A polyester composition, its preparation and use

Abstract

The present application relates to a kind of polyester compositions and its preparation method and application.The polyester composition includes the following weight parts of components: biodegradable polyester 40-91 parts by weight, polylactic acid 2-20 parts by weight, calcium carbonate 1-30 parts by weight, sheet inorganic filler 0.1-10 parts by weight, organic opening agent 0.1-2 parts by weight.The polyester composition of the present application has good anti "mouth sticking" performance and film dart impact performance by ultra-thin film high-speed blowing film technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biodegradable plastics, and particularly relates to a polyester composition and a preparation method and application thereof. BACKGROUND

[0002] Compared with traditional polyethylene plastics, since flexible biodegradable polyesters are mostly semi-crystalline materials (such as PBAT), the biodegradable plastics mainly composed of flexible biodegradable polyesters, polylactic acid and mineral fillers often crystallize slowly in the film blowing production process, resulting in slow film surface cooling, and often causing the problem of "punching sticking" when cutting bags, which affects the consumer experience.

[0003] With the development of the biodegradable plastics industry, high-speed film blowing and light weight thinning are the future trends of biodegradable film production, and the "punching sticking" problem under this trend will be more serious and needs to be broken through. The traditional polyethylene industry can add some polyethylene components with stronger crystallization performance to strengthen the film bubble stability, however, the biodegradable industry is not allowed to add polyethylene which is difficult to degrade in the biodegradable plastics, and the high-crystalline resin generally has weaker degradation performance, so other high-crystalline resins are also not suitable for the biodegradable industry.

[0004] At present, several ways are often used to solve the problem of punching sticking in the industry. From the preparation process, the film blowing speed can be reduced to strengthen the crystallization cooling, or the film is placed for two or three days before cutting the bag, or the film blowing machine height is increased to 6 meters or even more than 7 meters, and the workshop is strongly cooled to reduce the temperature and improve the cooling effect of the film. However, the first two ways affect the production efficiency to varying degrees, and the last way by modifying the height of the film blowing machine or strongly cooling the workshop will cause the constraints of the workshop space and the waste of cost.

[0005] Therefore, solving the problem of punching sticking from the formula level is a more feasible solution in industrial production. At present, a large amount of opening agent is often added to increase the slipperiness to solve the problem of punching sticking. However, the opening agent is mostly a small molecule, and has poor compatibility with the polymer, which can easily cause the drop of the falling dart impact performance. SUMMARY

[0006] In order to overcome the problem of imbalance between the anti-punching sticking performance and the film falling dart impact performance in the prior art, the primary object of the present application is to provide a polyester composition.

[0007] A further object of the present application is to provide a preparation method of the polyester composition.

[0008] A further object of the present application is to provide the application of the polyester composition in the preparation of a film.

[0009] The present application protects a polyester composition, comprising the following components in parts by weight:

[0010] biodegradable polyester 40-91 parts by weight,

[0011] polylactic acid 2-20 parts by weight,

[0012] calcium carbonate 1-30 parts by weight,

[0013] sheet-shaped inorganic filler 0.1-10 parts by weight,

[0014] organic opening agent 0.1-2 parts by weight;

[0015] The D98 particle size of the sheet-shaped inorganic filler is ≤16 μm;

[0016] The supercooling degree of the polylactic acid is 80-115 ℃;

[0017] The melting point of the organic opening agent is 55-120 ℃.

[0018] The polyester composition of the present application comprises biodegradable polyester and polylactic acid, the combination of the two imparts basic toughness and rigidity to the polyester composition, and a certain amount of calcium carbonate imparts processing stability to the polyester composition. In order to improve the impact mouth adhesion resistance of the polyester composition, sheet-shaped inorganic filler and organic opening agent are further added.

[0019] For the polyester composition of the present application, which is mainly biodegradable polyester and supplemented with polylactic acid, the sheet-shaped inorganic filler is the key component for impact mouth adhesion resistance. The D98 particle size of the sheet-shaped inorganic filler needs to be controlled within a certain range, so that the sheet-shaped inorganic filler is layered, stacked and uniformly dispersed in the polyester composition, on the one hand reducing the interaction between the molecular chains in the biodegradable polyester, preventing the adhesion of the biodegradable polyester, so that the films prepared from the polyester composition do not adhere to each other, and on the other hand reducing the impact on the impact resistance of the polyester composition.

[0020] The melting point of the organic opening agent needs to be controlled within a suitable range, so that the compatibility of the organic opening agent with the polyester composition is within an appropriate range, avoiding the phenomena of difficult sealing and falling dart impact reduction due to insufficient compatibility and excessive precipitation, or impact mouth adhesion caused by too high compatibility and inability to precipitate.

[0021] The main body of the polyester composition of the present application is semi-crystalline biodegradable polyester, which has poor crystallization performance and setting ability, and is prone to impact mouth adhesion. The present application can improve the above-mentioned defects by adding polylactic acid with a specific supercooling degree to the biodegradable polyester, so that the obtained polyester composition has good crystallization and setting performance, thereby having appropriate anti-adhesion, and also imparting appropriate rigidity to the polyester composition.

[0022] It can be seen that, by matching the flaky inorganic filler with a specific D98 particle size, the organic opening agent with a specific melting point, and the polylactic acid with a specific supercooling degree, the polyester composition obtained by the dual synergistic effect of promoting crystallization and promoting slip can quickly crystallize and shape the film bubble in the process of high-speed film blowing of ultra-thin film, and the film surface has a slip layer, while meeting the balance of anti-“mouth sticking” performance and thin film dart impact performance after high-speed film blowing of ultra-thin film.

[0023] The supercooling degree is the difference between the melting point (Tm) and the glass transition temperature (Tg), i.e. supercooling degree = Tm-Tg.

[0024] The melting point Tm is measured by using a DSC204 thermal analyzer of Netzsch Company in Germany, the sample is first heated from 30℃ to 220℃ at a heating rate of 10℃ / min, and then kept at 220℃ for 3min to eliminate thermal history, then cooled to 30℃ at a rate of 10℃ / min, and then heated to 220℃ at a rate of 10℃ / min to obtain the second melting curve of the sample, and the melting peak value of the curve is selected as the melting point.

[0025] The glass transition temperature Tg is measured by using a DSC204 thermal analyzer of Netzsch Company in Germany, protected by nitrogen, taking a sample with a mass of 5±1mg, first heating from 30℃ to 160℃ at a heating rate of 10℃ / min, and then keeping at 160℃ for 3min, then cooling to-110℃ at a rate of 20℃ / min, and then heating to 150℃ at a rate of 10℃ / min; the glass transition temperature Tg of the sample is taken from the second heating curve, and the intersection point of the extension line at the inflection point and the baseline is taken as the value of the glass transition temperature Tg.

[0026] The D98 particle size is measured by referring to the method of GB / T 19077.1 “Particle Size Analysis-Laser Diffraction Method”.

[0027] Specifically, the flaky inorganic filler is at least one of flaky talc, flaky montmorillonite and flaky mica, and is further preferably flaky talc, flaky montmorillonite or a combination thereof, and is further preferably talc.

[0028] Preferably, the D98 particle size of the flaky inorganic filler is ≤13μm.

[0029] Preferably, the organic opening agent is one or more of glycerol monostearate (monoglyceride), stearic acid-based erucamide, oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide and synthetic wax.

[0030] Preferably, the melting point of the organic opening agent is 60-115℃.

[0031] Preferably, the supercooling degree of the polylactic acid is 85-105℃.

[0032] Specifically, the polylactic acid is selected from one or more of PLLA, PDLA or PLLA / PDLA copolymer, and more preferably is PLLA / PDLA copolymer.

[0033] Preferably, the content of D-lactic acid in the polylactic acid is 0.1-10 mol% or 90-100% mol%, further preferably is 0.1-8 mol% or 92-100 mol%, and still further preferably is 0.1-5 mol% or 95-100 mol%.

[0034] In the present application, the polylactic acid can be commercially available or self-made. The self-made method can be as follows:

[0035] The ring-opening polymerization reaction of lactide is carried out by bulk polymerization to obtain the polylactic acid.

[0036] Specifically, the polylactic acid is PLLA, PDLA or PLLA / PDLA copolymer.

[0037] More specifically, when the polylactic acid is PLLA, the lactide is L-lactide; when the polylactic acid is PDLA, the lactide is D-lactide; and when the polylactic acid is PLLA / PDLA copolymer, the lactide is L-lactide and meso-lactide.

[0038] Preferably, the ring-opening polymerization reaction is carried out in the presence of a catalyst, which includes but is not limited to stannous octoate.

[0039] Specifically, the mass ratio of the catalyst to the lactide is 0.0001-0.01:100.

[0040] Preferably, the ring-opening polymerization reaction is carried out as follows: first at 130-140℃ and 1100-1300 Pa for 3-4 hours, and then at 160-180℃ and 250-350 Pa for 4-6 hours.

[0041] Preferably, the polylactic acid has a melt flow rate of 2-12 g / 10 min measured at 190℃ under a load of 2.16 kg.

[0042] In the present application, the melt flow rate can be measured according to the ISO 1133 standard.

[0043] Specifically, the biodegradable polyester is aliphatic-aromatic copolyester.

[0044] Specifically, the biodegradable polyester is a copolymer of a dibasic acid and / or an ester-forming derivative thereof and a dihydric alcohol.

[0045] The biodegradable polyester copolymerized from the commonly used dibasic acid and / or the ester-forming derivative thereof and the commonly used dihydric alcohol can be used in the present application.

[0046] In the present application, the biodegradable polyester can be commercially available or self-made. The self-made method can be as follows: mixing the dibasic acid and / or the ester-forming derivative thereof, the dihydric alcohol and the branching agent, first reacting at 180-200℃ for 2-8 hours, adding a catalyst, and then reacting at 230-250℃ and 250-350 Pa for 6-18 hours to obtain the biodegradable polyester.

[0047] Specifically, the branching agent includes but is not limited to glycerol. The amount of the branching agent is 0.03%-0.06% of the mass of the dibasic acid and / or the ester-forming derivative thereof.

[0048] Preferably, the catalyst includes but is not limited to tetrabutyl titanate. The amount of the catalyst is 0.01%-0.03% of the sum of the amounts of substances of the dibasic acid and / or the ester-forming derivative thereof and the dihydric alcohol.

[0049] Preferably, the molar ratio of the dibasic acid and / or the ester-forming derivative thereof to the dihydric alcohol is 1:(1.05-1.2).

[0050] Preferably, the dibasic acid is at least one of aliphatic dibasic acid or aromatic dibasic acid.

[0051] Further preferably, the aliphatic dibasic acid is at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid or dodecanedioic acid.

[0052] Further preferably, the aromatic dibasic acid is terephthalic acid.

[0053] More preferably, the dibasic acid is aliphatic dibasic acid and aromatic dibasic acid, and the molar ratio of the aromatic dibasic acid to the aliphatic dibasic acid is 1:(0.80-1.20); specifically, 1:0.8, 1:0.85, 1:0.87, 1:0.90, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.16 or 1:1.20.

[0054] Preferably, the dihydric alcohol is at least one of butanediol, propanediol, ethylene glycol or pentanediol.

[0055] Specifically, the biodegradable polyester can be at least one of polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), polybutylene succinate terephthalate (PBST), polybutylene adipate sebacate terephthalate (PBSeAT), polybutylene sebacate succinate terephthalate (PBSeST), polybutylene succinate adipate terephthalate (PBSAT), or polypropylene adipate terephthalate (PDAT).

[0056] The present application also finds that the content of terephthalic acid units in the biodegradable polyester is preferably controlled within a certain range, which can improve the crystallinity of the biodegradable polyester and obtain good anti-impact mouth adhesion performance, without affecting the drop dart performance and biodegradation rate to meet the requirements of biodegradable film.

[0057] Preferably, the content of terephthalic acid units (T content) in the biodegradable polyester is 45-55 mol%, more preferably 48-50 mol%.

[0058] Specifically, the melt flow rate of the biodegradable polyester at 190℃ under 2.16kg is 2-10g / 10min.

[0059] Preferably, the D50 particle size of the calcium carbonate is 1-5μm, preferably 2.3-5μm.

[0060] Specifically, the melt flow rate of the polyester composition measured at 190℃ under 2.16kg is 2-10g / 10min.

[0061] The present application also protects a preparation method of the polyester composition, comprising the following steps: mixing the components, melt extruding, and granulating to obtain the polyester composition.

[0062] The application of the polyester composition in preparing a full biodegradable film bag is also within the protection scope of the present application.

[0063] A full biodegradable film bag is prepared by the polyester composition.

[0064] Compared with the prior art, the present application has the following beneficial effects:

[0065] The polyester composition obtained by the cooperation of the specific D98 particle size of the sheet-shaped inorganic filler, the specific melting point of the organic opening agent, and the specific supercooling degree of the polylactic acid has good anti-impact mouth adhesion performance and film drop dart impact performance through the ultra-thin film high-speed blowing film technology. DETAILED DESCRIPTION

[0066] The application will be further described in connection with the following examples. These examples are only used to illustrate the application and are not used to limit the scope of the application. The experimental methods in the following examples, if not otherwise specified, are generally carried out according to the conventional conditions in the art or according to the conditions suggested by the manufacturers; the raw materials, reagents, etc. used, if not otherwise specified, are all commercially available raw materials and reagents. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application shall fall within the scope of the present application.

[0067] Some reagents used in the examples and comparative examples of the present application are described as follows:

[0068] Biodegradable polyester 1#: self-made, PBAT, prepared as follows: 1.919 kg of terephthalic acid, 1.966 kg of adipic acid, and excess 1,4-butanediol 2.548 kg and glycerol 2.3 g were all added to a 20 L reaction kettle, stirred at 190 ℃ for 3 hours, then 0.02% of the total molar ratio of acid and alcohol of tetrabutyl titanate was added as a catalyst, the temperature was raised to 240 ℃, and the reaction was carried out under vacuum pressure of 300 Pa for 7 hours to obtain PBAT. The melt flow rate of biodegradable polyester 1# was 3.8 g / 10 min, and the terephthalic acid content was 46.2 mol%.

[0069] Biodegradable polyester 2#: self-made, PBAT, prepared as follows: the difference between the preparation method of biodegradable polyester 1# and biodegradable polyester 2# is that 1.994 kg of terephthalic acid and 1.901 kg of adipic acid are used. The melt flow rate of biodegradable polyester 1# is 4.1 g / 10 min, and the terephthalic acid content is 49.8 mol%.

[0070] Polylactic acid 1#: self-made, prepared as follows: using bulk polymerization, taking 80 parts by weight of L-lactide (purity 99.6%) and 20 parts by weight of meso-lactide (purity 99.6%), adding 0.002 parts by weight of stannous octoate, and carrying out ring-opening polymerization: first at a reaction temperature of 135 ℃ and a reaction pressure of 1200 Pa for 4 hours, then at a reaction temperature of 170 ℃ and a reaction pressure of 300 Pa for 6 hours; underwater pelletizing, crystallizing, and drying to obtain polylactic acid 1#. The supercooling degree of polylactic acid 1# is 82.9 ℃, the type is PDLA / PLLA copolymer, and the melt flow rate is 4.2 g / 10 min.

[0071] Polylactic acid 2: self-made, the difference between the preparation method and polylactic acid 1 is that 82 parts by weight of L-lactide (purity 99.6%) and 18 parts by weight of meso-lactide (purity 99.6%) are taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. The supercooling degree of polylactic acid 2 is 86.7°C, the type is PDLA / PLLA copolymer, and the melt flow rate is 4.5 g / 10 min.

[0072] Polylactic acid 3: self-made, the difference between the preparation method and polylactic acid 1 is that 92 parts by weight of L-lactide (purity 99.6%) and 8 parts by weight of meso-lactide (purity 99.6%) are taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. The supercooling degree of polylactic acid 3 is 102.4°C, the type is PDLA / PLLA copolymer, and the melt flow rate is 3.9 g / 10 min.

[0073] Polylactic acid 4: self-made, the difference between the preparation method and polylactic acid 1 is that 99 parts by weight of L-lactide (purity 99.6%) and 1 part by weight of meso-lactide (purity 99.6%) are taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. First, it is reacted for 5 hours under the condition of a reaction temperature of 135°C and a reaction pressure of 1200 Pa, and then it is reacted for 9 hours under the condition of a reaction temperature of 170°C and a reaction pressure of 300 Pa. The supercooling degree of polylactic acid 4 is 104.8°C, the type is PLLA, and the melt flow rate is 2.1 g / 10 min.

[0074] Polylactic acid 5: self-made, the difference between the preparation method and polylactic acid 1 is that 100 parts by weight of D-lactide (purity 99.6%) is taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. First, it is reacted for 3 hours under the condition of a reaction temperature of 135°C and a reaction pressure of 1200 Pa, and then it is reacted for 5 hours under the condition of a reaction temperature of 170°C and a reaction pressure of 300 Pa. The supercooling degree of polylactic acid 5 is 114.7°C, the type is PDLA, and the melt flow rate is 6.4 g / 10 min.

[0075] Polylactic acid 6: self-made, the difference between the preparation method and polylactic acid 1 is that 74 parts by weight of L-lactide (purity 99.6%) and 26 parts by weight of meso-lactide (purity 99.6%) are taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. First, it is reacted for 3 hours under the condition of a reaction temperature of 135°C and a reaction pressure of 1200 Pa, and then it is reacted for 7 hours under the condition of a reaction temperature of 170°C and a reaction pressure of 300 Pa. The supercooling degree of polylactic acid 6 is 78.8°C, the type is PDLA / PLLA copolymer, and the melt flow rate is 4.3 g / 10 min.

[0076] Polylactic acid 7#: self-made, the difference between its preparation method and that of polylactic acid 1# is that 100 parts by weight of L-lactide (purity 99.9%) is taken, 0.002 parts by weight of stannous octoate is added, and ring-opening polymerization is carried out. The supercooling degree of polylactic acid 7# is 116.8°C, the type is PLLA, and the melt flow rate is 4.1 g / 10 min.

[0077] Polylactic acid 8#: manufacturer Anhui Fengyuan, brand FY804, supercooling degree 101.2°C, type PLLA / PDLA, melt flow rate 4.1 g / 10 min.

[0078] Calcium carbonate 1#: manufacturer Omya, brand 2T-JI, D50 particle size 2.5 μm.

[0079] Calcium carbonate 2#: manufacturer Omya, brand 1T-CU, D50 particle size 1.8 μm.

[0080] Flaky inorganic filler 1#: talc powder, manufacturer Liaoning Haisheng Chencheng, brand HTPUHItra5L, D98 particle size 8.1 μm.

[0081] Flaky inorganic filler 2#: talc powder, manufacturer Liaoning Aihai, brand AH-3000N9, D98 particle size 14.3 μm.

[0082] Flaky inorganic filler 3#: talc powder, manufacturer Liaoning Aihai, brand AH-1250N6, D98 particle size 19.8 μm.

[0083] Organic opening agent 1#: glycerol monostearate, manufacturer Binzhou Jinsheng, brand ST-101, melting point 58.5°C.

[0084] Organic opening agent 2#: synthetic wax, manufacturer SHELL company, brand Callista 144, melting point 61.3°C.

[0085] Organic opening agent 3#: erucamide, manufacturer Huitai Xipu Chemical, brand CRODAMIDE ER-CH-MB-(SI), melting point 80.1°C.

[0086] Organic opening agent 4#: behenic acid amide, manufacturer Lixheai (Shanghai) Chemical Industry Development Co., Ltd., brand D1007, melting point 112.8°C.

[0087] Organic opening agent 5#: synthetic wax, manufacturer Sasol company, brand Spray 105, melting point 117.2°C.

[0088] Organic opening agent 6#: synthetic wax, manufacturer SHELL company, brand Callista 122, melting point 54.1°C.

[0089] Organic opening agent 7: Vinyl bis stearamide, manufacturer Zhuhai Jinfa Supply Chain Management Co., Ltd., brand ESB50, melting point 142.0℃.

[0090] The polyester compositions of the embodiments and comparative examples of the present application are prepared by the following process:

[0091] The components are weighed according to the formula, mixed uniformly, and then put into a twin-screw extruder, melted and extruded at 180℃, and granulated to obtain the polyester composition.

[0092] The performance test method and standard of the polyester compositions of the embodiments and comparative examples of the present application are as follows:

[0093] The test method of melting point Tm is as follows: using DSC204 thermal analyzer of Netzsch Company in Germany, the sample is first heated from 30℃ to 220℃ at a rate of 10℃ / min, and kept at 220℃ for 3min to eliminate thermal history, then cooled to 30℃ at a rate of 10℃ / min, and heated to 220℃ at a rate of 10℃ / min to obtain the second melting curve of the sample, and the melting peak value of the curve is selected as the melting point.

[0094] The test method of glass transition temperature Tg is as follows: using DSC204 thermal analyzer of Netzsch Company in Germany, protected by nitrogen, taking a sample with a mass of 5±1mg, first heated from 30℃ to 160℃ at a rate of 10℃ / min, and kept at 160℃ for 3min, then cooled to-110℃ at a rate of 20℃ / min, and heated to 150℃ at a rate of 10℃ / min; the glass transition temperature Tg of the sample is taken from the second heating curve, and the intersection point of the extension line at the inflection point with the baseline is taken as the value of the glass transition temperature Tg.

[0095] The test method of D98 particle size is determined by referring to the method of GB / T 19077.1-2016 "Particle size analysis-laser diffraction method".

[0096] The melt flow rate is measured by ISO 1133-1-2011 standard, and the melt flow rate test conditions are 190℃, 2.16kg.

[0097] The test method for die lip adhesion is as follows: a single screw film blowing machine is used for the test, a die gap of 2.0 mm is used, the die diameter is 70 mm, the blow-up ratio is 3.0, the setting temperature is 150℃, the film blowing frequency is 40 Hz, the film thickness is controlled at 25±2 μm, the bag is cut within 1 hour of film blowing, and the die cutter tip thickness is 0.1-0.2 mm. After die cutting, the rating is evaluated according to the rating criteria in Table 1, and the intermediate rating can be punched, such as 1.5 if it is between 1 and 2, and the same applies. The number of evaluators is five, and the average of the ratings of the five evaluators is taken as the final rating.

[0098] Table 1 Rating criteria for die lip adhesion

[0099] Rank / Class Definition Description 1 No Adhesion Die opens naturally, film surface is not damaged, no external force is needed 2 Slight Adhesion Opens with light hand rubbing, film surface is not damaged, minimal external force is needed 3 Moderate Adhesion Opens with hand rubbing and pulling, film surface is not damaged, moderate external force is needed 4 Obvious Adhesion Opens with hand rubbing and pulling, film surface is damaged at the edges, moderate external force is needed 5 Severe Adhesion Completely adhered and cannot be separated, film surface is significantly damaged with external force

[0100] The test method for dart impact strength is as follows: the GB / T 9639.1-2008 standard is referred to.

[0101] Examples 1-15

[0102] Examples 1-15 provide a series of polyester compositions, the weight parts of each component in the formula of which are shown in Table 2 and Table 3.

[0103] Table 2 Formula of Examples 1-8 (weight parts)

[0104]

[0105] Table 3 Formula of Examples 9-15 (weight parts)

[0106]

[0107]

[0108] Comparative Examples 1-7

[0109] Comparative Examples 1-7 provide a series of polyester compositions, the weight parts of each component in the formula of which are shown in Table 4.

[0110] Table 4 Formula of Comparative Examples 1-7 (weight parts)

[0111]

[0112] The properties of the polyester compositions of each example and comparative example are measured according to the test methods mentioned above, and the test results are shown in Table 5.

[0113] Table 5 Test results of the properties of the polyester compositions of each example and comparative example

[0114] Test Results Die Adhesion Rank / Class Dart Impact Strength / g Example 1 1.4 164.6 Example 2 1.0 122.5 Example 3 1.9 328.5 Example 4 1.2 144.5 Example 5 1.3 150.4 Example 6 1.0 130.2 Example 7 1.1 129.8 Example 8 1.2 120.5 Example 9 1.5 187.3 Example 10 1.6 157.5 Example 11 1.3 178.5 Example 12 1.0 216.8 Example 13 1.3 189.3 Example 14 1.5 217.8 Example 15 1.0 135.8 Comparative Example 1 3.9 200.2 Comparative Example 2 2.1 58.2 Comparative Example 3 2.1 38.9 Comparative Example 4 1.3 35.9 Comparative Example 5 4.5 212.2 Comparative Example 6 1.8 68.9 Comparative Example 7 3.8 199.2

[0115] From Table 5, it can be seen that:

[0116] The polyester composition of each embodiment has a die adhesion level of ≤N2 and a dart impact strength of ≥100g when the polyester composition is made into a film bag with a film thickness of 25±2μm by the ultra-thin film high-speed film blowing technology, indicating that the ultra-thin film bag made of the polyester composition has good die adhesion resistance and dart impact strength.

[0117] The supercooling degree of the polylactic acid added in Comparative Example 1 is too low, although the polylactic acid has good compatibility with the blending system, the viscosity of the system is too high, resulting in a poor anti-adhesion level of 3.9, which does not meet the use. The supercooling degree of the polylactic acid added in Comparative Example 2 is too high, the compatibility of the polylactic acid with the blending system is poor, and the dart performance is greatly reduced to only 58.2g, which does not meet the use. The D98 particle size of the sheet-shaped inorganic filler added in Comparative Example 3 is too large, resulting in more defect points in the microfilm of the blending material, and the dart performance is greatly reduced to only 38.9g, which does not meet the use. The melting point of the organic opening agent added in Comparative Example 4 is too low, and the compatibility with the system is poor, which is quickly precipitated on the film surface, although it has a certain help for anti-adhesion, but the dart impact strength is only 35.9g, which does not meet the use. The melting point of the organic opening agent added in Comparative Example 5 is too high, which is difficult to precipitate the film to play the effect of smoothness, and the anti-adhesion effect is poor, only 4.5, which does not meet the use; Comparative Example 6 does not add calcium carbonate, only sheet-shaped inorganic filler, and the dispersibility of the sheet-shaped inorganic filler is not as good as that of calcium carbonate, so the dart performance is poor; Comparative Example 7 does not add sheet-shaped inorganic filler, and the powder content on the surface of the film is small, so the anti-adhesion effect is poor.

[0118] Obviously, the above embodiments of the present application are merely exemplary and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A polyester composition, characterized in that, The components include the following parts by weight: 40-91 parts by weight of biodegradable polyester Polylactic acid 2-20 parts by weight Calcium carbonate 1-30 parts by weight 0.1-10 parts by weight of flake-shaped inorganic filler. 0.1-2 parts by weight of organic opening agent; The D98 particle size of the sheet-like inorganic filler is ≤16μm; The supercooling of the polylactic acid is 80~115℃, and the supercooling is the difference between the melting point and the glass transition temperature. The organic opening agent has a melting point of 55~120℃; The biodegradable polyester is an aliphatic-aromatic copolyester; The sheet-like inorganic filler is one or more of talc, montmorillonite, and mica.

2. The polyester composition according to claim 1, characterized in that, The D98 particle size of the sheet-like inorganic filler is ≤13μm.

3. The polyester composition according to claim 1, characterized in that, The organic opening agent is one or more of the following: glyceryl monostearate, stearyl erucamide, oleamide, erucamide, stearamide, behenamide, and synthetic wax.

4. The polyester composition according to claim 1 or 3, characterized in that, The organic opening agent has a melting point of 60~115℃.

5. The polyester composition according to claim 1, characterized in that, The polylactic acid is selected from one or more of PLLA, PDLA, or PLLA / PDLA copolymer.

6. The polyester composition according to claim 1 or 5, characterized in that, The supercooling degree of the polylactic acid is 85~105℃.

7. A method for preparing the polyester composition according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing the components, melt extruding, and granulating to obtain the polyester composition.

8. The use of the polyester composition according to any one of claims 1 to 6 in the preparation of fully biodegradable film bags.

9. A fully biodegradable membrane bag, characterized in that, It is prepared by any of the polyester compositions according to claims 1 to 6.

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