Infrared heat-retaining film containing phosphonic group-containing hydrotalcite

Abstract

The application provides an infrared heat preservation film containing phosphine group hydrotalcite, which comprises linear low density polyethylene (LLDPE) and ethylenediamine tetramethylene phosphonic ion intercalated hydrotalcite, and the molecular formula of the intercalated hydrotalcite is: (M 2+ ) 1‑x (M 3+ ) x (OH)2(C6H 19 N2O 12 P4 ‑ ) a (NO3 ‑ ) b ) mH2O; wherein M 2+ is Zn 2+ or Mg 2+ ; M 3+ is Al 3+ or Fe 3+ ; 0.1 < X < 0.8; a and b are the amounts of C6H 19 N2O 12 P4 ‑ and NO3 ‑ respectively, n×a+b=X; m is the amount of crystal water, 0.01

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal insulation film, and particularly relates to an infrared thermal insulation film material containing phosphine group hydrotalcite. BACKGROUND

[0002] The agricultural film made of polyethylene has the characteristics of light and soft texture, good light transmission, non-toxicity, and easy molding processing, and is widely used in various greenhouse films and mulching films, and has made great contribution to the development of China's agriculture. However, the pure polyethylene film has poor thermal insulation performance and is not easy to bond, especially in cold regions, which is not conducive to the growth of plants and is difficult to meet the development requirements of agriculture. Researchers have found that mixing and doping with functional additives can simply and effectively prepare functional films and improve the thermal insulation performance. At present, the thermal insulation agents used to improve the thermal insulation performance of agricultural films are mainly inorganic minerals such as talc, kaolin, sericite and diatomite. However, these thermal insulation agents have a certain deviation from the heat loss in the 9-11 μm wave band of the night geothermal radiation in the infrared absorption wave band, and due to the presence of impurities, the dispersion in the film is uneven, and film bubbles are easily generated. Therefore, it has become an urgent need to find new thermal insulation agents for agricultural films and to prepare new thermal insulation agricultural films.

[0003] With the deepening of research, researchers have found that hydrotalcite has many advantages and can be widely used in different application fields. Research has found that hydrotalcite has infrared absorption in the 7-25 μm wave band. According to the infrared spectrum research on the influence of hydrotalcite on the performance of agricultural films published by Wang Liangyu, Cui Hailong and Jiao Hongwen, the influence of imported hydrotalcite, domestic hydrotalcite and talc powder on the optical performance, light transmittance, infrared barrier and thermal insulation performance of agricultural films was studied by using an infrared spectrometer. The results show that the particle size of domestic hydrotalcite is larger than that of imported hydrotalcite, and the haze value of the product increases by about 1.5%. Compared with the commonly used talc powder, the infrared barrier effect of the agricultural film prepared by the hydrotalcite is better, which shows that the application of hydrotalcite in thermal insulation materials has obvious advantages. In addition, hydrotalcite also has the advantage of intercalation assembly, and has high application value as a plastic additive body or carrier. Therefore, it can use the exchangeability of the interlayer anion to introduce an organic absorbent with infrared absorption into the interlayer, broaden the infrared absorption range of the hydrotalcite, and improve its infrared absorption capacity. Therefore, hydrotalcite has great advantages as a new type of agricultural film thermal insulation agent. According to the literature, Wang Lijing, Xu Xiangzi, Evans DG, etc. titled Performance Research of Dihydrogen Phosphate Intercalated Hydrotalcite under Acidic Conditions, showed that by ion exchange, dihydrogen phosphate anions and CO3 2- were assembled into the interlayer of hydrotalcite to prepare MgAl-H2PO4-LDHs with a supramolecular intercalation structure, and the film made of PE showed significant selective infrared absorption performance.

[0004] According to the existing material development status, a large number of scientific researchers have been looking for a kind of agricultural film with balanced improvement of thermal insulation, thermal stability and mechanical properties. SUMMARY

[0005] The present application aims to provide a thermal insulation film with strong and wide absorption effect on geothermal infrared radiation, improved thermal insulation performance, good thermal stability and mechanical properties, which can be applied to agricultural films to effectively improve the film insulation effect of crops at night.

[0006] To achieve the above-mentioned purpose, the present application provides an infrared thermal insulation film containing phosphine group hydrotalcite, which comprises linear low density polyethylene LLDPE and ethylenediamine tetramethylene phosphonate ion intercalated hydrotalcite, abbreviated as EDTMPS-LDH, and its molecular formula is: (M 2+ ) 1-x (M 3+ ) x (OH)2(C6H 19 N2O 12 P4 - ) a (NO3 - ) b ·mH2O. Wherein M 2+ is Zn 2+ or Mg 2+ ; M 3+ is Al 3+ or Fe 3+ ; 0.1<X<0.8; a, b are the amounts of C6H 19 N2O 12 P4 - and NO3 - , a+b=X; m is the amount of crystal water, 0.01<m<4.

[0007] Preferably, the EDTMPS-LDH is surface modified by silane coupling agent KH570 to form KH570-EDTMPS-LDH.

[0008] Further, the content of KH570-EDTMPS-LDH is 1% to 4% of the mass of linear low density polyethylene LLDPE.

[0009] Further, the content of KH570-EDTMPS-LDH is 2% of the mass of linear low density polyethylene LLDPE.

[0010] Preferably, the infrared thermal insulation film containing phosphine group hydrotalcite is prepared by the following method:

[0011] S1. Take the preset mass proportion of KH570-EDTMPS-LDH and LLDPE, mix uniformly to form a mixture;

[0012] S2. Set the film blowing parameters, after the temperature is stabilized to 190 DEG C, put the above mixture,

[0013] S3. Start the "traction valve", "winding", "screw" in turn, after heating and blending extrusion, start the film blowing, and the infrared heat preservation film can be obtained.

[0014] The beneficial effects of the present application are: compared with the existing heat preservation film, the LLDPE film prepared by adding KH570-EDTMPS-LDH heat preservation material has the following advantages:

[0015] (1) The heat preservation performance of KH570-EDTMPS-LDH LLDPE film, the light absorption area of 9-11 mu band of the LLDPE film added with KH570-EDTMPS-LDH is larger than that of pure LLDPE film, the light absorption area of the LLDPE film added with 4% mass fraction of KH570-EDTMPS-LDH is increased by 105%, the temperature in the heat preservation film shed decreases by 4%-15% during the day, and the temperature increases by 4%-17% at night.

[0016] (2) The thermal stability of the LLDPE film added with KH570-EDTMPS-LDH is improved, the thermal stability of the film is improved, the carbon residue amount of the LLDPE film added with 2% and 4% of KH570-EDTMPS-LDH is increased by 39.2% and 36.6% respectively compared with the pure LLDPE film, and the carbonization of LLDPE is promoted.

[0017] (3) In terms of mechanical properties, KH570 enhances the interfacial compatibility of EDTMPS-LDH and LLDPE, and KH570-EDTMPS-LDH effectively improves the mechanical properties of LLDPE. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The FT-IR spectra of the comparative sample and samples 2 and 3 are shown in the following table:

[0019] Figure 2 The FT-IR spectra of the comparative sample and samples 2 and 3 are shown in the following table: Figure 1 The local enlarged view of the spectrum in 9-11 mu;

[0020] Figure 3 The (a) TG curve and (b) DTG curve of the comparative sample and samples 2 and 3 under nitrogen atmosphere are shown in the following table: DETAILED DESCRIPTION

[0021] The embodiments described below are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] The infrared thermal insulation film containing phosphine-containing hydrotalcite provided by the present application comprises linear low-density polyethylene (LLDPE) and ethylenediamine tetramethylene phosphonic acid ion intercalated hydrotalcite, which is abbreviated as EDTMPS-LDH, and has a molecular formula of: (M 2+ ) 1-x (M 3+ ) x (OH)2(C6H 19 N2O 12 P4 - ) a (NO3 - ) b ·mH2O. Wherein M 2+ is Zn 2+ or Mg 2+ ; M 3+ is Al 3+ or Fe 3+ ; 0.1 < X < 0.8; a and b are the amounts of C6H 19 N2O 12 P4 - and NO3 - , respectively, and a + b = X; m is the amount of crystal water, and 0.01 < m < 4.

[0023] Preferably, the EDTMPS-LDH is surface-modified by silane coupling agent KH570 to form KH570-EDTMPS-LDH. Moreover, the amount of the KH570-EDTMPS-LDH is 1% to 4% of the mass of the linear low-density polyethylene (LLDPE), preferably 2%.

[0024] More specifically, the ethylenediamine tetramethylene phosphonic acid ion intercalated hydrotalcite is prepared by the following steps:

[0025] Step 1, preparing a nitrate type hydrotalcite precursor, mixing a certain proportion of a divalent metal salt solution and a trivalent metal salt solution to obtain a mixed salt solution, then stirring and mixing the mixed salt solution and an alkali solution uniformly, filtering and washing until the filtrate has a neutral pH after crystallization, drying, and grinding to obtain the hydrotalcite precursor;

[0026] Step two, the hydrotalcite precursor is uniformly dispersed in deionized water to obtain a hydrotalcite aqueous solution, and EDTMP sodium is dissolved in deionized water to prepare an EDTMP sodium solution; under the protection of nitrogen, the EDTMP sodium solution is slowly added to the hydrotalcite aqueous solution while being rapidly stirred, and after reflux crystallization, filtration, washing, drying and grinding, the EDTMP ion intercalated hydrotalcite selective infrared absorption material is obtained.

[0027] The addition ratio of the divalent metal salt solution and the trivalent metal salt solution is 0.003-0.1:0.01. The crystallization time in step one is 48h, and the crystallization temperature in step two is 80℃, and the crystallization time is 10h.

[0028] EDTMPS-LDH is dissolved in deionized water and transferred to a reaction container, and a predetermined mass ratio of KH570 is dissolved in alcohol water, and then added to the above reaction container, heated and stirred for 2h, filtered and washed to remove excess impurities, dried and ground, and the sample is sieved to 600 meshes to obtain KH570-EDTMPS-LDH.

[0029] The infrared insulation film containing the phosphine-containing hydrotalcite can be prepared by the following method:

[0030] S1. A predetermined mass ratio of KH570-EDTMPS-LDH and LLDPE is weighed and uniformly mixed to form a mixture;

[0031] S2. Set the film blowing parameters, and after the temperature is stabilized to 190℃, the above mixture is put in,

[0032] S3. Start the "pull valve", "winding" and "screw" in sequence, and the infrared insulation film can be obtained by heating and blending extrusion and starting the film blowing.

[0033] The application will be described in detail below through specific examples, and the beneficial effects of the application will be verified through specific comparative experiments.

[0034] The application provides a preparation method of KH570-EDTMPS-LDH, and the phosphine-containing hydrotalcite obtained therefrom is used for film preparation and performance detection with LLDPE.

[0035] The specific preparation steps are as follows:

[0036] (1) 0.02 mol Zn(NO3)2.6H2O and 0.01 mol Al(NO3)3.9H2O were dissolved in deionized water to prepare 100 ml of mixed A liquid; 0.1 mol NaOH was dissolved in deionized water to prepare B liquid, then B liquid was slowly added to A liquid to make its pH neutral, crystallized for 48 h, then filtered and washed until the pH of the filtrate was about 7, and dried to obtain hydrotalcite precursor. The dried hydrotalcite precursor was ultrasonically dispersed in deionized water to prepare 100 ml of suspension, which was transferred to a three-necked flask and stirred uniformly.

[0037] (2) 0.1 mol of ethylenediamine tetramethylene phosphonic acid sodium (EDTMPSNa) was weighed and dissolved in 100 ml of deionized water, and placed in a constant pressure funnel for use.

[0038] (3) Under the protection of nitrogen, the EDTMPS sodium solution in step (2) was slowly added to the hydrotalcite precursor suspension in step (1), and crystallized at 80°C for 10 h, then filtered and washed until the filtrate was neutral, and dried to obtain ZnAl-EDTMPS-LDH. The chemical formula of ZnAl-EDTMPS-LDH was calculated by ICP-AES analysis to be Zn 0.642 Al 0.358 (OH)2(C6H 19 N2O 12 P4 - ) 0.358 ·0.48H2O.

[0039] (4) The above ZnAl-EDTMPS-LDH was dissolved in deionized water and transferred to a reaction vessel, and 0.1 mol of KH570 was weighed and dissolved in alcohol water, then added to the above reaction vessel, heated and stirred for 2 h, filtered and washed to remove excess impurities, dried and ground, and the sample was sieved to 600 meshes to obtain KH570-ZnAl-EDTMPS-LDH.

[0040] Example 1

[0041] This example used the above ethylenediamine tetramethylene phosphonic acid ion intercalated hydrotalcite KH570-ZnAl-EDTMPS-LDH as raw material to prepare a film with LLDPE, and the preparation steps were as follows:

[0042] S1. KH570-ZnAl-EDTMPS-LDH and LLDPE were weighed in a mass ratio of 1:100, mixed uniformly to form a mixture;

[0043] S2. The film blowing parameters were set, and after the temperature was stabilized to 190°C, the above mixture was put in,

[0044] S3. Start the "pull valve", "winding", "screw" in turn, through the heating blending extrusion, start blowing film can get infrared insulation film sample 1.

[0045] The same components are prepared into 1 mm thick experimental sample 1 by a flat plate vulcanizer.

[0046] Example 2

[0047] S1. Take KH570-ZnAl-EDTMPS-LDH and LLDPE with a mass ratio of 2:100, mix uniformly to form a mixture;

[0048] S2. Set the film blowing parameters, after the temperature is stable to 190℃, put in the above mixture,

[0049] S3. Start the "pull valve", "winding", "screw" in turn, through the heating blending extrusion, start blowing film can get infrared insulation film sample 2.

[0050] The same components are prepared into 1 mm thick experimental sample 2 by a flat plate vulcanizer.

[0051] Example 3

[0052] S1. Take KH570-ZnAl-EDTMPS-LDH and LLDPE with a mass ratio of 4:100, mix uniformly to form a mixture;

[0053] S2. Set the film blowing parameters, after the temperature is stable to 190℃, put in the above mixture,

[0054] S3. Start the "pull valve", "winding", "screw" in turn, through the heating blending extrusion, start blowing film can get infrared insulation film sample 3.

[0055] The same components are prepared into 1 mm thick experimental sample 3 by a flat plate vulcanizer.

[0056] Comparative Example 1

[0057] S1. Take 100 parts of LLDPE to form a film blowing material;

[0058] S2. Set the film blowing parameters, after the temperature is stable to 190℃, put in the above film blowing material,

[0059] S3. Start the "pull valve", "winding", "screw" in turn, through the heating blending extrusion, start blowing film can get film comparative sample.

[0060] The same components are prepared into 1 mm thick comparative sample by a flat plate vulcanizer.

[0061] The thin film samples described in Examples 1-3 and Comparative Example 1 were subjected to infrared quantitative testing, and the test results are shown in Table 1:

[0062] Table 1. Absorbance area of samples at 9-11 μm

[0063] Absorbance Area Comparative Sample 21 Sample 1 25 Sample 2 28 Sample 3 43

[0064] According to the above experimental data and in combination with Figure 1 As can be seen from the FT-IR spectra of the comparative sample, samples 2 and 3, the heat stored on the ground during the day is mainly radiated in the infrared wave range of 7-25 μm (1428-400 cm -1 ) at night, and the heat dissipation in the range of 9-11 μm (1111-909 cm -1 ) is as high as 90%. According to the FT-IR spectra of the comparative sample, samples 2 and 3, the heat retention performance of the thin film can be reflected by calculating the absorbance area in the infrared range of 9-11 μm (1111-909 cm -1 ). Referring to Figure 2 The FT-IR spectra in the range of 9-11 μm were locally magnified to calculate the absorbance area. As can be seen, after the addition of KH570-ZnAl-EDTMPS-LDH, the absorbance of the LLDPE thin film is improved, and the absorbance in the range of 9-11 μm increases with the increase of the amount of KH570-ZnAl-EDTMPS-LDH, and thus the absorption area also increases. The absorbance area of the pure LLDPE thin film is 21. Through comparative analysis and calculation, when the amount of KH570-ZnAl-EDTMPS-LDH is 2% and 4%, the infrared absorbance area of the LLDPE thin film is increased by 33% and 105%, respectively, and when the amount of KH570-ZnAl-EDTMPS-LDH is 4%, the absorbance area of the LLDPE thin film is significantly improved, which shows that KH570-ZnAl-EDTMPS-LDH is beneficial to improve the heat retention performance of the LLDPE thin film and can be applied to the preparation of LLDPE thin film as an excellent heat retention material.

[0065] The thermal stability of the comparative sample and samples 2 and 3 was analyzed, and the (a) TG curve and (b) DTG curve of the above samples under nitrogen atmosphere are shown in Figure 3 The TG data of the comparative sample and samples 2 and 3 under nitrogen atmosphere are shown in Table 2.

[0066] Table 2. TG data of samples

[0067]

[0068] From Table 2 and Figure 3It can be seen that the thermal decomposition of LLDPE film and KH570-EDTMPS-LDH composite film is one step. The maximum decomposition temperature T max The difference is not big, but with the increase of the amount of hydrotalcite, the T max is much higher than that of pure LLDPE film. Moreover, the carbon residue of KH570-EDTMPS-LDH / LLDPE composite film with an addition amount of 2% and 4% is 5.36% and 5.26% respectively, which is higher than that of pure LLDPE film of 3.85%, and increases by 39.2% and 36.6% respectively, which can obviously improve the thermal stability of pure LLDPE film.

[0069] Tensile strength and elongation at break are two important parameters for evaluating the mechanical properties of composite materials. The mechanical properties of LLDPE composite material added with modified KH570-EDTMPS-LDH are tested, and the tensile strength and elongation at break obtained by testing are as follows in Table 3:

[0070] Table 3. Mechanical property test data of samples

[0071] Tensile Strength (MPa) Elongation at Break (%) Comparative Specimen 12.40 719.08 Specimen 1 12.97 776.81 Specimen 2 13.35 792.68 Specimen 3 14.44 817.46

[0072] From Table 3, it can be seen that the tensile strength and elongation at break of pure LLDPE are 12.40 MPa and 719.08% respectively, and with the increase of the amount of KH570-EDTMPS-LDH, the tensile strength and elongation at break of LLDPE matrix are increased by 7.7% and 16.5% respectively, which indicates that the addition of KH570-EDTMPS-LDH can obviously improve the mechanical properties of LLDPE.

[0073] In addition, the application also uses self-made simulation heat preservation device to carry out heat preservation test on LLDPE film added with KH570-EDTMPS-LDH, and the test data are shown in Table 4. The new heat preservation material does not block the entry of sunlight, has good light transmittance, does not affect the conversion of heat, and the change of KH570-EDTMPS-LDH content has little effect on the temperature change in the film. Compared with LLDPE film without adding LDHs, the inner temperature of LLDPE film added with KH570-EDTMPS-LDH decreases by 4% to 15%, so the film can better protect crops in the film from high temperature exposure in the daytime. In the night, the film inner temperature increases by about 4% to 17%, and the heat preservation property is better. This is because at night, the air temperature is low, and the soil emits heat in the form of long-wave infrared (5-10 μm). The film absorbs the infrared wave band of the heat radiation of the soil, reduces the heat loss as much as possible, reduces the infrared heat loss, slows down the temperature reduction, so that the agricultural film has good heat preservation property, which is beneficial to agricultural production.

[0074] Table 4. Heat preservation test data of samples

[0075]

[0076] The above describes the application in detail in combination with the embodiments. In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined and changed in any appropriate manner without contradiction, and the application will not describe various possible combination manners again. In addition, other modifications and combinations of various technical features according to the application should also be considered as disclosed content of the application, and all belong to the protection scope of the application.

Claims

1. An infrared-reflective, heat-protective film comprising a phosphine group-containing hydrotalcite, characterized by, The thermal insulation film contains linear low density polyethylene (LLDPE) and ethylenediamine tetramethylene phosphonic acid ion intercalated hydrotalcite, the abbreviated form of the intercalated hydrotalcite is EDTMPS-LDH, and its molecular formula is: (M 2+ ) 1-x (M 3+ ) x (OH)2(C6H 19 N2O 12 P4 - ) a (NO3 - ) b •mH2O; where M 2+ is Zn 2+ or Mg 2+ ; M 3+ is Al 3+ or Fe 3+ ; 0.1 < X < 0.8; a and b are the amounts of C6H 19 N2O 12 P4 - and NO3 - respectively, and a + b = X; m is the amount of crystal water, 0.01 < m < 4; the EDTMPS-LDH is surface modified by a silane coupling agent KH570 to form KH570-EDTMPS-LDH, and the content of the KH570-EDTMPS-LDH is 1% to 4% of the mass of the linear low density polyethylene LLDPE.

2. The infrared-reflecting, phosphonic group-containing hydrotalcite film according to claim 1, wherein: The KH570-EDTMPS-LDH content is 2% of the mass of the linear low-density polyethylene LLDPE.

3. The infrared-reflecting, phosphonic group-containing hydrotalcite film according to claim 1, wherein: It is prepared by the following method: S1. A predetermined mass ratio of KH570-EDTMPS-LDH and LLDPE is weighed and uniformly mixed to form a mixture; S2. The film blowing parameters are set, and after the temperature is stabilized to 190°C, the above mixture is put in, S3. Start the "pull valve", "winding", and "screw" in sequence, pass through the heating and blending extrusion, and start the film blowing to obtain the infrared heat preservation film.

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