JPH06852B2 - Adhesion method between urethane elastomer and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a primer composition for urethane elastomer having excellent adhesion to metal.

Urethane elastomers are used for various industrial materials such as belts and solid tires because of their excellent mechanical properties, abrasion resistance, chemical resistance and the like.

[Conventional technology]

Depending on the purpose of the urethane elastomer, it is often used by adhering it to a metal such as a roll.For example, when adhering a thermosetting urethane elastomer represented by adiprene to a metal, Chemlok 218 or Conap 1146C is used.
Conventionally, a phenolic resin-based primer such as (all are trade names) has been used.

However, when using these primers, in order to satisfy both the curing of the urethane elastomer and the adhesive strength of the primer, it is necessary to heat the elastomer at a temperature of 100 to 120 ° C. for several hours to one day and night. Is economically disadvantageous and is not preferable in terms of workability.

If a urethane elastomer that cures at room temperature to a relatively low temperature with a small amount of heating is used, it is economical in terms of heat energy during curing, but on the other hand, a primer is required to be able to bond at a low temperature.

The above-mentioned phenol resin-based primer itself is a heat-curable type, requires baking at the time of adhesion, and has a temperature of 100 ° C.
It was not applicable at lower heating temperatures because it was difficult to obtain satisfactory adhesive strength.

Urethane-based, epoxy-based, and other silane-based primers are known as room-temperature-curable primers, but these primers can be used to bond room-temperature-curable urethane elastomers with the same high strength as adiprene to metals. When it is used, even if it is adhered at room temperature, only a weak adhesive force that can be peeled by hand is obtained. Further, in the case of a urethane-based or epoxy-based primer, a good initial adhesive strength can be obtained by heating at the time of bonding, but none satisfying water resistance and heat resistance.

[Object of the Invention]

Therefore, in order to obtain a primer composition having early development of initial adhesive strength, strong adhesion, and water resistance and heat resistance when the urethane elastomer that is cured at room temperature or by heating is adhered to a metal. As a result of diligent studies, by using a composition in which an epoxy resin is mixed with an isocyanate component used for a urethane-based primer, unexpectedly excellent adhesiveness can be obtained for the above purpose with relatively little heating at relatively low temperature. The inventors have found that and reached the present invention.

That is, the present invention, as a primer, a polyisocyanate compound containing 5 to 50% by weight of an isocyanate group or a urethane prepolymer having an isocyanate group at the end, and a blend of a polyepoxy compound having an average molecular weight of 200 to 10,000 on a metal surface. The present invention relates to a method for adhering a urethane elastomer and a metal, which comprises coating, and then injecting a urethane elastomer stock solution thereon to cure.

[Structure of Invention]

 The present invention will be described in detail below.

The primer used in the present invention is a two-pack type and is composed of a component containing an isocyanate compound or a urethane prepolymer having an isocyanate group at the terminal, and a component containing a polyepoxy compound.

Isocyanate group content as a component of the primer (weight% of isocyanate group in isocyanate compound, hereinafter referred to as NCO%) 5 to 50%, preferably 10 to 35%
As the isocyanate compound, an aromatic, aliphatic or alicyclic isocyanate monomer having at least two NCO groups in the same molecule, a mixture thereof, or a modified product thereof is used.

Specific examples include tolylene diisocyanate (TDI,
2,4-body alone or a mixture with 2,6-body), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (MDI), low polycondensate of aniline and formaldehyde, and phosgene A polynuclear polyisocyanate (crude-MDI) obtained by a reaction with, a calpositimide-modified MDI, hexamethylene diisocyanate (HMDI),
Examples include isophorone diisocyanate (IPDI) and hydrogenated MDI.

It is also possible to use a urethane prepolymer having an NCO group at the terminal and having an NCO% of 5 to 50% obtained by reacting these isocyanate compounds with a polyhydroxy compound. (The urethane prepolymer is a reaction product with an isocyanate compound and contains an unreacted isocyanate compound. In this case, NCO% is the weight% of the NCO group contained in the mixture.) As the polyhydroxy compound, Polyether polyols and polyester polyols that are commonly used in the production of polyurethane are used. For example, polyalkylene having an average molecular weight of 300 to 10,000 obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide to a polyhydric alcohol such as ene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol, and suucrose. An ether polyol or tetrahydrofuran having an average molecular weight of 600 to 10,000 obtained by ring-opening polymerization is used as a polyether follyol such as polytetramethylene ether glycol, or ethylene glycol, propylene glycol, 1,4-butanediol, hexylene glycol, diethylene glycol. Obtained by the condensation reaction of a bifunctional alcohol such as dipropylene glycol and adipic acid, succinic acid, azelaic acid, phthalic acid and the like. Average molecular weight of 300
To 6,000 are obtained by ring-opening polymerization of polyester polyol and caprolactone, and have an average molecular weight of 300 to 100,00.
Examples thereof include polycaprolactone polyester polyols having a hydroxyl group at the 0 terminal.

Usually, an isocyanate compound or urethane prepolymer having an NCO% of 5 to 50% can be used.
If 10% to 35% is used, a better adhesive material can be obtained. Further, in order to obtain a high adhesive force, an aromatic polyisocyanate such as MDI or crude MD is used.
Preferred are urethane prepolymers obtained from I, carbodiimide-modified MDI, or their isocyanates, alone or as a mixture.

Further, in the present invention, a polyepoxy compound having an average molecular weight of 200 to 10,000 is essential as a component of the primer, and specific examples thereof include an average molecular weight of 200 obtained by adding epichlorohydrin to bisphenol A.
Polyepoxy hydrin obtained by adding epichlorohydrin to a polyphenol resin obtained by condensation of ~ 10,000 terminal epoxy group-containing compound, phenol compound such as phenol, cresol, resorcin, and aldehyde such as formaldehyde, glyoxal, acrolein, etc. Examples include compounds.

A commercially available product can be used as the polyepoxy compound, and for example, Epicoat 828, 1 manufactured by Yuka Shell Epoxy Co., Ltd.
001, 1004, 1007, 1009 or Epicoat 152, 154 (Epicote is a trademark), or Ciba-Geigy Araldite EPN-1138, 113.
9, ECN-1235, 1273, 1280 (Araldite is a trademark) and the like. These are used alone or as a mixture. When more heat resistance is required, a polyfunctional polyphenol epoxy compound is preferable.

These polyepoxy compounds are 1 to 300 per 100 parts by weight of the isocyanate compound or urethane prepolymer.
It is used in a proportion of parts by weight, preferably 5 to 100 parts by weight.

As the primer solvent, a solvent that dissolves an isocyanate compound, a urethane prepolymer and a polyepoxy compound, respectively, and is inert to the isocyanate group and the epoxy group is used. Examples thereof include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, trichlene, cellosolve acetate, ethyl acetate and butyl acetate. The amount of solvent used is 0.4 to 30 times by weight, preferably 0.5 to the total amount of resin solids.
10 to 10 times by weight.

Further, a solvent having a strong swelling action, for example, a polar solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone can be used together.

In the primer composition, if necessary, a tertiary amine such as diazadicyclooctane or an organometallic compound such as dibutyltin dilaurate or lead octylate, which is generally used to accelerate the urethanization reaction, can be used as a catalyst.

Also, if necessary, extender pigments such as calcium carbonate and talc, color pigments such as titanium oxide and carbon black, lead silicate, rust preventive pigments of calcium leadate, flow regulators such as finely divided silica, and other silane coupling agents. , A plasticizer, etc. may be added.

The urethane elastomer used in the present invention is usually an isocyanate group-containing urethane prepolymer (hereinafter referred to as the main component) obtained by the reaction of a polyether polyol or polyester polyol and an isocyanate compound.
And a polyether polyol or polyester polyol and a mixed solution containing a chain extender, a catalyst and the like (hereinafter referred to as a curing agent) are mixed, cast, and cured to produce the resin. (The main agent and the curing agent are called undiluted solution of urethane elastomer.) What is the polyether polyol in the main agent and the curing agent?
Compounds obtained by adding ethylene oxide, propylene oxide, butylene oxide, etc. to ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, etc., or obtained by ring-opening polymerization of tetrohydrofuran Compounds are preferable, and those having an average molecular weight of 700 to 10,000 are suitable and used.

Polyester polyols include difunctional alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, hexylene glycol, diethylene glycol and dipropylene glycol and difunctional carboxylic acids such as adipic acid, succinic acid, azelaic acid and phthalic acid. Average molecular weight 700-6,000 obtained by condensation reaction with
The terminal hydroxy group compound and the terminal hydroxy group compound having an average molecular weight of 700 to 6,000 obtained by ring-opening polymerization of caprolactone are preferably used.

These glycols and digalbonic acid, which are raw materials for the polyester polyol, may be used alone or in combination.
Polyether polyol and polyester polyol are
A single type or a mixture of two or more types may be used.

As a polyisocyanate compound as a raw material of the main agent,
Tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), and compounds obtained by partially carbodiimidizing MDI are preferable.

The NCO% of the main agent is preferably 2 to 25%, and is preferably 3 to 15% from the viewpoints of workability and cured physical properties.

As the chain extender, short chain diols such as ethylene glycol, diethylene glycol, 1,4-butanediol and hexylene glycol, and aromatic diamines such as methylenebis (O-chloroaniline) and methylenedianiline can be used.

As the catalyst, tertiary amines such as diazabicyclooctane generally used for accelerating the urethanization reaction, or organometallic compounds such as stannas octate, dibutyltin dilaurate and lead octylate can be used.

In addition, various inorganic fillers, colorants, plasticizers and the like may be added to the urethane elastomer stock solution, if desired.

Examples of the metal to which the urethane elastomer is attached include iron, stainless steel, aluminum and brass. When these metals are adhered to a urethane elastomer, the adherend is usually degreased to obtain a strong adhesive force and durability.
It is used after sand blasting, grind blasting or various chemical treatments.

A method for adhering a metal and a urethane elastomer using the above primer composition is shown below. First, the primer composition of the present invention is uniformly dissolved in a solvent on a surface to which a metal has been subjected to a surface treatment, and an amount such that the thickness when dried is 5 to 200 μ, preferably 10 to 100 μ is applied. , Usually 3 at room temperature
The solvent is removed by air-drying for less than an hour, preferably by hot-air drying. The adhered steel sheet may be at room temperature, but may be preheated.

Next, the main component of the urethane elastomer stock solution and a curing agent are mixed and poured over it to a predetermined thickness to cure.

After that, when post-heated at 60 to 120 ° C., preferably 70 to 100 ° C. for about 1 hour and left at room temperature for about 1 week, the physical properties of the urethane elastomer are stabilized and a strong adhesive force is obtained.

As described in detail above, by using the primer composition, in the case of adhering a urethane elastomer that cures at room temperature or with heat to a metal, an adhesive having good adhesion can be obtained by heating with relatively little heat,
Moreover, the obtained adhesive has good water resistance and heat resistance.

〔Example〕

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

Production Examples-1 to 6 (Production of Primer) In a three-necked separable flask, a polyisocyanate compound and a polyhydroxy compound were reacted with each other in a solvent or without a solvent at 70 ° C. for 4 hours under a dry nitrogen atmosphere to form a urethane prepolymer. Manufactured.

A component containing a polyisocyanate compound or a urethane prepolymer was used as liquid A. Type and amount (g) of the raw material used for the liquid A, and isocyanate group content (NCO) in the solid content
%) Is shown in Table-1.

Further, a component prepared by uniformly dissolving the polyepoxy compound in a solvent was used as the liquid B. The types and amounts (g) of the raw materials used for the liquid B are also shown in Table-1.

Production Example-7 (Production of Urethane Elastomer Stock Solution) Polytetramethylene ether glycol having an average molecular weight of 1000 (hereinafter referred to as PTMG1000) 10 kg and 80 / 20-
Mix with 5 kg of TDI and react at 70 ° C for 4 hours, then NC
A urethane prepolymer having an O% of 10.3% was obtained. This stock solution is called T solution.

On the other hand, 7.5 kg of PTMG1000 and methylenebis (O
(Chloroaniline) (2.5 kg) and diazabicyclooctane (30 g) were mixed and heated to 100 ° C. to obtain a uniform liquid.
This undiluted solution is called R solution.

Production Example-8 (Production of Urethane Elastomer Undiluted Solution) PTMG1000, 10 kg and diphenylmethane diisocyanate (manufactured by APTJYON, trade name Isonate 125)
M) 10 kg were mixed and reacted in the same manner as in Production Example-7 to produce N.
A urethane prepolymer having a CO% of 12.5% was obtained. This undiluted solution is called M solution.

On the other hand, 870 g of PTMG, 130 g of 1,4-butanediol and 0.1 g of dibutyltin dilaurate were mixed and heated to 50 ° C. to obtain a uniform liquid. G of this stock solution
Called liquid.

Example 1 A 70 × 150 × 3.2 mm steel plate degreased with trichlene was subjected to surface treatment by sandblasting, and then A obtained in Production Example-1
Liquid 100 g and liquid B 180 g were uniformly mixed and applied to a uniform thickness using a bar coater No. 60, and left at room temperature for 10 minutes, and then the solvent was removed in an oven at 80 ° C. for about 10 minutes. The dry film thickness of the primer at this time was about 30 μm.

After allowing the steel sheet to cool, 300 g of the urethane elastomer stock solution, 300 g of the T solution and 200 g of the R solution obtained in Production Example-7 were respectively added.
Defoam for about 20 minutes under reduced pressure of 10 mmHg at ℃, mix for about 1 minute so as not to entrain air with a stirrer, and pour the mixed solution onto the primer applied previously so that the thickness will be about 6 mm. ,
After 1 hour of curing, it was post-heated at 80 ° C. for 1 hour.

Then, the adhesive was cured at 23 ° C. and 60% RH (relative humidity) for 1 week.

<Measurement method of initial adhesive strength> When measuring the initial adhesive strength of the adhesive, make two parallel cuts with a width of 20 mm in the longitudinal center of the test piece until reaching the steel plate surface, peel off one end and make a grip. 5 at 90 °
The peel strength was measured by pulling at a speed of 0 mm / min.

<Water Resistance Test Method> The water resistance of the adhesive was tested by the following method.

After sealing the ends of the test pieces with a sealing material, the test pieces were immersed in warm water of 50 ° C. and left at a uniform temperature for 30 days, and then the 90 ° peel strength was measured by the method described above.

The results measured by the above method are shown in Table-2.

Examples-2 to 8 A urethane elastomer was adhered to a steel sheet in the same manner as in Example 1 using the primer compositions and urethane elastomers shown in Table-2. The results are shown in Table-2.

The amount (g) of each component used is as follows.

<Primer composition> A liquid B liquid Example-2 100 g 164 g 〃 3 〃 50 g 〃 4 〃 〃 〃 5 〃 〃 〃 6 〃 60 g 〃 7 〃 〃 main 〃 8 〃 main 〃 8 〃 2 300g 200g 〃 3 〃 〃 〃 4 〃 〃 〃 5 〃 〃 〃 6 〃 〃 7 〃 8 〃 8 〃 8 〃 8 The same defoaming treatment as in ~ 6 was performed.

Table 2 shows the results of the adhesion test. In each case, the initial adhesion was 20 kg / cm or more after standing at room temperature for 7 days, and the adhesion was strong enough to cause cohesive failure of the elastomer. Further, a relatively good adhesive strength was obtained even after being left at room temperature for 1 day.

On the other hand, in terms of water-resistant adhesive strength, it is 30 in the 50 ° C hot water immersion test.
After a day, it had a good adhesive strength of 10 kg / cm to 20 kg / cm or more. Those exhibiting a water-resistant adhesive strength of 20 kg / cm or more were cohesive failure of the elastomer as in the initial adhesion.

Comparative Example-1 PP-200 (manufactured by Sanyo Kasei Co., Ltd.) was added to a steel plate treated in the same manner as in Example, with respect to 100 g of solution A (urethane prepolymer solution) of the primer composition commonly used in Production Examples-3 to 5.
Polyether polyol, molecular weight 200) 65 g of a solution of 145 g of methyl ethyl ketone dissolved in 50 g was added and uniformly mixed, and a bar coater # 60 was used to apply a uniform thickness. The solvent was removed in the oven for about 10 minutes. The dry film thickness of the primer at this time was about 30 μm.

After allowing the steel sheet to cool, a urethane elastomer composed of the liquid T and liquid R obtained in Production Example-7 was poured on the primer in the same manner as in Example, and after curing for 1 hour, at 100 ° C. for 1 hour,
After heating, an adhesive was obtained. The initial adhesive strength was 20 kg / cm or more after 7 days of standing at room temperature, but only 2 kg / cm was obtained after 1 day, and it could be peeled off by hand. When the adhesive strength of this adhesive was measured after 30 days of the 50 ° C. hot water immersion test, it was found to be 5 kg / cm.

Comparative Example-2 A steel plate treated in the same manner as in Example was coated with Epicoat 828 (produced by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 182 to 194) 1
00g and Versamide 125 (manufactured by Nippon General Mills Chemical Co., Ltd., epoxy resin curing agent, amine value 345) are mixed, and the composition diluted with 200 g of methyl ethyl ketone is applied as a primer to a uniform thickness using Bar Coater NO.80. And dried at 60 ° C. for 30 minutes. Then, the two-component urethane elastomer obtained in Production Example-7 was injected and cured in the same manner as described above, and after 1 hour, at 100 ° C. for 1 hour.
Post-heating was performed for a period of time to obtain an adhesive. The dry film thickness of the primer at this time was about 50 μm.

The initial adhesive strength of the adhesive is only 8 kg / cm after 7 days,
In the 50 ° C. hot water immersion test, the adhesive strength after 30 days had dropped to 2 kg / cm.

〔The invention's effect〕

As described above, according to the present invention, when a urethane elastomer that cures at a relatively low temperature is bonded to a metal, it is possible to obtain a primer composition that is firmly bonded and has water resistance and heat resistance.

Claims (1)

[Claims] 1. An isocyanate group of 5 is used as a primer.
˜50% by weight of a polyisocyanate compound or a blend of a urethane prepolymer having an isocyanate group at the end and a polyepoxy compound having an average molecular weight of 200 to 10,000 is applied to a metal surface, and then a urethane elastomer stock solution is injected onto the metal surface. A method for adhering a urethane elastomer and a metal, which comprises curing.