JP2001247836A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition which is used in producing a metal panel from a mirror-like metal sheet 1 polished up for designing and can give a metal panel the adhesion distortion of which can not be confirmed. SOLUTION: This adhesive composition satisfies the condition represented by equation (1): Y<=860X-0.6 [wherein X (%) is the cure shrinkage of the adhesive composition; and Y (MPa) is the storage modulus of a cured item of the composition] at 20-25 deg.C and contains a flame retardant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant adhesive composition, and more particularly to a flame-retardant cold-setting adhesive composition for reinforcing adhesion of metal panels.

[0002]

2. Description of the Related Art A metal panel is obtained by bonding a thin metal plate and a reinforcing plate, and is used for interior materials of buildings, for example, partition boards, doors, elevators, and storages. The rigidity does not appear at the center of the thin metal plate alone. Therefore, a reinforcing plate is joined to the center to provide the metal panel with rigidity. Although there are various shapes of the metal panel, for example, as shown in FIG. 1, a metal plate 1 and a reinforcing plate 2 are bonded. As the metal thin plate and the reinforcing plate, those obtained by bending the peripheral edge of the metal thin plate and the reinforcing plate are used in order to have rigidity.

[0003] Mirror-polished metal sheets are used in high-end hotels and the like because they are beautiful in appearance and are preferable in terms of design.

[0004] As an adhesive composition used in the production of a metal panel, it is required to use a room-temperature fast-curing adhesive composition which cures in a short time at normal temperature in terms of labor saving, resource saving and energy saving. Have been. Conventionally, room-temperature fast-curing adhesive compositions include two-part fast-curing epoxy adhesive compositions, anaerobic adhesive compositions, instantaneous adhesive compositions, and second-generation acrylic adhesive compositions (SGA ) It has been known.

[0005] A two-part type fast-curing epoxy adhesive composition comprises:
It is an epoxy adhesive composition which measures and mixes a main agent and a curing agent, applies the mixture to an adherend, and cures by a reaction between the main agent and the curing agent. However, the two-part fast-curing epoxy adhesive composition has a drawback in that the peel strength and the impact strength are weak.

The anaerobic adhesive composition is cured by pressing the adhesive composition between adherends to block air. However, the anaerobic adhesive composition has a drawback that, when a part of the adhesive composition comes out of the adherend during the pressure bonding, the exposed part comes into contact with air and thus does not cure. Further, it has a disadvantage that it does not cure even when the clearance between adherends is large, and has not been used for reinforcing adhesion of metal panels.

The instant adhesive composition usually contains cyanoacrylate as a main component and has excellent workability. However, it has a drawback that peel strength and impact strength are low, and has not been used for reinforcing adhesion of metal panels or the like because of poor moisture resistance and water resistance.

Although SGA (second generation acrylic adhesive composition) is a two-part type, it does not require accurate metering of the two parts, and may be incompletely weighed or mixed, or even only in contact with the two parts. It is widely used because it is hardened at room temperature for several minutes or tens of minutes, is excellent in workability, has high peel strength and impact strength, and has good hardening of the exposed portion.

However, when SGA is used for bonding metals, the adhesive strength to the metal is so high that when the adhesive composition cures and shrinks during curing, the metal of the adherend suffers from adhesive distortion. As a result, the aesthetic appearance on the metal panel surface is impaired, and the metal panel cannot be used for reinforcing adhesion.

[0010] Therefore, when using a mirror-finished metal panel polished for a design, a metal panel is manufactured by bonding a metal thin plate and a reinforcing plate in advance, and the metal panel surface is polished for the design. A method of further laminating the raised metal sheet with a rubber-based adhesive composition or the like has been performed.

[0011]

However, this method has a problem that the production of the metal panel is very costly and the weight of the metal panel is heavy.

[0012] In order to solve these problems, the present invention provides polishing for design by setting the curing shrinkage of the adhesive composition and the storage elastic modulus of the cured product of the adhesive composition within specific ranges. The present inventors have found that a metal panel in which adhesion distortion cannot be confirmed can be obtained in a metal panel using the raised mirror-finished metal thin plate, and have completed the present invention.

[0013]

That is, according to the present invention, the curing shrinkage of the adhesive composition is represented by X (unit:%), and the storage elastic modulus of the cured product of the adhesive composition is represented by Y (unit: MPa). And an adhesive composition that satisfies the condition of the following formula (1) at 20 to 25 ° C. and contains a flame retardant, and a formula (1) Y ≦ 860X− ^0.6 adhesive When the curing shrinkage of the composition is X (unit:%) and the storage modulus of the cured product of the adhesive composition is Y (unit: MPa), at 20 to 25 ° C., the following formula (2) is obtained. An adhesive composition that satisfies the conditions, wherein the adhesive composition has the following formula: (2) Y ≦ 44X ^{−1.0 The} fixing time is 12 minutes or more, and the adhesive composition is a cold-setting adhesive composition. The adhesive composition, wherein the adhesive composition is an acrylic adhesive composition.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The adhesive composition of the present invention has a curing shrinkage of X
(Unit:%), and when the storage elastic modulus of the cured product of the adhesive composition is Y (unit: MPa), at 20 to 25 ° C., an adhesive composition that satisfies the following formula (1) is used. is there. Formula (1) Y ≦ 860X ^−0.6

Further, in the present invention, the formula (2) is preferably Y ≦ 44X− ^1.0 .

Unless Y satisfies the above equation, adhesive distortion appears on the metal panel, which is not preferable.

X is preferably 0.01 to 12, more preferably 0.01 to 12.
To 8 are more preferable. If it is less than 0.01, it may be difficult to mix the adhesive composition. If it exceeds 12, the storage modulus must be extremely small, and the adhesive strength may be low.

The lower limit of Y is preferably 1 MPa, and 5 MPa
a is more preferable. If it is less than 1 MPa, the adhesive composition may be too soft and the adhesiveness may be reduced.

In the adhesive composition of the present invention, the adhesive distortion cannot be eliminated only by a small curing shrinkage, and an adhesive having a high curing speed cannot be used for a large metal panel which requires a long time for application. There is a possibility that internal stress causing distortion may easily occur. In order to solve this problem, the fixing time of the adhesive composition of the present invention is preferably 12 minutes or more, more preferably 12 minutes to 1440 minutes, and 12 minutes to 72 minutes.
0 minutes is most preferred. If the time is less than 12 minutes, when manufacturing a large metal panel, there is a problem that the adhesive composition hardens before the adhesive composition is applied to the entire application surface, and an internal stress that causes an adhesive distortion is generated. May easily occur. If it exceeds 1440 minutes, it takes time to manufacture the metal panel, and there is a possibility that productivity may be affected.

Examples of the flame retardant of the present invention include conventional flame retardants such as halogen-based flame retardants, phosphorus-based flame retardants, organic acid metal salt-based flame retardants and inorganic flame retardants.

Examples of the halogen-based flame retardant include tetrabromobisphenol A, decabromodiphenyl oxide,
Hexabromocyclododecane, octabromodiphenyl oxide, bistribromophenoxyethane, tribromophenol, ethylenebistetrabromophthalimide, tetrabromobisphenol A polycarbonate oligomer, brominated polystyrene, tetrabromobisphenol A epoxy oligomer / polymer, decabromodiphenylethane, Such as polydibromophenyl oxide, hexabromobenzene, tetradecabromodiphenoxyoxybenzene, brominated epoxy oligomer, bis (tetrabromophthalimide) ethane, bis (tribromophenoxy) ethane, tetrabromophthalic anhydride and tetrabromo-p-cresol; Brominated flame retardants, such as chlorinated paraffin and chlorine-based flame retardants such as perchlorocyclopentadecane.

Examples of the phosphorus-based flame retardants include resorcinyl diphenyl phosphate, hydroquinonyl diphenyl phosphate, phenyl nonyl phenyl hydroquinonyl phosphate, triphenyl phosphate, phenyl dinonyl phenyl phosphate, tetraphenyl resorcinol diphosphate, and tetracresyl bisphenol. A
Phosphate ester flame retardants such as diphosphate and tris (nonylphenyl) phosphate, diphenyl-4-hydroxy-2,3,5,6-tetrabromobenzylphosphonate, dimethyl-4-hydroxy-3,5-dibromo Halogen-containing phosphoric acid (or phosphonic acid) ester flame retardants such as benzylphosphonate and diphenyl-4-hydroxy-3,5-dibromobenzylphosphonate; polyphosphates such as polyphosphoric acid and ammonium polyphosphate; and red Phosphorus and the like. Among these,
From the viewpoint of dispersibility in an adhesive and flame retardancy, a phosphate ester-based flame retardant and / or polyphosphoric acid are preferable, and polyphosphoric acid is more preferable.

Examples of the organic metal salt-based flame retardants include metal salts of organic sulfonic acids, metal salts of carboxylic acids, and metal salts of aromatic sulfonimides.

Examples of the inorganic flame retardant include antimony trioxide, aluminum hydroxide, guanidine nitride, antimony pentoxide, magnesium hydroxide, zinc borate, zinc, zinc oxide and zirconium compounds. Among these, aluminum hydroxide is preferred, in which the temperature of release of contained water of crystallization is close to the thermal decomposition temperature of the adhesive.

These flame retardants may be used alone or in combination of two or more. Among them, a phosphorus-based flame retardant and / or an inorganic flame retardant are preferable in terms of flame retardancy.

The amount of the flame retardant used is 1 to 100 parts by mass of a monomer such as an epoxy, acrylic, urethane, unsaturated polyester or silicone (meth) acrylic.
The amount is preferably from 5 to 150 parts by mass, more preferably from 30 to 80 parts by mass. If the amount is less than 15 parts by mass, the flame retardancy may decrease. If the amount exceeds 150 parts by mass, the modulus of elasticity may increase and the degree of distortion of the metal panel may increase.

The adhesive composition of the present invention is preferably a cold-setting adhesive composition from the viewpoint that thermal stress is not generated due to a difference in linear expansion coefficient between the adhesive composition and the adherend.

The cold-setting adhesive composition of the present invention includes epoxy-based, acrylic-based, urethane-based, unsaturated polyester-based, and silicone-based adhesive compositions. The curing rate is high and the degreasing treatment before bonding is easy. In this respect, acrylic is preferable.

The acrylic adhesive composition is a reactive acrylic adhesive composition containing a (meth) acrylic monomer and being polymerized and cured. Examples of (meth) acrylic monomers include the following.

The general formula ZOR₁ A monomer represented by Wherein Z is (meth) acryloyl
Group, CH_Two= CHCOOCH_Two-CH (OH) CH_Two-Group or CH _Two= C (CH_Three)
COOCH_Two-CH (OH) CH_Two-Represents a group, R₁Has 1 to 20 carbon atoms
Alkyl groups, cycloalkyl groups, benzyl groups,
Nyl, tetrahydrofurfuryl, glycidyl, di
Cyclopentyl group, dicyclopentenyl group or (meth)
Shows an acryloyl group.

Examples of such a monomer include methyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and dicyclopentyl (meth) acrylate. , Dicyclopentenyl (meth) acrylate,
Glycerol (meth) acrylate or glycerol di (meth) acrylate is exemplified.

A monomer represented by the general formula Z—O— (R ₂ O) _p —R ₁ . In the formula, Z and R ₁ are as described above. R ₂ is _{-C 2 H 4 -, - C} 3 H 6 -, - CH 2 CH (CH 3) -, - C 4
H ₈ - or -C ₆ H ₁₂ - indicates, p is an integer of 1 to 25.

Examples of such a monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, ethoxyethyl (meth) acrylate, polyethylene glycol (meth) acrylate, and phenoxyethyl (meth). Acrylate,
Examples thereof include dicyclopentenyloxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, tripropylene glycol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate.

General formula

Embedded image A monomer represented by In the formula, Z and R ₂ are as described above. R ₃ represents hydrogen or an alkyl group having 1 to 4 carbon atoms;
q represents an integer of 0 to 8.

Examples of such a monomer include, for example, 2,2
-Bis (4- (meth) acryloxyphenyl) propane, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxydiethoxyphenyl) propane And 2,2-bis (4- (meth) acryloxypropoxyphenyl) propane or 2,2-bis (4- (meth) acryloxytetraethoxyphenyl) propane.

(Meth) acrylic acid esters of polyhydric alcohols not included in the monomers described in or above.

Examples of such a monomer include trimethylolpropane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate and dipentaerythritol hexa (meth) acrylate. Can be

A urethane prepolymer having a (meth) acryloyloxy group. Such a monomer can be obtained, for example, by reacting a (meth) acrylate having a hydroxyl group, an organic polyisocyanate, and a polyhydric alcohol.

The (meth) acrylate having a hydroxyl group includes, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate or hydroxybutyl (meth) acrylate.

Examples of the organic polyisocyanate include toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

Examples of the polyhydric alcohol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyester polyol.

An acidic phosphoric acid compound represented by the following general formula (I):

Embedded image In the formula, R is a CH ₂ CRCR ₄ CO (OR ₅ ) _m — group (where R ₄ is a hydrogen or methyl group, R ₅ is —C ₂ H ₄ —, —C ₃ H ₆ —, —CH ₂ CH (CH
_{3) -, - C 4 H} 8 -, - C 6 H 12 - or

Embedded image And m represents an integer of 1 to 10. ), And n is 1
Or an integer of 2.

Examples of the acidic phosphoric acid compound represented by the general formula (I) include acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate and bis (2- (meth) acryloyloxyethyl) phospho. Fate and the like.

In order to obtain a cold-setting adhesive composition,
In the case of an acrylic adhesive composition, a polymerization initiator such as an organic peroxide and a reducing agent for decomposing the same may be used in combination with the (meth) acrylic monomer.

Examples of the organic peroxide include cumene hydroperoxide.

The amount of the organic peroxide to be used is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, per 100 parts by mass of the (meth) acrylic monomer. If the amount is less than 0.1 part by mass, curing failure may occur. If the amount exceeds 10 parts by mass, storage stability may be impaired.

Examples of the reducing agent include ethylene thiourea and vanadyl acetylacetone.

The amount of the reducing agent used is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the (meth) acrylic monomer. If the amount is less than 0.05 part by mass, poor curing may occur, and if it exceeds 10 parts by mass, the storage stability may be impaired.

Further, in the case of an acrylic adhesive composition, a diene rubber such as acrylonitrile-butadiene rubber (NBR) or an acrylonitrile-butadiene-methacrylic acid copolymer is used to impart toughness to the adhesive composition. Polymer, butadiene-styrene-methyl methacrylate copolymer (MBS) and butadiene-styrene-acrylonitrile-methyl methacrylate copolymer (MBAS)
And the like. Among them, diene rubber is preferable from the viewpoint of adhesiveness.

The amount of the diene rubber or synthetic polymer used is
5 to 5 with respect to 100 parts by mass of the (meth) acrylic monomer
0 parts by mass is preferable, and 8 to 30 parts by mass is more preferable.
If the amount is less than 5 parts by mass, the cured adhesive composition may not be strong, and if it exceeds 50 parts by mass, the viscosity may be too high.

Further, in the case of an acrylic adhesive composition, a plasticizer can be used from the viewpoint of imparting flexibility. Examples of the plasticizer include dioctyl phthalate and dioctyl adipate.

The amount of the plasticizer used is preferably 50 parts by mass or less based on 100 parts by mass of the (meth) acrylic monomer.

Further, in the case of an acrylic adhesive composition, an inorganic filler can be used from the viewpoint of reducing the curing shrinkage. Among the inorganic fillers, silica and / or talc, which have good dispersibility in an acrylic adhesive, are preferable.

The amount of the inorganic filler used is preferably 150 parts by mass or less based on 100 parts by mass of the (meth) acrylic monomer. If it exceeds 150 parts by mass, the viscosity may be too high.

Among the room temperature-curable acrylic adhesive compositions, from the viewpoint of workability, the A agent contains at least an organic peroxide and the B agent contains at least a reducing agent. The two-part acrylic adhesive composition comprising the agent and the agent B is more preferable.

The adherend to which the adhesive composition of the present invention is used is preferably a metal. In particular, when used in the production of a mirror-finished metal panel polished for a design, excellent adhesion distortion is not visually observed. Has the effect.

When the adhesive composition of the present invention is used for reinforcing adhesion of a metal panel, the bonding method is as follows.
1 and the joining surface of the reinforcing plate 2 are adhered as shown in FIG.
In the case of a two-part acrylic adhesive composition, one of the metal sheet and the reinforcing sheet may be overcoated with the agent A and the agent B and mixed, and the metal sheet and the reinforcing sheet may be bonded together.
The agent B and the reinforcing agent may be separately applied to the reinforcing agent and the reinforcing agent, and the thin metal plate and the reinforcing plate may be bonded to each other.

Examples of the material of the metal sheet polished like a mirror for design use include stainless steel and brass. The thickness of the metal sheet is preferably 0.1 to 3.2 mm, and 0.5 to 2.0 mm.
mm is more preferable. If it is less than 0.1 mm, it may be difficult to bond the film without adhesion distortion, and 3.2.
If it exceeds mm, the metal thin plate becomes heavy, and the weight of the metal panel may not be reduced.

[0060]

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

Experimental Example 1 The adhesive compositions shown in Table 1 were prepared and evaluated by the following methods. Table 1 shows the results. The adhesive composition used was a mixture of the first agent and the second agent at a mixing ratio of 1: 1.

[Materials Used] Urethane acrylate DET-1B: manufactured by Light Chemical Co., Ltd.

[Evaluation Method] (Measurement of Curing Shrinkage) The specific gravity of each adhesive composition was determined according to JIS.
Determined from 3.1 (1) of K 7232, the specific gravity of the cured product of each adhesive composition is determined according to JIS K 7232 3.2.
The curing shrinkage was determined from the following equation, obtained from (1). (Curing shrinkage) = (cured body specific gravity−liquid specific gravity) / (cured body specific gravity) × 100 (%) (measurement of storage elastic modulus) Each adhesive composition was cured into a sheet having a thickness of 1 mm. Viscoelasticity measurement device (Tension Module DM manufactured by Seiko Denshi Kogyo Co., Ltd.)
S210), and the storage modulus at 23 ° C. was determined. (Fixing time) The time at which the tensile shear strength adhesive strength becomes 0.1 MPa or more after bonding according to the method described in JIS K 6850, "Measurement method of tensile shear strength adhesive strength of adhesive" was defined as the fixing time. The adhesion test piece was iron (SPCC 100 × 25 ×
1.6 mmt). (Measurement of Adhesion Strain) A metal thin plate 1 made of a stainless steel plate (SUS304, 1.5 mmt) whose surface is mirror-finished is bent into the shape shown in FIG. 1 so that the mirror-finished surface becomes the surface (lower in FIG. 1). Created by processing. In addition, electrogalvanized phosphoric acid treated steel sheet (SECC-P, 1.6 mmt)
Was formed by bending into a shape shown in FIG. As shown in FIG. 1, the back surface of the metal thin plate 1 and the reinforcing plate 2 were adhered to each other with an adhesive composition as shown in FIG. 1 and then cured at room temperature for one week to produce a metal panel. Adhesion distortion was determined by leaning the metal panel, and visually determining the presence or absence of adhesion distortion from a position 5 m away from the mirror-finished surface of the metal panel.
The judgment is as follows. ：: Adhesion distortion is not recognized. Δ: Slight adhesive distortion is observed. X: There is clear adhesion distortion. (Flame retardancy) Thickness 1 / according to UL-94 vertical combustion test method
A cured product of each of the 8-inch adhesive compositions was prepared, and the flammability was evaluated.

[0064]

[Table 1]

Experimental Example 2 The adhesive compositions shown in Table 2 were prepared and evaluated. Table 2 shows the results.

[Materials] Epoxy adhesive 45/15: Ecobond 45 / Ecobond 15 (Grace Japan Co., Ltd.) Epoxy adhesive DP-60 Clear: Sumitomo 3M Co., Ltd.

[0067]

[Table 2]

EXPERIMENTAL EXAMPLE 3 Using the adhesive composition having the composition of 1-1, Table 3
The adhesion distortion and workability were evaluated using a stainless steel plate having a mirror-finished surface with the thickness shown in FIG. Table 3 shows the results.

[Evaluation method] (Measurement of workability) A case where metal panels were easily manufactured was evaluated as 、,
The case where the metal panel was heavy and its manufacture was not easy was evaluated as x.

[0070]

[Table 3]

Experimental Example 4 The adhesive compositions shown in Table 4 were evaluated. However, Experiment No. 4-1 is Experiment No. The adhesive composition having the composition of No. 1-1 was used in Experiment No. 1-1. 4-2 is Experiment No. A 2-1 blend was used. Table 4 shows the results.

[Evaluation Method] (Measurement of Adhesive Strength) Tensile speed was measured by the method described in JIS K 6850, “Method of measuring tensile shear adhesive strength of adhesive”.
The tensile shear bond strength was measured at mm / min. The adhesion test piece was made of iron coated with rust-preventive oil (SPCC 100 × 25 ×
(1.6 mmt) was wiped with a waste cloth, adhered, and cured at room temperature for 7 days.

[0073]

[Table 4]

[0074]

According to the present invention, the use of a flame-retardant adhesive composition having a specific storage elastic modulus and a curing shrinkage has an effect of preventing the occurrence of adhesive distortion on a metal panel. Furthermore, by using an adhesive composition having a specific curing time, there is an effect that it can be used for manufacturing a huge metal panel. Also, according to the present invention, when a metal panel is manufactured by bonding a metal sheet polished to a mirror surface for a design and a reinforcing plate, in addition to the metal sheet and the reinforcing plate, in order to maintain the design property of the metal sheet, Since there is no need to use a metal plate, there is an effect that the cost is low and the weight of the panel is light.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a metal panel that has been reinforced and bonded.

[Explanation of symbols]

 1 Thin metal plate 2 Reinforcement plate

Claims (5)

[Claims] The curing shrinkage of the adhesive composition is represented by X (unit:
%), And when the storage elastic modulus of the cured product of the adhesive composition is Y (unit: MPa), at 20 to 25 ° C., the condition of the following formula (1) is satisfied, and the flame retardant is used. An adhesive composition containing the composition. Formula (1) Y ≦ 860X ^−0.6 2. The curing shrinkage of the adhesive composition is represented by X (unit:
%), And the storage elastic modulus of the cured product of the adhesive composition is represented by Y (unit: MPa), at 20 to 25 ° C., an adhesive composition that satisfies the condition of the following formula (2). Formula (2) Y ≦ 44X ^−1.0 3. The adhesive composition according to claim 1, wherein the fixing time is 12 minutes or more. 4. The adhesive composition according to claim 1, wherein the adhesive composition is a cold-setting adhesive composition. 5. The adhesive composition according to claim 1, wherein the adhesive composition is an acrylic adhesive composition.