JPH0632859A - Moisture-curing type polyurethane resin composition and its production - Google Patents

Abstract

PURPOSE:To obtain the subject composition, excellent in bonding strength, heat resistance and storage stability and useful as an adhesive, etc., by adding a monoisocyanate to a specific polyurethane resin solution and then adding a polyisocyanate thereto. CONSTITUTION:The objective composition is obtained by adding (B) preferably 0.1-0.5wt.% monoisocyanate such as butyl isocyanate to (A) a polyurethane resin solution prepared by reacting a polyol with a diisocyanate, extending the chain of the resultant prepolymer having isocyanate groups at the terminals with a diol or a diamine in a solvent inert to the isocyanate groups and then converting the isocyanate group terminals into alkyl group terminals with a blocking agent selected from the group consisting of monoamines, monools or oximes and subsequently adding (C) preferably 5-20wt.% polyisocyanate such as toluene diisocyanate to the obtained mixture solution.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a moisture-curable polyurethane resin composition and a method for producing the same.

[0002]

2. Description of the Related Art Polyurethane resins are widely used as paints, adhesives, sealing materials, etc. because of their excellent properties such as adhesive strength and durability. Polyurethane resins used in these applications include one-pack type and two-pack type, thermoplastic type and moisture curing type. In recent years, since the one-pack type is superior to the two-pack type in terms of handleability and workability, the usage amount tends to increase in various fields.

[0003] However, the conventional one-pack type thermoplastic resin used in the fields of construction, civil engineering, food, etc., has excellent initial adhesive strength, but its heat resistance was not sufficient. In order to improve heat resistance, there is a method of blending a urethane modified product having an isocyanate group terminal, triisocyanate, polyisocyanate and the like with a polyurethane resin immediately before use.

However, in this case, it is complicated in terms of handleability and workability as in the two-pack type. Further, in the case of having a hydroxyl group or an amino group at the terminal, when the above-mentioned isocyanate is blended, the viscosity is increased or solidified due to the reaction between these groups and the isocyanate.

Further, the reaction of water in the solvent with the isocyanate also raises the viscosity and solidifies. Therefore, it was necessary to use the isocyanate within a short time after blending it. On the other hand, the moisture-curable adhesive has a drawback in that it has a low initial adhesive strength, although it has excellent adhesive strength after curing and excellent heat resistance. In particular, when these polyurethane resins are used as adhesives, it is desired that they can satisfy the initial adhesive strength and heat resistance at the same time and can be handled as a one-component type, but such adhesives have not been found so far. It was

[0006]

The object of the present invention is to have excellent adhesive strength, especially initial adhesive strength and heat resistance,
It is intended to provide a moisture-curable polyurethane resin composition which can be handled as a one-pack type and has excellent storage stability.

[0007]

According to the present invention, (a) a prepolymer having an isocyanate group at an end obtained by reacting a polyol with a diisocyanate is treated with a diol or a diamine in a solvent inert to the isocyanate group. After chain extension, comprises an alkyl group-terminated polyurethane resin solution in which the isocyanate group end is blocked with a blocking agent selected from the group consisting of monoamine, monool or oxime, (b) monoisocyanate, and (c) polyisocyanate. The present invention relates to a moisture-curable polyurethane resin composition. The present invention also relates to a method for producing a moisture-curable polyurethane resin composition, which comprises adding monoisocyanate and then polyisocyanate to a polyurethane resin solution. After adding the monoisocyanate, it is preferable to heat at 20 to 120 ° C. for 0.5 to 24 hours.

To prepare the polyurethane resin solution, first, diisocyanate and polyol are NCO / O.
H equivalent ratio is 1.05 to 4, preferably 1.05 to 1.95.
To prepare a prepolymer. The reaction may be carried out in the presence of a solvent inert to the isocyanate group, or may be carried out without a solvent. The reaction is 20 to
It is carried out at 140 ° C., preferably 40 to 120 ° C., for 1 to 24 hours, preferably 1 to 12 hours. After the reaction is completed, an inert solvent is added to the isocyanate group to adjust the concentration of the prepolymer.

A diol or diamine is added to the obtained prepolymer solution containing an isocyanate group to extend the chain, and then a blocking agent is added to block the isocyanate group. The amount of the diol or diamine used is 5 to 98% equivalent, preferably 40 to 90% equivalent to the terminal isocyanate group of the prepolymer. The chain extension reaction is 20 to
It is performed at 80 ° C. for 5 to 50 hours.

The blocking agent is selected from the group consisting of monoamines, monools and oximes. Blocking is confirmed by measuring the amount of isocyanate groups present at intervals of several hours. Blocking is 20-8
It is performed at 0 ° C. for 1 to 50 hours. Then, the polyurethane resin solution is obtained by again adjusting the concentration with a solvent inert to the isocyanate group.

The diisocyanate used in the preparation of the prepolymer is, for example, toluene diisocyanate, diphenylmethane diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate.

The polyol used for producing the prepolymer is, for example, addition polymerization of propylene oxide and / or ethylene oxide to polyhydric alcohol such as ethylene glycol, propylene glycol and glycerin, water, polyvalent amine such as ethylenediamine or a mixture thereof. Thus obtained polyether diol and / or polyether triol, polytetramethylene ether diol,
Polycarbonate diol, polycaprolactone diol, polyester diol such as polyethylene adipate, and polybutadiene diol.

Examples of the diol or diamine used in the chain extension reaction include diols such as diethylene glycol, butanediol, pentanediol, hexanediol and neopentyl glycol, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, diphenylmethanediamine, hydrogen. A diamine such as diphenylmethane diamine.

The blocking agent for blocking the isocyanate group is a monoamine such as dimethylamine, diethylamine and dibutylamine, a monoalcohol such as methyl alcohol, ethyl alcohol and propyl alcohol, and an oxime such as methyl ethyl ketoxime. The amount of the blocking agent used is 1 equivalent or more, preferably 1.05 to 1.5 equivalents, relative to the isocyanate group.

Examples of the solvent inert to the isocyanate group include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and heptane, esters such as ethyl acetate and butyl acetate, ketones such as acetone and methyl ethyl ketone, Examples thereof include ether esters such as ethyl cellosolve acetate and butyl cellosolve acetate. The polyurethane resin solution is 10 to 90% by weight, preferably 50 to
It contains 80% by weight of solvent. The molecular weight of the polyurethane resin is 10,000 to 100,000.

Monoisocyanates are aliphatic isocyanates such as butyl isocyanate, cyclohexyl isocyanate; aromatic isocyanates such as toluenesulfonyl isocyanate, chlorophenyl isocyanate, dichlorophenyl isocyanate, phenyl isocyanate. Monoisocyanate reacts with water in the solvent to form a solvent-soluble urea. Therefore, even if the polyisocyanate is added, the viscosity of the solvent due to the reaction between the water and the polyisocyanate does not increase and the solidification is not observed, and the composition can maintain the liquid state. The monoisocyanate is added in an amount that completely reacts with the water in the solvent. It is possible to add an excess of monoisocyanate that is more than the amount that completely reacts with the water in the solvent, but it is not preferable to add too much in terms of odor after application of the adhesive and from the viewpoint of cost.

Polyisocyanate is a compound containing two or more isocyanate groups, for example, a compound containing an isocyanate group which reacts with an active hydrogen-containing compound such as polyol or water.

Examples of the polyisocyanate include diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate, 4,4 ', 4 "-triphenylmethane. Triisocyanates such as triisocyanate, 4,4 ′, 4 ″ -tris (p-isocyanatophenyl) thiophosphate, urethane modified products of these isocyanates, isocyanurate modified products, carbodiimide modified products,
It is a polyfunctional isocyanate such as polymethylene polyphenyl polyisocyanate.

As the polyisocyanate, a urethane modified product of toluene diisocyanate, for example, Sumidule L-75 manufactured by Sumitomo Bayer Urethane Co., or an isocyanurate modified product of toluene diisocyanate, for example, Desmodur IL manufactured by Bayer Co. is particularly preferable. The monoisocyanate and polyisocyanate can be used alone or in combination.

When the amount of the polyurethane resin solution is large, the initial adhesive strength is high, but the heat resistance is low. On the other hand, when the polyurethane resin solution is small, the initial adhesive strength is low. The polyurethane resin solution is 75 to 95% by weight of the composition, preferably 80 to 9%.
It is 5% by weight. Monoisocyanate is used in the composition of 0.
It is from 05 to 1% by weight, preferably from 0.1 to 0.5% by weight. 2 to 25% by weight of the composition of polyisocyanate,
It is preferably 5 to 20% by weight.

[0021]

EXAMPLES The present invention will be specifically described with reference examples, examples and comparative examples. Unless stated otherwise, parts are parts by weight,
% Means% by weight.

Reference Example 1 Preparation of Polyurethane Resin Solution (a-1): 156 parts of diphenylmethane diisocyanate, polyester diol consisting of adipic acid and 1,6-hexanediol (molecular weight =
2000) 1000 parts and methyl ethyl ketone 500
The parts were mixed and reacted at 75 ° C. for 8 hours. After the reaction,
Add 1960 parts of methyl ethyl ketone to bring the concentration to 32%.
Adjusted to. The obtained prepolymer had a content of terminal isocyanate groups of 0.25%. 97 equivalent% of isophoronediamine was added to the terminal isocyanate groups of this prepolymer, and after chain extension reaction at 50 ° C. for 8 hours, 1 part of dibutylamine was added and reacted at 50 ° C. for 2 hours to block the isocyanate groups, Polyurethane resin solution (a
-1) was obtained.

Reference Example 2 Preparation of polyurethane resin solution (a-2): Toluene diisocyanate (2,4-isomer / 2,6-isomer = 80/2
0) 53 parts, 500 parts of a polyester diol (molecular weight = 2000) consisting of adipic acid and 1,4 butanediol and 237 parts of methyl ethyl ketone were mixed and reacted at 75 ° C. for 8 hours. As the catalyst, 0.07 part of dibutyltin dilaurate was used. After completion of the reaction, 930 parts of methyl ethyl ketone was added to adjust the concentration to 32%. The obtained prepolymer has a content of terminal isocyanate groups of 0.
It was 20%. 70 equivalent% of isophoronediamine is added to the terminal isocyanate group of this prepolymer, and the chain extension reaction is carried out at 50 ° C. for 10 hours. Block the polyurethane resin solution (a
-2) was obtained.

Example 1 1000 parts of the polyurethane resin solution (a-1) was diluted with 1000 parts of methyl ethyl ketone. Then, 4.4 parts of cyclohexyl isocyanate was added and reacted at 40 ° C. for 4 hours. Furthermore, 200 parts of Sumidule L-75 was added and mixed well to obtain a moisture-curable polyurethane resin composition.

Using this one-pack type moisture-curable polyurethane resin composition, two vinyl chloride films were adhered at a coating amount of about 200 g / m ² (wet). Immediately after that, the adhesive strength and the heat resistance were measured after 3 hours and 24 hours. The adhesive strength was measured by T-shaped peeling, and the heat resistance was measured by the method of elevated temperature creep peeling. The composition of the polyurethane resin composition is shown in Table 1. The results are shown in Table 2. The polyurethane resin composition remained liquid at room temperature for 6 months or more.

Example 2 Instead of the polyurethane resin solution (a-1), 1000 parts of the polyurethane resin solution (a-2) was replaced with cyclohexyl isocyanate, 4.4 parts of toluenesulfonyl isocyanate and Sumidule L-75. The same procedure as in Example 1 was repeated except that 200 parts of Death Module IL was used. The composition of the obtained polyurethane resin composition is shown in Table 1. The results are shown in Table 2. The polyurethane resin composition remained liquid at room temperature for 6 months or more.

Comparative Example 1 The same procedure as in Example 1 was repeated except that Sumidur L-75 was not used. The composition of the obtained polyurethane resin composition is shown in Table 1. The results are shown in Table 2.

Comparative Example 2 The same procedure as in Example 1 was repeated except that cyclohexyl isocyanate was not used. The composition of the obtained polyurethane resin composition is shown in Table 1. The results are shown in Table 2. The viscosity of the polyurethane resin composition increased about 3 times at room temperature after 2 days and completely solidified after 7 days.

Comparative Example 3 The same procedure as in Example 2 was repeated except that the desmodur IL was not used. The composition of the obtained polyurethane resin composition is shown in Table 1. The results are shown in Table 2.

Comparative Example 4 The same procedure as in Example 2 was repeated except that toluenesulfonyl isocyanate was not used. The composition of the obtained polyurethane resin composition is shown in Table 1. The results are shown in Table 2. The viscosity of the polyurethane resin solution increased to about 3 times after 2 days at room temperature and completely solidified after 6 days.

[0031]

[Table 1]

[0032]

[Table 2] Adhesive strength (Kg / inch) Heat resistance (° C) Time change Immediately after 3 hours After 24 hours Example 1 2.4 14.8 34.6> 120 6 months liquid Example 2 2.9 21.8 22.7> 120 6 months liquid Comparative Example 1 5.2 8.6 16.7 65 Liquid for 6 months Comparative Example 2 2.5 15.6 33.9> 120 Solidified in 7 days Comparative Example 3 4.2 7.8 14.2 55 6 months Liquid in Comparative Example 4 2.5 20.4 23.3> 120 Solidified in 6 days

[0033]

The composition of the present invention has excellent adhesive strength, particularly initial adhesive strength and heat resistance, and excellent storage stability. The composition of the present invention can be used as a one-component adhesive. When used as an adhesive, the adherend is various resins that may be foams, such as polyethylene, polypropylene, polyurethane, polyvinyl chloride, ABS resin, rubber, wood and the like. The composition can be applied to the adherend using a sprayer, a brush, a roll coater, or the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Nakano 3-13-26 Kuguchi, Amagasaki City, Hyogo Prefecture Sumitomo Bayer Urethane Co., Ltd. (72) Hiromi Nagura 3--1326 Kuguchi, Amagasaki City, Hyogo Prefecture Sumitomo Bayer Urethane Co., Ltd.

Claims (2)

[Claims] 1. A prepolymer having an isocyanate group at the terminal obtained by reacting (a) a polyol with a diisocyanate in a solvent inert to the isocyanate group,
After chain extension with a diol or diamine, an alkyl group-terminated polyurethane resin solution in which the isocyanate group terminal is blocked with a blocking agent selected from the group consisting of monoamine, monool or oxime, (b) monoisocyanate, and (c) polyisocyanate A moisture-curable polyurethane resin composition comprising: 2. A prepolymer having a terminal isocyanate group obtained by reacting a polyol with a diisocyanate is chain-extended with a diol or a diamine in a solvent inert to the isocyanate group, and then formed of a monoamine, monool or oxime. A polyurethane resin solution (a) is prepared with an isocyanate group terminal as an alkyl group terminal by a blocking agent selected from the group, and then monoisocyanate (b) is added, and then polyisocyanate (c) is added. The method for producing the moisture-curable polyurethane resin composition according to claim 1.