MXPA97002206A - Copolieste - Google Patents

Abstract

The present invention relates to a hydroxycarboxylic acid copolyester of R-stereospecific configuration containing a majority of first repeating units capable of forming a highly crystalline high melting point homopolyester and a minority of second repeating units, when they are randomly copolycondensed. the first repeating units, capable of reducing the melting point of said homopolyester and characterized by one or more of: higher crystalline melting point, shorter crystallization time, impact resistance grooved at the age of one month, in comparison with the corresponding random polyester, and said majority of repeating units in the polyester chain being present in blocks longer than that corresponds to its overall molar proportionality, the copolyester can be made by fermentation, controlling the distribution of repeating units by reference to the employer of feeding substrates corresponding to the respective repetition units

Description

COPOLYTHERIES DESCRIPTIVE HEALTH This invention relates to copolyesters and in particular to those having repeating hydroxid units. The hydroxy acids p > The condensed ones, especially those of R-stereospecific configuration made rcrocrobiologically, have recently been commercially available. Of these, the homopolymer of polyhydric acid (PH) is capable of a high level of stability, but melts at a relatively high temperature of 174-180 ° C / a. molecular weight is relatively fast. Copolymers (PHKV) that contain 3-h? Units roxivalerate, for example, at 3-30 mole percent melt at a lower temperature and are correspondingly more stable during the melt process, but crystallize more slowly. It has been found that the crystallization behavior can be influenced by joining the repeating units in a special configuration. In accordance with the invention, a copolyether of hydroxy carboxylic acid of the R-stereo-specific configuration contains a majority of first repeating units capable of forming a highly crystalline high melting homopolyester and a minority of second repeating units capable of lowering the melting point of said polyester furnace when they are randomly copolycondensated with said first repeating units: characterized by one or more of the following characteristics: a) a crystalline melting point greater than at least 1.0, especially at least 15 ° C which that of the corresponding random copolyester; b) a mean crystallization time at 70 ° C or 120 ° C of less than 0.9, especially less than 0.5, of that of the corresponding random copolyester; c) slotted impact force of 1 m IZOD at the age of at least one month equal to that of the corresponding random copolyester of molecular weight greater than 20%; d) said majority of repeating units in the polyester chain present in blocks longer than corresponds to their total molar proportionality. The repeating units in the copolyesters preferably include the residues of 3-hydroxybutyric acid (HB) and other hydroxy acids, especially 4-hydroxybutyric acid (4HB) or 3-hydroxyvaleric acid (HV). Preferably the HB units are in a majority, especially at least 70, especially at least 80, for example 70-98 mole percent of the total units. If desired, the minority units may be of more than one chemical formula. Polyesters containing HB and HV units are referred to herein as "PHBV". The molecular weight of the polyesters is typically in the range of 100000 to 2000000, conveniently 150000 to 1000000. It seems that the acceptable mechanical properties are obtained at lower molecular weights than what has been necessary when using random copolyesters of a similar total chemical composition. The invention also provides methods for making them copolymers particularly by fermentation, characterized in controlling the distribution of the repeating units by reference to the pattern of the feed substrates corresponding to the respective repeating units. In a process as such, the following procedures are used: preferably intermittent feeding operation; alternate the introduction of the substrates corresponding to the respective repeating units. Generally, a predetermined fraction of the desired consumption of each substrate is fed over a period and then maintained until its concentration in the. means is approximately zero; that is, it has dropped to a level between 1% of its maximum feed concentration and the. level at which the body has begun to consume its polyester stock. The point of change may be the same or different for the respective foods. The first food fed can be the majority of the food of the minority of the food. The really fed materials can be chemically 100% of a food or can be a mixture of chemical compounds that produce the same unit of repetition, or they can be a mixture of which preponderantly produces a repetition unit but with a small proportion, for example, 0.01 to 1.0% of molecular weight that produces another. The feeding times of each food, for example, can be in the range of 0.5 to 20 hours, depending on how large it is required to move away from the random character. preferably a polyester folding stage wherein an essential nutrient for cell growth is limited; the limiting nutrient is preferably phosphorus, instead of nitrogen but is fed at a concentration that allows a moderate cell growth during polyester abatement; preferably nitrogen is present in soluble medium; this also seems to provide for moderate cell growth. The microorganism used in the fermentation may be able to knock down a crystallizable copolyester. When the copolyester is PHBV with PHB in the molar majority, the organism is suitably a bacterium of the genus ñlcaligenes, fíthiorhodium, fízotobacter, Bacillus, Nocardia, Pseudo onas, Rhizobium or Spirillium. The genetic material required may be genetically modified or may have been introduced into a foreign organism such as a eucalyptus. Particularly preferred microorganisms are selected from flcaligenes eutrophus and fllcaligenes latus. Microorganisms that lack metabolic pathways to produce PHB from foods of non-carbon numbers are especially preferred, since they produce purest PHV in the PHV phase of the fermentation: an example is the. ñ. eutrophus NCIHB 40124 modified, described in EP-A-0431883. Foods for making the PHBV copolyesters can be for example: for the HB: hexose units such as glucose, fructose, gluconate; alcohols and carboxylates having a linear even number of carbon atoms, for example ethanol, acetate and n-butyrate; for the HV units: alcohols and carboxylates having a non-linear number of carbon atoms, for example n-propanol and propionate. The copolyester can be recovered from the fermentation biornase by known methods, for example solvent extraction or by culture, i.e. the decomposition of non-copolyester cell material. Said decomposition is described in EP-R-0145233 and more recent patent applications. The polyester product can be in the form of dry solid particles or in an aqueous latex. As a result of the faster crystallization, the polyesters according to the invention can be cultured as dry solids more easily than the corresponding random polyesters, especially those in HV, for example about 12 mole percent. The invention makes it possible to provide polyesters having the same crude chemical composition but a scale of mechanical properties, a greater increase in convenience compared to loading the food to the ferrnentator and maintaining an inventory of different polyesters for mixing. The polyesterers are suitable for use in known set-up procedures and for making articles for which the random PHRs are used or proposed. Because they are capable of relatively fast crystallization, they are especially suitable for melt-setting processes such as extrusion, injection molding and compression molding, wherein an article is formed in its initial form without mechanical treatment to increase the Substantially substantial. They can be used in processes such as fiber spinning, film extrusion and film molding, and also in such processes, including injection blow molding with one or more stretch steps to increase the cps + alinity towards the maximum that is you can get. Its faster cps + alizacion allows shorter cycle times than are now convenient. The polyesters of the invention appear to undergo less secondary crystallization after configuration, unlike what known random polyesters do, and thus are less subject to change in mechanical properties after configuration. The polyesters can be used in the solution processing, using for example chloroform, dichloromethane or 1,2-dichloroethane as a solvent. If they are recovered from the microbiological cells as latex, or converted into latex by enolifying a solution and removing the solvent, they can be used in the majority of latex applications, especially coated or bound products, for example coated or bound paper or cellulose or as a component of paint. In these operations of use, the polyesters can be formulated, appropriately with usual processing additives such as pigments, fillers, fibers and plasticizers.

EXAMPLE 1 The following preparation was carried out three times: An aqueous medium was prepared containing the following, expressed in g per 1, and having a pH of about 7 (controlled by the addition of ammonia): (gS? 4 7H20 2.2 K2 SO * 3.0 N 2S? 4 0.18 FeNH citrate, 0.17 Glucose 60 (corrected error) Stroke (SO4: Cu 4.5 rng, Zn 90 rng, end 40 mg, Ca 360 rng acetate) Phosphoric acid 1.69 (mi of 16M) - A ferrnentator containing 3 liters of the above medium was fertilized with a starting culture of Álcaligenes eutrophus described below. The medium was incubated at 34 ° C for 24 hours until the phosphate content of the medium became 1imitant. Each medium was used to produce PHBV of the food by adding 400 g of carbon (co or C) per g of phosphorus (as P) present. The organisms and food in the three loads were as follows: fl (control): NCIMB 12080 as a variant deposited under reference NCIMB 40529; glucose (80% of total carbon) and propionic acid (20% of total carbon), fed during 48 hours at speeds that give almost maximum production speed; B NCII1B 40124 (see EP-ñ-0431883); glucose (60% of total carbon) initially between 56 g for one hour; then propionic acid (40% of total carbon) 19 g for one hour: then this cycle was repeated per hour at 62 hours, varying the feed rates to give the near maximum production speed: C NCIMB 40124; glucose and propionic acid in the same proportion of global carbon co or B; propionic acid below the toxic limit for 7 hours; glucose for 13 hours; propionic acid below the toxic limit for 13 hours; glucose for 11 hours. In each run, the medium was agitated and sprayed with air at a speed avoiding oxygen limitation and accumulation of unreacted food. The resulting cells were cultured on heating, treated with protease, oxidized with hydrogen peroxide and separated from the polyester by centrifugation. The weight of the dead cell in the loads was: A: 150 g / 1 (70% w / w PHBV); B: 108 g / 1 (62% w / w PHBV); C: 128 g / 1 (62% w / w PHBV). The polyester products were: A: 88 mole percent HB, 12 mole percent HV; (This is a substantially random copolyester); B: 88 molar percent HB, 12 molar percent HV; (The repeating units in this copolyester are believed to be present in short blocks consisting of or preponderant in HB or HV). C: 88 molar percent HB, 12 molar percent HV. (The repeating units in this copolyester are believed to be present in blocks each longer than in B).

METHODS OF TESTING MECHANICAL TESTS Polyester samples were mixed in powder with a phr of boron nitride nucleator material and processed in molten bath in a single-worm Betol extruder through a 5 mm circular die and granulated into small pieces. It is injection molded in test bar. The tension bars had a rnanometric length of 40 mm with typical cross-sectional areas of 2.4 x 5.3 mm and were tested on an Instron 1122 instrument equipped with a NENE data analysis program. A transverse speed of 10 rnrn per minute was used. Izod impact strength was determined using a Zwicl- pendulum apparatus. THERMAL LYSIS: For differential thermal analysis (DSC) a Mettler Tfi 4000 instrument is used under programmed heating control from 20 to 200 ° C per minute to measure the behavior of the molten bath. Tg was measured by this sequence: heating from 20 to 00 ° C at 100 ° C per minute; extinguishing the material at -45 ° C cooling to 100 ° C per minute; reheating the amorphous sample at 100 ° C to 20 ° C per minute. Tg was the point of inflection in the warming trace. Mean times of crystallization were measured by DSC: A sample of 10 ng was melted by heating at 200 ° C to 0 ° C per minute; maintaining at 200 ° C for 2 minutes; rapidly cooling to 100 ° C per minute at a crystallization temperature of 70 ° C (non-nucleated) or 120 ° C (nucleated); it remained isothermally at the temperature for up to one hour and the crystallization isotherm was recorded. The average time became the minimum of the crystallization peak.

TABLE 1 POLYESTER A B C Random blocks Short Long Property (fresh) HV molar percentage 12 12 12 VM '000 435 299 338 Trn ° C 156.8 169.8 172.7 Hrn 3 / g 60.6 45.2 54.7 Te ° C does not crystallize on cooling Crystal t.o.5, rnin at 70 ° C 5.83 4.25 2.5 Crystal to.5, min at 120 ° C 6.27 5.73 2.07 Tg ° C -0.1 -1.6 -0.5 Property (1 month after molding) Young MPa Module 1027 575 1049 Peak Load Effort MPa 29 22.4 29.4 Elongation at break% 11 10.7 11.1 Impact of grooved IZOD of 1 mm 3 / rn 85 113 79 It is evident that: The melting points of B and C are substantially higher than for C and in fact reach that of the PHB homopolyester (179 ° C); The heat of fusion is substantially lower and may indicate a lower total crystallinity, especially for B; Crystallization is faster, especially for C; one month after molding, B is noticeably more flexible than the control; At one is the impact resistance of B is substantially greater than what could be expected in view of its molecular weight less than A.

EXAMPLE 2 The procedure of steps B and C of Example 1 was repeated with the modifications that the substrate ratio was adjusted to produce 7 or 8 mole percent of HV units and the feed times in the long period operations were 12 hours instead of .1.3 hours. The products of these operations (D, E) were molded as described above and tested one month after molding in comparison with a random copolymer F F) and a mixture (G) of a PHB oven with a cop 85 : 15 B: V to give an average V content of 8 mol%. The results are shown in table 2.

TABLE 2 POLYESTER D E F G Blocks Short long Random Mix % Molar HV 7 8 8 8 Molding VM '000 554 371 418 429 Trn ° C 155.5 159.2 148.8 172.9 tees, min at 120 ° C 5.7 3.3 10.0 1.6 Module Young MPa 1160 11.37 1.241 1139 Stress at peak load MPa 31.46 30.18 32.27 30.61 Elongation at break% 14.74 9.37 7.32 8.37 Impact of grooved IZOD of 1 mm 3 / m 86.25 96.25 55.75 62.25 A useful increase in impact resistance of IZOD was achieved, with a clear improvement in elongation at break, compared to random or mixed polyester. NOTE: The microorganisms referred to here by NCIMB numbers have been deposited with National Collections of Industrial and Marine Bacteria Limited (NCIMB), PO Box 31,135 Abbey Road, Aberdeen AB9 8DG, United Kingdom under the terms and conditions of the treaty of Budapest.

Claims (11)

NOVELTY OF THE INVENTION CLAIMS

1. A copolyester of hydroxy carboxylic acid of R-stereospecific configuration containing a majority of first repeating units capable of forming a highly crystalline high-melting homopolyether and a minority of second repeating units, when randomly selected polycondensed with said first repeating units, with capacity to reduce the melting point of said polyester furnace: characterized by one or more of the following characteristics: a) a crystalline melting point greater than at least 10, especially at less 15 ° C than the corresponding random copolyester; b) an average crystallization time of 70 ° C to 120 ° C less than 0.9, especially less than 0.5, than that of the corresponding random polyester; c) resistance to the impact of IZOD of 1 millimeter grooved at an age of 1 month at least equal to that of the corresponding random polyether of 20% higher molecular weight; d) said majority of repeating units in the chain < polyester- present in the blocks greater than that which corresponds to its global molar proportionality.

2. A copolyester according to claim 1, wherein the repeating units in the copolyesters include the residues of 3-hydroxybutyrate (HB) acid and the other hydroxy acids, especially 4-hydroxybutyl acid. rich (4HB) or 3-hydroxyvaleric acid (HV).

3. A copolyester according to claim 2, wherein the HB units are at least 70 mol% of the total units.

4. A process for making a copolyester according to any of the preceding claims by fermentation, characterized by controlling the distribution of repeat units by reference to the pattern of feed substrates corresponding to the respective repeating units.

5. A method according to claim 4 operated on an intermittent feed basis with alternate introduction of substrates corresponding to the respective repeat units, a predetermined fraction of the intended consumption of each substrate being fed for a period and then maintained until its concentration has fallen to a level between 1% of its maximum feed concentration and the level at which organisms have started a net consumption of their polyester stock.

6. A method according to claim 4 or claim 5 which includes a step of polyester folding in which an essential nutrient for the growth of a cell is limited, characterized in that the limiting nutrient is phosphorus but is fed to a concentration that allows a moderate degree of cell growth - that accompanies said polyester shrinkage.

7. A process according to any of claims 4 to 6 in which the fermentation organism lacks netabolic pathways to produce HB units from substrates of non-carbon numbers.

8. A method according to any of claims 4 to 7 wherein the organism of faith is Alcaligenes eutrophus.

9. A method according to any of the preceding claims which includes recovering copolyester from the fermentation biomass by decomposition of cellular material that is not copolyester.

10. A process according to claim 9, in which the copolyester is recovered as dry solid particles.

11. A method for making articles configured by means of a molten bath configuration of a polyether according to claims 1 to 3 or made by a method according to any of claims 4 to 10. 12.- A method according to Claim 11 wherein the article is formed in its final confi rmation without mechanical treatment to increase its crystallinity substantially. 13. A process according to claim 9, in which the copolyester is recovered as a latex. 14. A process for making coated and / or joined products by applying a latex of a copolyester according to any of claims 1 to 3 or made by a process according to any of claims 4 to 9 and 13.