JP2946185B2 - Joint sheet and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to replace a specific chlorofluorocarbon, which is subject to use restrictions due to the problem of depletion of the ozone layer, in a joint sheet used as a gasket at a joint portion of a pipe or the like in a refrigerator or the like. The present invention relates to a joint sheet useful for a refrigeration system using an alternative fluorocarbon and an ester-based lubricating oil used therewith.

[0002]

2. Description of the Related Art Asbestos joint sheets (abbreviated as A.J / S) made of asbestos fibers have been widely used as joint sheets. Because it has a unique shape and excellent heat resistance, asbestos fibers are used to manufacture asbestos joint sheets using those characteristics and process the sheets into stamped gaskets to produce water, oil, air, It has been used as a gasket for piping and equipment for water vapor. However, asbestos fibers used for the asbestos joint sheet are natural products, and there is a concern that resources may be depleted, and use of asbestos fibers is being restricted worldwide due to environmental health problems. Therefore, recently, asbestos fiber is not used at all,
A joint sheet is used in which an inorganic fiber and / or an organic fiber other than the asbestos fiber and / or a filler is blended with rubber as a binder. This joint sheet is an asbestos-free joint sheet or a non-asbestos joint sheet (hereinafter referred to as NA-J).
Abbreviated as / S. ) And is widely used.

[0003] Further, NA · J / S is used for various pipes and equipments. In particular, NA · J / S used for refrigerators and air conditioner compressors includes a refrigerant, Freon, and refrigerating machine oil. In order to seal the mixed system, a higher sealing property is required as compared with NA · J / S used for piping and equipment for water, oil, air, steam, and the like. Further, since the NA · J / S for the refrigerating apparatus does not blow out even if the sheet is used while being vibrated while the refrigerating machine is operating, it is of course necessary to initially use the tension during use. Great strength is also required. Therefore, especially NA ・ J for refrigeration equipment
As a rubber of / S, acrylonitrile butadiene rubber having high polarity, high vulcanization degree and good oil resistance (hereinafter, referred to as
Abbreviated as NBR. ) Is the mainstream. The inventors of the present invention have also conducted intensive studies on NA · J / S for refrigeration equipment, and by adjusting the ratio of NBR, fibrillated fibers, vulcanizing agents, and active fine particles such as carbon black. It has been found that NA · J / S with good characteristics can be obtained.

[0004] NA · J / S using NBR is an NBR (or powder NB) obtained by swelling a fiber material, a filler (carbon black or the like), a rubber chemical such as a vulcanizing agent in a solvent.
R or NBR latex with a solvent) and kneaded well with a Henschel mixer or the like, and put the kneaded material between a pair of rolls consisting of a hot roll (about 150 ° C) and a cold roll (about 20 ° C). Then, the NBR is vulcanized together with the evaporation of the solvent while the kneading material is laminated on the hot roll side, and finally the sheet material laminated on the hot roll side is peeled off.

[0005]

However, in the conventional method of manufacturing NA / J / S, the vulcanization of NBR is carried out by a heat roll process, in which a heat gradient occurs in the sheet thickness direction. In some cases, blooming occurs and the surface properties of the sheet deteriorate, or the vulcanization becomes uneven or the degree of vulcanization is insufficient, so that sufficient mechanical strength or oil resistance may not be obtained. .

On the other hand, in recent years, due to the problem of depletion of the ozone layer, specific fluorocarbons have been subject to use restrictions worldwide, and alternative fluorocarbons have been developed and used in place of these fluorocarbons. Along with this, ester lubricating oil has been used instead of conventional mineral oil for refrigeration oil, but this ester lubricating oil has a stronger effect of swelling rubber than mineral oil, and NBR which is excellent in oil resistance for a long time. It swells due to extensive contact. The rubber chemicals in the NA / J / S are eluted by the swelling, and the eluted components flow through the piping of the refrigerating device together with the ester-based lubricating oil. A malfunction occurs in the refrigeration system. Since this swelling depends on the degree of vulcanization, when the degree of vulcanization is insufficient as described above, it becomes more remarkable.

An object of the present invention is to provide a refrigeration system using an alternative chlorofluorocarbon and an ester-based lubricating oil, which does not have the above-mentioned disadvantages and has excellent mechanical strength, and is suitable as a gasket for piping of the refrigeration system. NA / J / S.

[0008] The object of the present invention is to provide a fiber material, rubber,
Acrylic nitrile butadiene rubber of 15 to 30% by weight of the total joint sheet, carbon black of 30 to 300% by weight based on the weight of the acrylonitrile butadiene rubber, weight of the acrylonitrile butadiene rubber A sheet-like vulcanizate containing 1.0 to 5.0 % by weight of sulfur or an organic sulfur-containing compound as an essential component in terms of the amount of sulfur in 100 to 210 ° C.
Joint sheet (NA / J / A) characterized by being heat-treated in an autoclave at a temperature for 60 to 420 minutes.
S). A similar purpose is to put a kneaded material containing a fiber material, acrylonitrile butadiene rubber, carbon black, sulfur or an organic sulfur-containing compound between a hot roll and a cold roll, and roll by heating and vulcanize the sheet. after forming the object, the sheet-like vulcanized product 100 to 210
A heat treatment in an autoclave at a temperature of 60 ° C. for 60 to 420 minutes.
This is also achieved by the manufacturing method of S).

The rubber component of NA · J / S according to the present invention comprises:
Use NBR with good oil resistance. NBR has good compatibility with sulfur and organic sulfur compounds as vulcanizing agents and is easy to vulcanize, so that the degree of vulcanization can be increased. If the amount of NBR used is lower than 15% by weight of the total weight of the components constituting NA · J / S, voids are formed in the molded product, whereby the sealing properties are reduced and the mechanical properties such as tensile strength are deteriorated. On the other hand, NBR
If the amount used exceeds 30% by weight of the total weight of components, mechanical properties such as tensile strength are rather deteriorated. Moreover, when it is made into a kneaded material, it is too soft, resulting in poor processability. This N
A particularly preferred range for BR is 17-25% by weight.

For vulcanizing the above-mentioned NBR, a vulcanizing agent comprising sulfur or an organic sulfur-containing compound is converted into NBR1 in terms of sulfur amount.
1.0 to 5.0 parts by weight, preferably 1.0 to 3.0 parts by weight, is added to 00 parts by weight. If the compounding amount is less than 1.0 part by weight, vulcanization does not proceed, and if the compounding amount is more than 5.0 parts by weight, the surface of the sheet blooms during molding, and sulfur is mixed into the ester-based lubricating oil during use. To erode the copper tubing. Examples of the organic sulfur-containing compound include tetramethylthiuram disulfide (Noxeller TT manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) and 4-4′-dithiodimorpholine (Valnoc manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
R), 2- (4'-morpholinodithio) benzothiazole (NOCSELA MD manufactured by Ouchi Shinko Chemical Co., Ltd.)
B), dipentamethylenethiuram tetrasulfide (Noxeller TRA manufactured by Ouchi Shinko Chemical Co., Ltd.) and the like, but are not limited thereto, and may be any organic sulfur-containing compound capable of vulcanizing NBR.

In addition to the above sulfur and organic sulfur-containing compounds, vulcanization aids such as zinc oxide and magnesium oxide, aldehyde ammonia type, thiuram type, dithiocarbamate type, sulfenamide type, thiazole type, guanidine type, thiourea type , Vulcanization accelerators such as xanthate and aldehydeamine can be used in combination.

Further, as the rubber chemicals other than the above-mentioned vulcanization system, an appropriate amount of an antioxidant, a surfactant, an anti-scorch agent, a plasticizer, a coloring agent and the like can be used. However, the amount of these compounds is preferably minimized because it is considered that the amount of these compounds becomes an extract from the sheet and accelerates the deterioration of the ester-based lubricating oil.

The NA.J / S according to the present invention contains carbon black as an essential component as a filler, and the amount of the component is 30 to 300 parts by weight, particularly 30 to 150 parts by weight based on 100 parts by weight of NBR. Is preferred. Carbon black forms a carbon gel when kneaded with NBR, and enhances the mechanical strength of the molded product. Further, it becomes a cross-linking point of NBR, and has the same effect as an increase in the degree of vulcanization. Therefore, when carbon black is added in an amount of 300 parts by weight or more based on 100 parts by weight of NBR, the workability of the kneaded material is reduced, and the brittleness of the molded product is reduced. 3
Addition of 0 parts or less gives the same result as the decrease in the degree of vulcanization of NBR as described above, and produces bad results such as increased elution into lubricating oil and a decrease in mechanical strength.

As fillers other than carbon black,
Clay, talc, barium sulfate, sodium bicarbonate, graphite, kaolinite, sericite, calcined clay,
Wollastonite or the like can be added alone or in an appropriate amount in combination of two or more.

The NA.J / S according to the present invention contains an appropriate amount of inorganic fibers and / or organic fibers other than asbestos. By blending the fibers, the mechanical strength of NA · J / S increases. Suitable fibers include aromatic polyamide fibers,
Cellulose pulp such as polyethylene fiber, acrylic fiber, nylon fiber, bamboo pulp, softwood pulp, phenol fiber, aromatic polyamide fiber (chopped fiber)
And inorganic fibers such as rock wool, carbon fiber, glass fiber and sepiolite. These organic fibers and inorganic fibers are used alone or in combination. Among the organic fibers, aromatic polyamide fibers, polyethylene fibers, acrylic fibers, and nylon fibers, which are synthetic fibers, are preferably formed by fibrillation because the tensile strength of NA · J / S is improved. The organic fiber and the inorganic fiber may be fibers used in conventional NA · J / S. The aromatic polyamide fiber, polyethylene fiber, acrylic fiber, nylon fiber and the like are added at a ratio of 10 to 40% by weight based on the total weight of NA · J / S. 4
It is not necessary to add 0% by weight or more, and addition of 40% by weight or more is rather undesirable because it makes it difficult to obtain a uniform composition.

The NA.J / S according to the present invention is prepared by first kneading the above-mentioned substances sufficiently using a suitable solvent with a Henshal mixer or the like, based on a conventional production method, and then heating the kneaded material with a heat-roller. Between the pair of rolls (about 150 ° C.) and cold rolls (about 20 ° C.)
While vulcanizing R, a sheet is formed. Subsequently, NA · J / S according to the present invention is obtained by heat-treating the sheet in an autoclave. The heat treatment in an autoclave is preferably performed at a temperature between 100 and 210 ° C. for 60 minutes or more, more preferably at 130 to 180 ° C. for 60 to 240 minutes.

When the amount of extraction of the mixture of NA / J / S obtained by the above-mentioned method and the alternative fluorocarbon and the ester-based lubricating oil was measured, the amount of the extract was determined as shown in FIG. It was confirmed that it decreased with the increase. Further, it was found that the extraction amount is practically preferably 0.5% or less, and it takes about 60 minutes as a processing time to satisfy the value. At the same time, when the total acid value indicating the state of deterioration of the ester-based lubricating oil was examined, it was confirmed that the acid value decreased with the time of the autoclave treatment, as shown in FIG.
H / g], it was found that a processing time of about 60 minutes was required. The heating temperature and the treatment time in the autoclave treatment are in an inverse relationship, and the higher the heating temperature and the longer the treatment time, the more the vulcanization proceeds, but when organic fibers are mixed,
The organic fibers may be deteriorated. On the other hand, if the heating temperature is low and the treatment time is short, vulcanization may not proceed. Therefore, when carrying out the process, the optimum conditions are determined while keeping these factors in mind.

This autoclave heat treatment is a treatment for vulcanizing an unreacted part of the vulcanization by the hot roll. At that time, by performing the treatment for a relatively long time, the vulcanization proceeds uniformly and sufficiently in the thickness direction of the sheet. Further, there is also obtained a secondary effect that the sheet surface is washed by steam in the autoclave container to remove unreacted sulfur and various compounds in the sheet and on the sheet surface. Therefore, according to the production method of the present invention, the unvulcanized components that are eluted are reduced, and the unvulcanized components and other compounds are also purified even if they ooze on the sheet surface. No matter is mixed into the ester lubricating oil to deteriorate the lubricating oil or corrode the copper pipe. Furthermore, as a result of an increase in the degree of vulcanization, the mechanical strength characteristics of NA · J / S also show good values.

[0019]

EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited by this.

(Example 1)
After measuring a predetermined amount of NBR thinned to 2 mm,
Swelled in 300 parts by weight of toluene, Henschel with fiber materials, carbon black, fillers other than carbon black, vulcanizing agents (sulfur), vulcanization accelerators, and other rubber chemicals in the proportions shown in A of Table 1. The mixture was kneaded with a mixer for 80 minutes. The obtained kneading material is placed on a hot roll at 150 ° C., 2
Pressure vulcanization molding was performed using a cold roll calender roll at 0 ° C. to obtain a 1.5 mm thick sheet. The sheet was post-treated at 150 ° C. for 60 minutes by an autoclave to obtain NA · J / S.

[0021]

[Table 1]

Example 2 A sheet having the composition shown in Table 1A and produced by the same method as in Example 1 was treated in an autoclave at 150 ° C. for 90 minutes to obtain a NA. J / S was obtained.

(Example 3) A sheet having the composition shown in Table 1A and produced in the same manner as in Example 1 was treated in an autoclave at 150 ° C for 120 minutes, and subjected to NA · J / S was obtained.

(Comparative Example 1) A sheet having the composition shown in Table 1A and produced by the same method as in Example 1 was converted into NA · J / S without autoclaving. .

(Comparative Example 2) A sheet having the composition shown in Table 1A and produced in the same manner as in Example 1 was post-treated in an autoclave at 150 ° C for 30 minutes, and subjected to NA -J / S was obtained.

(Comparative Example 3) A sheet material having the composition shown in Table 1B and produced by the same method as in Example 1 was post-treated at 150 ° C for 90 minutes by an autoclave to obtain a NA. -J / S was obtained.

Table 2 shows the physical properties of each NA · J / S obtained in Examples 1 to 3 and Comparative Examples 1 to 3.

[0028]

[Table 2]

In Table 2, the tensile strength, compression ratio, restoration ratio and stress relaxation ratio of NA · J / S are based on JIS R345.
3 was measured. The sealability is sandwiched NA · J / S punched in a ring shape with a flange, N ₂ gas pressure of 15
The amount of leakage per hour when kgf / cm ² was loaded was determined by an underwater replacement method. In addition, in order to examine the CFC resistance and the refrigerator oil resistance, an alternative CFC, an ester-based lubricating oil, and NA · J / S were placed in a closed container, and subjected to a treatment at 150 ° C. for 22 hours. The strength reduction rate was measured. Further, the extraction amount of the eluted material was measured from the weight change of NA · J / S before and after the treatment. The measurement of the deterioration state of the lubricating oil is performed by using alternative Freon, ester-based lubricating oil, and NA ・ J / S
Was placed in a closed container and treated at 150 ° C. for 30 days, after which the ester-based lubricating oil was taken out and its total acid value was measured. The total acid value was measured according to JIS K2501. The smaller the value of the total acid value, the better. Usually, it can be used if it is about 0.10 or less, and preferably about 0.05 or less. The copper plate corrosion is a measure of the amount of unreacted sulfur remaining in NA · J / S, and was visually observed.

From Table 2, it can be seen that the NA of the present invention of Examples 1 to 3 was
・ J / S is the tensile strength, compression ratio, restoration ratio,
The mechanical strength characteristics such as the stress relaxation rate and the sealing property are equal to or higher than those of NA · J / S of the comparative example, and the same handling as the conventional one is possible. However, NA · J / S of the present invention is:
Since the rate of decrease in tensile strength, the amount of extraction, and the value of the total acid value of the ester-based lubricating oil are also lower than the NA · J / S of the comparative example, the resistance to the mixed system of the alternative fluorocarbon and the ester-based lubricating oil is low. It turns out that it is excellent. On the other hand, as in Comparative Example 1, in the case of NA · J / S in which no autoclave treatment is performed after sheet production and only a crosslinking reaction is performed by a hot roll at the time of sheet production, the sulfur is not sufficiently reacted, so that rubber is not sufficiently reacted. Extraction, the total acid value of the lubricating oil became worse, and copper plate corrosion was also confirmed. In Comparative Example 2, since the autoclave treatment time after sheet making was shorter than the range of the present invention, both the rubber extraction and the total acid value of the lubricating oil showed bad values. In Comparative Example 3, although the autoclave treatment was performed within the range specified in the present invention, the resistance to the mixed system of the alternative fluorocarbon and the ester-based lubricating oil was improved, but the sulfur amount was within the range of the present invention. Due to the large amount, the total acid value was poor and copper plate corrosion was confirmed. Also, the sealing properties were poor.

[0031]

As described above, according to the present invention, by performing the autoclave treatment, the unvulcanized components in NA · J / S which are eluted materials are reduced, and the unvulcanized components and Because other compounds are purified even if they ooze out on the sheet surface, these elutes can be mixed into the ester-based lubricating oil to deteriorate the ester-based lubricating oil or corrode the copper pipe. Absent. Further, as the degree of vulcanization increases, N
The mechanical strength characteristics of A.J / S also show good values.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the autoclave treatment time of NA · J / S of the present invention and the amount of extraction with an ester-based lubricating oil.

FIG. 2 is a graph showing the relationship between the autoclave treatment time of NA · J / S of the present invention and the total acid value of an ester-based lubricating oil in which the sheet is immersed.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09K 3/10 C09K 3/10 Z (72) Inventor Toru Segawa 4-1000-4G Matsumicho, Kanagawa-ku, Yokohama-shi, Kanagawa-ken (72) Inventor Takuya Hirokawa 4-1000-3L, Matsumi-cho, Kanagawa-ku, Yokohama-shi, Kanagawa (56) References JP-A-64-63135 (JP, A) JP-A-3-56772 (JP, A) JP-A-5-179230 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 21/00 C08K 3/04 C08K 3/06 C08K 7/02 C09K 3/10

Claims (2)

(57) [Claims] 1. A composition comprising a fibrous material, rubber, a rubber chemical, a filler, etc., and having a weight of 15% of the total joint sheet weight.
Acrylonitrile butadiene rubber in an amount of 30 to 30% by weight based on the weight of the acrylonitrile butadiene rubber.
0 to 100% by weight of a sheet-like vulcanizate containing 1.0 to 5.0 % by weight of sulfur or an organic sulfur-containing compound as an essential component in terms of sulfur based on 0% by weight of carbon black and the acrylonitrile butadiene rubber. At the temperature of 60-420 minutes
Joint sheet, characterized by comprising a heat treatment at between autoclave. 2. A kneaded product containing a fibrous material, acrylonitrile butadiene rubber, carbon black, sulfur or an organic sulfur-containing compound is charged between a hot roll and a cold roll, and heated and rolled to form a sheet-like vulcanized sheet. After molding into a product, the sheet-like vulcanizate is heated at a temperature of 100 to 210 ° C for 60 to 420
A method for producing a joint sheet, wherein the joint sheet is heat-treated in an autoclave for one minute.