Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-02-29
2001-07-31
Boykin, Terressa M (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S176000, C528S271000
Reexamination Certificate
active
06268464
ABSTRACT:
The invention relates to modified unsaturated polyester resins with a higher molecular weight, a low viscosity and high solubility especially in reactive diluents. The invention also relates to a method for the manufacture of such unsaturated polyester resins and to use thereof.
Unsaturated polyesters are polymers having structural units linked by ester groupings, and they can be manufactured by the condensation of carboxylic acids with polyhydric alcohols. Low molecular weight unsaturated polyesters are usually produced from maleic anhydride with diethylene glycol or, alternatively, other carboxylic acids or anhydrides such as fumaric acid, and glycols such as propylene glycol are used. Typically, the obtained unsaturated polyesters are in the form of a rather viscous oil. Low molecular weight unsaturated polyesters will crosslink in the presence of a peroxide by copolymerization with reactive diluents. Unsaturated polyester resins typically contain volatile unsaturated organic monomers such as styrene as the reactive diluent. In commercially available unsaturated polyester resin applications, up to 50% of styrene or other vinyl monomers are used. During curing, some of the organic monomer is usually lost in the atmosphere, 10-20% of the total amount of the monomer may be lost during resin spray-up and lamination and 30-50% during gelcoat spraying and thus these emissions cause occupational safety hazards and are also a problem because of environmental considerations. In most countries legislation introduced in recent years requires a reduction in the amount of volatile organic compounds (VOC) which may be released to the atmosphere. Several methods have been proposed for reducing VOC emissions, for example the replacement of the reactive diluent with a less volatile reactive diluent. This approach has led to slower curing times and/or incomplete curing at normal ambient temperatures. Another approach is a reduction in the amount of the reactive diluent in the composition. This approach has led to an increase in the viscosity of the resin beyond useable values. If the viscosity increase is compensated for by the use of a lower molecular weight polyester then poor final product properties will result. Still another approach has been the use of a suppressant which reduces the loss of VOCs. The suppressants are often waxes which may lead to a reduction in the interlaminar adhesion of laminating layers. On the other hand, requirements for the mechanical properties and for the quality of polyester resins and of their applications are constantly tightening, which can be seen especially in the field of marine applications. Thus, there is a clear need for polyester resins and their applications with low reactive diluent emissions and with superior properties and quality.
An unsaturated polyester resin is presented in DE 25 27 675 wherein the polyester resin comprises an &agr;,&bgr;-ethylenically unsaturated polyester, the terminal groups of which comprise a high amount of residues of monoalcohols and a copolymerizable monomer. High amounts of monoalcohols yield rather expensive polymers with shorter molecular chains and poor mechanical properties. Additionally, the use of maleic anhydride as the sole source for a carboxylic acid derivative leads to resins with inferior chemical resistance and mechanical properties.
European patent publication EP 0 475 661 relates to unsaturated polyester resins which have improved hydrolytic stability and low molecular weights (Mw) of about 300 to 2500, and which are chain-stopped or endcapped with monofunctional alcohols or acids. The chain-stopped resins can be modified by addition of polyisocyanate and hydroxy acrylate to prepare resins for artificial marble, artificial onyx, fiber glass reinforced products, laminates, sheet moulding compounds and resin transfer moulding applications. Alternatively, the resins can also be modified by adding a polyisocyanate, a hydroxy acrylate and a dicyclopentadiene based unsaturated polyester resin to produce a composition suitable for low profile marine applications. These unsaturated polyesters are prepared by the condensation of dicarboxylic acids or anhydrides with polyhydric alcohols in the presence of chain-stopping monofunctional acids or alcohols.
U.S. Pat. No. 5 688 867 describes a polyester resin comprising (A) from about 5 wt % to about 50 wt % of a reactive diluent and (B) from about 50 wt % to about 95 wt % of an unsaturated polyester resin prepared from at least one polycarboxylic acid anhydride or ester, at least one polyhydric alcohol, and at least one component selected from a group consisting of (i) from about 0.5 mol % up to about 8 mol % of polyhydric alcohol having at least three hydroxyl groups, and at least one transesterification catalyst, (ii) from about 2 mol % up to about 12 mol % of a reaction product of a polyol and a fatty carboxylic acid, and (iii) from about 2 mol % up to about 12 mol % of a fatty reactant selected from the group consisting of a fatty primary alcohol, a fatty epoxide, a fatty monocarboxylic acid and mixtures thereof, wherein each member of the group has up to about 100 carbon atoms. The invention also relates to mixtures of polyester resins with conventional polyester resins. This invention provides resins and methods which have a low emission of volatile organic compounds.
An object of the present invention is to provide unsaturated polyester resins which have a higher molecular weight, a low viscosity and which are readily soluble in reactive diluents. Another object of the present invention is to provide unsaturated polyester resins for applications such as general purpose resins and gelcoats with reduced volatile organic compound emissions in order to reduce the risk of occupational safety hazards and environmental concerns. Additionally methods for the manufacture of such unsaturated polyester resins and unsaturated polyester systems including products and applications, with good physical properties such as good mechanical strength, weathering resistance and with good final product properties are desired, especially for marine applications with very strict requirements.
Characteristic features of the unsaturated polyester resins, of the manufacture thereof and of the use according to the invention are stated in the claims.
It has been found that the above-mentioned objects can be reached with the following solution. In accordance with the present invention unsaturated polyester resins are prepared by condensation of at least two carboxylic acids or derivatives thereof and at least one of them is an aromatic carboxylic acid or a derivative thereof, and at least one of them is an unsaturated carboxylic acid or a derivative thereof, with at least two diols and at least one of them is 2,2,4-trimethyl-1,3-pentanediol or 2-butyl-2-ethyl-1,3-propane diol, in the presence of at least one monoalcohol, and the obtained unsaturated polyester or mixtures of unsaturated polyesters are diluted in a reactive diluent or in mixtures of reactive diluents. Optionally one or more other carboxylic acids and one or more polyhydric alcohols may also be used as well as one or more modifying chemicals. This specific combination of starting materials i.e. part of the carboxylic acids are unsaturated carboxylic acids and part are of aromatic nature, part of the diols are specified aliphatic branched diols, used with combination of a monoalcohol(s), yields the cured products the desired properties.
Suitably unsaturated carboxylic acids or derivatives thereof, such as maleic acid, maleic anhydride and fumaric acid and the like are used in an amount of at least 50 mol % of total amount of carboxylic acids. Preferably the aromatic carboxylic acid or a derivative thereof is phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid or hexa-hydrophthalic anhydride. Suitable other carboxylic acids are adipic acid, trimellitic acid, trimellitic anhydride, dimethylmalonic acid, hydroxypivalic acid, 1,4-cyclohexanedicarboxylic ac
Keinänen Kari
Wigington Glenn
Birch & Stewart Kolasch & Birch, LLP
Boykin Terressa M
Neste Chemicals Oy
LandOfFree
Unsaturated polyester resins does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Unsaturated polyester resins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Unsaturated polyester resins will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2455743