JP5526891B2 - Phenol resin / polyvinyl acetal resin adhesive - Google Patents

Description

  The present invention relates to a phenol resin / polyvinyl acetal resin-based adhesive, and particularly to a phenol resin / polyvinyl acetal resin-based adhesive that does not use an aromatic solvent or a chlorine-based solvent, which is considered to have a high environmental load.

  A phenol resin / polyvinyl acetal resin adhesive (phenolic-vinyl adhesive) is an adhesive having heat resistance of phenol resin and flexibility of polyvinyl acetal resin. It has heat resistance and toughness, and has excellent adhesion to metals.

  Copper-clad laminates for printed wiring are made by laminating copper foil and a phenolic resin base material. However, heat resistance is required because the circuit board is immersed in a solder bath, and holes are made in the circuit board. Toughness is required because it is processed. For this reason, as described in Patent Document 1 and Patent Document 2, a phenol resin / polyvinyl acetal resin-based adhesive has long been used for bonding a copper foil and a substrate such as a phenol resin.

  In addition, disc brakes and drum brakes for vehicles such as passenger cars and trucks are exposed to high temperatures around the disc or drum or friction material due to frictional heat generated when the brake friction material and the disc or drum come into contact with each other during brake operation. . A metal brake member such as a pressure plate and a friction material are often joined with an adhesive. Therefore, heat resistance is required for the adhesive used for assembling the braking member. On the other hand, the adhesive used for assembling the braking member is required to be flexible so that the braking member is not broken by an impact when the brake is applied. For this reason, as described in Patent Document 3, the phenol resin / polyvinyl acetal resin adhesive is also used for bonding a metal brake member and a friction material.

  When the phenol resin / polyvinyl acetal resin is used for the above-mentioned purposes, it is desirable to use it dissolved in a solvent. As described in Patent Documents 1 to 3, aromatic solvents such as toluene and halide solvents such as dichloromethane are used as the solvent. In particular, a mixed solvent of toluene and ethanol is used in many examples of patent documents.

  However, these solvents have environmental problems and should not be used. However, phenols and polyvinyl acetal resins are sufficiently dissolved in esters such as methyl acetate, ethyl acetate, and butyl acetate, and ketones such as methyl ethyl ketone and acetone, which are general industrial solvents and have low toxicity. I can't. In particular, when a polyvinyl formal resin having excellent heat resistance is used as the polyvinyl acetal resin, a solvent having a small environmental problem that can sufficiently dissolve the phenol resin / polyvinyl acetal resin has not been found.

  Patent Document 4 proposes a powdery phenol resin adhesive that does not use a solvent. This adhesive has the advantage that it can be bonded without volatilizing solvent or moisture, but it is difficult to adjust the coating amount, and when the coating surface is curved like a pressure plate for a drum brake, it cannot be easily applied. .

Japanese Examined Patent Publication No. 42-026400 Japanese Patent Publication No. 48-012068 JP 63-022882 A JP-A-5-65468

  An object of the present invention is to provide a solution-type adhesive which is a phenol resin / polyvinyl acetal resin adhesive and has low toxicity and environmental problems. Another object of the present invention is to provide a phenol resin / polyvinyl acetal resin adhesive having low toxicity and environmental problems, and to provide an adhesive having a hot adhesive strength and a normal adhesive strength after heat aging.

  The present inventor can dissolve the phenol resin / polyvinyl acetal resin as a solvent for the phenol resin / polyvinyl acetal resin, and can dissolve the phenol resin / polyvinyl acetal resin. And normal adhesion strength after heat aging was found to be excellent. That is, the present invention is the following phenol resin / polyvinyl acetal resin adhesive and a method for assembling a braking member using the adhesive.

(1) (A) 100 parts by weight of polyvinyl acetal resin,
(B) 30 to 300 parts by weight of phenol resin,
(C) Carbonate ester is contained in 100 to 500 parts by weight, and (D) methanol is contained in 10 to 200 parts by weight. A phenol resin / polyvinyl acetal resin adhesive.

(2) The phenol resin / polyvinyl acetal resin adhesive according to (1), wherein the polyvinyl acetal resin (A) is at least one selected from polyvinyl formal resins and polyvinyl butyral resins.

(3) The phenol resin / polyvinyl acetal resin adhesive according to (2), wherein the polyvinyl acetal resin (A) is a polyvinyl formal resin.

(4) The phenol resin / polyvinyl acetal resin adhesive according to (3), wherein the polyvinyl formal resin is a polyvinyl formal resin having a weight average molecular weight of 50,000 or more.

(5) The phenol resin / polyvinyl acetal resin adhesive according to any one of (1) to (4), wherein the (B) phenol resin is a resol type phenol resin.

(6) The carbonic acid ester (C) is at least one selected from ethylene carbonate, 1,2-propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. The phenol resin / polyvinyl acetal resin-based adhesive according to any one of the above.

(7) The phenol resin / polyvinyl acetal resin adhesive according to (6), wherein the carbonic acid ester (C) is dimethyl carbonate.

(8) The phenol resin / polyvinyl acetal resin adhesive according to any one of (1) to (7), which is used for assembling a braking member.

(9) A braking member assembly method comprising assembling a braking member using the phenol resin / polyvinyl acetal resin adhesive according to (8).

  The phenol resin / polyvinyl acetal resin adhesive of the present invention does not use toluene, xylene, dioxane and chlorinated solvents, so it reduces the environmental burden, and there are few problems in any of irritation, toxicity, environmental pollution, and odor. It has the effect of increasing safety. Moreover, the hot bond strength and the normal bond strength after heat aging are excellent, and it can be used as an adhesive for bonding a copper-clad laminate for printed wiring to a metal or as a brake member assembly.

It is sectional drawing of the disc brake 1 using the adhesive agent of this invention. It is sectional drawing of the drum brake 20 using the adhesive agent of this invention.

  The (A) polyvinyl acetal resin used in the present invention is a general term for resins obtained by acetalizing polyvinyl alcohol with an aldehyde.

（式中、Ｒ１は水素原子またはアルキル基を示す。）
で表されるビニルアセタール単位（１）を主体とし、一般式

で表されるビニルアルコール単位（２）、および場合により一般式

（式中、Ｒ２は水素原子、アルキル基またはアルコキシ基を示す。）
で表されるビニルカルボキシレート単位（３）を繰り返し単位として含む重合体が挙げられる。このポリビニルアセタール樹脂のうち、ビニルアセタール単位（１）を５０〜９０重量％、ビニルアルコール単位（２）を０．１〜２０重量％およびビニルカルボキシレート単位（３）を５〜２０重量％の割合でそれぞれ含むものは、入手が容易である。 Examples of the polyvinyl acetal resin include a general formula

(In the formula, R 1 represents a hydrogen atom or an alkyl group.)
Mainly composed of vinyl acetal unit (1) represented by general formula

A vinyl alcohol unit (2) represented by

(In the formula, R2 represents a hydrogen atom, an alkyl group or an alkoxy group.)
The polymer which contains the vinyl carboxylate unit (3) represented by these as a repeating unit is mentioned. In this polyvinyl acetal resin, the proportion of vinyl acetal unit (1) is 50 to 90% by weight, vinyl alcohol unit (2) is 0.1 to 20% by weight and vinyl carboxylate unit (3) is 5 to 20% by weight. Each of these is easy to obtain.

  Specific examples of the polyvinyl acetal resin containing the repeating units (1) to (3) include, for example, polyvinyl formal (R1 = hydrogen atom in the vinyl acetal unit (1), R2 = methyl group in the vinyl carboxylate unit (3). ), Polyvinyl acetoacetal (R1 = vinyl group in vinyl acetal unit (1), R2 = methyl group in vinyl carboxylate unit (3)), polyvinyl propylal (R1 in vinyl acetal unit (1) = ethyl group, vinylcarboxyl) R2 = methyl group in the rate unit (3), polyvinyl butyral (R1 = propyl group in the vinyl acetal unit (1), R2 = methyl group in the vinyl carboxylate unit (3)) and the like. Among these, polyvinyl formal is excellent in heat resistance and is often used for an adhesive for assembling a braking member, and polyvinyl butyral is often used for a copper-clad laminate for printed wiring. Polyvinyl formal is excellent in heat resistance, but has low solubility in organic solvents. Therefore, the adhesive of the present invention can obtain an adhesive in which polyvinyl formal is sufficiently dissolved even when polyvinyl formal is used, and is particularly suitable as an adhesive for assembling a braking member.

  The content of the vinyl alcohol unit (2) in the polyvinyl acetal resin is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and particularly preferably 1 to 7% by weight. If the content of the vinyl alcohol unit (2) is less than 0.1% by weight, the adhesiveness of the polyvinyl acetal resin may be lowered. On the other hand, if it exceeds 20% by weight, the nonvolatile content of the adhesive may be too low. By the way, the content of the vinyl alcohol unit (2) in the polyvinyl acetal resin depends on the kind of the polyvinyl acetal resin and the production method thereof, and is, for example, about 10 to 20% by weight for polyvinyl butyral and about 5% by weight for polyvinyl formal. Polyvinyl formal is preferred. Of course, other polyvinyl acetal resins can be suitably used in the same manner as polyvinyl formal if the content of the vinyl alcohol unit (2) can be adjusted within the above range.

  In the polyvinyl acetal resin according to the present invention, the content of the vinyl acetal unit (1) is preferably selected from the range of preferably 50 to 99% by weight, more preferably 60 to 95% by weight, and particularly preferably 75 to 95% by weight. Is done.

  The molecular weight of the polyvinyl acetal resin depends on the molecular weight of the raw material polyvinyl alcohol, and is preferably from 50 to 5,000, more preferably from 100 to 4,000, particularly preferably when expressed by the number average degree of polymerization of the raw material vinyl alcohol. 300-3,000. If the molecular weight of the polyvinyl acetal resin is too small, the adhesiveness of the adhesive may be impaired. The weight average molecular weight (in terms of polystyrene) is preferably 10,000 to 500,000, more preferably 20,000 to 300,000, and particularly preferably 30,000 to 200,000. As the molecular weight increases, the solubility in an organic solvent decreases. Particularly, polyvinyl formal having a high molecular weight is difficult to dissolve in an organic solvent, particularly a solvent having no environmental problem and having a low boiling point. However, the adhesive of the present invention can be sufficiently used even if it is a polyvinyl formal having a weight average molecular weight of 50,000 or more, more preferably 80,000 or more.

  As the (B) phenol resin used in the present invention, either a novolac type phenol resin or a resol type phenol resin can be used. Moreover, any shape of liquid, solid, and powder can be used.

  Of the phenol resins exemplified above, a resol type phenol resin is desirable from the viewpoints of adhesiveness, particularly hot bond strength and normal bond strength after heat aging.

  (B) The amount of the phenol resin used is preferably 30 to 300 parts by weight, more preferably 150 to 250 parts by weight, based on 100 parts by weight of the (A) polyvinyl acetal resin. If the phenol resin is less than 30 parts by weight, sufficient heat resistance cannot be obtained, and if it exceeds 300 parts by weight, sufficient flexibility cannot be obtained and impact resistance is lowered.

  The carbonic acid ester (C) used in the present invention has a structure in which carbonic acid and alcohol are esterified, has low irritation, toxicity and bad odor, and has a very low environmental impact. In addition, the flammability is very low as compared with a carboxylic acid ester solvent having a similar structure, and it is safer. For example, the flash point of diethyl carbonate is 31 ° C., which is higher than room temperature, compared to the flash point of ethyl acetate −4 ° C.

  For this reason, the phenol resin / polyvinyl acetal resin adhesive of the present invention can be operated more safely than the conventionally used phenol resin / polyvinyl acetal resin adhesive.

  The carbonate ester includes a chain carbonate ester in which two substituents are not linked to each other and a cyclic carbonate ester having a structure in which two substituents are linked to each other.

  Examples of chain carbonates include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl n-propyl carbonate, ethyl n-propyl carbonate, di-n-propyl carbonate, methyl iso-propyl carbonate, ethyl iso-propyl carbonate, diiso- Propyl carbonate, butyl methyl carbonate, butyl ethyl carbonate, butyl n-propyl carbonate, dibutyl carbonate, methyl-2,2,2-trifluoroethyl carbonate, ethyl-2,2,2-trifluoroethyl carbonate, di (2, 2,2-trifluoroethyl) carbonate, methyl-3,3,3,2,2-pentafluoropropyl carbonate, ethyl-3,3,3,2,2-pentafluoropropyl Boneto, propyl -3,3,3,2,2- pentafluoro-propyl carbonate, and di (3,3,3,2,2-pentafluoro-propyl) carbonate.

  Examples of cyclic carbonates include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentene carbonate, and 2,3-pentene carbonate. 1,2-hexene carbonate, 2,3-hexene carbonate, 3,4-hexene carbonate, n-butyl ethylene carbonate, n-hexyl ethylene carbonate, cyclohexyl ethylene carbonate, fluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,2-difluoroethylene carbonate, trifluoromethyl ethylene carbonate, fluoromethyl ethylene carbonate, difluoromethyl ethylene carbonate, chloroethylene car Sulfonate and the like.

  Of the carbonates exemplified above, carbonates having a small molecular weight are desirable from the viewpoints of the solubility of the phenol resin / polyvinyl acetal resin and the viscosity of the adhesive. Examples of such carbonates include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl n-propyl carbonate, ethyl n-propyl carbonate, di-n. -Propyl carbonate, methyl iso-propyl carbonate, ethyl iso-propyl carbonate, diiso-propyl carbonate, di-n-propyl carbonate, etc. are desirable, ethylene carbonate, 1,2-propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl Carbonate and the like are more desirable, and dimethyl carbonate and diethyl carbonate are most desirable.

  The chain carbonate ester and the cyclic carbonate ester may be used alone or as a mixture thereof. In order to further enhance the solubility of the phenol resin / polyvinyl acetal resin, the molecular weight or chemical structure of the phenol resin / polyvinyl acetal resin is limited to a specific one, or the phenol resin / polyvinyl acetal resin is heated by being dissolved. Can be dissolved. Here, increasing the solubility of the phenol resin / polyvinyl acetal resin means, for example, that the phenol resin / polyvinyl acetal resin is dissolved at a higher concentration, can be dissolved regardless of the type of the polyvinyl acetal resin, and needs to be heated at the time of dissolution. This means that the phenol resin / polyvinyl acetal resin does not precipitate even when the adhesive temperature decreases to room temperature or lower after dissolution.

  The water content of the carbonate is 200 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less. If it exists in this range, the moisture content of a phenol resin and a polyvinyl acetal resin will be restrained low, and a preferable adhesive agent will be obtained.

  (C) The amount of carbonic acid ester used is preferably 100 to 500 parts by weight, more preferably 200 to 400 parts by weight, based on 100 parts by weight of (A) polyvinyl acetal resin. When the carbonate ester is less than 100 parts by weight, the viscosity of the adhesive is increased and the coating property is lowered. In addition, the storage stability of the adhesive also decreases. If the amount exceeds 400 parts by weight, the non-volatile content decreases, so it takes time to dry and the adhesive layer becomes thin, so that sufficient adhesive strength cannot be obtained.

  In the present invention, methanol is used together with carbonate as a solvent. Other alcohols such as ethanol and butanol are inferior in solubility of phenol resin and polyvinyl acetal resin. In particular, it is difficult to dissolve a phenol resin / polyvinyl formal resin having a weight average molecular weight of 50,000 or more. (D) The amount of methanol used is preferably 10 to 200 parts by weight, more preferably 50 to 100 parts by weight, based on 100 parts by weight of (A) polyvinyl acetal resin. If it is less than 10 weight part, it will become difficult to melt | dissolve a phenol resin and polyvinyl acetal resin uniformly. If it exceeds 200 parts by weight, the non-volatile content decreases, so it takes time to dry and the adhesive layer becomes thin, so that sufficient adhesive strength cannot be obtained.

  In addition to the above-described components, a coupling agent, a filler, a diluent, a colorant, and the like may be added to the adhesive of the present invention as necessary within a range that does not impair the performance of the adhesive. Examples of the coupling agent include silane coupling agents such as chloropropyltrimethoxysilane and vinyltrichlorosilane, and titanium coupling agents such as isopropyltriisostearoyl titanate and isopropyltrilauryl myristyl titanate. Examples of the filler include carbon black, titanium oxide, talc, clay, magnesium oxide, calcium carbonate, mica and the like. Examples of the diluent include alcohol solvents other than methanol such as ethanol and isopropyl alcohol, butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, pentane and hexane. Examples of the colorant include titanium oxide, chromium oxide, and zinc oxide.

  The method for producing the adhesive of the present invention is not particularly limited, and (A) a polyvinyl acetal resin, (B) a phenol resin, (C) a carbonic ester, (D) a method of mixing methanol and (A There is a method of adding (D) methanol after dissolving a polyvinyl acetal resin and (B) phenol resin in (C) carbonate ester.

  For mixing, a known mixer with a stirrer can be used. When the viscosity is high, a high viscosity mixer such as a planetary mixer or a kneader can be used. Moreover, although mixing temperature is not specifically limited, Usually, it selects suitably from the range of 20-30 degreeC.

When the adhesive of the present invention is used for bonding metal to metal, metal to resin plate, or metal to friction material, the hot strength at 200 ° C. is maintained, and sufficient adhesive strength after heat aging. Have Examples of the adherend bonded by the adhesive of the present invention include metals, resin plates, and friction materials, and combinations of metals and metals, metal and resin plates and friction materials, resin plates and resin plates, friction materials and friction materials. Among them, a combination of a metal and a friction material is preferable. Examples of the metal include copper, steel, gray cast iron, addition of Ni and Cr, and high carbonized steel. Moreover, a phenol resin board is mentioned as an example of a resin board. Examples of friction materials include phenolic resin, binder, organic materials such as rubber, filler, metallic materials such as copper, brass, zinc, graphite, MoS ₂ , BaSO ₄ , CaCO ₃ , SiO ₂ , MgO, etc. The friction material which added the inorganic substance is mentioned.

  In particular, in the case of an automobile, it is preferable that the metal is a brake pressure plate and the friction material is a lining in which carbon fibers are hardened with a phenol binder, and the adhesive of the present invention is sandwiched between the pressure plate and the lining. . A method for assembling a braking member using the adhesive of the present invention is as follows. The adhesive of the present invention is applied to one or both surfaces of the adherend, and the adhesive is sandwiched between the two adherends. This can be done by heating at 200 ° C. for 0.2 to 3 hours to cure.

  The adhesive of the present invention is useful for adhesion of brakes and clutch facings of automobiles, motorcycles, railway vehicles, aircrafts, industrial machines, etc., in particular, metal pressure plates of automobile disk brakes and drum brakes, and linings which are friction materials. It is. FIG. 1 shows an example of a disc brake for an automobile, and a brake using the adhesive of the present invention will be described.

  FIG. 1 is a cross-sectional view of a disc brake 1 cut parallel to the wheel axis. In FIG. 1, a disc brake 1 is provided on a metal shaft 10 provided in parallel to a wheel on a wheel shaft 11, and is provided on a plane on both sides of the disc 10 so as to be parallel to the plane of the disc 10. It has a brake part which consists of a pair of linings 12 and 12 'which have a contact surface, and pressure plates 14 and 14' which hold those linings 12 and 12 '. The brake part can be moved in a direction perpendicular to the metal disk 10 via the pistons 15 and 15 'by the pressure of the hydraulic device. The lining 12 and the pressure plate 14 or the lining 12 ′ and the pressure plate 14 ′ are bonded together by the adhesives 13 and 13 ′ of the present invention.

The disk 10 is a disk made of metal such as steel, gray cast iron, addition of Ni or Cr, or high carbonized steel. The disk 10 is arranged so that the disk 10 is perpendicular to the wheel shaft 11. It is fixed to the shaft 11. The linings 12 and 12 ′ are friction materials obtained by adding an organic material such as rubber, a metal such as copper, brass, or zinc as a binder, an inorganic material such as graphite, MoS ₂ , BaSO ₄ , CaCO ₃ , SiO ₂ , or MgO as a binder. It is provided on the vehicle body in pairs with the disk 10 interposed therebetween, and is adhered to the back surface of the surface facing the disk 10 by pressure plates 14 and 14 'and adhesives 13 and 13'.

  The pressure plates 14 and 14 'are made of metal such as gray cast iron and steel, and one end is connected to the brake hydraulic device via the pistons 15 and 15', and the other is the adhesive 13 and 13 'of the present invention. The linings 12 and 12 'are bonded to each other via the.

  Furthermore, as a drum brake, FIG. 2 shows an example of a cross-sectional view of the drum brake 20 in which the wheel is cut perpendicular to the wheel axis. In FIG. 2, the wheel drum 21 is made of metal such as gray cast iron or steel, and the linings 12 and 12 ′ and the pressure plates 14 and 14 ′ are made of the same material as in the case of the disc brake. It is bonded via 13 '. When the brake operation is performed, the pressure plates 14 and 14 'are pushed in the direction of the disk 10 or the drum 21 through the pistons 15 and 15' by the pressure of the hydraulic device, and the lining 12 and the pressure plates 14 and 14 'through the pressure plates 14 and 14'. 12 'contacts the planes on both sides of the rotating disk 10 or the inner surface of the drum 21 to generate frictional resistance, thereby preventing the disk 10 or the drum 21 from rotating and braking the wheel.

  The adhesive composition thus obtained has excellent hot bond strength and normal bond strength after heat aging, and does not use toluene, xylene, dioxane and chlorinated solvents, thus reducing environmental impact and irritation. It is useful as an adhesive for assembling braking members because it has few problems in terms of toxicity, environmental pollution, odor, and flammability and can improve safety.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, it cannot be overemphasized that these Examples are shown by illustration and should not be interpreted limitedly.

  The adhesives of the examples were subjected to the following tests on the adhesives obtained with the compositions shown in Table 1.

(Compatibility test)
About 20 g was put into a 50 ml glass bottle, and the dissolution state after standing at 23 ° C. for 24 hours was visually confirmed.
Evaluation criteria A: Uniformly compatible.
○: A small amount of separation is observed.
Δ: Some significant separation is observed.
X: Separation is observed as a whole.

(Applicability test)
It apply | coated so that the application quantity might be set to 120 g / m < ² > on kraft paper using the bar coater. The coating state at that time was confirmed visually.
Evaluation criteria ○: It is applied evenly and uniformly.
X: It is not apply | coated uniformly and unevenly.

(viscosity)
Based on the test method of 5.4 “Viscosity” of JIS K6833-1, the viscosity of the adhesive composition under 23 ° C. conditions was measured using a BM type rotational viscometer.

(Drying test)
It apply | coated so that the application quantity might be set to 120 g / m < ² > on kraft paper using the bar coater. It was left for 30 minutes in an atmosphere of 50 ° C., and the state of the adhesive was confirmed by finger touch.
Evaluation criteria ○: The adhesive does not adhere to the hand, and there is no stickiness.
Δ: Adhesive does not adhere to hand, but has stickiness
X: Adhesive adheres to the hand.

(Normal bond strength test)
A bar coater was used on two mild steel plates with a width of 25 mm, a length of 100 mm, and a thickness of 1.6 mm, so that the coating amount was 100 g / m ² on the part of the length of 12.5 mm from one end. Apply. After taking an open time at 50 ° C. for 30 minutes, bonding is performed so that the adhesive application portions overlap. While applying a pressing pressure of 10 kgf / cm ² , the test piece was cured by curing at 200 ° C. for 2 hours. The obtained test piece is allowed to stand at 23 ° C. for 7 days, and then the tensile shear bond strength is measured in an atmosphere at 23 ° C. (tensile speed: 2.5 mm / min).

(Hot bond strength test)
A test piece obtained by the same method as in the normal state adhesive strength test is measured for tensile shear adhesive strength in an atmosphere at 200 ° C. (tensile speed: 2.5 mm / min).

(Normal bond strength test after heat aging)
A test piece prepared in the same manner as the normal bond strength is heat-aged at 200 ° C. for 7 days, and then the tensile shear bond strength is measured in a 23 ° C. atmosphere (tensile speed: 2.5 mm / min).

  In Example 1, (A) polyvinyl formal resin was used as the polyvinyl acetal resin, (B) resol type phenol resin was used as the phenol resin, and (C) dimethyl carbonate was used as the carbonic acid ester. The compatibility, applicability, viscosity, drying property, and adhesive strength of the adhesive are shown in Table 1.

* 1: Polyvinyl formal resin, trade name: Vinylec E (number average molecular weight 115000) manufactured by Chisso Corporation
* 2: Resole type phenolic resin, trade name: Sumilite Resin PR51406, manufactured by Sumitomo Bakelite Co., Ltd.

  In Example 2, diethyl carbonate was used as the carbonic acid ester (C). From a comparison between Example 1 and Example 2, it can be seen that Example 1 is excellent in compatibility and drying properties and excellent in adhesive strength.

(Comparative Examples 1 and 2)
In Comparative Example 1, methanol was not used and only dimethyl carbonate was used. In Comparative Example 2, ethanol was used instead of methanol. In Comparative Example 1, the phenol resin / polyvinyl acetal resin was not dissolved. In Comparative Example 2, the phenol resin / polyvinyl acetal resin was dissolved, but the compatibility was inferior to that of Example 1 or Example 2.

(Comparative Examples 3 and 4)
In Comparative Example 3, benzyl alcohol was used in place of the carbonate ester. In Comparative Example 4, benzyl alcohol and methanol were used in combination. This solvent dissolves the phenol resin / polyvinyl acetal resin and has been found during the study of a solvent having a small environmental problem, and even benzyl alcohol alone dissolves the phenol resin / polyvinyl acetal resin. However, it can be seen that by using benzyl alcohol, the compatibility is sufficient, but the viscosity is high and the applicability is lowered. Moreover, it turns out that drying time becomes long and drying property falls. Moreover, it turns out that the direction of Example 1 is excellent in adhesive strength rather than the comparative examples 3 and 4. FIG.

(Comparative Examples 5, 6, and 7)
In Comparative Example 5, a mixed solvent of toluene and ethanol, which is used in the patent literature, was used as a solvent for the phenol resin / polyvinyl acetal resin. Compared with Example 1 and Example 2, the compatibility was insufficient. In Comparative Example 6, a mixed solvent of toluene and ethanol was used. In this case, the compatibility was improved as compared with Comparative Example 5, but the compatibility in Example 1 was superior. Comparative Example 6 The adhesive strength was evaluated using an adhesive, but the adhesive strength in the case of Example 1 was superior. In Example 7, only toluene was used, but the phenol resin / polyvinyl acetal resin could not be dissolved.

(Comparative Examples 8 to 13)
In Comparative Examples 8 to 13, environmental problems were small, and a solvent having an appropriate boiling point or a mixed solvent of this solvent and methanol was used. As is apparent from the table, these solvents could not dissolve the phenol resin / polyvinyl acetal resin.

  The adhesive of the present invention uses a solvent having a small environmental problem, is excellent in adhesive strength at a high temperature of 200 ° C., and is excellent in adhesive strength after heat aging. The adhesive of the present invention is useful not only for bonding a pressure plate of a brake for a vehicle such as a disc brake or a drum brake and a friction material, but also for assembling a clutch facing or a railcar brake.

1 Disc brake 10 Disc 11 Wheel shaft 12, 12 'Lining 13, 13' Adhesive 14, 14 'Pressure plate 15, 15' of the present invention Piston 20 Drum brake 21 Drum

Claims (9)

(A) 100 parts by weight of polyvinyl formal resin ,
(B) 30 to 300 parts by weight of phenol resin,
(C) 100 to 500 parts by weight of carbonate ester, and (D) phenol resin, polyvinyl acetal resin based adhesive you containing 10 to 200 parts by weight of methanol. (A) the weight average molecular weight of the polyvinyl formal resin is Ru Oh on 50,000 or more, a phenol resin, polyvinyl acetal resin based adhesives 請 Motomeko 1 wherein. The phenol resin (B) is Ru resole phenolic resin der,請 Motomeko 1 or 2 phenolic resin, polyvinyl acetal resin based adhesive according. Wherein (C) carbonate is ethylene carbonate, 1,2-propylene carbonate, dimethyl carbonate, Ru least 1 Tanedea selected from ethyl methyl carbonate and diethyl carbonate, according to any one 請 Motomeko 1-3 phenol Resin / polyvinyl acetal resin adhesive. Wherein (C) carbonic ester Ru dimethyl carbonate der, phenol resins, polyvinyl acetal resin based adhesives 請 Motomeko 4 wherein. You the assembly of the braking member and the applications, a phenol resin, polyvinyl acetal resin adhesive according to any one of 請 Motomeko 1-5. The adhesive body by which the metal and any one of a metal, a resin board, or a friction material are adhere | attached with the phenol resin and polyvinyl formal resin-type adhesive agent in any one of Claims 1-6. A braking member in which a metal and a friction material are bonded by the phenol resin / polyvinyl formal resin adhesive according to any one of claims 1 to 6. Ru assemble the brake member by using a phenolic resin Polyvinyl acetal resin based adhesive according to claim 1, method of assembling Braking members.

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