Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2002-01-31
2003-09-09
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C428S411100, C428S423500, C428S423700, C528S271000
Reexamination Certificate
active
06617417
ABSTRACT:
The invention relates to unsaturated polyester resins and more particularly polyester resin compositions curable at room temperature and comprising divinyl ethers, which compositions are specially suitable for gelcoats, lamination resins and applications where thicker layers of the product are required.
Various vinyl and divinyl ethers have been used as monomer replacing agents in different polyester formulations of the state of the art. A benefit which is achieved by using vinyl ethers, is the replacement of more harmful monomers with non-hazardous vinyl compounds, which are sufficiently reactive under appropriate curing conditions and which can be cured as part of the finished product. One of the major problems relating to the applicability of these resin compositions in normal unsaturated polyester resin concerns curing. In most of the examples presented in literature, the resins can be cured only by radiation. U.S. Pat. No. 5,360,863 describes the use of vinyl ethers as an alternative to acrylates and methacrylates in radiation curable unsaturated polyester compositions. This publication discloses the replacing of volatile monomers like styrene or low molecular weight methacrylates/acrylates by vinyl ethers but the compositions presented in the patent are only radiation curable. Similarly, EP patent 322 808 describes the use of divinyl ethers with ethylenically unsaturated polyesters in radiation curable compositions. An additional feature of the invention in this publication is to allow divinyl ether to react to iso-cyanates in order to obtain vinyl ether modified polyurethane intermediates. WO 90/01512 describes more generally the use of vinyl ethers in photo-curable compositions.
Curing by radiation sets great limitations for vinyl ether compounded polyesters in applications, such as construction, because the versatility of applications and the thickness of moulded layers are significantly limited. Moulds of larger size are difficult or impossible to expose to any radiation and even if the moulded parts could be cured by radiation, radiation does not penetrate the thick layers of reinforced materials. For the above mentioned reasons the typically used unsaturated polyester formulations containing vinyl ethers are suitable only for UV (ultra violet) or EB (electron beam) curable coatings.
EP application 0582909 discloses at room temperature radical curable compositions specially suitable for thin films and coatings of approx. 90 &mgr;m thickness which compounds comprise unsaturated polyesters based on unsaturated dicarboxylic acids and unsaturated glycolic oxalkylated 2-buten-1,4-diols, and (meth)acrylates. Compounds with vinyl ether groups may also or alternatively used. By using the unsaturated glycolic components the density of unsaturation is raised thus increasing the total reactivity of the polyesters sufficient for thin coatings. Additionally the compositions comprise known additives. DE application 19711410 discloses compositions for impregnation, filling and coating of electrotechnical and electronic building parts and for impregnation or isolation materials. The composition which is suitable for impregnation and for coating with thin films, comprises a polyester component A1) which contains as building blocks dihydrodicyclopentadienyl units and/or oligo-dihydrodicyclopentadienyl units, a vinyl ether component (A2) and an additional polymer component (A3) and other additives. These dicyclopentadienyl based polyester resins are cured by methods requiring photo-initiation or thermal initiation followed by curing at elevated temperatures or under radiation.
Thus, there clearly exists a need for unsaturated polyester resin compositions for gelcoats, for lamination purposes and for composites which compositions comprise vinyl ethers and which are curable at room temperature under normal conditions.
An object of the present invention is to provide unsaturated polyester resin compositions which comprise divinyl ethers and which compositions are curable under normal conditions at room temperature. A further object of the present invention is to provide a method for the manufacture of such polyester resin compositions, and a still further object of the invention is the use of said compositions.
The characteristic features of the unsaturated polyester resin compositions comprising divinyl ethers, the method for the manufacture thereof and the use thereof are set forth in the claims.
In accordance with the invention, the unsaturated polyester resin composition comprises at least one unsaturated polyester and at least one divinyl ether, and the curing of the composition may be conveniently performed with radical curing such as peroxide initiator systems under normal curing conditions at room temperature. The curing may be enhanced by using in the formulation a portion of at least one modified polyester such as methacrylate or acrylate modified polyester, and optionally a catalytic amount of a copromoter. Various divinyl ethers or mixtures thereof may be used for partly or totally replacing of monomers, in particular harmful monomers, such as styrene, in unsaturated polyester resin compositions.
The unsaturated polyester resin compositions comprising divinyl ethers are compounded of at least one and preferably two to four unsaturated polyester. Suitable starting materials for the manufacture of normal or modified unsaturated polyesters are listed in the following. As sources of unsaturation, ethylenically unsaturated acids such as maleic acid, fumaric acid, maleic anhydride, derivatives thereof or mixtures thereof are used in an amount of at least 10 mol-%, preferably at least 20 mol-%. As other acids may be used benzoic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, terephtalic anhydride, adipic acid, 1,2-cyclohexyl dicarboxylic acid and 1,4-cyclohexyl dicarboxylic acid. For replacing partially or totally the said ethylenically unsaturated acids, optionally methacrylic acid or acrylic acid may be used in an amount of not more than 40 mol-% and preferably not more than 30 mol-% calculated from the amount of all components, for raising the degree of unsaturation and the reactivity of the polyester resin.
Suitable alcohols required as other components in the unsaturated polyester are monoalcohols, diols, triols, aliphatic alcohols and aromatic alcohols. Preferred saturated aliphatic diols and triols have a general formula (I)
wherein
X is C
1
-C
4
, (CH
2
—CH
2
—O)n or
and n=1,2,3;
R is H, —CH
2
OH, —CH
3
, —CH
2
CH
3
, —CH
2
CH
2
CH
3
or —CH
2
CH
2
CH
2
CH
3
and
R′ is H, —CH
2
OH, —CH
3
, —CH
2
CH
3
, —CH
2
CH
2
CH
3
or —CH
2
CH
2
CH
2
CH
3
.
Particularly preferred alcohols are 2-ethyl hexanol, benzyl alcohol, 2-phenylethyl alcohol, ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butane diol, 2-methyl-1,3-propane diol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propane diol, 1,6-hexane diol, trimethylol propane and tri-methylol ethane.
The alcohols may also be partly replaced by glycidyl compounds in order to obtain low molecular weight methacrylate or acrylate modified or terminated polyesters. Suitable glycidyl compounds are glycidyl methacrylate and glycidyl acrylate. At most 80 mol-% of alcohols can be replaced by glycidyl compounds and preferably not more than 60 mol-%.
The ratio of acids to alcohols generally used in polyesters of the state of the art may be applied.
The resins are processed in conventional reactors for polyesters until an acid value of 5-65 is reached and excess water is removed during the reaction. During the addition of endcappers, if any, which here refer to glycidyl compounds, the reaction temperature may be decreased, if necessary.
The unsaturated polyester resin composition in accordance with the invention containing divinyl ether comprises:
50-90 wt-%, preferably 58-80 wt-% of at least one, preferably two to four normal unsaturated polyester and/or modified unsaturated polyester;
not more than 30 wt-%, preferably not more than 20 wt-% of st
Airola Karri
Färm Outi
Mahbub Paul
Valtonen Eija
Ashland Inc.
Birch & Stewart Kolasch & Birch, LLP
Boykin Terressa M.
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