JPH0835562A - Head gasket or muffler gasket for compressor of refrigerator - Google Patents

Abstract

PURPOSE:To sufficiently maintain the airtightness of each part, secure excellent strength and durability, and dissolve the generation of precipitated substance, by using the fluorinated hydrocarbon group refrigerant and using the ester group synthetic lubricating oil as refrigerator oil used together with the refrigerant, without using asbestos. CONSTITUTION:Each constitution of a head gasket for compressor of a refrigerator or a muffler gasket consists of at least inorganic charging material other than asbestos, polycarbodiimide resin, fiber components consisting of organic or inorganic fibers, and the hydrogen-added nitrile butadiene rubber which does not have the reactivity with the carbodiimide group, and is used for maintaining the airtightness of each part, in a compressor for a refrigerator which uses the fluorinated hydrocarbon group refrigerant and the ester group synthetic lubricating oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor head gasket or muffler gasket for a refrigerator, and more particularly to a fluorohydrocarbon refrigerant (HF).
A cylinder head gasket or a muffler gasket used for maintaining airtightness of each part in a compressor of a refrigerator using C) and a refrigerator oil made of an ester synthetic lubricating oil, and using asbestos fibers. However, the present invention relates to a compressor head gasket or muffler gasket for a refrigerator, which exhibits excellent strength, sealability and resistance to the refrigerant and the refrigerator oil.

[0002]

2. Description of the Related Art Conventionally, in a refrigerating cycle such as a refrigerator or an air conditioner, dichlorodifluoromethane (CF ₂ Cl ₂ ) having no polar group has been mainly used as a refrigerant.
Mineral oil was mainly used as a refrigerating machine oil, but due to the recent environmental problems of the earth, the dichlorodifluoromethane containing a chlorine atom cannot be used, and 1,1,1,2-tetrafluoro is used in place of this. Ethane (HFC134
Only fluorohydrocarbon-based refrigerants (HFC) containing no chlorine atom, represented by a), are becoming available.

However, the chlorine-free fluorohydrocarbon-based refrigerant represented by 1,1,1,2-tetrafluoroethane has a polar group and therefore has a compatibility with mineral oil and the like. It lacks, and when this is used, conventional mineral oil cannot be used as compressor refrigeration oil.

Therefore, in order to solve this problem, it has been proposed to use, as a refrigerating machine oil, an ester-based synthetic lubricating oil having a polar group in its constituent molecule.

On the other hand, gaskets used for compressors of refrigerators are typically represented by asbestos as a base fiber, acrylonitrile-butadiene rubber (NBR) or chloroprene (CR) as a binder. A rubber material, a vulcanizing agent for vulcanizing this rubber material, and a filler were used to provide sealing properties, strength, and resistance to refrigerants and refrigerating machine oil, but in recent years, asbestos has a negative effect on the human body. Has been pointed out, and it has become difficult to obtain and handle it, and it is becoming impossible to use it.

[0006] For this reason, research has been actively conducted to manufacture an asbestos sheet substitute using a fiber base material that replaces asbestos. For example, as a substitute for asbestos, glass fiber, rock wool, ceramic fiber,
It has been proposed to use inorganic fibers such as carbon fibers, organic fibers such as aramid, polyester, phenol, and cellulose, and pulp, and a rubber material as a binder, and a sheet formed with a vulcanizing agent and a filler for this rubber material It is attracting attention as an asbestos sheet.

[0007]

However, unlike the conventionally used dichlorodifluoromethane, the fluorohydrocarbon-based refrigerant has a polarity, and therefore has a corrosiveness with respect to an organic material, particularly an ability to dissolve the organic material. HFC134a, which is expensive and has a smaller molecular size than dichlorodifluoromethane, has a problem that it has a high ability to penetrate and permeate a gasket.

On the other hand, also in the gasket, the above-mentioned inorganic and organic fibers used in place of asbestos have a larger fiber diameter than asbestos, which is a disadvantageous shape for a dense structure. It is impossible to obtain a sufficiently satisfactory sealing property for use as a gasket of the compressor.

That is, typically, a conventional refrigerant / refrigerant oil combination such as dichlorodifluoromethane / mineral oil system is used.
If the combination of HFC134a / ester oil is used as it is, the conventional non-asbestos sheet gasket will corrode the binder part such as NBR that is usually used, resulting in the durability required for the refrigerator gasket. Poor, and the sealing property is also insufficient, further sulfur and peroxide which are vulcanizing agents of the end reaction contained in the non-asbestos sheet are eluted in the refrigerating machine oil,
Oxidative deterioration of refrigerating machine oil, resulting in reduced lubricity,
In addition, in some cases, the fatty acid produced by the decomposition may corrode the metal part, or may generate a precipitate, which may significantly impair the performance of the compressor.

The present invention solves the above-mentioned drawbacks of the prior art, and uses a fluorohydrocarbon-based refrigerant and a refrigerating machine oil used together with the refrigerant, which is an ester-based synthetic lubricating oil, without using asbestos. Used in the compressor of the machine, it keeps the airtightness of each part sufficiently, and also has excellent strength and durability,
It was made for the purpose of providing a head gasket or muffler gasket for a compressor of a refrigerator that does not generate a precipitate.

[0011]

In order to achieve the above object, the structure of a compressor compressor head gasket or muffler gasket of a refrigerator adopted by the present invention is at least an inorganic filler other than asbestos and a polycarbodiimide resin. ,
Refrigeration comprising a fiber component of organic fiber or inorganic fiber and hydrogenated nitrile butadiene rubber having no reactivity with a carbodiimide group, using a fluorohydrocarbon refrigerant and a refrigerating machine oil of an ester synthetic lubricating oil The compressor of the machine is characterized by being used for maintaining airtightness of each part and ensuring durability.

The present invention will be described in detail below.

First, the inorganic filler used in the sheet material of the present invention is not particularly limited as long as it is an inorganic filler other than asbestos. Specifically, fibers such as glass fiber, and sericite, kaolin, clay, talc,
Ceviolite, barium sulfate, mica, vermiculite, calcium carbonate, silica, wollastonite, magnesium sulfate, potassium titanate, carbon black and other powders, apples or whiskers, or an appropriate mixture thereof Can be illustrated.

The polycarbodiimide resin used in the present invention is a known one, or can be produced in the same manner as a known one. {US Pat. No. 2,941,956 Book; Japanese Patent Publication No. 47-3327
No. 9 publication; J. Org. Chem. , 28 , 2069-
2075 (1963) Chemical Review
l981, vol. 81l. No. 4,619-62
1 etc.}, for example, in the presence of a carbodiimidization catalyst,
It can be easily produced by a condensation reaction involving decarbonization of organic diisocyanate.

The organic diisocyanate used for producing the polycarbodiimide resin may be of any type such as aliphatic type, alicyclic type, aromatic type and aromatic-aliphatic type. Used alone, or
You may use it as a copolymer combining 2 or more types.

Thus, the polycarbodiimide resin used in the present invention has the following formula -RNN = C = N- (wherein R represents an organic diisocyanate residue).
A homopolymer or copolymer composed of at least one repeating unit represented by

As R in the above formula, which is an organic diisocyanate residue, an aromatic diisocyanate residue is particularly preferable (here, the organic diisocyanate residue is obtained by removing two isocyanate groups (NCO) from the organic diisocyanate molecule). I say the rest). Specific examples of such an organic diisocyanate include formula (1),

Embedded image Or formula (2),

Embedded image Or formula (3),

Embedded image What is represented by can be illustrated.

Explaining the substituents in the above formula, R
₁ , R ₂ and R ₃ are a lower alkyl group represented by a methyl group, an ethyl group, a propyl group, a butyl group or the like or a corresponding lower alkoxy group, R ₄ and R ₅ are hydrogen atoms, and R _{1 to} R ₃ The same lower alkyl group or lower alkoxy group and X represent an oxygen atom or a methylene group, respectively.

Specifically, as the organic diisocyanate represented by the above formula (1), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Tolylene diisocyanate such as a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, etc., and an organic diisocyanate are represented by the above formula (2). Examples thereof include o-tolidine diisocyanate, and further, those in which the organic diisocyanate is represented by the above formula (3) include 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyl ether diisocyanate and 3,3-. Dimethyl-4,4'-diphenyl ether diisocyanate and the like can be mentioned respectively,
These diisocyanates can be used alone or as a mixture of two or more kinds.

The reaction for converting the above organic diisocyanate into a polycarbodiimide resin is carried out in the presence of a carbodiimidization catalyst. Examples of the carbodiimidization catalyst include 3-methyl-1-phenyl-2-phosphorene-1- Phosphorene oxides such as oxides can be mentioned.

The polycarbodiimide resin used in the present invention may be in the form of pulp or powder. For example, polycarbodiimide pulp may be prepared from the organic diisocyanate represented by the above formulas (1) to (3). In the production, first, an organic diisocyanate is subjected to a polymerization reaction using an alicyclic ether as a solvent in the presence of a carbodiimidization catalyst to obtain a dope of a polycarbodiimide resin.

The above-mentioned organic diisocyanate is reacted in an alicyclic ether, and this alicyclic ether is preferably liquid at room temperature and has 2 or less ether bonds in the molecule. is there. In particular,
Tetrahydrofuran, dioxane, tetrahydropyran or a mixed solvent thereof can be mentioned as an example, and among them, tetrahydrofuran is preferable.

The dope thus obtained is discharged into a pulp form by discharging it with a coagulating liquid, for example, through a nozzle and bringing them into contact with each other, as described in JP-A-5-195483. To obtain the polycarbodiimide resin.

The powdery polycarbodiimide resin used in the present invention is, for example, a method of spray-drying a polycarbodiimide resin solution described in JP-A-5-239223, or JP-A-51-61599. It can be obtained by a method of collecting a powdery product which is precipitated by reacting in a general solvent described in 1).

In the present invention, in addition to the above components, organic fibers or pulp or inorganic fibers thereof are added. Specifically, as the organic fibers (pulp), aramid type, polyester type, cellulose type, polyacrylonitrile type, Phenolic fibers (pulp) can be mentioned, and particularly preferred is aramid fiber (pulp),
Examples of the inorganic fiber include glass fiber, carbon fiber, rock wool, ceramic wool and the like.

In the present invention, in addition to the above components, a rubber material which does not react with the carbodiimide group of the polycarbodiimide resin is used. However, it is preferable that the rubber material does not contain a vulcanizing agent. Can include hydrogenated nitrile butadiene rubber (hydrogenated NBR).

The proportion of each component described above may be appropriately determined depending on the purpose of use or the conditions. For example, an inorganic filler other than asbestos 40 to 70% by weight polycarbodiimide resin 1 to 30% by weight fiber component 3 to 30% by weight Hydrogenated nitrile butadiene rubber 5 to 30% by weight can be mentioned.

On the other hand, the gasket of the present invention characterized as described above is at least reactive with an inorganic filler other than asbestos, a polycarbodiimide resin, a fiber component of organic fibers or inorganic fibers, and a carbodiimide group. It can be obtained by mixing a composition composed of a hydrogenated nitrile butadiene rubber that does not exist, forming a sheet, and then heat-pressing at a temperature equal to or higher than the softening point of the polycarbodiimide resin.

The sheet-like material can be molded by the above composition by a press molding method or a roll molding method, and the heating temperature can be, for example, a value of 150 ° C. or higher and 300 ° C. or lower.

The features of the present invention are, therefore, a hydrogenated nitrile butadiene rubber excellent in resistance to a refrigerating machine oil due to a fluorohydrocarbon refrigerant and an ester synthetic lubricating oil used for the refrigerant, and That is, a thermosetting polycarbodiimide resin was used.

Therefore, by manufacturing the gasket of the present invention as described above, 1) the gasket can be endowed with resistance to the fluorohydrocarbon refrigerant and the refrigerating machine oil used for the refrigerant. 2) Since it is formed above the softening point of the polycarbodiimide resin, the polycarbodiimide resin fills in the voids between the fibers, which is a problem in conventional products, and improves the sealing property. 3) Since it is formed above the softening point of the polycarbodiimide resin, the binding strength between the fiber component and the inorganic filler is increased by the polycarbodiimide resin, and sufficient strength can be obtained without using a vulcanizing agent. That is, the deterioration of the refrigerator oil is reduced,
Metal corrosion is also eliminated, and the life of the compressor can be extended.

[0032]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 (1) Production of polycarbodiimide pulp After a Dimroth condenser, a thermometer and a mechanical stirrer were attached to a 4-necked flask, 4000 ml of tetrahydrofuran was added from the raw material charging port. Next is the raw material MDI
(4,4'-diphenylmethane diisocyanate) 65
0 g was added, and 0.2% by weight of 3-methyl-1-phenyl-2-phosphorene-1 based on the raw material isocyanate.
-Oxide was added and the reaction was carried out under reflux for 7 hours to obtain a dope of polycarbodiimide resin. At this time, the monomer concentration was 15.5% and the NCO% was 1.0.

The dope produced as described above was charged into an autoclave, one of which was connected to a nozzle and the other was connected to a compressor, and the dope was discharged by back pressure. A two-fluid nozzle (manufactured by Spraying System Co., Ltd.) was used as the nozzle. Using this apparatus, the dope discharge rate was adjusted to 10 ml / min and the coagulant discharge rate was adjusted to 1010 ml / min by back pressure, and the mixture was discharged onto a coagulation bath to form pulp. This was filtered and dried to obtain the desired pulp.

(2) Production of Gasket Polycarbodiimide resin pulp 15% by weight Rubber material (hydrogenated NBR latex [solid content]) 23% by weight Aramid pulp (fiber component) 10% by weight Inorganic filler 52% by weight Composition of the above composition The materials were mixed and made into a sheet to form a sheet. Next, this sheet-like material is heated at 200 ° C. and 200 kg /
It was heated and pressed at 10 cm ² for 10 minutes to obtain a gasket having a thickness of 0.5 mm.

Example 2 (1) Preparation of polycarbodiimide powder 675 g of MDI (4,4'-diphenylmethane diisocyanate) and 71.4 g of phenyl isocyanate were mixed with 2458 g of tetrachloroethylene to prepare a carbodiimidization catalyst (3-methyl-1-phenyl-). 2-phospholen-1-oxide) (1.5 g) was reacted at 120 ° C. for 4 hours to obtain a pale yellow and transparent polycarbodiimide solution (resin concentration 20%). This solution was cooled to 40 ° C. for 12 hours to obtain a slurry polycarbodiimide having a viscosity of 270 cp. The slurry polycarbodiimide was dried at a temperature of 60 ° C., an air pressure of 2 kg / cm ² , and a slurry supply amount of 1 l.
Spray drying under the condition of / h gave a pale yellow powder.

(2) Manufacture of gasket Polycarbodiimide resin powder 15% by weight Rubber material (hydrogenated NBR latex [solid content]) 20% by weight Aramid pulp (fiber component) 10% by weight Inorganic filler 55% by weight Composition of the above composition The materials were mixed and made into a sheet to form a sheet. Next, this sheet-like material is heated at 180 ° C. and 200 kg /
It was heated and pressed at 10 cm ² for 10 minutes to obtain a gasket having a thickness of 0.5 mm.

Comparative Examples 1 to 3 As a gasket, a sheet using commercially available NBR / asbestos (Comparative Example 1), a non-asbestos sheet using acrylic rubber / aramid fiber (Comparative Example 2) and NBR
A non-asbestos sheet (Comparative Example 3) made of cellulose fiber was prepared.

Comparative Test The gaskets produced in Examples 1 and 2, the sheet of Comparative Example 1 and the non-asbestos sheets of Comparative Examples 2 and 3 were punched into predetermined shapes and set as gaskets in a compressor of a refrigerator, The actual operation was performed to evaluate the presence or absence of damage to the gasket and the oil deterioration (total acid value / presence of precipitates). The results are shown in Table 1 below.

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 7/02 C08L 79/00 LQZ C09K 3/10 NZ // C08G 18/02 NDK B29K 9: 00 503: 04 (72) Inventor Takahiko Ito 1-18-1 Nishiaraicho, Adachi-ku, Tokyo Nisshin Spinning Co., Ltd. Tokyo Research Center (72) Inventor Kenichi Sekioka 2-1-1 Kano, Higashiosaka-shi, Osaka Japan Gasket Co., Ltd. (72) Inventor I ▲ Sao ▼ Shizuo Osaka Prefecture Higashi-Osaka City 2-1-1 Kano Japan Gasket Co. Ltd. (72) Inventor Kenichi Horinouchi 2-1-1 Kano Higashi-Osaka City, Osaka Prefecture Issue Japan Gasket Co., Ltd. (72) Inventor Yuji Mori 3-22 Takaidahondori, Higashi-Osaka City, Osaka Prefecture Matsushita Cold Machinery Co., Ltd.

Claims (1)

[Claims] 1. At least an inorganic filler other than asbestos, a polycarbodiimide resin, a fiber component made of an organic fiber or an inorganic fiber, and a hydrogenated nitrile butadiene rubber having no reactivity with a carbodiimide group,
A compressor head for a refrigerator, which is used for maintaining airtightness of each part in a compressor for a refrigerator using a fluorohydrocarbon refrigerant and a refrigerator oil made of an ester synthetic lubricating oil. Gasket or muffler gasket.