JPH1025464A - adhesive - Google Patents

Abstract

(57) [Problem] To provide an adhesive capable of firmly bonding a crosslinked polyurethane and a metal. An adhesive comprising a thermoplastic polyurethane (A) and a terminal isocyanate group-containing compound (B), wherein the thermoplastic polyurethane (A) has a terminal isocyanate group having an average number of functional groups of 2 to 2.2. Containing compound (I), a terminal hydroxyl group-containing compound (I) having an average number of functional groups of 2 to 2.2 and a number average molecular weight of 500 to 5000
I) and a short-chain terminal hydroxyl group-containing compound (III) having an average number of functional groups of 2 to 2.2 and a number average molecular weight of 50 to 500, and the terminal isocyanate group-containing compound (B) Has a number average molecular weight of 50 to 500.
An adhesive which has been modified with a modifying agent which is:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive capable of firmly bonding a crosslinked polyurethane and a metal.

[0002]

2. Description of the Related Art Crosslinked polyurethane is widely used as various cushioning materials, railway track pads and the like. When the cross-linked polyurethane is used for such an application, it may be necessary to bond the cross-linked polyurethane to a metal such as stainless steel, for example, as in a case where the cross-linked polyurethane is used as a railway track pad.

[0003] As a method of firmly bonding a crosslinked polyurethane and a metal, a method of applying a polyurethane in a molten state or a liquid state in which a reaction is not completed to a metal, and then simultaneously bonding the polyurethane at the time of crosslinking is common. However, for example, railway track pads using cross-linked polyurethane,
Designs such as vertical grooves are applied to the surface for the purpose of reducing stress and generating moderate elasticity. In the above-mentioned bonding method, in such a case, grooves are formed in the mold, so that the mold is taken out after crosslinking. Can not be applied.

As a method for bonding the crosslinked polyurethane and the metal, there is a method using a hot-melt adhesive, but equipment for heating and melting the hot-melt adhesive is required, which is disadvantageous in cost. Also, the shape of the bonding surface,
If the structure is complicated, it is not suitable. Although there is a method using an adhesive such as an adhesive tape, it is not possible to exhibit sufficient adhesive strength.

[0005]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an adhesive capable of firmly bonding a crosslinked polyurethane and a metal.

[0006]

The present invention provides an adhesive comprising a thermoplastic polyurethane (A) and a terminal isocyanate group-containing compound (B), wherein the thermoplastic polyurethane (A) has an average number of functional groups of 2 Isocyanate group-containing compound (I) having an average functionality of 2 to 2.2
2.2, a terminal hydroxyl group-containing compound (II) having a number average molecular weight of 500 to 5000, and a short chain terminal hydroxyl group having an average number of functional groups of 2 to 2.2 and a number average molecular weight of 50 to 500. It is an adhesive comprising the compound (III), wherein the terminal isocyanate group-containing compound (B) is modified with a modifier having a number average molecular weight of 50 to 500. Hereinafter, the present invention will be described in detail.

The thermoplastic polyurethane (A) used in the present invention comprises a terminal isocyanate group-containing compound (I), a terminal hydroxyl group-containing compound (II), and a short chain terminal hydroxyl group-containing compound (III). The terminal isocyanate group-containing compound (I) is not particularly limited, and includes, for example, 2,4-tolylene diisocyanate.

The number average molecular weight of the terminal hydroxyl group-containing compound (II) is from 500 to 5,000. If it is less than 500, the adhesive film lacks flexibility, and if it exceeds 5,000,
Since it is too soft to obtain a sufficient adhesive strength, it is limited to the above range. Preferably, 1000-3
000. The terminal hydroxyl group-containing compound (II) is not particularly limited, and may be, for example, crystalline under stress (orientation).
PCL and the like.

The short chain terminal hydroxyl group-containing compound (III)
Has a number average molecular weight of 50 to 500. If it is less than 50, the adhesive film lacks flexibility, and if it exceeds 500, it becomes too soft to obtain a sufficient adhesive strength, so it is limited to the above range. Preferably, 60 to 300
It is. The short chain terminal hydroxyl group-containing compound (III) is not particularly restricted but includes, for example, diethylene glycol.

In the present invention, the terminal isocyanate group-containing compound (I) and the terminal hydroxyl group-containing compound (I)
I) and the short-chain terminal hydroxyl group-containing compound (III)
It has an average functionality of 2 to 2.2. If the number of functional groups is too small, sufficient adhesive strength cannot be exhibited, and if the number of functional groups is too large, flexibility is lacking, so the content is limited to the above range. Preferably, it is 2.0 to 2.1.

In the present invention, the terminal isocyanate group-containing compound (I) is based on the total number of moles of hydroxyl groups in the terminal hydroxyl group-containing compound (II) and the number of hydroxyl groups in the short chain terminal hydroxyl group-containing compound (III). The molar ratio of the isocyanate groups in the above ()) is preferably 0.9 to 1.0. If it is less than 0.9, the resulting polyurethane does not elongate in molecular weight, so that sufficient adhesive strength is not exhibited, and
If it exceeds, the resulting polyurethane will not be thermoplastic. More preferably, it is 0.95 to 1.0.

In the present invention, the ratio of the number of moles of hydroxyl groups in the compound (II) having a terminal hydroxyl group to the number of moles of hydroxyl groups in the compound (III) having a short chain terminal hydroxyl group is 0.8 to 1.2. Is preferred. If it is less than 0.8,
If the adhesive film lacks flexibility, and exceeds 1.2, the adhesive film becomes too soft, and sufficient adhesive strength cannot be obtained. More preferably, it is 0.9 to 1.1.

The terminal isocyanate group-containing compound (B) used in the present invention has been modified with a modifying agent. Such a material is not particularly limited, and examples thereof include those obtained by modifying 2,4-tolylene diisocyanate with 1,4-butadiol. The number average molecular weight of the above modifier is 50 to 500. If it is less than 50, the adhesive film lacks flexibility, and if it exceeds 500, it becomes too soft to obtain a sufficient adhesive strength, so it is limited to the above range. Preferably, 60 to 300
It is. Such a modifier is not particularly limited, and examples thereof include 1,4-butadiol.

The number average molecular weight of the terminal isocyanate group-containing compound (B) is preferably from 200 to 1,000. If it is less than 200, the adhesive film lacks flexibility, and 1
If it exceeds 000, it will be too soft to obtain a sufficient adhesive strength. More preferably, it is 230-700.

In the present invention, based on 100 parts by weight of the thermoplastic polyurethane (A), the terminal isocyanate group-containing compound (B) has a molar number of isocyanate groups in the terminal isocyanate group-containing compound (B). 0.
It is preferably added so as to be 01 to 0.5. If it is less than 0.01, the number of reactive active points is too small, and sufficient adhesive strength cannot be exhibited. If it exceeds 0.5, the isocyanate groups are excessive with respect to the required amount, so An extra phenomenon such as a reaction with moisture occurs. More preferably, it is 0.03 to 0.3.

The adhesive of the present invention may further include, if necessary,
Plasticizers, fillers, reaction modifiers, solvents, thixotropic agents, stabilizers,
You may add compounding agents, such as a tackifier and a coloring agent. The adhesive of the present invention can be suitably used when bonding crosslinked polyurethane products such as various packings such as gaskets, oil seals and O-rings, belts, lining materials, rolls, rollers and cushioning materials to metals. In particular, it can be suitably used when manufacturing railroad track pads.

The thermoplastic polyurethane (A), which is the main component of the adhesive of the present invention, is a component compatible with the metal to be adhered and the crosslinked polyurethane. The terminal isocyanate group-containing compound (B) reacts with a hydroxyl group on the metal surface (covalent bond) and reacts with a hydroxyl group in the thermoplastic polyurethane (A) to form a metal and the thermoplastic polyurethane (A). ) And acts as an adhesive medium.

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Preparation of Crosslinked Polyurethane Sample Hyprene L-100 deaerated and kept at 80 ° C. (terminal isocyanate group weight% = 4.2, manufactured by Mitsui Toatsu Chemicals, Inc.)
And Cuamine MT (3,3'-
Dichloro-4,4'-diaminodiphenylmethane, amine equivalent = 133.5, manufactured by Ihara Chemical Co.)
The mixture was mixed at 00 / 12.7, poured into a mold kept at 100 ° C., and subjected to a crosslinking reaction for 3 hours to obtain a 2 mm thick sheet. After the obtained sheet was cured at room temperature for 7 days, it was cut into 1 inch width to obtain a strip sample. The surface of the obtained sample was washed with methylene chloride.

Preparation of Adhesive 2,4-Tolylenediisocyanate / PCL3000
(Daicel Chemical Co., Ltd.) / Diethylene glycol = 2/1
/ 1 (moles of isocyanate groups / moles of hydroxyl groups / moles of hydroxyl groups), and diluted with methyl ethyl ketone to prepare a thermoplastic polyurethane having a solid content of 35%. Using 1,4-butadiol as a modifier, terminal 2,4-tolylene diisocyanate was modified to prepare a terminal isocyanate group-containing compound having a solid content of 70%. Thermoplastic polyurethane / terminal isocyanate group-containing compound = 10
0/5 (the number of moles of isocyanate groups in the terminal isocyanate group-containing compound = 0.04 based on 100 parts by weight of the thermoplastic polyurethane) to prepare an adhesive.

180 ° Peel Test The obtained adhesive was washed with methylene chloride using S
US430 was applied with a thickness of 0.2 mm. After drying at room temperature for 10 minutes, the previously prepared strip-shaped crosslinked polyurethane sample was adhered, pressed at 1 kg / cm ² for 10 seconds, left open for 1 week at room temperature, and left at room temperature for 18 minutes at 50 mm / minute.
A 0 ° peel test was performed. Adhesive strength is 32.5kgf / c
m.

Comparative Example 1 PCL3000 (manufactured by Daicel Chemical Industries) was replaced with PEA3000.
Example 1 except that the product was manufactured by Nippon Polyurethane Co., Ltd.
A 180 ° peel test was performed in the same manner as in the above. The adhesive strength is
It was 1.5 kgf / cm.

Comparative Example 2 The procedure of Example 1 was repeated except that 1,4-butadiol was changed to PEA1000 (manufactured by Nippon Polyurethane).
An 80 ° peel test was performed. Adhesive strength is 0.5kgf / c
m.

[0024]

Since the adhesive of the present invention has the above-described structure, the surface of the adherend can be depressurized at room temperature without any special physical or chemical pretreatment by simply degreasing the surface of the adherend with a solvent or the like. Metal and the crosslinked polyurethane can be firmly bonded. Further, the present invention can also be applied to thermoplastic urethane after molding.

Claims (4)

[Claims] 1. An adhesive comprising a thermoplastic polyurethane (A) and a terminal isocyanate group-containing compound (B), wherein the thermoplastic polyurethane (A) has an average number of functional groups of 2 to 2.2. Group-containing compound (I), terminal hydroxyl group-containing compound (I) having an average number of functional groups of 2 to 2.2 and a number average molecular weight of 500 to 5000
I) and a short-chain terminal hydroxyl group-containing compound (III) having an average number of functional groups of 2 to 2.2 and a number average molecular weight of 50 to 500, and the terminal isocyanate group-containing compound (B) Has a number average molecular weight of 50 to 500.
An adhesive characterized by being modified by a modifying agent which is: 2. The amount of isocyanate groups in the terminal isocyanate group-containing compound (I) with respect to the total number of moles of hydroxyl groups in the terminal hydroxyl group-containing compound (II) and the number of moles of hydroxyl groups in the short-chain terminal hydroxyl group-containing compound (III) The adhesive according to claim 1, wherein the molar ratio is from 0.9 to 1.0. 3. A compound having a terminal hydroxyl group (I) based on the number of moles of hydroxyl groups in the compound (III) having a short terminal hydroxyl group.
3. The adhesive according to claim 1, wherein the molar ratio of the hydroxyl groups in I) is 0.8 to 1.2. 4. An isocyanate group-containing compound (B) based on 100 parts by weight of a thermoplastic polyurethane (A)
The adhesive according to claim 1, 2 or 3, wherein is added such that the number of moles of isocyanate groups in the terminal isocyanate group-containing compound (B) is 0.01 to 0.5.