JP2003201460A - Solvent-free moisture-curing adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solvent-free, moisture-curable adhesive having good storage stability and weather resistance, and particularly having a low odor during bonding. SOLUTION: This is a solvent-free moisture-curing adhesive comprising (A) an organic polyisocyanate and (B) an isocyanate group-containing prepolymer obtained by reacting an active hydrogen group-containing compound, wherein the (A) organic polyisocyanate is used. Is (A1) hexamethylene diisocyanate and (A
2) An alkyl monool having 1 to 10 carbon atoms is converted into (A)
3) Solved by a solventless moisture-curing adhesive characterized by being a polyisocyanate obtained by allophanation in the presence of a zirconium carboxylate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solventless moisture-curing adhesive. More specifically, the present invention relates to a solvent-free moisture-curing adhesive which has good storage stability, weather resistance and the like, and particularly has little odor during bonding work.

[0002]

2. Description of the Related Art Polyurethane-based adhesives that have been widely used in the adhesive field are roughly classified into the following three types according to the curing mechanism. The first is a two-component polyurethane-based adhesive that mixes the main agent and the curing agent immediately before use, applies the mixture to an adherend and cures it. The second is a moisture-curable polyurethane adhesive that uses an isocyanate group-containing prepolymer and reacts with the active hydrogen groups of the substrate and moisture in the atmosphere to cure. This system develops initial adhesive force by melting and coating at a high temperature of 100 ° C or more, and solidifying by cooling, and then reacts with active hydrogen groups of the base material and moisture in the atmosphere to polymerize and crosslink. Also included are solventless reactive hot melt adhesives that cure with. Thirdly, a solution in which a high molecular weight thermoplastic polyurethane resin is dissolved or dispersed in a solvent or water is applied to an adherend, and an adhesive layer is formed with a high molecular weight polyurethane resin having a large cohesive energy only in the process of scattering the solvent or water. It is a so-called one-pack type lacquer type polyurethane adhesive that exhibits adhesive strength.

Two-component polyurethane adhesives are generally excellent in heat resistance and durability because they have a crosslinked structure in the adhesive layer. However, the two-component compounded liquid has a limited pot life because it thickens due to the reaction between the isocyanate group and the active hydrogen group in the system and finally gels. In addition, it is necessary to pay sufficient attention to the mixing ratio of the two components. The one-pack type lacquer type polyurethane adhesive is a solution of a high molecular weight polyurethane resin, has a semi-permanent pot life as long as the solvent or the like is not scattered, and has excellent workability. However, since the adhesive layer does not have a cross-linking structure, it is thermoplastic and has a low softening point, and when the softening temperature is exceeded, the adhesive strength decreases. That is, it has a defect of poor heat resistance.

On the other hand, the moisture-curable polyurethane adhesive is usually a two-component polyurethane adhesive because the adhesiveness of the two-component polyurethane-based adhesive usually undergoes a step of reacting with the base material or moisture in the air to cure. However, it is superior to the one-pack lacquer type in heat resistance. This moisture-curable polyurethane-based adhesive is obtained by prepolymerizing an active hydrogen group-containing compound and a polyisocyanate monomer in an atmosphere of excess isocyanate groups,
It will contain unreacted polyisocyanate monomer. For this reason, the work environment is deteriorated depending on the conditions at the time of applying the adhesive, and thus it is often necessary to install a local exhaust device or the like. In addition, there is a problem of poor appearance due to unreacted polyisocyanate monomer (e.g., generation of floating matters and precipitates) over time.

Various proposals have been made for improving these polyurethane adhesives. For example, a method of adding a polyisocyanate curing agent to a one-pack type lacquer type polyurethane adhesive (two-pack type) has been proposed. In addition, for a two-component polyurethane adhesive, a method has been proposed in which a blocked isocyanate is used to make it apparently one component. However, the former method still requires that the pot life be limited and that the formulation be accurate. In the latter method, problems such as pollution problems due to foaming of the adhesive layer due to the blocking agent and scattering of the blocking agent or reduction of adhesive strength due to the residual blocking agent remain,
It is used in some applications as a one-component paint system in the paints field, but is rarely used in the adhesives field.

[0006] In the field of moisture-curable polyurethane adhesives, formulations that are not significantly affected by external conditions such as introduction of a water-absorbing composition and addition of catalysts, and curing agents and isocyanates that generate amino groups due to moisture such as ketimine / aldimine compounds. An apparent one-component composition using a group-containing prepolymer system has been proposed. However, in any case, a complete one-component adhesive having long-term storability has not yet been developed, and its development is now strongly desired.

Further, due to environmental problems on a global scale, VOC (Volatile Organic Compound) regulations for controlling the scattering of solvents and the like, and movements demanding resource saving, low pollution, and safety are prominent. From a viewpoint, high solid type,
Attention has been focused on solventless powders (including hot melts) and water-based adhesives.

[0008] Allophanate group-containing polyisocyanates are known, and as a technique for using them in the adhesive field, JP-A-6-41270 and JP-A-11-322 are known.
879, etc. The allophanate group-containing polyisocyanate used in these techniques contains isocyanurate groups and uretdione groups. this is,
This is because a considerable amount of isocyanurate-forming reaction and uretdione-forming reaction are performed in parallel as side reactions of the allophanate-forming reaction. Since the isocyanurate group is trifunctional, prepolymerization using a polyisocyanate containing this may cause gelation if the molecular weight is increased. Further, when trying to avoid gelation, the molecular weight cannot be made high, so the resulting adhesive has insufficient adhesive strength due to insufficient molecular weight, or insufficient flexibility or brittleness of the adhesive layer due to insufficient soft segment introduction. There's a problem. Furthermore, since the uretdione group has poor heat resistance and is easily dissociated with time, the uretdione group-containing polyisocyanate is anxious about storage stability.

[0009]

The present invention has been made to solve the above-mentioned problems, and by using an allophanate group-containing polyisocyanate manufactured by a specific manufacturing method, storage stability, weather resistance, etc. Is good,
In particular, it is an object of the present invention to provide a solvent-free moisture-curing adhesive which has little odor during the bonding work.

[0010]

That is, the present invention is shown in the following (1) to (3). (1) (A)
A solventless moisture-curing adhesive comprising an isocyanate group-containing prepolymer obtained by reacting an organic polyisocyanate and (B) an active hydrogen group-containing compound, wherein the (A) organic polyisocyanate is (A1) hexamethylene. Solvent-free, moisture-curing adhesive, which is a polyisocyanate obtained by allophanating diisocyanate and (A2) alkyl monool having 1 to 10 carbon atoms in the presence of (A3) zirconium carboxylic acid salt. Agent.

(2) The solventless moisture-curing adhesive according to (1) above, wherein the content of unreacted hexamethylene diisocyanate is 0.5% by mass or less.

(3) Isocyanate content of 1 to 5% by mass
The solventless moisture-curing adhesive according to (1) or (2) above.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The solventless moisture-curing adhesive of the present invention is an isocyanate group-containing prepolymer obtained by reacting (A) an organic polyisocyanate and (B) an active hydrogen group-containing compound, The organic polyisocyanate (A) comprises (A1) hexamethylene diisocyanate and (A2) an alkyl monool having 1 to 10 carbon atoms,
3) A polyisocyanate obtained by allophanating in the presence of a carboxylic acid zirconium salt.

The diisocyanate used to obtain the (A) organic polyisocyanate is (A1) hexamethylene diisocyanate (hereinafter abbreviated as HDI).
Aromatic diisocyanates are not suitable for the present invention because the allophanate groups readily dissociate with heat. Since the alicyclic diisocyanate usually has a higher vapor pressure than HDI, it is difficult to remove unreacted diisocyanate monomer after the allophanatization reaction.

(A2) C1-C10 alkyl monool means methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, n-hexanol. And a compound having a hydroxyl group bonded to a linear alkyl group having 1 to 10 carbon atoms or having a side chain.

The (A3) carboxylic acid zirconium salt is an allophanatization catalyst. When an allophanatization catalyst other than the carboxylic acid zirconium salt is used, an isocyanurate-forming reaction as a side reaction during the allophanatization reaction,
It was found that a considerable amount of uretdione formation reaction occurred, but that side reactions hardly occurred with the carboxylic acid zirconium salt. Therefore, as the organic polyisocyanate (A) used in the present invention, an allophanate group-containing polyisocyanate obtained in the presence of a carboxylic acid zirconium salt is used. Examples of the carboxylic acid in (A3) include saturated aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and 2-ethylhexanoic acid.
Saturated monocyclic carboxylic acids such as cyclohexanecarboxylic acid and cyclopentanecarboxylic acid, saturated bicyclic carboxylic acids such as bicyclo (4.4.0) decane-2-carboxylic acid, mixtures of the above carboxylic acids such as naphthenic acid, olein Unsaturated carboxylic acids such as acids, linoleic acid, linolenic acid, soybean oil fatty acids and tall oil fatty acids, araliphatic carboxylic acids such as diphenylacetic acid, benzoic acid, monocarboxylic acids such as aromatic carboxylic acids such as toluic acid , Phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, curtaconic acid, azelaic acid, sebacic acid, succinic acid, adipine Acid, sebacic acid, azelaic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuco Acid, β- Haidoromukon acid, α
Examples thereof include polycarboxylic acids such as -butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid and pyromellitic acid. These zirconium carboxylic acid salts may be used alone or in the form of a mixture of two or more kinds. Preferred (A3) in the present invention is a monocarboxylic acid zirconium salt having 10 or less carbon atoms.

To obtain (A) used in the present invention, the following procedure is used. First, (A1) HDI
And (A2) an alkyl monool having 1 to 10 carbon atoms,
After charging an excess amount of isocyanate groups with respect to hydroxyl groups and carrying out a urethanization reaction at 20 to 100 ° C., 70 to
An allophanatization reaction is carried out at 150 ° C. in the presence of the zirconium salt of (A3) carboxylic acid until urethane groups are substantially absent.

Here, the molar ratio of the isocyanate group and the hydroxyl group at the time of charging the raw materials is preferably isocyanate group / hydroxyl group = 8 or more, and particularly preferably 10 to 50.

The reaction temperature for the urethanization reaction is 20 to 120.
C., preferably 50 to 100.degree. In the urethanization reaction, a known so-called urethanization catalyst can be used. Specific examples thereof include organic metal compounds such as dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof.

The reaction time for the urethanization reaction varies depending on the presence or absence of a catalyst, the type, and the reaction temperature, but is generally 10 hours or less, preferably 1 to 5 hours.

After the urethanization reaction is completed, the allophanatization reaction is carried out. The allophanate-forming reaction is carried out by adding the above-mentioned (A3) and adjusting the reaction temperature to 70 to 150 ° C, preferably 80 to 130 ° C. If the reaction temperature is too low, allophanate groups will not be generated so much, and the average number of functional groups of the resulting polyisocyanate composition will decrease. When such a polyisocyanate is used, the adhesive strength tends to be insufficient. When the reaction temperature is too high, the polyisocyanate may be colored and a side reaction may occur in a considerable amount. The average number of functional groups of polyisocyanate is the average number of isocyanate groups present in one molecule.

The urethanization reaction and the allophanate reaction can be carried out at the same time. In this case, (A1)
HDI and (A2) alkyl monool were charged in an amount such that the isocyanate group was in excess of the hydroxyl group, and 70 to 1
The urethanization reaction and allophanate reaction are carried out simultaneously at 50 ° C. in the presence of (A3) carboxylic acid zirconium salt.

The amount of the (A3) zirconium carboxylic acid used varies depending on the kind, but the above (A1) and (A2) are used.
0.0005 to 1% by mass is preferable, and 0.001 to 0.1% by mass is more preferable. When the amount of the catalyst used is less than 0.0005% by mass, the reaction is substantially delayed and it takes a long time, and coloring due to heat history may occur. On the other hand, when the amount of the catalyst used exceeds 1% by mass, it becomes difficult to control the reaction, and a side reaction such as a dimerization reaction (uretdione formation reaction) or a trimerization reaction (isocyanurate formation reaction).
May occur.

The reaction time for allophanate formation varies depending on the type and amount of catalyst added and the reaction temperature, but is usually 10 hours or less, preferably 1 to 5 hours.

In the reaction, an organic solvent can be used if necessary, but it is preferable to use no organic solvent because it will be removed later. As an organic solvent,
Aliphatic hydrocarbon organic solvents such as n-hexane and octane, alicyclic hydrocarbon organic solvents such as cyclohexane and methylcyclohexane, acetone, methyl ethyl ketone,
Ketone-based organic solvents such as methyl isobutyl ketone and cyclohexanone, ester-based organic solvents such as methyl acetate, ethyl acetate, butyl acetate and isobutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl Glycol ether ester type organic solvents such as acetate and ethyl-3-ethoxypropionate, ether type organic solvents such as diethyl ether, tetrahydrofuran and dioxane, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl bromide and iodide. Halogenated aliphatic hydrocarbon organic solvents such as methylene and dichloroethane,
Examples include polar aprotic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and hexamethylphosphonylamide.

After the allophanatization reaction, a catalyst poison is added to stop the allophanatization reaction. The addition timing of the catalyst poison is not particularly limited as long as it is after the allophanate-forming reaction, but when thin film distillation is performed as a method for removing unreacted HDI, the catalyst poison is added after the allophanate reaction and before the thin film distillation. Is preferably performed. This is to prevent side reactions from occurring due to heat during thin film distillation.

As the catalyst poison, known substances such as inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having a sulfonic acid group, a sulfamic acid group and the like, esters thereof, acyl halides and the like can be used.

The amount of the catalyst poison added varies depending on the type and type of the catalyst, but is preferably 0.5 to 2 equivalents of the catalyst, and particularly preferably 0.8 to 1.5 equivalents. If the catalyst poison is too small, the storage stability of the resulting polyisocyanate tends to decrease. If too much, the resulting polyisocyanate may be colored.

Then, unreacted HDI is removed. The removing method is not particularly limited, and examples thereof include distillation, extraction, and reprecipitation. The (A) organic polyisocyanate used in the present invention is preferably obtained by a thin film distillation method. The unreacted HDI content in (A) after removal is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. The unreacted HDI content is determined by gel permeation chromatography (GPC), and the calibration curve shows HDI as a simple substance as well as a dimer (monouretdione body) and trimer (diuretdione body, isocyanurate body). It is preferable to use a mixture of multimers such as).

The thus-obtained (A) has an isocyanate content of 17 to 22.8% and an average number of functional groups of 1.8 to 2.2. Viscosity at 25 ℃ is 200mPa
・ S or less. The average number of functional groups is calculated from the isocyanate content and the (number average) molecular weight. The number average molecular weight is determined by GPC, and the calibration curve is preferably HDI or a mixture of HDI multimers (dimer, trimer ...).

The active hydrogen group-containing compound (B) used in the present invention includes a so-called polymer polyol having a number average molecular weight of 500 to 10,000 and a chain extender having a (number average) molecular weight of less than 500. .

Examples of the polymer polyols include polyester polyols, polyester amide polyols, polycarbonate polyols, polyether polyols, polyolefin polyols, animal / vegetable polyols, and copolyols thereof. You may use these high molecular polyols individually or in mixture of 2 or more types.

As the polyester polyol and polyester amide polyol, at least one of the above-mentioned known polycarboxylic acids (including acid ester and acid anhydride derived from polycarboxylic acid), ethylene glycol, and 1,2-
Propanediol, 1,3-Propanediol, 1,2
-Butanediol, 1,3-butanediol, 1,4-
Butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-
Pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 2,2-diethyl-1,3-propane Diol,
2-n-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-n-
Hexadecane-1,2-ethylene glycol, 2-n-
Eicosane-1,2-ethylene glycol, 2-n-octacosane-1,2-ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, or ethylene oxide or propylene oxide adduct of bisphenol A, hydrogenation Bisphenol A, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropionate, trimethylolpropane, glycerin,
Obtained by dehydration condensation reaction with low molecular weight polyols such as pentaerythritol, low molecular weight polyamines such as hexamethylenediamine, xylylenediamine and isophoronediamine, and low molecular weight amino alcohols such as monoethanolamine and diethanolamine. There are things. Further, a low molecular weight polyol, a low molecular weight polyamine, or a low molecular weight amino alcohol as an initiator is used as a cyclic ester (lactone) such as ε-caprolactone or γ-valerolactone.
Examples thereof include lactone-based polyester polyols obtained by ring-opening polymerization of monomers.

Examples of the polycarbonate polyols include those obtained by dealcoholation reaction and dephenolation reaction of the low molecular weight polyol used for the synthesis of the above-mentioned polyester polyol with diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate and the like. To be

As the polyether polyol, a polyethylene glycol obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran or the like with a low molecular weight polyol, a low molecular weight polyamine or a low molecular weight amino alcohol used as the above-mentioned polyester polyol as an initiator, Examples thereof include polypropylene glycol, polytetramethylene ether glycol and the like, and polyether polyols obtained by copolymerizing these, and further polyester ether polyols using the above-mentioned polyester polyol and polycarbonate polyol as an initiator.

Examples of the polyolefin polyols include hydroxyl group-containing polybutadiene, hydrogenated hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisoprene, hydrogenated hydroxyl group-containing polyisoprene, hydroxyl group-containing chlorinated polypropylene and hydroxyl group-containing chlorinated polyethylene.

The animal and plant polyols include castor oil-based polyols, silk fibroin and the like.

Incidentally, urea resin, melamine resin, epoxy resin, polyester resin, acrylic resin, polyvinyl alcohol, rosin resin and the like are generally known in the polyurethane industry and have a functional group capable of reacting with an isocyanate group such as an active hydrogen group. As long as it contains one or more, preferably two or more, it can be used as all or a part of the active hydrogen group-containing compound.

Examples of the chain extender include low molecular weight polyols, low molecular weight polyamines, low molecular weight amino alcohols, water and urea which are raw materials of the above polyester polyol.

The method for producing the solventless moisture-curing adhesive of the present invention is a method of reacting the above (A) and (B). As a specific reaction procedure, for example, a method of reacting (A) and (B) little by little at once, first (A)
In the method (B), a polymer polyol is first reacted, and then a chain extender is reacted.

The reaction temperature and reaction time of (A) and (B) are
It is based on the urethanization reaction for obtaining the above (A). In addition, the molar ratio of the isocyanate group and the active hydrogen group in the charging of (A) and (B) is preferably isocyanate group / active hydrogen group = 1.1 to 10, particularly preferably 1.2 to 5. Further, it is preferable to use the above-mentioned urethanization catalyst in the reaction.

As the reaction device, any device may be used as long as the above reaction can be achieved, and examples thereof include a reaction kneader equipped with a stirring device, a kneader, and a mixing and kneading device such as a uniaxial or multiaxial extrusion reactor.

The isocyanate content of the solventless moisture-curing adhesive thus obtained is preferably 1 to 5% by mass, and more preferably 1.2 to 4.8% by mass. When the isocyanate content is less than 1% by mass, the molecular weight of the prepolymer is too large and the viscosity becomes large, resulting in poor workability. If it exceeds 5% by mass, the molecular weight of the prepolymer is too small and mechanical strength is not exhibited.

The viscosity of the solventless moisture-curing adhesive is 120
300,000 mPa · s or less at ℃ is preferable, 1.0
Particularly preferred is 00 to 200,000. The solvent-free moisture-curable adhesive of the present invention may be applied as it is at room temperature, but it is preferably used as a hot-melt adhesive which is melted by heating. In the present invention,
The "hot melt adhesive" includes those which do not show a clear melting point as long as they are liquefied by being heated during use.

A tackifier can be added to the solventless moisture-curing adhesive of the present invention. As a tackifier, terpene resin-based, petroleum resin-based, rosin resin-based, terpene-
Examples thereof include phenol resin type, coumarone-indene resin type, styrene resin type, isoprene resin type and xylene resin type. Examples of the terpene resin-based tackifier include YS-Hara Chemical YS resin series and Hercules piccolite series. Examples of petroleum resin-based tackifiers include Eskoletz 1000 series of Tonen Kagaku, Hilets series of Mitsui Chemicals, and Alcon series of Arakawa Chemical Industry. Examples of the rosin resin-based tackifier include Arakawa Chemical Industries' ester gum series and super ester series. Examples of the terpene-phenol resin tackifier include YS Hara Chemical's YS Polystar series and Mighty Ace series. Examples of the coumarone-indene resin tackifier include the coumarone series of Nippon Steel Chemical. Examples of the styrene resin-based tackifier include Hercules' Picolastic series. Examples of the isoprene resin-based tackifier include Eskoletz 5000 series manufactured by Tonen Kagaku. Examples of the xylene resin-based tackifier include Nikanol series manufactured by Mitsubishi Gas Chemical. Usually, the addition amount thereof is 200% by mass or less, and preferably 150% by mass or less, based on the mass ratio of the isocyanate group-containing prepolymer. Further, a filler, a wax, a plasticizer, an elastomer, an antioxidant, an ultraviolet absorber, a catalyst and the like can be added.

In the method of applying the solventless moisture-curable adhesive of the present invention, the adhesive may be applied directly to the base material, or the adhesive layer may be once formed on the release paper and then transferred to the base material. . Further, although it deviates from the gist of the present invention, it can be used by being dissolved or dispersed in an organic solvent or water.

[0047]

EXAMPLES Next, examples of the present invention will be described in detail, but the present invention is not construed as being limited to these examples. Unless otherwise specified, "%" in Examples and Comparative Examples means "% by mass".

[Allophanate group-containing polyisocyanate
Manufacturing) Synthesis example 1 Volume with stirrer, thermometer, cooler and nitrogen gas inlet pipe
Amount: 1 m of hexamethylene diisocyanate in a reactor
Charge 975 g of (HDI) and 25 g of methanol,
The urethane reaction was carried out at 0 ° C. for 2 hours. The reaction product is F
When analyzed by T-IR, the hydroxyl groups had disappeared.
Next, add 0.2 g of zirconium 2-ethylhexanoate.
And reacted at 90 ° C. for 3 hours. The reaction product is FT-
IR and ¹³When analyzed by C-NMR, a urethane group
Had disappeared. Then, add 0.1 g of phosphoric acid to 50
A termination reaction was performed at 1 ° C for 1 hour. Reaction product after termination reaction
Had an isocyanate content of 42.1%. This reaction
Perform thin film distillation of the product at 130 ° C and 0.04 kPa.
The isocyanate content is 21.1% and the viscosity at 25 ° C is
118 mPa · s, unreacted HDI content is 0.1%,
Polyisocyanate with 20APHA color number and 73% of bifunctional components
Anate P-1 was obtained. P-1 to FT-IR, ¹³C-N
The presence of urethane groups was confirmed by MR analysis.
However, the presence of allophanate groups was confirmed. Also,
Traces of uretdione groups and isocyanurate groups
Was given. The results are shown in Table 1.

Synthetic Examples 2 to 4 Polyisocyanates P-2 to 4 were obtained by using the raw materials and reaction conditions shown in Table 1 in the same procedure as in Synthetic Example 1. The results are shown in Table 1.

Synthesis Example 5 A reactor similar to that of Synthesis Example 1 was charged with 995 g of HDI and NPG.
Was charged in an amount of 5 g, and a urethanization reaction was performed at 90 ° C. for 2 hours. When the reaction product was analyzed by FT-IR, the hydroxyl group had disappeared. Then add tributylphosphine to 1.0
The reaction was carried out at 50 ° C. for 14 hours. When the reaction product was analyzed by FT-IR and ¹³ C-NMR, the presence of urethane group, uretdione group and isocyanurate group could be confirmed, but no allophanate group was confirmed. Further, 0.6 g of phosphoric acid was charged and a termination reaction was carried out at 50 ° C. for 1 hour. The isocyanate content of the product is 42.1%
Met. This reaction product is at 130 ° C and 0.04 kPa
Thin film distillation was carried out at
%, The viscosity at 25 ° C. was 78 mPa · s, the unreacted HDI content was 0.2%, and the polyisocyanate P-5 having a color number of 40 APHA was obtained. The results are shown in Table 1.

[0051]

[Table 1]

In Synthesis Examples 1 to 5 and Table 1, HDI: hexamethylene diisocyanate NPG: neopentyl glycol unreacted HDI content: measured by GPC (calibration curve: HD
I, HDI multimer mixture) Functional group: Judge the peak intensity of each functional group of FT-IR and ¹³ C-NMR * 2 Based on the area% of the peak of the functional component content GPC. Measuring conditions Solvent: THF (tetrahydrofuran) Measuring instrument: Tosoh Corp. HLC-8020 Column: TSKgel G3000H and 4000H

[Production of Solvent-Free Moisture-Curing Adhesive] Example 1 In a reactor having a stirrer, a thermometer, a nitrogen seal tube, and a condenser and having a capacity of 1 L, 464.3 g of Polyol-1 was added,
4.5g of 1,4-BD and 26.3g of NPG were charged,
The mixture was stirred uniformly while heating at 70 ° C. Next, 504.9 g of P-1 and 0.1 g of DOTDL were charged and reacted at 90 ° C. for 3 hours, then 1.0 g of MMP was charged and a solventless moisture-curing adhesive AD-1 made of an isocyanate group-containing prepolymer. Got Isocyanate content of AD-1 is 3.01%, viscosity at 25 ° C is 160,000 mP
a ・ s, the appearance just after production is good and unreacted HDI
Was not confirmed.

Examples 2 to 4 and Comparative Examples 1 to 3 In the same manner as in Example 1, solventless moisture-curing adhesives AD-2 to 7 were obtained with the raw materials and formulations shown in Table 2. The urethanization catalyst is charged when the isocyanate raw material is charged,
The curing accelerating catalyst was charged after the reaction. Since AD-5 gelled, the subsequent evaluation was not performed.

[0055]

[Table 2]

In Examples 1 to 4, Comparative Examples 1 to 3 and Table 2, Polyol-1: 1,2-propylene glycol as an initiator, poly (oxypropylene) diol number average molecular weight = 1,000 Polyol-2: Polyester diol obtained from sebacic acid and 1,6-hexanediol Number average molecular weight = 5,000 Polyol-3: Polyester diol obtained from dodecanedicarboxylic acid and 1,6-hexanediol Number average molecular weight = 3,500 Polyol- 4: Polyester diol obtained from isophthalic acid (iPA), adipic acid (AA), ethylene glycol (EG), neopentyl glycol (NPG) iPA / AA = 1/1, EG / NPG = 1/9 (mol Ratio) number average molecular weight = 2,000 polyol-5: 1,2-propylene glycol Polyether polyol obtained by loading a mixture of propylene oxide / ethylene oxide = 20/80 with Cole as an initiator Number average molecular weight = 2,000 Polyol-6: 1,6-hexanediol and adipic acid Polyesterdiol number average molecular weight obtained = 5,000 NPG: neopentyl glycol 1,4-BD: 1,4-butanediol HDI: hexamethylene diisocyanate Isocyanate content = 50.0% MDI: 4,4'-diphenylmethane diisocyanate Isocyanate content = 33.6% DOTDL: Dioctyltin dilaurate MMP: Methylmorpholine * Viscosity measuring temperature AD-1 is 25 ° C, AD-2 to 7 (excluding AD-5) is 120 ° C. * Appearance during melting Immediately after production: Immediately after production, heat and melt at 120 ° C to evaluate the appearance. After a lapse of time: After manufacturing, fill a 500 ml can with 80% of the capacity,
Purge the voids with nitrogen. After storing at room temperature for 3 months, 1
The appearance is evaluated by heating and melting at 20 ° C. Evaluation: Good → clear, and no particular abnormality is recognized in appearance. Δ → Slight turbidity or the like is observed. × → Peeling is observed and insoluble matter is observed even after heating and melting. * Unreacted HDI content (Comparative Example 3 is unreacted MDI content) According to the area% of the peak of GPC. Measurement conditions Solvent: THF Measuring instrument: Tosoh Corp. HLC-8020 Column: TSKgel G3000H and 4000H

From Table 2, the appearance and storage stability of the solventless moisture-curing adhesive of the present invention immediately after production were good. On the other hand, AD-6 using HDI as it was had an odor at the time of production, and AD-7 using MDI as it was had skinning of the surface over time.

[Adhesion Test] Application Example 1 Using a hot melt applicator, a transparent polypropylene film having a width of 15 cm and a thickness of 20 μm was supplied at a rate of 12 m / min, and AD-1 was 50 μm with a knife coater.
After being applied so as to have a thickness of 10 mm, it was immediately pressure-bonded to the cover material for 10 seconds with a pressure roller. In addition, AD-1 was applied without heating. Then, it was aged for 72 hours at 25 ° C. × 50% RH, and the adhesive strength (180 ° peel strength) was measured.
Further, the cured adhesive sample was exposed outdoors for 3 months, and the adhesive strength (180 ° peel strength) was measured. The results are shown in Table 3. In addition, curing and exposure were performed with the width being wide, and the sheet was cut into a width of 25 mm immediately before the peel strength was measured and then set in a tester. Peel strength measurement conditions Tensile speed: 100 mm / min Measurement atmosphere: 50% RH, 25 ° C

Application Examples 2 to 4 and Comparative Examples 1 to 2 AD-2 to 7 (excluding AD-5) were used instead of AD-1, and the adhesive was heated and melted at 120 ° C. for application. Was applied, cured and evaluated in the same manner as in Application Example 1. The results are shown in Table 3.

[0060]

[Table 3]

In Table 3 Appearance evaluation of adhesive samples ◯: No coloring (yellowing) is confirmed. Δ: Some coloring (yellowing) is confirmed. X: Large coloring (yellowing).

From Table 3, the solventless moisture-curing adhesive of the present invention showed good adhesiveness and weather resistance. Also, the environment during the bonding work was good. However, AD-6 using the HDI monomer as such had a considerable odor, and AD-7 using the MDI monomer showed a considerable yellowing after exposure.

[0063]

As described above, the solventless moisture-curing adhesive of the present invention has good weather resistance and little odor (especially when heated). INDUSTRIAL APPLICABILITY The solventless moisture-curing adhesive of the present invention can be widely applied to woodworking including profile wrapping, film lamination, structural use, fabric adhesion, bookbinding, corrugated board assembly, and the like.

Continued front page    F-term (reference) 4J034 BA02 BA03 CA02 CA03 CA04                       CA15 CC03 CC07 CC08 CC09                       CD01 DF01 DF02 DF12 DG03                       DG04 DG05 DH01 HD05 JA01                       KC16 KC17 KD02 KD12 QA01                       QA05 RA08                 4J040 EF071 EF111 EF121 EF131                       EF161 EF181 EF201 EF281                       EF321 JB04 LA05 LA07                       PA34

Claims (3)

[Claims] 1. A solventless moisture-curing adhesive consisting of (A) an organic polyisocyanate and (B) an isocyanate group-containing prepolymer obtained by reacting an active hydrogen group-containing compound. The isocyanates are (A1) hexamethylene diisocyanate and (A
2) Alkyl monool having 1 to 10 carbon atoms is added to (A
3) A solventless moisture-curing adhesive, which is a polyisocyanate obtained by allophanating in the presence of a carboxylic acid zirconium salt. 2. The solventless moisture-curing adhesive according to claim 1, wherein the content of unreacted hexamethylene diisocyanate is 0.5% by mass or less. 3. The solvent-free moisture-curable adhesive according to claim 1, wherein the isocyanate content is 1 to 5% by mass.