JP3361244B2 - Aqueous urethane resin adhesive composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous urethane resin adhesive composition, and more particularly to an adhesive for dry laminating plastic films and the like useful for forming food packaging bags and the like.

[0002]

2. Description of the Related Art Conventionally, a dimethylolalkanoic acid compound has been used as a part of a raw material of a urethane resin to prepare a urethane resin having an ionic functional group in the molecule, and an aqueous adhesive composition using the resin has been known. (JP-A-8-2257)
No. 80). Further, a method for obtaining an aqueous urethane resin dispersion by introducing an ionic functional group into the urethane resin by using trimellitic anhydride and a trimethylolpropane adduct half ester as a part of the raw material of the urethane resin (special characteristics Kaihei 7
No. 196748) is also known.

Further, Japanese Patent Application Laid-Open No. 5-97962 discloses that
Although a method for stabilizing the dispersion of the urethane resin by leaving a carboxyl group in the urethane resin has been shown, these methods have advantages and disadvantages.For example, these urethane resin aqueous dispersions are gravure rolls or the like. A plate clogging phenomenon is a major problem in coating suitability for gravure rolls when applied to a film.

Conventionally, in the urethane resin aqueous dispersion, almost all of the ionic functional groups contained in the urethane resin are neutralized. In particular, a volatile amine compound is often used as the neutralizing agent used.
The reason is that when the neutralizing agent is dried in the urethane resin aqueous dispersion,
It is expected to be released from the resin by the heat and the ionic functional group is regenerated to exhibit adhesiveness and crosslinkability. However, when the ionic functional group is a carboxyl group, sulfonic acid, etc., if a volatile amine-based one is used as the neutralizing agent, the desorbed amine may contaminate the plastic film when desorbed by drying. It becomes unsuitable for food packaging bags.

Further, conventionally, when the ionic functional group of the urethane resin aqueous dispersion is neutralized with an alkali metal, the alkali metal salt is not detached from the resin by heat during drying and remains as it is with the resin. It had a drawback that the water resistance of the agent was poor. Further, conventionally, it is very difficult to select a cross-linking agent to be used as a main material of the adhesive because the adhesive for a plastic film cannot be heat-treated at a high temperature for a long time. Therefore, it is preferable to use a carbodiimide-based curing agent that crosslinks at low temperature, but conventional long-chain carbodiimide crosslinking agents easily react with ionic functional groups, and resin aqueous dispersions containing free acid-type ionic functional groups When it is used in combination with the body, the solution stability of this aqueous dispersion is significantly deteriorated. Therefore, in the case of an adhesive composition comprising a resin water dispersion and a cross-linking agent, there arises a problem that the coating suitability deteriorates with time under the use conditions (use process).

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned various problems of the prior art and to provide an aqueous urethane resin adhesive composition having good adhesiveness to a plastic film and excellent solution stability. Is to provide.

[0007]

The above object can be achieved by the present invention described below. That is, the present invention has a molecular weight of 500 to
A urethane resin obtained from a 5,000-terminal OH group-containing polyol, a compound having an ionic functional group, a chain extender compound, and an isocyanate compound, in which 5 to 50% of the ionic functional group is unreacted. Urethane resin water dispersion that is neutralization, and the amount that has one or more carbodiimide groups
At least four child chains are linked in a branched form
A water-based urethane resin adhesive composition comprising a cross-linking agent containing a branched polyfunctional carbodiimide compound .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. The water-dispersible urethane resin constituting the adhesive composition of the present invention has a terminal OH group-containing polyol component (molecular weight of 500 to 5,000, preferably 1,000).
~ 3,000 polyols) and the polyol component of 0.
An ionic functional group-containing compound in an amount of 7 to 1.5 mol,
In the terminal NCO prepolymer obtained from the diisocyanate compound, the terminal NCO group of the prepolymer is 6
0 to 90 mol% is chain-extended with diamine or a derivative thereof to be polymerized, and residual terminal NCO groups are masked with a reaction terminator. The molecular weight of the obtained polymer is preferably 10,000 to 30,000 (theoretical value).

The urethane resin used in the present invention has a molecular weight of 10,000 to 30,000 (theoretical value), and when the molecular weight is larger than the above numerical value, the resulting water dispersion adhesive composition is applied to a film or the like. The coating suitability at the time of coating deteriorates with time, coating unevenness occurs, and adhesive strength becomes uneven. Further, the crosslinking rate with the crosslinking agent used in combination becomes slow, which is not preferable. The urethane resin as described above is excellent in stability in an aqueous medium, and when it is used as an adhesive composition, it is excellent in stability on a coating machine, and is unlikely to cause a problem of plate clogging during gravure roll work. While maintaining the stability of the aqueous dispersion composition system with the carbodiimide-based curing agent, it has excellent curing characteristics after application of the adhesive (after application and drying). Then, the aqueous dispersion resin component in which 50 to 95% of the ionic functional groups contained in the polymer are neutralized with an alkali metal and the remaining 5 to 50% exist in a free state is used as an adhesive resin component. .

Since the urethane resin used in the present invention has a free functional group, the free functional group serves to improve the adhesiveness to the plastic film, and at the same time, particularly, a carbodiimide type crosslinking agent or an epoxy resin type is used. When used in combination with a cross-linking agent, because of its excellent cross-linking effect, even if the ionic functional group of the urethane resin used in the present invention is neutralized with an alkali metal, it causes a particularly poor water resistance of the adhesive. Don't The reason why the ionic functional group neutralizing agent contained in the urethane resin is an alkali metal is that the alkali metal is not volatile, and therefore even if an adhesive made of this urethane resin is used for bonding a plastic film or the like. The alkali metal does not contaminate this film.

Polyol components which can be used as a raw material for the urethane resin in the present invention are polyester polyols and polyether polyols, and examples of the polybasic acid constituting the polyester polyols include adipic acid, azelaic acid, sebacic acid and sperin. Aliphatic acids such as acids, phthalic acid, phthalic anhydride, isophthalic acid, dimethylisophthalic acid, terephthalic acid, aromatic acids such as dimethylterephthalic acid, trimellitic acid, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, fumaric acid Examples include polybasic acid compounds such as acids.

Examples of the diols constituting the polyester polyol include ethylene glycol, propylene glycol, 1,3-butylene glycol,
1,4-butylene glycol, dimethyl propanediol, 3-methyl-1,5-pentanediol, 1,6-
Examples thereof include diols and glycols such as hexanediol, octanediol, neopentyl glycol, cyclohexanedimethanol, diethylene glycol and dipropylene glycol.

Other polyester polyols include lactone polyester polyols and the like, and the lactone polyester polyols are polyγ-butyrolactone and polyε-obtained by using the above glycols as an initiator.
Ring-opening polymerized polyester polyol such as caprolactone,
And polycarbonate ester diols such as poly (hexamethylene carbonate) diol. Examples of the polyether polyol include polytetramethylene glycol, the above-mentioned glycol, polypropylene oxide obtained by polymerizing alkylene oxide using diol as an initiator, polyethylene glycol, and polyalkylene glycol such as copolymerized polyol.

Examples of the diisocyanate compound used in the constitution of the urethane resin used in the present invention include aromatic diisocyanate compounds such as tolylene diisocyanate and diphenylmethane diisocyanate, aliphatic diisocyanate compounds such as lysine diisocyanate and hexamethylene diisocyanate, and isophorone. Examples of the non-yellowing diisocyanate compound such as diisocyanate, xylylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate, and dimer acid diisocyanate.

Examples of the chain extender used in the construction of the urethane resin used in the present invention include ethylene glycol, propylene glycol, butylene glycol, dimethylpropanediol, hexanediol, methylpentanediol, octanediol, neopentylglycol, Cyclohexanedimethanol, glycols such as diethylene glycol and dipropylene glycol, glycerin, triols such as trimethylolpropane, ethylenediamine, propylenediamine, hexamethylenediamine, hydrazine and hydrazine derivative compounds, piperazine and piperazine compounds, diaminodicyclohexylmethane, diphenylmethanediamine , Amine compounds such as xylenediamine and isophoronediamine.

Examples of the compound having an ionic functional group used in the construction of the urethane resin used in the present invention include dimethylolalkanoic acid such as dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolvaleric acid. The compounds described in JP-A-43-9076 can be used. Further, a half-ester compound obtained from a triol and a dicarboxylic acid compound can also be used as a compound having an ionic functional group. Furthermore, compounds such as amino acids, sodium aminosulfonate, sodium diaminobenzenesulfonate and the like can be used.

The compound having an ionic functional group is, for example, an acid value of 50 to 200 and a hydroxyl value of 100 to 50.
0 half-ester compound, for example, a trifunctional polyol obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to a trifunctional alcohol compound such as glycerin or trimethylolpropane, and an aliphatic dicarboxylic acid such as maleic anhydride. A half-ester compound containing a carboxyl group and a hydroxyl group, which is obtained from an aromatic dicarboxylic acid anhydride such as an acid, phthalic anhydride, or trimellitic acid, or a trimellitic acid compound can be used.

The urethane resin aqueous dispersion used in the present invention can be obtained from the above raw materials by a conventionally known method, and a preferable production method is as described in the below-mentioned Examples, for example, the above-mentioned molecular weights. Terminal N in an organic solvent from 500 to 5,000 terminal OH group-containing polyol, a compound having an ionic functional group, and an isocyanate compound.
It is obtained by preparing a CO prepolymer, polymerizing the obtained prepolymer with a chain extender, and neutralizing ionic functional groups in the produced polymer.

The specific carbodiimide compound used as a cross-linking agent in obtaining the adhesive composition of the present invention is prepared by reacting a compound containing at least one carbodiimide group with a compound containing a hydroxyl group, an amino group or an amide group. The resulting multi-branched carbodiimide compound. Details of the manufacturing method, the amount used, and the like are as described in Examples. The ratio of the urethane resin and the crosslinking agent used is
This is the same as in the prior art and varies depending on the object to which the adhesive is used, but generally, the crosslinking agent is in the range of 0.5 to 15 parts by weight per 100 parts by weight of the urethane resin.

[0020]

EXAMPLES Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. It should be noted that the term "central part" is based on weight. Reference Example 1 1a. Prepolymer compounding example Reaction component PPG-2000 (hydroxyl value 56, 1.0 mol) 1,000 parts DMPA (0.8 mol) 53.5 parts TDI (2.7 mol) 234.5 parts Acetone (diluting solvent) 143.1 copies 1431.1 copies in total

Polypropylene glycol having an average molecular weight of 2,000 (PPG-2000), dimethylolpropionic acid (DMPA), tolylene diisocyanate (TD)
I) and acetone (diluting solvent) were mixed in a 2,000 ml urethane resin reaction kettle in the proportions (parts) shown in the above formulation example, and reacted for about 4 hours while maintaining the temperature at 60 to 70 ° C. A urethane prepolymer solution having an NCO content of 2.64% and a carboxyl group content of 0.28 meq was obtained.

1b. Neutralization reaction formulation example DBA (polymerization regulator, 0.3 mol) 24.3 parts LiOH.H ₂ O (neutralizing agent, 0.85 mol) 10.0 parts Ion-exchanged water (neutralizing agent dilution water) 893 .7 part 1c. Chain extension reaction formulation example 60% Hydrated hydrazine (chain extender, 0.21 mol) 5.4 parts IPDA (chain extender, 0.49 mol) 26.2 parts Ion-exchanged water (chain extender dilution water) 446 .9 copies

Above 1a. In the urethane reaction kettle illustrated in
1b. Dibutylamine (DB
A) and lithium hydroxide (LiOH.H ₂ O) were mixed and dissolved in an aqueous solution, and the mixture was stirred at room temperature to neutralize about 85% of the carboxyl groups contained in the urethane prepolymer (15 Leave% as free)
At the same time, DBA was used to mask about 30% by mole of the isocyanate groups contained in the urethane prepolymer.

Then, while continuing to stir, 1
c. The chain extender solution in which 60% hydrous hydrazine and IPDA (isophoronediamine) are dissolved is added to the chain extender-containing diluted water exemplified in, and the mixture is vigorously mixed, and the temperature is adjusted to 40-
While maintaining the temperature at 50 ° C., stirring was continued for 60 minutes to complete the reaction. Then, the acetone was decompressed and removed outside the reaction kettle system. The resulting urethane resin water dispersion has a solid content of about 40.
%, A viscosity of about 110 cps / 25 ° C., a pH of about 6.9, and a theoretical molecular weight of about 9,941 (hereinafter, this urethane resin aqueous dispersion is simply referred to as PUD-1).

In the same manner as in Reference Example 1, aqueous dispersions of urethane resin shown in Table 1 below were obtained. These urethane resins (PUD2-4) are used as comparative examples.

[Table 1]

Reference Example 2 (Specific carbodiimide cross-linking compound) As a specific carbodiimide cross-linking compound, there is disclosed in Japanese Patent Laid-Open Publication No.
The hyperbranched polyfunctional polycarbodiimide compound described in JP-A-130624 can be used.
That is, it is a multi-branched polyfunctional polycarbodiimide compound (A) in which at least four or more molecular chains having at least one carbodiimide group in the molecule are bonded in a branched form. The compound (A) is an isocyanate compound (a) having one or more carbodiimide groups and one or two or more isocyanate groups, and a polyol having four or more hydroxyl groups, amino groups and / or imino groups in the molecule. , A polyamine and / or an amino alcohol (b) and, if necessary, a monoalcohol or monoamine having one hydroxyl group, an amino group and / or an imino group in the molecule, and an oxime compound (c). It is a reaction product.

More specifically, 30% toluene of polyhexamethylene carbodiimide (average number of carbodiimide groups in one molecule: 2.8) obtained by condensing 4 molecules of hexamethylene diisocyanate and having isocyanate groups at both ends. 631.4 parts of the solution was charged into a condensation reaction vessel, 1.3 parts of a 5% solution of a catalyst (dibutyltin dilaurate) in methyl ethyl ketone was added, and the mixture was heated to 60 ° C. to obtain polyethylene glycol monomethyl ether (molecular weight: about 1,000). 60% of 508.5 toluene solution 468.5 parts
It was made to react by dripping over minutes. Then, the temperature was raised little by little, and the reaction was continued at 100 ° C. for 3 hours. Next, 37.6 parts of a 50% toluene solution of decaglycerin monolaurate (average number of hydroxyl groups in one molecule: about 11) was added to 10 parts.
The mixture was added dropwise at 0 ° C over 60 minutes, and the reaction was continued for 1 hour.

The reaction was judged by infrared absorption spectroscopy by confirming the reduction of isocyanate groups and the formation of urethane groups. Then, the toluene is allowed to flow out at 115 ° C. for 2 hours, further depressurized and further distilled. Water 1,7 at 50 ° C
70 parts was added to obtain an aqueous solution (solid content: 20%) of a branched carbodiimide compound. Hereinafter, this is referred to as cross-linking agent-1.

In the method for producing the crosslinking agent-1, water 1,7
Instead of adding 70 parts, a water-soluble organic solvent (for example, propylene glycol monomethyl ether or the like) can be used. A general (commercially available) carbodiimide-based cross-linking agent is mainly a bifunctional one (for example, JP-A-7-316248 and JP-A-7-330).
849, JP-A-8-208788, and JP-A-8-208789).

Comparative Example 700 parts of hexamethylene diisocyanate and 14 parts of carbodiimidization catalyst (3-methyl-1-phenyl-2-phosphorene-1-oxide) were reacted at a temperature of 180 ° C. for 6 hours to give 93. 4 parts and 2-dimethylaminoethanol 17.8
After reacting 24 parts at a temperature of 80 ° C. for 24 hours, 37.2 parts of methyl p-toluenesulfonate was added, and the mixture was stirred for 1 hour for quaternization. Water was added to this to adjust the solid content to 20%. The obtained carbodiimide cross-linking agent was used as a comparative example (hereinafter referred to as cross-linking agent-2 (comparative example)).

Example 1: Adhesive composition PUD-1 100.0 parts Crosslinking agent-1 10.0 parts This compounded composition was stirred and mixed at room temperature to obtain an adhesive composition of the present invention (hereinafter referred to as NSB. -1). In order to compare the solution stability of the adhesive composition, an adhesive composition similar to NSB-1 was prepared using PUD-2 to 4 as shown in Table 2 below to prepare an adhesive composition of a comparative example. did.

[0032]

[Table 2] In the above table, when the cross-linking agent-1 was blended, the cross-linking agent-2 was not blended. On the contrary, when the crosslinking agent-2 was blended, the crosslinking agent-1 was not blended.

The results of measuring the viscosity based on the composition table shown in Table 2 are shown in Table 3 below.

[Table 3] However, the solution viscosity in the above table was measured at a liquid temperature of 25 to 26 ° C. using a B type rotational viscometer. In Table 3 above, the left side shows the results when the crosslinking agent-1 was used, and the right side shows the results when the crosslinking agent-2 (comparative example) was used (viscosity: mPas / 2).
5 ° C).

Adhesive Strength Test Immediately after compounding NSB-1 and NSB-1A-C, each OPP film of about 25 μm (wetting index about 38 dynes)
The adhesive solid content at a rate of about 2.2 parts / m ² ,
Immediately, about 60 μm CPP film (wetting index about 38
˜40 dynes). Adhesive strength (width 15 mm, T-shaped peeling, pulling speed 300 mm / min) after aging this laminated film at a temperature of 35 to 40 ° C. for 48 hours
The measurement results are shown in Table 4 below.

[0035]

[Table 4] In Table 4 above, the left side shows the results when the cross-linking agent-1 was used, and the right side shows the results when the cross-linking agent-2 (comparative example) was used.

Boiling Test Adhesive compositions for boiling tests were prepared as shown in Table 5 below.

[Table 5]

Epoxy compound: Denacol EX421
(Nagase Sangyo Co., Ltd.) was used at the same time as a crosslinking aid.
Immediately after blending NSB-2 and NSB-2A-C, each is applied to an ONy (wetting index of about 40 dynes) film of about 20 μm at a rate of about 2.7 parts / m ² in terms of adhesive solid content,
Immediately, about 60 μm LLDPE (wetting index about 38-4
0 dynes) and laminated. The laminated film was aged at a temperature of 35 to 40 ° C. for 48 hours, filled with tap water, and then made into a bag to give a test sample. This sample was boiled for 30 minutes. The adhesive strength was measured with a width of 15 mm, T-shaped peeling and a pulling speed of 300 mm / min.

[0038]

[Table 6] In Table 6 above, the numerical value on the left side indicates the adhesive strength before the boiling test, the numerical value on the right side indicates the adhesive strength after the boiling test, and “peeling” means a sample that is in a peeled state after the boiling test.

Plate clogging test Adhesives: NSB-1 and NSB-1A to C, to which 40 parts of pure water was added, were used, and a thickness of 20 μm was obtained using a gravure roll of 165 lines / inch and a depth of 25 μm. Of OPP film. After 3 minutes from the start of coating at a coating speed of 50 m / min, the coating operation was stopped for 3 minutes, and then the coating operation was further started. While the coating operation is stopped, the adhesive is in a dry to semi-dry state on the air side surface of the gravure roll. And when the coating work starts
The adhesive film in the semi-dried portion returned to the adhesive liquid vat (by repeating this) and the time for re-dissolution was compared.

[0040]

[Table 7]

[0041]

According to the present invention, the following effects can be obtained. (1) When a conventional urethane resin water dispersion is applied as an adhesive for dry lamination, especially by a gravure roll, a problem of plate clogging occurs. That is, the printability is poor. This seems to be a phenomenon peculiar to the resin water dispersion liquid, and the adhesive left without being transferred from the gravure roll plate to the adherend surface returns to the adhesive bat again and the adhesive liquid in the bat It must dissolve and become homogeneous. This phenomenon is called redissolvability. In the case of the urethane resin aqueous dispersion, this re-solubility is particularly bad, and thus the problem of plate clogging of the gravure roll easily occurs.

(2) In the present invention, the molecular weight is 1,000 to
When a urethane resin aqueous dispersion (self-emulsifying property) is obtained based on 3,000 difunctional polyols, the resin having a molecular weight of about 10,000 to 30,000 is used as the adhesive agent. It was found that the re-dissolvability in the vat is very good (usually, in the case of the urethane resin aqueous dispersion, the molecular weight is 50,000 or more. Polyol molecular weight:
1,000-3,000: based on 2,000: N
CO / OH ratio, 2.0 to 1.2, chain extension rate 90% or more). In the present invention, the chain extension rate is 70 to 90% in order to control the molecular weight.

(3) If the neutralization rate of the ionic functional groups in the urethane resin is low, the dispersion stability of the resin aqueous solution is impaired and the stability on the coating machine is deteriorated. However, when the molecular weight of the resin is within the range shown in the item (2), the gravure roll on-machine stability is very good even when the neutralization ratio of the ionic functional group is 85%, and further the printability (plate clogging is prevented). Problem) is also good and continuous coating work is possible for a long time.

(4) Conventionally, in order to facilitate regeneration of the neutralized ionic functional group, a volatile compound (for example, an amine compound) is generally used as the neutralizing agent. However, since amine compounds contaminate adherends such as air and film, the resin aqueous dispersion neutralized with amine compounds cannot be used as an adhesive for dry lamination of plastic films used for food packaging bags and the like. .

(5) Since the urethane resin used in the present invention has an unneutralized ionic functional group (carboxyl group) remaining, it has excellent adhesiveness to a plastic film. Then, the reactivity of the unneutralized carboxyl group with the cross-linking agent (epoxy resin cross-linking agent and / or carbodiimide-based cross-linking agent) is good, and the water resistance of the adhesive can be efficiently improved. However, ordinary linear carbodiimide cross-linking agents have too fast a reactivity with the carboxyl group, so that the pot life of the adhesives using these cross-linking agents becomes very short.

On the other hand, in the case of the adhesive composition of the present invention, a multi-branched carbodiimide crosslinking agent (specific carbodiimide crosslinking agent) obtained by adding a specific urethane resin to a stem compound having water dispersion stability It has excellent stability and an excellent long pot life. (6) The aqueous resin dispersion used in the present invention is a resin neutralized with a non-volatile alkali metal, and an adhesive composition comprising the resin and a hyperbranched carbodiimide crosslinking agent (and an epoxy resin). By using the above, it is possible to obtain a dry laminating adhesive having excellent water resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michie Nakamura 1-7-6 Nihonbashi Bakurocho, Chuo-ku, Tokyo Inside Dainichi Seika Kogyo Co., Ltd. (72) Inventor Yoshinori Imano 1-7-Nihonbashi Bakurocho, Chuo-ku, Tokyo 6 Dainichi Seika Kogyo Co., Ltd. (72) Inventor Toru Oura 1-7-7 Nihonbashi Bakurocho, Chuo-ku, Tokyo 6 Dainichi Seika Kogyo Co., Ltd. (72) Inventor Hiroyuki Shimanaka 1-7-Nihonbashi Bakuro-cho, Chuo-ku, Tokyo 6 within Dainichiseika Kogyo Co., Ltd. (56) Reference JP-A-8-27242 (JP, A) JP-A-8-225780 (JP, A) JP-A-8-269429 (JP, A) JP-A-6 -32883 (JP, A) JP-A-8-246355 (JP, A) JP-A-7-216340 (JP, A) JP-A-2-127491 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) C09J 175/04

Claims (3)

(57) [Claims] 1. A polyol having a terminal OH group having a molecular weight of 500 to 5,000, and a compound having an ionic functional group,
A urethane resin obtained from a chain extender compound and an isocyanate compound, wherein the ionic functional group is 5 to 5
0% un-neutralized urethane resin water dispersion, 1 or more
At least 4 or more molecular chains having a carbodiimide group of
Hyperbranched polyfunctional carbodies linked in an upper branched fashion
An aqueous urethane resin adhesive composition comprising a cross-linking agent containing an imide compound . 2. The adhesive composition according to claim 1, wherein the ionic functional group of the urethane resin is neutralized with an alkali metal. 3. When the average molecular weight of the OH group-containing polyol is 2,000, the molecular weight of the urethane resin is 10,
The adhesive composition according to claim 1, which is 000 to 30,000.