Polymer composition for the manufacture of injection moulded articles

Abstract

This invention relates to a polymer composition that is particularly suitable for use in the manufacture of injection moulded articles, which can be biodegraded in industrial composting. This invention also relates to a process for the production of the said composition and articles obtained thereby.

Claims

1. A polymer composition for the production of injection moulded articles comprising, with respect to the sum of components i.-v.: i) 20-60% by weight of at least one polyester i. comprising: a) a dicarboxylic component comprising with respect to the total dicarboxylic component: a1) 0-20% in moles of units deriving from at least one aromatic dicarboxylic acid, a2) 80-100% in moles of units deriving from at least one saturated aliphatic dicarboxylic acid, a3) 0-5% in moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; b) a diol component comprising, with respect to the total diol component: b1) 95-100% in moles of units deriving from at least one saturated aliphatic diol; b2) 0-5% in moles of units deriving from at least one unsaturated aliphatic diol; ii) 30-60% by weight of at least one polyhydroxyalkanoate ii.; iii) 0.01-5% by weight of at least one cross-linking agent and/or a chain extender iii. comprising at least one compound having di- and/or multiple functional groups comprising isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride, divinyl ether groups and mixtures thereof; iv) 0-10% by weight of at least one filler agent; v) 2-30% by weight of plant fibres.

2. The polymer composition according to claim 1, in which the said at least one polyester i. comprises an aliphatic polyester (AP), comprising a dicarboxylic component consisting of, with respect to the total moles of the dicarboxylic component, 95-100% in moles of units deriving from at least one saturated aliphatic dicarboxylic acid and 0-5% in moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid, and a diol component comprising, with respect to the total moles of the diol component, 95-100% in moles of units deriving from at least one saturated aliphatic diol and 0-5% in moles of units deriving from at least one unsaturated aliphatic diol.

3. The polymer composition according to claim 2, in which the said aliphatic polyester (AP) is selected from the group consisting of poly(1,4-butylene succinate), poly(1,4-butylene adipate), poly (1,4-butylene azelate), poly(1,4-butylene sebacate), poly(1,4-butylene adipate-co-1,4-butylene succinate), poly(1,4-butylene azelate-co-1,4-butylene succinate), poly(1,4-butylene sebacate-co-1,4-butylene succinate), and poly(1,4-butylene succinate-co-1,4-butylene adipate-co-1,4-butylene azelate).

4. The polymer composition according to claim 2, wherein the said aliphatic polyester (AP) is poly(1,4-butylene succinate).

5. The polymer composition according to claim 1, in which the said at least one polyhydroxyalkanoate ii. is selected from the group consisting of polyesters of lactic acid, poly--caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate, polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate, polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate 4-hydroxybutyrate.

6. An injection moulded article comprising the polymer composition according to claim 1.

7. The injection moulded article according to claim 6, selected from the group consisting of disposable cutlery, plates, cups, rigid containers, capsules for the dispensing of beverages, lids, covers, or containers for food which can be heated in conventional or microwave ovens.

8. A capsule-for the dispensing of beverages comprising the composition according to claim 1, having a THF content below 3 mg/kg.

9. The polymer composition according to claim 2, in which the said at least one polyhydroxyalkanoate ii. is selected from the group consisting of polyesters of lactic acid, poly--caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate, polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate, polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate 4-hydroxybutyrate.

10. The polymer composition according to claim 3, in which the said at least one polyhydroxyalkanoate ii. is selected from the group consisting of polyesters of lactic acid, poly--caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate, polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate, polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate 4-hydroxybutyrate.

11. The polymer composition according to claim 4, in which the said at least one polyhydroxyalkanoate ii. is selected from the group consisting of polyesters of lactic acid, poly--caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate, polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate, polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate 4-hydroxybutyrate.

12. An injection moulded article comprising the polymer composition according to claim 2.

13. An injection moulded article comprising the polymer composition according to claim 3.

14. An injection moulded article comprising the polymer composition according to claim 4.

15. An injection moulded article comprising the polymer composition according to claim 5.

16. A capsule for the dispensing of beverages comprising the composition according to claim 2, having a THF content below 3 mg/kg.

17. A capsule for the dispensing of beverages comprising the composition according to claim 3, having a THF content below 3 mg/kg.

18. A capsule for the dispensing of beverages comprising the composition according to claim 4, having a THF content below 3 mg/kg.

19. A capsule for the dispensing of beverages comprising the composition according to claim 5, having a THF content below 3 mg/kg.

20. An injection moulded article comprising the polymer composition according to claim 9.

21. The polymer composition according to claim 1, wherein the plant fibres are selected from cellulose fibres, wood flour, hemp fibre, lignocellulose residues originating from raw materials of plant origin.

22. The polymer composition according to claim 1, which comprises 0.1-9% by weight of at least one filler agent having a median diameter of less than 10 microns and being selected from talc, calcium carbonate, titanium dioxide and mixtures thereof.

Description

EXAMPLES

(1) Component i i=Poly(1,4-butylene succinate) (PBS) prepared according to the following method: 17150 g of succinic acid, 14000 g of 1,4-butandiol, 26.75 g of glycerine and 2.0 g of an 80% by weight ethanolic solution of diisopropyl triethanolamine titanate (Tyzor TE, containing 8.2% by weight of titanium) were added to a steel reactor having a geometrical capacity of 40 litres fitted with a mechanical stirring system, an inlet for nitrogen, a distillation column, a knock-down system for high boiling point components and a connection to a high vacuum system in a diol/dicarboxylic acid (MGR) molar ratio of 1.08. The temperature of the mass was gradually raised to 230 C. over a period of 120 minutes. When 95% of the theoretical water has been distilled off, 21.25 g of tetra n-butyl titanate (corresponding to 119 ppm of metal with respect to the quantities of poly1,4-butylene succinate that would be theorically obtainable by converting all the succinic acid fed to the reactor) were added. The temperature of the reactor was then raised to 235-240 C. and the pressure was gradually reduced to a value below 2 mbar over a period of 60 minutes. The reaction was allowed to proceed for the time required to obtain a poly(1,4-1,4-butylene succinate) with an MFR of approximately 7 (g/10 minutes at 190 C. and 2.16 kg), and the material was then discharged in the form of a filament into a water bath and granulated.

(2) Component ii ii=Ingeo 3251D polylactic acid (PLA), MFR 28.7/10 min (at 190 C., 2.16 kg).

(3) Component iii iii=masterbatch comprising 10% by weight of Joncryl ADR4368CS (styrene-glycidylether-methylmethacrylate copolymer) and 90% by weight of component ii.

(4) Component iv iv-1=micronised talc having a median diameter of 1.9 microns (ISO 13317-3), Mistron R10C commercial grade from Imerys. iv-2=CaCO.sub.3 Calcitec M/ALFA from Mineraria Sacilese s.p.a.

(5) Component v v=fibrillar cellulose fibre having a mean fibre length of 550 microns L/D=18 Alpha-Cel C10 commercial grade from International Fiber Europe NV.

Examples 1-2Production of Injection Moulded Articles Comprising the Composition According to this Invention; Examples 3-6 (Comparative)

(6) TABLE-US-00001 TABLE 1 Compositions in Examples 1-6 Components (% wt) Example i ii iii iv-1 iv-2 v 1 44.5 42 2 1.5 10 2 32.1 44.3 2 1.5 20.1 3 (comparative) 32.1 44.3 2 1.5 20.1 4 (comparative) 32.1 44.3 2 21.6 5 (comparative) 44.5 42 2 1.5 10 6 (comparative) 44.5 42 2 11.5

(7) The compositions in Table 1 were fed respectively to an Icma San Giorgio MCM 25 HT model co-rotating twin screw extruder under the following operating conditions:

(8) Screw diameter (D)=25 mm;

(9) L/D=52;

(10) Rotation speed=150 rpm (Example 1), 180 rpm (Example 2);

(11) Temperature profile=50-150-2009-1553 C.;

(12) Throughput 10.1 kg/h (Example 1), 7.1 kg/h (Example 2).

(13) The granules so obtained were then injection moulded on a Sandretto S7/60 model press in a mould for the production of capsules for the dispensing of beverages (external flange diameter 35.5 mm, external diameter of the capsule base 30.3 mm, side wall thickness 0.65 mm, height 22.2 mm), using the following operating conditions for injection moulding:

(14) Injection T C.=230 C. (Example 1), 200 C. (Example 2);

(15) Injection pressure=90 bar;

(16) Injection time=1.5 sec (Example 1), 2 sec (Example 2);

(17) Cooling time=2.7 sec (Example 1), 2.5 sec (Example 2);

(18) Cycle time=7.9 sec (Example 1), 7.5 sec (Example 2);

(19) Screw rotation speed=180 rpm (Example 1), 200 rpm (Example 2);

(20) Comparative examples 3 and 4 were obtained under the operational conditions employed in example 2, while comparative examples 5 and 6 were obtained under the operational conditions employed in example 1.

(21) Slabs (length 80 mm, width 70 mm, thickness 1 mm) were also injection moulded under the same operating conditions as mentioned above and from these were obtained bars (length 30 mm, width 6 mm, thickness 1 mm) which then underwent dynamic mechanical-torsional analysis (DMTA) in torsional mode using an Ares G2 rotational rheometer from TA Instrument. The samples were heated from 25 C. to 130 C. at 3 C./min imposing a deformation of 0.1% and a frequency of 1 Hz. The compositions moulded in this way were characterised at 70 C. (conditions representative of the dispensing of hot coffee) by sufficiently high G values (shown in the Table 2 below) to permit them to be used for the production of capsules for the dispensing of beverages having high dimensional stability under the conditions of the dispensing of hot beverages.

(22) TABLE-US-00002 TABLE 2 DMTA characterization Example G @ 70 C. (MPa) 1 90 2 83 3 (comparative) 42 4 (comparative) 51 5 (comparative) 52 6 (comparative) 56

(23) From the G values indicated in Table 2, the compositions of Examples 1 and 2 containing plant fibres show a higher resistance to deformation at 70 C. when compared to compositions comprising CaCO.sub.3 or talc (comparative Examples 3-6).