JP3329429B2 - Sheet-shaped composite materials and gaskets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sheet-like composite material suitable as a gasket material or a packing material. More specifically, gasket materials for cylinder heads of internal combustion engines, gasket materials used to seal various joints around oil and water around internal combustion engines, packing materials used for valves, pumps, pipe joints, etc. It relates to a suitable sheet-like composite material. The present invention also relates to a gasket using the sheet-like composite material.

[0002]

2. Description of the Related Art Conventional gasket materials include JIS-R
An asbestos joint sheet or the like mainly using asbestos has been used as shown in -3453, JIS-7S-40 and the like. However, asbestos has been shown to be harmful to the human body and its use is problematic. Therefore, as a gasket material not using asbestos, organic and inorganic fillers are kneaded with an organic binder such as rubber, for example, as shown in Nichias Technical Bulletin, No. 241, March 1986, to form a sheet. Joint sheet, JP-A-2-38760, JP-A-3-22
As shown in Japanese Patent No. 9069 and the like, for example, a metal gasket material in which a rubber layer is coated on the surface of a metal plate such as a stainless steel plate or a normal steel plate is used.

[0003] In recent years, as a gasket material with further improved heat resistance and sealing properties, a metal gasket material having an expanded graphite layer provided on the surface of a reinforcing core has been receiving attention. For example, according to Japanese Patent Publication No. 5-63670, after cleaning and degreasing the surface of a steel sheet, a phenolic thermosetting adhesive is applied to the surface, and an expanded graphite powder is placed on the upper surface, and 10 to 150 μm is applied by a compression roll. A method of manufacturing a metal gasket has been proposed in which a sheet-like material is adhered by pressing to a thickness of 3 mm and then heated in a heating furnace at a curing temperature of a thermosetting adhesive for several minutes. However, a joint sheet obtained by kneading an organic or inorganic filler with an organic binder such as rubber to form a sheet has a low heat resistance temperature and a weak tensile strength of about 14.7 MPa (150 kgf / cm ² ). It is difficult to use in high temperature and high load application parts.

[0004] A metal gasket material in which a reinforcing steel plate and a rubber material or expanded graphite are bonded together uses a thermosetting resin such as a phenol resin or an epoxy resin as an adhesive.
However, when the adhesive used when bonding the rubber material as the sealing material and the expanded graphite to the surface of the reinforcing core material is an epoxy resin, the heat resistance is not sufficient, and when the ordinary phenol resin is used, the adhesive is hardened. Since condensed water is sometimes generated, there is a problem in that the adhesiveness is reduced, and the sealing material of the gasket material to be produced is easily swelled and the sealing performance is reduced.

[0005]

The present invention solves the above-mentioned problems. The first aspect of the present invention provides a sheet-like composite material which is excellent in heat resistance and sealing properties and is used for a high-strength gasket, packing or the like. The invention according to claim 2 provides a sheet-like composite material having particularly excellent heat resistance and sealing properties in addition to the invention according to claim 1. The third aspect of the present invention is to provide a gasket which is excellent in heat resistance and sealability and has high strength.

[0006]

According to the present invention, the reinforcing core material and the sealing material are represented by the general formula (A) as a resin containing a dihydrobenzoxazine ring in the molecule.

Embedded image (Wherein the hydrogen bonded to the aromatic ring is
May be substituted with a substituent except for one of the G-positions) and
General formula (B)

Embedded image (Wherein R ¹ is a hydrocarbon group, and water bonded to an aromatic ring is
May be substituted with a substituent).
Is 4/1 to 1 in the molar ratio of general formula (A) / general formula (B).
The present invention relates to a sheet-like composite material formed by laminating and bonding one or both surface layers so as to be a sealing material using a resin containing 1/9 as an adhesive. The present invention also relates to a sheet-like composite material in which the sealing material is an expanded graphite sheet.

[0007] The present invention also relates to a gasket obtained by processing each of the sheet-like composite materials.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The reinforcing core material used in the present invention is not particularly limited. For example, a metal plate such as a stainless steel plate and a normal steel plate, a metal mesh such as a stainless steel and a normal steel,
Use a sheet-like material with a higher strength than the sealing material, such as organic fiber cloth such as cellulose, asbestos, glass, carbon, inorganic fiber cloth such as ceramic, and various organic or inorganic films. Can be. The reinforcing core material to be used can be appropriately selected depending on the use of the sheet-like composite material.

The sealing material used in the present invention is not particularly limited as long as it has a sealing property.
Sheets of rubber materials such as nitrile rubber and silicone rubber, fillers such as granules and fibers, joint sheets made of organic binders, inorganic sheets, expanded graphite sheets, etc. can be used, but heat resistance and sealing properties can be used. In view of this, it is preferable to use an expanded graphite sheet. As the expanded graphite sheet, a sheet prepared by a known manufacturing method can be used. For example, graphite with a highly developed crystal structure, such as natural graphite, quiche graphite, or pyrolytic graphite, is immersed in a strongly oxidizing solution such as a mixture of concentrated sulfuric acid and nitric acid, or a mixture of concentrated sulfuric acid and potassium permanganate. Then, a graphite intercalation compound is formed, washed with water and then rapidly heated, and a sheet obtained by cold working graphite having a compressive property in an insect shape in which the c-axis direction of the graphite crystal is expanded is used.

[0010] In the present invention, a resin containing dihydrobenzoxazine rings shown above Symbol to bond laminating the reinforcing core material and the sealing material as an adhesive. When this adhesive is used, volatile by-products such as condensed water are not generated at the time of curing, so that a sheet-like composite material having good adhesion can be obtained without swelling of the sealing material. Further, a sheet-like composite material using this adhesive is effective as a gasket to be used at high temperatures because of its excellent heat resistance.

The resin containing a dihydrobenzoxazine ring used in the present invention is represented by the general formula (A)

Embedded image (Wherein the hydrogen bonded to the aromatic ring is
May be substituted with a substituent except for one of the G-positions) and
General formula (B)

Embedded image (Wherein R ¹ is a hydrocarbon group, and water bonded to an aromatic ring is
May be substituted with a substituent).
Is 4/1 to 1 in the molar ratio of general formula (A) / general formula (B).
A resin containing 1/9 is used.

[0012]

The above general formulas (A) and (B)
The substituent in the chemical structural unit represented by is not particularly limited, but a preferable example is an alkyl group such as a methyl group and an ethyl group. In the general formula (A), one of the ortho positions of the hydroxyl group preferably has hydrogen for a curing reaction. When the number of the general formula (A) contained in one molecule is m and the number of the general formula (B) is n in one molecule, m ≧ 1, n
≧ 1 and m + n ≧ 2, but 10 ≧ m in number average
It is preferable that + n ≧ 3 in terms of the properties of the cured product, for example, heat resistance.

The above chemical structural units may be directly bonded to each other, or may be bonded via an organic group. Preferred examples of the organic group include an alkylene group and a xylylene group.

Embedded image (Where R ² represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a phenyl group or a substituted phenyl group), a chain alkylene group having 5 to 20 carbon atoms, or the like. No. This can be selected depending on the type of the compound having a phenolic hydroxyl group (described later) to be used.

The resin containing a dihydrobenzoxazine ring can be synthesized, for example, from a compound having a phenolic hydroxyl group, formaldehydes, and primary amines. This resin causes a ring-opening polymerization reaction by heating,
A crosslinked structure having excellent properties is formed without generating volatile components. As a method for producing a resin containing a dihydrobenzoxazine ring using each of the above materials, a mixture of a compound having a phenolic hydroxyl group and a primary amine is preferably added to formaldehydes heated to 70 ° C. or more, Preferably 70 to 110 ° C, more preferably 90
The reaction can be carried out at a temperature of １００100 ° C., preferably for 20-120 minutes, and then dried under reduced pressure at a temperature of preferably 120 ° C. or lower.

Examples of the compound having a phenolic hydroxyl group include a phenol novolak resin, a resol resin, a phenol-modified xylene resin, an alkylphenol resin,
Examples thereof include phenol resins such as melamine phenol resins and polybutadiene-modified phenol resins, bisphenol compounds, biphenol compounds, trisphenol compounds, and tetraphenol compounds. As the formaldehyde, in addition to formaldehyde, those that generate formaldehyde such as paraformaldehyde and hexamethylenetetramine can be used.

Specific examples of the primary amine include aliphatic amines such as methylamine, ethylamine, propylamine and cyclohexylamine, and aromatic amines such as aniline and substituted aniline. Aliphatic amines are preferred from the viewpoint of curability, and aromatic amines are preferred from the viewpoint of heat resistance. Each material is a compound having a phenolic hydroxyl group,
Formaldehydes and primary amines are used in a ratio of not less than 0.2 to 0.9 moles of primary amines and 1 mole of formaldehyde per mole of hydroxyl groups of the compound having a phenolic hydroxyl group. The reaction is preferable in terms of the adhesiveness of the obtained resin.

In the present invention, by using the resin containing a dihydrobenzoxazine ring as the adhesive, excellent heat resistance can be obtained and the generation of volatile gas during curing can be suppressed. It is possible to suppress the occurrence of swelling of the material, improve the adhesion between the reinforcing core material and the sealing material, and improve characteristics such as sealing properties. The adhesion between the reinforcing core material and the sealing material is achieved by applying the resin containing a dihydrobenzoxazine ring to one or both of the reinforcing core material and the sealing material, and then laminating the reinforcing core material and the sealing material alternately, and applying heat. This can be achieved by crimping.

The resin containing a dihydrobenzoxazine ring to be applied may be in the form of a powder or may be dissolved in a solvent such as methyl ethyl ketone to form a varnish. The varnish can be applied by a known method such as spraying. The powdered material can be applied by a method such as sprinkling with a sieve or electrostatic adhesion. The amount of coating is preferably from 0.01 to 50 g / m ² from the viewpoint of room temperature adhesive strength and heat bond strength, 0.1 to 10 g / m ²
Is more preferred.

[0020] As a method of thermocompression bonding, for example, heat press method, or a Turkey using methods such as heating roll method.
The heating temperature is preferably from 150 to 250C. The bonding may be performed for each layer, or may be performed after all the layers are laminated. In the sheet-like composite material of the present invention, one or both surface layers are made to be a sealing material in terms of sealing properties. When only one surface layer is a sealing material, it is preferable to use two or more sheet-like composite materials of the present invention in combination to form a gasket. Examples of the sheet-like composite material of the present invention, a shape in which a layer of a reinforcing core material and a sealing material are laminated,
Examples include a three-layer shape in which a sealing material is attached to both sides of a single reinforcing core material, and a shape including more layers (alternately four layers, five layers, six layers, and seven layers).

The sheet-like composite material obtained as described above can be processed into a desired shape to form a gasket. In addition, various packing materials can be formed by processing into a desired shape.

[0022]

Next, embodiments of the present invention will be described. Example 1 (1) Preparation of resin containing dihydrobenzoxazine ring Phenol 1.9 kg, formalin (37% by weight aqueous solution)
1.0 kg and 4 g of oxalic acid were charged into a 5-liter flask and reacted at reflux temperature for 6 hours. Next, 66 inside
Unreacted phenol and water were removed by reducing the pressure to 66.1 Pa (50 mmHg) or less to synthesize a phenol novolak resin. The obtained resin had a softening point of 84 ° C. (ring and ball method) and a trinuclear to polynuclear / binuclear ratio of 92/18 (peak area ratio by gel permeation chromatography).

Next, 1.70 kg (corresponding to 16 mol of hydroxyl groups) of the synthesized phenol novolak resin was mixed with 0.93 kg (corresponding to 10 mol) of aniline, and the mixture was heated at 80 ° C. for 5 minutes.
The mixture was stirred for an hour to prepare a uniform mixed solution. Next, 1.62 kg of formalin was charged into a 5-liter flask, and 90
C., and the above novolak / aniline mixed solution was added little by little over 30 minutes. Reflux temperature is maintained for 30 minutes after the end of the addition and then 666 for 2 hours at 100 ° C.
Reduce the pressure to 6.1 Pa (50 mmHg) or less to remove condensed water,
A resin containing a dihydrobenzoxazine ring in which 71% of the reactive hydroxyl groups were dihydrobenzoxazinated was obtained. That is, the above-mentioned resin containing a dihydrobenzoxazine ring containing a dihydrobenzoxazine ring has a molar ratio of the aforementioned general formula (A) and the general formula (B) of 1 for the former / the latter.
/2.45.

The amount of the hydroxyl group capable of reacting in the phenol novolak resin is calculated as follows. That is, 1.70 kg (corresponding to 16 moles of hydroxyl groups) of the phenol novolak resin was reacted with 1.4 kg (corresponding to 16 moles) of aniline and 2.59 kg of formalin, and a dihydrobenzoxazine ring was introduced into all of the reactive hydroxyl groups. The synthesized resin was synthesized. Excess aniline and formalin were removed during drying, yielding 3.34 kg. This indicates that the amount of the hydroxyl group capable of reacting in the phenol novolak resin was 14 mol, and the dihydrobenzoxazine was cyclized.

(2) Production of sheet-like composite material The obtained dihydrobenzoxazine resin was pulverized using a ball mill to obtain a powdery resin having an average particle diameter of 50 μm. On the other hand, the expanded graphite powder was compressed with a compression roll to obtain an expanded graphite sheet having a density of 0.8 g / cm ³ and a plate thickness of 0.19 mm. Next, the powdery dihydrobenzoxazine resin was dropped from the upper portion of the expanded graphite sheet in an amount of 1 g / m ^{2 on} one surface of the expanded graphite sheet to adhere thereto, and then heated to 100 ° C. with a resin melting device. The powdered dihydrobenzoxazine resin was melted, and then allowed to cool to room temperature to obtain an expanded graphite sheet with a resin to which the resin was fixed. Next, on the both surfaces of SUS301 (stainless steel 301) having a plate thickness of 0.2 mm, the above-mentioned expanded graphite sheet with resin is laminated with the surface on which the resin is adhered to the inside, and the temperature is 200 ° C. and the pressure is They were bonded under pressure of .45 MPa. Thereafter, the expanded graphite sheet was compressed through a roll to finish the expanded graphite sheet layer to a thickness of 0.15 mm and a density of 1.0 g / cm ³ to obtain a gasket material having an overall thickness of 0.5 mm.

Example 2 Example 1 was applied to both sides of a polyethylene terephthalate film (Lumirror, trade name, manufactured by Toray Industries, Ltd.) having a thickness of 200 μm.
The expanded graphite sheet with resin obtained in step 2 is laminated with the surface on which the resin is adhered facing the inside, and pressurized at a temperature of 200 ° C. and a pressure of 2.45 MPa with a hot press to expand the resin on both sides of the polyethylene terephthalate film. A graphite sheet was attached. Thereafter, the expanded graphite sheet was compressed through a roll to finish the expanded graphite sheet layer to a thickness of 0.15 mm and a density of 1.0 g / cm ³ to obtain a gasket material having an overall thickness of 0.5 mm.

Comparative Example 1 A phenol resin varnish (trade name V, manufactured by Hitachi Chemical Co., Ltd.) was used as an adhesive on both sides of SUS301 having a thickness of 0.2 mm.
P11-N). The surface coated with this phenolic resin varnish has a density of 0.8 g / cm ³ and a thickness of 0.19 mm.
Of expanded graphite sheets (trade name: Carbofit, manufactured by Hitachi Chemical Co., Ltd.), and pressurized with a hot press at a temperature of 180 ° C. and a pressure of 2.45 MPa (25 kgf / cm ² ) to form SUS
An expanded graphite sheet was adhered to both surfaces of 301. Thereafter, the expanded graphite sheet was compressed through a roll to finish the expanded graphite sheet layer to a thickness of 0.15 mm and a density of 1.0 g / cm ³ to obtain a gasket material having an overall thickness of 0.5 mm.

Comparative Example 2 Both sides of SUS301 having a thickness of 0.25 mm have a thickness of 30 μm.
m fluoro rubber (manufactured by Nippon Zeon Co., Ltd., trade name Nipol
CMF70) was applied to provide a rubber layer to obtain a gasket material having an overall thickness of 0.31 mm.

Next, the gasket materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated by measuring appearance, antifreeze sealing property and heat resistance (stress relaxation rate). The antifreeze sealing property is as follows. A gasket material is punched out into a ring shape having an outer diameter of 50 mm and an inner diameter of 34 mm, and this is sandwiched between flanges having a surface roughness of 10S and tightened with a surface pressure of 2.94 MPa (30 kgf / cm ² ). The internal pressure of an aqueous solution of ethylene glycol having a concentration of 50% by volume was applied to the sample, and the presence or absence of leakage of the solution to the outer diameter side was confirmed. The heat resistance (stress relaxation rate) was determined by measuring the reduction rate of the tightening force after the gasket material was tightened at a surface pressure of 20.58 MPa (210 kgf / cm ² ) and heat-treated at 200 ° C. for 22 hours. Table 1 shows the test results.

[0030]

[Table 1]

Example 3 Production of Sheet Composite Material The resin containing a dihydrobenzoxazine ring prepared in Example 1 was dissolved in methyl ethyl ketone (MEK) (resin concentration: 10% by weight) to obtain an adhesive. After applying this adhesive to both surfaces of SUS301 (stainless steel 301) having a plate thickness of 0.2 mm by spraying (resin coating amount: 2 g / m ² ), 80
The MEK was dried by heat treatment at 10 ° C. for 10 minutes to prepare a coated plate. At this time, the thickness of the adhesive applied to the SUS301 surface was 18 μm on one side. A 1.0 mm thick fluoro rubber sheet (trade name: VALQUA No.
4010, manufactured by Nippon Valqua Industry Co., Ltd.), and the temperature was 180 ° C. and the pressure was 0.98 MPa (10 kgf)
/ cm ² ), and a fluororubber sheet was bonded to both surfaces of SUS301 to obtain a sheet-like composite material having a thickness of 2.2 mm.

Example 4 Through the same steps as in Example 3, a SUS having a thickness of 0.2 mm
A coated plate was prepared by coating a resin containing a dihydrobenzoxazine ring on both surfaces of an expanded graphite sheet 301. An expanded graphite sheet having a plate thickness of 1.0 mm and a density of 1.0 g / cm ³ (trade name) was formed on both surfaces of the coated plate. Carbofit, Hitachi Chemical Co., Ltd.)
180 ° C and 0.98MPa pressure (1
Under pressure of 0 kgf / cm ² ), expanded graphite sheets were adhered to both sides of SUS301 to obtain a sheet-like composite material having a thickness of 2.2 mm.

Comparative Example 3 A phenol resin varnish (trade name: VP-11N, Hitachi Chemical Co., Ltd.) was applied to both sides of SUS301 having a thickness of 0.2 mm.
Was spray-coated as an adhesive, and dried at 80 ° C. to prepare a coated plate. The thickness of the coated plate is 1.
0mm fluoro rubber sheet (Vulker No.401, trade name)
0, manufactured by Nippon Valqua Industry Co., Ltd.), and the temperature is 180 ° C. and the pressure is 0.98 MPa (10 kgf / cm ² ) by a hot press.
And a fluororubber sheet was adhered to both surfaces of SUS301 to obtain a sheet-like composite material having a thickness of 2.2 mm.

Comparative Example 4 A phenol resin varnish (trade name: VP-11N, manufactured by Hitachi Chemical Co., Ltd.) as an adhesive was applied to both surfaces of SUS301 having a thickness of 0.2 mm by spraying, followed by drying at 80 ° C. To produce a coated plate. An expanded graphite sheet with a thickness of 1.0 mm (trade names Carbofit, Hitachi Chemical Co., Ltd.)
And pressurized at 180 ° C. and 0.98 MPa (10 kgf / cm ² ) with a hot press.
An expanded graphite sheet is adhered to both surfaces of S301, and the sheet thickness is 2.
A 2 mm sheet composite was obtained.

COMPARATIVE EXAMPLE 5 An epoxy resin varnish (trade name: Sumitac EA, manufactured by Sumitomo Bakelite Co., Ltd.) was applied by spraying to both surfaces of SUS301 having a thickness of 0.2 mm and then dried at 80 ° C. A work board was produced. Both sides of this coated plate have a thickness of 1.0
mm expanded graphite sheet (trade name: Carbofit, manufactured by Hitachi Chemical Co., Ltd.) and the temperature is 180
The expanded graphite sheet was adhered to both surfaces of SUS301 by pressing under the conditions of ° C and a pressure of 0.98 MPa (10 kgf / cm ² ) to obtain a sheet-like composite material having a plate thickness of 2.2 mm.

Next, the appearance, adhesion and heat resistance of the sheet-like composite materials obtained in Examples 3 and 4 and Comparative Examples 3 and 5 were evaluated as gasket materials. The heat resistance was measured by subjecting the produced gasket material to a heat / cool cycle test of heat treatment at 300 ° C. for 10 minutes and cooling at room temperature for 10 minutes to measure the number of times until the SUS301 and the sealing material were peeled off. Table 2 shows the test results.

[0037]

[Table 2]

[0038]

The sheet-like composite material according to claim 1 is excellent in appearance, adhesiveness, heat resistance, sealability and strength, and is useful as a material for producing gaskets, packings and the like. The sheet-like composite material according to the second aspect has the effects of the sheet-like composite material according to the first aspect, and particularly has a large effect of improving the sealing property and the heat resistance. The gasket according to claim 3 is excellent in appearance, adhesiveness, heat resistance, sealability and strength.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09K 3/10 C09K 3/10 R F16J 15/10 F16J 15/10 W 15/12 15/12 A (72) Inventor Kazuo Yamada 3-3-1 Ayukawacho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd., Yamazaki Plant (72) Inventor Teruki Aizawa 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd., Shimodate Plant (72) Inventor Yasuyuki Hirai 1500 Ogawa Oaza, Shimodate City, Ibaraki Prefecture Investigator, Toshiko Nakata, Hitachi Chemical Co., Ltd. Shimodate Plant (56) References JP-A-2-107869 (JP, A) JP-A-6-88062 (JP, A) JP-A-63-295691 (JP, A) JP-A-3-229069 (JP, A) JP-A-49-47378 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C09J 1/00-201/10 C08L 1/00-101/16 F16J 15/00-15/56

Claims (3)

(57) [Claims] The method according to claim 1 reinforcing core material and the sealing material, the general formula as the resin containing dihydrobenzoxazine rings in a molecule (A) ## STR1 ## (Wherein the hydrogen bonded to the aromatic ring is
May be substituted with a substituent except for one of the G-positions) and
The general formula (B) ## STR2 ## (Wherein R ¹ is a hydrocarbon group, and water bonded to an aromatic ring is
May be substituted with a substituent).
Is 4/1 to 1 in the molar ratio of general formula (A) / general formula (B).
A sheet-like composite material formed by laminating and bonding one or both surface layers so as to be a sealing material using a resin containing 1/9 as an adhesive. 2. The sheet-like composite material according to claim 1, wherein the sealing material is an expanded graphite sheet. 3. A gasket made by processing the composite material sheet of the mounting according to claim 1 or 2 SL.