Organo-titanate catalysts for preparing pure macrocyclic oligoesters Number:6,787,632 from the United States Patent and Trademark Office (PTO) owispatent Organo-titanate catalysts are prepared that are useful to catalyze depolymerization of a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.<H oligoesters, macrocyclic, Organo, titanate, 6787632.html, Patent, pto, 6787632

Title: Organo-titanate catalysts for preparing pure macrocyclic oligoesters

Abstract: Organo-titanate catalysts are prepared that are useful to catalyze depolymerization of a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

Patent Number: 6,787,632 Issued on 09/07/2004 to Phelps, et al.

Inventors: Phelps; Peter D. (Schenectady, NY), Thompson; Timothy A. (Clifton Park, NY), Wang; Yi-Feng (Waterford, NY), Le Grand; Donald G. (Burnt Hills, NY)
Assignee: Cyclics Corporation (Schenectady, NY)

Appl. No.: 09/974,722

Filed: October 9, 2001

Current U.S. Class: 528/480 ; 528/271; 528/272; 528/279; 528/481

Field of Search: 528/271,272,279,480,481

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Primary Examiner: Boykin; Terressa
Attorney, Agent or Firm: Testa, Hurwitz & Thibeault, LLP

Claims

What is claimed is:

1. A mixture of reaction products of

the mixture being substantially free from di-functional diols other than HO--R.sup.2 --OH,

wherein each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group; R.sup.2 is a C.sub.2 -C.sub.6 alkylene group; each of R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group except that at least one of R.sup.3 and R.sup.4 is a C.sub.1 -C.sub.4 alkyl group, and at least one of R.sup.5 and R.sup.6 is a C.sub.1 -C.sub.4 alkyl group; W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, or a C .sub.1 -C.sub.4 alkylene group; each of x and y is greater than 0; and y>z.

2. The mixture of claim 1 wherein y=2x-z and each of x, y, z is a number greater than 0.

3. The mixture of claim 1 wherein z=0 and y/x>2.

4. The mixture of claim 1 where W is a C.sub.1 -C.sub.4 alkylene group.

5. The mixture of claim 4 wherein R.sup.1 is an isopropyl group; R.sup.2 is a butylene group; each of R.sup.3, R.sup.4, and R.sup.5 is a methyl group; and R.sup.6 is a hydrogen atom.

6. The mixture of claim 1 wherein the mixture of reaction products is substantially free from all mono- and di-functional alcohols.

7. A mixture of reaction products of

n(Ti--(OR.sup.1).sub.4)+(2n-m)((HO--R.sup.2 --OH)+m((HO) --C(R.sup.3)(R.sup.4)--W--C(R.sup.5)(R.sup.6)--(OH)),

the mixture being substantially free from di-functional dials, wherein each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group; R.sup.2 is a C.sub.2 -C.sub.6 alkylene group; each of R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group except that at least one of R.sup.3 and R.sup.4 is a C.sub.1 -C.sub.4 alkyl group, and at least one of R.sup.5 and R.sup.6 is a C.sub.1 -C.sub.4 alkyl group; W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, or a C.sub.1 -C.sub.4 alkylene group; and each of m and n is greater than 0.

8. The mixture of claim 7 where W is a C.sub.1 -C.sub.4 alkylene group.

9. The mixture of claim 7 wherein R.sup.1 is an isopropyl group.

10. The mixture of claim 7 wherein R.sup.2 is a butylene group.

11. The mixture of claim 7 wherein R.sup.1 is an isopropyl group; R.sup.2 is a butylene group; each of R.sup.3,R.sup.4, and R.sup.5 is a methyl group; R.sup.6 is a hydrogen atom; and W is a methylene group.

12. The mixture of claim 7 wherein m/2n is between about 0.1 to about 0.5.

13. The mixture of claim 12 wherein m/2n is between about 0.15 to about 0.25.

14. The mixture of claim 7 further comprising an organic solvent.

15. The mixture of claim 7 wherein the mixture is obtained from a reaction conducted in an organic solvent.

16. The mixture of claim 15 wherein the organic solvent is a chlorohydrocarbon.

17. The mixture of claim 16 wherein the organic solvent is o-dichlorobenzene.

18. The mixture of claim 7 wherein the mixture of reaction products is substantially free from all mono- and di-functional alcohols.

19. A method for depolymerizing a polyester comprising the step of contacting, in the presence of heat, a mixture comprising: a polyester, an organic solvent which is substantially free of oxygen and water, and the mixture of claim 1, to produce macrocyclic oligoesters free from macrocyclic co-oligoesters.

20. The method of claim 19 wherein the polyester comprise poly(1,4-butylene terephthalate).

21. A method for depolymerizing a polyester comprising the step of contacting, in the presence of heat, a mixture comprising: a polyester, an organic solvent which is substantially free of oxygen and water, and the mixture of claim 7, to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

22. A method for depolymerizing a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters, the method comprising the step of contacting, in the presence of heat, a mixture comprising: a polyester, an organic solvent which is substantially free of oxygen and water, and a mixture of reaction products of:

wherein each R.sup.1 is independently a C.sub.1 -C,.sub.10 alkyl group; R.sup.2 is an unbranched C.sub.2 -C.sub.6 alkylene group; and each of m and n is greater than 0, and m/n>2.

23. The mixture of claim 1 wherein W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, an ethylene group, a propylene group, or a butylene group.

24. A method for depolymerizing a polyester comprising the step of contacting, in the presence of heat, a polyester, an organic solvent, and a mixture of reaction products of

wherein each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group; R.sup.2 is a C.sub.2 -C.sub.6 alkylene group; each of R.sup.3, R.sup.4, R.sup.5 and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group; W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, or a C.sub.1 -C.sub.4 alkylene group; each of x and y is greater than 0; and y>z.

25. The method of claim 24 wherein the mixture of reaction products is substantially free from di-functional diols other than HO--R.sup.2 --OH.

26. A method for depolymerizing a polyester comprising the step of contacting, in the presence of heat, a polyester, an organic solvent, and a mixture of reaction products of

wherein each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group; R.sup.2 is a C.sub.2 -C.sub.6 alkylene group; and each of m and n is greater than 0, and m/n>2.

27. The method of claim 26 wherein R.sup.1 is an isopropyl group.

28. The method of claim 26 wherein R.sup.2 is a butylene group.

29. The method of claim 26 wherein R.sup.1 is an isopropyl group and R.sup.2 is a butylene group.

30. The method of claim 26 wherein 5>m/n>3.

31. The method of claim 26 wherein the mixture is obtained from a reaction conducted without a solvent.

32. The method of claim 26 substantially free of all mono- and di-functional alcohols.

33. The method of claim 26 wherein R.sup.2 is an unbranched C.sub.2 -C.sub.6 alkylene group.

Description

TECHNICAL FIELD

This invention generally relates to catalysts. More particularly, the invention relates to organo-titanate catalysts useful for preparing macrocyclic oligoesters.

BACKGROUND INFORMATION

Linear polyesters such as poly(alkylene terephthalate) are generally known and commercially available where the alkylene typically has 2 to 8 carbon atoms. Linear polyesters have many valuable characteristics including strength, toughness, high gloss, and solvent resistance. Linear polyesters are conventionally prepared by the reaction of a diol with a dicarboxylic acid or its functional derivative, typically a diacid halide or ester. Linear polyesters may be fabricated into articles of manufacture by a number of techniques including extrusion, compression molding, and injection molding.

Recently, macrocyclic oligoesters were developed which are precursors to linear polyesters. Macrocyclic oligoesters exhibit low melt viscosity, which can be advantageous in some applications. Furthermore, certain macrocyclic oligoesters melt and polymerize at temperatures well below the melting point of the resulting polymer. Upon melting and in the presence of an appropriate catalyst, polymerization and crystallization can occur virtually isothermally.

One method for synthesis of the macrocyclic oligoesters includes the step of contacting a diol of the formula HO--A--OH with a diacid chloride of the formula: ##STR1##

where A is an alkylene, or a cycloalkylene or a mono- or polyoxyalkylene group; and B is a divalent aromatic or alicyclic group. The reaction typically is conducted in the presence of at least one amine that has substantially no steric hindrance around the basic nitrogen atom. An illustrative example of such amines is 1,4-diazabicyclo[2.2.2]octane (DABCO). The reaction usually is conducted under substantially anhydrous conditions in a substantially water immiscible organic solvent such as methylene chloride. The temperature of the reaction typically is between about -25.degree. C. and about 25.degree. C. See, e.g., U.S. Pat. No. 5,039,783 to Brunelle et al.

Macrocyclic oligoesters may also be prepared via the condensation of a diacid chloride with at least one bis(hydroxyalkyl) ester such as bis(4-hydroxybutyl) terephthalate in the presence of a highly unhindered amine or a mixture thereof with at least one other tertiary amine such as triethylamine, in a substantially inert organic solvent such as methylene chloride, chlorobenzene, or a mixture thereof. See, e.g., U.S. Pat. No. 5,231,161 to Brunelle et al.

Another method for preparing macrocyclic oligoesters is to depolymerize linear polyester polymers in the presence of an organotin or titanate compound. In this method, linear polyesters are converted to macrocyclic oligoesters by heating a mixture of a linear polyester, an organic solvent, and a trans-esterification catalyst such as a tin or titanium compound. The solvents used, such as o-xylene and o-dichlorobenzene, usually are substantially free of oxygen and water. See, e.g., U.S. Pat. Nos. 5,407,984 to Brunelle et al. and 5,668,186 to Brunelle et al.

To be useful for the preparation of macrocyclic oligoesters, the organo-titanate catalyst should be soluble in the solvent of the depolymerization reaction, should be in a physical state that allows it to be readily added to the reaction, and should be an active catalyst capable of establishing the desired equilibrium in a reasonable time. Catalysts prepared from tetraisopropyl titanate and two equivalents of butanediol, for example, tend to polymerize and gel from solution. To circumvent this gelation, diethylene glycol was used to substitute part of the butanediol. One technique for preparation of organo-titanate catalysts uses butanediol together with diethylene glycol. See, U.S. Pat. No. 5,710,086 to Brunelle et al. Catalysts prepared according to this method contain moieties of diethylene glycol, which are later incorporated into the macrocyclic oligoesters prepared using the catalysts. The incorporation of diethylene glycol moieties causes deleterious effects on the mechanical properties (e.g., modulus) and thermal properties (e.g., melting point and heat distortion temperature) of the polyester prepared from the macrocyclic oligoesters.

Unfortunately, it is desirable for certain applications such as automotive paint oven or rapid molding and cycle time to employ pure macrocyclic oligoesters, i.e., macrocyclic oligoesters substantially free from macrocyclic co-oligoesters. To conduct molding at high speed, the material (e.g., polybutylene terephthalate polymerized from macrocyclic oligoesters) that is molded needs to crystallize rapidly. High purity is thus required. Also, in making a part by automotive paint oven, the part is less likely to deflect if the material (e.g., polybutylene terephthalate polymerized from macrocyclic oligoesters) has a high heat distortion temperature. In addition, higher crystallinity generally leads to higher modulus and better creep resistance. Furthermore, employing pure macrocyclic oligoesters (e.g., macrocyclic butylene oligoesters) simplifies the manufacturing and product-recovering process as there is no contamination with other diols (e.g., diols derived from diethylene glycol). Methods that lead to pure macrocyclic oligoesters are thus desired.

SUMMARY OF THE INVENTION

It has been discovered that organo-titanate catalysts of the invention are useful for preparing macrocyclic oligoesters that are substantially free from macrocyclic co-oligoesters. Further, the organo-titanate catalysts of the invention may be used to prepare macrocyclic co-oligoesters.

In one aspect, the invention is directed to a mixture of reaction products of

The mixture is substantially free from di-functional diols other than HO--R.sup.2 --OH. Each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group. R.sup.2 is a C.sub.2 -C.sub.6 alkylene group. Each of R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group except that at least one on R.sup.3 and R.sup.4 is a C.sub.1 -C.sub.4 alkyl group and at least one of R.sup.5 and R.sup.6 is a C.sub.1 -C.sub.4 alkyl group. W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, or a C.sub.1 -C.sub.4 alkylene group. Each of x and y is greater than 0. In addition, y is larger than z.

In another aspect, the invention is directed to a mixture of reaction products of

The mixture is substantially free from di-functional diols. Each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group. R.sup.2 is a C.sub.2 -C.sub.6 alkylene group. Each of R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group except that at least one of R.sup.3 and R.sup.4 is a C.sub.1 -C.sub.4 alkyl group and at least one of R.sup.5 and R.sup.6 is a C.sub.1 -C.sub.4 alkyl group. W is an oxygen atom, a sulfur atom, a nitrogen-containing group, a phosphorus-containing group, or a C.sub.1 -C.sub.4 alkylene group. Each of m and n is greater than 0.

In yet another aspect, the invention is directed to a mixture of reaction products of

Each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group. R.sup.2 is a C.sub.2 -C.sub.6 alkylene group. Each of m and n is greater than 0. The ratio of m to n is greater than 2.

In yet another aspect, the invention is directed to a method for depolymerizing a polyester. The method includes providing one or more of above-described mixtures of reaction products; contacting, in the presence of heat, a mixture including: a polyester, an organic solvent which is substantially free of oxygen and water, and one of the above-described mixtures, to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and claims.

DESCRIPTION

According to the present invention, organo-titanate catalysts are prepared that are useful for catalyzing depolymerization of polyesters to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

Definitions

The following general definitions may be helpful in understanding the various terms and expressions used in this specification.

As used herein, a "macrocyclic" molecule means a cyclic molecule having at least one ring within its molecular structure that contains 8 or more atoms covalently connected to form the ring.

As used herein, an "oligomer" means a molecule that contains 2 or more identifiable structural repeat units of the same or different formula.

As used herein, an "oligoester" means a molecule that contains 2 or more identifiable ester functional repeat units of the same or different formula.

As used herein, a "macrocyclic oligoester" means a macrocyclic oligomer containing 2 or more identifiable ester functional repeat units of the same or different formula. A macrocyclic oligoester typically refers to multiple molecules of one specific formula having varying ring sizes. However, a macrocyclic oligoester may also include multiple molecules of different formulae having varying numbers of the same or different structural repeat units. A macrocyclic oligoester may be a co-oligoester or multi-oligoester, i.e., an oligoester having two or more different structural repeat units having an ester functionality within one cyclic molecule.

As used herein, "an alkylene group" means --C.sub.n H.sub.2n --, where n.gtoreq.1.

As used herein, "a cycloalkylene group" means a cyclic alkylene group, --C.sub.n H.sub.2n-x-, where x represents the number of H's replaced by cyclization(s).

As used herein, "a mono- or polyoxyalkylene group" means [--(CH.sub.2).sub.m --O--].sub.n --(CH.sub.2).sub.m --, wherein m is an integer greater than 1 and n is an integer greater than 0.

As used herein, a "mixture of reaction products" means a mixture of compounds resulting from a chemical reaction. Thus, a "mixture of reaction products" may refer to a mixture of compounds resulting from a chemical reaction that includes one or more solvents and/or any side products (e.g., a mono- or di-functional alcohol). A "mixture of reaction products" may also refer to a mixture of compounds resulting from a chemical reaction and after removal or separation of one or more solvents or one or more side products, or with the addition of one or more solvents or additives.

Macrocyclic oligoesters that may be prepared using the catalysts of this invention include, but are not limited to, poly(alkylene dicarboxylate) macrocyclic oligoesters having a structural repeat unit of the formula: ##STR2##

where A is an alkylene, or a cycloalkylene or a mono- or polyoxyalkylene group; and B is a divalent aromatic or alicyclic group.

Illustrative examples of macrocyclic oligoesters include macrocyclic oligoesters of poly(1,4-butylene terephthalate), poly(1,3-propylene terephthalate), poly(1,4-cyclohexylenedimethylene terephthalate), poly(ethylene terephthalate), and poly(1,2-ethylene 2,6-naphthalenedicarboxylate).

In one aspect, the invention is directed to a mixture of reaction products of

The mixture of reaction products is substantially free from di-functional diols other than HO--R.sup.2 --OH. That is, the mixture is substantially free from (HO)--C(R.sup.3)(R.sup.4)--W--C(R.sup.5)(R.sup.6)--(OH). "Substantially free" in this context means that the mixture of reaction products is at least 90%, and preferably 95%, free of all di-functional diols other than HO--R.sup.2 --OH, which is determined by the amount of diols originally present.

Referring to the above formula, each R.sup.1 is independently a C.sub.1 -C.sub.10 alkyl group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, or a hexyl group. R.sup.2 is a C.sub.2 -C.sub.6 alkylene group, such as an ethylene group, a propylene group, or a butylene group. Each of R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group. However, at least one of R.sup.3 and R.sup.4 and at least one of R.sup.5 and R.sup.6 is a C.sub.1 -C.sub.4 alkyl group. Thus, (HO)--C(R.sup.3)(R.sup.4)--W--C(R.sup.5)(R.sup.6)--(OH) is a secondary or a tertiary alcohol. W is an oxygen atom, a sulfur atom, a nitrogen-containing group (e.g., a --N(R.sup.7)-- group, wherein R.sup.7 is a hydrogen atom or a C.sub.1 -C.sub.8 alkyl group), a phosphorus-containing group (e.g., a --P(R.sup.8)-- group, wherein R.sup.8 is a hydrogen atom or a C.sub.1 -C.sub.8 alkyl group), or preferably a C.sub.1 -C.sub.4 alkylene group such as a methylene group, an ethylene group, a propylene group, or a butylene group. Each of x and y is greater than 0, and y is greater than z. Thus, there is more HO--R.sup.2 --OH than (HO)--C(R.sup.3)(R.sup.4)--W--C(R.sup.5)(R.sup.6)--(OH).

The reaction of the titanate and the diol(s) may be conducted in an organic solvent or neat. Any organic solvent may be used as long as it does not interfere with the desired reaction and the properties of the mixture of reaction products. Illustrative organic solvents that may be used include, but are not limited to, chlorohydrocarbons such as chloroaromatic hydrocarbons (e.g., o-dichlorobenzene). Preferably, no proton donating compounds such as water or acids are present during the reaction.

In one embodiment, the mixture of reaction products is prepared via a metathesis reaction. The reaction may be conducted at any temperature and pressure as long as it yields the desired mixture of reaction products. For example, the reaction may be carried out at a temperature at about 25.degree. C. to about 190.degree. C. In one embodiment, the reaction of the titanate and the diol(s) is conducted at about 120.degree. C. to about 180.degree. C. In another embodiment, the reaction of the titanate an