A calcium carbonate composition, calcium carbonate masterbatch, and a preparation method and application thereof

Abstract

The application discloses a calcium carbonate composition, a calcium carbonate master batch and a preparation method and application thereof, and belongs to the technical field of high polymer materials. The calcium carbonate composition comprises the following components in parts by weight: polybutylene adipate terephthalate 10-40 parts, biodegradable polyester 1-5 parts, calcium carbonate 60-90 parts and processing aid 0-5 parts. The surface of the calcium carbonate is coated with an activating agent, and the activating agent is stearic acid. The mass content of the stearic acid accounts for 1.1-1.8% of the mass of the calcium carbonate. The biodegradable polyester comprises units derived from at least one dicarboxylic acid and at least one aliphatic diol. The aliphatic diacid is an aliphatic dicarboxylic acid with a main chain of at least 7 carbon atoms. In the calcium carbonate composition, by controlling the specific type of biodegradable polyester and the amount of activating agent stearic acid in the calcium carbonate, the generation of broken strips in the production process can be reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a calcium carbonate composition, calcium carbonate masterbatch, its preparation method and application. Background Technology

[0002] Plastic films or bags are commonly used in packaging and transportation industries, requiring certain levels of mechanical properties such as tensile strength, tear resistance, and impact resistance. Furthermore, these mechanical properties must maintain a certain level of strength even under prolonged exposure to humid and hot environments.

[0003] Biodegradable plastic film bags are typically made from polybutylene terephthalate (PBAT) material through blown film production. Adding calcium carbonate filler masterbatch to PBAT material and cold-blending it can improve the mechanical properties of the plastic film and reduce costs.

[0004] Biodegradable calcium carbonate filler masterbatch is generally obtained by co-extruding calcium carbonate and polybutylene adipate (PEG) through a mill. Calcium carbonate masterbatch with a high calcium carbonate content is called high-filler calcium carbonate masterbatch.

[0005] In the production process of high-filled calcium carbonate masterbatch extrusion, drawing, and pelletizing using a twin-screw extruder, the excessively high proportion of calcium carbonate powder in the masterbatch easily leads to uneven dispersion, resulting in inconsistent particle size and strength. This causes breakage in the pellets during the extrusion process. Re-extrusion is necessary, disrupting production continuity. Furthermore, the waste material generated from these undetected breakages results in significant material waste.

[0006] Currently, most solutions to masterbatch breakage are addressed through equipment adjustments. For example, existing technology describes an underwater cooling device for color masterbatch processing. This device uses a conveyor belt to transport the material strips into a water tank, ensuring sufficient contact between the belt and the strips and significantly reducing breakage. Furthermore, the inclined design of the conveyor belt facilitates the removal and collection of the strips. Another existing patent describes a method for preparing low-melting-point weather-resistant additive masterbatch. This method uses an underwater die-cutting method to obtain low-melting-point weather-resistant additive masterbatch from the blended melt, solving the problem of broken or non-formed strips when using string pelletizing for low-melting-point weather-resistant additives. The particles obtained from underwater die-cutting are regular in shape and uniform in size.

[0007] However, existing technologies have not addressed the technical problem of reducing the number of times the calcium carbonate composition used to prepare calcium carbonate masterbatch is prone to breakage during production by improving the composition of the calcium carbonate composition itself. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing calcium carbonate compositions used to prepare calcium carbonate masterbatch, which are prone to breakage during the production process, and to provide a calcium carbonate composition that is not prone to breakage during the production process of calcium carbonate masterbatch.

[0009] Another object of the present invention is to provide a method for preparing calcium carbonate masterbatch.

[0010] Another object of the present invention is to provide an application of calcium carbonate masterbatch in the field of biodegradability.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution:

[0012] A calcium carbonate composition comprising the following components: 10-40 parts of polybutylene adipate terephthalate, 1-5 parts of other biodegradable polyesters, 60-90 parts of calcium carbonate, and 0-5 parts of processing aids.

[0013] The surface of the calcium carbonate is coated with an activator, which is stearic acid, and the mass content of stearic acid accounts for 1.1%-1.8% of the mass of calcium carbonate.

[0014] The other biodegradable polyesters comprise units derived from at least one dicarboxylic acid and at least one aliphatic diol;

[0015] The dicarboxylic acid comprises the following components:

[0016] a1) Based on the total amount of a1) and a2), 50-60 mol% of aliphatic dicarboxylic acids or their ester derivatives, or mixtures thereof;

[0017] a2) Based on the total amount of a1) and a2), 40-50 mol% of terephthalic acid or its ester derivatives, or mixtures thereof, wherein the total molar percentage of components a1) to a2) is 100%;

[0018] The aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid with a main chain of at least 7 carbon atoms.

[0019] In the calcium carbonate composition of the present invention, by controlling the use of other biodegradable polyesters of a specific type, the melt flowability of the calcium carbonate composition can be significantly improved. At the same time, by controlling the amount of stearic acid, an activator in calcium carbonate, the dispersion of calcium carbonate is promoted, and the melt strength of the melt is more uniform, thereby reducing the occurrence of broken strips during the production process.

[0020] This invention modifies the composition of calcium carbonate compositions without requiring equipment modifications, the addition of non-degradable components, or expensive additives, thereby effectively reducing the breakage phenomenon of calcium carbonate compositions used to prepare calcium carbonate masterbatches during the production process.

[0021] In practical applications, calcium carbonate compositions can be used with polybutylene adipate terephthalate (PAT) blown film to prepare plastic film materials.

[0022] In the calcium carbonate composition of the present invention, if the molar fraction of polybutylene terephthalate segment in other biodegradable polyesters is too low, the hydrolysis resistance of the plastic film material will be greatly reduced, and it will not meet the application requirements.

[0023] In the calcium carbonate composition of this invention, if the molar fraction of polybutylene terephthalate segment in other biodegradable polyesters is too high, the basic mechanical properties of the plastic film material will be significantly reduced, and it will not meet the application requirements.

[0024] The test method for the mass content of stearic acid, an activator, in calcium carbonate is as follows:

[0025] Weigh 10 g of calcium carbonate sample and place it in a 400 ml beaker. Add 1 mol / L hydrochloric acid and heat on an electric furnace until the sample is completely dissolved. Remove from the furnace and cool with water to room temperature. Filter the solution through a triangular funnel using defatted cotton (place a small wad of loose defatted cotton at the center of the funnel, with a glass bead on the cotton). Wash with cold distilled water until no chloride ions are present. Test with silver nitrate solution. Transfer the glass bead and defatted cotton to an Erlenmeyer flask. Wash the walls of the sample-dissolving beaker and the triangular funnel with ethanol to remove residual stearic acid, and combine the ethanol with the rinse water in the Erlenmeyer flask. At an appropriate temperature, add a few drops of phenolphthalein indicator and titrate with NaOH standard solution.

[0026] Representation and calculation of results:

[0027] Stearic acid content % = (V1 - V2) × C × 0.2843 / G × 100%

[0028] In the formula:

[0029] V1—Number of milliliters of NaOH standard solution consumed by the sample;

[0030] V2—Number of milliliters of NaOH standard solution consumed in the blank test;

[0031] C—NaOH solution concentration (mol / L)

[0032] G — Mass of the sample (g)

[0033] 0.2843 — the number of grams of stearic acid equivalent to one milliliter of sodium hydroxide with a concentration of C=1mol / L.

[0034] Preferably, the dicarboxylic acid comprises the following components:

[0035] a1) Based on the total amount of a1) and a2), 44-46 mol% of aliphatic dicarboxylic acids or their ester derivatives, or mixtures thereof;

[0036] a2) Based on the total amount of a1) and a2), 44 to 46 mol% of terephthalic acid or its ester derivatives, or mixtures thereof, wherein the total molar percentage of components a1) to a2) is 100%.

[0037] Preferably, the D50 particle size of calcium carbonate is 3~5μm.

[0038] Preferably, the stearic acid content is 1.2%-1.5% of the mass of calcium carbonate.

[0039] More preferably, the mass content of stearic acid is 1.2%-1.4% of the mass of calcium carbonate.

[0040] In the calcium carbonate composition of the present invention, polybutylene adipate terephthalate has the structure shown in formula (I):

[0041]

[0042] p+q=1, where p is 0.40-0.50.

[0043] More preferably, in polybutylene adipate terephthalate, p is 0.44-0.46. That is, the molar fraction of polybutylene terephthalate segment in polybutylene adipate terephthalate is 0.44-0.46.

[0044] Preferably, the aliphatic diacid is an aliphatic dicarboxylic acid with a main chain of 7 to 13 carbon atoms.

[0045] Preferably, the aliphatic dicarboxylic acid is one or more of heptanoic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, or dodecanoic acid.

[0046] More preferably, the aliphatic diacid is an aliphatic dicarboxylic acid with 8 to 10 carbon atoms as the main chain.

[0047] In this invention, the polybutylene adipate terephthalate and other biodegradable polyesters can be commercially available or homemade. Methods for making other biodegradable polyesters include, but are not limited to, the following:

[0048] S1. Esterification of terephthalic acid and butanediol yields ester A1; esterification of aliphatic dicarboxylic acid and butanediol yields ester A2.

[0049] S2. The condensation reaction of esterified A1 and esterified A2 yields the other biodegradable polyesters.

[0050] Preferably, in this invention, the preparation method of the other biodegradable polyester includes the following steps:

[0051] S1. Terephthalic acid and 1,4-butanediol are added to an esterification reactor at a molar ratio of 1:(1.4-1.6), and a catalyst of (0.8-1.5)% of the total mass of the raw materials is added. The reaction is carried out at a temperature of 220-250℃ and a pressure of 40-60KPa for 1-2.5h to obtain esterified product A1.

[0052] Aliphatic dicarboxylic acid and 1,4-butanediol were added to an esterification reactor at a molar ratio of 1:(1.5-1.7) and reacted for 1-3.5 h at a temperature of 200-220℃ and a pressure of 40-60 kPa to obtain esterified product A2.

[0053] S2. Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of (30-60):(70-40) and mixed. The mixture is reacted for 1-5 hours at a temperature of 220-260℃ and a pressure of 4-6KPa to obtain a prepolymer. The prepolymer is then polymerized for another 1-5 hours at a temperature of 220-260℃ and a pressure of 100-120Pa to obtain other biodegradable polyesters.

[0054] In the other methods for preparing biodegradable polyesters described in this invention, in step S1, the catalyst can be n-butyl titanate.

[0055] Since uneven dispersion is more likely to occur in highly filled calcium carbonate masterbatch, leading to breakage, the compositions of the present invention are particularly suitable for preparing highly filled calcium carbonate masterbatch.

[0056] Preferably, the calcium carbonate composition contains ≥50% calcium carbonate by weight.

[0057] More preferably, the calcium carbonate composition contains ≥75% calcium carbonate by weight.

[0058] More preferably, the calcium carbonate composition contains 75-85% calcium carbonate by weight.

[0059] Preferably, the melt flow rate of the polybutylene adipate terephthalate is 4-12 g / 10 min, the test conditions are 190℃, 2.16 kg, and the test standard is ISO 1133-1:2022.

[0060] More preferably, the melt flow rate of polybutylene adipate terephthalate is 4-10 g / 10 min, the test conditions are 190 °C, 2.16 kg, and the test standard is ISO 1133-1:2022.

[0061] More preferably, the melt flow rate of polybutylene adipate terephthalate is 6-10 g / 10 min, the test conditions are 190 °C, 2.16 kg, and the test standard is ISO 1133-1:2022.

[0062] Preferably, the melt flow rate of the other biodegradable polyester is 4-12 g / 10 min, the test conditions are 190 °C, 2.16 kg, and the test standard is ISO 1133-1:2022.

[0063] More preferably, the melt flow rate of the other biodegradable polyester is 6-10 g / 10 min, the test conditions are 190 °C, 2.16 kg, and the test standard is ISO 1133-1:2022.

[0064] The melt flow rates of the other biodegradable polyesters are similar to those of the polybutylene adipate terephthalate, which is beneficial for achieving processing consistency.

[0065] Preferably, the processing aid is one or more of an opening agent, a slip agent, or a white oil.

[0066] Optionally, the opening agent is one or more of erucamide, oleamide, or EBS.

[0067] Optionally, the slip agent is one or more of Fischer-Tropsch wax, paraffin wax, or polyethylene wax.

[0068] The calcium carbonate composition of the present invention is prepared by melting and mixing the raw materials.

[0069] The present invention also protects calcium carbonate masterbatch prepared from any of the calcium carbonate compositions described in any one of the claims.

[0070] This invention also protects a method for preparing calcium carbonate masterbatch according to any one of the above claims, comprising the following steps: adding a melt-blended calcium carbonate composition to a twin-screw extruder, and obtaining calcium carbonate masterbatch after extrusion, stranding, and pelletizing. The extrusion temperature is 140℃-240℃.

[0071] This invention also protects the use of the calcium carbonate masterbatch described in any of the above claims in the preparation of membranes and bags.

[0072] For example, the application of the calcium carbonate masterbatch in the preparation of garbage bags.

[0073] Compared with the prior art, the beneficial effects of the present invention are:

[0074] This invention discloses a calcium carbonate composition that, by controlling the amount of other biodegradable polyesters of a specific type and the amount of stearic acid, an activator in calcium carbonate, can significantly improve the melt flowability of the calcium carbonate composition, thereby promoting the dispersion of calcium carbonate and making the melt strength more uniform, thus reducing the occurrence of broken strips during the production process. Detailed Implementation

[0075] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0076] The activation degree is the percentage of the mass of stearic acid activator coating the surface of calcium carbonate to the mass of calcium carbonate.

[0077] Polybutylene adipate terephthalate 1, with a melt flow rate of 10 g / 10 min; the molar fraction of polybutylene adipate terephthalate segment in polybutylene adipate terephthalate 1 is 0.45, prepared in-house, and the preparation method is as follows:

[0078] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0079] 2) Adipic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 2.5 h at a temperature of 200℃ and a pressure of 40 kPa to obtain esterified product A2;

[0080] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted at 240℃ and 4KPa for 2.5h to obtain a prepolymer. The prepolymer is then further polymerized at 240℃ and 120Pa for 2.5h to obtain polybutylene adipate terephthalate 1.

[0081] Polybutylene adipate terephthalate 2, with a melt flow rate of 4 g / 10 min; the molar fraction of polybutylene adipate terephthalate in polybutylene adipate terephthalate 2 is 0.45, prepared in-house, and the preparation method is as follows:

[0082] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0083] 2) Adipic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted at 200℃ and 40KPa for 3.5h to obtain esterified product A2;

[0084] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted at 240℃ and 4KPa for 3.5h to obtain a prepolymer. The prepolymer is then further polymerized at 240℃ and 120Pa for 2.5h to obtain polybutylene adipate terephthalate 2.

[0085] Other biodegradable polyester 1, polybutylene terephthalate, melt flow rate of 10 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 1 is 0.45, prepared in-house. Preparation method is as follows:

[0086] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 1h to obtain esterified product A1.

[0087] 2) Add pimelic acid and 1,4-butanediol to the esterification reactor at a molar ratio of 1:1.67 and react for 1 hour at a temperature of 200℃ and a pressure of 40 kPa to obtain esterified product A2.

[0088] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and reacted for 1 hour at a temperature of 240℃ and a pressure of 4KPa to obtain a prepolymer. Then, the prepolymer is polymerized for another 1 hour at a temperature of 240℃ and a pressure of 120Pa to obtain other biodegradable polyester 1.

[0089] Other biodegradable polyester 2, polybutylene terephthalate, melt flow rate of 10 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 2 is 0.45, prepared in-house. Preparation method is as follows:

[0090] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 250℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0091] 2) Add octanediic acid and 1,4-butanediol to the esterification reactor at a molar ratio of 1:1.67, and react for 2.5 h at a temperature of 220℃ and a pressure of 40 kPa to obtain esterified product A2;

[0092] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and reacted for 2.5 h at a temperature of 250℃ and a pressure of 4 kPa to obtain a prepolymer. Then, the prepolymer is polymerized for another 2.5 h at a temperature of 250℃ and a pressure of 120 Pa to obtain other biodegradable polyester 2.

[0093] Other biodegradable polyester 3, polybutylene terephthalate, has a melt flow rate of 10 g / 10 min; the molar fraction of the polybutylene terephthalate segment in other biodegradable polyester 3 is 0.45, prepared in-house. The preparation method is as follows:

[0094] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 220℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0095] 2) Azelaic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 2.5 h at a temperature of 200℃ and a pressure of 40 kPa to obtain esterified product A2;

[0096] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted at 220°C and 4 kPa for 2.5 h to obtain a prepolymer. The prepolymer is then polymerized at 220°C and 120 Pa for another 2.5 h to obtain other biodegradable polyesters 3.

[0097] Other biodegradable polyester 4, polybutylene terephthalate sebate, PBSeT, melt flow rate of 10 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 4 is 0.45, prepared in-house, preparation method as follows:

[0098] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 220℃ and a pressure of 60KPa for 2.5h to obtain esterified product A1.

[0099] 2) Sebacic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted at 220℃ and 60KPa for 2.5h to obtain esterified product A2;

[0100] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted at a temperature of 260℃ and a pressure of 6KPa for 2.5h to obtain a prepolymer. The prepolymer is then polymerized at a temperature of 240℃ and a pressure of 100Pa for another 2.5h to obtain other biodegradable polyesters 4.

[0101] Other biodegradable polyester 5, polybutylene terephthalate (PET), melt flow rate of 10 g / 10 min; the molar fraction of PET segment in other biodegradable polyester 5 is 0.45, prepared in-house. Preparation method is as follows:

[0102] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0103] 2) Dodecanoic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 3 hours at a temperature of 200℃ and a pressure of 40KPa to obtain esterified product A2.

[0104] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and reacted for 3 hours at a temperature of 240℃ and a pressure of 4KPa to obtain a prepolymer. Then, the prepolymer is polymerized for another 3 hours at a temperature of 240℃ and a pressure of 120Pa to obtain other biodegradable polyesters 5.

[0105] Other biodegradable polyester 6, polybutylene terephthalate, has a melt flow rate of 4 g / 10 min; the molar fraction of the polybutylene terephthalate segment in other biodegradable polyester 6 is 0.45, prepared in-house. The preparation method is as follows:

[0106] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 250℃ and a pressure of 50KPa for 2 hours to obtain esterified product A1.

[0107] 2) Succinic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted at 200℃ and 40KPa for 3.5h to obtain esterified product A2;

[0108] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and reacted for 2.5 h at a temperature of 240℃ and a pressure of 4 kPa to obtain a prepolymer. Then, the prepolymer is polymerized for another 3.5 h at a temperature of 250℃ and a pressure of 120 Pa to obtain other biodegradable polyesters 6.

[0109] Other biodegradable polyester 7, polybutylene terephthalate sebate, PBSeT, melt flow rate of 8 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 7 is 0.4, prepared in-house. Preparation method is as follows:

[0110] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 220℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0111] 2) Sebacic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 3 hours at a temperature of 200℃ and a pressure of 40KPa to obtain esterified product A2.

[0112] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 40:60 and mixed. The mixture is reacted for 3 hours at a temperature of 240℃ and a pressure of 4KPa to obtain a prepolymer. The prepolymer is then further polymerized for 3 hours at a temperature of 240℃ and a pressure of 120Pa to obtain other biodegradable polyesters 7.

[0113] Other biodegradable polyester 8, polybutylene terephthalate sebate, PBSeT, melt flow rate of 6 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 8 is 0.5, prepared in-house. Preparation method is as follows:

[0114] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0115] 2) Sebacic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 3 hours at a temperature of 200℃ and a pressure of 40KPa to obtain esterified product A2.

[0116] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 50:50 and mixed. The mixture is reacted at 240°C and 4 kPa for 4 hours to obtain a prepolymer. The prepolymer is then polymerized at 240°C and 120 Pa for another 4 hours to obtain other biodegradable polyesters 8.

[0117] Other biodegradable polyester 9, polybutylene terephthalate sebate, PBSeT, melt flow rate of 4 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 9 is 0.45, prepared in-house. Preparation method is as follows:

[0118] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0119] 2) Sebacic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 3 hours at a temperature of 200℃ and a pressure of 40KPa to obtain esterified product A2.

[0120] 3) Two esters, A1 and A2, are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted for 5 hours at a temperature of 250°C and a pressure of 4 kPa to obtain a prepolymer. The prepolymer is then further polymerized for 5 hours at a temperature of 250°C and a pressure of 120 Pa to obtain other biodegradable polyesters 9.

[0121] Other biodegradable polyester 10, polybutylene terephthalate sebate, PBSeT, melt flow rate of 12 g / 10 min; the molar fraction of polybutylene terephthalate in other biodegradable polyester 10 is 0.45, prepared in-house. Preparation method is as follows:

[0122] 1) Terephthalic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.5, and 1% of the total mass of the raw materials was added as catalyst n-butyl titanate. The reaction was carried out at a temperature of 240℃ and a pressure of 40KPa for 2.5h to obtain esterified product A1.

[0123] 2) Sebacic acid and 1,4-butanediol were added to the esterification reactor at a molar ratio of 1:1.67 and reacted for 3 hours at a temperature of 200℃ and a pressure of 40KPa to obtain esterified product A2.

[0124] 3) The two esters A1 and A2 are continuously fed into a mixer at a molar ratio of 45:55 and mixed. The mixture is reacted for 1 hour at a temperature of 240℃ and a pressure of 4KPa to obtain a prepolymer. The prepolymer is then polymerized for another 1 hour at a temperature of 240℃ and a pressure of 120Pa to obtain other biodegradable polyester 10.

[0125] Unactivated calcium carbonate 1, manufactured by Lianzhou Xinrong, brand name LG-515.

[0126] Calcium carbonate 2, with an activation degree of 1.0%, is prepared as follows: Unactivated calcium carbonate LG-515 is dried at 100-110℃ for 1 hour and then added to a high-speed mixer. While maintaining a temperature not lower than 80℃ and continuously stirring, stearic acid (1.0% of the mass of the unactivated calcium carbonate) is added, followed by high-speed vigorous stirring for another 30 minutes. The mass content of stearic acid in calcium carbonate 2 is 1.0%.

[0127] Calcium carbonate 3, with an activation degree of 1.2%, is prepared as follows: Unactivated calcium carbonate LG-515 is dried at 100-110℃ for 1 hour and then added to a high-speed mixer. While maintaining a temperature not lower than 80℃ and continuously stirring, stearic acid (1.2% of the mass of the unactivated calcium carbonate) is added, followed by high-speed vigorous stirring for another 30 minutes. The mass content of stearic acid in calcium carbonate 3 is 1.2%.

[0128] Calcium carbonate 4, with an activation degree of 1.5%, is prepared as follows: Unactivated calcium carbonate LG-515 is dried at 100-110℃ for 1 hour and then added to a high-speed mixer. While maintaining a temperature not lower than 80℃ and continuously stirring, stearic acid (1.5% of the mass of the unactivated calcium carbonate) is added, followed by high-speed vigorous stirring for another 30 minutes. The mass content of stearic acid in calcium carbonate 4 is 1.5%.

[0129] Calcium carbonate 5, with an activation degree of 2.0%, is prepared as follows: Unactivated calcium carbonate LG-515 is dried at 100-110℃ for 1 hour and then added to a high-speed mixer. While maintaining a temperature not lower than 80℃ and continuously stirring, stearic acid (2% of the mass of the unactivated calcium carbonate) is added, followed by high-speed vigorous stirring for another 30 minutes. The mass content of stearic acid in calcium carbonate 5 is 2.0%.

[0130] Calcium carbonate 6, with an activation degree of 1.4%, is prepared as follows: Unactivated calcium carbonate LG-515 is dried at 100–110°C for 1 hour and then placed in a high-speed mixer. While maintaining a temperature not lower than 80°C, 1.4% (by mass) of silane coupling agent KH-550 is uniformly sprayed onto the unactivated calcium carbonate, followed by high-speed vigorous stirring for 30 minutes. The mass content of the silane coupling agent in calcium carbonate 6 is 1.4%.

[0131] The opening agent, erucamide, is commercially available, and the same one was used in the parallel examples and comparative examples.

[0132] The slip agent, a Fischer-Tropsch wax, is commercially available, and the same type was used in the parallel examples and comparative examples.

[0133] White oil, commercially available, and the same type was used in the parallel examples and comparative examples.

[0134] Examples 1-13

[0135] A calcium carbonate composition, by weight, comprises the following components:

[0136] Polybutylene adipate terephthalate, other biodegradable polyesters, calcium carbonate, processing aids, the processing aids being opening agents, slip agents and white oil, the weight ratio of opening agents, slip agents and white oil being 1:1:0.02.

[0137] The specific content of each component is shown in Table 1 below.

[0138] Table 1. Composition of calcium carbonate compositions in each embodiment (by weight parts)

[0139]

[0140] Continued from Table 1

[0141]

[0142] The specific method for preparing calcium carbonate masterbatch from the compositions of Examples 1-13 above is as follows:

[0143] The components are added to a twin-screw extruder, and after melt blending and extrusion, calcium carbonate masterbatch is obtained, with the extrusion temperature being 140℃-240℃.

[0144] Comparative Examples 1-7

[0145] A calcium carbonate composition, by weight, comprises the following components:

[0146] Polybutylene adipate terephthalate, biodegradable polyester, calcium carbonate, processing aids, the processing aids being opening agent, slip agent and white oil, the weight ratio of opening agent, slip agent and white oil being 1:1:0.02.

[0147] The specific content of each component is shown in Table 2 below.

[0148] Table 2. Composition of calcium carbonate compositions in each comparative example (parts by weight)

[0149]

[0150] The preparation methods for the calcium carbonate compositions of Comparative Examples 1-7 are the same as those for Examples 1-13, and will not be repeated here.

[0151] Result detection

[0152] The calcium carbonate masterbatches of the above embodiments and comparative examples were subjected to relevant performance tests during the preparation process:

[0153] Filter screen pressure difference: Test conditions: Pump inlet pressure set to 7 MPa, temperature 220℃, filter screen mesh size 320 mesh, pressure difference is the filter screen pressure difference between 20 min and 0 min. The lower the value, the better the dispersion of calcium carbonate.

[0154] The main components of the equipment are: a single screw extruder, a melt pump, a filter screen, and a die. Material is melted and extruded through the screw, and the system's dynamic control ensures a stable material pressure before the melt pump. The melt pump allows the material to be pumped forward uniformly and stably. Between the melt pump and the die is a filter screen and a pressure sensor. When the material is well dispersed, it can pass through the filter screen normally. Since the material pressure before the melt pump is stable, the pressure sensor before the screen should also be stable. When the material is poorly dispersed, large particles are gradually intercepted by the filter screen, forming a filter cake. In this case, the pressure before the screen will gradually increase. The increasing trend of the pressure curve is used to judge the material's dispersion performance.

[0155] Number of strand breaks: A 75D twin-screw extruder was used, with the processing temperature set at 180 ℃, the screw speed at 260 rpm, and the feed rate at 600 kg / h. The strands were drawn and pelletized, and the number of strand breaks was recorded within 12 hours.

[0156] The calcium carbonate compositions of each embodiment and comparative example were subjected to the following performance tests, and the specific steps are as follows:

[0157] The calcium carbonate compositions of each example and comparative example were compounded with PBAT (model KB100) produced by Kingfa Biotechnology at a mass ratio of 1:1 and plastic film products were prepared by blown film extrusion using a 50mm diameter single-screw blown film extruder. The die diameter was 75mm, the temperature was set at 135℃, the extrusion frequency was 16Hz, the traction was 22Hz, the film thickness was 0.03mm, and the film width was 385mm. The following tests were then conducted:

[0158] (1) Test the dart impact strength of the product according to ISO 7765-1-1988;

[0159] (2) Hydrolysis resistance: Each product was placed in a constant temperature and humidity chamber at 60% relative humidity and 60℃ for 15 days for damp heat testing. Then, the performance of each product was tested according to the same method as in (1), and the performance retention rate before and after standing was calculated. The higher the retention rate, the better the hydrolysis resistance.

[0160] The specific detection results for each embodiment are shown in Table 3 below:

[0161] Table 3

[0162]

[0163] The specific test results for each comparative example are shown in Table 4 below:

[0164] Table 4

[0165]

[0166] The results above show that during the preparation of the calcium carbonate masterbatch of the present invention, the number of breakages in 12 hours is less than 2 or even none, and the filter screen pressure difference is less than 5 MPa. The dart impact strength can reach 252-313 g, and the dart impact strength retention rate in the damp heat test can reach 60-70%.

[0167] As can be seen from Examples and Comparative Example 1, in other biodegradable polyesters, the aliphatic diacid has 4 carbon atoms and the number of breaks in 12 hours is 3, which does not meet the requirements.

[0168] As can be seen from Examples 2 and 3, unactivated calcium carbonate or calcium carbonate with excessively low activation resulted in 4 and 2 breakages in 12 hours, respectively, and excessively high pressure differential on the filter screen. This may be because the stearic acid content is too low, preventing the calcium carbonate from dispersing effectively.

[0169] As can be seen from Examples and Comparative Example 4, the activation of calcium carbonate was too high, with two breakages in 12 hours, and the filter screen pressure difference was too high. This may be because the presence of carboxyl groups can accelerate the degradation of biodegradable plastics, and the high stearic acid content leads to excessively rapid degradation of the biodegradable plastics in the extruder, resulting in insufficient melt strength.

[0170] As can be seen from Examples and Comparative Example 5, the activation of calcium carbonate with other substances does not achieve the lubricating effect of stearic acid. This may be because the dispersing effect of calcium carbonate is limited in this highly filled system.

[0171] As can be seen from Examples 1 and 6, without the addition of other biodegradable polyesters, the number of yarn breaks in 12 hours was 3. This does not meet the requirements.

[0172] As can be seen from Examples 1 and 7, the excessive use of other biodegradable polyesters resulted in two breakages within 12 hours, and the filter pressure differential was too high. These conditions failed to meet the requirements.

[0173] As can be seen from Examples 1 and 5-8, in other biodegradable polyesters, the aliphatic diacid has 8-10 carbon atoms, resulting in fewer breakages and lower filter pressure differentials, and the prepared products have superior mechanical properties.

[0174] As can be seen from Examples 1 and 10-11, the molar fraction of polybutylene terephthalate in other biodegradable polyesters 1 is between 0.44 and 0.46, resulting in fewer breakages, lower filter pressure differentials, and superior mechanical properties in the prepared products.

[0175] As can be seen from Examples 1 and 12-13, other biodegradable polyesters have a melt flow rate of 6-10 g / 10 min, fewer breakages, lower filter screen pressure differentials, and the resulting products have superior mechanical properties.

[0176] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A calcium carbonate composition, characterized in that, It includes the following components: 10-40 parts of polybutylene adipate terephthalate, 1-5 parts of other biodegradable polyesters, 60-90 parts of calcium carbonate, and 0-5 parts of processing aids; The surface of the calcium carbonate is coated with an activator, which is stearic acid, and the mass content of stearic acid accounts for 1.1%-1.8% of the mass of calcium carbonate. The other biodegradable polyesters comprise units derived from at least one dicarboxylic acid and butanediol; The dicarboxylic acid comprises the following components: a1) Based on the total amount of a1) and a2), 50-60 mol% of aliphatic dicarboxylic acids or their ester derivatives, or mixtures thereof; a2) Based on the total amount of a1) and a2), 40-50 mol% of terephthalic acid or its ester derivatives, or mixtures thereof, wherein the total molar percentage of components a1) to a2) is 100%; The aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid with a main chain of at least 7 carbon atoms.

2. The calcium carbonate composition according to claim 1, characterized in that, The aliphatic dicarboxylic acid is one or more of heptanoic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, or dodecanoic acid.

3. The calcium carbonate composition according to claim 1, characterized in that, The preparation methods of the other biodegradable polyesters include the following steps: S1. Esterification of terephthalic acid and butanediol yields ester A1; esterification of aliphatic dicarboxylic acid and butanediol yields ester A2. S2. The condensation reaction of esterified A1 and esterified A2 yields the other biodegradable polyesters.

4. The calcium carbonate composition according to claim 1, characterized in that, The melt flow rate of the polybutylene adipate terephthalate was 4-12 g / 10 min, the test conditions were 190℃ and 2.16 kg, and the test standard was ISO 1133-1:2022.

5. The calcium carbonate composition according to claim 4, characterized in that, The melt flow rate of polybutylene adipate terephthalate was 6-10 g / 10 min, the test conditions were 190℃, 2.16 kg, and the test standard was ISO 1133-1:2022.

6. The calcium carbonate composition according to claim 1 or 4, characterized in that, The melt flow rate of the other biodegradable polyesters is 4-12 g / 10 min, the test conditions are 190 °C, 2.16 kg, and the test standard is ISO 1133-1:2022.

7. The calcium carbonate composition according to claim 1, characterized in that, The processing aid is one or more of an opening agent, a slip agent, or a white oil.

8. Calcium carbonate masterbatch prepared from the calcium carbonate composition according to any one of claims 1 to 7.

9. The method for preparing the calcium carbonate masterbatch according to claim 8, characterized in that, Includes the following steps: The melt-blended calcium carbonate composition of any one of claims 1 to 7 is added to a twin-screw extruder, and after extrusion, stranding, and pelletizing, calcium carbonate masterbatch is obtained.

10. The application of the calcium carbonate masterbatch according to claim 8 in the preparation of membranes and bags.

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