Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-02-16
2003-11-25
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S270000, C524S271000, C525S054420, C528S395000
Reexamination Certificate
active
06653398
ABSTRACT:
This invention relates to a novel polyester tackifier, adhesive compositions comprising the tackifier and methods of preparation. More specifically, the polyester tackifier is obtainable by polymerising a mixture comprising a diacid or derivative thereof, a diol, and at least 6 molar % of an organic monofunctional compound, wherein the mixture is essentially free from compounds comprising more than two carboxylic acid groups or alcohol groups.
BACKGROUND OF THE INVENTION
Synthetic polymers such as acrylic polymers have, for the most part, replaced naturally occurring materials such as animal glues, starches and vegetable gums in many adhesive applications. The key to this replacement was the development and use of tackifier resins in the formulation with synthetic polymers, because they give the system the ability to wet the substrate surface and thus form a strong bond. Without tackifiers in the adhesive formulation, the synthetic polymers have low tack and peel adhesive performance.
Various resinous materials have been suggested as tackifiers for synthetic polymers. Examples of materials suggested include rosin, disproportionated rosin, rosin esters such as glycerol esters of rosin and pentaerythritol esters of rosin, aliphatic hydrocarbon resins from petroleum, aromatic petroleum resins, dicyclopentadiene (DCPD) resins, terpene resins, terpent/phenol resins and cumarone/indene resins.
Tackifiers are resins that can be considered as high viscosity solvents for the base polymer. The term tackifier therefore, cannot be given to any material unless we relate that material to the product that it tackifies.
Acrylic polymer compositions have long been used as adhesive compositions, particularly in pressure sensitive adhesive (PSA) compositions. Common PSA compositions include a high-molecular-weight acrylic base polymer and a tackifying resin and when required, plasticizer, stabilizer, antioxidant, filler, coloring agent and the like. PSA compositions should have a high initial tack so that the adhesive surface merely needs to be contacted and pressed to the surface to achieve bonding. There should be little or no requirement to hold the adhesive and substrate in position for any significant time while a bond develops.
In developing adhesive formulations one seeks the optimum combination of several adhesive properties and since it is not generally possible to achieve the optimum for every property it is necessary to obtain the best balance of properties for the particular use in mind. In e.g. PSA compositions which are used in the label industry one tries to optimise the loop tack and peel and at the same time provide an adhesive whose component will not migrate during storage.
Nowadays mainly rosin derivatives, such as disproportionated rosin acids, and hydrocarbon resins are commercially used as tackifiers for adhesive compositions comprising acrylic polymers. The rosin derivatives have been preferred due to better compatibility with acrylics.
Initially most important were the solvent acrylics, but environmental, health and safety needs of industry have resulted in dramatic growth in water borne adhesive compositions comprising acrylic polymers. With increasing desirability of water borne systems and often their demonstration of significant performance enhancements with tackifier resins, new tackifier resins suitable for these systems are being sought.
U.S. Pat. No. 5,120,781 discloses tackifiers for hot melt adhesive compositions. The tackifiers are produced by reacting rosin and a polyhydric alcohol under conditions effective to substantially complete the esterification reaction. The resulting reaction product is then reacted with an aromatic dibasic acid providing a tackifier with a content of rosin above 78 weight %.
U.S. Pat. No. 4,981,939 refers to a binder for preparing toners which are used for developing electrostatic images formed in the process of electrography. The toner comprises as the main component a polyester composed of a polybasic acid component and a polyhydric alcohol component and a rosin modified polyhydric alcohol. The rosin modified polyhydric alcohol is produced by reacting a polyhydric alcohol having three or more hydroxyl groups with a rosin resulting in a polyester network (cross-linking).
WO 9942508 relates to low viscosity aromatic polyester polyols prepared by reacting a phthalic acid based material with diethylene glycol, a higher functional polyol having an average functionality of greater than two and a long chain alkyl acid, ester or oil. The resulting aromatic polyester polyol is a branched polyester.
U.S. 3,438,918 refers to rubber compositions obtained by reacting polyhydric alcohols, polybasic acids and oils.
Thus one advantage of the present invention is to provide a tackifier which is compatible with water borne pressure sensitive adhesive compositions and hot melt pressure sensitive adhesive compositions.
The further advantage with the present invention is the improvement of overall adhesive properties of adhesive compositions and specifically improving the properties of loop tack and peel and at the same time provide an adhesive (composition) whos component(s) will not migrate during storage.
A still further advantage with the present invention is to provide a polyester tackifier comprising a minimum amount of rosin derived from natural sources thereby reducing the cost of production, i.e. a polyester which is capped at both ends with a monofunctional compound (a polyester containing not more than two rosin residues).
Another advantage with the present invention is to provide a straight chain polyester resin being solid or liquid.
Still further advantages of the present invention are disclosed by the following specification.
SUMMARY OF THE INVENTION
The present invention relates to a polyester tackifier and a pressure sensitive adhesive composition comprising the polyester tackifier according to the claims. More specifically, the present invention relates to a polyester tackifier which is obtainable by polymerising a mixture comprising a diacid or derivative thereof, a diol, and at least 6 molar % of an organic monofunctional compound, wherein the mixture is essentially free from compounds comprising more than two carboxylic acid groups or alcohol groups and a pressure sensitive adhesive composition comprising said polyester tackifier. The present invention also relates to the use of the polyester tackifier, an aqueous pressure sensitive adhesive composition, a hot melt pressure sensitive adhesive composition and a method for manufacturing a polyester tackifier.
DETAILED DESCRIPTION OF THE INVENTION
The polyester tackifier is suitably obtained by esterification of at least one diacid or derivative thereof, at least one diol, and at least 6 molar % of an organic monofunctional compound, wherein the mixture is essentially free from compounds comprising more than two carboxylic acid groups or alcohol groups, i.e. suitably essentially free from compounds comprising more than two functional groups enabling the compounds of taking part in the polymeric esterification reaction. The diols and diacids preferably will produce an alternating linear
on-branched condensation polymer which is terminated at both ends by the organic monofunctional compound, the latter functioning as a chain stopper, i.e. capper.
The diacids which can be used in the present invention are organic diacids such as organic dicarboxylic acids or derivatives thereof. By derivatives thereof is meant acid anhydrides or any other acid capable of forming an ester moiety in the polyester. Suitably, the dicarboxylic acids are aliphatic, cyclic or aromatic, whereby aromatic dicarboxylic acids or derivatives thereof are preferred. Even more preferred are aromatic dicarboxylic acids having the dicarboxylic acid moieties in para or ortho position such as terephthalic acid and phthalic acid. Aromatic dicarboxylic acids having the diacid moiety in the ortho position are especially favourable such as phthalic acid. The aliphatic diacids can be branched or linear comprising from 4 up to
Aarts Patrick Peter Mario
Hazen John
Akzo Nobel N.V.
Burke Michele J.
Parker Lainie E.
Szekely Peter
LandOfFree
Polyester tackifier and adhesive composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyester tackifier and adhesive composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyester tackifier and adhesive composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3135241