigerant and the polyolefin.
The polyethylene terephthalate film had a residual elongation of 0% and a residual tensile strength of almost 50% when it was immersed in a mixed solution with luster oil under a water absorption of 1000 ppm for 500 hours.

Obviously, such a decrease in mechanical strength is accompanied by a decrease in electrical strength, and unless such a problem is solved, the above low content oligomer-polyethylene terephthalate film and polyethylene naphthalate film are included. It is not possible to use a polyphenylene sulfide film, a polyimide film, or the like as an insulating material for a compressor of a refrigerator of the above mixed refrigerant / lubricating oil system.

Therefore, the inventors of the present invention have made a thorough investigation into the cause of the deterioration of the low content oligomer-polyethylene terephthalate film or the like with respect to the composite refrigerant / lubricating oil mixture under a high water absorption amount. Has been found to be due to hydrolysis, and it has been found that improving the hydrolysis resistance of the insulating material is effective for solving the above problems.

However, in view of the molecular structure of the resin, the hardness of the resin also increases as the hydrolysis resistance (chemical stability) of the resin increases, and with such a hard resin film, the work of insulating treatment of the motor becomes extremely difficult. . If a resin having excellent hydrolysis resistance is used in the form of paper, the workability during the insulation treatment can be guaranteed, but the hydrolysis deterioration of the binder of the fiber becomes a problem.

The objects of the present invention are HFC-32, HFC-
125, HFC-134a and other composite refrigerants and polyalkylene glycol, polyol ester or carbon
An insulating sheet for a compressor in a refrigerator, which has excellent stability even when used for insulation of a compressor for mixed refrigeration with a lubricating oil such as a hot oil, and which can sufficiently guarantee workability during insulation treatment. To provide.

[0015]

Means for Solving the Problems An insulating sheet for a compressor in a refrigerator according to the present invention comprises a heat-resistant synthetic resin film on both sides of which a hydrophobic property superior in heat resistance and hydrolysis resistance to the film. The synthetic resin paper consisting only of the synthetic resin fibers is laminated, and the heat-resistant synthetic resin film is a polyethylene terephthalate film, a polyethylene naphthalate film, a polyphenylene sulfide film or a polyimide film. Any of the above is preferably used, and the synthetic resin fiber is preferably polyarylate fiber.

The present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an insulating sheet according to the present invention. In FIG. 1, 1 is a polyethylene terephthalate film having a low oligomer content, and polyethylene naphthalate.
Film, a polyphenylene sulfide film, a heat-resistant synthetic resin film such as a polyimide film, and commercially available products such as Toray's Lumira-X10 film (polyethylene terephthalate film with low oligomer content), Teijin Teonex film (polyethylene naphthalate film) manufactured by Toray DuPont Co., Ltd. Kapton film (polyimide film) manufactured by Toray DuPont.
Etc.

Reference numeral 2 is a synthetic fiber paper (no binder or other third component is used) which is composed of only hydrophobic synthetic resin fibers which are more resistant to hydrolysis than the film 1. By heating and pressurizing on both sides (usually,
The layers are laminated by fusion at 250 ° C. to 300 ° C. and a pressure of 40 to 60 kg / cm ² .

The synthetic fiber paper was obtained by spinning a molten liquid crystal polymer of polyarylate (a wholly aromatic polyester which is a copolymer of hydroxynaphthoic acid and hydroxybenzoic acid) under high orientation. The fiber can be produced by utilizing the dispersion and water retention property of the fiber without using a binder or a third component, and as a commercial item, there is Veculus CC-50 type manufactured by Kuraray Co., Ltd.

Instead of the above-mentioned fusion-bonding lamination, it is also possible to laminate using an adhesive. As this adhesive, HFC-3 is used.
2. Under contact with a mixed liquid of a composite refrigerant such as HFC-125 or HFC-134a and a lubricating oil such as polyalkylene glycol, polyol ester or carbonate, under a temperature of about 130 ° C. However, a material that is stable for a long period of time, such as an epoxy resin or a phenol resin resin, is used, and the coating amount of the adhesive is usually about 7 to 10 g / m ² .

In the present invention, the synthetic fiber paper consisting only of hydrophobic synthetic resin fibers having excellent hydrolysis resistance serves to prevent moisture from coming into contact with the heat-resistant synthetic resin film due to the hydrophobicity of the fibers. And the basis weight is 30 to 70 g / m
It is appropriate to set it to ² (if it is 30 g / m ² or less, it is difficult to fulfill its function satisfactorily, and if it is 70 g / m ² or more, papermaking becomes difficult).

In the present invention, the heat-resistant synthetic resin film has a thickness of 0.05 to 0.15 mm (0.05
If it is less than mm, the thickness of the whole laminated sheet becomes too thin,
It is necessary to increase the number of inserts, etc., during the slot insulation process, resulting in poor workability. When the thickness is 0.15 mm or more, the flexibility of the laminated sheet is insufficient, and it is difficult to guarantee workability during insulation treatment), and the thickness of the synthetic fiber paper is 0.03 mm to 0.08 m.
m (0.03 mm or less, the overall thickness of the laminated sheet becomes too thin, and the number of inserted sheets during insulation treatment must be increased, resulting in poor workability. Difficult to make).

In the refrigerator, the insulating sheet according to the present invention is used as a refrigerator refrigerant such as HFC-32 and HFC-12.
5, HFC-134a, etc., with polyalkylene glycol
It is used as a core insulation, interphase insulation, especially as a liner insulation material of the motor of a hermetic compressor when a refrigerating machine oil such as a polyol, polyol ester or carbonate is mixed and circulated and used. , The condensing pressure of the refrigerant in this case is 25 to 35
The discharge temperature is about 130 ° C. and kg / cm ² .

[0023]

In the synthetic fiber paper, fibers having excellent hydrolysis resistance are produced without using a third component such as a binder, and thus have excellent hydrolysis resistance. HFC-32, HFC-125, HFC as refrigerator refrigerant
In a mixed liquid of -134a and the like with a polyalkylene glycol, a polyol ester or a carbonate type as a refrigerating machine oil, the water absorption of the refrigerating machine oil is high, so that the water absorption amount is 1000 ppm to 2000 ppm. However, due to the hydrophobic nature of the synthetic fiber paper, the contact of water in the mixture with the heat resistant synthetic resin film is eliminated. Therefore, the heat-resistant synthetic resin film is protected from hydrolysis by the synthetic fiber paper on both sides thereof, and even if the intermediate synthetic resin film has a low hydrolysis resistance, the laminated sheet as a whole has sufficient hydrolysis resistance. Can be very expensive.

Since the synthetic fiber paper does not use a binder, the tensile strength of the synthetic fiber paper itself is low. However, since the synthetic fiber paper is laminated with the heat-resistant synthetic resin film as the core material, the whole laminated sheet is used. With respect to, a sufficient tensile strength can be guaranteed. Furthermore, by adjusting the thickness of the hard heat-resistant synthetic resin film and the thickness of the flexible synthetic fiber paper to each other,
It is possible to impart appropriate rigidity to the laminated sheet with an appropriate thickness. Therefore, from these points, it is possible to ensure good workability during insulation treatment.

[0025]

【Example】

Example 1 A heat-resistant synthetic resin film has a heat resistance of B
Lumira-X10 type, a low-oligomer polyethylene terephthalate film manufactured by Toray Industries, Inc., with a thickness of 0.
125 mm is used, and the hydrolysis resistant hydrophobic synthetic fiber paper is a polyarylate fiber paper manufactured by Kuraray Co., Ltd.
Beckles' CC-50 type, thickness of 0.05 mm was used. The lamination was performed by fusion, and the fusion conditions were a pressure of about 50 kg / cm ² , a temperature of about 280 ° C. and a pressurizing time of about 1 minute.

Examples 2 to 4 As synthetic fiber paper, polyethylene naphthalate film [Teonex film manufactured by Teijin Ltd.] was used in Example 2, and polyphenylene sulfide film was used in Example 3. Example 4 was the same as Example 1 except that each polyimide film was used.

The following deterioration tests were conducted on the products of these Examples. That is, HFC-32 / HFC-125
/ HFC-134a at a ratio of 23/25/52 to 100 parts of the composite refrigerant, polyalkylene glycol compatible with them is mixed at a volume ratio of 95.5 parts, and the mixed liquid has a water absorption amount. The sample was immersed in 1000 ppm for 500 hours, and the elongation residual ratio (%) and tensile strength residual ratio (%) of each Example product after the lapse of 500 hours were measured. The results were as follows. Example 1 Example 2 Example 3 Example 4 Elongation residual rate (%) 80-85 85-90 85-90 90-95 Tensile strength residual rate (%) 85-90 90-95 90-95 90-95

[Examples 5 to 8] The heat-resistant synthetic resin film and the hydrolysis-resistant hydrophobic synthetic fiber paper were prepared from Examples 1 to 8.
The same thing as that of No. 4 was used [The heat-resistant synthetic resin film of Example 5 was that of Example 1, that of Example 6 was that of Example 2 and that of Example 7 was that of Example 3] In Example 8, each of Example 4 was used]. On both sides of each heat-resistant synthetic resin film,
Apply ISOOPY varnish evenly and dry at 100 ° C for 10 to 15 minutes to form an adhesive layer (adhesive amount is 7-9g per side)
/ M ² ), and then dispose the above-mentioned synthetic fiber paper on both sides of each heat-resistant synthetic resin film, pass through a metal roll at a temperature of 130 ° C. and a pressure (linear pressure) of 100 kg / cm, and finally Then, curing was performed at 150 ° C. for 5 hours.

With respect to these examples, the deterioration test was conducted in the same manner as described above, and the residual elongation (%) and the residual tensile strength (%) were measured. The results are as follows. Example 5 Example 6 Example 7 Example 8 Elongation residual rate (%) 80 to 85 80 to 85 85 to 90 75 to 80 Tensile strength residual rate (%) 90 to 95 90 to 95 90 to 95 80 to 85

With respect to the above examples, only the above heat resistant synthetic resin films were subjected to the deterioration test in the same manner as above and the residual elongation (%) and the residual tensile strength (%) were measured. Also in heat resistant synthetic resin film,
Residual elongation (%) is almost 0, residual tensile strength (%) is 50
% Or less.

As is clear from these test results, according to the insulating sheet for a refrigerating compressor of the present invention, polyethylene terephthalate, which is the core material, even if the water content in the refrigerant is high.
It is possible to sufficiently prevent hydrolysis of a heat-resistant film such as a heat-resistant film and sufficiently exhibit its excellent insulating property.

Further, in the insulating sheet of the present invention, a polyethylene terephthalate film or the like having an appropriate rigidity is used for the core material, which is excellent in mechanical strength.
It is suitable as a liner material for an iron core slot, and when the insulating sheet of each of the above-mentioned embodiments is actually inserted into the iron core slot of a motor and a winding is attached to the slot, work can be performed with good workability. did it.

[0033]

INDUSTRIAL APPLICABILITY The insulation sheet of the present invention is used for insulating the motor of a compressor in a refrigerator, and has an ozone depletion potential and a global warming potential of 0 to very little as a refrigerator refrigerant. Small, HFC-32, HFC-125, HFC
-134a and the like, even when used with a refrigerating machine oil such as polyalkylene glycol, polyol ester or carbonate type, which is compatible with these refrigerants, due to the high water absorption of the refrigerating machine oil. In addition, it is possible to sufficiently avoid hydrolysis deterioration that cannot be avoided with conventional insulating materials. Therefore, in the refrigerator, the present invention uses HFC-32, HFC-125, and HFC-1 which are essential for ozone depletion and prevention of global warming.
34a and these non-azeotropic mixed refrigerant systems are extremely useful.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an insulating sheet according to the present invention.

[Explanation of symbols]

 1 Heat-resistant synthetic resin film 2 Synthetic fiber paper

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[Procedure amendment]

[Submission date] July 29, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

Conventionally, the above-mentioned refrigerant, CFC (chlorofluorocarbon) -12 and HCFC (hydrochlorofluorocarbon) - but 22 or the like have been used, recently, global environmental destruction by ozone depletion of these flon compounds Earth Due to the problem of scale, alternative refrigerants are being developed.

Claims (2)

[Claims] 1. A refrigerator comprising a heat-resistant synthetic resin film laminated on both sides with a synthetic fiber paper consisting of only hydrophobic synthetic resin fibers having better heat resistance and hydrolysis resistance than the film. Insulation sheet for compressor in. 2. The heat resistant synthetic resin film is any one of a polyethylene terephthalate film, a polyethylene naphthalate film, a polyphenylene sulfide film or a polyimide film, and the synthetic resin fiber is a polyarylate fiber. An insulating sheet for a compressor in the refrigerator according to 1.