JP2001003030A - Moisture-curable polyurethane hot-melt adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture-curable polyurethane hot-melt adhesive composition which shows an excellent adhesion strength and heat creep resistance at 2 hours after adhesion and also exerts an excellent heat stability and shelf stability. SOLUTION: A moisture-curable polyurethane hot-melt adhesive composition is prepared by allowing a mixture wherein 100 pts.wt. mixed polyol containing a polyester polyol having a number average molecular weight of from 1,000 to 8,000 and a polyamine polyol having a functionality of 3 or larger, is blended with from 0.1 to 5 pts.wt. tertiary amine and from 20 to 2,000 ppm phosphoric ester, to react with excessive organic isocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a moisture-curable polyurethane hot melt adhesive composition.

[0002]

2. Description of the Related Art Moisture-curable polyurethane hot-melt adhesives exhibit a certain degree of adhesive strength by being cooled and solidified within a short period of time after bonding, and are applied to adherends such as plastics, wood materials and metals. Because of its excellent adhesiveness, it is widely used in various fields such as packaging materials, automobiles, woodwork, building materials, bookbinding and the like.

[0003] However, the moisture-curable polyurethane hot melt adhesives used in these fields have insufficient initial adhesive strength such as initial adhesive strength and initial heat creep resistance. Requested.

[0004] For example, when a moisture-curable polyurethane hot melt adhesive is applied to an automobile interior skin material, the skin material is incorporated into an automobile in a short time after bonding,
The car is then moved to an outdoor motor pool approximately six hours later and left in the sun. For this reason, the interior of the vehicle is heated to a considerably high temperature, and an adhesive having an initial heat-resistant adhesive strength that can withstand the temperature is required.

[0005] The conventional moisture-curable polyurethane photomelt adhesive requires a long time of one week or more to completely cure the moisture. In this regard, the conventional moisture-curable polyurethane photomelt adhesive can be applied at room temperature. There is no difference from the system adhesive.

Therefore, in order to improve the initial adhesiveness of the moisture-curable polyurethane photomelt adhesive, a method of using a metal catalyst or an amine catalyst in combination to accelerate the moisture-curing reaction has been studied.

[0007] However, by using a metal catalyst or an amine catalyst together, for example, the desired adhesive strength and heat creep resistance can be obtained within 2 hours after bonding. The phenomenon of thickening or gelling and extremely lowering of thermal stability occurs, so that the situation is far from practical use.

As another method, an amine polyol obtained by adding an alkylene oxide to an aliphatic amine having 2 to 25 carbon atoms is used in an amount of 2 to 10 in the total polyol component.
A moisture-curable polyurethane adhesive obtained by blending 0% by weight with an excess of an organic isocyanate compound is disclosed in JP-A-9-67422, and the moisture-curing reaction of the urethane prepolymer is performed without impairing the storage stability. Is promoted, and an adhesive having a good initial adhesive strength is obtained.

However, the adhesive obtained by this method is a room temperature application type moisture-curable polyurethane adhesive, and the number of functional groups of the amine polyol is limited to two. Therefore, although storage stability is good, there is no initial adhesive force, and it takes 24 hours to obtain more sufficient heat resistance.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to develop excellent initial adhesion within 2 hours after adhesion by accelerating a moisture curing reaction, and to further improve heat stability and storage stability. To provide a moisture-curable polyurethane hot-melt adhesive having good moisture resistance.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a mixture of a polyester polyol having a number average molecular weight of 1,000 to 8,000, 0.1 to 5 parts by mass of a tertiary amine and 20 to 5000 ppm of a phosphoric ester is blended. On the other hand, the present inventors have found that a moisture-curable polyurethane hot melt adhesive composition obtained by reacting an excess amount of an organic isocyanate compound is an adhesive that solves the above-mentioned problems, and has completed the present invention.

A first feature of the present invention is that the polyamine polyol serves as a constituent material of the polyurethane prepolymer to be formed, and in addition to imparting a branched structure to the polyurethane prepolymer, the polyamine polyol and the tertiary amine can be used as a polyurethane prepolymer. Since it also acts as a catalyst for accelerating the moisture curing reaction of the prepolymer, excellent adhesive strength and heat creep resistance are exhibited within 2 hours after bonding. Further, the second feature of the present invention is that, by using a phosphoric acid ester, an allohanate reaction between a urethane bond and an isocyanate group in a polyurethane prepolymer molecule and a dimerization of an isocyanate group occurring between isocyanate groups occur during heating and melting. Alternatively, since the trimerization reaction is suppressed, the viscosity of the adhesive at the time of thermal melting is prevented, and good heat stability and storage stability are maintained.

The polyester polyol used in the present invention includes ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
Neopentyl glycol, 1,3 butanediol, 1,
One or two polyhydric alcohol compounds such as 4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, pentaerythritol, glycerin, castor oil and derivatives thereof Above and maleic anhydride, fumaric acid, itaconic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanoic acid, succinic acid, anhydride One kind of polyvalent carboxylic acid such as trimellitic acid or 2
A polyester polyol obtained by performing a condensation reaction from more than one kind is used.

The number average molecular weight of the polyester polyol described above ranges from 1,000 to 8,000. When the number average molecular weight is 1000 or less,
It is not preferable because the adhesive strength, moisture resistance, heat resistance, etc. after moisture curing are reduced. On the other hand, when the number average molecular weight is 8000 or more, the viscosity of the adhesive is increased and the coating property is poor, so that it is not preferable.

The amine polyol used in the present invention includes ethylamine, butylamine, octylamine,
Laurylamine, ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, propylenediamine, methylaminomethylamine, methylaminoethylamine, ethylaminoethylamine, 1,2-diaminopropane, 1,3-diaminopropane, methylaminopropyl Aliphatic such as amine, bis (3-aminopropyl) ether, 1,3-bis (3-aminopropyl) ethane, 1,4-diaminobutane, laurylaminopropylamine, iminobispropylamine, methyliminobispropylamine One or two types of polyamine polyols obtained by using an aromatic polyamine such as polyamine and meta-xylene diamine alone or as a mixture and adding an alkylene oxide thereto.
More than one kind is used, and a polyamine polyol having three or more functions is used on average. In addition, examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and the like.

The amount of the amine polyol to be used is suitably 0.5 to 20% by mass in the mixed polyol containing the polyester polyol and the amine polyol. When the amount of the polyamine polyol is 0.5% by mass or less, the effect as a moisture curing reaction catalyst is small and the effect as a polyurethane prepolymer branch structure imparting component is not exhibited. Extremely low heat creep resistance, use 2
If the content is 0% by mass or more, storage stability and thermal stability are unfavorably deteriorated.

The organic isocyanate compound used in the present invention includes tolylene diisocyanate, hydrogenated tolylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, meta-xylylene diisocyanate, tetramethyl xylylene diisocyanate,
One or more of diphenylmetane diisocyanate, hydrogenated diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like and derivatives thereof are used.

The tertiary amine used in the present invention includes:
Tripropylamine, triisopropylamine, tributylamine, triisobutylamine, tritertiarybutylamine, triamylamine, trihexylamine, trioctylamine, tri2-ethylhexylamine, methyldi-2-ethylhexylamine, dibutyl2
Monoamines such as ethylhexylamine, trihexadecylamine and tribenzylamine and polyamines such as tetramethyl1,2-diaminoethane, tetramethyl1,3-diaminopropane, tetramethylhexamethylenediamine and pentamethyldiethylenetriamine are used. .

The amount of the tertiary amine to be used must be 0.1 to 5 parts by mass with respect to 100 parts by mass of the mixed polyol containing the polyester polyol and the amine polyol. When the amount is 0.1 parts by mass or less, the effect of the polyurethane prepolymer as a moisture curing reaction catalyst is small, and when the amount is 5 parts by mass or more, thermal stability is unfavorably deteriorated.

The phosphate ester used in the present invention includes trioctyl phosphate, tridecyl phosphate, tridodecyl phosphate, trioctadecyl phosphate, triphenyl phosphate, didecylphenyl phosphate, decyldiphenyl phosphate, phosphate Trinonylphenyl and the like are used.

The amount of the phosphoric acid ester to be used is suitably from 20 to 5000 ppm based on the mixed polyol described above. If the amount is less than 20 ppm, good thermal stability is not maintained, and When the content is 5000 ppm or more, the moisture curing reaction of the urethane prepolymer is affected, and the initial adhesiveness is undesirably reduced.

In the present invention, a polyether polyol having the function of a moisture absorbent may be blended. The polyether polyol has an ethylene oxide content of 50 to 1
Those having a molar ratio of 00 mol% and a number average molecular weight of 500 to 5000 are used. When the ethylene oxide content is 50
% Or less is not preferred because the effect as a hygroscopic agent is reduced, while the number average molecular weight is 500
In the following cases, the initial adhesive strength and the initial heat creep resistance decrease, and in the case of 5,000 or more, the viscosity of the adhesive increases and the coatability decreases, which is not preferable.

The amount of the polyether polyol to be used is preferably 5 to 20 parts by mass based on 100 parts by mass of the polyester polyol described above. When the use amount of this polyether polyol is 5 parts by mass or less, the effect as a hygroscopic agent is small, and when the use amount is 20 parts by mass or more, the water resistance after moisture curing is undesirably reduced.

Further, the adhesive of the present invention may contain, if necessary, polyurethane, polyester, acrylic copolymer,
Thermoplastic resins such as polyether, ethylene-vinyl acetate copolymer, various rubbers, and petroleum resins, rosin ester resins, hydrogenated rosin ester resins, phenol resins, terpene resins, cumarone resins, xylene resins, ketone resins,
Tackifiers such as styrene resins, fillers such as calcium carbonate, talc, clay, mica, and silica, as well as solvents,
A plasticizer, an ultraviolet absorber, an antioxidant, a coloring agent, an antibacterial agent and the like are blended.

In the present invention, a polyurethane prepolymer, which is the main composition of the adhesive of the present invention, is obtained by reacting the above-mentioned organic isocyanate compound with a mixture of a polyol, a tertiary amine and a phosphate ester. .

The ratio NC between the number of isocyanate groups (hereinafter referred to as NCO) of the compounded organic isocyanate compound and the number of hydroxyl groups (hereinafter referred to as OH) of the compounded polyol
About the number of O / number of OH, NCO number / OH number = 1.3 to
It is appropriate to set the NCO content in the polyurethane prepolymer to 1.0 to 5.0% by mass by setting the content to 5.0. When the number of NCO / OH is not more than 1.3, the viscosity of the adhesive is extremely increased and the coating property is deteriorated, which is not preferable. It is not preferable because adverse effects such as an increase in foaming of the adhesive layer upon curing and a decrease in initial adhesive strength and initial heat creep resistance are caused.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to examples. The test method was performed by the method described below.

Softening point: Measured by the ring and ball method.

NCO content: Excess amine is added and NCO
After reacting with CO, the remaining amine was back titrated with hydrochloric acid and measured.

Initial adhesive strength: temperature 23 ° C., humidity 65% RH
In a constant temperature / humidity room, an adhesive heated and melted at a temperature of 120 ° C. was applied to a decorative PVC sheet at an application amount of 45 g / m ² , and immediately afterward, using a roller using a medium. Density. The sample was pressed on a fiber board (MDF) at a pressure of about 2 kg / cm ² to prepare a test piece. Next, this was left in a constant temperature and humidity room at a temperature of 23 ° C. and a humidity of 65% RH for a predetermined time, and then, using a tensile tester, a peel angle of 180 ° and a peel speed of 200 °.
The peel strength was measured at a temperature of 23 ° C. in mm / min.

Heat creep resistance: A specimen having a width of 25 mm produced under the same conditions as the initial adhesive strength was subjected to a temperature of 23 ° C. and a humidity of 65%.
After leaving it in a constant temperature and humidity chamber of RH for a predetermined time, a load of 500 g was applied at a peeling angle of 90 ° and a 1 ° C was placed in a thermostat at a temperature of 60 ° C.
After leaving for a time, the peel length was measured.

Thermal stability: After sealing the adhesive in a container filled with nitrogen gas, it was allowed to stand in a thermostat at a temperature of 120 ° C. for 8 hours, and the appearance and the change in viscosity (expressed by the viscosity ratio after test / initial) were measured. Judged.

Storage stability: After sealing the adhesive in a container filled with nitrogen gas, it was left in a constant temperature room at a temperature of 23 ° C. for 6 months.
The appearance and the change in viscosity (expressed by the viscosity ratio after / initial test) were measured and judged.

[0034]

Example 1 In a four-necked flask equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet tube, a polyester polyol (number average molecular weight 3000, OH Value 50mgK
OH / g) 98 parts by mass of propylene oxide were added to ethylenediamine and 2 parts by mass of a tetrafunctional polyamine polyol (OH value 220 mgKOH / g), 0.5 parts by mass of trioctylamine and 500 ppm of triphenyl phosphate were charged. After depressurizing and removing water, diphenylmethane diisocyanate was added therein with NCO number /
The OH number was set to 2.0, and a urethanization reaction was performed at 120 ° C. for 3 hours in a nitrogen atmosphere to obtain a moisture-curable polyurethane hot melt adhesive having an NCO content of 3.3% by mass.

[0035]

Example 2 A moisture-curable polyurethane hot melt adhesive was obtained under the same conditions as in Example 1 except that the amount of trioctylamine was increased to 1 part by mass.

[0036]

Example 3 The polyester polyol of Example 1 was added to 88
A moisture-curable polyurethane hot melt adhesive was obtained under the same conditions as in Example 1 except that the amount was reduced to parts by mass and 10 parts by mass of polyethylene glycol having a number average molecular weight of 1,000 was added.

[0037]

Example 4 The polyester polyol of Example 1 was added to 88
Parts by weight, added 10 parts by weight of polyethylene glycol having a number average molecular weight of 1000, and increased the blending amount of trioctylamine to 1 part by weight under the same conditions as in Example 1 to obtain a moisture-curable polyurethane hot melt adhesive. I got

[0038]

Comparative Example 1 A moisture-curable polyurethane hot melt adhesive was obtained from Example 1 under the same conditions as in Example 1 except that polyamine polyol, trioctylamine and triphenyl phosphate were omitted.

[0039]

Comparative Example 2 A moisture-curable polyurethane hot melt adhesive was obtained from Example 1 under the same conditions as in Example 1 except that trioctylamine and triphenyl phosphate were omitted.

[0040]

Comparative Example 3 A moisture-curable polyurethane hot melt was prepared under the same conditions as in Example 1 except that the amount of trioctylamine in Example 1 was increased to 1 part by mass, and polyamine polyol and triphenyl phosphate were omitted. An adhesive was obtained.

[0041]

Comparative Example 4 A moisture-curable polyurethane hot melt adhesive was obtained under the same conditions as in Example 1 except that the amount of trioctylamine was increased to 1 part by mass and triphenyl phosphate was omitted. .

[0042]

Comparative Example 5 The polyester polyol of Example 1 was added to 88
Parts by weight, added 10 parts by weight of polyethylene glycol having a number average molecular weight of 1000, increased the blending amount of trioctylamine to 1 part by weight, and removed the triphenyl phosphate under the same conditions as in Example 1. A moisture-curable polyurethane hot melt adhesive was obtained.

Formulation (parts by mass) of moisture-curable polyurethane hot melt adhesives of Examples 1-4 and Comparative Examples 1-5
The results of the performance tests are shown in Tables 1 and 2.

[0044]

[Table 1]

[0045]

[Table 2]

As described above, as shown in the test results in Tables 1 and 2,
The adhesives obtained from Examples 1 to 4 have softening points of 39 to 42.
° C, 120 ° C viscosity 9.6-10.5Pa. s, and the adhesive strength 2 hours after bonding was 4.3 to 4.5 kgf /
With a thickness of 25 mm, an adhesive force accompanied by breakage of the PVC sheet can be obtained, and in the heat creep resistance after 2 hours of bonding, all exhibit excellent heat creep resistance showing almost no peeling. The thermal stability after standing for 8 hours and the storage stability after standing at 23 ° C. for 6 months were both good.

[Effects of the Invention] In the moisture-curable polyurethane hot melt adhesive of the present invention, a polyamine polyol having three or more functional groups and a tertiary amine act as a moisture curing catalyst, and the polyamine polyol serves as a branch of the polyurethane prepolymer molecule. Since it also acts as an imparting component, excellent adhesive strength and heat creep resistance are developed within 2 hours after bonding. In addition, the adhesive of the present invention is excellent in storage stability and heat stability by incorporating a phosphate ester.

Continued on the front page F term (reference) 4J034 BA07 BA08 CA03 CA05 CB04 CB05 CB07 CC05 CC08 CC12 CC62 CC65 CD01 CE01 DA01 DB03 DB07 DF16 DF17 DF19 DF20 DF21 DF22 DF29 DG03 DG04 DG05 DG16 DG22 DH02 HC06 HC07 HC01 HC46 HC52 HC61 HC63 HC64 HC67 HC71 HC73 KA01 KB02 KD12 KD15 KE02 LA08 LA33 QA05 QB11 RA08 4J040 EF061 EF062 EF111 EF112 EF131 EF132 HC01 HD24 JB01 JB04 KA05 KA06 KA08 LA01

Claims (3)

[Claims] 1. A mixed polyol containing a polyester polyol having a number average molecular weight of 1,000 to 8,000 and a polyamine polyol having three or more functional groups is mixed with 100 parts by weight of a tertiary amine and 0.1 to 5 parts by weight of a tertiary amine and a phosphate ester of 20 to 5,000.
A moisture-curable polyurethane hot melt adhesive composition obtained by reacting an excess of an organic isocyanate compound with a mixture containing ppm. 2. The mixed polyol according to claim 1, wherein
Further, a moisture-curable polyurethane hot melt adhesive composition characterized by containing a polyether polyol. 3. The moisture-curable polyamine polyol according to claim 1, wherein the polyamine polyol is a trifunctional or higher functional polyamine polyol obtained by adding an alkylene oxide to an aliphatic or aromatic polyamine. Polyurethane hot melt adhesive composition.