JPS5951576B2 - Adhesion method between polyurethane elastomer and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of bonding polyurethane elastomers to metal.

More specifically, the present invention uses a primer to which a curing catalyst is added instead of a conventional bake-on type primer, that is, a primer that hardens by heating at 100° C. for several hours and develops adhesive strength. This invention relates to a method for forming a strong adhesive layer with metal at the same time as curing a two-component polyurethane elastomer.

The present invention uses a polyurethane elastomer that cures at room temperature to 60°C (hereinafter referred to as room temperature curing polyurethane elastomer), and such polyurethane elastomer can be used in various construction materials such as waterproofing materials, flooring materials, and sealing materials. It is widely used for
Some of them require adhesion to metal.

When adhering a cold-curing polyurethane elastomer to metal, various cold-curing primers are used. Generally, isocyanate-based primers, epoxy resin-based primers, wash primers, and silane-based primers are used. In the case of polyurethane sealants, silane-based primers modified with isocyanate and other materials are used as shown in JP-A-53-23335. It is known that adhesive strength can be maintained sufficiently even when immersed in water. However, in the case of flooring materials with high cohesive strength of polyurethane elastomers, using isocyanate-based or epoxy-based primers provides high initial adhesive strength, but the primer peels off from the metal surface when immersed in water. On the other hand, hot-cast polyurethane elastomers, such as adiprene and fluorane, which are used as materials for industrial parts such as belt rolls and solid tires, often require strong adhesion to metals. Primers based on modified products of formaldehyde condensation type thermosetting resins of polyvinyl acetal resin are widely used, such as AD-1146 from Co., Ltd. and Chemlock #218 from Burin Chemical Co., Ltd.

θ These primers are so-called baking-type primers that develop adhesive strength by heating at 100°C for several hours, but the polyurethane elastomer bonded to metal using these primers has extremely high adhesive strength compared to polyurethane solant. Despite having a large adhesive force, in some cases the adhesive strength is such that polyurethane elastomers cohesively fail. Furthermore, it is known that the adhesive strength does not decrease much even when immersed in water or the like.

We have developed a fast-curing polyurethane elastomer composition as shown in Japanese Patent Application No. 54-3377, and the urethane elastomer can be cured and demolded in 1 to 10-odd minutes at room temperature to 60°C. Its mechanical properties and abrasion resistance are fully comparable to hot-cast elastomers such as Aziprene (manufactured by DuPont).

When adhering the above-mentioned fast-curing polyurethane elastomer to metal, apply the above-mentioned baking type primer to the surface-treated metal surface and heat it at 100°C to 120°C.
If a fast-curing elastomer is applied after baking at .degree. C. for several hours (curing at room temperature to 60.degree. C.), adhesive strength close to that of hot-cast polyurethane elastomer can be obtained.

However, it is often necessary to bond the fast-curing polyurethane elastomer to metal at the same time as it is cured, and for this purpose a room-temperature curing primer is required.

Various room-temperature curing type primers used for building materials and the like were investigated, but it was not possible to obtain the same adhesive strength as when baking at 100°C to 120°C using the above-mentioned baking type primer. Therefore, the present inventors have determined that, in some cases, the elastomer can conducted extensive research in order to obtain a room temperature curing type primer that has high adhesive strength to the extent that it will cause failure.

Surprisingly, by using a conventional bake-on type primer with a strong acid added as a primer, the desired adhesive strength can be obtained by heating at room temperature to 60°C for more than 10 minutes, and even after immersion in water. The inventors have also discovered that the adhesive strength does not decrease significantly, and have arrived at the present invention.

That is, the present invention provides a method for adhering a two-component polyurethane elastomer to metal at the same time as curing, using as a primer an organic solvent solution of a modified polyvinyl acetal resin with a formaldehyde condensation type thermosetting resin to which a strong acid is added. This is a method of bonding liquid polyurethane elastomer and metal.

The polyvinyl acetal resin used in the present invention is produced by saponifying polyvinyl acetate, and converts polyvinyl alcohol into formaldehyde, acetaldehyde,
It is acetalized with butyraldehyde or the like, and various types having different degrees of acetalization and average degrees of polymerization can be used.

Examples of the formaldehyde condensation type thermosetting resin used in the present invention include phenol resin, melamine resin, urea resin,
Known materials such as guanamine resin can be used.

The polyvinyl acetal resin and the formaldehyde condensation type thermosetting resin are heated and reacted in a solvent to obtain a modified product of the former.

Examples of the organic solvent for dissolving the formaldehyde condensation type thermosetting resin modified polyvinyl acetal resin of the present invention include acetone, ketones such as methyl ethyl ketone and methyl isobutyl ketone, methanol, ethanol,
Alcohols such as “isopropanol”, ethyl acetate,
Esters such as n-butyl acetate, and other solvents such as toluene, xylene, trichlorethylene, methyl cellosolve, etc. alone or in combination are used.

The concentration of the modified product is 3 to 30% by weight (hereinafter % indicates weight%).

) is used. Strong acids added as catalysts to the present invention include phosphoric acid and P-toluenesulfonic acid.

The strong acid is added in an amount of 0.1 to 20%, preferably 1.0 to 15%, of the modified polyvinyl acetal resin with a formaldehyde condensation type thermosetting resin.

Metals in the present invention include iron, aluminum, brass, and the like. The room-temperature-curing two-component polyurethane elastomer of the present invention is not limited to the above-mentioned fast-curing polyurethane elastomer, and includes, for example, calcium carbonate, talc,
Polyurethane elastomers and rolls for building materials such as flooring materials, waterproofing materials, and gland materials containing various fillers such as sauce materials,
Cast polyurethane elastomers used for various industrial applications such as solid tires, polyurethane elastomers for potting, etc. are also used. Two-component polyurethane elastomers are usually prepared from a polyisocyanate and/or polyurethane prepolymer and a curing agent that includes a crosslinking component. As the polyisocyanate and/or polyurethane prepolymer, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate (65/35 , 80/20), diphenylmethane diisocyanate, so-called liquid diphenylmethane diisocyanate liquefied by various conventionally known methods such as Japanese Patent Publication No. 38-4576, crude products of tolylene diisocyanate, polymethylene polyphenyl polyisocyanate (diphenyl (crude product of methane diisocyanate), conventionally known aromatic polyisocyanates such as cyclohexylmethane diisocyanate, and mixtures of two or more of conventionally known alicyclic polyisocyanates such as cyclohexylmethane diisocyanate and isoborone diisocyanate; Various monomer polyols such as methylolpropane, polytetramethylene ether glycol, various polyether polyols obtained by adding propylene oxide or propylene oxide and ethylene oxide to various monomer polyols, polycaprolactone polyols, and various polyesters such as polyethylene adipate. Polyurethane prepolymers with polyols, 1,2-polybutadiene polyols, castor oil polyols, so-called polymers made by grating vinyl monomers, etc. These prepolymers may be added with colloidal silica or asbestos to impart thixotropic properties.

As curing agents, monomer polyols such as ethylene glycol, diethylene glycol, 1,4-butanediol, trimethylolpropane, various polyether polyols, various polyester polyols, various polymers, polyols, castor oil polyols, 3,3'-dichloro-
Aromatic polyamines such as 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenylmethane, or liquefied aromatic polyamines dissolved in plasticizers, various polyether polyols, etc., or A mixture of two or more types is used.

Further, a plasticizer, a filler such as calcium carbonate, a coloring agent, a thixotropic agent, etc. are added to the curing agent as necessary.

The primer of the present invention can be applied by conventional methods such as brushing, spraying, and pouring.

In addition, when applying the primer, in order to ensure sufficient adhesive strength, ordinary metal surface treatment methods such as
It is desirable to perform degreasing, a coat of salinoid paper, various types of blasting, or various types of chemical treatments. Next, the present invention will be explained by giving production examples, examples, and comparative examples.

Hereinafter, % and parts indicate weight % and parts by weight, respectively.

Production of primer stock solution (Hereinafter, primer stock solution refers to the solution before addition of a strong acid.) Production example l In a Mirofask equipped with a stirrer and a reflux condenser, Denka Butyral #4000-1 (manufactured by Denki Kagaku Kogyo Co., Ltd., polyvinyl butyral) was added. Resin, average degree of polymerization of about 920, vinyl butyral 75% by weight or more 1-) 140 g, Plyophene 5010 (manufactured by Dainippon Ink Chemical Industries, Ltd., phenol resin, Resoltano(P)) 120 g, and toluene + isopropanol (l: 2 weight) 790 g of the mixed solvent (ratio) was added, and the mixture was heated and stirred at 60° C. for about 1 hour to obtain a homogeneous solution.

The viscosity was 1350 cps/25°C. Production example 2 Yuvan IIHV (
Production example 1 except for using Mitsui Toatsu Kagaku Co., Ltd., urea resin)
A homogeneous solution was obtained in the same manner as above.

The viscosity was 1200 cps/25°C. Primer application method (Hereinafter, "primer" refers to a primer solution diluted with only an organic solvent, and "j" refers to a product to which a strong acid is further added.

) A primer was applied with a brush to an iron plate whose surface had been adjusted to a roughness of 50μ by grid blasting, and after air-drying at room temperature for 30 minutes, a second coat was applied and the primer was air-dried at room temperature for 30 minutes. The dry coating amount of the primer was 30-40 g/M3゜.
Adhesion test method (1) Initial adhesive strength After leaving the adhesive test piece at 25°C and 55% RH (relative humidity) for 7 days, cut the elastomer into 25 mm width and perform a 180 degree peel test at a θ tensile rate of 50 mm/min. I asked.

(2) Water resistant adhesive strength After leaving the adhesive test piece at 25°C and 55% RH for 7 days, cut the elastomer into 25 mm width, immerse it in water at 25°C or 40°C for 7 days, and pull at a tensile rate of 50 mm/min for 18 days.
A 0 degree peel test was conducted.

Example 1 To 100 g of the primer stock solution obtained in Production Example 1, 1 g of 88
% phosphoric acid to methyl ethyl ketone (hereinafter referred to as MEK) 10
A solution diluted to 0 g was added and stirred uniformly to obtain a primer.

The iron plate coated with this primer as described above was preheated at 60°C for 15 minutes, and Hypren Q-583 (polyoxytetramethylene glycol/diphenylmethane diisocyanate prepolymer manufactured by Mitsui Nisso Urethane Co., Ltd., NCO = 15 %) and 0 parts of dibutyltin dilaurate per 100 parts of Hyprene MC-532 (polyoxytetramethylene glycol curing agent manufactured by Mitsui Nisso Urethane Co., Ltd.).
．． 03 parts of the hardening agent and the pot life was adjusted to about 1 minute were mixed in a two-component polyurethane casting machine (Toho Kikai AF-
206 type), blending ratio 100:66 (weight ratio), discharge amount 5
The mixture was stirred and mixed at 0 g/Sec, and discharged to form an elastomer with a thickness of 5 mm. The results of this adhesion test are shown in Table 1.

Example 2 A solution prepared by diluting 0.2 g of P-toluenesulfonic acid in MEKlOOg was added to 100 g of the primer stock solution obtained in Production Example 1, and the mixture was stirred uniformly to obtain a primer.

Using this primer, an adhesion test was conducted in the same manner as in Example 1. The results of this adhesion test are shown in Table 1.

Example 3 An adhesion test was carried out in the same manner as in Example 1 except that the primer stock solution obtained in Production Example 2 was used.

The results of this adhesion test are shown in Table 1. Comparative Examples 1 and 2 100 g of the primer stock solution obtained in Production Example 1 or Production Example 2 was diluted by adding only MEKlOOg, and uniformly stirred to obtain a primer.

An adhesion test was conducted using these primers in the same manner as in Example 1.

These results are shown in Table 1. Comparative Example 3 MEKlOO was added to 100 g of the primer stock solution obtained in Production Example 1.
The mixture was diluted by adding only g and stirred uniformly to obtain a primer.

After applying this primer to the iron plate as described above,
It was baked by heating at ℃ for 6 hours. Next, after cooling the iron plate to 60° C., an elastomer layer was formed in the same manner as in Example 1. The results of this adhesion test are shown in Table 1.
Comparative Example 4 MEKlOO was added to 100 g of the primer stock solution obtained in Production Example 2.
The mixture was diluted by adding only g and stirred uniformly to obtain a primer.

After applying this primer to the iron plate as described above,
It was baked by heating at 0°C for 6 hours and then at 150°C for 1 hour. Next, the iron plate was cooled to 60° C., and then an elastomer layer was formed in the same manner as in Example 1. The results of this adhesion test are shown in Table 1. Example 4, Comparative Example 5, Comparative Example 6 Instead of the primer stock solution obtained in Production Example 1 or Production Example 2, Chemlock I2l8 (manufactured by Hyusung Chemical Co., Ltd., modified polyvinyl butyral primer solid content 20%, primer stock solution of the present invention) was used. An adhesion test was conducted in the same manner as in Example 1, Comparative Example 1, and Comparative Example 3.

The results of the four adhesion tests are shown in Table 1.

Example 5, Comparative Example 7, Comparative Example 8 Instead of the primer stock solution obtained in Production Example 1 or Production Example 2, Konap AD-1146 (modified polyvinyl butyral primer manufactured by Konup Co., Ltd., solid content 25%) was added to the primer stock solution of the present invention. An adhesion test was conducted in the same manner as in Example 1, Comparative Example 1, and Comparative Example 3.

The results of these adhesion tests are shown in Table 1.

Claims (1)

[Claims] 1 A method for bonding a two-component polyurethane elastomer to metal at the same time as curing, characterized in that a strong acid is added to an organic solvent solution of a modified polyvinyl acetal resin with a formaldehyde condensation type thermosetting resin as a primer. A method of bonding two-component polyurethane elastomer and metal.