POLYLACTIC ACID COMPOSITE AND USE THEREOF

Abstract

The present invention discloses a polylactic acid composite and use thereof. The polylactic acid composite includes the following components: i) 50-85 parts by weight of polylactic acid; ii) 8 to 35 parts by weight of an inorganic filler; and iii) 0 to 8 parts by weight of a plasticizer; wherein the polylactic acid composite has an end carboxyl content of 12 to 51 molKOH/t. The present invention unexpectedly discovered through research that, by controlling an end carboxyl content of the polylactic acid composite within a range of 12 to 51 molKOH/t, the polylactic acid composite, under a condition of 60° C. and 60% humidity, with a test time of 30 days, has a ratio of a mass melt index MFI.sub.t=30 to an initial mass melt index MFI.sub.t=0 satisfying 3.5<η=MFI.sub.t=30/MFI.sub.t=0<5.1, which indicates that under the test conditions, the product has slow aging degradation, and the polylactic acid composite has a biodegradation rate greater than 90% after 12 weeks in the case where a thickness is 2.5 mm or less, and has suitable aging properties and excellent biodegradability.

Claims

1. A polylactic acid composite, characterized in that, comprises the following components in parts by weight: i) 50 to 85 parts by weight of polylactic acid; ii) 8 to 35 parts by weight of an inorganic filler; and iii) 0 to 8 parts by weight of a plasticizer; wherein the polylactic acid composite has an end carboxyl content of 12 to 51 molKOH/t.

2. The polylactic acid composite according to claim 1, wherein a measurement method of the end carboxyl content is as follows: using a mixed liquor of o-cresol and trichloromethane with a mass ratio of 7:3 as a solvent, measuring an end carboxyl value with a Metrohm Titrino series automatic potentiometric titrator, carrying out a measuring method using FZ/T 50012-2006 “Determination for end carboxyl content in polyester-titration analysis method”, rounding off a one decimal place after the decimal point of an end carboxyl value according to a rounding method.

3. The polylactic acid composite according to claim 1, wherein the end carboxyl content of the polylactic acid composite is 18 to 41 molKOH/t, preferably 28 to 36 molKOH/t.

4. The polylactic acid composite according to claim 1, wherein under a condition of 60° C. and 60% humidity, with a test time of 30 days, a ratio of a mass melt index MFI.sub.t=30 of the polylactic acid composite to an initial mass melt index MFI.sub.t=0 satisfies the following relationship:
3.5<η=MFI.sub.t=30/MFI.sub.t=0<5.1;
preferably, 3.9<η=MFI.sub.t=30/MFI.sub.t=0<4.7;
more preferably, 4.2<η=MFI.sub.t=30/MFI.sub.t=0<4.5; a mass melt index MFI of the polylactic acid composite is tested according to standard ASTM D1238, and test conditions are 190° C., 2.16 kg, with a unit of g/10 min.

5. The polylactic acid composite according to claim 1, wherein according to ISO 16929 (2013), the polylactic acid composite has a biodegradation rate greater than 90% after 12 weeks when a thickness is 2.5 mm or less.

6. The polylactic acid composite according to claim 1, wherein the inorganic filler is selected from one or a mixture of more of talcum powder, montmorillonite, kaolin, chalk, calcium carbonate, gypsum, calcium chloride, iron oxide, dolomite, silicon dioxide, wollastonite, titanium dioxide, silicate, and mica, preferably one or a mixture of more of talcum powder, calcium carbonate, and silicon dioxide.

7. The polylactic acid composite according to claim 1, wherein the plasticizer which is liquid at room temperature is selected from one or a mixture of more of glycerol, polyglycerol, ethylene glycol, polyethylene glycol-400, polyethylene glycol-600, polyethylene glycol-800, epoxy soybean oil, citrate, acetyl citrate, triacetyl glyceride, and dioctyl adipate.

8. The polylactic acid composite according to claim 1, wherein in parts by weight, the polylactic acid composite further comprises 0 to 10 parts by weight of a flexibilizer, and the flexibilizer is an aliphatic polyester or an aliphatic-aromatic copolyester.

9. The polylactic acid composite according to claim 1, wherein in parts by weight, the polylactic acid composite further comprises 0 to 4 parts by weight of the following other additive: a release agent, a surfactant, a wax, an antistatic agent, a dye, or other plastic additive.

10. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 1, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

11. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 2, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

12. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 3, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

13. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 4, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

14. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 5, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

15. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 6, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

16. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 7, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

17. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 8, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

18. An injection-grade, blister-grade, or extrusion-grade product comprising the polylactic acid composite according to claim 9, wherein the injection-grade, blister-grade, or extrusion-grade product includes tableware, toys, and stationery.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] The present invention is further described below by specific implementations, and the following embodiments are preferable implementations of the present invention, but the implementation of the present invention is not limited by the following embodiments.

[0034] The raw materials used in the present invention are all commercially available.

[0035] Performance Test Method:

[0036] biodegradation rate: according to ISO 16929 (2013), a thickness was 2.5 mm or less, and the biodegradation rate of the polylactic acid composite after 12 weeks was tested.

[0037] η: under a condition of 60° C. and 60% humidity, with a test time of 30 days, a ratio of a mass melt index MFI.sub.t=30 to an initial mass melt index MFI.sub.t=0, η=MFI.sub.t=30/MFI.sub.t=0, the lower the η value, the slower the aging degradation of the product, the better the aging resistance.

[0038] Mass melt index MFI: was tested according to standard ASTM D1238, and test conditions were 190° C., 2.16 kg, with a unit of g/10 min.

[0039] A measurement method of the end carboxyl content was as follows: a mixed liquor of o-cresol and trichloromethane with a mass ratio of 7:3 was used as a solvent, an end carboxyl value was measured with a Metrohm Titrino series automatic potentiometric titrator, a measuring method was carried out using FZ/T 50012-2006 “Determination for end carboxyl content in polyester-titration analysis method”, a one decimal place after the decimal point of an end carboxyl value was rounded off according to a rounding method.

Synthesis of Polylactic Acid

Embodiment A1

[0040] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.035 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.080 MPa, and slowly heated to 145° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.080 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 145° C. for 18 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0041] Acid end group value: 14 mgKOH/g.

[0042] Unit power consumption: 85 kw.Math.h/Kg.

Embodiment A2

[0043] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.035 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.080 MPa, and slowly heated to 145° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.080 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 145° C. for 13 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0044] Acid end group value: 19 mgKOH/g.

[0045] Unit power consumption: 63 kw.Math.h/Kg.

Embodiment A3

[0046] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.027 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.101 MPa, and slowly heated to 135° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.101 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 135° C. for 12 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0047] Acid end group value: 25 mgKOH/g.

[0048] Unit power consumption: 60 kw.Math.h/Kg.

Embodiment A4

[0049] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.027 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.101 MPa, and slowly heated to 135° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.101 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 135° C. for 9 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0050] Acid end group value: 31 mgKOH/g.

[0051] Unit power consumption: 52 kw.Math.h/Kg.

Embodiment A5

[0052] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.022 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.150 MPa, and slowly heated to 130° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.150 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 130° C. for 9 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0053] Acid end group value: 36 mgKOH/g.

[0054] Unit power consumption: 50 kw.Math.h/Kg.

Comparative Example B1

[0055] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.022 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.150 MPa, and slowly heated to 130° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.150 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 130° C. for 6 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0056] Acid end group value: 48 mgKOH/g.

[0057] Unit power consumption: 36 kw.Math.h/Kg.

Comparative Example B2

[0058] 20 mol of commercially available L-lactide was taken as a raw material, toluene was used as an organic solution, 0.035 mol of stannous octoate was added as a catalyst, and they were added into a 20 L stainless steel reactor, the reactor was depressurized to high vacuum of 0.065 MPa, and slowly heated to 145° C. Stirring was conducted for 1 hour to completely dissolve lactide. The toluene steam generated by heating was extracted, the vacuum was maintained at 0.065 MPa, and the reaction was stopped after the reaction was carried out at a constant temperature of 145° C. for 21 hours. After the pressure in the reactor became normal pressure, ethyl acetate was added to dissolve the solid in the reactor, and then was pour into a container for air dry. After the ethyl acetate solvent was completely evaporated, it was placed in a vacuum dryer for use.

[0059] Acid end group value: 9 mgKOH/g.

[0060] Unit power consumption: 92 kw.Math.h/Kg.

[0061] After polylactic acid, organic filler, plasticizer and calcium stearate were mixed evenly according to the formulas in Table 1, the mixture was put into a twin-screw extruder to extrude and pellet at 150° C. to 220° C. to obtain a polylactic acid composite. The performance test data is shown in Table 1.

TABLE-US-00001 TABLE 1 Performance test results of Embodiments 1-10 and Comparative examples 1-2 (parts by weight) Compa. Compa. Embodi- Embodi- Embodi- Embodi- Embodi- Embodi Embodi Embodi- Embodi- Embodi- ex. 1 ex. 2 ment 1 ment 2 ment 3 ment 4 ment 5 ment 6 ment 7 ment 8 ment 9 ment 10 A1 65 A2 65 A3 65 70 69 66 85 A4 65 A5 65 55 B1 65 B2 65 talcum 28 28 28 28 28 28 28 28 28 20 9 35 powder PEG 400 5 5 5 5 5 5 5 1 2 4 8 calcium 2 2 2 2 2 2 2 2 2 2 2 2 stearate acid end 10 55 30 25 40 17 48 37 30 33 43 45 group content of polylactic acid composite mol/kg η 3.1 5.8 4.2 3.9 4.6 3.5 5.0 4.6 4.4 4.5 4.8 5.1 biode- 87.8 97.5 92.3 91.8 94.2 90.2 96.8 94.0 94.1 94.5 95.3 97.8 gradation rate %

[0062] It can be seen from the results in Table 1 that, in the embodiments of the present invention, by controlling the end carboxyl content of the polylactic acid composite within a range of 12 to 51 molKOH/t, the melt index of the composite can be brought into a reasonable range under test conditions, and in the case where a thickness is 2.5 mm or less, the polylactic acid composite has a biodegradation rate greater than 90% after 12 weeks, and has suitable aging properties and excellent biodegradability. In comparative example 1, the end carboxyl content of the polylactic acid composite is lower than 12 molKOH/t, and the biodegradation rate of the composite is lower than 90%. In comparative example 2, the end carboxyl content of the polylactic acid composite is higher than 51 mol/kg, although the composite has a higher biodegradation rate, its melt index rises faster during the test cycle and has poor aging resistance.