JP2006218630A5 - - Google Patents

Description

Nitrile rubber-metal laminated gasket material

  The present invention relates to a nitrile rubber-metal laminated gasket material. More specifically, the present invention relates to a nitrile rubber-metal laminated gasket material suitably used as an engine cylinder head gasket or the like.

  Stainless steel is used for gaskets for engine cylinder heads that require LLC (long life coolant) resistance. However, even if vulcanized adhesive is applied directly to stainless steel and rubber is vulcanized and bonded, it is resistant. The liquid adhesion durability is poor, and adhesion peeling occurs when the immersion test is performed.

  As a countermeasure against this, as a pretreatment for applying vulcanized adhesive, chromate treatment is applied to the surface of stainless steel to improve resistance to water and LLC aqueous solution, but chromium-free treatment that does not contain hexavalent chromium. The demand for is getting stronger.

The present applicant has previously made a gasket material for an engine cylinder head in which a silane-based primer, an phenolic resin-based adhesive, and a nitrile rubber containing an organic titanium compound and a quaternary ammonium salt compound are sequentially laminated on a stainless steel plate, stainless steel Engine cylinder head gasket material, alkyl-modified novolac type, in which an organic titanium compound and a silane-based primer containing an ultrafine metal oxide with an average particle size of 40 mm or less, a phenolic resin-based adhesive, and nitrile rubber are sequentially laminated on a steel plate It has been proposed to use a vulcanized adhesive composition comprising a phenolic resin and a specific resol type phenolic resin as a phenolic adhesive when vulcanizing and bonding a metal plate and a nitrile rubber.
JP 2004-11576 A JP 2004-76699 A JP 2004-277435 A

  A nitrile rubber-metal laminate obtained by vulcanizing and bonding a stainless steel plate and nitrile rubber in this way can be used for a long period of time at a fairly high temperature in immersion tests in various simple aqueous solutions such as water and LLC aqueous solutions. It has been confirmed to withstand. However, in such nitrile rubber-metal laminates and gaskets using them as a raw material, dissimilar metals are often in contact with each other in the same liquid in the actual use environment. There is a phenomenon in which an electric potential is generated between the plate and the dissimilar metal and adhesion peeling is promoted.

  When the applicant uses a nitrile rubber-stainless steel laminate in contact with an electrolyte such as water or an LLC aqueous solution, if the metal is susceptible to corrosion, such as aluminum or iron, There is a phenomenon in which an electric potential is generated between the aluminum and iron, causing a corrosion reaction (anode reaction), and a cathode reaction occurs on the stainless steel surface of the laminate, which causes peeling. I found. As a prominent example, when using a nitrile rubber-stainless steel laminate as a gasket for an aluminum engine cylinder head, the blister and adhesion can be done in a shorter period of time than when the laminate is immersed in the same temperature condition. Examples include phenomena such as peeling.

A method that can reproduce such a phenomenon in the laboratory is necessary. For this purpose, a rubber stainless steel laminate and a metal having a smaller ionization energy than hydrogen, such as an aluminum plate, are immersed in the test solution, and in this case, near the top. In a semi-immersed state so as to be located above the liquid level, the exposed portions of the immersion liquid are brought into contact directly or via a conductive wire, for example, a rubber stainless steel laminate and a metal plate having a smaller ionization energy than hydrogen As a state of being immersed in a test solution so as to be in contact with an inverted V shape, after being immersed for a predetermined time in a state where they are not in contact with each other, the liquid resistance of the test liquid is measured or evaluated for the deterioration of the characteristic value of the laminate A confirmation evaluation method has been proposed previously .
JP 2005-49257 A

  The object of the present invention is to prevent adhesion peeling even when used in the electrolyte at the same time as a dissimilar metal in an actual use environment as a gasket, and to maintain sufficient adhesion even in the above test liquid resistance confirmation evaluation method. It is an object of the present invention to provide a nitrile rubber-metal laminated gasket material that can be evaluated as being.

  An object of the present invention is to provide a nitrile rubber obtained by sequentially laminating a surface treatment agent layer containing a zirconium element, a phosphorus element and an aluminum element, a silica-containing resin-based vulcanized adhesive layer, and a nitrile rubber layer on a stainless steel plate. Achieved by metal laminated gasket material.

  The nitrile rubber-metal laminated gasket material according to the present invention is bonded even if it is used at the same time as a metal different from stainless steel such as aluminum and iron in an electrolyte such as water and LLC aqueous solution in an actual use environment as a gasket. Does not peel off. In addition, in the test liquid resistance confirmation evaluation method, sufficient water resistance and LLC resistance are maintained. Furthermore, even in a nitrile rubber-metal laminated gasket material in which nitrile rubber is vulcanized and bonded to chromate-treated stainless steel, peeling occurs when such a test liquid resistance confirmation evaluation method is performed for a long time. This is not the case with the nitrile rubber-metal laminated gasket material, and a chromium-free nitrile rubber-metal laminated gasket material having water resistance equivalent to that of the chromate-treated rubber metal laminated plate can be provided.

  Therefore, the nitrile rubber-metal laminated gasket material of the present invention has the heat resistance and LLC resistance necessary for an engine cylinder head gasket and has an excellent performance balance, so it is not only used effectively for this kind of application. It can also be used as rubber metal composite parts for automobiles, industrial machines, etc. that require water resistance.

  As the metal steel plate, iron, aluminum, copper and the like, alloys thereof, stainless steel plates, and the like are used. Generally, stainless steel plates such as SUS301, SUS301H, SUS304, and SUS430 are used. On these steel plates, a surface treatment agent layer containing each element of zirconium, phosphorus and aluminum is formed.

  In this surface treatment agent layer, the element mass ratio of zirconium and aluminum is 90:10 to 10:90, preferably 70:30 to 30:70, and the element mass ratio of zirconium and phosphorus is 95: 5 to 60:40, Preferably, it is formed at a ratio of 90:10 to 68:32. When the amount of aluminum is larger than this, film formation is poor or the film is easily detached, whereas when it is less than this, heat resistance and water resistance are lowered. On the other hand, if the amount of phosphorus is larger than this, the heat resistance is lowered, while if it is smaller than this, film formation is poor.

  The zirconium component in these films is present in the form of zirconium phosphate or zirconium oxide, but is preferably present in the form of zirconium phosphate. As a component for forming these, a treatment liquid containing zirconium nitrate, zirconium acetate, zirconium sulfate, ammonium zirconium carbonate, zirconium oxide or the like is used, but a treatment liquid containing ammonium zirconium carbonate is preferably used. Aluminum is present in the film by a treatment solution containing aluminum silicate, alumina (aluminum oxide), aluminum hydroxide, aluminum sulfate or the like, but is preferably present in the form of aluminum oxide. The phosphorus component in the film is supplied by adding phosphoric acid, and the amount added is adjusted so that the Zr: P mass ratio is 95: 5 to 60:40.

  In addition, in the surface treatment agent, in order to enhance the effect and ensure the stability of the liquid, inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, organic acids such as formic acid, acetic acid, ammonium hydroxide (ammonia water) Nitrogen-containing alkaline compounds such as ethylenediamine, triethylenetetramine, morpholine and choline can also be added.

The surface treatment agent is a solution in which the above components are dissolved or dispersed in water, and is coated on one side by a method such as spraying, dipping, brushing, or roll coater on a steel plate degreased with alkali or the like, preferably a stainless steel plate. The amount is about 10 to 1000 mg / m ² , preferably about 50 to 500 mg / m ² , dried at room temperature or warm air, and then baked at about 100 to 250 ° C. for about 0.5 to 20 minutes. Is implemented.

  A silica-containing resin-based vulcanized adhesive layer is formed on a steel plate that has been subjected to a surface treatment, preferably a stainless steel plate.

Silica (silicon oxide) is a dispersion of dry or wet silica having a SiO ₂ content of 85% or more in an organic solvent or water, preferably high-purity anhydrous silica fine particles in an organic solvent or water. So-called colloidal silica dispersed in colloidal form is used. The colloidal silica has an average particle diameter of 1 to 50 nm, preferably 10 to 30 nm, and is dispersed in an organic solvent such as methanol, methyl ethyl ketone, or methyl isobutyl ketone, and is a commercially available product, for example. Methanol silica sol (Nissan Chemical Industries product: Dispersed in methanol at a solid concentration of 30% by weight), Snowtex MEK-ST (Company product; Dispersed in methyl ethyl ketone at a solid content of 30% by weight), Snowtex MIBK -ST (Company product; dispersed in methyl isobutyl ketone at a solid content of 30% by weight) is used.

Such silica is generally used in a state where it is dispersed in a thermosetting phenol resin or in combination with an unvulcanized nitrile rubber (compound) .

  As a phenolic resin used as one component of the vulcanizing adhesive, a phenolic resin having a dihydrobenzoxazine ring is also used in addition to a novolac type phenolic resin, and a resole type phenolic resin is used in combination with these phenolic resins. Sulfur can also be used by adding nitrile rubber or a compound thereof.

  As novolak type phenolic resin, two phenolic hydroxyl groups such as phenol, p-cresol, m-cresol, p-tert-butylphenol, p-phenylphenol, bisphenol A, etc., at the o-position and / or p-position Alternatively, a softening point obtained by subjecting phenols having three substitutable nuclear hydrogen atoms or a mixture thereof and formaldehyde to a condensation reaction in the presence of an acid catalyst such as hydrochloric acid or oxalic acid is about 80 to 150 ° C. A resin having a softening point of 100 ° C. or higher produced from m-cresol, a p-cresol mixture and formaldehyde is preferably used.

  As the resol type phenol resin, one obtained by reacting the above condensation reaction in the presence of an alkali catalyst such as sodium hydroxide, sodium carbonate, magnesium hydroxide, ammonia or the like is used.

特開２００４−８３６２３号公報 In addition, as the thermosetting phenol resin having a dihydrobenzoxazine ring, any thermosetting phenol resin having a dihydrobenzoxazine ring and being cured by a ring-opening reaction of the dihydrobenzoxazine ring should be used. For example, a dihydro-2H-1,3-benzoxazine derivative is synthesized from a compound having a phenolic hydroxyl group, a primary amine and formaldehyde, as shown in the following formula.

JP 2004-83623 A

  The compound having a phenolic hydroxyl group must have a hydrogen atom bonded to at least one o-position with respect to the phenolic hydroxyl group of the aromatic ring, and preferably a plurality of phenolic hydroxyl groups in the molecule. Existing multifunctional phenols are used. Specifically, phenols such as catechol, resorcinol and hydroquinone, dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene and 2,6-dihydroxynaphthalene, bisphenols such as bisphenol A and bisphenol F, novolac type or resole type phenol Examples thereof include phenol resins such as resin, melamine phenol resin and alkylphenol resin.

  Examples of primary amines include aromatic amines such as aniline and toluidine, and aliphatic amines such as methylamine and ethylamine.

  Two moles or more of formaldehyde is used for each mole of the compound having a phenolic hydroxyl group and the primary amine, and the reaction temperature is about 70 to 130 ° C., preferably about 90 in the presence of an oxalic acid catalyst. After reacting at ~ 110 ° C for about 1/3 to 4 hours, remove the unreacted phenolic compounds, primary amines, formaldehyde, etc. under reduced pressure at 120 ° C or less, and heat with dihydrobenzoxazine ring A curable resin is obtained.

  As the resin component, one in which a resol type phenol resin is used in combination at a ratio of about 1 to 500 parts by weight, preferably about 10 to 100 parts by weight, with respect to 100 parts by weight of a novolak type phenol resin is generally used. The combined use of the resol type phenolic resin brings about the effect of further improving the water-resistant adhesiveness. However, when it is used in a proportion higher than this, the heat resistant adhesiveness is lowered. Silica is used in an amount of about 1 to 1000 parts by weight, preferably about 10 to 100 parts by weight, based on 100 parts by weight of the novolac type phenol resin. When the proportion of silica is larger than this, the initial adhesiveness is lowered, whereas when used at a proportion smaller than this, the water resistance is lowered.

  Further, nitrile rubber or a compound thereof is added at a ratio of about 1000 parts by weight or less, preferably about 10 to 100 parts by weight per 100 parts by weight of novolak type phenol resin. Addition of nitrile rubber (compound) further improves the heat-resistant adhesive property of the vulcanized adhesive layer, but addition in a proportion higher than this decreases the water-resistant adhesive property.

Silica-containing resin-based vulcanized adhesives generally use alcohol-based organic solvents such as methanol, ethanol, and isopropanol, ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, or a mixed solvent thereof. Prepared as a 10 wt% organic solvent solution, applied in the same manner as in the case of the surface treatment agent at a weight per side of about 50 to 2000 mg / m ² , dried at room temperature or warm air, and then about 100 to A baking process is performed at 250 ° C. for about 1 to 20 minutes.

On the vulcanized adhesive layer formed in this way, an unvulcanized nitrile rubber compound is formed on both sides with a vulcanized layer having a thickness of about 5 to 120 μm on one side. It is applied as an organic solvent solution . The nitrile rubber may have a cured product having a hardness (durometer A) of 80 or more and a compression set (100 ° C., 22 hours) of 50% or less, and may be a hydrogenated nitrile rubber. Although it is not particularly limited by the content of the compound, it can be used as a compound using a sulfur-based vulcanizing agent such as sulfur or tetramethylthiuram monosulfide, but preferably an organic peroxide is used as a crosslinking agent. Used as an unvulcanized nitrile rubber compound. Examples of such peroxide-crosslinked unvulcanized nitrile rubber compounds include the following blending examples.
(Formulation example)
NBR (JSR product N235S) 100 parts by weight
SRF carbon black 80 〃
Calcium carbonate 80 〃
Powdered silica 20 〃
Zinc oxide 5 〃
Anti-aging agent (Ouchi Emerging Chemical Product Nocrack 224) 2 〃
Triallyl isocyanurate 2 〃
1,3-bis (tert-butylperoxy) isopropylbenzene 2.5 〃
Plasticizer (Bayer's product Bucanol OT) 5 〃

The applied unvulcanized rubber layer is dried at a temperature of room temperature to about 100 ° C. for about 1 to 15 minutes, and alcohols such as methanol and ethanol used as an organic solvent , and ketones such as methyl ethyl ketone and methyl isobutyl ketone After volatilizing aromatic hydrocarbons such as toluene and xylene or a mixed solvent thereof, heat vulcanize at about 150 to 230 ° C for about 0.5 to 30 minutes, pressurize and vulcanize as necessary Is also done. The vulcanized nitrile rubber layer preferably has a hardness (durometer A) of 80 or more and a compression set (100 ° C., 22 hours) of 50% or less for use as a gasket, and needs to prevent adhesion. In some cases, an anti-sticking agent can be applied to the surface.

The anti-tacking agent is used for the purpose of preventing sticking between rubbers or between rubber and metal, and any anti-tacking agent can be used as long as it can form a film on the vulcanized nitrile rubber layer. , Fluorine-based, graphite-based, amide, paraffin-based wax-based, polyolefin-based or polybutadiene-based materials, etc., preferably liquid 1,2-polybutadiene hydroxyl group-containing materials, 1,2-polybutadiene isocyanate group-containing materials And an anti-adhesive agent comprising an organic solvent dispersion of a polyolefin resin.
Japanese Patent Laid-Open No. 7-165953

  Next, the present invention will be described with reference to examples.

Examples 1-5, Comparative Examples 1-7
On an alkali degreased SUS301 stainless steel plate (thickness 0.2 mm), ammonium zirconium carbonate, phosphoric acid and phosphoric acid were added so that the element mass ratio of Zr, P, and Al in the surface treatment agent film was the ratio shown in Table 1. A surface treatment agent with an adjusted amount of alumina was applied so that the amount per unit area of the surface was 200 to 300 mg / m ² , and dried at 200 ° C. for 1 minute. The surface treatment agent was prepared with ammonium hydroxide so as to have a pH of 6 to 10.
Table 1
Element mass ratio
Surface treatment agent component composition ratio Zr: P Zr: Al
Surface treatment agent Zr P Al Zr P Zr Al
[Zr: P]
A (Lower limit) 37 16 47 70 30 44 56
B (upper limit) 30 2 68 94 6 31 69
C (intermediate) 35 10 55 78 22 39 61
[Zr: Al]
D (Lower limit) 10 2 88 82 18 10 90
E (upper limit) 72 20 8 78 22 90 10
F (Al) 4 1 95 80 20 4 96
G [Al low] 67 27 6 71 29 92 8
H (P) 30 30 40 50 50 43 57
I [P less] 52 2 46 96 4 53 47
J (without Al) 80 20 − 80 20 100 −
K (without Zr) − 15 85 − 100 − 100
L (without P) 45 0 55 100 − 45 55
On the steel sheet coated with the surface treatment agents A to E (Examples 1 to 5) and F to L (Comparative Examples 1 to 7) ,
100 parts by weight of novolak type phenolic resin Resole type phenolic resin (30% by weight methanol solution) 150 〃
Colloidal silica (Nissan Chemicals Snowtex MEK-ST; 100 〃
(Methyl ethyl ketone solution with a solid content of 30% by weight)
Nitrile rubber compound of the above blending example 133 〃
(30 wt% methyl ethyl ketone solution)
Methyl ethyl ketone 3815 〃
The vulcanized adhesive A was applied so that the coating amount was 1500 mg / m ² , dried at room temperature, and then baked at 220 ° C. for 5 minutes.

On this vulcanized adhesive-coated steel sheet, a 25% by weight toluene-methyl ethyl ketone (9: 1 weight ratio) mixed solvent solution of the nitrile rubber compound of the above blending example was applied and dried at 60 ° C. for 15 minutes to have a single-side thickness of 20 μm. After the unvulcanized rubber layer was formed, pressure vulcanization was performed under the conditions of 220 ° C., 60 kgf / cm ² (5.88 MPa) for 2 minutes to prepare a nitrile rubber-metal laminated gasket material.

The gasket material was subjected to the following various tests.
Water resistance test: A rubber stainless steel laminated gasket material and an aluminum plate are immersed in a 1% by weight sodium hydrogen carbonate aqueous solution, and the immersion liquid is exposed in a semi-immersed state so that the top is located above the liquid level. After being immersed in the liquid without being in contact with each other at 90 ° C for 70 hours or 240 hours, the gasket material was peeled off according to JIS K5600-5-6, and the following Grade 5: The edges of the cuts are completely smooth and no grid eyes peel off. 〃 4: There is a small peeling of the coating film at the intersection of the cuts (peeling area ratio less than 5%)
３ 3: The film is peeled along the edge of the cut and / or at the intersection
(Peeling area ratio 5-15%)
〃 2: A large amount of peeling occurs partially or entirely along the edge of the cut of the coating film.
And / or various parts of the eye are partially or totally peeled off
(Area ratio 15-35%)
１ ： 1: There is large or partial peeling along the edge of the cut of the coating
And / or some of the eyes are partially or totally peeled (peeled area ratio 35%
more than)
LLC resistance test: The above Goban eye tape test was performed on gasket materials after being immersed in a 50% by weight aqueous solution of LLC liquid (Japan Chemical Product JCC310) at 150 ° C for 100 hours or 240 hours. Heat resistance test evaluated based on evaluation criteria: Gasket material is exposed to heat at 220 ° C for 100 hours or 240 hours, and then subjected to a bending resistance test (using a 4mm mandrel) in accordance with JIS K5600-5-1 Rating 5: No cracking or peeling 〃 4: Small cracks on the end face ： 3: Small cracks overall 〃 2: Overall cracks １ ： 1: Completely peeled off Have

Examples 6-10, Comparative Examples 8-14
In Examples 1 to 5 and Comparative Examples 1 to 7, a vulcanized adhesive B having the following composition was used in place of the vulcanized adhesive A.
100 parts by weight of novolak type phenolic resin Resol type phenolic resin (30% methanol solution) 33 〃
Colloidal silica (Snowtex MEK-ST) 100 〃
Nitrile rubber compound of the above blending example 133 〃
(30 wt% methyl ethyl ketone solution)
Methyl ethyl ketone 3234 〃

Examples 11-15, Comparative Examples 15-21
In Examples 1 to 5 and Comparative Examples 1 to 7, a vulcanized adhesive C having the following composition was used in place of the vulcanized adhesive A.
100 parts by weight of novolak type phenolic resin Resol type phenolic resin (30% by weight methanol solution) 333 〃
Colloidal silica (Snowtex MEK-ST) 100 〃
Nitrile rubber compound of the above blending example 133 〃
(30 wt% methyl ethyl ketone solution)
Methyl ethyl ketone 4734 〃

Examples 16-20, Comparative Examples 22-28
In Examples 1 to 5 and Comparative Examples 1 to 7, a vulcanized adhesive D having the following composition was used in place of the vulcanized adhesive A.
100 parts by weight of novolak type phenolic resin Resole type phenolic resin (30% by weight methanol solution) 150 〃
Colloidal silica (Snowtex MEK-ST) 33 〃
Nitrile rubber compound of the above blending example 133 〃
(30 wt% methyl ethyl ketone solution)
Methyl ethyl ketone 3479 〃

Examples 21-25, Comparative Examples 29-35
In Examples 1 to 5 and Comparative Examples 1 to 7, a vulcanized adhesive E having the following composition was used in place of the vulcanized adhesive A.
100 parts by weight of novolak type phenolic resin Resole type phenolic resin (30% by weight methanol solution) 150 〃
Colloidal silica (Snowtex MEK-ST) 333 〃
Nitrile rubber compound of the above blending example 133 〃
(30 wt% methyl ethyl ketone solution)
Methyl ethyl ketone 4984 〃

The test results obtained in the above examples and comparative examples are shown in Table 2 below.
Table 2
Water resistance test LLC resistance test Heat resistance test
Examples 70hr 240hr 100hr 240hr 100hr 240hr
Example 1 5 5 5 5 5 5
〃 2 5 5 5 5 5 5
３ 3 5 5 5 5 5 5
４ 4 5 5 5 5 5 4
〃 5 5 4 5 5 5 4
Comparative Example 1 3 2 2 1 1 1
〃 2 2 1 3 2 4 3
３ 3 3 2 4 3 1 1
４ 4 3 1 2 1 2 2
〃 5 1 1 2 1 3 2
６ 6 1 1 1 1 1 1
７ 7 1 1 1 1 2 1
Example 6 5 5 5 5 5 5
７ 7 5 4 5 5 5 5
〃 8 5 5 5 5 5 5
９ 9 5 4 5 5 5 4
〃 10 5 4 5 5 5 5
Comparative Example 8 2 1 1 1 1 1
９ 9 1 1 2 1 4 3
〃 10 2 1 3 2 2 1
〃 11 1 1 2 1 3 2
〃 12 1 1 2 1 4 3
〃 13 1 1 1 1 1 1
〃 14 1 1 1 1 2 1
Example 11 5 5 5 5 5 4
〃 12 5 5 5 5 5 4
〃 13 5 5 5 5 5 4
〃 14 5 5 5 5 5 4
〃 15 5 5 5 5 5 4
Comparative Example 15 3 1 2 1 2 1
〃 16 3 1 3 2 3 2
〃 17 4 2 4 3 2 1
〃 18 3 1 2 1 3 1
〃 19 1 1 2 1 2 1
〃 20 1 1 1 1 1 1
〃 21 1 1 1 1 2 1
Example 16 5 4 5 4 5 5
〃 17 5 4 5 4 5 5
〃 18 5 4 5 4 5 5
〃 19 5 3 5 3 5 5
〃 20 5 3 5 5 5 5
Comparative Example 22 1 1 1 1 2 2 1
〃 23 1 1 2 1 4 3
〃 24 3 1 3 2 2 1
〃 25 2 1 2 1 3 2
〃 26 1 1 1 1 3 2
〃 27 1 1 1 1 1 1
〃 28 1 1 1 1 2 1
Example 21 5 5 5 5 5 4
〃 22 5 5 5 4 5 4
〃 23 5 5 5 5 5 4
〃 24 5 5 5 4 5 3
〃 25 5 5 5 4 5 4
Comparative Example 29 3 1 2 1 2 1
〃 30 2 1 3 2 4 3
〃 31 4 2 4 3 2 1
〃 32 3 1 2 1 3 2
〃 33 1 1 2 1 3 2
〃 34 1 1 1 1 1 1
〃 35 1 1 1 1 2 1

Claims (1)

A nitrile rubber-metal laminated gasket material obtained by sequentially laminating a surface treatment agent layer containing a zirconium element, a phosphorus element and an aluminum element, a silica-containing resin-based vulcanized adhesive layer, and a nitrile rubber layer on a metal steel plate.