MXPA97001818A - Polyes composition - Google Patents

Abstract

The present invention relates to: A polymer composition consisting of: a) a stereospecific polyester, preferably derived from fermentation, of molecular weight greater than 100000 consisting of repeating units of the formula - O - CmHn - CO - in which n = 2m and units with m = 3 and m = 4 with respectively a side group of C1 and C2 in the carbon atom close to oxygen in the polymer chain copolymerized with each other, m being 3 in 70-95 mole percent of such units; ) at least one alkylphenol, wherein the alkyl group preferably contains at least one tertiary carbon atom adjacent to, or within the carbon atoms of the phenol core, the alkylphenol can be clogged and can contain a C1- alkoxy group 6 in the para position with respect to the phenolic hydroxy group, the suitable alkylphenols include 2-tert-butyl-4-hydroxyanisole and alpha- or delta-tocopherol, and others usable as antioxidants in food, oils and food systems. The polyester and alkylphenol and the relative proportions thereof are chosen to provide for the inhibition of the crystallization of the polyester, which corresponds to an Avrami parameter of less than 0.

Description

POLYESY COMPOSITION FIELD OF THE INVENTION This invention relates to a polyester composition and in particular to a composition comprising an aliphatic polyester and a plasticizer.

BACKGROUND OF THE INVENTION Examples of such polyesters have been made commercially available as the result of the development of microbiological processes to manufacture them. The earliest example, PHB, is difficult to treat in the molten state due to its low thermal stability at its melting temperature. Corresponding copolymers melt at a lower temperature. When such a polyester is used to make articles formed of plastic, it may be necessary to formulate it with a plasticizer to obtain the desired mechanical properties. Many plasticizer compounds have been proposed for this task, but there is doubt about the improvement in the mechanical properties obtained and their permanence. It has now been found that compositions comprising such polyesters (the term herein includes homopolyesters, copolyesters and mixtures thereof) and one or more phenolic compounds of a defined kind show further advantages.

DESCRIPTION OF THE INVENTION According to the invention, in its first aspect, a polymer composition comprises: a) a stereospecific polyester of molecular weight PM over 100,000 consisting of repeated units of formula -0-C? Hn-CO- in which n = 2m, and units with m = 3 and m = 4, with a side group of Ci and C2 respectively in the atom of carbon adjoining the oxygen in the polymer chain, are copolymerized with each other, is 3 in 70-95 mole percent of such units; and (b) at least one alkyl phenol. In alkylphenol, there is preferably at least one alkyl group containing a chain of at least 2 and suitably up to 20 carbon atoms. Preferably, at least one such alkyl group contains at least one tertiary carbon atom, for example attached to 2 different side substituents of hydrogen, at least one of whose atoms is carbon. The chain preferably bears at least 2, and conveniently, up to 6 hydrocarbon side substituents, and these are preferably Ci-β, especially methyl, or the tertiary carbon atom is preferably adjacent to, or within, 4 carbon atoms. of the phenol core. On any of the tertiary carbon atoms, any substituent atom other than carbon is preferably oxygen.

The alkyl phenol is preferably "hindered", that is, the rotation of the alkyl group is inhibited by collision with a nuclear substituent (especially OH or 0-alkyl) in the ortho position to the alkyl group or prevented by a ring-forming union of the alkyl group. alkyl group to the phenolic nucleus. The alkyl phenol preferably also contains at least one hydrocarbonoxy group, preferably in the para position to the phenolic OH group. Conveniently, the hydrocarbonoxy group is C alco-alkoxy & Particular examples of suitable alkylphenols are: 2-tert-butyl-4-hydroxyanisole-3-tert-butyl-4-hydroxyanisole (mixture BHf1). 3,5-di-tert-butyl-4-hydroxytoluene (BHT) α-tocopherol (a ~ T) 6-tocopherol (dT) Instead of the free alkylphenol, it may be an ester thereof, for example a carboxylic ester of Ci-ß -It is believed that such an ether is an example of a precursor that can be decomposed in alkylphenol during treatment and / or aging of polyester. A thermal and / or oxidative reaction product of the alkylphenol, which can originate as such from the treatment and / or aging, can be added instead of the free alkylphenol. A particular example is 2,2'-dihydroxy-5,5'-dimethoxy-3,3'-di-tert-butylbiphenyl, an oxidation product of 3-tert-butyl-4-hydroxyanisole.

The defined class of alkylphenols includes compounds effective as antioxidants, for example in food, oils and polymer systems. These can be used and are believed to be preferable, especially if they are not harmful to living beings and / or are biodegradable. The invention includes: (a) the freshly prepared composition (b) the composition after the treatment steps except conversion to the finished article. (c) the finished article: in which the defined alkylphenol is present and / or any conversion product that has been formed therefrom. The polyester is preferably capable of a high level of crystallinity, for example about 30%, especially 50-90%, in the absence of additives. The MW molecular weight of PHfl is for example up to 2 x 106. In PHfls having m = 3 and m = 4 there may be very small, typically fractional, percentages of units having higher values of. PHfl consisting essentially of m = 3 units is poly-3-R-hydroxybutyrate (PHB), and PHfl consisting of rn = 3 and 4 units is polyhydroxybutyrate-co-valerate (PHBV). PHfl can be a fermentation product, especially a process in which a microorganism releases PHfl during normal growth or is forced to do so in that way by deprivation of one or more cellular nutrients necessary for cell multiplication. The microorganism can be wild or utado or it can have the necessary genetic material introduced in it. Alternatively, the necessary genetic material can be hosted by a eukaryote. The PHfl developed in this way is R-stereospecific. Examples of suitable microbiological processes are described in EP-fl-69497 (fllcaligenes eutrophus). The PHfl can be extracted from the fermentation product cells by decomposing the cellular material different from PHfl leaving microscopic granules of PHfl, or by means of an organic solvent applied to the fermentation product or to such product after one or more steps such as cell lysis or decomposition partial of cellular material. For specialized end uses, the cellular material can be left partially or totally with the PHf1, but preferably it is subjected to cell lysis. Alternatively, the PHfl can be synthetic, produced for example as described by Bloembergen et al. In Macromolecules 1989, 33, 1656-1663 (PHB) and 1663-1669 (PHBV). The polyester component of the composition may contain more than one polyester, for example: (a) polyesters having the same repeating units but different molecular weight; Part of the polyester component can be of too low molecular weight to be usable only as structural material. (b) polyesters having different combinations of repeating units. (c) polyesters of a different class (for example synthetic with microbiological) but mutually miscible. (di polyester of a different kind but not mutually miscible. (e) polyester, whether or not different from (a) to (b) having a different history, for example a different extraction process or manufacturer or different prior treatment such as reprocessing or recirculation or modification of the end group The alkyl phenol is present in a plasticizing ratio, that is, a sufficient proportion to provide by itself or increase, with other plasticizer (s), a plasticizing effect. The proportion of alkylphenol to polyester depends on the proposed use of the composition.The scale 2-40 phr p / p includes more than likely uses.To manufacture effectively rigid but non-brittle articles, the scale 5-20, especially 6- 12, phr p / p The polyester, alkylphenol and relative proportions thereof are preferably chosen to provide at least 30, especially at least 50% inhibition of polyester talisation. Said composition preferably has a parameter flvrami '.' of less than 0.03, especially less than 0.01. In addition, its DSC crystallization peak preferably has an area of less than 20, especially less than 5 percent of that of the same plasticizer-free polyester. Said preferred compositions exemplify a new polyester composition defined in terms of only these parameters, and constitutes a second aspect of the invention. The composition may contain components commonly used in plastics treatments, for example: (a) one or more other plasticizers than the defined alkylphenol. (b) one or more stabilizers against thermal or oxidative decomposition. (c) inorganic filler, for example fiberglass, carbon fiber, flaky or laminated particles, silica, clay, magnesium silicate. (d) organic filler, for example fiber or cellulose particles, protein fiber, particles or synthetic polymer fiber, wood flour. (e) other polymers than polyester. (f) pigment. (g) nucleating, especially boron nitride, talcum, ammonium chloride or DZB / Zinc stearate, preferably at 0.2 to 2.0 phr. (h) Volatile solvent for polyester and alkylphenol.

If another plasticizer is present, may be selected from those already known for these polyesters and / or from any found for plasticizers after this invention. Examples are: (a) high-boiling polybasic acid esters, such as phthalates, isophthalates, citrates, furnarates, glutarate, phosphates or phosphites. The esterified radicals can be, for example, C 1 -C 12 alkyl, aryl or aralkyl. Particular examples are dioctyldiheptyl- and diundecyl phthalates and dialkylalkylene oxide glutarate.

(Plasthall 7050); (b) high boiling point esters and partial esters of polyhydric alcohols, especially glycols, polyglycols and glycerol. Examples are triacetin, diacetin and glyceryl dibenzoate. (c) aromatic sulfonarnides such as co or paratoluenesulfonamide.

A particularly preferred plasticizer is a dually esterified hydroxycarboxylic acid having at least three ester groups in its molecule. Doubly esterified "means that at least part of the hydroxyl groups of the hydroxycarboxylic acid are esterified with a carboxylic acid and at least part of the carboxyl groups thereof are esterified with an alcohol or phenol.

Preferably, at least the hydroxycarboxylic acid from which the ester is derived is aliphatic or cycloaliphatic. Its basic structure (that is, apart from the carboxyl groups) preferably contains from 2 to 6 carbon atoms. It preferably contains 2-4 carboxyl groups and 1-3 hydroxyl groups; and preferably the number of carboxyl groups exceeds the number of hydroxyl groups. An example of such a plasti- fizer is Staflex »(acetyltrin-n-butyl citrate). Registered trademark of AKZO. In accordance with a further aspect of the invention, a method for making the composition comprises mixing the polyester with the alkylphenol. This can be effected, for example, by means of: (i) Mixing the alkylphenol with the polyester in the form of particles, for example in particles smaller than 1000, especially smaller than 100 microns. Preferably, the particles are on a size scale of 0.1 to 50 microns. The particles are especially those obtained by enzymatic removal of cellular material other than polyester, such as protein, from a biomass produced microbiologically. The alkylphenol can be introduced at any convenient stage, including the steps before the particles are isolated from the aqueous medium. (ii) Melt a polyester mixture with alkylphenol.

The mixing is preferably done by means of method (i). Other components may be present, for example as in (a) to (d) above, especially those that aid fusion. (iii) Put the polyester and alkylphenol together in a volatile solvent for the polyester. The solvent can be introduced as a means of extracting the polyester from a microbiologically produced biomass or an intermediate product from which microbiological cellular material has been partially removed. Then the solvent can be eliminated or not, according to the requirements of the subsequent treatment. Suitable solvents include esters of cyclic carbonates and halogenated hydrocarbons such as dichloromethane, chloroform and 1,2-dichloroethane. A particular treatment comprises: (i) forming a biomass of cells containing PHf1 granules and cellular material different from PHA by fermentation. (ii) Treat the biomass to solubilize cellular material different from PHA. (iii) Separate the PHA granules from the liquid phase. And it is characterized by the introduction of at least one alkylphenol as defined above.

The process may include treating the granules with a peroxide to thereby solubilize cellular material other than additional PHfl to that which has been solubilized in step (ii), and separate the granules from the resulting liquid phase. In a further aspect of the invention there is provided a method for manufacturing an article formed by confining, for example, in a mold or on a surface or through a die, a composition as defined above. Particular methods include injection molding, compression molding, fiber or film extrusion, profile extrusion, gas winding, dot winding, coating on substrate, any of these carried out, as appropriate, using the composition in the molten mixture form, particle or solution in volatile solvent. Examples of shaped articles made by such methods include films especially for packaging, coated products (such as paper, cardboard and non-woven fabrics), fibers, non-woven fabrics, extruded networks, personal care products, bottles and beverage containers, films and containers of agriculture and horticulture, devices of delayed release and bags of ostomy. Alternatively, the composition can be used as an adhesive. The drawings that accompany this specification are as follows: Figure 1.- A family of DSC heating curves for control, reference and invention compositions. Figure 2.- DSC heating curves (a) and cooling curves (b) for pure polyester and composition containing 20ph of BHA. The following additional data refer to the curves shown in Figure 2.

No additives (a) Peak heating: 10B.73 ° C Peak 159.48 ° C to: 172.00 start 133.72 3 / g 65.14 ((bb)) EEnnffrriiaammiieennttoo P Piiccoo ddee :: 2 233..2233 °° CC Peak 52.97 ° C a: 82.15 start 66.36 3 / g 31.04 20phr of BHA ((aa)) CCaalleennttaammiieennttoo PPiiccoo of :: 8822..1100 °° CC Peak 126.46 ° C a: 150.71 start 110.17 3 / g 35.93 (b) Cooling (no additional data ) The invention is illustrated with the following experimental data by way of example.

TEST PROCEDURES: SERIES A PROPERTIES OF RECENT COMPOSITION Differential Scanning Calorimetry (DSC) Specimen Preparation The polyester and plasticizer (if used) was dissolved (totaling together l.Og) in chloroform (60 ml), heated to 50 ° C for 10 minutes then it was placed in a stainless steel tray (internal diameter 76.2 mm) and dried under vacuum. The resulting film was 0.2 to 0.28 mm thick. A specimen (approximately 4 mg) of the film was cut, placed in each aluminum depression of the DSC instrument and sealed. DSC test This technique measures the energy flow to or from a specimen compared to an inert reference as a function of time and temperature. A DSC instrument typically includes two thermally insulated supports in each of which a cavity is mounted containing respectively the test or reference specimen. The heat flow is measured and compensated to maintain the temperature with respect to the reference. The instrument can be operated in a dynamic mode under a pre-set temperature program or in isothermal mode. (i) A Perkin Elmer DSC-2 instrument equipped with a thermal analysis data station was used in the dynamic mode: Test 1: heat at 20 ° C min-i from 20 ° C to 200 ° C; Hold at 200 ° C for 1 minute to ensure that the sample is completely fused; cool down to minus 200 ° C rnin-1 to minus 80 ° C; Hold at minus 80 ° C for 10 minutes to preserve the amorphous state. Test 2: finally heat to 20 ° C min-i of less 80 to 200 ° C. The following parameters of the measured heat fluxes were derived: T Temperatura glass transition temperature (test 2); peak melting temperature TP (1) and Tp (2) for the two peaks observed; H fusion enthalpy. (ii) The DSC-2 instrument was operated in isothermal mode as follows: heat at 20 ° C min-i from 20 ° C to 200 ° C, hold for 10 minutes at 200 ° C to fuse; cool down 57 ° C quickly, - hold at 57 ° C, registering crystallization peak (s).

The results were analyzed by computer loaded with an isothermal program DSC-2C / 4 and then additionally in terms of the Avrami equation? = exp i -kt ") where? is the fraction of uncrystallized material that remains after the time t, k is a velocity constant, and n is the Ovra i exponent, which is usually considered to be characteristic of the nucleation mode. Tension test According to parameter K6301 of Japanese industry, a film of 0.2 nm thick as that made for DSC (see above) was cut into dumbbell pieces of No. 3 with central dimensions 5 x 20 x 0.2 mm. These were tested at 0.2 mm sec-1 on a TA-XT2 machine from Stable Micro Systems, Haslemere, UK.

EXAMPLES Polyester compositions were prepared from a PHB of this specification: structure: PHBV 90:10 copolymer (formula 1, m = 3.1 average); molecular weight Mw477000; origin: glucose + propionic acid fermentation by fllcaligenes eutrophys; extraction: removal of enzymatic cell debris. The compositions tested were as follows: Control - without additive Reference - known plasticizer triacetin TA Invention - BHfl Invention - BHT Invention - aT Invention - 6-T Each additive was used at 10, 20 and 30% w / w, ie 11 : 11, 25 and 42.86 phr. The results were as follows: The results of the DSC of the second test in dynamic mode are shown in table 1. (Note: the H values have been recalculated to give energies relative to the amount of polymer present. for example only 70% polymer).

TABLE 1 (Tfl I -47.9! 118.5 140.4 I 15.21 The following effects are observable: Tß: each additive of the invention decreases T 9, but less strongly than triacetin. The tocopherols appear to give a stronger effect per unit weight of phenolic OH. TP: similarly a decrease in the melting temperature was observed. This is again characteristic of plasticized systems. H: The enthalpy of fusion is indicative of the level of crystallinity obtained by the polymer during the DSC. Compositions containing BHA consistently give lower H values suggesting that crystallization was being inhibited.

The results of the second DSC test for compositions containing 30% additive are also shown in Figure 1. It is evident that a strong crystallization exotherm occurs in the unplasticized polyester and in the triacetin composition. However, this exotherm is weak in the composition containing acetate aT, very weak in compositions containing BHT and dT, and substantially absent in those containing BHA and aT. It is concluded that the plasticization in the compositions of the invention is by a mechanism different from that effective in the triacetin composition. This is confirmed by the flvrami parameters: the following was calculated: The k values imply that the recrystallization rate of the PHBV has been drastically decreased, but the n values show that the recrystallization mechanism has not changed. The heating (a) and cooling (b) curves of DSC for the unplasticized polyester and the composition containing 20 phr of BHA are shown in figure 2. From the heating curves it is evident that the area under the peak of Fusion is divided in half by the plasticizer. The cooling curves show a strong exotherm for the unplasticized polyester, but no sign of crystallization in the composition. Stress test The effect on elongation at the point of rupture (ETB) is shown in table 2: TABLE 2 TEST PROCEDURES: SERIES B CHANGE OF PROPERTIES OVER TIME The following properties were determined by normal procedures at 90 days after preparation of the compositions: Young's modulus (YM) MPa Breaking stress (SAB) MPa Displacement at rupture (DAB)% Impact force of IZOD (IZOD) Jm-i. The tested composition consisted of: PHVB copolymer with a B: V molar ratio of 93: 7 but otherwise similar to the polymer used in the A-series tests; plasticizer of 20phr p.p (if used); boron nitride nucleate of 1 phr p / p.

The plasticizers used were: none (control); flacetil-tri-n-butyl-citrate (RTBC) (control) BHfl BHfl + flTBC 10 phr w / each a-T The results are shown in table 3.

TABLE 3 Plasticizer The following conclusions can be drawn: From YM: the plasticized compositions are distinctly less tense than the unplasticized composition; since the BHA / ATBC mixture is less effective than an equal proportion of any plasticizer used alone, it appears that it acts by different mechanisms; a-T is less effective than BHA, but this may be due to its high molecular weight for phenolic OH (a-T 430, BHfl 180). From SflB to DAB: the plasticizers of the invention are at least equal to the known flTBC; From IZOD: the BHfl and BHfl. flTBC are approximately equal but lower than BHfl alone. The lower impact force using a-t can be correlated with its high molecular weight by phenolic OH.

Claims (14)

7 NOVELTY OF THE INVENTION CLAIMS

1. - A polymer composition consisting of: a) a stereospecific polyester of molecular weight over 100000 consisting of repeating units of formula-0-Cß, Hn-CO - in which n = 2m and units with m = 3 and m = 4 with respectively a side group of Ci and C2 at the carbon atom close to oxygen in the polymer chain copolyzed to each other, m being 3 at 70-95 mole percent of such units; and b) at least one alkylphenol.

2. A composition according to claim 1, wherein the alkylphenol consists of at least one alkyl group containing a chain of 2-10 carbon atoms and at least one alkyl group contains at least one atom of tertiary carbon.

3. A composition according to claim 2, in which the tertiary carbon atom is bound to two substituent atoms which are not hydrogen, at least one of such atoms is carbon and in which any substituent which does not be carbon is oxygen.

4. A composition according to any of the preceding claims, wherein the alkyl group chain carries 2-6 Ci-β alkyl group as side substituents.

5. A composition according to claim 4, wherein the side substituents are methyl.

6. A composition according to any of claims 2 to 5, wherein a tertiary carbon atom is adjacent to or within 4 carbon atoms of the phenol core.

7. A composition according to any of the preceding claims, wherein the alkylphenol is clogged.

8. A composition according to claim 7, wherein the alkyl phenol also contains an alkoxy group of C? - & in the para position with respect to the phenolic hydroxy group.

9. A composition according to claim 1, wherein the alkylphenol is selected from: a) 2-tert-butyl-4-hydroxyanisole, b) 3-tert-butyl-4-hydroxyanisole, c) mixture of a and b , d) 3,5-di-tert-butyl-4-hydrotoluene, e) alpha-tocopherol, f) delta-tocopherol, g) 2,2'-dihydroxy-5-5'-dimethoxy-3,3'- di-tert-butylbiphenol.

10. A composition according to any of the preceding claims, wherein the alkylphenol is chosen from those useful as antioxidants in food, oils and polymer systems.

11. A composition according to any of the preceding claims, wherein the polyester has been extracted from cells of a fermentation product by the decomposition of cellular material without PHR leaving microscopic polyester granules.

12. A composition according to any of the preceding claims, wherein the proportion of alkylphenol to polyester is in the range of 5-20 phr by weight.

13. A composition according to any of the preceding claims, wherein the polyester and alkylphenol and the relative proportions thereof are chosen to provide at least 30, especially at least 40 percent inhibition of crystallization of the polyester, which corresponds to a parameter 'k' of Avrami of less than 0.03, especially less than 0.02 and a peak of DSC crystallization area of less than 20, especially less than 5 percent of that of the same plasticizer-free polyester.

14. A composition according to any of the preceding claims, which also contains as an additional plasticizer a doubly esterified hydroxycarboxylic acid having at least 3 ester groups in the molecule.