Nucleating agent and composite processing aid for reinforcing and increasing the permeability of polyethylene film material

Abstract

The application belongs to the technical field of polyethylene film material production and application, and particularly relates to a nucleating agent and a composite processing aid for increasing rigidity and transparency of polyethylene film material. The nucleating agent is used to accelerate the crystallization period and form crystallization due to the short branched chain wrapping the crystal nucleus, so that the active branched chain is greatly reduced, so that the polyethylene molecules are difficult to become excited state or cause the destruction of chemical bonds to cause free radical chain reaction under light irradiation, thereby improving the aging resistance of the polyethylene film material. At the same time, the shortening of the crystallization period makes the crystallization faster, the crystal nucleus smaller and the distribution more uniform, thereby obviously improving the transparency and rigidity of the film material. In addition, the mutual coordination between the nucleating agent and other additives further improves the film forming performance of the polyethylene film material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyethylene film material production and application, and particularly relates to a nucleating agent for increasing rigidity and transparency and a composite processing aid in polyethylene film material. BACKGROUND

[0002] Polyethylene is widely used in the preparation of various film materials due to its good comprehensive properties such as flexibility, transparency and processing performance. The raw material used for the composite outer packaging film is mainly a blend of LDPE (low-density polyethylene) and LLDPE (linear low-density polyethylene). The composite packaging film prepared from the above composition has good comprehensive properties in terms of flexibility, processing performance, etc., but still has deficiencies in terms of heat aging resistance, tear resistance, impact strength, etc. In actual use, due to the deficiencies in the above properties, the composite packaging film may be damaged and broken by external force due to insufficient material strength, poor wear resistance and poor puncture resistance.

[0003] At the same time, optical performance is also one of the evaluation indexes of the film. Better optical performance can improve the appearance quality of the film. When used as a packaging film, the user requires low haze and high clarity. In addition, another main application environment of LLDPE is outdoor shed film. For this, on the one hand, the transparency of the shed film needs to be improved so that the shed film does not affect the entry of light during use, and on the other hand, due to the long-term outdoor application environment, the shed film also has certain requirements for aging resistance and rigidity. Therefore, how to improve the heat aging resistance, tear resistance, impact strength, etc. of the composite outer packaging film is a problem to be solved at present. SUMMARY

[0004] The application provides a nucleating agent for increasing rigidity and transparency in polyethylene film material, which can significantly improve the above indexes.

[0005] In order to achieve the above purpose, the technical scheme adopted by the application is as follows: the application provides a nucleating agent for increasing rigidity and transparency in polyethylene film material, which comprises a main nucleating agent and an auxiliary nucleating agent, wherein the structural formula of the main nucleating agent is shown as formula (1):

[0006]

[0007] Wherein, R1, R2, R3 can be selected from hydrogen, C2-C5 alkyl, C2-C5 alkoxy, hydroxyl and at least one selected from hydroxyl, one group selected from C2-C5 alkoxy; R4, R5, R6 can be selected from hydrogen, C2-C5 alkyl, C2-C5 alkoxy and at least one selected from C2-C5 alkoxy; M is a metal, which can be selected from any one of Ca, Mg, Al, Zn;

[0008] The auxiliary nucleating agent has a structural formula as shown in formula (2):

[0009]

[0010] Wherein, R7, R8 can be selected from C 12 -C 18 Straight chain alkyl, sodium ion and at least one is sodium ion;

[0011] The mass ratio between the main nucleating agent and the auxiliary nucleating agent is 2-8:8-2.

[0012] The application further provides a composite processing aid for polyethylene film material, which comprises an antioxidant, a light stabilizer, a lubricant, an antistatic agent, an opening agent and a nucleating agent, wherein the nucleating agent is the nucleating agent provided above.

[0013] As preferred, the antioxidant comprises at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 622 and antioxidant 626.

[0014] As preferred, the light stabilizer is at least one of ultraviolet absorber UV-328, light stabilizer 944 and light stabilizer 770.

[0015] As preferred, the lubricant is at least one of stearic acid, stearic acid monoglyceride, oleic acid, oleic acid monoglyceride, calcium stearate and zinc stearate.

[0016] As preferred, the antistatic agent is at least one of lauryl trimethyl ammonium chloride, N-(3-alkoxy-2-hydroxypropyl) monoethanolamine and hydroxyethyl alkyl amine.

[0017] As preferred, the opening agent comprises at least one of silicon dioxide and hydrotalcite.

[0018] As preferred, the addition amount of the nucleating agent is 200-5000 ppm; the addition amount of the antioxidant is 1000-2000 ppm; the addition amount of the light stabilizer is 500-1000 ppm; the addition amount of the lubricant is 500-1000 ppm; the addition amount of the antistatic agent is 500-1000 ppm; and the addition amount of the opening agent is 200-800 ppm.

[0019] Preferably, the particle size D50 of the opening agent is 10um < D50 < 20um.

[0020] Compared with the prior art, the application has the advantages and positive effects that the application provides a nucleating agent for increasing rigidity and transparency and a composite processing aid, the setting of the nucleating agent accelerates the crystallization period and forms crystals due to the wrapping of short branch chains around the crystal nucleus, so that the number of active branch chains is greatly reduced, so that it is difficult for the polyethylene molecules to become excited or to cause the destruction of chemical bonds to cause free radical chain reactions under light irradiation, thereby improving the aging resistance of the polyethylene film material, at the same time, the shortening of the crystallization period makes the crystallization faster, the crystal nucleus smaller and the distribution uniform, thereby significantly improving the transparency and rigidity of the film material. In addition, the mutual coordination between the nucleating agent and other aids further improves the film forming performance of the polyethylene film material. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned purposes, features and advantages of the application, the application will be further described below in combination with examples. It should be noted that the examples and features in the examples of the present application can be combined with each other without conflict.

[0022] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the present application is not limited to the specific embodiments disclosed in the following description.

[0023] Polyethylene belongs to semi-crystalline polymer materials, the morphology and content of the crystal region and the amorphous region have a very key influence on the performance of polyethylene. Generally, during the polymer processing and cooling process, a crystallization process is accompanied, which is divided into two stages of nucleation and growth. The nucleation process refers to the formation of crystal nucleus by the molecular chain overcoming the critical nucleation work, and the growth process refers to the growth of the molecular chain on the formed crystal nucleus.

[0024] Currently, nucleating agents for polyethylene can be divided into traditional organic nucleating agents, inorganic nano nucleating agents, liquid crystal organic polymer nucleating agents and ultra-high molecular weight polyethylene (UHMWPE) nucleating agents. These nucleating agents have different characteristics after polyethylene film formation, for example, the transparency of the product prepared by blending traditional organic nucleating agents with polyethylene is improved, but the mechanical properties are not much different. The tensile strength of the product prepared by blending inorganic nano nucleating agents such as carbon nanotubes with polyethylene is increased from 30 MPa to more than 100 MPa. However, other properties change little. Liquid crystal organic polymer nucleating agents have good nucleation effect in polyethylene, but their application is less due to the following reasons: the synthesis steps of liquid crystal organic polymer are more and more difficult; secondly, the melting point of liquid crystal organic polymer is higher than 260℃, which is close to the decomposition temperature of polyethylene, so it can only be uniformly dispersed in the polyethylene matrix by solution blending with polyethylene. Although UHMWPE can be used as a nucleating agent for polyethylene, it also has certain limitations. It is not easy to blend UHMWPE with polyethylene, and it is almost impossible to completely disperse uniformly under normal processing conditions. However, even if the SEM shows that UHMWPE is not completely uniformly distributed, the DSC characterization still finds that the onset temperature of crystallization is improved, indicating that the partial dispersion of UHMWPE in HDPE can also have a certain nucleation effect. In addition to considering the nucleation effect, the existence of UHMWPE agglomeration in HDPE will also affect the performance of the product.

[0025] Therefore, in order to adapt to industrial use, at the same time, to achieve the purpose of comprehensively changing the film forming properties of polyethylene, in the present embodiment, the rigidifying and transparency-improving nucleating agent for polyethylene film material includes a main nucleating agent and an auxiliary nucleating agent, wherein the structural formula of the main nucleating agent is shown as formula (1):

[0026]

[0027] wherein R1, R2, R3may be selected from hydrogen, C2-C5alkyl, C2-C5alkoxy, hydroxyl and at least one selected from hydroxyl, one group selected from C2-C5alkoxy; R4, R5, R6may be selected from hydrogen, C2-C5alkyl, C2-C5alkoxy and at least one selected from C2-C5alkoxy; M is a metal, which can be selected from any one of Ca, Mg, Al and Zn;

[0028] The structural formula of the auxiliary nucleating agent is shown as formula (2):

[0029]

[0030] wherein R7, R8may be selected from C 12 -C 18linear alkyl, sodium ion and at least one sodium ion.

[0031] The applicant found that, due to the molecular structure of the main nucleating agent containing -OH and alkoxy, -OH has affinity to LLDPE and other additives, on the one hand, it can make the nucleating agent and other additives can be well dispersed in the LLDPE resin particles, and play their respective role effect; on the other hand, in the process of LLDPE processing melt-cooling crystallization, the benzene ring structure containing -OH fully contacts the resin molecular chain segment, and provides a large number of nucleation sites for the LLDPE molecular structure, so as to improve the crystallinity of LLDPE, and the rigidity of the film material is improved; at the same time, the main nucleating agent and the auxiliary nucleating agent are both ionic nucleating agents, and they have good melt dispersibility, and the applicant unexpectedly found that the combined use of the main nucleating agent and the auxiliary nucleating agent can improve the crystallization temperature of LLDPE, so that the LLDPE can crystallize quickly at high temperature, so as to obtain more crystalline regions and improve the crystallinity; and the long chain alkyl on the main nucleating agent and the auxiliary nucleating agent provides more winding area for the short chain of LLDPE, so that the tensile property of the film material is improved.

[0032] Example 1, the polyethylene film material provided by the composite processing aid of the embodiment

[0033] The structural formula of the main nucleating agent is as follows:

[0034]

[0035] R1 is C5H 11 O-, R2 is -OH, R3 is C3H7-, R4 is H-, R5 is C3H7O-, R6 is C3H7O-, and the metal is Ca 2+ .

[0036]

[0037] R7 is C 12 H 25 , R8 is Na.

[0038] The antioxidant is antioxidant 1010; the light stabilizer is a mixture of ultraviolet absorber UV-328 and light stabilizer 944 in a mass ratio of 1:1; the lubricant is oleic acid monoglyceride; the antistatic agent is a mixture of lauryl trimethyl ammonium chloride and N-(3-alkoxy-2-hydroxypropyl) monoethanolamine in a mass ratio of 1:1; and the opening agent is silicon dioxide. The addition amount of the nucleating agent is 200 ppm; the addition amount of the antioxidant is 2000 ppm; the addition amount of the light stabilizer is 500 ppm; the addition amount of the lubricant is 500 ppm; the addition amount of the antistatic agent is 1000 ppm; and the addition amount of the opening agent is 200 ppm.

[0039] The above antioxidant, light stabilizer, lubricant, antistatic agent, opening agent and nucleating agent are added to the LLDPE resin particles in a suitable proportion, mixed in a high-speed mixer for 20-50 min to ensure uniform mixing of each additive, and then placed in a film blowing machine for film blowing processing and molding;

[0040] LLDPE: Qilu Petrochemical Company, brand: 7042

[0041] The film blowing machine is selected from Hangzhou Leipu Technology Co., Ltd., model: LB-016 laboratory film blowing machine. The temperature of each zone is set as follows:

[0042] Zone 1: 175°C Zone 2: 180°C Zone 3: 175°C Zone 4: 170°C Zone 5: 180°C The nucleating agent is produced by Shanghai Qilin New Material Co., Ltd., and other additives are commercially available. After purchasing the raw materials, they are processed. It should be noted that the particle size of the opening agent silicon dioxide and hydrotalcite is limited to 10um <D50 <20um. If the particle size is too small, agglomeration will occur during mixing, resulting in uneven particle size and uneven dispersion of the opening agent during LLDPE processing, unstable opening. If the particle size is too large, because the opening agent is an inorganic additive with a high melting point, it will not melt at this processing temperature, causing large particles of the opening agent to float on the surface of the film material, resulting in white or transparent small particles on the surface of the film material, called crystal points, affecting the product quality of the film material.

[0043] Example 2 provides a composite processing aid for polyethylene film material

[0044] The structural formula of the main nucleating agent is as follows:

[0045]

[0046] R1 is C5H 11 O-, R2 is HO-, R3 is C5H 11 O-, R4 is C3H7O-, R5 is C3H7O-, R6 is C3H7O-, and the metal is Al 3+ .

[0047]

[0048] R7 is Na, and R8 is Na.

[0049] The antioxidant is a mixture of antioxidant 168 and antioxidant 626 in a mass ratio of 1:2; the light stabilizer is light stabilizer 770; the lubricant is a mixture of stearic acid and stearic acid monoglyceride in a mass ratio of 1:1; the antistatic agent is hydroxyethyl alkyl amine, and the opening agent is silicon dioxide. The additive amount of the nucleating agent is 2500 ppm; the additive amount of the antioxidant is 1500 ppm; the additive amount of the light stabilizer is 800 ppm; the additive amount of the lubricant is 800 ppm; the additive amount of the antistatic agent is 500 ppm; and the additive amount of the opening agent is 500 ppm.

[0050] The preparation method is the same as that of Example 1, and thus is not described in detail herein.

[0051] Example 3, the composite processing aid for polyethylene film material

[0052] The structural formula of the main nucleating agent is as follows:

[0053]

[0054] R1 is C2H5O-, R2 is HO-, R5 is C5H 11 O-, and the metal is Mg 2+ .

[0055]

[0056] R7 is Na, and R8 is Na.

[0057] The antioxidant is antioxidant 1076; the light stabilizer is a mixture of ultraviolet absorber UV-328 and light stabilizer 770 in a mass ratio of 1:1; the lubricant is a mixture of oleic acid, calcium stearate and zinc stearate in a mass ratio of 1:1:1; the antistatic agent is a mixture of lauryl trimethyl ammonium chloride and silicon dioxide and hydrotalcite in a mass ratio of 1:1. The additive amount of the nucleating agent is 5000 ppm; the additive amount of the antioxidant is 2000 ppm; the additive amount of the light stabilizer is 500 ppm; the additive amount of the lubricant is 500 ppm; the additive amount of the antistatic agent is 1000 ppm; and the additive amount of the opening agent is 800 ppm. The preparation method is the same as that of Example 1, and thus is not described in detail herein.

[0058] Example 4, the composite processing aid for polyethylene film material

[0059] The structural formula of the main nucleating agent is as follows:

[0060]

[0061] R1 is C4H9O-, R2 is HO-, R3 is HO-, R4 is C2H5-, R5 is C4H9O-, R6 is C2H5-, and the metal is Zn2+ .

[0062]

[0063] R7is C 18 H 37 , R8is Na.

[0064] Antioxidant is a mixture of antioxidant 1076, antioxidant 622 and antioxidant 626 in a mass ratio of 1:1:1; light stabilizer is a mixture of light stabilizer 944 and light stabilizer 770 in a mass ratio of 3:1; lubricant is a mixture of stearic acid monoglyceride and oleic acid in a mass ratio of 1:2; antistatic agent is a mixture of lauryl trimethyl ammonium chloride, opening agent is a mixture of silica and hydrotalcite in a mass ratio of 1:1. Among them, the addition amount of nucleating agent is 4000ppm; antioxidant 1600ppm; light stabilizer 700ppm; lubricant 600ppm; antistatic agent 8000ppm; opening agent 500ppm. The preparation method is the same as example 1, and therefore is not described in detail here.

[0065] Comparative experiment:

[0066] Comparative example 1

[0067] The difference from example 1 is only that the main nucleating agent and auxiliary nucleating agent are not added;

[0068] Comparative example 2

[0069] The difference from example 1 is only that the main nucleating agent is added, and the auxiliary nucleating agent is not added;

[0070] Comparative example 3

[0071] The difference from example 1 is only that the auxiliary nucleating agent is added, and the main nucleating agent is not added;

[0072] Comparative example 4

[0073] The difference from example 1 is only that the opening agent silica is 5um

[0074] Comparative example 5

[0075] The difference from example 1 is only that the opening agent silica is 20um

[0076] Comparative example 6

[0077] The difference from example 1 is only that the addition amount of nucleating agent is 100ppm; antioxidant 800ppm; light stabilizer 300ppm; lubricant 300ppm; antistatic agent 300ppm; opening agent 100ppm;

[0078] Comparative Example 7

[0079] The difference from Example 1 is only that the addition amount of nucleating agent is 5500 ppm; the addition amount of antioxidant is 2500 ppm; the light stabilizer is 1500 ppm; the lubricant is 1500 ppm; the antistatic agent is 1500 ppm; the opening agent is 1000 ppm;

[0080] The above components of antioxidants, light stabilizers, lubricants, antistatic agents, opening agents and nucleating agents in the examples and comparative examples are added to the LLDPE resin particles according to the addition amount, mixed in a high-speed mixer for 20-50 min to ensure uniform mixing of each additive, and then placed in a film blowing machine for film blowing processing and molding;

[0081] LLDPE: Qilu Petrochemical Company, brand: 7042

[0082] The film blowing machine selected is: Hangzhou Leipu Technology Co., Ltd., model: LB-016 laboratory film blowing machine. The temperature settings of each temperature zone are as follows:

[0083] Zone 1: 175°C Zone 2: 180°C Zone 3: 175°C Zone 4: 170°C Zone 5: 180°C The film material blown by the above film blowing machine should be conditioned in an environment with a temperature of (23±2) °C and a relative humidity of (50±5) % before testing, according to the provisions of GB / T 2918-1998. The conditioning time should not be less than 40 h; the sample is tested.

[0084] The dart impact strength test is carried out according to the GB / T 9639.1-2008 (B method) standard; the haze test is carried out according to the GB / T 2410-2008 standard; the tensile strength test is carried out according to the GB / T 16578.2-2009 standard; the friction coefficient test is carried out according to the GB / T 10006-2021 standard, and the appearance / crystal point condition is tested by visual method; the results are as follows:

[0085] Table 1: Experimental results

[0086]

[0087] From the above experimental results, it can be clearly known that the use of nucleating agent plays an important role in improving various indexes of the film material, when the amount of nucleating agent is too small, the nucleating agent provides relatively few nucleation sites, resulting in low crystallinity of LLDPE, and because there are few crystal nuclei, the molecular chain segments of LLDPE move around the few crystal nuclei to wrap the crystal nuclei, so that the crystal nuclei are too large, the refraction of light increases, and the haze decreases; when the amount of nucleating agent is too much, the excess crystal cells are distributed in the molecular structure of LLDPE, in the process of rapid cooling crystallization, the small molecular chain segments cannot completely wrap the crystal nuclei, resulting in incomplete crystal type crystallization, the crystal nuclei produce refraction of light, resulting in the decrease of light transmittance and the increase of haze, thereby directly affecting the product quality of the film material; based on the synergistic effect between the two kinds of nucleating agents and other composite processing aids, the heat aging resistance, tear resistance and impact strength of the film can be effectively improved, at the same time, the applicant accidentally found that the size of the opening agent particle size is crucial to the film quality and the friction coefficient.

[0088] The above is only the preferred embodiment of the present application, not other forms of the present application, any skilled in the art may use the above disclosed technical content to change or modify equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification of the above embodiments within the technical solution content of the present application, according to the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A nucleating agent for increasing rigidity and transparency in polyethylene film, characterized in that, The nucleating agent comprises a main nucleating agent and an auxiliary nucleating agent, wherein the main nucleating agent has a structural formula as shown in formula (1): （1） R1, R2, R3 are selected from hydrogen, C2-C5 alkyl, C2-C5 alkoxy, hydroxyl, and at least one is selected from hydroxyl, and one group is selected from C2-C5 alkoxy; R4, R5, R6 are selected from hydrogen, C2-C5 alkyl, C2-C5 alkoxy, and at least one is selected from C2-C5 alkoxy; M is a metal selected from any one of Ca, Mg, Al, Zn; The auxiliary nucleating agent has a structural formula as shown in formula (2): （2） wherein R7, R8are selected from C 12 -C 18 linear alkyl, sodium ions and at least one sodium ion; The mass ratio between the main nucleating agent and the auxiliary nucleating agent is 2-8:8-2.

2. A composite processing aid for polyethylene film stock, characterized by, The nucleating agent comprises an antioxidant, a light stabilizer, a lubricant, an antistatic agent, an opening agent, and a nucleating agent, wherein the nucleating agent is the nucleating agent provided in claim 1, wherein the additive amount of the nucleating agent is 200-5000 ppm; the additive amount of the antioxidant is 1000-2000 ppm; the additive amount of the light stabilizer is 500-1000 ppm; the additive amount of the lubricant is 500-1000 ppm; the additive amount of the antistatic agent is 500-1000 ppm; the additive amount of the opening agent is 200-800 ppm, and the particle size D50 of the opening agent is 10 um 3. The polyethylene film stock compound processing aid of claim 2, wherein, The antioxidant comprises at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 622, and antioxidant 626.

4. The polyethylene film stock compound processing aid of claim 2, wherein, The light stabilizer is at least one of ultraviolet absorber UV-328, light stabilizer 944, and light stabilizer 770.

5. The polyethylene film stock compound processing aid of claim 2, wherein, The lubricant is at least one of stearic acid, stearic acid monoglyceride, oleic acid, oleic acid monoglyceride, calcium stearate, and zinc stearate.

6. The polyethylene film stock compound processing aid of claim 2, wherein, The antistatic agent is at least one of lauryl trimethyl ammonium chloride, N-(3-alkoxy-2-hydroxypropyl) monoethanolamine, and hydroxyethyl alkylamine.

7. The polyethylene film stock compound processing aid of claim 2, wherein, The opening agent comprises at least one of silicon dioxide and hydrotalcite.

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