A CaCO3 / PBAT high-filling masterbatch and a preparation method thereof, and a PBAT film prepared from the masterbatch

Abstract

The present invention discloses a CaCO3 / PBAT high-filling masterbatch, a preparation method thereof, and a PBAT film prepared by the masterbatch. The preparation method of the CaCO3 / PBAT high-filling masterbatch comprises the following steps: (1) boiling ordinary PBAT pellets by heating; (2) draining the boiled PBAT pellets and drying them by blast drying to obtain dried PBAT particles; (3) mixing the dried PBAT particles with calcium carbonate powder and ordinary PBAT pellets, mixing them by a high mixer and extruding them by a twin-screw extruder to obtain the CaCO3 / PBAT high-filling masterbatch. The present invention provides a PBAT film obtained by mixing ordinary PBAT pellets and CaCO3 / PBAT high-filling masterbatch and blowing the film. The present invention is simple, pure, and efficient, and ultimately achieves the purpose of improving the mechanical properties of the PBAT film.

Description

Technical Field

[0001] The invention relates to filling and modification of biodegradable plastics, and in particular to a CaCO3 / PBAT high-filling masterbatch and a preparation method thereof, and a PABT film prepared using the masterbatch. Background Art

[0002] PBAT is a copolymer of adipic acid-butylene glycol-terephthalic acid, which has good tensile strength and elongation at break, and also has excellent biodegradability. The films prepared with it are widely used in packaging, agriculture, forestry, medical and health fields. However, it is difficult to process films directly made of pure PBAT and the cost is high, so some fillers are often added to improve its processing performance and reduce costs. Calcium carbonate is an important inorganic filler, widely used in rubber, plastics, papermaking, coatings, inks, building materials and other industries. At present, calcium carbonate is often used to fill PBAT in the biodegradable plastic industry.

[0003] Since calcium carbonate is a hydrophilic inorganic salt, it contains hydroxyl groups on the surface, has poor affinity with plastics, and the mechanical properties of the filled modified material are poor. Therefore, it is necessary to modify the surface of calcium carbonate to be hydrophobic and oleophilic. Common methods include: 1. Coupling agent modification; 2. Stearic acid modification; 3. Polymer coating, that is, using polyvinyl pyrrolidone (PVP) and other materials to coat calcium carbonate. Common processes include 1. Pre-modification and then adding to the resin melt; 2. Directly melt and mix calcium carbonate, resin, and modifying / coating agent for in-situ modification.

[0004] The above modifications are either costly, or generally incompatible with the matrix resin, or have small molecule residues, or the coating agent itself (such as PVP, etc.) does not degrade, resulting in the lack of market competitiveness of PBAT modified and filled by these methods. In particular, fillers are difficult to use in areas of direct food contact. Theoretically, the modifier with the best compatibility with PBAT is PBAT. If there is an ultra-short chain of PBAT, and its terminal carboxyl group is used to modify the surface of calcium carbonate, the calcium carbonate / PBAT filler will undoubtedly have the characteristics of purity and good mechanical properties. It is expected to be used in food packaging. Summary of the invention

[0005] The primary purpose of the present invention is to provide a simple, low-cost, pure and efficient method for preparing CaCO3 / PBAT high-filling masterbatch.

[0006] A second object of the present invention is to provide a method for preparing a CaCO3 / PBAT highly filled masterbatch.

[0007] The third object of the present invention is to provide a PBAT film prepared using CaCO3 / PBAT high-filling masterbatch.

[0008] The present invention specifically adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing a CaCO3 / PBAT high-filling masterbatch by in-situ modification of calcium powder with short-chain PBAT, comprising the following steps:

[0010] (1) Boil ordinary PBAT pellets at 85-98°C for 36-72h, stirring continuously during the boiling process to ensure uniform heating;

[0011] (2) draining the boiled PBAT pellets obtained in step (1), and drying them with forced air at 60-70° C. for 12-15 h to obtain dried PBAT particles;

[0012] (3) The dried PBAT particles obtained in step (2) are mixed with calcium carbonate powder and ordinary PBAT pellets, mixed by a high-speed mixer and extruded by a twin-screw extruder to obtain a CaCO3 / PBAT high-filler masterbatch; wherein the mass percentages of the dried PBAT particles and the calcium carbonate powder are 2.5-10% and 60-80%, respectively, based on the total mass of the dried PBAT particles, the calcium carbonate powder and the ordinary PBAT pellets being 100%.

[0013] In the technical scheme of the present invention, after ordinary PBAT resin pellets are boiled and melt-extruded, the PBAT molecular chain is hydrolyzed and shortened to obtain a PBAT with low molecular weight and ultra-high melt flow rate (MFR) (hereinafter referred to as short-chain PBAT), and its molecular chain ends have hydroxyl and carboxyl groups. The present invention adds the boiled and dried PBAT particles to the conventional formula of calcium carbonate powder and ordinary PBAT, and realizes the uniform dispersion of short-chain PBAT in the material system through a high mixer and a twin-screw extruder; the calcium carbonate powder is in situ modified by the reaction of the short-chain PBAT end carboxyl group and the calcium ion on the surface of the calcium powder, and the short-chain PBAT is completely compatible with the normal PBAT, and finally the purpose of improving the interfacial force of the CaCO3 / PBAT high-filler masterbatch and the mechanical properties of the PBAT film is achieved. The high filling described in the present invention refers to the mass content of calcium carbonate in the CaCO3 / PBAT high-filler masterbatch being above 30%, preferably 60-80%.

[0014] In the present invention, the content of short-chain PBAT directly affects the modification effect of calcium powder and the mechanical properties of the final film product, and should be maintained within an appropriate range.

[0015] Preferably, the particle size of the calcium carbonate powder is 1000-2000 mesh.

[0016] Preferably, based on the total mass of the dried PBAT particles, calcium powder and common PBAT granules being 100%, the mass percentage of the dried PBAT particles is 5%.

[0017] Preferably, the boiling time of PBAT in step (1) is 36-48 hours, more preferably 48 hours.

[0018] Preferably, in step (3), the mixing conditions in the high-speed mixer are: 10-15 min, 80-90° C., 800-1000 r / min.

[0019] Preferably, in step (3), the extrusion conditions of the twin-screw extruder are: 140-170°C, 300-400r / min.

[0020] The common PBAT described in the present invention is unmodified PBAT granules purchased from the market, and the calcium carbonate powder is commercially available calcium carbonate. The reaction between the short-chain PBAT terminal carboxyl group and the calcium ion on the surface of the calcium carbonate powder refers to the following reaction:

[0021]

[0022] This reaction does not require a catalyst and can proceed at a certain temperature.

[0023] In a second aspect, the present invention provides a CaCO3 / PBAT high-filling masterbatch prepared according to the preparation method described in the first aspect.

[0024] In a third aspect, the present invention provides a PBAT film, wherein the PBAT film is obtained by mixing ordinary PBAT pellets and CaCO3 / PBAT high-filler masterbatch in a certain mass ratio and blowing the mixture.

[0025] Preferably, the mass ratio of CaCO3 / PBAT high-filler masterbatch to ordinary PBAT pellets is 1:2-1:1, more preferably 1:1.667.

[0026] Preferably, the film blowing conditions are: film blowing temperature 140-160° C., screw speed: 5-10 Hz, and traction speed: 6-12 m / min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The short-chain PBAT of the present invention can effectively anchor the surface of calcium powder and enhance the dispersibility of calcium powder in the system.

[0029] (2) The preparation method of the short-chain PBAT of the present invention is simple, and the calcium powder does not need to be modified with a coupling agent, which has lower cost.

[0030] (3) The method for preparing high-filling masterbatch with short-chain PBAT modified calcium powder of the present invention is simple, pure, and efficient, and does not introduce small molecule additives and non-degradable polymer coating agents, and is particularly suitable for the production of PBAT films that directly or indirectly contact food.

[0031] (4) The present invention in situ modifies calcium carbonate powder by reacting the end carboxyl groups of short-chain PBAT with calcium ions on the surface of calcium powder. At the same time, short-chain PBAT is completely compatible with normal PBAT, thereby ultimately achieving the purpose of improving the mechanical properties of PBAT film. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of calcium powder surface modified by short-chain PBAT end carboxyl groups. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the present invention, not all of it. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] 1 kg of ordinary PBAT pellets (Hengli Group, KHB21AP11, MFR is 3.8 g / 10 min (190 ° C, 2.16 kg)) was placed in a water pot and fully stirred and heated (95 ° C, 36 h). The resulting PBAT particles were fished out, drained, and then placed in a blast oven at 60 ° C for 12 h. After the PBAT particles were dried, the melt flow rate (MFR) instrument was used to test its MFR, which was 200 g / 10 min (190 ° C, 2.16 kg).

[0036] After obtaining the boiled PBAT particles, the addition amount is 2.5% of the total material mass, the addition amount of calcium carbonate powder (1500 mesh) is 80% of the total material mass, and the addition amount of ordinary PBAT pellets is 17.5% of the total material mass. Mix in a high mixer (SHR-100A, Zhangjiagang Xinyuan Machinery) for 10 minutes (80°C, 800r / min) to obtain a uniformly mixed material. The material is extruded (140-170°C, 300r / min) by a parallel twin-screw extruder (SHJ-35B, Nanjing Juli Chemical Machinery) to obtain a CaCO3 / PBAT high-filling masterbatch modified with short-chain PBAT calcium powder. The masterbatch is evenly mixed with ordinary PBAT pellets at a mass ratio of 1:1.667, and the required film is made by blowing a film (140-165°C, 5Hz, 6m / min) through a film blowing machine (VN-HM45B, Aoxiang Machinery).

[0037] Comparative Example 1: Preparation of a film made from a masterbatch without adding short-chain PBAT

[0038] Same as Example 1, but without adding short-chain PBAT, the addition amounts of ordinary PBAT and calcium carbonate powder were 20% and 80% of the total material mass, respectively.

[0039] Finally, the mechanical properties of the prepared film were tested, and the results are shown in Table 1. It shows that without adding short-chain PBAT, the tensile strength of the blown film prepared after the masterbatch was diluted is low, and the addition of short-chain PBAT does have an effect on the modified calcium powder, and the tensile strength of the film is improved.

[0040] Table 1

[0041] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 1 21.2 396

[0042] Embodiment 2:

[0043] Same as Example 1, but the addition amount of short-chain PBAT was increased to 5% of the total material mass, and the addition amount of ordinary PBAT was 15% of the total material mass. The results are shown in Table 2 below. It shows that increasing the amount of short-chain PBAT has a more obvious modification effect on calcium powder, and the tensile strength of the film is improved.

[0044] Table 2

[0045] <![CDATA[CaCO3 / PBAT thin film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 1 21.2 396 Example 2 23.2 484

[0046] Embodiment 3:

[0047] Same as Example 1, but the addition amount of short-chain PBAT was increased to 10% of the total material mass, and the addition amount of ordinary PBAT was 10% of the total material mass. The results are shown in Table 3 below. It shows that the increase in the tensile strength of the film will decrease if too much short-chain PBAT is added.

[0048] Table 3

[0049] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 2 23.2 484 Example 3 22.1 423

[0050] Embodiment 4:

[0051] Same as Example 1, but the PBAT pellets were boiled at 95°C for 48h. After the PBAT pellets were dried, the MFR was tested using a melt flow rate (MFR) meter and was 350g / 10min (190°C, 2.16kg). The results are shown in Table 4 below. This shows that when the amount of short-chain PBAT added remains unchanged, the longer the PBAT pellets are boiled, the more obvious the modification effect of the short-chain PBAT on the calcium powder is, and the higher the tensile strength of the film is.

[0052] Table 4

[0053] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 1 21.2 396 Example 4 23.7 472

[0054] Embodiment 5:

[0055] Same as Example 4, but the addition amount of short-chain PBAT was increased to 5% of the total material mass, and the addition amount of ordinary PBAT was 15% of the total material mass. The results are shown in Table 5 below. It shows that increasing the amount of short-chain PBAT has a more obvious modification effect on calcium powder.

[0056] Table 5

[0057] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 4 23.7 472 Example 5 24.9 468

[0058] Embodiment 6:

[0059] Same as Example 4, but the addition amount of short-chain PBAT was increased to 10% of the total material mass, and the addition amount of ordinary PBAT was 10% of the total material mass. The results are shown in Table 6 below. It shows that the increase in the tensile strength of the film will decrease when too much short-chain PBAT is added.

[0060] Table 6

[0061] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 5 24.9 468 Example 6 22.3 428

[0062] Embodiment 7:

[0063] Same as Example 5, but the masterbatch and the common PBAT pellets were adjusted to be mixed evenly at a mass ratio of 1:1.286 and 1:1, and the required film was obtained by film blowing by a film blowing machine and the mechanical properties were tested. The results are shown in Table 7 below. It shows that increasing the proportion of CaCO3 / PBAT high-filler masterbatch will reduce the tensile strength of the prepared film.

[0064] Table 6

[0065] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Example 5 24.9 468 Film made from masterbatch and common PBAT pellets at a mass ratio of 1:1.286 21.9 402 Film made from masterbatch and ordinary PBAT pellets in a mass ratio of 1:1 19.8 386

[0066] Comparative Example 2:

[0067] Same as Example 5, but short-chain PBAT was not added. Instead, 0.6wt% stearic acid (which has anchoring, modification and activation effects on calcium powder) was added to the material system. The amount of ordinary PBAT pellets added was 19.4% of the total material addition amount. The CaCO3 / PBAT high-filling masterbatch prepared with calcium powder modified with stearic acid was obtained. After dilution and film blowing, the CaCO3 / PBAT film was obtained, and its mechanical properties were tested. The results are shown in Table 7 below. It shows that the modification effect of short-chain PBAT on calcium powder is more obvious than that of stearic acid, and the longitudinal tensile strength of the film prepared by adding the masterbatch of short-chain PBAT is significantly higher.

[0068] Table 7

[0069] <![CDATA[CaCO3 / PBAT film]]> Longitudinal tensile strength (MPa) Elongation at break (%) Comparative Example 1 18.7 412 Comparative Example 2 21.4 408 Example 5 24.9 468

[0070] Comparative Example 3:

[0071] Same as Example 5, but short-chain PBAT was not added. Instead, 1.6wt% OPE wax (Honeywell, 629A) was added to the material system. The amount of ordinary PBAT pellets added was 18.4% of the total material addition amount. The CaCO3 / PBAT high-filling masterbatch prepared with calcium powder modified with OPE wax was obtained. After dilution and film blowing, the CaCO3 / PBAT film was obtained, and its mechanical properties were tested, and the taste of different films was compared. The results are shown in Table 8 below, indicating that the addition of short-chain PBAT does have a better modification effect on calcium powder than the addition of OPE wax, and the tensile strength of the film is improved. In addition, the absence of OPE wax makes the product less odorous, and is more suitable for the production of PBAT films that are directly or indirectly in contact with food.

[0072] Table 8

[0073] <![CDATA[CaCO3 / PBAT thin film]]> Tensile strength(MPa) Elongation at break (%) Odor size Comparative Example 1 18.7 412 Almost no Example 5 24.9 468 Almost no Comparative Example 3 22.8 451 Has a more obvious odor

Claims

1. A method for preparing CaCO3 / PBAT high-filling masterbatch by in-situ modification of calcium carbonate powder with short-chain PBAT, characterized in that: The method comprises the following steps: (1) Boil ordinary PBAT pellets at 85-98°C for 36-72h, stirring continuously during the boiling process to ensure uniform heating; (2) draining the boiled PBAT pellets obtained in step (1), and drying them with forced air at 60-70° C. for 12-15 h to obtain dried PBAT particles; (3) The dried PBAT particles obtained in step (2) are mixed with calcium carbonate powder and ordinary PBAT pellets, mixed by a high-speed mixer and extruded by a twin-screw extruder to obtain a CaCO3 / PBAT high-filler masterbatch; wherein the mass percentages of the dried PBAT particles and the calcium carbonate powder are 2.5-10% and 60-80%, respectively, based on the total mass of the dried PBAT particles, the calcium carbonate powder and the ordinary PBAT pellets being 100%.

2. The method according to claim 1, characterized in that: Taking the total mass of the dried PBAT particles, calcium carbonate powder and common PBAT granules as 100%, the mass percentage of the dried PBAT particles is 5%.

3. The method according to claim 1, characterized in that: In step (1), the boiling time is 36-48 hours.

4. The method according to claim 1, characterized in that: In step (3), the mixing conditions in the high-speed mixer are: 10-15 min, 80-90° C., 800-1000 r / min.

5. The method according to claim 1, characterized in that: In step (3), the extrusion conditions of the twin-screw extruder are: 140-170° C., 300-400 r / min.

6. A CaCO3 / PBAT high-filling masterbatch prepared according to the preparation method of claim 1.

7. A PBAT film, characterized in that: The PBAT film is obtained by mixing common PBAT pellets and the CaCO3 / PBAT high-filler masterbatch according to claim 6 and blowing the mixture, and the mass ratio of the CaCO3 / PBAT high-filler masterbatch to the common PBAT pellets is 1:1-2.

8. The PBAT film according to claim 7, characterized in that: The mass ratio of the CaCO3 / PBAT high-filling masterbatch to the common PBAT pellets is 1:1.

667.

9. The PBAT film according to claim 7, characterized in that: The film blowing conditions are: 140-160°C, 5-10Hz, 6-12m / min.

Images