A composite additive for high-transparency high-opening polyethylene film and a preparation method thereof

Abstract

The application relates to the field of polyethylene film additives, in particular to a composite additive for high-transparency high-opening polyethylene film and a preparation method thereof.A composite additive for high-transparency high-opening polyethylene film, a raw material scheme comprising a composite antioxidant, an antistatic agent, a slip agent, an opening agent, an auxiliary resin and a combined synergist and the like.The composite additive provided by the application pre-disperses multiple functional components in one body in the form of particles, fundamentally solves the problems of dust flying, complicated batching and proportion segregation caused by respectively adding traditional multiple-component powders, and realizes convenient, clean and accurate integrated feeding.The additive particle morphology is regular and the components are uniform, the additive is easy to quickly melt and uniformly disperse in polyethylene resin during processing, and the stability of production and the consistency of film quality are significantly improved.

Description

Technical Field

[0001] This application relates to the field of polyethylene film additives, and in particular to a composite additive for high-transparency, high-opening polyethylene film and its preparation method. Background Technology

[0002] Polyethylene film, with its excellent processability, flexibility, and low cost, occupies an important position in many fields such as food packaging, agricultural mulching, and industrial packaging. With the continuous upgrading of downstream applications, the market is placing higher, often mutually restrictive, demands on film performance. High transparency and high opening capacity are two key technical indicators: high transparency requires the film to have low haze and high light transmittance, clearly displaying the packaged contents and enhancing product quality; high opening capacity requires the film surface to be resistant to sticking, ensuring smooth transport in high-speed processes such as automated bag making, printing, and heat sealing, avoiding equipment downtime or increased scrap rates due to film adhesion. However, these two properties are often contradictory in their implementation, making the simultaneous achievement of high transparency and high opening capacity a prominent challenge in polyethylene film formulation design.

[0003] To improve the opening performance of films, existing technologies commonly employ the method of adding inorganic opening agents to the resin matrix. This increases surface roughness by forming micron-sized protrusions on the film surface, thereby reducing the interlayer contact area and achieving an anti-adhesion effect. Simultaneously, to reduce the surface friction coefficient and improve the smooth feel, organic slip agents that can form an extremely thin lubricating layer on the film surface are usually introduced. Furthermore, to address the risks of thermo-oxidative degradation during processing and long-term use, the problem of static electricity accumulation, and the lubrication requirements of melt processing, the formulation often requires the compounding of thermo-oxidative stabilizers, antistatic agents, and metal soap-based processing aids. These functional additives are diverse in type and have distinct physical properties, collectively constituting the necessary components for achieving the multifunctionality of polyethylene films.

[0004] However, in actual production, when film manufacturers add the aforementioned inorganic powder opening agents and various organic functional additives separately, they face a series of prominent technical problems. First, the various additives differ significantly in particle size, density, and morphology. Simple mechanical mixing easily leads to component segregation and stratification, causing continuous fluctuations in the formulation ratio entering the extruder, ultimately resulting in poor batch stability of film opening properties and transparency. Second, the direct addition of large amounts of inorganic powder generates severe dust pollution, harming the working environment. Furthermore, inorganic particles are difficult to disperse uniformly in low-polarity polyethylene melt. Once micron-sized agglomerates form, they not only fail to effectively improve opening properties but also act as light scattering centers, significantly increasing film haze and severely impairing its transparency.

[0005] In summary, providing an integrated composite additive that can simultaneously achieve high transparency, high opening, convenient formulation, uniform dispersion, and stable processing has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned issues, the applicant has provided the following technical solutions: A composite additive for high-transparency, high-opening polyethylene film, comprising, by weight, the following raw materials: 18-26 parts of composite antioxidant, 6-12 parts of antistatic agent, 8-14 parts of lubricant, 20-30 parts of slip agent, 25-36 parts of opening agent, 12-20 parts of auxiliary resin, and 5-10 parts of combined synergist.

[0007] In a preferred embodiment, the composite antioxidant is at least one of antioxidant 1076, antioxidant 1010, antioxidant 3114, antioxidant 1790, antioxidant BHT, antioxidant 168, and antioxidant TNPP.

[0008] In a preferred embodiment, the composite antioxidant is a combination of antioxidant 1076 and antioxidant 168.

[0009] In a preferred embodiment, the mass ratio of antioxidant 1076 to antioxidant 168 is (7~9):(15~20).

[0010] In a preferred embodiment, the mass ratio of antioxidant 1076 to antioxidant 168 is (7~8):(16~18).

[0011] In a preferred embodiment, the mass ratio of the opening agent, auxiliary resin, and combined synergist is (2.8~3.2):(1.4~1.8):(0.6~0.9).

[0012] In a preferred embodiment, the mass ratio of the opening agent, auxiliary resin, and combined synergist is (2.8~3):(1.4~1.6):(0.6~0.8).

[0013] In a preferred embodiment, the antistatic agent is at least one selected from antistatic agent 1800, ethoxylated alkylamine, antistatic agent 190, and alkyl sulfonate antistatic agents.

[0014] In a preferred embodiment, the antistatic agent is antistatic agent 1800 or ethoxylated alkylamine.

[0015] In a preferred embodiment, the antistatic agent is antistatic agent 1800.

[0016] In a preferred embodiment, the lubricant is at least one of zinc stearate, calcium stearate, magnesium stearate, and 12-hydroxystearate.

[0017] In a preferred embodiment, the lubricant is zinc stearate, magnesium stearate, or zinc 12-hydroxystearate.

[0018] In a preferred embodiment, the lubricant is zinc stearate or magnesium stearate.

[0019] In a preferred embodiment, the lubricant is zinc stearate.

[0020] In a preferred embodiment, the slip agent is at least one of erucamide, oleamide, stearamide, and palmitamide.

[0021] In a preferred embodiment, the slip agent is erucamide or oleamide.

[0022] In a preferred embodiment, the slip agent is erucamide.

[0023] In a preferred embodiment, the opening agent is at least one of silica, diatomaceous earth, and zeolite powder.

[0024] In a preferred embodiment, the opening agent is silicon dioxide.

[0025] In a preferred embodiment, the average particle size of the silica is 1~2μm.

[0026] In a preferred embodiment, the average particle size of the silica is 1~1.4μm.

[0027] In a preferred embodiment, the auxiliary resin is LDPE and hydrogenated terpene resin.

[0028] In a preferred embodiment, the mass ratio of LDPE to hydrogenated terpene resin is (10~18):(3~5).

[0029] In a preferred embodiment, the mass ratio of LDPE to hydrogenated terpene resin is (12~16):(3~4).

[0030] In a preferred embodiment, the hydrogenated terpene resin is specifically Cleanon P105, manufactured by Yasuhara, Japan.

[0031] The composite additive of this application incorporates hydrogenated terpene resin as an interfacial compatibilizer and dispersant resin, which harmonizes the refractive index difference between the inorganic opening agent and the organic components. During melt processing, the hydrogenated terpene resin preferentially wets and coats the surface of silica particles, forming an interfacial buffer layer with a gradient refractive index, effectively weakening the scattering intensity of light passing through the two-phase interface, thereby significantly reducing film haze. At the same time, its excellent compatibility with the polyethylene matrix promotes the uniform dispersion of inorganic particles in the melt and inhibits the generation of agglomeration defects. This allows the composite additive to maintain high transparency while imparting good opening properties to the film, providing a foundation for improved overall performance.

[0032] In a preferred embodiment, the combined synergist is a combination of ethylene bis-stearamide, glyceryl monostearate, and behenamide.

[0033] In a preferred embodiment, the mass ratio of ethylene bis-stearamide, glyceryl monostearate, and behenamide is (2~5):(1~3):(1~2).

[0034] In a preferred embodiment, the mass ratio of ethylene bis-stearamide, glyceryl monostearate, and behenamide is (3~4):(1~2):(1~1.5).

[0035] The combined synergist incorporated in this application leverages the differences in melting points and complementary molecular structures of the components to achieve phased control over slip and opening properties. In the initial processing stage, the high-melting-point component provides internal lubrication in particulate form, promoting uniform dispersion of all components. In the subsequent placement stage, the amphiphilic bridging component enhances the compatibility between slip agents of different polarities and molecular weights, regulating overall migration behavior. The long-chain slow-release component, with its slow migration rate and low precipitation tendency, continuously replenishes the film's lubrication layer after the main slip agent is consumed. The combined effect of these three components imparts a durable and stable low coefficient of friction and opening properties to the film, providing stable overall performance.

[0036] A method for preparing a composite additive for high-transparency, high-opening polyethylene film includes the following steps: S1: The formulated amount of composite antioxidant and lubricant are added to a high-speed mixer and mixed to obtain a premix; the formulated amount of opening agent is added to the high-speed mixer, and preheated hydrogenated terpene resin is slowly added under stirring and mixed, and then cooled to obtain a pretreated powder; S2: In a low-speed kneader, antistatic agent, slip agent and combined synergist are added and heated and kneaded to obtain a solution; S3: The formulated amount of LDPE is added to the main feed port of a twin-screw extruder. After the resin melts, the pretreated powder, premix and solution are added sequentially through the side feed port. After thorough shearing, dispersion and homogenization, the mixture is extruded through the die head and granulated and cooled. The granules are centrifuged, dehydrated and dried in a fluidized bed, and then classified by a vibrating screen to remove excessively fine powder and excessively large particles to obtain the finished product.

[0037] The preferred embodiment of the method for preparing the composite additive for high-transparency, high-opening polyethylene film specifically includes the following steps: S1: Add the formulated amount of composite antioxidant and lubricant to a high-speed mixer at a speed of 300-500 rpm for 5-8 minutes to obtain a premix; add the formulated amount of opening agent to the high-speed mixer, and slowly add hydrogenated terpene resin preheated to 120-130°C under stirring, mixing at a speed of 600-800 rpm for 15-20 minutes, and obtain a pretreated powder after cooling; S2: Add the antistatic agent, slip agent, and combined synergist to a low-speed kneader, heat to 100-110°C, and mix at a speed of 160 rpm. Knead at ~180 rpm for 15~20 min to obtain the melt; S3: Add the formulated amount of LDPE to the main feed port of the twin-screw extruder. Set the temperature of each section of the extruder as follows: feeding section 100~120℃, compression section 120~140℃, homogenization section 140~150℃, and die head 145~150℃. After the resin melts, add the pretreated powder, premix and melt sequentially through the side feed port. After thorough shearing, dispersion and homogenization, extrude and granulate through the die head die hole and cool. The granules are centrifuged for dehydration and fluidized bed drying at 50~60℃ for 20~30 min. Classify by vibrating screen to remove excessively fine powder and excessively large particles to obtain the finished product.

[0038] Beneficial effects of the application plan: 1. The composite additive provided in this application pre-disperses multiple functional components into a single unit, supplied in granular form. This fundamentally solves the problems of dust generation, cumbersome mixing, and proportion segregation associated with the separate addition of traditional multi-component powders, achieving convenient, clean, and precise integrated feeding. The additive has a regular particle shape and uniform composition, easily and quickly melting and uniformly dispersing in polyethylene resin during processing, significantly improving production stability and film quality consistency. Crucially, through formulation optimization, this additive successfully overcomes the industry contradiction of balancing high opening requirements with high transparency. While imparting excellent opening smoothness to the film, it maximizes the film's high transparency, meeting the stringent requirements of high-end packaging for both visual display effects and automated operational efficiency.

[0039] 2. In the auxiliary resin added to the composite additive of this application, hydrogenated terpene resin serves as an interfacial compatibilizer and dispersant resin, harmonizing the refractive index difference between the inorganic opening agent and the organic components. During melt processing, the hydrogenated terpene resin preferentially wets and coats the surface of silica particles, forming an interfacial buffer layer with a gradient transition in refractive index. This effectively weakens the scattering intensity of light passing through the two-phase interface, thereby significantly reducing film haze. Simultaneously, its excellent compatibility with the polyethylene matrix promotes the uniform dispersion of inorganic particles in the melt and inhibits the generation of agglomeration defects. This allows the composite additive to maintain high transparency while imparting good opening properties to the film, providing a foundation for improved overall performance.

[0040] 3. The combined synergist added to the composite additive in this application utilizes the differences in melting points and complementary molecular structures of each component to achieve phased control of slip and opening performance. In the subsequent placement stage, the bridging component with amphiphilic structure enhances the compatibility between slip agents of different polarities and molecular weights, and controls the overall migration behavior. The three components work together to give the film a durable and stable low coefficient of friction and opening performance, and provide stable comprehensive performance. Detailed Implementation

[0041] Example 1 A composite additive for high-transparency, high-opening polyethylene film, comprising, by weight, the following raw materials: 24.5 parts composite antioxidant, 9.3 parts antistatic agent, 10.5 parts lubricant, 23.5 parts slip agent, 30 parts opening agent, 14.8 parts auxiliary resin, and 7.8 parts combined synergist.

[0042] The composite antioxidant is a combination of antioxidant 1076 and antioxidant 168 in a mass ratio of 7.5:17.5.

[0043] The antistatic agent is antistatic agent 1800; the lubricant is zinc stearate; the slip agent is erucamide; and the opening agent is silica with an average particle size of 1.2 μm.

[0044] The auxiliary resins are LDPE and hydrogenated terpene resin in a mass ratio of 15:3.5.

[0045] The hydrogenated terpene resin is Clearon P105, manufactured by Yasuhara Chemical Co., Ltd. in Japan; the LDPE is 2426H, manufactured by Sinopec Maoming Petrochemical Co., Ltd.

[0046] The combined synergist is a combination of ethylene bis-stearamide, glyceryl monostearate, and behenamide in a mass ratio of 3.6:1.4:1.2.

[0047] A method for preparing a composite additive for high-transparency, high-opening polyethylene film includes the following steps: S1: Add the formulated amount of composite antioxidant and lubricant to a high-speed mixer, mix at 400 rpm for 6 minutes to obtain a premix; add the formulated amount of opening agent to the high-speed mixer, and slowly add hydrogenated terpene resin preheated to 125°C under stirring, mix at 800 rpm for 20 minutes, and obtain a pretreated powder after cooling; S2: Add antistatic agent, slip agent and combined synergist to a low-speed kneader, heat to 105°C, knead at 180 rpm for 20 minutes to obtain a melt; S3: Add the formulated amount of LDPE to the main feed port of the twin-screw extruder. Set the temperatures of each section of the extruder as follows: feeding section 110℃, compression section 130℃, homogenization section 145℃, and die head 150℃. After the resin melts, add the pre-treated powder, premix, and melt sequentially through the side feed port. After thorough shearing, dispersion, mixing, and homogenization, extrude the mixture through the die head die, granulate, and cool it. The granules are then centrifuged, dehydrated, and dried in a fluidized bed at 60℃ for 25 minutes. The mixture is then graded using a vibrating screen to remove excessively fine powder and excessively large particles, thus obtaining the finished product.

[0048] Example 2 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that, by weight, its raw material scheme includes: 24.5 parts of composite antioxidant, 9.3 parts of antistatic agent, 10.5 parts of lubricant, 23.5 parts of slip agent, 28 parts of opening agent, 17.2 parts of auxiliary resin, and 6.5 parts of combined synergist.

[0049] Example 3 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that, by weight, its raw material scheme includes: 24.5 parts of composite antioxidant, 9.3 parts of antistatic agent, 10.5 parts of lubricant, 23.5 parts of slip agent, 30 parts of opening agent, 15 parts of auxiliary resin, and 8.5 parts of combined synergist.

[0050] Comparative Example 1 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that, by weight, its raw material scheme includes: 24.5 parts of composite antioxidant, 9.3 parts of antistatic agent, 10.5 parts of lubricant, 23.5 parts of slip agent, 35 parts of opening agent, 16.5 parts of auxiliary resin, and 2.5 parts of combined synergist.

[0051] Comparative Example 2 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that the auxiliary resin is LDPE and hydrogenated terpene resin in a mass ratio of 18:0.5.

[0052] Comparative Example 3 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that the auxiliary resin is LDPE and hydrogenated terpene resin in a mass ratio of 11:7.5.

[0053] Comparative Example 4 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that the combined synergist is a combination of ethylene bis-stearamide, glyceryl monostearate, and behenamide in a mass ratio of 4.5:0.2:1.5.

[0054] Comparative Example 5 A composite additive for high-transparency, high-opening polyethylene film differs from the examples in that the combined synergist is a combination of ethylene bis-stearamide, glyceryl monostearate, and behenamide in a mass ratio of 2:3.2:1.

[0055] Performance Evaluation 1. Haze: The composite additive was added at 3wt% of the total mass of LDPE 2426H resin, and a film with a thickness of 50μm was blow-molded. A 50mm×50mm sample was cut, and the haze value was measured at room temperature using a haze meter. The average value of the test at 5 different locations was taken, and the results were recorded in Table 1.

[0056] 2. Yellowing resistance: The composite additive was added at 3wt% of the total mass of LDPE 2426H resin and blow-molded into a film with a thickness of 50μm. The film was aged at 100℃ for 72h. After being removed and cooled to room temperature, the change in yellow index ΔYI of the film before and after aging was measured using a colorimeter. The average of 10 tests was recorded in Table 1.

[0057] 3. Opening property: The composite additive was added at 3wt% of the total mass of LDPE 2426H resin and blow-molded into a film with a thickness of 50μm. Two film samples with a size of 100mm×50mm were stacked together and placed at 0.5MPa pressure and 50℃ temperature for 24h. The force required to peel them off was measured at 100mm / min using a universal testing machine at room temperature. The results were recorded as the average of 10 tests in Table 1.

[0058] 4. Slip properties: The composite additive was added at 3wt% of the total mass of LDPE 2426H resin, and a film with a thickness of 50μm was blow-molded. After the film was placed at 23℃ and 50% relative humidity for 1 day and 30 days respectively, the sample was cut and the dynamic friction coefficient of the film was measured using a friction coefficient tester. The test speed was 100mm / min and the load was 200g. The change value of dynamic friction coefficient was recorded and the results were recorded in Table 1.

[0059] 5. Tensile strength test: The composite additive was added at 3wt% of the total mass of LDPE 2426H resin, and a 50μm thick film was blow-molded. Dumbbell-shaped specimens were cut and conditioned for 24 hours at 23℃ and 50% relative humidity. Tensile test was then performed using a universal testing machine at a speed of 200mm / min. The tensile strength was recorded, and the average value of 10 tests was recorded in Table 1.

[0060] Table 1 Performance Evaluation Table ; Test Result Analysis: The performance evaluation table shows that Examples 1-3 achieved superior performance results compared to Comparative Examples 1-5. This is attributed to the technical solutions specified in this application used in Examples 1-3. During melt processing, the hydrogenated terpene resin preferentially wets and coats the surface of silica particles, forming an interface buffer layer with a gradient refractive index. This effectively weakens the scattering intensity of light passing through the two-phase interface, significantly reducing film haze. While providing good opening properties, it maintains high transparency, laying the foundation for improved overall performance. Furthermore, the added synergist utilizes the differences in melting points and complementary molecular structures of the components to achieve phased control of slip and opening properties, resulting in a significant improvement in overall performance. Comparative Examples 1-5, on the other hand, employed different technical solutions than those specified in this application, leading to a significant decrease in the technical effect of their raw materials in the system, and consequently, a decline in the performance of the final product.

[0061] The above are merely preferred embodiments and comparative examples of the technical solutions of this application. It should be noted that for those skilled in the art, any improvements and substitutions made with the same ideas without departing from the principles described in this application should also be considered within the scope of protection of this application.

Claims

1. A composite additive for high transparent high opening polyethylene film, characterized in that: By weight, the raw material formula includes: 18-26 parts of composite antioxidant, 6-12 parts of antistatic agent, 8-14 parts of lubricant, 20-30 parts of slip agent, 25-36 parts of opening agent, 12-20 parts of auxiliary resin, and 5-10 parts of combined synergist. ​ The composite antioxidant is at least one of antioxidant 1076, antioxidant 1010, antioxidant 3114, antioxidant 1790, antioxidant BHT, antioxidant 168 and antioxidant TNPP; The auxiliary resin is LDPE and hydrogenated terpene resin in a mass ratio of (10~18):(3~5). The combined synergist is a combination of ethylene bis-stearamide, glyceryl monostearate and behenamide, in a mass ratio of (2~5):(1~3):(1~2).

2. The composite additive for high-transparency, high-opening polyethylene film according to claim 1, characterized in that: the antistatic agent is at least one selected from antistatic agent 1800, ethoxylated alkylamine, antistatic agent 190, and alkyl sulfonate antistatic agents.

3. The composite additive for high transparent high opening polyethylene film according to claim 2, characterized in that: The composite antioxidant is a combination of antioxidant 1076 and antioxidant 168, with a mass ratio of (7~9):(15~20).

4. The composite additive for high-transparency, high-opening polyethylene film according to claim 3, characterized in that: the lubricant is at least one of zinc stearate, calcium stearate, magnesium stearate and 12-hydroxystearate.

5. The composite additive for high-transparency, high-opening polyethylene film according to claim 4, characterized in that: The slip agent is at least one of erucamide, oleamide, stearamide, and palmitamide.

6. The composite additive for high-transparency, high-opening polyethylene film according to claim 5, characterized in that: The opening agent is at least one of silica, diatomaceous earth, and zeolite powder.

7. The composite additive for high-transparency, high-opening polyethylene film according to claim 6, characterized in that: The opening agent is silicon dioxide with an average particle size of 1~2μm.

8. The composite additive for high transparency and high opening polyethylene film according to claim 7, characterized in that the mass ratio of LDPE and hydrogenated terpene resin is (12~16):(3~4).

9. The composite additive for high-transparency, high-opening polyethylene film according to claim 8, characterized in that the mass ratio of ethylene bis-stearamide, glyceryl monostearate and behenamide is (3~4):(1~2):(1~1.5).

10. A method for preparing a composite additive for high-transparency, high-opening polyethylene film according to any one of claims 1 to 9, characterized in that: specific Includes the following steps: S1: Add the formulated amount of composite antioxidant and lubricant into a high-speed mixer and mix to obtain a premix; add the formulated amount of opening agent into a high-speed mixer, and slowly add the preheated hydrogenated terpene resin under stirring and mix. After cooling, obtain a pretreated powder. S2: In a low-speed kneader, add the antistatic agent, slip agent, and combined synergist, and heat and knead to obtain a melt; S3: Add the formulated amount of LDPE to the main feed port of a twin-screw extruder. After the resin melts, add the pretreated powder, premix, and melt sequentially through the side feed port. After thorough shearing, dispersion, and homogenization, extrude and granulate through the die head, cool, and then dehydrate and dry the granules by centrifugation and fluidized bed drying. Classify the granules by vibrating screen to remove excessively fine powder and excessively large particles to obtain the finished product.