Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1996-07-23
2001-11-27
Gulakowski, Randy (Department: 1746)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S438000, C525S445000, C525S531000
Reexamination Certificate
active
06323281
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to miscible polymer blends. In particular, the invention relates to blends of epoxy-extended polyetherester resins and commercial polymer resins used in the unsaturated polyester resin industry. The invention provides high-performance thermosets at a reduced cost compared with commercially available high-performance systems.
BACKGROUND OF THE INVENTION
Recently, we described new processes for making polyetherester resins from polyethers (see U.S. Pat. Nos. 5,319,006, 5,436,313, and 5,436,314, and U.S. application Ser. No. 08/619,059, filed Mar. 20, 1996). In each process, a polyether reacts with a cyclic anhydride, a dicarboxylic acid, or a diol diester in the presence of an “insertion” catalyst. The anhydride, dicarboxylic acid, or diol diester inserts randomly into carbon-oxygen bonds of the polyether to generate ester bonds in the resulting polyetherester resin. The polyetherester resin is then combined with a vinyl monomer, preferably styrene, and is cured to produce a polyetherester thermoset. Lewis acids, protic acids having a pKa less than about 0, and metal salts thereof are effective insertion catalysts. The insertion process provides a valuable and versatile way to make a many unique polyetherester intermediates.
More recently (see application Ser. No. 08/608,379, filed Feb. 28, 1996), we extended the insertion technology by developing a process for making high-performance polyetherester resins. These high-performance resins are made by chain extending a polyetherester resin (made by insertion) with a primary diol or a diepoxy compound. The high-performance resins give thermosets with improved high-temperature performance, better tensile and flex properties, and enhanced resistance to aqueous solutions—particularly aqueous acid and caustic solutions—compared with those made using the earlier polyetherester resins.
The polyester industry recognizes the problem of poor water resistance and inadequate tensile and flex properties of many commercial general-purpose polyester systems. In response, the industry has developed two classes of high-performance resins: isophthalate resins (hereinafter also called “iso resins”) and vinyl esters. “Iso resins,” which incorporate recurring units of isophthalic acid, give thermosets with better corrosion resistance compared with those made using general-purpose polyester resins. Because isophthalic acid is relatively expensive, however, and because processing can be time-consuming, iso resins provide better water resistance at a price. In addition, iso resins are still quite susceptible to degradation by aqueous caustic solutions.
Vinyl ester resins currently provide the highest level of physical properties available in the unsaturated polyester industry. When performance must be excellent, and low cost is not so important, vinyl esters are often used. Vinyl esters give thermosets with an excellent overall balance of properties, including high tensile and flex strengths and excellent corrosion resistance. Unfortunately, vinyl esters are by far the most expensive resins. In addition, vinyl ester resins are not easily thickened, and this limits their usefulness in SMC applications.
Another problem with the more expensive varieties of resins now available is that they are often incompatible with less expensive resins. For example, vinyl ester resins are not generally compatible with general-purpose resins. Thus, blending offers no value to a formulator who might wish to boost physical properties of a general-purpose resin by blending in vinyl ester, or to cheapen a vinyl ester formulation by adding some general-purpose resin.
Resin blends that can improve thermoset properties and/or reduce costs are needed. The excellent physical properties, low cost, and unique structure of epoxy-extended polyetherester resins prompted us to investigate blends of these resins with commercial polyester resins.
SUMMARY OF THE INVENTION
The invention is a miscible resin blend. The blend comprises an epoxy-extended polyetherester resin and one or more polymer resins selected from vinyl esters, isophthalate resins, orthophthalate resins, dicyclopentadiene (DCPD) resins, bisphenol A resins, propylene glycol-maleate resins (PG-maleate resins), and chlorendic anhydride resins.
Preferably, the epoxy-extended polyetherester resin is made by (1) reacting a polyether polyol with a dicarboxylic acid, an anhydride, or a diol diester in the presence of an insertion catalyst to produce an acid-terminated polyetherester resin; and (2) reacting the acid-terminated polyetherester resin with an epoxy compound to produce the epoxy-extended polyetherester resin.
We surprisingly found that epoxy-extended polyetherester resins have excellent compatibility with a wide range of commercial polyesters. Blends of epoxy-extended polyetherester resins and vinyl ester resins are miscible and give thermosets with excellent properties at a reduced cost compared with vinyl ester systems. In addition, these resin blends can be thickened easily, and are therefore useful in SMC applications. Iso resin blends with the epoxy-extended polyetherester resins are also miscible, and give excellent thermosets with dramatically improved KOH resistance compared with that of iso systems. In sum, the unusual compatibility of epoxy-extended polyetherester resins with a wide variety of commercial polyester resins makes them versatile blending resins for reducing costs and/or improving thermoset properties.
DETAILED DESCRIPTION OF THE INVENTION
The miscible resin blends of the invention comprise an epoxy-extended polyetherester resin and one or more polymer resins selected from the group consisting of vinyl esters, isophthalate resins, orthophthalate resins, dicyclopentadiene (DCPD) resins, bisphenol A resins, PG-maleate resins, and chlorendic anhydride resins.
Epoxy-extended polyetherester resins are reaction products of a polyetherester resin and an epoxy compound, preferably a diepoxy compound. The epoxy compound links polyetherester chains by reacting with carboxylic acid end groups of the polyetherester resin.
Preferably, the epoxy-extended polyetherester resin is prepared in two steps. First, a polyether polyol reacts with a dicarboxylic acid, an anhydride, or a diol diester in the presence of an insertion catalyst to produce an acid-terminated polyetherester resin. Second, the acid-terminated polyetherester resin reacts with an epoxy compound to produce the epoxy-extended polyetherester resin.
Polyether polyols suitable for use in this first step are those derived from ring-opening polymerization of cyclic ethers such as epoxides, oxetanes, oxolanes, and the like, and mixtures thereof. The polyols have oxyalkylene repeat units (—O—A—) in which A has from 2 to 10 carbon atoms, preferably from 2 to 4 carbon atoms. Suitable polyether polyols include, for example, polyoxypropylene polyols, polyoxyethylene polyols, ethylene oxide-propylene oxide copolymers, polytetramethylene ether glycols, and the like, and mixtures thereof. Typically, the polyols have average hydroxyl functionalities from about 2 to about 8, and number average molecular weights from about 250 to about 25,000. Preferred polyether polyols have an average hydroxyl functionality within the range of about 2 to about 6, a hydroxyl number within the range of about 28 to about 260 mg KOH/g, and a number average molecular weight within the range of about 400 to about 12,000. Particularly preferred are polyoxypropylene diols and triols having a number average molecular weight within the range of about 1000 to about 4000. Other examples of suitable polyols appear in U.S. Pat. No. 5,319,006, the teachings of which are incorporated herein by reference.
Anhydrides useful in the process are cyclic anhydrides, which may be saturated or unsaturated. “Cyclic” anhydrides contain the anhydride functionality within a ring. Examples include phthalic anhydride and maleic anhydride. “Saturated” anhydrides contain no ethylenic unsaturation, but may contain aromatic rings. Examples include phthalic anhydride, prop
Cai Gangfeng
Klang Jeffrey A.
McFarland Jeffrey M.
Yang Lau S.
Arco Chemical Technology L.P.
Gulakowski Randy
Schuchardt Jonathan L.
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