Modified hydrotalcite as well as preparation method, master batch, film and application thereof

Abstract

The invention provides a modified hydrotalcite, a preparation method thereof, a master batch, a film and application. The modified hydrotalcite comprises hydrotalcite and an amphiphilic compound located on the surface of the hydrotalcite, the hydrophilic end of the amphiphilic compound is combined with the surface of the hydrotalcite, and the hydrophobic end of the amphiphilic compound is far away from the surface of the hydrotalcite. The amphiphilic compound has a hydrophilic end and a hydrophobic end, the hydrophilic end and hydroxyl on the surface of the hydrotalcite generate bonding action to form a covalent bond, the amphiphilic compound can stably exist on the surface of the hydrotalcite, the hydrophobic end of the amphiphilic compound is far away from the surface of the hydrotalcite, and the hydrophobicity of the surface of the hydrotalcite can be regulated and controlled; therefore, the compatibility and dispersity between the hydrotalcite and the polymer can be improved, the infrared absorption performance of a film formed by the hydrotalcite and the polymer can be improved, and the thermal insulation performance of the film can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin films, in particular to a modified hydrotalcite, a preparation method thereof, a master batch, a thin film and application. BACKGROUND

[0002] With the continuous progress of agricultural production technology, agricultural plastic film has become an important guarantee in agricultural production. Polymers such as polyethylene (PE) and polypropylene (PP) are widely used in the field of agricultural film due to their advantages such as not easy to stain dust, no dripping phenomenon, light specific gravity, and simple production process. However, the infrared transmittance of polymer agricultural film itself is as high as 65% or more, and the heat preservation performance is poor. Therefore, organic or inorganic additives are often added to improve the heat preservation performance of polymer agricultural film. Traditional inorganic materials such as talc, kaolin and montmorillonite have poor infrared absorption performance and large particle size, which affects the light transmittance. The heat preservation performance of the prepared heat preservation agricultural film is generally poor. Due to the poor compatibility and dispersibility of inorganic materials and polymer film, the mechanical properties are decreased, which seriously affects the actual use of agricultural film products and the increase of agricultural production. Therefore, developing new efficient inorganic infrared absorbers and improving their application performance in polymer agricultural film has become an important direction for the development of agricultural film industry.

[0003] Layered double hydroxide, also known as hydrotalcite, is a new type of layered functional material. Hydrotalcite has unique two-dimensional layered structure, exchangeable interlayer anions and adjustable layer composition, and has infrared absorption performance for infrared rays. It can be used as an infrared absorption material in polymers to improve the heat preservation performance. Studies have found that hydrotalcite has a wide range of infrared absorption (5-25 μm), and the infrared waveband of ground heat loss at night is mainly in the range of 7-11 μm. Therefore, how to control the composition and structure of hydrotalcite and the two-dimensional size and morphology to achieve selective absorption of infrared rays in this range has become an important research direction for industry researchers. At the same time, as an inorganic material, hydrotalcite has a large number of hydrophilic hydroxyl groups on its surface. Direct application in PE and other polymer agricultural films has poor compatibility and dispersibility, resulting in uneven dispersion, easy to produce bubbles due to surface adsorption of water, and seriously affecting the application of hydrotalcite in agricultural film. As a powder, hydrotalcite is difficult to use directly in downstream agricultural film production plants due to strict process requirements. Therefore, it is urgent to control the hydrophilic and hydrophobic properties of the surface of hydrotalcite, increase the compatibility with polymer agricultural film, and improve the addition method in the agricultural film to promote the dispersion and fully play the infrared absorption performance of hydrotalcite. SUMMARY

[0004] The main purpose of the present application is to provide a modified hydrotalcite, a preparation method thereof, a master batch, a film and an application, so as to solve the problem of poor visible light transmittance and infrared light absorption of agricultural films due to poor compatibility and dispersibility of hydrotalcite and polymers in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a modified hydrotalcite is provided, which comprises hydrotalcite and an amphiphilic compound on the surface of the hydrotalcite, the hydrophilic end of the amphiphilic compound is combined with the surface of the hydrotalcite, and the hydrophobic end is away from the surface of the hydrotalcite.

[0006] Further, the mass ratio of the hydrotalcite to the amphiphilic compound is 1:(0.02-0.15); and / or, the hydrotalcite has a two-dimensional layered structure, the ab plane particle size of the hydrotalcite is 0.1-10 μm, preferably 0.2-3.5 μm, and the stacking layer number of the hydrotalcite is 2-60 layers, preferably 5-40 layers.

[0007] Further, the chemical formula of the hydrotalcite is M 2+ 1-x M 3+ x (OH)2(A n- ) x / n ·mH2O; wherein, M 2+ is a divalent metal cation, M 3+ is a trivalent metal cation, A n- is an interlayer anion, x is the molar ratio of M 3+ / (M 2+ +M 3+ ), 0.2≤x≤0.4, 0≤m≤6; preferably, M 2+ is selected from any one or more of Mg 2+ , Zn 2+ and Ca 2+ ; and / or, M 3+ is selected from Al 3+ and / or Fe 3+ ; and / or, A n- is selected from any one or more of CO3 2- , SO4 2- , Cl - , NO 3- , PO4 3- , HPO4 2- , H2PO4 - , (2-hydroxyethyl)phosphonate ion, succinylphosphonate ion and phenylphosphonate ion.

[0008] Further, the amphiphilic compound is selected from any one or more of ester-based amphiphilic compounds and / or phosphoric acid-based amphiphilic compounds; preferably, the amphiphilic compound is selected from any one or more of hydroxyethyl methacrylate, 2-phenylethyl diethyl phosphate, 2,2-diethoxyethyl diethyl phosphate, tetramethyl ethylenediphosphonic acid and 1-hydroxybutyl diethyl phosphate; more preferably, the amphiphilic compound is a combination of hydroxyethyl methacrylate and tetramethyl ethylenediphosphonic acid, and the mass ratio of hydroxyethyl methacrylate to tetramethyl ethylenediphosphonic acid is 1:(1-2).

[0009] According to another aspect of the present application, there is provided a method for preparing the modified hydrotalcite as described above, which comprises: mixing the hydrotalcite, the amphiphilic compound and water to perform a modification reaction, thereby obtaining the modified hydrotalcite.

[0010] Further, the modification reaction is performed at a temperature of 40-160°C; and / or, the modification reaction is performed for a time period of 0.5-6h.

[0011] Further, the method for preparing the hydrotalcite comprises: performing a crystallization treatment on a divalent metal ion source, a trivalent metal ion source, an interlayer anion source, water and a growth-directing agent, thereby obtaining the hydrotalcite; the mass ratio of the total mass of the divalent metal ion source and the trivalent metal ion source to the mass of the growth-directing agent is (0.5-2.0):1; the crystallization treatment is performed at a temperature of 60-200°C for a time period of 0.5-36h.

[0012] Further, the growth-directing agent is selected from any one or more of alcohol compounds, amine compounds and quaternary ammonium salt compounds; preferably, the growth-directing agent is selected from any one or more of ethanol, ethylene glycol, hexamethylenetetramine and cetyltrimethylammonium bromide; further preferably, the growth-directing agent is a combination of ethylene glycol and hexamethylenetetramine, and the mass ratio of ethylene glycol to hexamethylenetetramine is 1:(0.2-0.8).

[0013] According to yet another aspect of the present application, there is provided a master batch comprising a polymer and an additive, the additive comprising the modified hydrotalcite as described above or prepared by the method as described above; preferably, the polymer is selected from polyethylene and / or polypropylene; preferably, the modified hydrotalcite has a weight content of 5-80% in the master batch.

[0014] According to yet another aspect of the present application, there is provided a film prepared by sequentially performing mixing and calendering on the master batch as described above and a polymer.

[0015] According to yet another aspect of the present application, there is provided the use of the film as described above as an agricultural film.

[0016] By the technical solution of the present application, the amphiphilic compound in the present application has a hydrophilic end and a hydrophobic end, the hydrophilic end forms a covalent bond with the hydroxyl group on the surface of the hydrotalcite, which helps the amphiphilic compound to stably exist on the surface of the hydrotalcite, and the hydrophobic end of the amphiphilic compound is away from the surface of the hydrotalcite, which helps to regulate the hydrophobicity of the surface of the hydrotalcite, thereby helping to improve the compatibility and dispersibility between the hydrotalcite and the polymer, thereby helping to improve the infrared absorption performance and visible light transmittance of the thin film formed by the hydrotalcite and the polymer, and compared with the unmodified hydrotalcite, more modified hydrotalcite can be added in the polymer, thereby helping to further improve the infrared absorption performance and visible light transmittance of the thin film formed by the hydrotalcite and the polymer, and further helping to improve the heat preservation performance and transparency of the thin film. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, and the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0018] Figure 1 An XRD diagram of the hydrotalcite in Example 1 of the present application is shown;

[0019] Figure 2 An SEM diagram of the hydrotalcite in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0021] It should be noted that the ab plane of the present application refers to a plane perpendicular to the thickness direction.

[0022] As analyzed in the background art of the present application, the poor compatibility and dispersibility between the hydrotalcite and the polymer in the prior art result in the poor visible light transmittance and infrared light absorption rate of the agricultural film, in order to solve the above problems, the present application provides a modified hydrotalcite, a preparation method, a master batch, a thin film and an application thereof.

[0023] In a typical embodiment of the present application, a modified hydrotalcite is provided, which comprises a hydrotalcite and an amphiphilic compound on the surface of the hydrotalcite, the hydrophilic end of the amphiphilic compound is combined with the surface of the hydrotalcite, and the hydrophobic end is away from the surface of the hydrotalcite.

[0024] The amphiphilic compound in the present application has a hydrophilic end and a hydrophobic end. The hydrophilic end forms a covalent bond with the hydroxyl group on the surface of the hydrotalcite, which helps the amphiphilic compound to stably exist on the surface of the hydrotalcite. The hydrophobic end of the amphiphilic compound is away from the surface of the hydrotalcite, which helps to regulate the hydrophobicity of the surface of the hydrotalcite, thereby improving the compatibility and dispersibility between the hydrotalcite and the polymer, and improving the infrared absorption performance and visible light transmittance of the thin film formed by the hydrotalcite and the polymer. Compared with the unmodified hydrotalcite, more modified hydrotalcite can be added to the polymer, thereby further improving the infrared absorption performance and visible light transmittance of the thin film formed by the hydrotalcite and the polymer, and further improving the heat preservation performance and transparency of the thin film.

[0025] In an embodiment of the present application, the mass ratio of the hydrotalcite to the amphiphilic compound is 1:(0.02-0.15); and / or, the hydrotalcite has a two-dimensional layered structure, the ab plane particle size of the hydrotalcite is 0.1-10 μm, preferably 0.2-3.5 μm, and the stacking layer number of the hydrotalcite is 2-60 layers, preferably 5-40 layers.

[0026] Controlling the mass ratio of the hydrotalcite to the amphiphilic compound in the above range helps to further improve the compatibility and dispersibility between the modified hydrotalcite and the polymer, thereby further improving the infrared light absorption performance and visible light transmittance of the thin film. Controlling the ab plane particle size of the hydrotalcite in the above range helps to improve the absorption of the hydrotalcite to the infrared light in the 1428-909 cm -1 band; and controlling the stacking layer number of the hydrotalcite in the above range helps to improve the continuous multi-stage absorption to the infrared light, thereby further improving the infrared light absorption performance of the hydrotalcite.

[0027] In order to further improve the infrared light absorption performance of the hydrotalcite, in an embodiment of the present application, the chemical formula of the hydrotalcite is M 2+ 1-x M 3+ x (OH)2(A n- ) x / n ·mH2O; wherein, M 2+ is a divalent metal cation, M 3+ is a trivalent metal cation, A n- is an interlayer anion, x is the molar ratio of M 3+ / (M 2+ +M 3+ ), 0.2≤x≤0.4, 0≤m≤6; preferably, M 2+ is selected from any one or more of Mg 2+ , Zn 2+ and Ca 2+ ; and / or, M3+ selected from Al 3+ and / or Fe 3+ ; and / or, A n- selected from CO3 2- , SO4 2- , Cl - , NO 3- , PO4 3- , HPO4 2- , H2PO4 - , (2-hydroxyethyl)phosphonate ion, succinylphosphonate ion and phenylphosphonate ion.

[0028] In an embodiment of the present application, the above amphiphilic compound is selected from any one or more of ester-based amphiphilic compounds and / or phosphoric acid-based amphiphilic compounds; preferably, the amphiphilic compound is selected from any one or more of hydroxyethyl methacrylate, 2-phenylethyl diethyl phosphate, 2,2-diethoxyethyl diethyl phosphate, tetramethyl ethylenediphosphonic acid and 1-hydroxybutyl diethyl phosphate; more preferably, the amphiphilic compound is a combination of hydroxyethyl methacrylate and tetramethyl ethylenediphosphonic acid, and the mass ratio of hydroxyethyl methacrylate to tetramethyl ethylenediphosphonic acid is 1 : (1-2).

[0029] The ester-based amphiphilic compound contains an ester group, which usually corresponds to the stretching vibration of C=O and the deformation vibration of C-O-C in infrared spectrum, and these vibrations have absorption bands in the mid-infrared region, especially infrared light with a wavelength in the range of 7-11 μm; the phosphoric acid-based amphiphilic compound contains a phosphoric acid group, and the stretching vibration of phosphoryl group and the double bond vibration of P=O also have significant absorption in infrared spectrum. Controlling the type of amphiphilic compound in the above range helps to make the amphiphilic compound have certain infrared absorption capacity, thereby further improving the infrared absorption performance of the modified hydrotalcite. The ester-based amphiphilic compound and the phosphoric acid-based amphiphilic compound can produce a synergistic effect through intermolecular interaction. The C=O stretching vibration peak (1730-1750 cm -1 ) of the ester-based compound and the P=O stretching vibration peak (1220-1260 cm -1 ) of the phosphoric acid-based compound can be red-shifted due to the formation of hydrogen bonding, and the peak shape is widened, and the infrared absorption performance can be further significantly improved.

[0030] In an embodiment of the present application, the contact angle of the above modified hydrotalcite with water is 100°-160°.

[0031] The contact angle of the modified hydrotalcite with water is in the above range, and the modified hydrotalcite has certain hydrophobicity, which helps to improve the compatibility and dispersibility of the modified hydrotalcite in the polymer, thereby further improving the infrared absorption performance and visible light transmittance of the finally formed film.

[0032] In another typical embodiment of the present application, a preparation method of the aforementioned modified hydrotalcite is provided, which comprises: mixing the hydrotalcite, the amphiphilic compound and water, and then performing a modification reaction to obtain the modified hydrotalcite.

[0033] The modification reaction of the hydrotalcite and the amphiphilic compound in water helps to improve the uniformity of the distribution of the amphiphilic compound on the surface of the hydrotalcite, and to promote the bonding of the hydrophilic groups of the amphiphilic compound with the hydroxyl groups on the surface of the hydrotalcite to form covalent bonds, so as to obtain the modified hydrotalcite. The hydrophobic end of the amphiphilic compound is away from the surface of the hydrotalcite, which helps to regulate the hydrophobicity of the surface of the hydrotalcite, thereby improving the compatibility and dispersibility between the hydrotalcite and the polymer, and further improving the infrared absorption performance and the visible light transmittance of the thin film formed by the hydrotalcite and the polymer. Compared with the unmodified hydrotalcite, more modified hydrotalcite can be added into the polymer, so as to further improve the infrared absorption performance and the visible light transmittance of the thin film formed by the hydrotalcite and the polymer, and further improve the heat preservation performance and the transparency of the thin film.

[0034] In an embodiment of the present application, the temperature of the aforementioned modification reaction is 40-160°C, preferably 70-90°C; and / or, the time of the modification reaction is 0.5-6h, preferably 2-4h.

[0035] Controlling the temperature and the time of the modification reaction within the above ranges helps to promote the bonding of the hydrophilic groups of the amphiphilic compound with the hydroxyl groups on the surface of the hydrotalcite to form covalent bonds, thereby improving the efficiency of the modification reaction.

[0036] In an embodiment of the present application, the aforementioned preparation method of the hydrotalcite comprises: performing a crystallization treatment on a divalent metal ion source, a trivalent metal ion source, an interlayer anion source, water and a growth directing agent to obtain the hydrotalcite; the ratio of the total mass of the divalent metal ion source and the trivalent metal ion source to the mass of the growth directing agent is (0.5-2):1; the temperature of the crystallization treatment is 60-200°C, preferably 90-160°C, and the time of the crystallization treatment is 0.5-36h, preferably 6-8h.

[0037] Controlling the ratio of the total mass of the divalent metal ion source and the trivalent metal ion source to the mass of the growth directing agent within the above ranges helps to guide the hydrotalcite to form a two-dimensional layered structure. Controlling the temperature and the time of the crystallization treatment within the above ranges helps to promote the formation of the hydrotalcite and reduce the generation of side reactions, thereby improving the efficiency of the crystallization treatment.

[0038] The divalent metal ion source is selected from any one or more of Mg(OH)2, Mg(NO3)2.6H2O, zinc hydroxide, zinc nitrate, calcium hydroxide, and calcium nitrate; the trivalent metal ion source is selected from any one or more of Al(OH)3, Al(NO3)3.9H2O, iron hydroxide, and iron nitrate; and the interlayer anion source is selected from any one or more of carbon dioxide, Na2CO3, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, (2-hydroxyethyl) phosphonic acid, succinyl phosphonic acid, and phenyl phosphonic acid.

[0039] In an embodiment of the present application, the growth-directing agent is selected from any one or more of an alcohol compound, an amine compound, and a quaternary ammonium salt compound; preferably, the growth-directing agent is selected from any one or more of ethanol, ethylene glycol, hexamethylenetetramine, and cetyltrimethylammonium bromide; further preferably, the growth-directing agent is a combination of ethylene glycol and hexamethylenetetramine, and the mass ratio of ethylene glycol to hexamethylenetetramine is 1:(0.2-0.8).

[0040] Controlling the type of growth-directing agent within the above range helps to prepare a two-dimensional layered structure of hydrotalcite with a suitable ab-axis direction and number of stacked layers, thereby further improving the infrared absorption performance of the hydrotalcite. The alcohol and amine compounds as the synergistic growth-directing agent can significantly adjust the growth behavior of the hydrotalcite, in which the alcohol delays the vertical accumulation of the crystal by the coordination of the hydroxyl group with the metal ion of the hydrotalcite layer, and promotes the lateral growth of the two-dimensional layer, while the amine compound realizes the regulation of the interlayer spacing and the crystal orientation by the electrostatic interaction of the amino group with the interlayer anion and the construction of the hydrogen bond network. The two play a synergistic role to realize the regulation of the two-dimensional size of the hydrotalcite.

[0041] In yet another typical embodiment of the present application, a master batch is provided, comprising a polymer and an additive, the additive comprising the aforementioned modified hydrotalcite or the modified hydrotalcite prepared by the aforementioned preparation method; preferably, the polymer is selected from polyethylene and / or polypropylene; preferably, the weight content of the modified hydrotalcite in the master batch is 5-80%.

[0042] Since the master batch contains the modified hydrotalcite of the present application, the master batch has excellent infrared light absorption performance.

[0043] In an embodiment of the present application, the master batch composition comprises 5-80 parts by mass of the modified hydrotalcite, 19-85 parts by mass of PE, and 1-10 parts by mass of polyethylene wax.

[0044] In an embodiment of the present application, the master batch composition comprises 5-80 parts by mass of the modified hydrotalcite and 20-95 parts by mass of PE.

[0045] In one embodiment of the present application, the preparation method of the master batch comprises: loading the polymer into an internal mixer, pre-melting and stirring at a temperature of 130-150°C, adding the modified hydrotalcite and polyethylene wax, and mixing for 3-60 minutes; heating the twin-screw extruder to 130-170°C, and feeding the uniformly mixed material into the twin-screw extruder for extrusion, pelletization and drying to obtain the master batch.

[0046] In another typical embodiment of the present application, a film is provided, which is prepared by sequentially mixing the master batch and the polymer in an internal mixer and calendering.

[0047] Since the master batch for preparing the film contains the modified hydrotalcite of the present application, the film has excellent infrared light absorption performance and visible light transmittance, and can have good heat preservation effect and good transparency.

[0048] In one embodiment of the present application, the preparation method of the film comprises: mixing the master batch and the polymer uniformly, feeding into an internal mixer, mixing and internal mixing at 130-150°C for 20-40 minutes, and then feeding the mixed material into a flat curing press for calendering at 130-150°C to obtain the film.

[0049] In one embodiment of the present application, the film has a thickness of 100-200 μm.

[0050] In another typical embodiment of the present application, the film is applied as an agricultural film.

[0051] The beneficial effects of the present application will be further illustrated by the following examples.

[0052] Example 1

[0053] A mixed slurry was prepared by weighing 13.92 g of Mg(OH)2, 9.36 g of Al(OH)3 and 267.72 g of deionized water; the slurry was transferred into a 500 mL high-pressure reactor, 26.78 g of hexamethylenetetramine was weighed and added into the mixed slurry for uniform stirring, the ratio of the total mass of Mg(OH)2 and Al(OH)3 to the mass of hexamethylenetetramine was 0.87:1, carbon dioxide was introduced at a temperature of 160°C, the reactor pressure was 0.8 MPa, and the hydrotalcite slurry was obtained by crystallization treatment under stirring for 6 hours, the contact angle of the hydrotalcite with water was 70°, then the slurry was stirred and cooled to 80°C, 1.458 g of hydroxyethyl methacrylate was weighed and added, and the modification reaction was carried out at 80°C for 2 hours, and then the slurry was cooled to room temperature, centrifuged and dried at 60°C for 12 hours to obtain the modified hydrotalcite, the mass ratio of the hydrotalcite to the hydroxyethyl methacrylate in the modified hydrotalcite was 1:0.04, and the chemical formula of the hydrotalcite was Mg 2+ 0.67 Al 3+0.33 (OH)2(CO3 2- ) 0.17 • 0.67H2O, the ab axis direction particle size of the hydrotalcite is 2.1 μm, the average stacking layer number is 36, and the contact angle of the modified hydrotalcite with water is 113°.

[0054] The above modified hydrotalcite 800 g, polyethylene 195 g, and polyethylene wax 5 g were weighed, the polyethylene was loaded into a banbury mixer, pre-melt mixed and stirred at 140°C for 10 min, then the polyethylene wax was added and mixed for 5 min, and then the modified hydrotalcite was added and banbury mixed for 30 min. The material uniformly mixed by banbury mixing was added into a twin-screw extruder, which was heated to 150°C and kept for 30 min, and then extruded and granulated at a rotation speed of 100 r / min, a melt temperature of 145°C, and a plasticizing time of 8 min, and dried in an oven at 60°C for 10 h to obtain a master batch with an average length of 3 mm.

[0055] The above master batch 12.5 g and polyethylene 187.5 g were weighed, uniformly mixed, and then added into a banbury mixer, mixed and banburyed at 140°C for 30 min to obtain a hydrotalcite / PE composite material with an addition amount of 5%; and then the hydrotalcite / PE composite material was placed into a flat curing machine, and a film with an average thickness of 150 μm was obtained by calendering at 140°C.

[0056] Example 2

[0057] A mixed slurry was prepared by weighing 31.87 g of Mg(OH)2, 21.43 g of Al(OH)3, and 612.95 g of deionized water; the slurry was transferred to a 1000 mL high-pressure reaction kettle, and then 41 g of ethylene glycol was added to the slurry, the mass ratio of the total mass of Mg(OH)2 and Al(OH)3 to the mass of ethylene glycol was 1.3:1, the temperature was raised to 150°C, carbon dioxide was introduced, the pressure of the reaction kettle was 1.0 MPa, and the crystallization treatment was carried out for 8 h to obtain a hydrotalcite slurry. After stirring and cooling to 80°C, 0.73 g of tetramethyl ethylene diphosphonic acid was added, and a modification reaction was carried out for 4 hours, and then the temperature was cooled to room temperature, centrifuged, and dried in an oven at 60°C for 12 hours to obtain a modified hydrotalcite, the mass ratio of the hydrotalcite to tetramethyl ethylene diphosphonic acid in the modified hydrotalcite was 1:0.042, and the chemical formula of the hydrotalcite was Mg 2+ 0.67 Al 3 + 0.33 (OH)2(CO3 2- ) 0.17 • 0.67H2O, the ab axis direction particle size of the hydrotalcite is 2.1 μm, the average stacking layer number is 36, and the contact angle of the modified hydrotalcite with water is 113°.

[0058] Take 800g of the modified hydrotalcite, 195g of polyethylene, and 5g of polyethylene wax. Put the polyethylene into a mixer, pre-melt and mix at 140°C for 10 minutes. Then add the polyethylene wax and mix for 5 minutes. Add the modified hydrotalcite and mix for 30 minutes. Heat the twin-screw extruder to 145°C and keep the temperature constant for 30 minutes. Put the mixed material into the twin-screw extruder, extrude and granulate at a speed of 100r / min, a melt temperature of 145°C, and a plasticizing time of 8 minutes. Dry in an oven at 60°C for 10 hours to obtain a master batch with an average length of 3mm.

[0059] Take 12.5g of the master batch and 187.5g of polyethylene. Mix them well and put them into a mixer. Mix at 140°C for 30 minutes to obtain a hydrotalcite / PE composite material with an addition amount of 5%. Put the hydrotalcite / PE composite material into a flat vulcanizing machine and press at 140°C to obtain a film with an average thickness of 150μm.

[0060] Example 3

[0061] The difference from Example 1 is that the mass of hydroxyethyl methacrylate is 0.729. The final film is obtained, wherein the mass ratio of hydrotalcite to hydroxyethyl methacrylate in the modified hydrotalcite is 1:0.020, and the contact angle of the modified hydrotalcite with water is 110°.

[0062] Example 4

[0063] The difference from Example 1 is that the mass of hydroxyethyl methacrylate is 5.468. The final film is obtained, wherein the mass ratio of hydrotalcite to hydroxyethyl methacrylate in the modified hydrotalcite is 1:0.150, and the contact angle of the modified hydrotalcite with water is 122°.

[0064] Example 5

[0065] The difference from Example 1 is that the mass of hydroxyethyl methacrylate is 6.561. The final film is obtained, wherein the mass ratio of hydrotalcite to hydroxyethyl methacrylate in the modified hydrotalcite is 1:0.180, and the contact angle of the modified hydrotalcite with water is 102°.

[0066] Example 6

[0067] The difference from Example 1 is that the combination of hydroxyethyl methacrylate and tetramethyl ethylene diphosphonic acid is used to replace hydroxyethyl methacrylate, and the mass ratio of hydroxyethyl methacrylate to tetramethyl ethylene diphosphonic acid in the combination is 1:1.0. The final film is obtained, and the contact angle of the modified hydrotalcite with water is 121°.

[0068] Example 7

[0069] The difference from Example 1 is that the combination of hydroxyethyl methacrylate and tetramethylene ethylene diphosphonic acid is used to replace hydroxyethyl methacrylate, and the mass ratio of hydroxyethyl methacrylate and tetramethylene ethylene diphosphonic acid in the combination of hydroxyethyl methacrylate and tetramethylene ethylene diphosphonic acid is 1:2.0, and finally a film is obtained, and the contact angle of the modified hydrotalcite with water is 127°.

[0070] Example 8

[0071] The difference from Example 1 is that the mass of hexamethyl tetramine is 15.52g, and the mass ratio of the total mass of Mg(OH)2 and Al(OH)3 to the mass of hexamethyl tetramine is 1.5:1, and finally a film is obtained. Among them, the average particle size of the ab axis direction of the hydrotalcite is 1.9μm, and the average stacking layer number is 43 layers.

[0072] Example 9

[0073] The difference from Example 1 is that the mass of hexamethyl tetramine is 46.56g, and the mass ratio of the total mass of Mg(OH)2 and Al(OH)3 to the mass of hexamethyl tetramine is 0.5:1, and finally a film is obtained. Among them, the average particle size of the ab axis direction of the hydrotalcite is 2.4μm, and the average stacking layer number is 26 layers.

[0074] Example 10

[0075] The difference from Example 1 is that the mass of hexamethyl tetramine is 7.76g, and the mass ratio of the total mass of Mg(OH)2 and Al(OH)3 to the mass of hexamethyl tetramine is 3:1, and finally a film is obtained. Among them, the average particle size of the ab axis direction of the hydrotalcite is 1.5μm, and the average stacking layer number is 70 layers.

[0076] Example 11

[0077] The difference from Example 1 is that the combination of ethylene glycol and hexamethyl tetramine is used to replace hexamethyl tetramine, and the mass ratio of ethylene glycol and hexamethyl tetramine in the combination of ethylene glycol and hexamethyl tetramine is 1:0.2, and finally a film is obtained. Among them, the average particle size of the ab axis direction of the hydrotalcite is 0.45μm, and the average stacking layer number is 7 layers.

[0078] Example 12

[0079] The difference from Example 1 is that the combination of ethylene glycol and hexamethyl tetramine is used to replace hexamethyl tetramine, and the mass ratio of ethylene glycol and hexamethyl tetramine in the combination of ethylene glycol and hexamethyl tetramine is 1:0.8, and finally a film is obtained. Among them, the average particle size of the ab axis direction of the hydrotalcite is 0.8μm, and the average stacking layer number is 12 layers.

[0080] Example 13

[0081] The difference from Example 1 is that 32.61 g of ZnO and 15.70 g of solid salt Al(OH)3 and 235.36 g of deionized water are weighed to prepare a mixed slurry; the slurry is transferred to a 500 mL high-pressure reaction kettle, and then 42.78 g of ethylene glycol is weighed into the slurry, the mass ratio of the total mass of ZnO and Al(OH)3 to the mass of ethylene glycol is 1.1:1, heated to 140°C, and carbon dioxide is introduced, the pressure of the reaction kettle is 0.7 MPa, and the slurry is crystallized for 8 h under stirring to obtain a hydrotalcite slurry, and the chemical formula of the hydrotalcite is Zn 2 + 0.67 Al 3+ 0.33 (OH)2(CO3 2- ) 0.17 ·0.67H2O. Stir and cool to 80°C, weigh 1.458 g of tetramethyl ethylene diphosphonic acid into it, and carry out modification reaction for 4 hours, then cool to room temperature, centrifuge, and dry in an oven at 60°C for 12 hours to obtain modified hydrotalcite, the mass ratio of hydrotalcite to tetramethyl ethylene diphosphonic acid in the modified hydrotalcite is 1:0.040, the average particle size in the ab axis direction of the hydrotalcite is 0.82 μm, and the average stacking layer number is 35 layers, and finally a film is obtained.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that the addition of hydroxyethyl methacrylate is cancelled, and finally a film is obtained.

[0084] Comparative Example 2

[0085] The difference from Example 1 is that the surface of the hydrotalcite is not modified with hydroxyethyl methacrylate, and 800 g of hydrotalcite, 195 g of polyethylene, and 5 g of polyethylene wax are weighed; the polyethylene is loaded into a banbury mixer, pre-melted and mixed at 140°C, and stirred for 10 min; then the polyethylene wax is added and mixed for 5 min, and then the hydrotalcite and 1.458 g of hydroxyethyl methacrylate are added, and the banbury mixing is carried out for 30 min. The banbury mixed material is added into a twin-screw extruder which is heated to 145°C and kept for 30 min, extruded and granulated in the twin-screw extruder at a rotation speed of 100 r / min, a melt temperature of 145°C, and a plasticizing time of 8 min, and dried in an oven at 60°C for 10 h to obtain a master batch with an average length of 3 mm.

[0086] The above master batch 12.5 g and polyethylene 187.5 g are weighed, mixed uniformly, and then added into a banbury mixer, mixed and banburyed at 140°C for 30 min to obtain a hydrotalcite / PE composite material with a hydrotalcite addition amount of 5%; then the hydrotalcite / PE composite material is placed into a flat curing press, and a film with an average thickness of 150 μm is obtained by calendering at 140°C.

[0087] Performance test

[0088] The films prepared from the examples and comparative examples were tested for visible light transmittance and infrared light absorption rate in the wavelength range of 1428-909cm -1 The results are shown in Table 1.

[0089] Table 1

[0090]

[0091]

[0092] Figure 1 The XRD pattern of the hydrotalcite in Example 1 of the present application is shown in Figure 1, and the results are shown in Table 1. Figure 1 It can be seen that the hydrotalcite has the typical structure of MgAl-CO3 LDHs.

[0093] Figure 2 The SEM pattern of the hydrotalcite in Example 1 of the present application is shown in Figure 2, and the results are shown in Table 1. Figure 2 It can be measured from Figure 2 that the particle size of the hydrotalcite in the ab axis direction is 2.1pm, and the average layer number is 36 layers.

[0094] From the above description, it can be seen that the above-mentioned examples of the present application achieve the following technical effects:

[0095] In the present application, the amphiphilic compound has a hydrophilic end and a hydrophobic end, the hydrophilic end forms a covalent bond with the hydroxyl group on the surface of the hydrotalcite by bonding, which helps the amphiphilic compound to stably exist on the surface of the hydrotalcite, and the hydrophobic end of the amphiphilic compound is away from the surface of the hydrotalcite, which helps to regulate the hydrophobicity of the surface of the hydrotalcite, thereby helping to improve the compatibility and dispersibility between the hydrotalcite and the polymer, thereby helping to improve the infrared absorption performance and visible light transmittance of the film formed by the hydrotalcite and the polymer, and compared with the unmodified hydrotalcite, more modified hydrotalcite can be added in the polymer, thereby helping to further improve the infrared absorption performance and visible light transmittance of the film formed by the hydrotalcite and the polymer, and further helping to improve the heat preservation performance and transparency of the film.

[0096] The above is only an example of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A modified hydrotalcite characterized in that, The modified hydrotalcite comprises hydrotalcite and an amphiphilic compound on the surface of the hydrotalcite, a hydrophilic end of the amphiphilic compound is combined with the surface of the hydrotalcite, and a hydrophobic end is away from the surface of the hydrotalcite.

2. The modified hydrotalcite according to claim 1, characterized in that, The mass ratio of the hydrotalcite to the amphiphilic compound is 1:(0.02-0.15); and / or, the hydrotalcite has a two-dimensional layered structure, the ab plane particle size of the hydrotalcite is 0.1-10 μm, preferably 0.2-3.5 μm, and the stacking layer number of the hydrotalcite is 2-60 layers, preferably 5-40 layers.

3. The modified hydrotalcite according to claim 1 or 2, characterized in that The chemical general formula of the hydrotalcite is M 2+ 1- x M 3+ x (OH)2(A n- ) x / n ·mH2O; wherein M 2+ is a divalent metal cation, M 3+ is a trivalent metal cation, A n- is an interlayer anion, x is M 3+ / (M 2+ + M 3+ ), 0.2≤x≤0.4, 0≤m≤6; Preferably, said M 2+ is any one or more of Mg 2+ , Zn 2+ and Ca 2+ . and / or, the M 3+ selected from Al 3+ and / or Fe 3+ ; and / or, the A n- selected from CO3 2- , SO4 2- , Cl - , NO 3- , PO4 3- , HPO4 2- , H2PO4 - , (2-hydroxyethyl)phosphonate, succinylphosphonate and phenylphosphonate.

4. The modified hydrotalcite according to any one of claims 1 to 3, characterized in that, The amphiphilic compound is selected from ester-based amphiphilic compounds and / or phosphoric acid-based amphiphilic compounds; Preferably, the amphiphilic compound is selected from any one or more of hydroxyethyl methacrylate, 2-phenylethyl diethyl phosphate, 2,2-diethoxyethyl diethyl phosphate, tetramethyl ethylene diphosphonic acid and 1-hydroxybutyl diethyl phosphate; More preferably, the amphiphilic compound is a combination of hydroxyethyl methacrylate and tetramethyl ethylene diphosphonic acid, and the mass ratio of the hydroxyethyl methacrylate to the tetramethyl ethylene diphosphonic acid is 1:(1-2).

5. A method for producing the modified hydrotalcite according to any one of claims 1 to 4, characterized by, The preparation method comprises: mixing hydrotalcite, an amphiphilic compound and water, and then performing a modification reaction to obtain the modified hydrotalcite.

6. The method of producing a modified hydrotalcite according to claim 5, characterized by, The modification reaction is performed at a temperature of 40-160 ℃ for a time of 0.5-6 h.

7. The method for producing a modified hydrotalcite according to claim 5 or 6, characterized by, The preparation method of the hydrotalcite comprises: performing a crystallization treatment on a divalent metal ion source, a trivalent metal ion source, an interlayer anion source, water and a growth-directing agent to obtain the hydrotalcite; The mass ratio of the total mass of the divalent metal ion source and the trivalent metal ion source to the mass of the growth-directing agent is (0.5-2.0):1; The crystallization treatment is performed at a temperature of 60-200 ℃ for a time of 0.5-36 h.

8. The method for producing a modified hydrotalcite according to claim 7, characterized by, The growth-directing agent is selected from any one or more of alcohol compounds, amine compounds and quaternary ammonium salt compounds; Preferably, the growth-directing agent is selected from any one or more of ethanol, ethylene glycol, hexamethylenetetramine and cetyltrimethylammonium bromide; Further preferably, the growth-directing agent is a combination of ethylene glycol and hexamethylenetetramine, and the mass ratio of the ethylene glycol to the hexamethylenetetramine is 1:(0.2-0.8).

9. A master batch comprising a polymer and an additive, characterized in that, The additive comprises the modified hydrotalcite of any one of claims 1-4 or the modified hydrotalcite prepared by the preparation method of any one of claims 5-8; preferably, the polymer is selected from polyethylene and / or polypropylene; preferably, the weight content of the modified hydrotalcite in the master batch is 5-80%.

10. A film, characterized by, The film is prepared by sequentially subjecting the master batch and the polymer of claim 9 to mixing and calendering.

11. Use of the film of claim 10 as an agricultural film.

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