Biodegradable transparent film polyester opening master batch, its preparation method and application

Abstract

The application belongs to the technical field of polymer materials, and relates to a polyester opening master batch for biodegradable transparent film, and a preparation method and application thereof. The preparation method comprises the following steps: putting terephthalic acid, 1,3-cyclohexane diacid, 1,4-butanediol and a catalyst a into an esterification kettle 1 to perform esterification reaction 1; putting adipic acid, 1,4-butanediol, nano-silica suspension and a catalyst b into an esterification kettle 2 to perform esterification reaction 2; and putting the esterification reaction 1 product, the esterification reaction 2 product, a catalyst c and a stabilizer into a polycondensation kettle to sequentially perform pre-polycondensation reaction and final polycondensation reaction, so as to obtain the polyester opening master batch for biodegradable transparent film. The polyester opening master batch is applied to the preparation of biodegradable transparent film by being blended with PBAT and being blown into a film. The application can uniformly disperse nano-silica by adding the nano-silica in a specific way, and can reduce crystallinity by adding 1,3-cyclohexane diacid to improve the light transmittance of the film and reduce the haze.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and relates to a polyester opening master batch for biodegradable transparent film and a preparation method and application thereof. BACKGROUND

[0002] In the research and application field of biodegradable materials, biodegradable transparent film is concerned due to its environmental protection characteristics and wide application prospect. The film is mainly prepared by using PBAT, PLA and other biodegradable materials as raw materials through blending modification technology. In order to improve the performance of the film, a chain extender is usually added to enhance the compatibility and melt strength of the material, and an opening agent is also added to improve the smoothness and processing performance of the film.

[0003] However, the existing biodegradable transparent film preparation technology has some problems. On the one hand, when using an opening agent with organic components, the opening agent is easy to migrate to the surface of the film, resulting in a layer of foggy phenomenon on the surface of the film, thereby reducing the light transmittance and haze of the film and affecting the appearance quality and application effect of the product. On the other hand, the inorganic component opening agent, especially nano-silicon dioxide, although performs well in improving the smoothness of the film, but in the modification extrusion process, due to the large viscosity of the raw material, the nano-silicon dioxide is easy to agglomerate and is not uniformly dispersed, which also affects the light transmittance and haze of the film.

[0004] In order to solve these problems, researchers have conducted a lot of research and exploration. For example, patent CN115678214A proposes a high-stiffness degradable transparent functional master batch and its preparation method and application. The method prepares a master batch by blending and modifying high-mesh talc, aluminum silicate and low-molecular-weight polycaprolactone, and then cold-mixing and blowing the master batch with PBAT. However, this method improves the performance of the film to some extent, but still has some problems. For example, the organic component lubricant in the master batch will precipitate to the surface of the film, affecting the light transmittance and haze of the film; at the same time, the master batch contains a lot of powder, which is difficult to disperse uniformly, also affecting the overall performance of the film. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art and provide a polyester opening master batch for biodegradable transparent film and a preparation method and application thereof.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of a polyester opening master batch for biodegradable transparent film, comprising the following steps:

[0008] (a) Put terephthalic acid, 1,3-cyclohexane diacid, 1,4-butanediol and catalyst a into an esterification kettle 1 to perform esterification reaction 1;

[0009] The adipic acid, 1,4-butanediol, nano-silica suspension, and catalyst b are put into the esterification kettle 2 to perform esterification reaction 2;

[0010] The dispersion medium of the nano-silica suspension is 1,4-butanediol;

[0011] The molar ratio of acid to alcohol in the esterification kettle 1 is 1:1.5-2, the molar ratio of acid to alcohol (except the dispersion medium of the nano-silica suspension) in the esterification kettle 2 is 1:2-2.5, the temperature of the esterification reaction 1 is 210-230℃, and the temperature of the esterification reaction 2 is 170-200℃;

[0012] The alcohol is in excess in both the esterification kettle 1 and the esterification kettle 2, which aims to make the acid completely react, and the excess alcohol in the esterification reaction can be removed during vacuumizing; the reactivity of terephthalic acid is general, and the temperature of the esterification reaction 1 is thus set to shorten the reaction time; the reactivity of adipic acid is high, and the temperature of the esterification reaction 2 is thus set to avoid the occurrence of explosive polymerization at a too high temperature;

[0013] (b) putting the esterification reaction 1 product, the esterification reaction 2 product, catalyst c, and stabilizer into a polycondensation kettle to sequentially perform pre-polycondensation reaction and final polycondensation reaction, and obtaining a polyester opening master batch for biodegradable transparent film.

[0014] The application uses nano-silica as an opening agent, which has the advantages of not migrating and precipitating and being able to meet the requirements of food packaging materials; the nano-silica has a spherical structure and a high specific surface area, which is beneficial to the opening of the film and does not affect the printing on the surface of the film. In the application, the nano-silica is added to 1,4-butanediol before polymerization, and is added to the esterification kettle 2 after being dispersed into a nano-silica suspension by ultrasonic dispersion. On the one hand, the nano-silica is not easy to explode because the reaction temperature of the esterification kettle 2 is relatively low, and on the other hand, the addition amount of 1,4-butanediol in the esterification kettle 2 is relatively large compared with the esterification kettle 1, and the nano-silica can be further dispersed uniformly and agglomeration is reduced by heating and stirring.

[0015] The application adds 1,3-cyclohexanedicarboxylic acid in the esterification kettle 1, which can reduce the regularity of the molecular chain of the polyester opening master batch, thereby reducing the crystallinity thereof, making it a low-crystallinity or non-crystalline material, and meanwhile, the 1,3-cyclohexanedicarboxylic acid can hinder the crystallization of PBAT when the polyester opening master batch is blended with PBAT to blow a film, so that the overall crystallinity of the film is reduced, the light transmittance is improved, and the haze is reduced.

[0016] As a preferred technical solution:

[0017] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, the molar ratio of terephthalic acid to 1,3-cyclohexane diacid in esterification kettle 1 is 1:0.2-0.5, and the molar ratio of catalyst a to acid is 1:800-1500; the time of esterification reaction 1 is 2.5-4h, and the pressure is 50-80KPa.

[0018] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, the molar ratio of acid to nano-silicon dioxide in esterification kettle 2 is 1:0.12-0.15, the molar ratio of catalyst b to acid is 1:1000-2000, and the nano-silicon dioxide suspension is obtained by mixing nano-silicon dioxide with a molar ratio of 1:5-7 and 1,4-butanediol and then ultrasonic dispersion for 4-6h; the time of esterification reaction 2 is 2.5-4h, and the pressure is 50-80KPa.

[0019] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, the molar ratio of the total amount of 1,3-cyclohexane diacid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 is 1:1.2.

[0020] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, the molar ratio of the total amount of 1,3-cyclohexane diacid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 is 1:1.2.

[0021] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, the temperature of the pre-polycondensation reaction is 215-240℃, the time is 3-6h, and the pressure is 5-40KPa; the temperature of the final polycondensation reaction is 215-245℃, the time is 4-6h, and the pressure is 80-200Pa.

[0022] The preparation method of the polyester opening master batch for biodegradable transparent film as described above, catalyst a, catalyst b and catalyst c are each independently selected from one of tetrabutyl titanate and tetraethyl titanate, and the stabilizer is triphenyl phosphate or triethyl phosphate.

[0023] The application further provides the polyester opening master batch for biodegradable transparent film, which is prepared by the preparation method of the polyester opening master batch for biodegradable transparent film, contains terephthalic acid-1, 4-butanediol segments, 1, 3-cyclohexane acid-1, 4-butanediol segments and adipic acid-1, 4-butanediol segments in a molecular chain, has a melt index of 3.6-4.2 g / 10 min, a melting point of 100.52-112.7 ℃, an ash content of 1.86-2.36%, an L value of 75.4-83.9, an a value of-1.5-3.3, a b value of 4.2-7.9 and a crystallization enthalpy of 0.54-5.88 J / g.

[0024] The application further provides the application of the polyester opening master batch for biodegradable transparent film as described above, which is used for blending with PBAT to prepare biodegradable transparent film.

[0025] As a preferred technical scheme,

[0026] The application as described above has a PBAT content of 55-65 wt% in the biodegradable transparent film, a thickness of 30-31 μm, a light transmittance of 89.3-90.5, a haze of 13.4-14.4, good opening property, smooth film appearance, no precipitation, and a biodegradation rate of 94.8-97.4%.

[0027] When the prior art uses an opening agent and PBAT to prepare a film, the opening agent and the PBAT need to be granulated through a screw melt extrusion process, and then the obtained granules (chips) are used for film blowing processing. When the polyester opening master batch and the PBAT are used to prepare a film according to the application, the polyester opening master batch and the PBAT do not need to be granulated through a screw melt extrusion process, but can be directly mixed uniformly by a mixer and then used for film blowing processing, so that degradation caused by secondary processing can be avoided, and the service life of the product is affected. The biodegradable transparent film obtained by the application has a high light transmittance and a low haze, can meet the detection requirements of food film, can be biodegraded, is easy to process, and saves production cost.

[0028] In the polyester opening master batch, 1, 3-cyclohexane acid is introduced, so that the regularity of the molecular chain of the polyester opening master batch is reduced, the crystallinity of the polyester opening master batch is reduced, and the content of benzene rings in the polyester opening master batch is reduced, so that the biodegradable transparent film containing a certain amount of polyester opening master batch is more easily decomposed by microorganisms under composting conditions, and the biodegradation rate of the biodegradable transparent film is higher.

[0029] Advantages:

[0030] (1) The application uses nano-silicon dioxide as an opening agent, which has a spherical structure and a high specific surface area, is beneficial to film opening, and does not migrate and precipitate, thereby meeting the requirements of food packaging materials and ensuring use safety and performance stability.

[0031] (2) In the application, the nano-silicon dioxide is dissolved in a 1,4-butanediol solution to form a nano-silicon dioxide suspension by ultrasonic dispersion before polymerization, and then added to the esterification kettle 2, so that the nano-silicon dioxide can be uniformly dispersed and agglomeration is reduced by the relatively low reaction temperature of the esterification kettle 2 and the relatively large amount of 1,4-butanediol added and heating and stirring, thereby ensuring the uniformity of the material performance.

[0032] (3) The application adds 1,3-cyclohexane diacid to the esterification kettle 1, so that the regularity of the molecular chain of the polyester opening master batch is reduced, the crystallinity is reduced to become a low-crystallinity or non-crystalline material, and the crystallization of PBAT is hindered when the polyester opening master batch is blended with PBAT to blow a film, so that the overall crystallinity of the film is reduced, the light transmittance is improved, the haze is reduced, and the optical performance and quality of the film are improved.

[0033] (4) The biodegradable transparent film of the application is more easily decomposed by microorganisms under composting conditions, and the biodegradation rate of the biodegradable transparent film is higher. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 DSC curve of PBAT of Example 3;

[0035] Figure 2 DSC curve of polyester opening master batch of Example 3. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope of the claims attached to the application.

[0037] The following are the test methods of the relevant performance indicators in each example and comparative example:

[0038] Melt index: detected according to the standard specified in GB / T 3682-2000 “Determination of the mass flow rate and volume flow rate of the melt of thermoplastics”; wherein the weight of the weight is 2.16 kg, and the temperature is set to 190℃.

[0039] Melting point, crystallization enthalpy: detected according to GB / T 19466.3-2004 "Differential Scanning Calorimetry (DSC) - Part 3: Determination of Melting and Crystallization Temperatures and Enthalpies"; wherein the starting temperature is 0℃, the ending temperature is 200℃, and the heating rate is 10℃ / min (the test conditions of PBAT and polyester opening master batch are the same).

[0040] Ash content: detected according to GB / T 9345.1-2008 "Determination of the Ash Content of Plastics - Part 1: General Method" standard, using direct combustion method (A method); wherein the ignition temperature is 850±50℃.

[0041] L value, a value, b value: detected according to 5.5.2 Method B (dry method) in GB / T 14190-2017 "Test Methods for Fiber Grade Poly(ethylene terephthalate) (PET) Chips", using CIE 1976 L*a*b color system.

[0042] Haze, light transmittance: detected according to GB T 2410-2008 "Determination of Transmittance and Haze of Transparent Plastics".

[0043] Opening property: the prepared film after blowing is rubbed by hand, and it can be easily rubbed open, indicating that the opening property is good, and it cannot be rubbed open, indicating that the opening property is poor.

[0044] Film appearance: the prepared film after blowing is touched by hand, and the film is rubbed lightly to feel smooth or rough; whether there are white crystal-like fine particles on the surface of the film is observed, if there are, it indicates that the agglomerated nano-silicon dioxide is precipitated from the film (precipitation), and the dispersibility is poor, if not, it indicates that no agglomerated nano-silicon dioxide is precipitated from the film (no precipitation), and the dispersibility is good.

[0045] Biodegradation rate: detected according to GB / T 19277.1-2011 "Determination of the ultimate aerobic biodegradability of materials under controlled composting conditions - Method by measuring the released carbon dioxide - Part 1: General method".

[0046] Example 1

[0047] A preparation method of a biodegradable transparent film, the specific steps are as follows:

[0048] (1) Preparation of raw materials;

[0049] Nano-silicon dioxide: average particle size is 30nm, whiteness is 98.8%;

[0050] Substance A, substance B and substance C: all are 1,4-butanediol;

[0051] Terephthalic acid;

[0052] 1,3-cyclohexanedicarboxylic acid;

[0053] Catalyst a, catalyst b: both are tetrabutyl titanate;

[0054] Adipic acid;

[0055] Catalyst c: tetraethyl titanate;

[0056] Stabilizer: triphenyl phosphate;

[0057] PBAT: manufacturer is Kanghui New Material Technology Co., Ltd., and the brand is KHB21AP11;

[0058] (2) Preparation of nano-silica suspension;

[0059] The nano-silica and the substance A in a molar ratio of 1:5 were mixed and ultrasonically dispersed for 4 h to obtain the nano-silica suspension;

[0060] (3) Preparation of polyester opening master batch;

[0061] (3.1) Terephthalic acid, 1,3-cyclohexanedicarboxylic acid, substance B, and catalyst a were put into esterification kettle 1, and esterification reaction was carried out at a temperature of 210 ℃ and a pressure of 50 KPa for 2.5 h to obtain product 1, while adipic acid, substance C, nano-silica suspension, and catalyst b were put into esterification kettle 2, and esterification reaction was carried out at a temperature of 170 ℃ and a pressure of 50 KPa for 2.5 h to obtain product 2;

[0062] In the esterification kettle 1, the molar ratio of acid to substance B was 1:1.5, the molar ratio of terephthalic acid to 1,3-cyclohexanedicarboxylic acid was 1:0.2, and the molar ratio of catalyst a to acid was 1:800; in the esterification kettle 2, the molar ratio of acid to substance C was 1:2, the molar ratio of acid to nano-silica was 1:0.12, and the molar ratio of catalyst b to acid was 1:1000; the ratio of the total molar amount of 1,3-cyclohexanedicarboxylic acid and terephthalic acid in the esterification kettle 1 to the molar amount of adipic acid in the esterification kettle 2 was 1:1.2;

[0063] (3.2) Product 1, product 2, catalyst c, and stabilizer were put into the polycondensation kettle, and then pre-polycondensation reaction was carried out at a temperature of 215 ℃ and a pressure of 5 KPa for 3 h, and then final polycondensation reaction was carried out at a temperature of 215 ℃ and a pressure of 80 Pa for 4 h to obtain the polyester opening master batch; wherein the molar ratio of catalyst c to the total molar amount of acid in the esterification kettle 1 and the esterification kettle 2 was 1:3600, and the molar ratio of stabilizer to the total molar amount of acid in the esterification kettle 1 and the esterification kettle 2 was 1:3400;

[0064] The prepared polyester opening master batch had a melt index of 3.6 g / 10 min, a melting point of 112.7 ℃, an ash content of 1.86%, an L value of 83.9, an a value of -1.5, a b value of 4.2, and a crystallization enthalpy of 5.88 J / g.

[0065] (4) preparing a biodegradable transparent film;

[0066] The polyester opening master batch is blended with PBAT to blow a film, and a biodegradable transparent film is obtained; wherein the related process parameters of the film blowing are as follows: the first extrusion temperature is 140℃, the second extrusion temperature is 145℃, the third extrusion temperature is 145℃, the corner temperature is 145℃, the die temperature is 145℃, the fan frequency is 35HZ, and the traction motor frequency is 11HZ.

[0067] The content of PBAT in the finally prepared biodegradable transparent film is 55wt%; the thickness of the biodegradable transparent film is 30μm, the light transmittance is 89.8%, the haze is 13.7%, the opening property is good, the film appearance is smooth and no precipitation, and the biodegradation rate is 94.8%.

[0068] Example 2

[0069] A preparation method of a biodegradable transparent film, and the specific steps are as follows:

[0070] (1) preparation of raw materials;

[0071] Nano-silicon dioxide: the average particle size is 30nm, and the whiteness is 98.8%;

[0072] Substance A, substance B and substance C: all are 1,4-butanediol;

[0073] Terephthalic acid;

[0074] 1,3-cyclohexane diacid;

[0075] Catalyst a and catalyst b: both are tetrabutyl titanate;

[0076] Adipic acid;

[0077] Catalyst c: tetraethyl titanate;

[0078] Stabilizer: triethyl phosphate;

[0079] PBAT: the manufacturer is Kanghui New Material Technology Co., Ltd., and the brand is KHB21AP11;

[0080] (2) preparation of nano-silicon dioxide suspension;

[0081] Nano-silicon dioxide with a molar ratio of 1:7 is mixed with substance A and ultrasonically dispersed for 6h to obtain a nano-silicon dioxide suspension;

[0082] (3) preparation of polyester opening master batch;

[0083] (3.1) Put terephthalic acid, 1,3-cyclohexanedicarboxylic acid, substance B, catalyst a into esterification kettle 1, and carry out esterification reaction at temperature 230℃, pressure 80KPa for 4h to obtain product 1, while put adipic acid, substance C, nano-silica suspension, catalyst b into esterification kettle 2, and carry out esterification reaction at temperature 200℃, pressure 80KPa for 4h to obtain product 2;

[0084] In esterification kettle 1, the molar ratio of acid to substance B is 1:2, the molar ratio of terephthalic acid to 1,3-cyclohexanedicarboxylic acid is 1:0.35, and the molar ratio of catalyst a to acid is 1:1500; in esterification kettle 2, the molar ratio of acid to substance C is 1:2.5, the molar ratio of acid to nano-silica is 1:0.15, and the molar ratio of catalyst b to acid is 1:2000; the ratio of the total molar amount of 1,3-cyclohexanedicarboxylic acid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 is 1:1.2;

[0085] (3.2) After putting product 1, product 2, catalyst c, and stabilizer into the polycondensation kettle, first carry out pre-polycondensation reaction at temperature 240℃, pressure 40KPa for 6h, and then carry out final polycondensation reaction at temperature 245℃, pressure 200Pa for 6h to obtain polyester opening master batch; wherein the ratio of the molar amount of catalyst c to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:6300, and the ratio of the molar amount of stabilizer to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:6000;

[0086] The prepared polyester opening master batch has a melt index of 4.2g / 10min, a melting point of 100.52℃, an ash content of 2.32%, an L value of 75.4, an a value of 3.3, a b value of 7.9, and a crystallization enthalpy of 0.54J / g;

[0087] (4) Preparation of biodegradable transparent film;

[0088] Blow film the polyester opening master batch and PBAT to obtain biodegradable transparent film; wherein the related process parameters of blow film are: first extrusion temperature 140℃, second extrusion temperature 145℃, third extrusion temperature 145℃, corner temperature 145℃, die temperature 145℃, air fan frequency 35HZ, and traction motor frequency 11HZ.

[0089] The final prepared biodegradable transparent film has a PBAT content of 65wt%; the biodegradable transparent film has a thickness of 31μm, a light transmittance of 90.5%, a haze of 14.2%, good opening property, smooth film appearance, no precipitation, and a biodegradation rate of 97.4%.

[0090] Example 3

[0091] A preparation method of a biodegradable transparent film, the specific steps are as follows:

[0092] (1) Preparation of raw materials;

[0093] Nano-silica: average particle size 30 nm, whiteness 98.8%;

[0094] Substance A, substance B and substance C: all are 1,4-butanediol;

[0095] Terephthalic acid;

[0096] 1,3-cyclohexane diacid;

[0097] Catalyst a and catalyst b: both are tetrabutyl titanate;

[0098] Adipic acid;

[0099] Catalyst c: tetraethyl titanate;

[0100] Stabilizer: triphenyl phosphate;

[0101] PBAT: manufacturer is Kanghui New Material Technology Co., Ltd., brand is KHB21AP11, DSC curve is as shown in Figure 1 ;

[0102] (2) Preparation of nano-silica suspension;

[0103] Nano-silica and substance A with a molar ratio of 1:6 were mixed and ultrasonically dispersed for 5h to obtain a nano-silica suspension;

[0104] (3) Preparation of polyester opening master batch;

[0105] (3.1) Terephthalic acid, 1,3-cyclohexane diacid, substance B and catalyst a were put into esterification kettle 1, and esterification reaction was carried out at a temperature of 220℃ and a pressure of 65KPa for 3.25h to obtain product 1, while adipic acid, substance C, nano-silica suspension and catalyst b were put into esterification kettle 2, and esterification reaction was carried out at a temperature of 185℃ and a pressure of 65KPa for 3.25h to obtain product 2;

[0106] In esterification kettle 1, the molar ratio of acid to substance B was 1:1.75, the molar ratio of terephthalic acid to 1,3-cyclohexane diacid was 1:0.28, and the molar ratio of catalyst a to acid was 1:1200; in esterification kettle 2, the molar ratio of acid to substance C was 1:2.25, the molar ratio of acid to nano-silica was 1:0.135, and the molar ratio of catalyst b to acid was 1:1500; the ratio of the total molar amount of 1,3-cyclohexane diacid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 was 1:1.2;

[0107] (3.2) After putting product 1, product 2, catalyst c, stabilizer into the polycondensation reactor, pre-polycondensation is carried out at a temperature of 227℃ and a pressure of 22.5KPa for 4.5h, and then final polycondensation is carried out at a temperature of 230℃ and a pressure of 140Pa for 5h to obtain polyester opening master batch; wherein the ratio of the molar amount of catalyst c to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:4950, and the ratio of the molar amount of stabilizer to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:4700;

[0108] The melting index of the prepared polyester opening master batch is 3.8g / 10min, the melting point is 104.78℃ (DSC curve as shown in Figure 2 ), the ash content is 2.1%, the L value is 78.6, the a value is 1.3, the b value is 6.5, and the crystallization enthalpy is 2.34J / g;

[0109] (4) Preparation of biodegradable transparent film;

[0110] The polyester opening master batch is blended with PBAT to blow film, and a biodegradable transparent film is obtained; wherein the related process parameters of the blending blow film are as follows: the first extrusion temperature is 140℃, the second extrusion temperature is 145℃, the third extrusion temperature is 145℃, the corner temperature is 145℃, the die temperature is 145℃, the die temperature is 145℃, the fan frequency is 35HZ, and the traction motor frequency is 11HZ.

[0111] The content of PBAT in the finally prepared biodegradable transparent film is 60wt%; the thickness of the biodegradable transparent film is 30μm, the light transmittance is 90.1%, the haze is 13.5%, the opening property is good, the film appearance is smooth and no precipitation, and the biodegradation rate is 96.7%.

[0112] Comparative Example 1

[0113] A method for preparing a film, which is basically the same as Example 3, except that the nano-silica and substance A are directly put into esterification kettle 2 without mixing and ultrasonic dispersion in advance.

[0114] The light transmittance of the finally prepared film is 83.5%, the haze is 23.5%, the film appearance is rough and white crystal-like fine particles are precipitated.

[0115] Compared with Example 3, the light transmittance, haze and film appearance of the film of Comparative Example 1 are obviously deteriorated. This is because the nano-silica in Comparative Example 1 is not ultrasonically dispersed into a suspension, but directly added into esterification kettle 2. During the subsequent reaction process of esterification kettle 2, the dispersion effect of the nano-silica is poor, resulting in nano-silica particles that are not completely and uniformly dispersed and agglomerated. After film blowing, part of the particles are precipitated and gathered on the surface of the film, resulting in rough film appearance. When light irradiates the film, the particles gathered on the surface of the film hinder the transmission of the transmitted light, and the amount of scattered light increases, resulting in a decrease in light transmittance and an increase in film haze.

[0116] Comparative Example 2

[0117] A film preparation method is basically the same as that of Example 3, except that the nano-silica suspension is not added into esterification kettle 2, but into esterification kettle 1 (the added amount of moles is the same as that of Example 3).

[0118] The light transmittance of the finally prepared film is 84.6%, the haze is 22.7%, and the film appearance is rough with white crystal-like fine particles precipitated.

[0119] Compared with Example 3, the light transmittance, haze and film appearance of the film of Comparative Example 2 are obviously deteriorated. This is because the nano-silica suspension is added into esterification kettle 1, and the addition amount of 1,4-butanediol is lower than that of esterification kettle 2, making it difficult for the nano-silica to be well dispersed and easy for the nano-silica particles to agglomerate. At the same time, the reaction temperature of esterification kettle 1 is 220°C, which is relatively high and easy to cause explosive agglomeration, making it more difficult for the nano-silica to be uniformly dispersed in the polymer during polymerization. After film blowing, part of the particles are precipitated and gathered on the surface of the film, resulting in rough film appearance. When light irradiates the film, the particles gathered on the surface of the film hinder the transmission of the transmitted light, and the amount of scattered light increases, resulting in a decrease in light transmittance and an increase in film haze.

[0120] Comparative Example 3

[0121] A film preparation method is basically the same as that of Example 3, except that 1,3-cyclohexanedicarboxylic acid is replaced by an equal amount of terephthalic acid.

[0122] The light transmittance of the finally prepared film is 87.5%, and the haze is 18.3%.

[0123] Compared with Example 3, the light transmittance and haze of the film of Comparative Example 3 are obviously deteriorated. This is because after 1,3-cyclohexanedicarboxylic acid is replaced by terephthalic acid, the component that can reduce the molecular chain regularity of the polyester opening master batch is lacking, which makes the crystallinity of the polyester opening master batch relatively increase. Crystallization causes more scattering of light in the film, so the light transmittance of the film decreases and the haze increases.

[0124] Example 4

[0125] A method for preparing a biodegradable transparent film, the specific steps are as follows:

[0126] (1) Preparation of raw materials;

[0127] Nano-silica: average particle size of 30 nm, whiteness of 98.8%;

[0128] Substance A, substance B and substance C: all are 1,4-butanediol;

[0129] Terephthalic acid;

[0130] 1,3-cyclohexane diacid;

[0131] Catalyst a and catalyst b: both are tetrabutyl titanate;

[0132] Adipic acid;

[0133] Catalyst c: tetraethyl titanate;

[0134] Stabilizer: triphenyl phosphate;

[0135] PBAT: manufacturer is Kanghui New Material Technology Co., Ltd., brand is KHB21AP11;

[0136] (2) Preparation of nano-silica suspension;

[0137] Nano-silica and substance A with a molar ratio of 1:6 were mixed and ultrasonically dispersed for 5h to obtain a nano-silica suspension;

[0138] (3) Preparation of polyester opening master batch;

[0139] (3.1) Terephthalic acid, 1,3-cyclohexane diacid, substance B and catalyst a were put into esterification kettle 1, and esterification reaction was carried out at a temperature of 220℃ and a pressure of 65KPa for 3.25h to obtain product 1, while adipic acid, substance C, nano-silica suspension and catalyst b were put into esterification kettle 2, and esterification reaction was carried out at a temperature of 185℃ and a pressure of 65KPa for 3.25h to obtain product 2;

[0140] In esterification kettle 1, the molar ratio of acid to substance B was 1:1.75, the molar ratio of terephthalic acid to 1,3-cyclohexane diacid was 1:0.35, and the molar ratio of catalyst a to acid was 1:1200; in esterification kettle 2, the molar ratio of acid to substance C was 1:2.25, the molar ratio of acid to nano-silica was 1:0.135, and the molar ratio of catalyst b to acid was 1:1500; the ratio of the total molar amount of 1,3-cyclohexane diacid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 was 1:1.2;

[0141] (3.2) After putting product 1, product 2, catalyst c, stabilizer into the polycondensation reactor, pre-polycondensation is carried out at a temperature of 227℃ and a pressure of 22.5KPa for 4.5h, and then final polycondensation is carried out at a temperature of 230℃ and a pressure of 140Pa for 5h to obtain polyester opening master batch; wherein the ratio of the molar amount of catalyst c to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:4950, and the ratio of the molar amount of stabilizer to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 is 1:4700;

[0142] The melting index of the prepared polyester opening master batch is 3.9g / 10min, the melting point is 101.55℃, the ash content is 2.15%, the L value is 78.4, the a value is 1.2, the b value is 6.4, and the crystallization enthalpy is 0.68J / g;

[0143] (4) Preparation of biodegradable transparent film;

[0144] The polyester opening master batch is blended with PBAT to blow film, and a biodegradable transparent film is obtained; wherein the related process parameters of the blending blow film are as follows: the first extrusion temperature is 140℃, the second extrusion temperature is 145℃, the third extrusion temperature is 145℃, the corner temperature is 145℃, the die temperature is 145℃, the fan frequency is 35HZ, and the traction motor frequency is 11HZ.

[0145] The content of PBAT in the finally prepared biodegradable transparent film is 60wt%; the thickness of the biodegradable transparent film is 31μm, the light transmittance is 89.3%, the haze is 13.4%, the opening property is good, the film appearance is smooth and no precipitation, and the biodegradation rate is 96.5%.

[0146] Example 5

[0147] A preparation method of a biodegradable transparent film, the specific steps are as follows:

[0148] (1) Preparation of raw materials;

[0149] Nanosilica: average particle size of 30nm, whiteness of 98.8%;

[0150] Substance A, substance B and substance C: all are 1,4-butanediol;

[0151] Terephthalic acid;

[0152] 1,3-cyclohexane diacid;

[0153] Catalyst a and catalyst b: both are tetrabutyl titanate;

[0154] Adipic acid;

[0155] Catalyst c: tetraethyl titanate;

[0156] Stabilizer: triphenyl phosphate;

[0157] PBAT: KHB21AP11, manufacturer: Kanghui New Material Technology Co., Ltd.

[0158] (2) Preparation of nano-silica suspension;

[0159] Nano-silica and substance A were mixed at a molar ratio of 1:6 and ultrasonic dispersion was carried out for 5h to obtain a nano-silica suspension;

[0160] (3) Preparation of polyester opening master batch;

[0161] (3.1) Terephthalic acid, 1,3-cyclohexanedicarboxylic acid, substance B, and catalyst a were put into esterification kettle 1, and esterification reaction was carried out at a temperature of 220℃ and a pressure of 65KPa for 3.25h to obtain product 1, while adipic acid, substance C, nano-silica suspension, and catalyst b were put into esterification kettle 2, and esterification reaction was carried out at a temperature of 185℃ and a pressure of 65KPa for 3.25h to obtain product 2;

[0162] In esterification kettle 1, the molar ratio of acid to substance B was 1:1.75, the molar ratio of terephthalic acid to 1,3-cyclohexanedicarboxylic acid was 1:0.28, and the molar ratio of catalyst a to acid was 1:1200; in esterification kettle 2, the molar ratio of acid to substance C was 1:2.25, the molar ratio of acid to nano-silica was 1:0.15, and the molar ratio of catalyst b to acid was 1:1500; the ratio of the total molar amount of 1,3-cyclohexanedicarboxylic acid and terephthalic acid in esterification kettle 1 to the molar amount of adipic acid in esterification kettle 2 was 1:1.2;

[0163] (3.2) Product 1, product 2, catalyst c, and stabilizer were put into the polycondensation kettle, and pre-polycondensation reaction was carried out at a temperature of 227℃ and a pressure of 22.5KPa for 4.5h, and then final polycondensation reaction was carried out at a temperature of 230℃ and a pressure of 140Pa for 5h to obtain polyester opening master batch; wherein the molar ratio of catalyst c to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 was 1:4950, and the molar ratio of stabilizer to the total molar amount of acid in esterification kettle 1 and esterification kettle 2 was 1:4700;

[0164] The prepared polyester opening master batch had a melt index of 4.1g / 10min, a melting point of 105.24℃, an ash content of 2.36%, an L value of 78.8, an a value of 1.3, a b value of 6.6, and a crystallization enthalpy of 2.84J / g;

[0165] (4) Preparation of biodegradable transparent film;

[0166] The polyester opening master batch is blended with PBAT to blow a film, and a biodegradable transparent film is obtained; wherein the related process parameters of the blown film are as follows: the first extrusion temperature is 140 DEG C, the second extrusion temperature is 145 DEG C, the third extrusion temperature is 145 DEG C, the corner temperature is 145 DEG C, the die body temperature is 145 DEG C, the die head temperature is 145 DEG C, the fan frequency is 35 HZ, and the traction motor frequency is 11 HZ.

[0167] The content of PBAT in the finally prepared biodegradable transparent film is 60 wt%; the thickness of the biodegradable transparent film is 30 μm, the light transmittance is 89.9%, the haze is 14.4%, the opening property is good, the film appearance is smooth and no precipitation, and the biodegradation rate is 96.3%.

Claims

1. A method for producing a polyester opening master batch for a biodegradable transparent film, characterized by, The method comprises the following steps: (a) putting terephthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-butanediol, and a first catalyst into an esterification kettle 1 to perform an esterification reaction 1; putting adipic acid, 1,4-butanediol, a nano-silica suspension, and a second catalyst into an esterification kettle 2 to perform an esterification reaction 2; The dispersion medium of the nano-silica suspension is 1,4-butanediol; The molar ratio of acid to alcohol in the esterification kettle 1 is 1:1.5-2, and the molar ratio of acid to alcohol (except the dispersion medium of the nano-silica suspension) in the esterification kettle 2 is 1:2-2.5; the temperature of the esterification reaction 1 is 210-230℃, and the temperature of the esterification reaction 2 is 170-200℃; (b) putting the product of the esterification reaction 1, the product of the esterification reaction 2, a third catalyst, and a stabilizer into a polycondensation kettle to perform a pre-polycondensation reaction and a final polycondensation reaction in sequence, thereby obtaining a biodegradable transparent film polyester opening master batch.

2. The method for preparing a polyester open-face masterbatch for biodegradable transparent films according to claim 1, characterized in that, In the esterification kettle 1, the molar ratio of terephthalic acid to 1,3-cyclohexanedicarboxylic acid is 1:0.2-0.5, and the molar ratio of the first catalyst to acid is 1:800-1500; the esterification reaction 1 is performed for 2.5-4h at a pressure of 50-80kPa.

3. The method for preparing a polyester open-face masterbatch for biodegradable transparent films according to claim 1, characterized in that, In the esterification kettle 2, the molar ratio of acid to nano-silica is 1:0.12-0.15, and the molar ratio of the second catalyst to acid is 1:1000-2000; the nano-silica suspension is obtained by mixing nano-silica and 1,4-butanediol at a molar ratio of 1:5-7 and then ultrasonic dispersion for 4-6h; the esterification reaction 2 is performed for 2.5-4h at a pressure of 50-80kPa.

4. The method for preparing a polyester open-face masterbatch for biodegradable transparent films according to claim 1, characterized in that, The ratio of the total molar amount of 1,3-cyclohexanedicarboxylic acid and terephthalic acid in the esterification kettle 1 to the molar amount of adipic acid in the esterification kettle 2 is 1:1.

2.

5. The method of claim 1, wherein the polyester opening master batch for biodegradable transparent film is prepared by the following steps: (1) mixing and kneading the polyester resin, the biodegradable resin, the additive and the antioxidant to obtain a mixture; (2) extruding the mixture to obtain a pellet; and (3) drying the pellet. The molar amount of the third catalyst in the polycondensation kettle to the total molar amount of acid in the esterification kettle 1 and the esterification kettle 2 is 1:3600-6300, and the molar amount of the stabilizer in the polycondensation kettle to the total molar amount of acid in the esterification kettle 1 and the esterification kettle 2 is 1:3400-6000.

6. The method of claim 1, wherein the polyester opening master batch for biodegradable transparent film is prepared by the following steps: (1) mixing and kneading the polyester resin, the biodegradable resin, the additive and the antioxidant to obtain a mixture; (2) extruding the mixture to obtain a pellet; and (3) drying the pellet. The pre-polycondensation reaction is performed at a temperature of 215-240℃ for 3-6h at a pressure of 5-40kPa, and the final polycondensation reaction is performed at a temperature of 215-245℃ for 4-6h at a pressure of 80-200Pa.

7. The method of claim 1, wherein the polyester opening master batch for biodegradable transparent film is prepared by the following steps: (1) mixing and kneading the polyester resin, the biodegradable resin, the additive and the antioxidant to obtain a mixture; (2) extruding the mixture to obtain a pellet; and (3) drying the pellet. The first catalyst, the second catalyst, and the third catalyst are each independently selected from one of tetrabutyl titanate and tetraethyl titanate, and the stabilizer is triphenyl phosphate or triethyl phosphate.

8. A polyester opening master batch for biodegradable transparent film, characterized by, The biodegradable transparent film polyester opening master batch is prepared by the method described in any one of claims 1-7; the melt index of the biodegradable transparent film polyester opening master batch is 3.6-4.2g / 10min, the melting point is 100.52-112.7℃, the ash content is 1.86-2.36%, the L value is 75.4-83.9, the a value is -1.5-3.3, the b value is 4.2-7.9, and the crystallization enthalpy is 0.54-5.88J / g.

9. Use of the polyester opening master batch for biodegradable transparent film according to claim 8, characterized in that, The biodegradable transparent film is prepared by blending with PBAT.

10. Use according to claim 9, characterized in that, The content of PBAT in the biodegradable transparent film is 55-65 wt%; the thickness of the biodegradable transparent film is 30-31 mu m, the light transmittance is 89.3-90.5%, the haze is 13.4-14.4%, the film appearance is smooth, no precipitation, and the biodegradation rate is 94.8-97.4%.

Images