Nucleating agent as well as preparation method and application thereof

Abstract

The invention provides a nucleating agent as well as a preparation method and application thereof. The structure of the nucleating agent is shown as a formula I, the nucleating agent belongs to an organophosphate compound nucleating agent in an alpha nucleating agent, contains a benzene ring and a carbon-carbon triple bond, has relatively good thermal stability, and ensures that the nucleating agent is not molten, not decomposed and in a microparticle shape at a polymer melting point of EVOH in a subsequent application process of preparing the EVOH; meanwhile, the para-position and the carbon-carbon triple bond of the benzene ring are connected with polar groups, so that the whole nucleating agent shows polarity and can be uniformly dispersed in polar EVOH. Furthermore, a polar group in a carbon-carbon triple bond, namely, R1 contains a flexible rotatable functional group, so that the flexibility of the EVOH crystal substance can be improved. The EVOH with excellent comprehensive performance can be obtained by adding a small amount of EVOH into the EVOH.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis and polymer synthesis, and specifically relates to a nucleating agent and a preparation method and application thereof. Background Art

[0002] Ethylene-vinyl alcohol polymer (EVOH) is a chain-like semi-crystalline material with the flexibility of polyethylene and the barrier properties of polyvinyl alcohol, and is mostly used in the field of flexible packaging. At present, the transparency, oxygen barrier properties, mechanical properties and thermal stability of domestic EVOH are poor, which makes it impossible to achieve industrial production and limits its application range. Therefore, producing high-quality EVOH and expanding the EVOH market have become issues that need to be urgently addressed.

[0003] Crystallinity is one of the key factors affecting the quality of EVOH. Studies have shown that the higher the crystallinity, the more tightly the EVOH molecular chains are stacked and the less likely they are to move freely, thus improving the gas barrier and thermodynamic properties. However, high crystallinity also reduces the flexibility of the material, limiting the application of the prepared EVOH. In order to obtain EVOH with excellent comprehensive performance, domestic and foreign researchers have made many efforts.

[0004] Y. Prykhodko's team prepared a partial hydrolysis product of ethylene-vinyl acetate polymer (EVA), namely EVA-OH polymer, which has better flexibility than EVOH, but has a low degree of alcoholysis and a low hydroxyl content, so the crystallinity is greatly reduced, thereby reducing the thermal stability of the material.

[0005] [P] Studies have reported that increasing the ethylene content is a common method to improve the flexibility of EVOH. Caroline Maes et al. compared the barrier properties of EVOH with different ethylene contents and found that the higher the ethylene content, the worse the barrier properties of the material. Wang Zijun et al. used polyvinyl alcohol acid as an additive and melt blended polyglycolic acid with EVOH to improve the crystallinity of EVOH. However, a small amount of this additive will destroy the EVOH crystal structure and reduce the crystallinity. Experiments have found that only when the amount of polyvinyl alcohol acid added is >20 wt% can it improve the crystallinity and flexibility of EVOH. [ / P][ Summary of the invention

[0006] In view of this, the object of the present invention is to provide a nucleating agent and a preparation method and application thereof. The nucleating agent can be applied to the preparation of EVOH to obtain EVOH with excellent comprehensive performance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a nucleating agent as shown in Formula I:

[0009] Formula I;

[0010] Wherein, R1 is selected from -(CH2) n -OH, -OCO(CH2) m CH3, -(CH2) x -Br, -(CH2) y -F, -CH2OOCH3, -CH2CH2OOCH3, -C((CH3)2(NH2));

[0011] n, m, x, and y are independently selected from any integer between 0 and 3;

[0012] R2 and R3 are each independently selected from OH-, -COOH, CH3COO-, -CH2COOH, -CH2NH2, -COCH3, -CH2OH, CH3CONH-, -NH2, -N-(CH3)2 or CH3-O-.

[0013] Preferably, n is 1 or 2, m is 0, 1 or 2; x is 2 or 3; and y is 1 or 2.

[0014] Preferably, the nucleating agent is selected from any one of the following formulas 1 to 3:

[0015] Formula 1; Formula 2; Formula 3.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned nucleating agent, comprising the following steps:

[0017] The compound represented by formula A reacts with the compound represented by formula B in the presence of a solvent to obtain a nucleating agent represented by formula I;

[0018] Formula A; Formula B;

[0019] Preferably, the solvent is selected from benzene solvents.

[0020] Preferably, the benzene solvent includes any one or more of benzene, toluene, xylene, trimethylbenzene or ethylbenzene.

[0021] Preferably, the reaction temperature is 105-130° C. and the reaction time is 0.5-5 h.

[0022] In a third aspect, the present invention provides a use of a nucleating agent prepared by the above preparation method in the preparation of EVOH.

[0023] In a fourth aspect, the present invention provides a method for preparing EVOH, comprising the following steps:

[0024] The nucleating agent is mixed with EVOH, dried, extruded and granulated to obtain the finished product.

[0025] Preferably, the mass ratio of the nucleating agent to EVOH is 1:50 to 1:100.

[0026] Preferably, the ethylene content in the EVOH is 10-90 wt%.

[0027] Preferably, the mixing time is 5 to 100 min.

[0028] Preferably, the drying temperature is 60-110° C., and the drying time is 1-24 h.

[0029] Preferably, the extrusion temperature is 150-250°C.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides a nucleating agent as shown in Formula I, which belongs to the organic phosphate compound nucleating agent among α nucleating agents, contains a benzene ring and a carbon-carbon triple bond, has good thermal stability, and ensures that in the subsequent application process of preparing EVOH, it does not melt or decompose at the polymer melting point of EVOH, and is in a micro-particle form; at the same time, the para position of the benzene ring and the carbon-carbon triple bond are both connected with polar groups, so that the nucleating agent as a whole is polar and can be evenly dispersed in polar EVOH. Furthermore, the polar group in the carbon-carbon triple bond, that is, R1 contains a flexible rotatable functional group, which can improve the flexibility of EVOH crystals. In addition, the organic phosphate group has the nature of flame retardancy, and the organic phosphate nucleating agent can increase the flame retardancy of EVOH, making it safer to be used in automobile fuel tanks.

[0032] The reaction in the preparation process of the nucleating agent provided by the present invention is a typical esterification reaction, wherein the reactant shown in formula A is acidic, so there is no need to add an additional acid catalyst, the preparation process is simple, the reaction conditions are not harsh, and the equipment requirements are low.

[0033] In addition, after the nucleating agent shown in Formula I provided by the present invention is mixed with EVOH, during melt extrusion, homogeneous nucleation can be induced to transform into heterogeneous nucleation. During the heterogeneous nucleation process, because of the presence of foreign matter in the EVOH melt, the crystallization rate is increased, and the free energy required to form the critical nucleus in homogeneous nucleation is reduced. At the same time, a larger number of crystal nuclei can be formed in heterogeneous nucleation, the size of the formed spherulites is reduced, and the crystallinity and crystallization temperature of EVOH are also improved. In addition, the nucleating agents R2 and R3 are polar groups with hydrogen, and can also form hydrogen bonds with the hydroxyl groups in EVOH, so that EVOH and the nucleating agent are more closely combined, so as to achieve the purpose of high nucleation efficiency and fast nucleation rate.

[0034] In conclusion, the nucleating agent provided by the present invention has a small addition amount and a wide application range, and can be applied to EVOH with an ethylene content of 10 to 90 wt %, and the obtained EVOH has excellent comprehensive performance. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] At present, the thermal stability and flexibility of EVOH prepared in the prior art are difficult to meet the use requirements at the same time. Therefore, the present invention aims to develop a nucleating agent to improve the crystallization of EVOH, optimize its gas barrier properties, mechanical properties, thermodynamic properties and haze, while taking into account its flexibility to improve the processability of EVOH and expand the application range of EVOH.

[0037] Based on this, the present invention provides a nucleating agent as shown in Formula I:

[0038] Formula I;

[0039] In the present invention, R1 is a polar group with a rotatable bond, which can be selected from -(CH2) n -OH, -OCO(CH2) m CH3, -(CH2) x -Br, -(CH2) y -F, -CH2OOCH3, -CH2CH2OOCH3, -C((CH3)2(NH2));

[0040] Wherein, n, m, x, and y are independently selected from any integer between 0 and 3, and specifically, can be selected from 0, 1, 2, or 3.

[0041] In the present invention, R2 and R3 are both polar groups carrying hydrogen, and are independently selected from OH-, -COOH, CH3COO-, -CH2COOH, -CH2NH2, -COCH3, -CH2OH, CH3CONH-, -NH2, -N-(CH3)2 or CH3-O-.

[0042] In some preferred embodiments of the present invention, the nucleating agent has a structure as shown in Formula I, wherein n is preferably 1 or 2, m is preferably 0, 1 or 2; x is preferably 2 or 3; and y is preferably 1 or 2.

[0043] Further, in some preferred embodiments of the present invention, the nucleating agent has a structure shown in Formula I, wherein the R1 is selected from -(CH2)2-OH, -OCOCH3, -(CH2)2-Br, -(CH2)2-F, -CH2OOCH3, -CH2CH2OOCH3, -C((CH3)2(NH2)).

[0044] In some specific embodiments of the present invention, the nucleating agent is selected from any one of the following formulas 1 to 3:

[0045] Formula 1; Formula 2; Formula 3.

[0046] The present invention provides a nucleating agent shown in the above formula I, which belongs to the organic phosphate compound nucleating agent among α nucleating agents, contains a benzene ring and a carbon-carbon triple bond, has good thermal stability, and ensures that in the subsequent application process of preparing EVOH, it does not melt or decompose at the polymer melting point of EVOH, and is in the form of microparticles; at the same time, the para position of the benzene ring and the carbon-carbon triple bond are both connected with polar groups, so that the nucleating agent as a whole is polar and can be evenly dispersed in polar EVOH. Furthermore, the polar group in the carbon-carbon triple bond, that is, R1 contains a flexible rotatable functional group, which can improve the flexibility of EVOH crystals.

[0047] The present invention also provides a method for preparing the above nucleating agent, which comprises the following steps:

[0048] The compound represented by formula A reacts with the compound represented by formula B in the presence of a solvent to obtain a nucleating agent represented by formula I;

[0049] Formula A; Formula B.

[0050] Specifically, in some embodiments of the present invention, Formula A includes one or more of Formulas 4 to 6; Formula B includes the compound shown in Formula 7:

[0051]

[0052] Formula 4 Formula 5 Formula 6

[0053]

[0054] Formula 7.

[0055] According to the present invention, the compound represented by formula A and the compound represented by formula B are reacted in the presence of a solvent to obtain a nucleating agent represented by formula I. In the present invention, the solvent is preferably a benzene solvent; the benzene solvent includes any one or more of benzene, toluene, xylene, trimethylbenzene or ethylbenzene. Among them, the mass ratio of the compound represented by formula A to the compound represented by formula B is generally 1:1, and can also be adjusted appropriately, such as 1.1:1, 1.2:1, 1:1.1, 1:1.2, etc. The amount of the solvent added is 200 mL. The reaction temperature is 105~130℃, preferably 110~120℃; the reaction time is 0.5~5 h, preferably 1~4 h.

[0056] In some embodiments of the present invention, the compound represented by formula A and the compound represented by formula B are preferably added to a reaction bottle in proportion, stirred, and an appropriate amount of benzene solvent is added, and stirring is continued evenly, and heated to 105-130° C. and refluxed for 20-36 h.

[0057] For example, the synthesis route of the nucleating agent shown in the above formula I can be expressed as follows:

[0058] .

[0059] In some embodiments of the present invention, after the above reaction is completed, the benzene solvent is preferably removed by rotary evaporation to obtain a solid, the solid is washed with deionized water 2 to 3 times, filtered, the solid is collected and dried at 110° C. for 24 h to obtain a dry nucleating agent.

[0060] As a preferred technical solution, the reaction equipment involved in the above reaction, including the reaction bottle, Buchner funnel, rotary evaporation system, etc. must be clean, dry and flushed with nitrogen, and the solvent must be dehydrated to avoid hydrolysis of the nucleating agent and damage to the structure.

[0061] The compound represented by formula A, the compound represented by formula B and the solvent mentioned above can be commercially available products.

[0062] The nucleating agent provided by the present invention has a reaction in the preparation process: the hydroxyl group of the phosphoric acid group in the compound shown in formula A reacts with the hydrogen of the hydroxyl group in the compound shown in formula B, which is a typical esterification reaction. In addition, the reactant shown in formula A is acidic, so there is no need to add an additional acid catalyst, the preparation process is simple, the reaction conditions are not harsh, the equipment requirements are low, and it is easy to achieve large-scale production or industrial production.

[0063] The present invention also provides an application of the nucleating agent involved in the above technical solution in the preparation of EVOH.

[0064] Specifically, the present invention provides a method for preparing EVOH, which comprises the following steps:

[0065] The nucleating agent is mixed with EVOH, dried, extruded and granulated to obtain the finished product.

[0066] In the present invention, the nucleating agent and EVOH are preferably mixed in a mass ratio of 1:50 to 1:100, preferably 1:60 to 1:90. The mixing is preferably carried out in a high-speed mixer for 5 to 100 min, preferably 10 to 80 min, and more preferably 30 to 60 min. After the two are evenly mixed, the obtained mixture is dried at 60 to 110° C. for 1 to 24 h, preferably at 80 to 100° C. for 10 to 24 h.

[0067] Then, according to the present invention, the mixture is extruded and granulated to obtain a finished product. In the present invention, the extrusion and granulation are preferably carried out in a twin-screw extruder, the extrusion temperature is 150-250°C, preferably 180-220°C, and the screw speed of the twin-screw extruder is 50-200 r / min, preferably 80-150 r / min.

[0068] It should be noted that the mass ratio of the nucleating agent to EVOH is 1:50~1:100, which shows that the amount of the nucleating agent added is relatively small. In addition, the ethylene content in EVOH can range from 10 to 90 wt%, preferably 20 to 80 wt%, which shows that the nucleating agent has a wide range of uses. Further, after testing, the obtained EVOH has excellent comprehensive performance. Therefore, the nucleating agent provided by the present invention solves the problems currently faced in the preparation of EVOH.

[0069] The present invention has no particular limitation on the preparation method of the EVOH, and the preparation method can be carried out according to the technical means well known to those skilled in the art.

[0070] Exemplarily, the preparation method of EVOH comprises the following steps:

[0071] (1) Preparation of EVA by free radical polymerization of ethylene and vinyl acetate (VAc)

[0072] Specific steps: Under the protection of high-purity N2, VAc, initiator and solvent are mixed in a certain proportion, and the clarified solution is transferred into a reactor with a polytetrafluoroethylene liner, and filled with ethylene of a certain pressure. After the pressure stabilizes, the circulation pump is turned on for heating, and the target polymerization temperature is reached, and the timing is started. After a period of polymerization, the material is taken out while hot, and vacuum dried at 60°C for 24 hours to remove volatiles to obtain a transparent EVA elastomer for retention.

[0073] The reactor involved, including the lining of the reactor, must be clean, dry and flushed with nitrogen; VAc is distilled under reduced pressure to remove the inhibitor and stored in a sealed state at 10°C; the initiator is purified by recrystallization, vacuum dried, protected from light, and stored in a sealed state at 10°C. The solvent needs to be dehydrated by molecular sieve. The initiator can be an azo initiator or a peroxide compound initiator, and can be an organic initiator or an inorganic initiator, including any one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN), dibenzoyl peroxide (BPO), diethylhexyl peroxydicarbonate (EHP), potassium persulfate, ammonium persulfate or hydroperoxide. The solvent includes any one or more of ether, methanol, ethanol, tert-butyl alcohol, dimethyl carbonate (DMC), tetrahydrofuran, petroleum ether, acetone or hexane.

[0074] In some embodiments of the present invention, the ratio of VAc, initiator, and solvent (V:m:V) is (1-100):(1-100):(1-100), preferably (1-40):(1-30):(1-50), and specifically can be 30:10:50, 20:20:60, 10:30:60, or 40:10:50, etc. Wherein, V represents volume in mL, m represents mass in g; ethylene pressure is 0.01-10 MPa, preferably 0.1-5 MPa; polymerization temperature is 60-100°C, preferably 70-90°C; polymerization time is 0.5-10 h, preferably 2-8 h. The ethylene, VAc, solvent, and initiator involved are all commercially available.

[0075] The substances and their proportions, temperature, pressure and time involved in the above scheme can be adjusted as needed, and will not be described in detail to avoid complexity.

[0076] (2) Preparation of EVOH by alcoholysis of EVA

[0077] The specific steps are as follows: the EVA obtained in step (1), the alkaline catalyst and the solvent are stirred and mixed in a three-necked flask in a certain proportion, and after alcoholysis at a certain temperature for a period of time, an acid solution of a certain concentration is added dropwise to the mixed solution, and the solvent is the same as the solvent used for alcoholysis, and the reactants are neutralized until the pH is 7. Finally, the reactants are transferred to cold water, filtered, and the filter cake is washed three times with anhydrous ethanol to remove excess water, and vacuum dried at 100°C overnight to obtain the final product EVOH, which is retained for future use.

[0078] The reactor tools involved, including the reaction bottle, Buchner funnel, etc., must be clean, dry and flushed with nitrogen. The solvent needs to be dehydrated. The solvent includes any one or more of ether, methanol, ethanol, tert-butyl alcohol, dimethyl carbonate (DMC), tetrahydrofuran, petroleum ether, acetone or hexane. The alkaline catalyst includes any one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, calcium hydroxide, sodium carbonate or potassium bicarbonate. The ratio of EVA, alkaline catalyst, and solvent (m:m:V) is (1~10):(1~10):(1~10), preferably (1~4):(1~3):(1~5), specifically 4:1:5, 3:2:5, 2:3:5 or 4:1:5, etc. V represents volume in mL, and m represents mass in g. The temperature of alcoholysis is 40~80℃, preferably 50~60℃; the time of alcoholysis is 0.5~10 h, preferably 2~6 h. The concentration of the acidic solution is 0.01~10 mol / L, preferably 0.1~8 mol / L. The solute in the acidic solution includes organic acids and inorganic acids, specifically selected from any one or more of acetic acid, boric acid, and hydrochloric acid. The solvent of the acidic solution includes any one or more of ether, methanol, ethanol, tert-butanol, dimethyl carbonate (DMC), tetrahydrofuran, petroleum ether, acetone or hexane. It should be noted that the above-mentioned solvents, acidic solutions, anhydrous ethanol, alkaline catalysts, etc. are all commercially available.

[0079] The substances and their proportions, temperature, pressure and time involved in the above scheme can be adjusted as needed, and will not be described in detail to avoid complexity.

[0080] In order to further illustrate the present invention, the following examples are used to explain in detail. The experimental raw materials used in the following examples of the present invention are all common commercial products. The "V" involved in the following represents volume, the unit is mL, and the "m" represents mass, the unit is g. Example 1

[0081] 1.14 g of acetylene dimethyl ester dimethanol and 2.21 g of 4-hydroxyphenoxy-4-hydroxyphenyl-phosphoric acid were added to a reaction bottle, stirred, and 200 mL of toluene was added, and the stirring was continued evenly. The mixture was heated to 110°C and refluxed for 2 h. The toluene was removed by rotary evaporation to obtain a solid. The solid was washed three times with deionized water, filtered, and the solid was collected and dried at 110°C for 24 h to obtain a 4-hydroxyphenoxy-4-hydroxyphenyl-3-acetylene dimethyl ester-phosphate nucleating agent (whose structural formula is shown in Formula 1), which was sealed and retained.

[0082] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V:m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3 MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After polymerization for 2 h, the material was taken out while hot and vacuum dried at 60°C for 24 h to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0083] EVA, sodium hydroxide and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 h, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed with anhydrous ethanol three times, excess water was removed, and dried at 100°C overnight to obtain EVOH, which was retained.

[0084] The above-mentioned 4-hydroxyphenoxy-4-hydroxyphenyl-3-ethynyl dimethyl ester-phosphate nucleating agent and EVOH are mixed in a high-speed mixer at a mass ratio of 1:100 for 60 min, dried at 110°C for 24 h, and then the mixture is put into a co-rotating twin-screw extruder at an extrusion temperature of 220°C and a screw speed of 150 r / min. Drying at 110°C for 24 h, EVOH doped with a small amount of nucleating agent is obtained, which is the final product. Example 2

[0085] 1.14 g of acetylene dimethyl ester dimethanol and 1.20 g of 4-aminophenoxy-4-aminophenyl-phosphoric acid were added to a reaction bottle, stirred, and 200 mL of a benzene solvent was added, and the stirring was continued evenly. The mixture was heated to 110°C and refluxed for 2 h. Toluene was removed by rotary evaporation to obtain a solid. The solid was washed three times with deionized water, filtered, and the solid was collected and dried at 110°C for 24 h to obtain a 4-aminophenoxy-4-aminophenyl-3-acetylene dimethyl ester-phosphate nucleating agent (whose structural formula is shown in Formula 2), which was sealed and retained.

[0086] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V:m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After the polymerization for 2 hours, the material was taken out while hot and vacuum dried at 60°C for 24 hours to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0087] EVA, sodium hydroxide and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 h, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed with anhydrous ethanol three times, excess water was removed, and dried at 100°C overnight to obtain EVOH, which was retained.

[0088] The above-mentioned 4-aminophenoxy-4-aminophenyl-3-ethynyl dimethyl ester-phosphoric acid nucleating agent and EVOH are mixed in a high-speed mixer at a mass ratio of 1:100 for 60 min, dried at 110°C for 24 h, and then the mixture is put into a co-rotating twin-screw extruder at an extrusion temperature of 220°C and a screw speed of 150 r / min. Drying at 110°C for 24 h, EVOH doped with a small amount of nucleating agent is obtained, which is the final product. Example 3

[0089] 1.14 g of acetylene dimethyl ester dimethanol and 1.20 g of 4-methoxyphenoxy-4-methoxyphenyl-phosphoric acid were added to a reaction bottle, stirred, and 200 mL of a benzene solvent was added, and the stirring was continued to be uniform. The mixture was heated to 110° C. and refluxed for 2 h. Toluene was removed by rotary evaporation to obtain a solid. The solid was washed three times with deionized water, filtered, and the solid was collected and dried at 110° C. for 24 h to obtain a 4-methoxyphenoxy-4-methoxyphenyl-3-acetylene dimethyl ester-phosphate nucleating agent (whose structural formula is shown in Formula 3), which was sealed and retained.

[0090] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V:m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3 MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After polymerization for 2 h, the material was taken out while hot and vacuum dried at 60°C for 24 h to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0091] EVA, sodium hydroxide and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 h, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed with anhydrous ethanol three times, excess water was removed, and dried at 100°C overnight to obtain EVOH, which was retained.

[0092] The above-mentioned 4-methoxyphenoxy-4-methoxyphenyl-3-ethynyl dimethyl ester-phosphate nucleating agent and EVOH are mixed in a high-speed mixer at a mass ratio of 1:100 for 60 min, dried at 110°C for 24 h, and then put into a co-rotating twin-screw extruder at an extrusion temperature of 220°C, a screw speed of 150 r / min, and dried at 110°C for 24 h to obtain EVOH doped with a small amount of nucleating agent, which is the final product. Example 4

[0093] 1.14 g of acetylene dimethyl ester dimethanol and 1.20 g of 4-hydroxyphenoxy-4-hydroxyphenyl-phosphoric acid were added to a reaction bottle, stirred, and 200 mL of a benzene solvent was added, and the stirring was continued to be uniform. The mixture was heated to 110° C. and refluxed for 2 h. Toluene was removed by rotary evaporation to obtain a solid. The solid was washed three times with deionized water, filtered, and the solid was collected and dried at 110° C. for 24 h to obtain a 4-hydroxyphenoxy-4-hydroxyphenyl-3-acetylene dimethyl ester-phosphate nucleating agent (whose structural formula is shown in Formula 1), which was sealed and retained.

[0094] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V:m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3 MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After polymerization for 2 h, the material was taken out while hot and vacuum dried at 60°C for 24 h to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0095] EVA, sodium hydroxide and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 hours, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed with anhydrous ethanol for 3 times to remove excess water, and dried at 100°C overnight to obtain EVOH, which was retained.

[0096] The above-mentioned 4-hydroxyphenoxy-4-hydroxyphenyl-3-ethynyl dimethyl ester-phosphate nucleating agent and EVOH are mixed in a high-speed mixer at a mass ratio of 1:75 for 60 min, dried at 110°C for 24 h, and then the mixture is put into a co-rotating twin-screw extruder at an extrusion temperature of 220°C, a screw speed of 150 r / min, and dried at 110°C for 24 h to obtain EVOH doped with a small amount of nucleating agent, which is the final product. Example 5

[0097] 1.14 g of acetylene dimethyl ester dimethanol and 1.20 g of 4-methoxyphenoxy-4-methoxyphenyl-phosphoric acid were added to a reaction bottle, stirred, and 200 mL of a benzene solvent was added, and the stirring was continued to be uniform. The mixture was heated to 110° C. and refluxed for 2 h. Toluene was removed by rotary evaporation to obtain a solid. The solid was washed three times with deionized water, filtered, and the solid was collected and dried at 110° C. for 24 h to obtain a 4-methoxyphenoxy-4-methoxyphenyl-3-acetylene dimethyl ester-phosphate nucleating agent (whose structural formula is shown in Formula 3), which was sealed and retained.

[0098] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V:m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After the polymerization for 2 hours, the material was taken out while hot and vacuum dried at 60°C for 24 hours to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0099] EVA, sodium hydroxide and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 h, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed with anhydrous ethanol three times, excess water was removed, and dried at 100°C overnight to obtain EVOH, which was retained.

[0100] The above-mentioned 4-methoxyphenoxy-4-methoxyphenyl-3-ethynyl dimethyl ester-phosphate nucleating agent and EVOH are mixed in a high-speed mixer at a mass ratio of 1:75 for 60 min, dried at 110°C for 24 h, and then the mixture is put into a co-rotating twin-screw extruder at an extrusion temperature of 220°C, a screw speed of 150 r / min, and dried at 110°C for 24 h to obtain EVOH doped with a small amount of nucleating agent, which is the final product.

[0101] Comparative Example 1

[0102] Under the protection of high-purity N2, VAc, AIBN and anhydrous methanol were mixed in a ratio of 30:10:50 (V: m:V). The clarified solution was transferred into a reactor with a polytetrafluoroethylene liner and filled with 3MPa of ethylene. After the pressure stabilized, the circulating pump was turned on for heating. The polymerization temperature was 60°C. After polymerization for 2 h, the material was taken out while hot and vacuum dried at 60°C for 24 h to remove volatiles to obtain a transparent EVA elastomer, which was retained and tested.

[0103] EVA, NaOH and methanol were stirred and mixed in a three-necked flask at a ratio of 4:1:5 (m:m:V), and after alcoholysis at 65°C for 2 hours, 1 mol / L acetic acid / methanol solution was added dropwise to the mixed solution to neutralize the reactants until pH = 7. Finally, the reactants were transferred to cold water, washed three times with water to remove water-soluble impurities in the solution, and then washed three times with anhydrous ethanol to remove excess water. The mixture was dried at 100°C overnight to obtain the final product EVOH, which was retained and tested.

[0104] Performance Testing

[0105] The test method is as follows:

[0106] GPC tests Mn and PDI, and the test method is as follows: at 65°C, 1 mL of DMF and 2 mg of EVOH were dissolved for 1 h to obtain a clear solution, and Waters GPC 1515 was used to test Mn and PDI. The test temperature was 30°C, the mobile phase was DMF, the mobile phase flow rate was 1.0 mL / min, and polystyrene was used to obtain the standard curve.

[0107] DSC Test T m , T c , T g The test method is as follows: 5 mg EVOH sample is placed in an aluminum pan in a nitrogen atmosphere (50 mL

[0108] / min), from 25℃ to 200℃, and kept at 200℃ for 30min, with a heating rate of 10℃ / min. This stage is the first stage, the purpose is to eliminate the thermal history of the material, and naturally cool to room temperature. This is the second stage to measure T c Finally, the temperature rises from room temperature to 200℃, which is the third stage. T g and T m , equipment model: METTLER TOLEDO.

[0109] NMR test of alcoholysis degree: using BRUKER AVANCE 400M 1H spectrum, tetramethylsilane as internal standard (δ = 0.0 ppm), 10 mg EVOH was dissolved in 1 mL DMSO-d6, the dissolution temperature was 85 ° C, until a clear solution was obtained, injected into a quartz tube, tested, the obtained H spectrum was analyzed, and the peak area of ​​δ = 3.5 ~ 3.8 ppm (-OH group after VAC alcoholysis) was integrated to obtain I (VOH) , integrate the peak area of ​​δ = 2.0 ppm (-CH3 in VAC) to obtain I (V-CH3) , alcoholysis degree = I (VOH) *100% / (I (VOH) + I (V-CH3) ).

[0110] Brugger GTT, a differential pressure gas permeability tester, tests oxygen permeability. Test standard: GB / T 1038, temperature: 23°C, relative humidity: 51%, test area: 5 cm 2 , test thickness 80 μm.

[0111] The universal testing machine tests the impact strength, tensile strength and elongation at break. The test standard is GB / T 1040.1-2006. The injection molding conditions of the spline are GB / T 17037.1.

[0112] Haze, test reference standard GB T 2410-2008.

[0113] The test results are shown in Tables 1 and 2 below:

[0114] Table 1 Comparison of basic properties of EVOH

[0115] Table 2 Comparison of EVOH mechanical properties

[0116] The terms involved in Table 1 and Table 2 above are explained as follows:

[0117] 1. Number average molecular weight (Mn): The molecular weight is measured based on the number fraction. The number average molecular weight is equal to the molecular weight of each component multiplied by the mole fraction of each component.

[0118] 2. Polydispersity index (PDI): polymer molecular weight distribution. The larger the PDI, the wider the molecular weight distribution; the smaller the PDI, the more uniform the molecular weight distribution.

[0119] 3. Crystallization temperature (T c ): refers to the temperature required for a substance to transform from a liquid to a crystal;

[0120] 4. Melting temperature (T m ): temperature at which melting occurs;

[0121] 5. Glass transition temperature (T g ): The temperature at which the glassy state changes to the highly elastic state;

[0122] 6. Alcoholysis degree: the percentage of hydroxyl groups in the product obtained after alcoholysis to the original groups;

[0123] 7. Oxygen transmission rate (O2GTR): The volume of oxygen that passes through a unit area of ​​a material such as a plastic film per unit time at a constant temperature and unit pressure difference when the transmission is stable;

[0124] 8. Impact strength: an indicator that reflects a material's ability to resist impact (brittleness and toughness);

[0125] 9. Tensile strength: the maximum stress value that the material can withstand before breaking;

[0126] 10. Elongation at break: the ratio of the displacement value of the specimen at break to the original length, expressed as a percentage (%);

[0127] 11. Crystallinity: The proportion of the crystalline region in the polymer, expressed as a percentage (%). The higher the crystallinity, the more regular the molecular chain arrangement and the higher the melting point.

[0128] 12. Haze: The percentage (%) of the transmitted light intensity that deviates from the incident light by more than 2.5° to the total transmitted light intensity. The greater the haze, the lower the gloss and transparency of the film.

[0129] From the data in Table 1 and Table 2, it can be seen that the addition of nucleating agent does not have a significant effect on the molecular weight of EVOH, but because the nucleating agent can make the formed grains finer, the haze and mechanical properties of EVOH are significantly improved. In addition, the nucleating agent can also increase the crystallinity of EVOH, which significantly reduces its oxygen permeability and greatly improves its barrier properties.

[0130] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nucleating agent as shown in formula I: Formula I; in, R1 is selected from -(CH2) n -OH, -OCO(CH2) m CH3, -(CH2) x -Br, -(CH2) y -F, -CH2OOCH3, -CH2CH2OOCH3, -C((CH3)2(NH2)); n, m, x, and y are independently selected from any integer between 0 and 3; R2 and R3 are each independently selected from OH-, -COOH, CH3COO-, -CH2COOH, -CH2NH2, -COCH3, -CH2OH, CH3CONH-, -NH2, -N-(CH3)2 or CH3-O-.

2. The nucleating agent according to claim 1, characterized in that The n is 1 or 2; the m is 0, 1 or 2; the x is 2 or 3; and the y is 1 or 2.

3. The nucleating agent according to claim 1 or 2, characterized in that The nucleating agent is selected from any one of the following formulas 1 to 3: Formula 1; Formula 2; Formula 3.

4. A method for preparing a nucleating agent as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: The compound represented by formula A reacts with the compound represented by formula B in the presence of a solvent to obtain a nucleating agent represented by formula I; Formula A; Formula B.

5. The preparation method according to claim 4, characterized in that: The solvent is selected from benzene solvents; The benzene solvent includes any one or more of benzene, toluene, xylene, trimethylbenzene or ethylbenzene.

6. The preparation method according to claim 4 or 5, characterized in that: The reaction temperature is 105-130° C. and the reaction time is 0.5-5 h.

7. Use of the nucleating agent according to any one of claims 1 to 3 or the nucleating agent prepared by the preparation method according to any one of claims 4 to 6 in the preparation of EVOH.

8. A method for preparing EVOH, characterized in that: The following steps are involved: After the nucleating agent is mixed with EVOH, it is dried, extruded, and granulated to obtain the finished product; The nucleating agent is the nucleating agent according to any one of claims 1 to 3 or the nucleating agent prepared by the preparation method according to any one of claims 4 to 6.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the nucleating agent to EVOH is 1:50-1:100; The ethylene content in the EVOH is 10-90 wt %.

10. The preparation method according to claim 8 or 9, characterized in that: The mixing time is 5 to 100 min; The drying temperature is 60-110°C and the drying time is 1-24 h; The extrusion temperature is 150-250°C.

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