JPH11263962A - One-pack type moisture-curable urethane liquid type adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the coating workability that is a defect in conventional one-pack non-solvent type moisture-curable urethane adhesion, impart excellent adhesion and permit the excellent behavior of prompt curing. SOLUTION: 0.1-30 mass parts of N-methyl-2-pyrrolidone is formulated to 100 mass parts of urethane polymer bearing isocyanate chain terminals to prepare a low-viscosity and high-adhesion solution. In addition, as a urethane prepolymer bearing isocyanate chain terminals, it is allowed to react with a polyoxypropylene polyol and polyester polyols prepared by reaction of polyhydric alcohol with polycarboxylic acid to prepare urethane prepolymer bearing isocyanate groups as chain terminals to improve the balance between the low viscosity and the adhesion performance. Further, at least one amine selected from bis(morpholinoethyl) ether, bis(2,6-dimethyl-morpholinoethyl) ether and bis(3,5-dimethylmorpholino-ethyl) ether is formulated to obtain a one-pack type moisture-curable urethane liquid type adhesion composition having improve prompt curing behavior.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-liquid, solvent-free, moisture-curable urethane liquid adhesive.

[0002]

2. Description of the Related Art A one-component moisture-curable urethane-based adhesive mainly comprises a urethane prepolymer having an isocyanate group at a terminal (hereinafter, referred to as a "prepolymer"), and the isocyanate group is exposed to moisture in the air or a coating. The adhesive layer is formed by reacting with moisture in the adherend to cure and crosslink, thereby bonding various adherends.

[0003] Conventionally, one-part moisture-curable urethane-based adhesives are prepared by reacting a polyol with an excess of polyisocyanate in the presence or absence of an organic solvent to form a urethane prepolymer having an isocyanate group at the terminal. A polymer was synthesized, and if necessary, a filler, an organic solvent, a thixotropic agent, a curing catalyst, and the like were blended to form an adhesive.

[0004] Among the one-component moisture-curable urethane-based adhesives, in the case of a solvent type, a large amount of a volatile organic solvent is used to dilute the solvent, so that the molecular weight of the urethane prepolymer may be extremely large. Therefore, the initial adhesiveness that is developed immediately after the evaporation of the organic solvent can provide an excellent initial tack state (hereinafter, referred to as “initial tack”) due to the characteristics of the polymer. Further, as a characteristic of the solvent type, since the organic solvent assists both the wetting effect and the diluting effect of the wettability required for adhesion, which is a disadvantage of the high-molecular polymer, the adhesiveness is also good.

The organic solvent used in the one-component solvent-type moisture-curable urethane-based adhesive has a boiling point of 100 ° C. or less typified by ethyl acetate, methyl ethyl ketone, and methylene chloride in order to obtain the initial strength of the initial tack. Or a so-called medium-boiling solvent having a boiling point of 100 ° C to 150 ° C, such as toluene, xylene or methyl isobutyl ketone, is widely used. A high-boiling point solvent, a plasticizer, and the like are used only in an auxiliary manner as needed, since drying is delayed.

[0006] These solvents have a serious problem of odor and the health of workers due to evaporation of the solvent during the coating operation, and they are flammable hazardous substances, so it is important to pay attention to fire prevention. In addition, they are subject to laws and regulations such as the Fire Service Act, and their storage volume is also limited.

As described above, the one-component solvent-type moisture-curable urethane-based adhesive has the speed and strength of initial tack and good adhesiveness, but in today's society, it is dangerous and harmful based on organic solvents. Is a significant drawback of this adhesive.

[0008] The means for solving the above problem is to eliminate the solvent, but it cannot be realized simply by reducing the amount of the organic solvent to zero. That is, the adhesive is required to develop a high initial tack as early as possible, but the urethane prepolymer used for the one-component moisture-curable urethane-based adhesive needs to be in a liquid state. When a prepolymer having the largest possible molecular weight is used, firstly, the coating operation is difficult, and secondly, since the high molecular weight polymer has poor wettability,
A technical difficulty arises in that no adhesive properties comparable to the solvent form can be obtained.

[0009] Actually, the conventional one-package, solvent-free, moisture-curable urethane-based adhesives have to use a low-molecular-weight prepolymer, so that they have poor initial tack and are slow to develop. Is pointed out. In addition, in order to provide coating workability, it is necessary to dilute with some organic solvent. In addition, in terms of adhesiveness, since the wettability is poorer than that of the solvent type, at present, both the adhesiveness and the adhesive strength are inferior to hard-to-adhere materials such as plastics.

[0010]

SUMMARY OF THE INVENTION The present invention improves the coating workability, which is a drawback of the conventional one-component, solvent-free, moisture-curable urethane-based adhesive, imparts excellent adhesiveness, and provides quick-curing. And to enable the early expression of good initial tack.

[0011]

Means for Solving the Problems The present inventors have been searching for a diluent having excellent dilutability for a moisture-curable adhesive using a urethane prepolymer in place of a conventional low-boiling to medium-boiling organic solvent. Was. As a result, N-methyl-2-pyrrolidone was found. According to a literature search, this diluent was found to be used as a solvent during the urethane polymerization together with dimethylformamide. However, it has been found that this diluent gives not only a diluting effect but also various unexpected properties.

That is, this diluent is
In addition to simply leading to a low viscosity, it has completely unknown effects such as imparting excellent adhesion to difficult-to-bond materials such as metals, rubbers, and plastics, and further having an effect of accelerating the curing speed. The discovery was the origin of the present invention.

The term "low viscosity" as used in the present invention refers to a range of viscosities that become liquid at room temperature, specifically, for example, a viscosity (23 ° C.) at a rotational speed of 20 r / min of a B-type viscometer.
Indicates 100 Pa · s or less.

When a specific urethane curing catalyst, bis (morpholinoethyl) ether, bis (2,6-dimethylmorpholinoethyl) ether or bis (3,5-dimethylmorpholinoethyl) ether, is used in combination, the above characteristics are obtained. It was found that the interaction had a significant effect of accelerating the curing rate while maintaining the above. Therefore, the curing speed is higher than when the specific urethane curing catalyst is used alone.

[0015] Thereafter, further studies were conducted with the aim of reducing the viscosity of the prepolymer and improving the balance of the adhesive function and improving the initial tack. For the technical means of using a polyol in combination with a specific polyester polyol, the rapid curing and the early onset of the resulting initial tack, the technical means of using a specific amine compound as a curing catalyst was discovered, and the object of the present invention was further improved. The present invention was completed by achieving some improvement.

Hereinafter, the technical means of the present invention will be specifically described. That is, the invention of claim 1 is a one-liquid coatable at room temperature, characterized in that N-methyl-2-pyrrolidone is blended with an isocyanate-terminated urethane prepolymer to obtain low viscosity and high adhesiveness. It is a moisture-curable urethane liquid type adhesive composition.

According to the second aspect of the present invention, the ratio of N-methyl-2-pyrrolidone to the isocyanate-terminated urethane prepolymer is 0.1 to 30 parts by mass with respect to 100 parts by mass of the prepolymer. 2. The one-component moisture-curable urethane-based liquid-type adhesive composition according to claim 1, wherein the adhesive has high viscosity and high adhesiveness.

According to a third aspect of the present invention, the isocyanate-terminated urethane prepolymer is a polyoxypropylene polyol, a polyester polyol obtained by a reaction of a polyhydric alcohol and a polycarboxylic acid, and an isocyanate obtained by a polyisocyanate. 3. A one-part, moisture-curable urethane-based liquid adhesive composition applicable at room temperature according to claim 1 or 2, wherein the balance of adhesion performance is improved with a low viscosity of a terminal urethane prepolymer. It is.

The invention according to claim 4 is directed to the one-component moisture-curable urethane liquid adhesive composition according to any one of claims 1 to 3, wherein bis (morpholinoethyl) ether and bis (2 1, 6-dimethylmorpholinoethyl) ether and bis (3,5-dimethylmorpholinoethyl) ether are blended with at least one amine compound, and have improved fast-curing properties, characterized in that they can be coated at room temperature. It is a liquid moisture-curable urethane liquid type adhesive composition.

The polyol which is a starting material of the urethane prepolymer of the present invention can be classified into a polyether polyol and a polyester polyol.

Examples of the polyether polyol include polyoxyalkylene diols (specifically, polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, and copolymers thereof), and polyoxyalkylene triols (specifically, Polyoxyalkylene polyols such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc. and glycerin, trimethylolpropane, etc.), and bisphenols, sugars, amines, etc., starting from ethylene oxide or propylene oxide. Examples thereof include added diols, polyether polyols, and polyoxytetramethyl glycol obtained by ring-opening polymerization of tetrahydrofuran.

Of these, polyoxyalkylene diols and polyoxyalkylene triols are preferably used because of their low viscosity and easy liquefaction.

As the polyester polyol, conventionally known polyester polyols can be widely used as long as they are compounds having a hydroxyl group at a terminal having an ester bond as a repeating unit. Specifically, a condensation-based polyester polyol obtained by dehydration condensation of a polyhydric carboxylic acid (mainly adipic acid or phthalic acid) and a polyhydric alcohol (specifically, glycol, triol, etc.); ring-opening polymerization of ε-caprolactone A lactone-based polyester polyol obtained by the method described above; a polycarbonate diol obtained by phosgenation of a polyol or a transesterification reaction with diphenylene carbonate; a polyester polyol obtained by a polyaddition reaction between a polycarboxylic anhydride and a diepoxide; Urethane-modified polyester polyols as introduced can be mentioned.

Among them, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol, and adipic acid, sebacic acid It is preferable to use a condensation polyester polyol obtained by a condensation reaction with a polycarboxylic acid such as isophthalic acid or trimellitic acid.

Other polyols include dihydric alcohols such as ethylene glycol, propylene glycol and 1,4-butanediol, polyhydric alcohols such as glycerin, trimethylolpropane and neopentyl glycol, and hydroxyl-terminated polybutadiene (1,2). -Adduct, 1,
4-adduct), a so-called rosin-modified polyol having a rosin skeleton in the molecule, an amine polyol having an amine structure in the molecule, and a so-called silicon in which carbinol is introduced into both ends of polysiloxane called a carbinol-modified silicone oil. Diols, so-called acrylic polyols having an acrylic acid ester (including methacrylic acid ester) as a skeleton, and a so-called fluorine having a hydroxyl group at a terminal of a fluorine resin (for example, a copolymer resin of ethylene difluoride and an acrylic type) as a skeleton. Resin-based polyols and the like can be mentioned.

As the polyisocyanate used in the present invention, an aliphatic, aromatic or alicyclic polyisocyanate compound having a plurality of, preferably an average of 2 to 3 isocyanate groups in a molecule is used.

Specifically, for example, 2,4-toluene diisocyanate (hereinafter, referred to as "2,4-TDI"),
2,6-toluene diisocyanate (hereinafter, referred to as “2,6-
TDI. " ), 2,4-TDI and 2,6-TDI
An isomer mixture of 4,4′-diphenylmethane diisocyanate (hereinafter, referred to as “4,4′-MDI”);
2,4'-diphenylmethane diisocyanate (hereinafter, referred to as
It is called "2,4'-MDI". ), An isomer mixture of 4,4′-MDI and 2,4′-MDI (trade name: Luplanate MI, manufactured by BSF Japan Ltd.), carbodiimide-modified MDI, polymethylene polyphenyl polyisocyanate (hereinafter, “polymeric MDI "), Hexamethylene diisocyanate (hereinafter referred to as" H
MDI ". ), Xylene diisocyanate (hereinafter referred to as “XDI”), meta-xylene diisocyanate, 1,5-naphthalenediisocyanate, hydrogenated M
Isocyanate compounds such as DI, hydrogenated TDI, hydrogenated XDI, and isophorone diisocyanate;
Burette polyisocyanate compounds such as (manufactured by Sumitomo Bayer Urethane Co.); polyisocyanate compounds having an isocyanate ring such as Desmodur IL, HL (manufactured by Bayer AG) and Coronate EH (manufactured by Nippon Polyurethane Industry); Sumidule L (Sumitomo Bayer Urethane), Coronate HL (Nippon Polyurethane Industry)
And the like.

Among them, 4,4'-MDI and their crude products, a mixture of 4,4'-MDI and 2,4'-MDI and their crude products are used to obtain the initial tack strength, It is preferable in terms of adhesiveness, adhesive strength, and good application work.

The isocyanate-terminated urethane prepolymer is usually selected from polyether polyols, polyester polyols, and other polyols.
It is synthesized by allowing an excess of polyisocyanate to act on a mixed polyol obtained by a combination of two or more kinds.

The term "excess polyisocyanate" as used herein means that the chemical equivalent of the isocyanate group is in excess of the chemical equivalent of the hydroxyl group of all the polyol components, and the relationship of the chemical equivalent is expressed by the NCO / OH ratio. it can. That is, theoretically, if the NCO / OH ratio exceeds 1, the terminal may be an isocyanate terminal, but since the present invention is characterized by being liquid, the NCO / OH ratio is usually preferably 1.5 or more. Although the upper limit of the NCO / OH ratio is not particularly limited, the NCO / OH ratio is preferably 10.0 or less in consideration of adverse effects such as delayed curing and increased foaming during moisture curing. Particularly for leading to liquid, low viscosity prepolymers,
It is particularly preferable to adjust the NCO / OH ratio to about 1.5 to 8.0 while considering the type, the number of functional groups, and the molecular weight of the polyol.

Although the polymerization temperature and the polymerization time are not particularly limited, it is usually preferable to mix the polyol and the polyisocyanate under a stream of nitrogen gas and then react at 50 to 100 ° C. for 3 to 8 hours.

N-methyl-2-pyrrolidone used in the present invention may be a commercially available product as it is, but in order to obtain long-term storage stability, water was removed with a commercially available dehydrating agent such as molecular sieve or silica gel. Is more preferred.

The amount of N-methyl-2-pyrrolidone used in the present invention is 0.1 to 100 parts by mass of the prepolymer.
1 to 30 parts by mass is preferred. If the amount is less than 0.1 part by mass, the viscosity of the adhesive is reduced, and it is difficult to impart an adhesive property to a difficult-to-adhere material. The effect of N-methyl-2-pyrrolidone is essentially not exhibited, such as the effect of developing the initial tack is weakened and it is difficult to secure the adhesive strength for the next operation. The most preferable range of the amount of N-methyl-2-pyrrolidone that exerts the above effects most remarkably is 0.5 to 30 parts by mass.

When it is incorporated into the adhesive of the present invention, it may be incorporated at any time during the urethane prepolymer synthesis process and the adhesive manufacturing process. However, N-methyl-2-pyrrolidone is likely to absorb water. Therefore, it is more preferable during the production process of the adhesive which is less affected by moisture. Most preferably, it is blended in the final production step of the adhesive.

The polyoxypropylene diol of the polyoxypropylene polyol in the present invention is synthesized by addition polymerization of propylene oxide using propylene glycol, neopentyl glycol or the like as an initiator.
Polyoxypropylene triol is synthesized by addition polymerization of propylene oxide using glycerin or trimethylolpropane as an initiator. These generally have a molecular weight of 400 to 20,000.

The polyester polyols obtained by the reaction between the polyhydric alcohol and the polycarboxylic acid in the present invention are, for example, polyester polyols obtained by the condensation reaction of propylene glycol and adipic acid (trade name) : Adecan New Ace F7-68, molecular weight 1000, bifunctional, manufactured by Asahi Denka Kogyo Co., Ltd.) or a polyester polyol obtained by a condensation reaction between diethylene glycol and adipic acid (trade name: Adecan New Ace F)
15-22, molecular weight 2,000, bifunctional, manufactured by Asahi Denka Kogyo Co., Ltd.).

The bis (morpholinoethyl) ether, bis (2,6-dimethylmorpholinoethyl) ether and bis (3,5-dimethylmorpholinoethyl) ether of the present invention are represented by the following general formula 1.

[0038]

Embedded image

Wherein R ² is a C ₁ -C ₃ alkyl group, n
Represents an integer of 0 to 4, and this compound represented by this formula is a urethane curing catalyst.

These bis (morpholinoethyl) ethers are so-called foam type amine catalysts which have excellent storage stability and promote the reaction between isocyanate groups and moisture suitable for the production of urethane foam. Since it has excellent storage stability as well as production, it is a general urethane polymerization catalyst used for many uses such as caulking materials such as urethane sealants.

The mixing ratio of the urethane curing catalyst is 0.05 to 10 with respect to 100 parts by mass of the urethane prepolymer.
Parts by weight. If the amount is less than 0.05 part by mass, the effect of promoting the curing by interaction with N-methyl-2-pyrrolidone is poor. If the amount is more than 10 parts by mass, the storage stability such as an increase in viscosity of the adhesive over time becomes extremely poor.

The curing catalyst may be used in combination with other amine-based urethane catalysts and organometallic-based urethane catalysts such as dibutyltin dilaurate according to the purpose.

The manufacturing process of the adhesive of the present invention will be described below. In the manufacturing process, an inorganic filler, a thixotropic agent, a plasticizer, a diluent, a tackifier resin, an adhesion promoter, a curing catalyst, It is manufactured by mixing and processing various modifiers such as a moisture binder, a stabilizer, a colorant, and an organic solvent.

Since this adhesive is destabilized by the influence of moisture during the manufacturing process and during storage, it is necessary to remove as much moisture as possible from the raw materials containing moisture in the compounding raw material, in order to improve the stability of the quality of the adhesive over a long period of time. It is preferable for obtaining.

Examples of the inorganic filler used in the present invention include inorganic fillers such as calcium carbonate, clay, talc, magnesium oxide, diatomaceous earth and glass balloons which can be industrially used as fillers. Can be used.

Examples of the thixotropic agent include ultrafine powdered silica and hardened castor oil.

Examples of the plasticizer include dioctyl phthalate, dibutyl phthalate, dilauryl phthalate,
Butylbenzyl phthalate, dioctyl adipate, diisodecyl adipate, trioctyl phosphate,
Mineral spirit and the like can be mentioned, and each can be used alone or in combination.

As the diluent, petroleum hydrocarbon diluent,
Esters such as 3-methyl-3-methoxybutyl acetate and dimethyl glutarate.

As the tackifying resin, a conventionally known resin can be used. Specifically, for example, in the case of natural resin-based tackifying resins, rosin-based resins such as rosin, modified rosin, and rosin ester; and terpene-based resins such as terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, and terpene phenol resin are used. is there. In the synthetic resin-based tackifying resins, aliphatic (C ₅ series) petroleum resin, aromatic (C ₉
System) petroleum resins, copolymeric (C ₅ / C ₉ series) petroleum resin, hydrogenated petroleum resins, petroleum resins such as DCPD petroleum resin; coumarone-indene resins; pure monomer systems such as styrene resin or a substituted styrene resin Petroleum resins; phenolic resins such as alkylphenol resins and rosin-modified phenolic resins; xylene resins;

Among them, a tackifying resin which is liquid at normal temperature and a tackifying resin which can be dissolved in a urethane prepolymer when solid can be used, and a solid resin having a softening point of preferably 130
It is below ° C.

Examples of the adhesion-imparting agent include a silane coupling agent (γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, a reaction product of both compounds, and the like).

Examples of the water binder include tosyl isocyanate and zeolite.

As stabilizers, tinuvin 326, 2,4
An ultraviolet absorber such as dihydroxybenzophenone, Zn
And metal chelates such as Ni-dibutyldithiocarbamate, and azo compounds such as p-hydroxyazobenzene and p-aminoazobenzene. These are used for the purpose of light stabilization.

Examples of the colorant include inorganic colorants such as titanium oxide, iron oxide, chromium oxide, cadmium sulfate, aluminomagnesium, and lamp black; azo and diazo dyes;
Organic dyes such as phthalocyanine and dioxazine are exemplified. Although the organic solvent is not required in the present invention, it does not prevent its use.

[0055]

DETAILED DESCRIPTION OF THE INVENTION A urethane prepolymer is synthesized,
After being transferred to another device, it is processed into adhesive, or with one device,
Whether to use both the urethane prepolymer synthesis and the processing into the adhesive can be appropriately selected, but here, the embodiment will be described by the former method.

According to the first aspect of the present invention, in order to improve the adhesion of the urethane prepolymer having an isocyanate group end, N
-Methyl-2-pyrrolidone.

The polyol is charged into a reaction vessel, sufficiently dehydrated under reduced pressure, mixed with an excess of polyisocyanate such as 4,4'-diphenylmethane diisocyanate or a crude product thereof, and subjected to usual urethane synthesis conditions (for example, at 80 ° C. for 4 hours). ). After cooling, N-methyl-2-pyrrolidone is blended to obtain an adhesive. At this time, another modifier not affected by moisture (specifically, calcium carbonate, dioctyl phthalate, ultrafine powdered silica, etc.) may be blended.

According to the second aspect of the present invention, the compounding ratio of N-methyl-2-pyrrolidone to the isocyanate group-terminated urethane prepolymer for further lowering the viscosity and increasing the adhesion in the first aspect of the present invention is as follows: It is 0.1 to 30 parts by mass based on 100 parts by mass of the prepolymer.

The third and fourth embodiments of the present invention are as follows. The polyether polyol and the polyester polyol may be used alone. However, a prepolymer having low viscosity and excellent adhesiveness can be obtained when used in combination. Polyoxypropylene polyol as the polyether polyol, and at least one of the hydroxyl-terminated polyols obtained by esterifying adipic acid and ethylene glycol as the polyester polyol are charged into the reaction apparatus,
After sufficient dehydration under reduced pressure, an excess amount of polyisocyanate such as 4,4'-diphenylmethane diisocyanate or a crude product thereof is added thereto, and the mixture is subjected to ordinary urethane synthesis conditions (for example, 80 ° C).
For 4 hours). After cooling, N-methyl-2-pyrrolidone is blended to obtain an adhesive. At this time, another modifier not affected by moisture (specifically, calcium carbonate, dioctyl phthalate, ultrafine silica powder, etc.) may be blended.

Further, in order to make the adhesive obtained above more curable, bis (morpholinoethyl) ether,
Bis (2,6-dimethylmorpholinoethyl) ether,
A urethane curing catalyst selected from bis (3,5-dimethylmorpholinoethyl) ether may be blended.

The adhesive thus obtained is housed in a hermetically sealable container such as a cartridge or a pail under a nitrogen stream. After storage, the adhesive is taken out by a method such as squeezing out or removing a spatula, and applied to the adherend. The application method is appropriately selected according to the procedure of the bonding operation. Usually, it is applied using a comb-shaped iron.

[0062]

EXAMPLES Hereinafter, examples will be described based on the embodiments of the present invention in order to more specifically illustrate the present invention.

Example 1 300 parts by mass of a bifunctional polypropylene glycol having a molecular weight of 2,000 (Takelac P-21: trade name, manufactured by Takeda Pharmaceutical Co., Ltd.) and a trifunctional polypropylene glycol having a molecular weight of 3,000 (Takelac P, trade name) were placed in a 1 L separable flask. -31, manufactured by Takeda Pharmaceutical Company Limited) 10
0 parts by mass, 100 parts by mass of a bifunctional polyester-based polyol having a molecular weight of 2,000 (trade name: ADEKA NUACE F7-67, manufactured by Asahi Denka Kogyo Co., Ltd.), and after dehydration under reduced pressure at 100 ° C. for 1 hour, to room temperature. After cooling, when the liquid temperature dropped to 50 ° C., Crude MDI (trade name: Sumidur 4)
(4V-20, manufactured by Sumitomo Bayern Urethane Co., Ltd.) (250 parts by mass) was added and reacted at 80 ° C. for 4 hours to obtain a urethane prepolymer. 750 parts by mass of this prepolymer was transferred to a 5 L planetary mixer, and sufficiently dried heavy calcium carbonate (trade name: NS # 2300, manufactured by Nitto Powder Chemical Co., Ltd.)
00 parts by mass, 50 parts by mass of fine powder silica (trade name: RY200, manufactured by Nippon Aerosil Co., Ltd.) and 200 parts by mass of DOP were added and mixed well. N-methyl-2-pyrrolidone (75 parts by mass) was added to obtain a solvent-free, low-viscosity, one-component moisture-curable urethane liquid adhesive composition.

Example 2 In the last step of the adhesive of Example 1, 5 parts by mass of bis (2,6-dimethylmorpholinoethyl) ether (trade name: U-CAT2041, manufactured by San Apro Co.) was blended. The viscosity value was almost the same as in Example 1.

Comparative Example 1 The adhesive of Example 1 did not contain N-methyl-2-pyrrolidone (NMP) in the final step.

Comparative Example 2 The procedure of Example 1 was followed, except that a petroleum hydrocarbon solvent (Shellsol 71, manufactured by Shell Japan) was used instead of NMP.

[0067]

[Table 1]

Comparative Example 3 The procedure of Example 2 was followed except that a petroleum hydrocarbon solvent (trade name: Shellsol 71, manufactured by Shell Japan) was used instead of NMP.

Table 1 shows the compositions of Examples 1 and 2 and Comparative Examples 1, 2, and 3.

The one-part moisture-curable urethane-based adhesive composition thus obtained was evaluated for coating workability (viscosity and viscosity), adhesiveness, and quick-curing property by the following methods.

The coating workability (viscosity and viscosity) is determined by the viscosity and viscosity of the composition (thixotropic index; hereinafter,
It is called "TI value". ) Was evaluated. That is, the viscosity (23 ° C.) at a rotation speed of 20 r / min and 2 r / min of a B-type rotational viscometer was measured, and further measured at 2 r / min / 20.
r / min = TI value was calculated. Further, practical application workability was evaluated by lightness of ironing when actually applying with a trowel. The evaluation was made in three stages of ○, Δ, and ×.
Here, ○ means good, Δ means good, × means bad, and × means not practical. Also, the TI value is an index of the quality of the coating workability, and the larger the value, the better the coating workability such as ironing.

Adhesion: 22 ± 1 ° C., 55 ± 5% RH
8mm thick flexible board and 1.5mm thick, 25mm wide, 150mm long indoors adjusted to (standard conditions)
mm flexible PVC sheet and the above adhesive composition were allowed to stand from the previous day, and were applied to a fibrous board with a comb-shaped iron so that the coating amount was about 250 g / m ² . After laminating PVC sheets for 3 days,
The peel strength at 90 degrees was measured at a pulling speed of 50 mm / min, and the bond strength at that time and the breaking state were compared. If the position of the break is the adhesive layer, the adhesiveness to the adherend is good, but if it is at the interface between the adherend and the adhesive, the adhesiveness can be judged to be poor.

The quick-curing property was evaluated by the time until tack-free.

That is, the adhesive composition was applied under the same conditions as in the evaluation of the adhesiveness, and the time until tack was not felt by touching the finger (tack free time) was determined. The shorter the tack-free time, the faster the curing.

Table 2 shows the evaluation results of the coating workability, adhesiveness, and quick-curing property.

From the results shown in Table 2, in Examples, the viscosity was low in both Examples 1 and 2, and the TI value, which is an index representing the structural viscosity, which is the viscosity ratio of 2 r / min to 20 r / min, was large. Workability was good. In Comparative Example 1, the viscosity was very high, the ironing was very heavy, and the coating operation was not practical. In Comparative Examples 2 and 3, a low viscosity was obtained and a relatively large TI value was obtained, but the adhesion was much insufficient, and particularly in Comparative Example 2, the tack tally time was long.

[0077]

[Table 2]

As a result of the adhesiveness, all of the examples were 20
While the adhesive strength exceeding 00 N / m was developed, the adhesive strength of Comparative Example 1 having a high viscosity exhibited about half of that, but the adhesive strengths of Comparative Examples 2 and 3 were further reduced. The position of the break was also the interface between the soft PVC sheet and the flexible board, resulting in poor adhesion.

The time until tack-free in which the quick-curing property was observed was as short as 30 to 50 minutes in the examples, and the fast-curing property was as good as that of the solvent type.

On the other hand, in Comparative Examples 1 and 2,
It took 80 to 90 minutes before tack-free, and was inferior in fast-curing properties. Further, in Comparative Example 3, although the time required to become tack-free due to the effect of the catalyst was shortened, good adhesion was not obtained as in the other Comparative Examples.

[0081]

As described above, the one-component moisture-curable urethane-based liquid adhesive composition of the present invention can be used as a solventless adhesive containing no low- or medium-boiling organic solvent. Compared to the conventional solvent-free, one-component moisture-curable urethane-based adhesive, a low-viscosity adhesive composition is obtained, and it exhibits excellent structural workability at room temperature, such as a comb-shaped ironing iron. The coating operation can be easily performed. As for the bonding work, it has fast curing properties and good bonding strength.
In particular, it exhibits excellent adhesion to hard-to-bond materials such as metal, rubber, and plastic.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 18/48 C08G 18/48 Z

Claims (4)

[Claims] 1. A one-part, moisture-curable urethane-based liquid-type adhesive characterized by having low viscosity and high adhesiveness by mixing N-methyl-2-pyrrolidone with an isocyanate-terminated urethane prepolymer. Composition. 2. The mixing ratio of N-methyl-2-pyrrolidone to the isocyanate-terminated urethane prepolymer is 0.1 to 30 parts by weight per 100 parts by mass of the prepolymer.
The one-component moisture-curable urethane-based liquid-type adhesive composition according to claim 1, characterized in that it has low viscosity and high adhesiveness in terms of parts by mass. 3. The isocyanate-terminated urethane prepolymer is a polyoxypropylene polyol, an isocyanate-terminated urethane prepolymer obtained from a polyisocyanate and a polyester polyol obtained by a reaction between a polyhydric alcohol and a polycarboxylic acid. The one-component moisture-curable urethane-based liquid-type adhesive composition according to claim 1, wherein the one-component moisture-curable urethane-based liquid-type adhesive composition has a low viscosity and an excellent balance of an adhesive function. 4. The one-component moisture-curable urethane-based liquid adhesive composition according to claim 1, wherein bis (morpholinoethyl) ether and bis (2,6-dimethylmorpholinoethyl) are used. A one-pack moisture-curable urethane-based liquid-type adhesive composition characterized by having high curability obtained by blending at least one amine compound selected from ether and bis (3,5-dimethylmorpholinoethyl) ether. .