Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2000-07-27
2001-09-11
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S059000
Reexamination Certificate
active
06288201
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a laminate adhesive and, more particularly, to a laminate adhesive which is useful for the manufacture of packaging materials for use in a variety of industrial fields, including packaging materials for food products, beverages, medical products and quasi-drags or packaging materials for electronic components such as hard disks.
2. Description of the Prior Art
Composite film produced by lamination of e.g. plastic film, metal foil of e.g. aluminum, metallized film, and silica evaporated film by use of an adhesive have been widely used as packaging material for use in a variety of industrial fields including packaging materials for food products, beverages, medical products and quasi-drags or packaging materials for electronic components such as hard disks up to the present date.
A two component ester urethane adhesive, using polyisocyanate in combination with polyester polyol or polyester polyurethane polyol, is used most as the laminate adhesive for the manufacture of these packaging materials, because of its excellent adhesion properties.
It is known, on the other hand, that polyester polyol produces by-products of cyclic ester compounds in the manufacture of it, and it has been hitherto believed to be hard to avoid the production of such by-products.
In recent years, there have advanced the studies on the substance to be eluted from packaging material into a content, which suggests the possibility that some low molecular weight compounds may be eluted from the adhesive into the content and the low molecular weight compounds thus eluted may attribute the cause, in part, to spoil the inherent properties of the content, such as the odor and taste of food products and beverages, or the inherent performances of the electronic components, though the cause and effect relationship has not yet been clarified.
It is the object of the present invention to provide a laminate adhesive that can suppress the elusion of a low molecular weight compounds of composite film into the content, so as to prevent the inherent properties or performances of the content from being spoiled by the low molecular weight compounds.
SUMMARY OF THE INVENTION
The present invention is directed to a novel laminate adhesive comprising a polyisocyanate component and a polyol component, wherein the polyol component includes polyester polyol and/or polyester polyurethane polyol which is produced by reaction of polyester polyol and polyisocyanate, and wherein concentration of cyclic compounds in extracted water which are extracted from a composite film bonded by the laminate adhesive by water of 0.5 mL/cm
2
per unit area of the composite film is 0.5 ppb or less in terms of dibutyl phthalate concentration measured by a gas chromatograph-flame ionization detector.
The cyclic compounds include cyclic ester compounds and/or cyclic urethane compounds.
According to the laminate adhesive of the present invention, it is preferable that the polyester polyol comprises dimer acid. The polyester polyol may comprise phtalic acid and glycol having 6-7 carbons in its principal chain.
According to the laminate adhesive of the present invention, it is preferable that unreacted glycols in the polyester polyol is 0.1 weight % or less. When the polyester polyurethane polyol is contained in the polyol component, it is preferable that the polyisocyanate used for obtaining the polyester polyurethane polyol comprises dicyclohexylmethane-4,4′-diisocyanate and/or diphenylmethane-4,4′-diisocyanate.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The laminate adhesive of the present invention comprises a polyisocyanate component and a polyol component.
Polyisocyanates commonly used in the manufacture of polyurethane may be used as the polyisocyanate components of the invention. Examples of the polyisocyanate components include polyisocyanate monomers and derivatives thereof.
Examples of the polyisocyanate monomers include aliphatic diisocyanate such as hexamethylene diisocyanate, alicyclic diisocyanate such as 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3- or 1-4-bis(isocyanatomethyl) cyclohexane or mixtures thereof, aralkyl diisocyanate such as 1,3- or 1-4-xylylene diisocyanate or mixtures thereof, 1,3- or 1-4-bis(1-isocyanato-1-methylethyl)benzene or mixtures thereof, and aromatic diisocyanate such as 2,4- or 2,6-tolylenediisocyanate or mixtures thereof, diphenylmethane-4,4′-disocyanate.
Examples of the derivatives of the polyisocyanate monomers include dimers or trimers of polyisocyanate monomers, biurets, allophanates and oxadiazinetriones obtained by reaction of the polyisocyanate monomers with water, polyhydric alcohol, carbon dioxide gas and so on. Two or more of these monomers and derivatives thereof may be used in combination.
Polyols commonly used in the manufacture of polyurethane may be used as the polyol components of the invention. Preferable examples of the polyol components of the invention include polyester polyol and polyester polyurethane polyol.
The polyester polyol can be obtained by a known esterification reaction, i.e., by a condensation reaction between polybasic acid and polyhydric alcohol or by an ester interexchange reaction between alkyl ester of polybasic acid and polyhydric alcohol.
Preferable examples of the polybasic acids and alkyl esters thereof include dimer acid, phthalic acid, such as orthophthalic acid, isophthalic acid and terephthalic acid, or dialkyl esters thereof or mixtures thereof. The dimer acid comprises, in general, a dimer of unsaturated aliphatic acid having 18 carbons as its major component which is available as industrial material and additionally includes a monomer acid and a trimer acid.
Preferably, the polyhydric alcohols include glycol, such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexandiol, 1,7-heptanediol, 1,9-nonanediol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, or 2-methyl-1,8-octanediol, triol such as glycerine or trimethylolpropane, dimethylol alkane acid such as dimethylol propionic acid or dimethylol butanoic acid, or mixtures thereof.
Of these polybasic acids and polyhydric alcohols, dimer acid and isophthalic acid are particularly preferable as the polybasic acid, and glycol, especially glycol including no ether linkage in the principal chain and having 6-7 carbons in the principal chain and 1,6-hexandiol, in particular, in the case of isophthalic acid being used, are preferable as the polyhydric alcohol. It is to be noted that the principal chain of glycol means a molecular chain sandwiched between two hydroxyl groups and the number of carbons of the principal chain indicate the number of carbons in the molecular chain.
The following two can be cited as the reason why dimer acid and isophthalic acid are preferable as the polybasic acid, and glycol and 1,6-hexandiol are preferable as the polyhydric alcohol. One is that the cyclic ester compound of the dimer acid and the glycol produced by the reaction of dimer acid and glycol is not eluted through the film. Another is that the cyclic ester compound of two molecules of the isophthalic acid and two molecules of the 1,6-hexandiol produced by the reaction of isophthalic acid and 1,6-hexandiol is eluted through the films with difficulty.
For example, when the isophthalic acid and glycol having 5 or less carbons in the principal chain are allowed to react with each other, there may be a case where a cyclic ester compound of two molecules of the isophthalic acid and two molecules of the glycol is produced and the cyclic ester compound is eluted through the film. On the other hand, when isophthalic acid and glycol having 8 or more carbons in the principal chain are allowed to react with each other, there may be a case where a cyclic ester compound of one molecule of the isophthalic acid and one molecule of the glycol is produced and the cyclic ester compound may be eluted through the film. In view
Igarashi Sachio
Sasano Shigetoshi
Bagwell M D.
Seidleck James J.
Takeda Cheical Industries, Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Laminate adhesive does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Laminate adhesive, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laminate adhesive will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2504023