POLYESTER BLENDS

Abstract: Blends of a hydroxy-functional polyester and a polyalkylene oxide, a polyester polyol or an aliphatic polyester having increased moisture sensitivity and decreased break stress and modulus compared with unblended hydroxy-functional polyesters and are prepared by conventional dry blending methods using conventional means such as a barrel mixer or tumble mixer or by melt blending in an appropriate apparatus, such as a Banbury typed internal mixer. The blends can be used as hot-melt adhesives, adhesive tackifiers, plasticizers, heat-curable adhesives and heat-curable coatings.

Description: POLYESTER BLENDS This invention relates to polyester blends, more particularly to blends of hydroxy-functional polyesters, and to processes for preparing the same. Hydroxy-functional polyesters are known in the art and are described, for example, in U.S. Patents 5,496,910; 5,171 ,820 and 5,138,022. Blends of hydroxy-functional polyesters with other thermoplastic polyesters are also known, as described in Japanese Patents Shotsugan Kokai 62-25151 and 62-15255. These are immiscible blends which may require compatibilizers to maximize adhesion between phases to insure acceptable physical properties, as described in Japanese Patents Shotsugan Kokai 64-210454. Miscible blends of hydroxy-functional polyesters with thermoplastic polyesters, such as poly(ethylene terephthalate) (PET) are described in U.S. Patent 5,134,201. However, these hydroxy- functional polyesters and blends thereof are not suitable for certain applications, such as hot-melt adhesives, adhesive tackifiers, plasticizers, heat-curable adhesives and heat- curable coatings. In one aspect, the present invention is a composition comprising a blend of a hydroxy-functional polyester and a polyalkylene oxide, a polyester polyol or an aliphatic polyester. The blends of the present invention can be used as hot-melt adhesives, adhesive tackifiers, plasticizers, heat-curable adhesives and heat-curable coatings. Some of these materials are biodegradable and are therefore suitable for application to compostable end-products. The hydroxy-functional polyester which can be employed in the practice of the present invention is a poly(hydroxy ester) or a poly(hydroxy ester ether) having repeating units represented by the formula: - θ 2 C- RL-COs- R 3 -O- R 4 -O- R 3 - wherein R is a divalent organic moiety which is primarily hydrocarbon; R 3 is: and R 4 is: wherein R 2 and R 6 are independently divalent organic moieties which are primarily hydrocarbon; R 5 is hydrogen or alkyl and n is from 0 to 100. In the preferred polymers, R 1 , R 2 and R 6 are independently alkylene, cycloalkylene, alkylenearylene, alkyleneoxyalkylene, poly(alkyleneoxyalkylene), alkyleneamidealkylene, poly(alkyleneamidealkylene), alkylenethioalkylene, poly(alkylenethioalkylene), alkylenesulfonylalkylene, poly(alkyienesulfonylalkylene), arylene, dialkylenearylene, diaryleneketone, diarylenesulfone, diarylene oxide, alkylidene-diaryiene, diarylene sulfide, or a combination of these moieties, optionally substituted with at least one hydroxyl group. In the more preferred polymers, R 1 is methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1 ,4-cyclohexylene, 1 ,3-cyclohexylene or 1 ,2-cyclohexylene, optionally substituted with at least one hydroxyl group; and R 2 and R 6 are independently methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1 ,4-cyclohexylene, 1 ,3-cyclohexylene or 1 ,2-cyclohexylene, optionally substituted with at least one hydroxyl group. More preferably, R 1 and R 6 are represented by the formula: and R 2 is represented by the formula: wherein R 7 is independently hydrogen or methyl and x and y are independently 0 to 100. In the most preferred polymers, R 1 and R 6 are independently m-phenylene, p- phenylene or 2,6-naphthalene; R 2 is independently m-phenylene, p-phenylene, naphthalene, diphenylene-isopropylidene, sulfonyldiphenylene, carbonyldiphenylene, oxydiphenylene or 9,9-fluorenediphenylene; R 5 is hydrogen; R 7 is independently hydrogen or methyl. Generally, the hydroxy-functional polyesters can be prepared by reacting dicarboxylic acids and diglycidyl ethers or diglycidyl esters at conditions sufficient to yield hydroxy ester ether or hydroxy ester linkages. These polyesters are described in, U.S. Patent 5,171 ,820 and copending U.S. Patent Application Serial No. (C-42235) filed October 22, 1996. Polyalkylene oxides which can be used in the practice of the present invention include those polymers comprising polymerized EO units with an average molecular weight of from 100 to 8,000,000, preferably from 400 to 1 ,000,000 and most preferably from 1 ,000 to 100,000. Preferred polyalkylene oxides are poly(ethylene oxide), poly(propylene oxide) poly(ethylene-co-propylene oxide), poly(butyiene oxide) and poly(tetrahydrofuran). The most preferred polyalkylene oxide is poly(ethylene oxide). The polyester polyols which can be used in the practice of the present invention include those prepared by reacting terephthalic acid, isophthalic acid, phthalic anhydride or adipic acid with ethylene glycol. Most preferred is the polyester polyol prepared from adipic acid and ethylene glycol. The aliphatic polyesters which can be used in the practice of the present invention include polymers having the following repeat units: or wherein R 8 and R 9 are independently an alkylene moiety such as ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, methylmethylene, methylethylene, 1-methylpropylene, 2-methylpropylene, 2,2-dimethylpropylene, ethylmethylene, or ethylethylene; R 10 is an arylene moiety such as 1 ,4-phenylene, 1 ,3-phenylene, 1 ,2-phenyiene, 4,4-biphenylene or 2,6-naphthalene; and x = 0 to 0.99. Preferred aliphatic polyesters are polycaprolactone, poly(lactic acid), poly(hydroxybutyrate), poly(hydroxybutyrate valerate), poly(butylene succinate) and poly(butylene adipate). The hydroxy-functional polyesters are blended with the polyalkylene oxides, polyester polyol or aliphatic polyester by conventional dry blending methods using conventional means such as a barrel mixer, or a tumble mixer or by melt blending in an appropriate apparatus, such as a Banbury type internal mixer, rubber mill, single or twin screw extruder or compounder. The amount of the polyalkylene oxide, polyester polyol or aliphatic polyester most advantageously blended with the hydroxy-functionalized polyether is dependent on a variety of factors including the specific polymers used in making the blends, as well as the desired properties of the products resulting from the blends. Typical amounts can range from 1 to 95 weight percent of the blend. Preferably, the polyalkylene oxide, polyester polyol or aliphatic polyester is used in an amount of from 5 to 70 weight percent, more preferably from 10 to 50 weight percent and, most preferably, from 15 to 30 weight percent of the blend. The following examples are for illustrative purposes only and are not intended to limit the scope of this invention. Unless otherwise indicated, all parts and percentages are by weight. Examples 1-6 A poly(hydroxy ester ether) (PHEE) was synthesized by allowing adipic acid to polymerize with bisphenol A-diglycidyl ether according to the method described in U.S. Patent 5,171 ,820. In Example 1 , a blend of the PHEE (45 g) and polyethylene oxide) (PEO, 5 g, MW = 4500) was prepared by mixing the two materials for 15 minutes in a Haake bowl mixer maintained at 120°C to 130°C and with a blade speed of 30 rpm. Other blends (Examples 2-6) of PHEE with PEO having MW = 4500 or 8000 were prepared identically and their compositions are listed in Table I with components expressed as weight percent. The blends were compression molded between sheets made of tetrafluoroethylene fluorocarbon polymers in a 5 by 9 by 0.35 cm mold cavity at a temperature of 80°C and pressure of 100 psi, and the resulting plaques were cut into standard tensile specimens and their mechanical properties determined. The results are shown in Table II. Comparative Example A Unblended PHEE was molded and tested as in Examples 1-6. The test results are shown in Table II (Example A). Moldings of the blends in Examples 1-6 and Comparative Example A were immersed in water at 25°C for 350 hours, and water uptake into the samples was determined as percent weight gain (Table II). In addition, films of the blends were cast from solutions in tetrahydrofuran onto glass plates. Contact angles of water droplets placed on the films were measured and are listed in Table II. Increasing wettability of the films are as indicated by decreasing contact angle. Mechanical properties, water uptake and water contact angle of PHEE were determined using the following test procedures: TEST PROCEDURES Water Uptake The resin was pressed into a 1/8 inch (thickness) by 1 inch (diameter) circular disk mold at 80°C. The circular disk resin was cooled down to room temperature and released from the mold and then vacuum dried overnight at 25 °C. The vacuum-dried resin disk was weighed and the weight (W1 ) recorded. The disk was then placed into a 2 ounce glass bottle filled with 0.3 weight percent of sodium azide in deionized water solution. After 2 weeks immersion in the aqueous solution, the disk was weighed and the weight (W2) recorded. The water uptake was calculated as the percentage of weight gain over the initial dry weight. Water uptake (%) = 100 x (W2 - W1)/(W1 ) Break Stress: ASTM D3039 Elongation: ASTM D3039 Modulus: ASTM D3039 Contact Anαle: ASTM 971 TABLE I Example PHEE (%) PEO PEO (MW = 4500. (MW = 8000. %) 1 90 10 0 2 80 20 0 3 70 30 0 4 90 0 10 5 80 0 20 6 70 0 30 A 100 0 0 TABLE II txampie DreaK Modulus Water Contact Stress (psh Uptake (%) Anαle (%) 1 900 363 298 15 81 2 29 778 103 28 3 946 31 55,633 37 20 4 738 333 626 14 69 5 13 1215 103 33 72 6 1661 4 75,429 34 A 2900 25 402,000 3 90 The dramatic decrease in break stress and modulus in blends of PHEE and PEO, compared with those of PHEE alone, as shown in the above Table II, indicated that PEO can plasticize PHEE owing to the surprising miscibility or partial miscibility of poly(alkylene oxides) in poly(hydroxy ester ethers). Also, incorporation of PEO in PHEE lead to substantially increased moisture sensitivity in the blends compared with unmodified PHEE, reflected by high water uptake (14 to 37 percent) and low water contact angles (20 to 81 percent) of Examples 1-6. Alone, PHEE absorbed only about 3 percent moisture and cast films had a high water contact angle of 90 percent. The ability of poly(alkylene oxides) to plasticize biodegradable poly(hydroxy ester ethers) and the capability of PEO to increase the moisture sensitivity of the polymers indicate that PHEE/poly(alkylene oxide) blends are useful for hot- melt adhesives intended to disintegrate in water and biodegrade during post-consumer disposal. Example 7 Binary mixtures of the poly(hydroxy ester ether) derived from bisphenol A diglycidyl ether and 1 ,4-cyclohexanedicarboxylic acid and poiycaprolactone, poly(lactic acid) or a commercial blend of poiycaprolactone and starch (Bioplast, produced by Biotec Naturverpackungen GmbH) were prepared by mixing in the melt state in a Brabender roller mixer. First, the blend of desired amounts of two polymers was quickly fed into the mixing bowl of the mixer that was preheated to the desired temperature (180°C for blends with poiycaprolactone; 200°C for blends with poly(lactic acid); and 160°C for the blends with the commercial Bioplast resin). During this feeding step, the mixing blades were set at a low speed, but after the chamber was completely full, the lid was closed and the speed increased. Upon addition of the charge, the temperature of the chamber initially decreased by 10°C to 20°C, but it regained its original level in 4 to 5 minutes. The melt-blended mixtures were then compression molded between tetrafluoroethylene-coated plates to form films or rectangular bars for tensile and dynamic mechanical testing. All of the blend samples were also conditioned in the constant temperature room (50 percent relative humidity and 23°C) for at least 24 hours before they were tested. The results of the tests are shown in Tables 111 and IV. Table III Tensile properties of a binary blend of the poly(hydroxy ester ether) derived from bisphenol A diglycidyl ether and 1 ,4-cyclohexanedicarboxylic acid with poiycaprolactone measured on compression molded test specimens. Table IV Tensile properties of a binary blend of the poly(hydroxy ester ether) derived from bisphenol A diglycidyl ether and 1 ,4-cyclohexanedicarboxylic acid with a blend of poiycaprolactone and starch measured on compression molded test specimens.

Claims: CLAIMS: 1. A composition comprising a blend of a hydroxy-functionalized polyester and a polyalkylene oxide, a polyester polyol or an aliphatic polyester. 2. The composition of Claim 1 wherein the hydroxy-functionalized polyester is a poly(hydroxy ester) or a poly(hydroxy ester ether) having repeating units represented by the formula: wherein R 1 is a divalent organic moiety which is primarily hydrocarbon; R 3 is: and R 4 is: wherein R 2 and R 6 are independently divalent organic moieties which are primarily hydrocarbon; R 5 is hydrogen or alkyl and n is from 0 to 100. 3. The composition of Claim 2 wherein R 1 is independently alkylene, cycloalkylene, alkylenearylene, alkyleneoxyalkylene, poly(alkyleneoxyalkylene), alkylenethioalkylene, alkylenesulfonylalkylene, optionally substituted with at least one hydroxy group; arylene, dialkylenearylene, diaryleneketone, diarylenesulfone, diarylene oxide, alkylidene-diaryiene, diarylene sulfide, or a combination of these moieties. 4. The composition of Claim 2 wherein R 1 is independently methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1 ,4-cyclohexylene, 1 ,3-cyclohexylene or 1 ,2-cyclohexylene, optionally substituted with at least one hydroxyl group. 5. The composition of Claim 2 wherein R 1 is represented by the formula: wherein R 7 is independently hydrogen or methyl and x and y are independently 0 to 100. 6. The composition of Claim 2 wherein R 1 is independently m-phenylene, p- phenylene or 2,6-naphthalene. 7. The composition of Claim 2 wherein R 2 is independently alkylene, cycloalkylene, alkylenearylene, alkyleneoxyalkylene, poly(alkyleneoxyalkylene), alkylenethioalkylene, alkylenesulfonylalkylene, optionally substituted with at least one hydroxy group; arylene, dialkylenearylene, diaryleneketone, diarylenesulfone, diarylene oxide, alkylidene-diaryiene, diarylene sulfide, or a combination of these moieties. 8. The composition of Claim 2 wherein R 2 is independently ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1 ,4-cyclohexylene, 1 ,3-cyclohexylene or 1,2-cyclohexylene, optionally substituted with at least one hydroxyl group. 9. The composition of Claim 2 wherein R 2 is represented by the formula: wherein R 7 is independently hydrogen or methyl and x and y are independently 0 to 100 and n is O. 10. The composition of Claim 2 wherein R 2 is m-phenylene, p-phenyiene, naphthalene, diphenylene-isopropylidene, sulfonyldiphenylene, carbonyldiphenylene, oxydiphenylene or 9,9-fluorenediphenylene. 11. The composition of Claim 2 wherein R δ is independently alkylene, cycloalkylene, alkylenearylene, alkyleneoxyalkylene, poly(alkyleneoxyalkylene), alkylenethioalkylene, alkylenesulfonylalkylene, optionally substituted with at least one hydroxy group; arylene, dialkylenearylene, diaryleneketone, diarylenesulfone, diarylene oxide, alkylidene-diaryiene, diarylene sulfide, or a combination of these moieties. 12. The composition of Claim 2 wherein R 6 is independently ethylene, propylene, butylene, pentamethylene, hexamethylene, heptamethyiene, octamethylene, nonamethylene, decamethylene, dodecamethylene, 1 ,4-cyclohexylene, 1 ,3-cyclohexylene or 1 ,2-cyclohexylene, optionally substituted with at least one hydroxyl group. 13. The composition of Claim 2 wherein R 6 is represented by the formula: wherein R 7 is independently hydrogen or methyl and x and y are independently 0 to 100. 14. The composition of Claim 2 wherein the hydroxy-functionalized polyester is a poly(hydroxy ester ether) in which R 1 is butylene, R 2 is diphenylene-isopropylidene, R 5 is H, and n is O. 15. The composition of Claim 1 wherein the polyalkylene oxide is poly(ethylene oxide). 16. The composition of Claim 1 wherein the polyalkylene oxide is polypropylene oxide). 17. The composition of Claim 1 wherein the polyalkylene oxide is poly(ethylene-co-propylene oxide) . 18. The composition of Claim 1 wherein the polyester polyol is formed by the reaction of terephthalic acid, isophthalic acid, phthalic anhydride or adipic acid and ethylene glycol. 19. The composition of Claim 1 wherein the aliphatic polyester is represented by the formulae: or wherein R 8 and R 9 are independently an alkylene moiety, R 10 is an arylene moiety and x = 0 to 0.99. 20. The composition of Claim 1 wherein the aliphatic polyester is poiycaprolactone, poly(lactic acid), poly(hydroxybutyrate), poly(hydroxybutyrate valerate), poly(butylene succinate) or poly(butylene adipate). 21. The composition of Claim 1 wherein the hydroxy-functionalized polyester is present in an amount of from 5 to 99 weight percent, based on the weight of the blend. 22. The composition of Claim 1 prepared by mixing a poly(hydroxy ester) or a poly(hydroxy ester ether) and a polyalkylene oxide, a polyester polyol or an aliphatic polyester in a molten state. 23. A hot-melt adhesive comprising the composition of Claim 1. 24. An adhesive tackifier comprising the composition of Claim 1. 25. A plasticizer comprising the composition of Claim 1. 26. The composition of Claim 1 in the form of a film, a flexible or rigid foam, molded article, fiber, coating or laminate.

Inventors: ANDERSON KENNETH W, MANG MICHAEL N, WANG DAVID S, WHITE JERRY E, ZHAO JIN, ANDERSON, KENNETH, W., MANG, MICHAEL, N., WANG, DAVID, S., WHITE, JERRY, E., ZHAO, JIN
Applicants: ANDERSON KENNETH W, DOW CHEMICAL CO, MANG MICHAEL N, WANG DAVID S, WHITE JERRY E, ZHAO JIN, ANDERSON, KENNETH, W., MANG, MICHAEL, N., THE DOW CHEMICAL COMPANY, WANG, DAVID, S., WHITE, JERRY, E., ZHAO, JIN
Application year: 1997
Main classification: C08L67
IPC codes: C08G63, C08L67, C09J167