Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-03-01
2001-10-30
Gallagher, John J. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C525S457000, C560S330000
Reexamination Certificate
active
06309507
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a hydrophilic polar group-containing polyisocyanate curing agent for a laminate adhesive, to a laminate adhesive comprising the same, and to use of the laminate adhesive in film lamination.
2. Related Prior Art
Recently, as a packaging method, a complex flexible packaging has been remarkably developed for reasons such as strength of package, protective properties for commercial product, workability during packaging, propaganda effect of package, reduction of packaging cost caused by the supply of a large amount of film at a low cost, and the like.
As an adhesive used in film lamination in such complex flexible packaging, the main product has been a two-pack curing type polyurethane adhesive composed of a resin having an active hydrogen-containing group such as a hydroxyl group or the like (main ingredient) and a polyisocyanate (curing agent) because it is excellent in bond performance, durability and heat resistance and it can be applied to various films in a broad range.
For example, JP-A-5-112,766 discloses an adhesive comprising a polyurethane resin and a polyisocyanate curing agent wherein the polyurethane resin has introduced thereinto a hydrophilic polar group. Moreover, JP-A-7-48,429 describes a polyisocyanate curing agent in which a hydrophilic polar group has been introduced into the polyisocyanate.
However, with the polyisocyanate curing agent described in JP-A-5-112,766, the use of other resins than the polyurethane resin as the main ingredient results in an insufficient adhesiveness to a metal foil, a metallized film or a polyolefin film. Furthermore, in JP-A-7-48,429, an aqueous adhesive is mentioned; however, the aqueous adhesive requires blowing water away and hence much energy becomes necessary therefor.
SUMMARY OF THE INVENTION
An object of this invention is to provide a polyisocyanate curing agent for a laminate adhesive which is excellent in heat-resistance, durability and adhesiveness to a metallic film and a polyolefin film.
A further object of this invention is to provide a laminate adhesive excellent in heat-resistance, durability and adhesiveness to a metallic film and a polyolefin film which adhesive comprises the above-mentioned curing agent.
A still further object of this invention is to provide use of the above adhesive in film lamination.
Other objects and advantages of this invention will become apparent from the following description.
According to this invention, there are provided the following:
(1) a polyisocyanate curing agent for a laminate adhesive, which comprises a hydrophilic polar group-containing polyisocyanate,
(2) a laminate adhesive, which comprises the polyisocyanate curing agent mentioned in (1) above and an active hydrogen-containing compound, and
(3) use of an adhesive comprising the polyisocyanate curing agent mentioned in (1) above and an active hydrogen-containing compound in film lamination.
DETAILED DESCRIPTION OF THE INVENTION
The polyisocyanate curing agent for a laminate adhesive of this invention comprises a hydrophilic polar group-containing polyisocyanate.
The hydrophilic polar group-containing polyisocyanate can be easily obtained by reacting an organic polyisocyanate with a hydrophilic polar group-containing compound having at least one active hydrogen-containing group.
The organic polyisocyanate includes known organic polyisocyanates and their modified products.
Specific examples thereof include, for example, aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, xylylene-1,2-diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenyl ether diisocyanate, 2-nitro-diphenyl-4,4′-diisocyanate, 2,2′-diphenylpropane-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocya-nate, 4,4′-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-di-methoxydiphenyl-4,4′-diisocyanate, tetramethylxylylene diisocyanate and the like; aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate and the like; alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate and the like; their adducts; biuret bond-containing polyisocyanates derived from the above diisocyanates, carbodiimide bond-containing polyisocyanates derived from the above diisocyanates, uretonimine bond-containing polyisocyanates derived from the above diisocyanates, uretdione bond-containing polyisocyanates derived from the above diisocyanates and isocyanurate bond-containing polyisocyanates derived from the above diisocyanates; and polymers thereof. The above-mentioned diisocyanates and polyisocyanates derived from the diisocyanates can be used alone or in admixture of two or more.
Among them, isocyanurate bond-containing polyisocyanates derived from hexamethylene diisocyanate and polyisocyanate having isocyanurate bond and uretdione bond derived from hexamethylene diisocyanate are preferable because they are excellent in durability, heat-resistance and the like.
As the hydrophilic polar group in the hydrophilic polar group-containing compound having an active hydrogen-containing group, there are mentioned nonionic polar groups, anionic polar groups, cationic polar groups and amphoteric polar groups. In this invention, they may be used alone or different kinds of hydrophilic polar groups may be adopted in combination. Taking into consideration the stability of the obtained polyisocyanate curing agent for a laminate adhesive, nonionic polar groups are preferred as the hydrophilic polar group of the polyisocyanate curing agent of this invention.
As the nonionic polar group-containing compound having an active hydrogen-containing group, there are mentioned polyoxyalkylene ether mono-ols, polyoxyalkylene ether polyols, polyoxyalkylene fatty acid ester mono-ols and the like in which the proportion of ethylene oxide unit is at least 50 mole % and the number of units repeated is preferably 3 to 90, more preferably 5 to 50. In this invention, the polyoxyalkylene ether mono-ols and the polyoxyalkylene ether polyols are preferable and the polyoxyalkylene ether mono-ols are more preferable.
As an initiator in the production of the above polyoxyalkylene ether mono-ols, there are mentioned methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, cyclohexanol, phenol and the like. As an initiator in the production of the above polyoxyalkylene ether polyols, there are mentioned ethylene glycol, propylene glycol, aniline, trimethylolpropane, glycerol and the like. Among them, compounds having not more than 5 carbon atoms such as methanol, ethanol, ethylene glycol, propylene glycol and the like are preferable because the adhesiveness to a metal becomes good, and mono-ols having not more than 5 carbon atoms such as methanol, ethanol and the like are more preferable.
Moreover, as the fatty acid used in the production of the above polyoxyalkylene fatty acid ester mono-ol, there are mentioned acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric acid, i-valeric acid, caproic acid, glycolic acid, lactic acid, methoxyacetic acid and the like. Among them, fatty acids having not more than 5 carbon atoms such as acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric acid, i-valeric acid and the like are preferred because the adhesiveness to a metal becomes good.
Suitable examples of the anionic polar group-containing compound having an active hydrogen-containing group include those which are each composed of an organic acid having at least one active hydrogen-containing group and a neutralizing agent. As the above organic acid, there are mentioned compounds having carboxylic group, sulfonic aci
Konishi Shin
Morikawa Yukihiro
Sasahara Toshiaki
Browdy and Neimark
Gallagher John J.
Nippon Polyurethane Industry Co., Ltd.
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