| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | March 30, 1993 |
| PATENT TITLE |
High molecular unsaturated polyester |
| PATENT ABSTRACT | A high molecular weight unsaturated polyester having a number-average molecular weight of 5,000 or greater, the polyester being represented by a general formula: ##STR1## wherein G denotes a glycol residue, m denotes 1 to 10, n denotes 1, and M denotes a number corresponding to a number-average molecular weight greater than 5,000. The high molecular unsaturated polyester of the present invention is an unsaturated polyester having a large molecular weight unattainable by conventional methods, and can find wide application by utilizing its improved physical properties |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | November 18, 1991 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A high molecular weight unsaturated polyester having a number-average molecular weight of 5,000 or greater, said polyester being represented by a general formula: ##STR3## wherein G denotes a glycol residue, m denotes 1 to 10, n denotes 1, and M denotes a number corresponding to a number-average molecular weight greater than 5,000. 2. A high molecular weight unsaturated polyester resin formed by blending, in said high molecular weight unsaturated polyester according to claim 1, a monomer copolymerizable with said polyester. 3. A method of producing a high molecular weight unsaturated polyester having a number-average molecular weight of 5,000 or greater, said method comprising the steps of: esterifying an .alpha.,.beta.-unsaturated polybasic acid, a saturated polybasic acid and a glycol in the presence or absence of a catalyst for a glycol elimination reaction until the acid value thereof is reduced to 15 or less; adding a catalyst for a glycol elimination reaction when no glycol elimination reaction catalyst is present in the preceding step; and effecting a glycol elimination reaction at a reduced pressure of 5 Torr or less. 4. A method according to claim 3, wherein the catalyst for a glycol elimination reaction comprises an organic titanium compound. 5. A method according to claim 4, wherein the organic titanium compound is selected from the group consisting of tetrabutyl titanate, tetrapropyl titanate and acetyl acetonate of titanium. 6. A method according to claim 4, wherein 0.01 to 0.05 part by weight of the organic titanium compound is used for 100 parts by weight of unsaturated polyester. 7. A method according to claim 3, wherein the method comprises continuing the esterifying until the acid value is reduced to 10 or less. 8. A method according to claim 3, wherein the glycol elimination reaction is effected at a reduced pressure of 1 Torr or less. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an unsaturated polyester having a large molecular weight and which is useful in the fields of fiber reinforced plastics, linings and castings and a high molecular unsaturated polyester made by blending with this unsaturated polyester a monomer that is copolymerizable therewith. 2. Discussion of the Background As is well known, unsaturated polyester resins (polyester resins), known as typical radical curing type resins, are widely used as fiber reinforced plastics (hereinafter referred to as FRP), coating materials, lining materials, casting materials and the like. With the expanded use of unsaturated polyester resins, physical properties required of the resins have, of course, become of a high degree and various methods for improving the properties of this kind of resin have therefore been practiced. For example, methods of improving mechanical properties based on increasing the molecular weight by reaction with diisocyanate, of improving coating performance by reaction with an epoxy resin, and of providing a toughness by using a rubber-like polymer are being practical. However there is no movement visible at the publicly disclosed level towards solving the problems by increasing the molecular weight of an unsaturated polyester (unsaturated alkyd) constituting an unsaturated polyester resin. This may be because it is thought that the molecular weight (hereinafter expressed as number-average molecular weight) is at most 2,000 to 2,500 and that it would be very difficult to exceed 3,000 because of gelation during reaction. ln fact, for desired practicality of resulting resins in terms of handling relating to viscosity, curing, moldability and other factors, it is difficult to crack the barrier of a molecular weight of 3,000 only by the esterification reaction ordinarily used for manufacture of unsaturated polyester resins. An object of the present invention is to provide a novel high molecular unsaturated polyester having improved physical properties and which is widely applicable. SUMMARY OF THE INVENTION The inventors of the present application have found that the molecular weight of a high molecular unsaturated polyester can be increased, under conditions described below, to 5,000 or greater which has heretofor been considered unattainable. The present invention is based on a finding that a polyester resin having an unsaturated polyester structure in a particularly low reactivity region (of a type such that the proportion of .alpha.,.beta.-unsaturated polybasic acid used is smaller, that is, m in the following general formula is greater) and having a molecular weight as defined below has improved physical properties in comparison with low molecular unsaturated polyester resins having a molecular weight of 3,000 or less even if the compositions are the same. That is, according to one aspect of the present invention, there is provided a high molecular unsaturated polyester having a number-average molecular weight of 5,000 or greater, and is expressed by a general formula: ##STR2## (where G denotes a residue of glycol, m denotes 1 to 10, n denotes 1, and M denotes a number corresponding to a number-average molecular weight greater than 5,000). According to another aspect of the present invention, there is provided an unsaturated polyester resin formed by blending the above high molecular unsaturated polyester with a monomer copolymerizable therewith. According to still another aspect of the present invention, there is provided a method of producing a high molecular unsaturated polyester having a number-average molecular weight of 5,000 or greater, the method comprising the steps of: a) esterifying an .alpha.,.beta.-unsaturated polybasic acid, a saturated polybasic acid and a polyhydric alcohol by adding or without adding a catalyst for glycol elimination reaction until the acid value thereof is reduced to 15 or less. adding a catalyst for glycol elimination reaction in case of adding no glycol elimination reaction catalyst in the preceding step; and effecting glycol elimination reaction at a reduced pressure of 5 Torr or less. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a GPC chromatogram of a low molecular unsaturated polyester in accordance with Example 1; FIG. 2 is a GPC chromatogram of a high molecular unsaturated polyester in accordance with Example 1; FIG. 3 is a GPC chromatogram of a low molecular unsaturated polyester in accordance with Example 4; FIG. 4 is a GPC chromatogram of a high molecular unsaturated polyester in accordance with Example 4; FIG. 5 is a GPC chromatogram of a low molecular unsaturated polyester in accordance with Example 5; FIG. 6 is a GPC chromatogram of a high molecular unsaturated polyester in accordance with Example 5; FIG. 7 is a GPC chromatogram of an unsaturated polyester in accordance with Example 7; FIG. 8 is a GPC chromatogram of an unsaturated polyester in accordance with Comparative Example 3; FIG. 9 is a diagram of IR analysis of an unsaturated polyester formed in accordance with Example 7; FIG. 10 is a GPC chromatogram of a low molecular unsaturated polyester formed in process for Example 10; and FIG. 11 is a GPC chromatogram of a high molecular unsaturated polyester formed in accordance with Example 10. DETAILED DESCRIPTION OF THE INVENTION Raw-materials from which the high molecular unsaturated polyester in accordance with the present invention is composed are the same as those used in the conventional unsaturated polyester resin manufacture process. The following are examples of such materials: a) Practical .alpha.,.beta.-unsaturated polybasic acids and acid anhydrides thereof: maleic anhydride, fumanic acid and the like; and b) Saturated polybasic acids having a benzene nucleus: phthalic anhydride, isophthalic acid, terephthalic acid, dimethyl terephthalate ester and the like. .alpha.-glycols in polyhydric alcohols used together with the above polybasic acids are ethylene glycol, propylene glycol and the like. Diethylene glycol, dipropylene glycol, butanediol 1,3, butanediol 1,4, neopentyl glycol, pentanediol 1,5, hexanediol 1,6 and polyhydric alcohols, such as those listed below, having a high boiling point and difficult glycol interchange can be used as additional materials. Bisphenol hydride A, adduct of bisphenol A with ethylene oxide, adduct of bisphenol A with propylene oxide, glycerol diallyl ether, trimethylolpropane-mono, and diallyl ether can be used as polyhydric alcohols. Alkylenemonoepoxy compounds, e.g., ethylene oxide, propylene oxide, epichlorohydrin, phenylglycidyl ether, allylglycidyl ether, can also be used. In a process for manufacturing the unsaturated polyester in accordance with the present invention: A) esterification is first effected so that the acid value of unsaturated polyester is 15 or less and, if no glycol elimination reaction catalyst is added, at this stage; B) a catalyst for glycol elimination reaction is then added, and C) the glycol elimination reaction is promoted at a reduced pressure of 5 Torr or less, more preferably 1 Torr or less. The first-stage esterification is effected in an inert gas flow at a temperature of 160.degree. to 230.degree. C. to substantially compose unsaturated polyester having an acid value of 15 or less, more preferably 10 or less. At this time, it is necessary for the unsaturated polyester to have a molecular weight of 1,000 or greater. The second-stage glycol elimination reaction (ester interchange reaction) is effected under the presence of a catalyst at a very low pressure. If at this time the acid value exceeds 15, the glycol elimination reaction is not sufficiently effected and it is difficult to compose a high molecular unsaturated polyester. As the catalyst, the organic titanium compound can be used. For example, it is tetrabutyl titanate, tetrapropyl titanate or acetyl acetonate of titanium. The amount of this catalyst is 0.01 part by weight or more, preferably 0.01 to 0.5 part by weight, more preferably 0.1 to 0.3 part by weight for 100 parts by weight of unsaturated polyester. A monomer for dissolving the unsaturated polyester to form a polyester resin is typically a styrene. Other examples of this monomer are vinyl toluene, methyl methacrylate, diallyl phthalate and diallyl terephtalate. The high molecular saturated polyester resin in accordance with the present invention can be used in the same field as the conventional ordinary-type unsaturated polyester resins. Needless to say, it can be used together with reinforcement fibers, fillers, colorants, mold release agents and stabilizers |
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| PATENT PHOTOCOPY | available on request |
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