JP2004196905A - Thermoplasticizable one-pack moisture-curable urethane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplasticizable one-pack moisture-curable urethane composition which can be readily peeled by a heat treatment at request after moisture-cured when applied to adhesion of, for example, a window glass of an automobile. <P>SOLUTION: The thermoplasticizable one-pack moisture-curable urethane composition comprises as the main component an isocyanate group-terminated urethane prepolymer obtained by a reaction of a polyol with an excess amount of a polyisocyanate compound, where the isocyanate group-terminated urethane prepolymer as the main component has a linear molecular structure so as to be thermoplasticized after moisture-cured. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２６】
【発明の効果】
表１の結果から、本発明（実施例１〜３）は、比較例１と比較して、１７０〜１９０℃の加熱処理によって剪断接着強度が著しく低下し、これによって容易に剥離しうることが認められる。なお、常態接着性（２．０〜３．５）については、比較例１（５．３）が大きな値となっているが、それはポリオール成分の平均官能基数が２．０７のため、硬化物の引張強度が増大したためである。
本発明の熱可塑化しうる一液型湿気硬化性ウレタン系組成物は、特に自動車窓ガラスの接着に有用であるが、広く建築、土木などの分野での接着剤やシーリング剤として適用できることは云うまでもない。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a one-pack type moisture-curable urethane-based composition which can be thermoplasticized, more specifically, an isocyanate group-terminated urethane prepolymer having an isocyanate group at a molecular terminal as a main component, and an isocyanate group-terminated urethane as the main component. Since the prepolymer has a linear molecular structure and exhibits thermoplasticity after moisture curing, for example, when applied to bonding of automotive window glass, it is easily peeled off by heat treatment after moisture curing, if desired. The present invention relates to a one-part type moisture-curable urethane-based composition that can be used.
[0002]
[Prior Art and Problems to be Solved by the Invention]
For the adhesion of automotive window glass, the main component is the above-mentioned isocyanate group-terminated urethane prepolymer, which is generally obtained by the reaction of a polyol and an excess amount of a polyisocyanate compound, and generally contains a plasticizer, a filler, a curing catalyst, etc. One-part type moisture-curable urethane compositions are used. However, due to the structure of the automobile, it is required to have adhesiveness with high strength and high durability. Therefore, if the automobile is recycled as required, it is necessary to separate the cured adhesive by decomposition. Can be done. However, this requires a very high temperature heat treatment, which causes problems such as an increase in equipment load, an increase in utility costs, and a large generation of cyan gas.
For this reason, when recycling an automobile, it is required that it can be easily peeled off at a lower heating temperature.
[0003]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to satisfy such a demand for low-temperature exfoliation, and found that, in the one-pack type moisture-curable urethane-based composition described above, the isocyanate group-terminated urethane prepolymer of the main component is linear It has been found that if it has a molecular structure in a shape and exhibits thermoplasticity after moisture curing, it can be easily peeled at a heating temperature of 200 ° C. or less, preferably 170 to 190 ° C., and has completed the present invention. [0004]
That is, the present invention relates to a one-pack type moisture-curable urethane-based composition containing, as a main component, an isocyanate group-terminated urethane prepolymer obtained by reacting a polyol with an excess amount of a polyisocyanate compound. A thermoplastic one-pack moisture-curable urethane system characterized in that a polymer (hereinafter referred to as an NCO-terminated prepolymer) has a linear molecular structure and can be thermoplasticized after moisture curing. It provides a composition.
[0005]
The NCO-terminated prepolymer used as a main component in the present invention is prepared by adding an excess amount of a polyisocyanate compound (typically, OH / NCO = 1 / 1.5 to 1 / 4.0) to various polyols by a conventional method. It is produced by reacting.
Examples of the polyol include polyoxyalkylene polyol (PPG), modified polyether polyol, and polyether polyol such as polytetramethylene ether glycol; polyester polyol such as condensation-based polyester polyol, lactone-based polyester polyol, and polycarbonate diol; Acrylic polyols, polybutadiene-based polyols, polyolefin-based polyols, polyols having a main chain of CC bonds such as saponified ethylene-vinyl acetate copolymer; and other flame-retardant polyols, phosphorus-containing polyols, halogen-containing polyols, and the like. One or more of these polyols are combined and selected so that the average of the number of functional groups (f) calculated by the following formula is less than 2, preferably 1.0 to less than 2. .
[0006]
formula:
f = (OHV / 56.1) / [[(OHV / 56.1) -USV] × (1 / fn) + USV]
Where:
OHV is a hydroxyl value (mgKOH / g)
USV is the total unsaturation (meq / g)
fn is the defined number of functional groups. The average number of functional groups of the polyol component of the NCO-terminated prepolymer is set, for example, to two or more polyol functional groups, so-called monofunctional alcohols (for example, polyoxyalkylene monool, and others). , The monools of the polyol) and the reaction product of the polyisocyanate compound, and the average number of functional groups may be set to less than 2.
[0007]
Examples of the polyisocyanate compound include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), lysine diisocyanate, and isopropyl diisocyanate. Ridene bis (4-cyclohexyl isocyanate), hydrogenated XDI, etc. are mentioned.
[0008]
By setting the average number of functional groups of the polyol component to less than 2, the obtained NCO-terminated prepolymer has a linear molecular structure, and after the moisture curing, is subjected to a predetermined heat treatment as required, so that the thermoplastic product of the cured product is cured. → It is recognized that the strength of the cured product is reduced, whereby the cured product can be easily peeled.
[0009]
In order to further improve the low temperature peeling, a thermally expandable balloon may be added. Here, the heat-expandable balloon refers to a heat-expandable substance such as a liquid gas or a low-boiling hydrocarbon, which is a heat-expandable substance such as polyvinylidene chloride, polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-methyl methacrylate copolymer, or the like. A plastic sphere encapsulated in a plastic shell is referred to as a plastic sphere.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The one-pack moisture-curable urethane-based composition that can be thermoplasticized according to the present invention comprises, as a main component, an NCO-terminated prepolymer in which the average number of functional groups of the polyol component is less than 2 (if necessary, the above-mentioned thermally expandable balloon). ), And generally comprises a system in which a plasticizer, a filler, and a curing catalyst are blended. Here, the content of the NCO-terminated prepolymer (main component) may be usually selected within the range of 20 to 60% (% by weight, the same applies hereinafter) based on the total amount of the composition.
The amount of the thermally expandable balloon may be selected so as to be 10% or less of the total amount of the composition. If it exceeds 10%, the original physical properties such as the tensile strength of the cured product tend to decrease. Usually, if a heat-expandable balloon of 0.3 to 10% is blended, the cured product becomes a foam when heated above its thermal expansion strength (around 100 ° C.), and the strength can be significantly reduced.
[0011]
Examples of the plasticizer include diisononyl phthalate, dioctyl phthalate (DOP), dibutyl phthalate, dilauryl phthalate, butylbenzyl phthalate, dioctyl adipate, diisodecyl adipate, trioctyl phosphate, tris (chloroethyl) phosphate, tris (dichloropropyl) phosphate, Examples thereof include propylene glycol adipate polyester, butylene glycol adipate polyester, alkyl epoxystearate, alkylbenzene, and epoxidized soybean oil. The compounding amount may be generally selected in the range of 5 to 50% of the total amount of the composition.
[0012]
Examples of the filler include calcium carbonate, silica, carbon black, clay, talc, titanium oxide, quicklime, kaolin, zeolite, diatomaceous earth, and the like. The compounding amount is usually in the range of 5 to 50% of the total amount of the composition. May be selected.
[0013]
Examples of the curing catalyst include organotin compounds (dibutyltin diacetylacetonate, dibutyltin dilaurate, tin octylate, dibutyltin dimaleate, etc.); 2,2′-dimorpholino diethyl ether, di (2,6-dimethylmorpholinoethyl) ) Ether; bismuth carboxylate (bismuth 2-ethylhexanoate, bismuth octylate, bismuth neodecanoate, etc.); carboxylic acid (benzoic acid, phthalic acid, 2-ethylhexanoic acid, octylic acid, stearic acid, oleic acid, linoleic acid) And the like, and the compounding amount may be usually selected in the range of 0.005 to 0.5% based on the total amount of the composition.
[0014]
Further, if necessary, an adhesion agent [the polyisocyanate compound having an inner molecular weight of less than 1,000, or the polyisocyanate compound and a silane coupling agent (mercaptopropyltrimethoxysilane, mercaptopropylmethyldimethoxysilane, γ-N-phenylamino Reaction products of propyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane, etc.); hexamethylene diisocyanate derivatives (modified buret, modified isocyanurate, modified trimethylolpropane, etc.); titanate coupling agents; solvents (Xylene, toluene, etc.); and other appropriate amounts of antioxidants, antioxidants, ultraviolet absorbers, pigments and the like may be added.
[0015]
【Example】
Next, the present invention will be described more specifically with reference to Production Examples, Examples and Comparative Examples.
Production Example 1: Production of NCO-terminated prepolymer (1) 350 g of 4,4'-diphenylmethane diisocyanate (MDI) was added to 3000 g of polyoxypropylene triol having a hydroxyl value of 25.0 (total degree of unsaturation: 0.1), and the mixture was placed in a nitrogen atmosphere. The mixture is reacted at 80 ° C. for 3 hours to obtain an NCO-terminated prepolymer A having a free NCO group content of 1.90% and a viscosity of 50,000 mPa · S (20 ° C.).
[0016]
(2) MDI (624 g) was added to 3000 g of polyoxypropylene diol having a hydroxyl value of 44.5 (total unsaturation of 0.03), and reacted at 80 ° C. for 3 hours under a nitrogen atmosphere to obtain a free NCO group content of 3%. An NCO-terminated prepolymer B of 0.000% and a viscosity of 30,000 mPa · S (20 ° C.) is obtained.
[0017]
(3) MDI (1014 g) was added to 2000 g of polytetramethylene glycol having a hydroxyl value of 108.4 (total unsaturation: 0.01), and reacted at 80 ° C. for 1 hour under a nitrogen atmosphere to obtain a free NCO group content of 5%. An NCO-terminated prepolymer C with a viscosity of 90% and a viscosity of 60000 mPa · S (20 ° C.) is obtained.
[0018]
(4) MDI (2699 g) was added to 1000 g of polyoxypropylene diol having a hydroxyl value of 567.0 (total unsaturation: 0.01), and reacted at 20 ° C. for 1 hour under a nitrogen atmosphere to obtain a free NCO group content of 12%. An NCO-terminated prepolymer D of 80% and a viscosity of 100 mPa · S (80 ° C.) is obtained.
[0019]
Example 1
350 parts (parts by weight, hereinafter the same) of NCO-terminated prepolymer B (average number of functional groups of the polyol component: 1.93) of Production Example 1 / (2), 300 parts of diisononyl phthalate, 200 parts of dry carbon black, and 200 parts of calcium carbonate Parts, 2,2'-dimorpholinodiethyl ether and 1 part of bismuth octylate are added and stirred and mixed under reduced pressure defoaming to obtain a one-pack type moisture-curable urethane composition.
[0020]
Example 2
In Example 1, except that the NCO-terminated prepolymer B (280 parts) and the NCO-terminated prepolymer C (70 parts) of Production Example 1 / (3) were used instead of the NCO-terminated prepolymer B (350 parts). (Average number of functional groups in the polyol component is 1.94), and a one-pack moisture-curable urethane-based composition is obtained in the same manner.
[0021]
Example 3
In Example 1, except that the NCO-terminated prepolymer B (310 parts) and the NCO-terminated prepolymer D (40 parts) of Production Example 1 / (4) were used instead of the NCO-terminated prepolymer B (350 parts). (Average number of functional groups in the polyol component is 1.94), and a one-pack moisture-curable urethane-based composition is obtained in the same manner.
[0022]
Comparative Example 1
In Example 1, except that the NCO-terminated prepolymer A (350 parts) of Production Example 1 / (1) was used instead of the NCO-terminated prepolymer B (350 parts) (average number of functional groups of the polyol component: 2.07) Similarly, a one-pack type moisture-curable urethane-based composition is obtained.
[0023]
Adhesion test With respect to the one-part moisture-curable urethane-based compositions of Examples 1 to 3 and Comparative Example 1, a shear test piece was prepared in the following manner, and then the shear adhesive strength under normal conditions and after heating. Is measured. The results are shown in Table 1 below.
A primer (# 435-41, manufactured by Sunstar Giken Co., Ltd.) is applied as a pre-adhesion treatment to a glass plate having a width of 25 mm and dried.
On the other hand, a primer (# 435-98, manufactured by Sunstar Giken Co., Ltd.) was applied to a coated steel sheet having a width of 25 mm coated with a baking paint for automobiles, and then dried. One-part moisture-curable urethane-based composition is applied so as to have an adhesion width of 25 mm, a thickness of 5 mm, and a depth of 10 mm, and then the above-mentioned pretreated glass plates are laminated to form a shear test piece.
[0024]
The shear test piece is allowed to stand at 20 ° C. and 65% RH for 168 hours. At this time, the normal tensile strength (MPa) is measured.
Subsequently, it is put into an oven set at 170 ° C., 180 ° C. or 190 ° C. for 5 minutes, and immediately after being taken out, the tensile strength (MPa) is measured.
[0025]
[Table 1]

[0026]
【The invention's effect】
From the results in Table 1, it can be seen that the present invention (Examples 1 to 3) significantly reduces the shear adhesive strength by the heat treatment at 170 to 190 ° C. as compared with Comparative Example 1, and thus can be easily peeled off. Is recognized. In addition, about normal adhesiveness (2.0-3.5), the comparative example 1 (5.3) has a large value, but since the average functional group number of the polyol component is 2.07, it is a cured product. This is because the tensile strength of the steel sheet increased.
The one-pack moisture-curable urethane-based composition of the present invention is particularly useful for bonding automotive window glass, but can be widely applied as an adhesive or sealing agent in the fields of construction, civil engineering, and the like. Not even.

Claims (4)

In a one-pack type moisture-curable urethane-based composition mainly composed of an isocyanate group-terminated urethane prepolymer obtained by reacting a polyol with an excess amount of a polyisocyanate compound, the main component isocyanate group-terminated urethane prepolymer has linear molecules. A one-pack moisture-curable urethane-based composition having a structure and capable of being thermoplasticized after moisture curing. The one-pack moisture-curable urethane composition according to claim 1, wherein the average of the number of functional groups (f) calculated by the following formula of the polyol is less than 2.
formula:
f = (OHV / 56.1) / [[(OHV / 56.1) -USV] × (1 / fn) + USV]
Where:
OHV is a hydroxyl value (mgKOH / g)
USV is the total unsaturation (meq / g)
fn is the number of functional groups in the definition The one-pack moisture-curable urethane composition according to claim 1 or 2, further comprising a thermally expandable balloon. The one-pack moisture-curable urethane-based composition according to any one of claims 1 to 3, which is used for bonding an automotive window glass.