Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-10-26
2001-09-11
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C528S298000, C525S043000, C522S107000
Reexamination Certificate
active
06288146
ABSTRACT:
The present invention relates to the use of specific polyester resins as solvent-free and monomer-free binders for coatings. They are suitable for producing pigmented and unpigmented coating materials and other coatings for metals and nonmetals. Their curing, ie. the transition from the liquid to the solid state in which they are used, takes place by a mechanism which does not give rise to emissions.
Numerous publications relate to unsaturated polyester resins containing dihydrodicyclopentadiene (=DCPD) structural units as a constituent of customary UP resin systems, ie. dissolved in monomeric reactive diluents, generally dissolved in styrene. Masses which can be processed in liquid form, possibly after heating, are stable on storage at processing temperature and whose viscosity is established by way of the novel “DCPD-polyfunctional compounds” without customary monomer reactive diluents containing acrylic or vinylic unsaturation, however, have not hitherto been disclosed.
DE-A-27 08 846 refers to the possibility of reducing styrene in customary UP resin systems by using specific DCPD-containing polyesters.
DE-A-31 07 450 relates to unsaturated polyesters having oligomers of cyclopentadiene as end groups, which can be used as solutions in ethylenically unsaturated monomers to produce moldings and coatings.
EP-A-0 684 284 describes synergistic mixtures of unsaturated polyether ester resins and dicyclopentadiene polyester resins which are dissolved in styrene and are cured in the presence of peroxidic catalysts.
EP-A-0 101 585 relates to unsaturated polyester resins which are modified by the addition of cyclopentadiene onto the double bond of the polyester and are then dissolved in vinyl monomers. However, none of these documents discloses substances which can be processed in liquid form at room temperature or after heating with the use of the novel DCPD-polyfunctional compounds, without the use of monomeric reactive diluents containing acrylic or vinylic unsaturation, as low-emission binders for combined curing by UV light and heat.
To produce low-emission coating compositions for metals and other substrates, powder coatings, aqueous coating systems and liquid, (UV-)radiation-curable coatings are known. Disadvantages, in aqueous systems among others, include the need to evaporate the water, and the effect of the water on the substrates. A known problem in the case of powder coatings is the discrepancy between the requirement for good storage stability of the powders (blocking resistance) and good flow on melting. Liquid (UV-)radiation-curable coatings are systems in which the entire mass of the coating material remains in the finished coating (100% systems), and have good flow and good film properties. Disadvantages include the surface inhibition of the crosslinking reaction by atmospheric oxygen, and the high degree of shrinkage on curing, which in general impairs adhesion. Further disadvantages of known UV systems relate to the often health-damaging potential of the olefinically unsaturated organic compounds used (reactive diluents), such as styrene, vinyltoluene, allyl phthalate and the monomeric or oligomeric acrylic or vinyl esters, both in the course of processing and in the finished coatings, where residual monomers remain.
It is an object of the present invention to avoid the abovementioned disadvantages.
We have found that this object is achieved and these problems are solved by the use of saturated or unsaturated polyesters which can be processed in liquid form at room temperature or after moderate heating, without the addition of solvent, which have structural units according to formulae (I) and/or (II) and which meet the conditions defined below with regard to the melting and viscosity ranges. According to the present invention these ranges can surprisingly be established by the use of the poly-DCPD compounds without the use of monomeric reactive diluents containing vinylic unsaturation.
The possibility of curing saturated polyesters containing structural units of the formulae (I) and (II) using free-radical donors, thermally or by radiation, preferably UV rays, or, with particular preference, by combined curing with radiation and heat, was not hitherto known.
The present invention provides the use of monomer-free, saturated and unsaturated polyester resins or mixtures of saturated and unsaturated polyester resins comprising structural units of the general formulae (I) and/or (II)
as low-emission binders for coatings.
The structural units of the formulae (I) and/or (II) can be incorporated in the form of esters of dihydrodicyclopentadienol with monomeric or polymeric carboxylic acids comprising groups of the formula (III) and/or in the form of esters of oligodihydrodicyclopentadienol with monomeric or polymeric carboxylic acids comprising groups of the formula (IV)
The binders can be monomer-free unsaturated polyester resins comprising structural units of the general formulae (I) and/or (II), or unsaturated polyesters comprising structural units of the formulae (I) and/or (II) can also be used, in addition, if saturated polyester resins are employed.
The structural units of the formulae (I) and/or (II) can be introduced in particular by the use of compounds of the formulae (V) and (VI), ie. the dihydrodicyclopentadienol monoesters of maleic acid and fumaric acid and the monoesters of maleic acid and fumaric acid with oligomeric dihydrodicyclopentadienol
The polyesters to be used in accordance with the invention can be synthesized with the use of alcohols and polyols which are ethoxylated or propoxylated, with the use of mono- or polyhydric alcohols of the polyesterpolyol type, for example polycaprolactone, or with the use of mono- or polyhydric alcohols of the polyetherpolyol type, such as polyethylene oxide, lo polypropylene oxide and/or polytetrahydrofuran.
Moreover, ethylenically unsaturated units can be used additionally when synthesizing the polyester resins, these units including in particular maleic acid and fumaric acid.
A further advantageous embodiment of the novel use is that wherein the binders comprise chemically bonded photoinitiators containing xanthone, thioxanthone and/or phenone structures, preferably those comprising, as chemically bonded photoinitiator, hydroxybenzophenone or benzophenonetetracarboxylic acid incorporated into the polyesters by condensation.
The coatings can be cured by stoving at between 80 and 300° C. or with peroxides, with or without reaction-accelerating co-initiators, such as heavy metal salts and/or C-C-labile compounds, at room temperature or at elevated temperature, if appropriate up to a partially cured B stage, and can then be cured fully at a later point in time.
A further advantage is that the binders can be cured with actinic radiation, preferably UV radiation, the photoinitiators required either being present in chemically bonded form in the binder or having been added to the binder, or both chemically bonded and added photoinitiators can be used.
Similarly, curing with actinic radiation can be combined with curing with peroxides or C-C-labile substances or with purely thermal curing.
A particularly advantageous embodiment consists in the use of binders comprising esterification products of the formulae (V) and (VI) with monofunctional alcohols and/or polyfunctional alcohols and/or the alkoxylation products thereof and/or polyetherpolyols and/or polyesterpolyols such as polyethylene oxide, polypropylene oxide, polytetrahydrofuran and/or polycaprolactone.
A further advantage is if the binders used in accordance with the invention are liquid at room temperature or have softening ranges according to DIN 53180 of below 130° C., preferably below 90° C., particularly preferably below 40° C., with a viscosity of below 100,000 mPas at 100° C., preferably below 30,000 mPas at 75° C., particularly preferably below 5,000 mPas at 50° C., while at the same time being viscosity-stable for at least 24 hours and at a temperature at which they have a viscosity of not more than 10,000 mPas, preferably not more than 2,000 m
Blum Rainer
Loerzer Thomas
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Yoon Tae H.
LandOfFree
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