Cellulose anti-blocking agent for processing polyolefin film as well as preparation method and application of cellulose anti-blocking agent

Abstract

The invention relates to a cellulose anti-blocking agent for processing a polyolefin film as well as a preparation method and application of the cellulose anti-blocking agent. The preparation method comprises the following steps: (1) mixing cellulose acetate-butyrate powder with a surface treating agent, carrying out surface treatment reaction, and drying to obtain modified cellulose micro powder; (2) mixing and stirring the modified cellulose micro powder and an anti-adhesion agent, and screening to remove the anti-adhesion agent to obtain a cellulose anti-blocking agent; the surface treating agent in the step (1) comprises acid liquor or alkali liquor; the anti-adhesion agent in the step (2) comprises any one or a combination of at least two of polyolefin, polydimethylsiloxane, polymethyl methacrylate or silicon dioxide. The prepared cellulose anti-blocking agent can solve the adhesion problem in the polyolefin film processing process, has the characteristics of high dispersion, high transparency, easy processing and low haze, has extremely high nucleation efficiency, and provides an excellent raw material for processing of the polyolefin film.

Description

Technical Field

[0001] This invention belongs to the field of plastic film technology, specifically relating to a cellulose opening agent for processing polyolefin films, its preparation method, and its application. Background Technology

[0002] During the processing of polyolefin films, due to molecular entanglement, van der Waals forces after film lamination, vacuum sealing effect, and electrostatic adsorption, the film layers adhere tightly and are difficult to separate. Therefore, when processing polyolefin film products, a certain amount of opening agent is usually added to open the adhered films.

[0003] Opening agents are generally mineral fillers of a certain particle size, such as talc, silica, kaolin, and calcium carbonate powder. These particles form tiny protrusions on the film surface, disrupting the vacuum between the films and causing them to separate. However, these mineral fillers themselves have problems such as low light transmittance, high oil absorption, and easy aggregation, which will reduce the film transparency to a certain extent and greatly increase the film haze.

[0004] Commonly available transparent nucleating agents for polyolefins include dibenzyl sorbitol derivatives. These nucleating agents are rich in hydroxyl and benzene ring structures, resulting in high nucleation efficiency. After cooling, they can self-assemble into three-dimensional nanostructures (fiber diameter ≤ 10 nm) through hydrogen bonding, ensuring that the nucleating agent forms a very fine dispersion. When the average spherulites formed by the induction are smaller than the wavelength of visible light, it can be considered that visible light can bypass the high-density, high-refractive-index crystal nuclei. At this point, highly transparent polyolefins can be obtained. However, transparent nucleating agents for polyolefins are expensive, and increasing the nucleating agent content will lead to increased haze.

[0005] Cellulose acetate-butyrate contains a large number of hydroxyl groups in its structure, and has high crystallinity and melting point (>220℃). Pretreatment can cause cellulose to swell, increasing the proportion of amorphous regions. During thermal processing, it provides nucleation sites for polyolefins and reduces the size of polyolefin crystal nuclei. At the same time, cellulose acetate-butyrate has extremely high modulus and extremely high transparency, which is basically at the level of glass.

[0006] However, there are no reports of using cellulose acetate butyrate instead of traditional opening agents such as silica to simultaneously provide nucleation sites for polyolefins during polyolefin blown film production. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a cellulose opening agent for processing polyolefin films, its preparation method, and its application.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a cellulose opening agent for processing polyolefin films, the method comprising the following steps:

[0010] (1) The cellulose acetate-butyrate powder was mixed with a surface treatment agent and subjected to a surface treatment reaction. After drying, the modified cellulose micro powder was obtained.

[0011] (2) Mix the modified cellulose micro powder with the anti-blocking agent, sieve to remove the anti-blocking agent, and obtain the cellulose opening agent;

[0012] The surface treatment agent in step (1) includes an acid or an alkaline solution;

[0013] The anti-blocking agent in step (2) includes any one or a combination of at least two of polyolefin, polydimethylsiloxane, polymethyl methacrylate or silica.

[0014] This invention chemically treats cellulose acetate-butyrate powder to swell and disrupt the amorphous and crystalline regions of the cellulose acetate-butyrate, increasing the number of hydroxyl groups at the chain ends. Through hydrogen bonding, the hydroxyl groups self-assemble into a three-dimensional nanofiber network, providing sites for polyolefin nucleation. Meanwhile, the high modulus and transparency of cellulose acetate-butyrate ensure its openability, thus preparing a cellulose opener with transparent and clarifying effects.

[0015] In addition, the modified cellulose micro powder still exhibits some adhesion after surface treatment. By treating the modified cellulose micro powder with an anti-adhesion agent to separate the adhered modified cellulose micro powder, and then sieving to remove the anti-adhesion agent, the resulting cellulose opening agent has superior opening performance and excellent clarification effect.

[0016] This invention provides a highly dispersed, highly transparent, easy-to-process, and low-haze cellulose opening agent for processing polyolefin films. This opening agent can solve the adhesion problem of polyolefin films during processing without affecting the transparency of the polyolefin films. At the same time, it has extremely high nucleation efficiency, which can improve the surface gloss of polyolefin films and reduce the haze of the finished films.

[0017] Preferably, the particle size (D50) of the cellulose acetate-butyrate powder in step (1) is 5-10 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0018] This invention controls the particle size of cellulose acetate-butyrate powder to 5-10 μm, which allows the prepared cellulose opening agent to form tiny "protrusions" on the film surface, reducing the contact area between films, lowering adhesion, and controlling the coefficient of friction and processing performance of the film within a reasonable range.

[0019] Preferably, the cellulose acetate-butyrate powder is obtained by pulverizing cellulose acetate-butyrate particles.

[0020] Preferably, the butyryl content in the cellulose acetate-butyrate particles is 25-30%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0021] Preferably, the acetyl content in the cellulose acetate-butyrate particles is 10-20%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, etc.

[0022] By controlling the content of butyryl and acetyl groups in cellulose acetate-butyrate particles within the above-mentioned range, this invention can regulate the intermolecular forces of cellulose, thereby making the prepared cellulose opening agent more effective in reducing adhesion.

[0023] Preferably, the melting temperature of the cellulose acetate-butyrate particles is above 220°C (e.g., 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, etc.), and the glass transition temperature is above 150°C (e.g., 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc.).

[0024] Preferably, the crushing pressure is 0.65-0.85 MPa (e.g., 0.65 MPa, 0.7 MPa, 0.75 MPa, 0.8 MPa, 0.85 MPa, etc.), and the crushing speed is 6000-8000 rpm (e.g., 6000 rpm, 6500 rpm, 7000 rpm, 7500 rpm, 8000 rpm, etc.).

[0025] Preferably, the cellulose acetate-butyrate powder in step (1) is mixed with the surface treatment agent, and the surface treatment reaction is carried out in either of the following two ways:

[0026] (i) The cellulose acetate-butyrate powder is first mixed with a weak acid aqueous solution with a mass percentage of 5-10%, and then mixed with a strong acid aqueous solution with a mass percentage of 0.5-1.5% to carry out a surface treatment reaction;

[0027] (ii) The cellulose acetate-butyrate powder is mixed with an alkaline solution of 5-25% by mass and subjected to a surface treatment reaction.

[0028] Among them, the specific point values ​​for 5-10% can be 5%, 6%, 7%, 8%, 9%, 10%, etc.; the specific point values ​​for 0.5-1.5% can be 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, etc.; and the specific point values ​​for 5-25% can be 5%, 10%, 15%, 20%, 25%, etc.

[0029] This invention involves surface treatment of cellulose acetate-butyrate powder with acid or alkali solutions, which can better disrupt the amorphous and crystalline regions of cellulose and increase the number of hydroxyl groups at the chain ends.

[0030] Furthermore, when using acid as a surface treatment agent, mixing cellulose acetate-butyrate powder with a weak acid first, and then mixing it with a low-concentration strong acid, can further enhance the modification effect of the acid on the cellulose structure, ultimately reducing the haze and increasing the tensile strength of the polyolefin film when preparing it from the cellulose opening agent.

[0031] Furthermore, by controlling the mass percentage of acid in the weak acid aqueous solution to 5-10%, the cellulose structure can be further improved, and the resulting opening agent has a better effect in reducing film haze.

[0032] Preferably, the surface treatment reaction temperature in method (i) is 30-50°C (e.g., 30°C, 35°C, 40°C, 45°C, 50°C, etc.), and the surface treatment reaction time is 10-30 min (e.g., 10 min, 15 min, 20 min, 25 min, 30 min, etc.).

[0033] Preferably, the weak acid aqueous solution in method (i) includes an aqueous solution of acetic acid and / or an aqueous solution of phosphoric acid.

[0034] Preferably, the strong acid aqueous solution in method (i) includes any one or a combination of at least two of sulfuric acid aqueous solution, hydrochloric acid or nitric acid aqueous solution.

[0035] Preferably, after the surface treatment reaction described in method (i), the reaction solution is further mixed with a reaction termination solution to terminate the reaction.

[0036] Preferably, the reaction termination solution comprises an aqueous solution of sodium carbonate.

[0037] Preferably, the surface treatment reaction temperature in method (ii) is 15-35°C (e.g., 15°C, 20°C, 25°C, 30°C, 35°C, etc.), and the surface treatment reaction time is 0.5-2 h (e.g., 0.5 h, 1 h, 1.5 h, 2 h, etc.).

[0038] Preferably, the alkaline solution in method (ii) comprises an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide.

[0039] Preferably, after the surface treatment reaction in step (1), the pH value of the system is adjusted to 6-8, for example, it can be 6, 6.5, 7, 7.5, 8, etc.

[0040] Preferably, the anti-blocking agent in step (2) comprises a combination of polyolefin, polydimethylsiloxane and silicon dioxide.

[0041] This invention creatively discovers that using polyolefin, polydimethylsiloxane, and silica simultaneously as anti-blocking agents results in a significant synergistic effect in improving the haze reduction of cellulose opening agents.

[0042] Preferably, the particle size (D50) of the polyolefin is 100-150 μm, for example, it can be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc.

[0043] Preferably, the particle size (D50) of the polydimethylsiloxane is 2-4 μm, for example, it can be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc.

[0044] Preferably, the particle size (D50) of the silica is 12-16 μm, for example, it can be 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, etc.

[0045] Preferably, the mass ratio of the polyolefin, polydimethylsiloxane and silicon dioxide is 1:(0.1-0.5):(0.5-1).

[0046] Among them, the specific point values ​​in 0.1-0.5 can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc., and the specific point values ​​in 0.5-1 can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, etc.

[0047] Preferably, the mass ratio of the modified cellulose micropowder to the anti-blocking agent is 1:1 to 1:5, for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0048] Preferably, the mixing speed in step (2) is 2000-4000 rpm, for example, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, etc.

[0049] Preferably, the polyolefin film includes any one of polyethylene film, polypropylene film, or polybutene film.

[0050] In a second aspect, the present invention provides a cellulose opening agent for processing polyolefin films prepared by the method described in the first aspect.

[0051] Thirdly, the present invention provides a method for preparing a polyolefin film, the method comprising the following steps:

[0052] The polyolefin base powder, the cellulose opening agent and the slip agent for processing polyolefin film described in the second aspect are mixed, extruded and granulated, and blown into film to obtain a polyolefin film.

[0053] Preferably, the slip agent comprises erucamide.

[0054] Preferably, the mass ratio of the polyolefin base powder, the cellulose opening agent for processing polyolefin film, and the slip agent is 100:(0.1-0.5):(0.05-0.3).

[0055] The specific point values ​​in the range of 0.1-0.5 can be 0.1, 0.2, 0.3, 0.4, 0.5, etc., and the specific point values ​​in the range of 0.05-0.3 can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, etc.

[0056] Preferably, the polyolefin base powder comprises linear low-density polyethylene.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] This invention provides a highly dispersed, highly transparent, easy-to-process, and low-haze cellulose opening agent for polyolefin films. This opening agent can solve the adhesion problem in the polyolefin film processing process, without affecting the transparency of the polyolefin film, and at the same time has extremely high nucleation efficiency, which can improve the surface gloss of the polyolefin film and reduce the haze of the finished film. Detailed Implementation

[0059] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.

[0060] Example 1

[0061] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0062] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.75 MPa and the classifier speed to 7000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=6.5 μm. The butyryl content of the above cellulose acetate-butyrate particles is 28%, the acetyl content is 15%, the melting temperature is 225℃, and the glass transition temperature is 155℃.

[0063] (2) Add cellulose acetate-butyrate powder to 500 g of 7% phosphoric acid aqueous solution, slowly add 1% sulfuric acid aqueous solution, stir magnetically to prevent powder sticking, react at 35°C for 20 min, and then immediately add 75 mL of saturated sodium carbonate solution to terminate the reaction. After the reaction is complete, perform solid-liquid separation using a Buchner funnel, take a large amount of deionized water to repeatedly wash the solid phase until pH≈7, dehydrate using a centrifuge, and vacuum dry at 60°C to obtain modified cellulose micro powder.

[0064] (3) The modified cellulose powder and the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=120 μm), polydimethylsiloxane (particle size D50=3 μm) and silica (particle size D50=15 μm) in a mass ratio of 1:0.5:0.5) were mixed at a mass ratio of 1:3. After mixing, the mixture was stirred in a pulverizer (speed of 3000 rpm), and the anti-blocking agent was removed by re-sieving to obtain the cellulose opening agent.

[0065] Example 2

[0066] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0067] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.65 MPa and the classifier speed to 6000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=5 μm. The butyryl content of the above cellulose acetate-butyrate particles is 25%, the acetyl content is 20%, the melting temperature is 222℃, and the glass transition temperature is 152℃.

[0068] (2) Add cellulose acetate-butyrate powder to 500 g of 5% phosphoric acid aqueous solution, slowly add 1.5% sulfuric acid aqueous solution, stir magnetically to prevent powder sticking, react at 30°C for 30 min, and then immediately add 80 mL of saturated sodium carbonate solution to terminate the reaction. After the reaction is complete, perform solid-liquid separation using a Buchner funnel, take a large amount of deionized water to repeatedly wash the solid phase until pH≈7, dehydrate using a centrifuge, and vacuum dry at 60°C to obtain modified cellulose micro powder.

[0069] (3) The modified cellulose powder above is mixed with the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=110 μm), polydimethylsiloxane (particle size D50=2 μm) and silica (particle size D50=12 μm) in a mass ratio of 1:0.1:1) in a mass ratio of 1:1. After mixing, the mixture is stirred with a pulverizer (speed of 2000 rpm), and then re-sieved to remove the anti-blocking agent to obtain the cellulose opening agent.

[0070] Example 3

[0071] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0072] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.85 MPa and the classifier speed to 8000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=5 μm. The cellulose acetate-butyrate particles have a butyryl content of 30%, an acetyl content of 10%, a melting temperature of 228℃, and a glass transition temperature of 158℃.

[0073] (2) Add cellulose acetate-butyrate powder to 500 g of 10% phosphoric acid aqueous solution, slowly add 0.5% sulfuric acid aqueous solution, stir magnetically to prevent powder sticking, react at 50°C for 10 min, and then immediately add 60 mL of saturated sodium carbonate solution to terminate the reaction. After the reaction is complete, perform solid-liquid separation using a Buchner funnel, take a large amount of deionized water to repeatedly wash the solid phase until pH≈7, dehydrate using a centrifuge, and vacuum dry at 60°C to obtain modified cellulose micro powder.

[0074] (3) The modified cellulose micro powder and the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=140 μm), polydimethylsiloxane (particle size D50=4 μm) and silica (particle size D50=15 μm) in a mass ratio of 1:0.3:0.7) were mixed at a mass ratio of 1:5. After mixing, the mixture was stirred in a pulverizer (speed of 4000 rpm), and the anti-blocking agent was removed by re-sieving to obtain the cellulose opening agent.

[0075] Example 4

[0076] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0077] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.75 MPa and the classifier speed to 7000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=6.5 μm. The butyryl content of the above cellulose acetate-butyrate particles is 28%, the acetyl content is 15%, the melting temperature is 225℃, and the glass transition temperature is 155℃.

[0078] (2) Pour cellulose acetate-butyrate powder into 330 g of 10% NaOH aqueous solution, stir magnetically to prevent powder sticking, and react at 25°C for 1 h. After the reaction is complete, perform solid-liquid separation using a Buchner funnel, take a large amount of dilute acetic acid water to repeatedly wash the solid phase until pH≈7, dehydrate using a centrifuge, and vacuum dry at 60°C to obtain modified cellulose micro powder.

[0079] (3) The modified cellulose powder and the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=130 μm), polydimethylsiloxane (particle size D50=3 μm) and silica (particle size D50=16 μm) in a mass ratio of 1:0.5:0.5) were mixed at a mass ratio of 1:3. After mixing, the mixture was stirred in a pulverizer (speed of 3000 rpm), and the anti-blocking agent was removed by re-sieving to obtain the cellulose opening agent.

[0080] Example 5

[0081] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0082] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.65 MPa and the classifier speed to 6000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=5 μm. The butyryl content of the above cellulose acetate-butyrate particles is 25%, the acetyl content is 20%, the melting temperature is 222℃, and the glass transition temperature is 152℃.

[0083] (2) Pour cellulose acetate-butyrate powder into 330 g of 5% NaOH aqueous solution, stir magnetically to prevent powder sticking, and react at 15°C for 2 h. After the reaction is completed, solid-liquid separation is performed using a Buchner funnel, and the solid phase is repeatedly washed with a large amount of dilute acetic acid water until pH≈7. The solid phase is then dehydrated using a centrifuge and vacuum dried at 60°C to obtain modified cellulose micro powder.

[0084] (3) The modified cellulose powder above is mixed with the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=100 μm), polydimethylsiloxane (particle size D50=2 μm) and silica (particle size D50=12 μm) in a mass ratio of 1:0.1:1) in a mass ratio of 1:1. After mixing, the mixture is stirred with a pulverizer (speed of 2000 rpm), and then re-sieved to remove the anti-blocking agent to obtain the cellulose opening agent.

[0085] Example 6

[0086] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films, comprising the following steps:

[0087] (1) Take 50 g of cellulose acetate-butyrate particles and put them into an air jet mill. Set the working pressure to 0.85 MPa and the classifier speed to 8000 rpm. Grind them into cellulose acetate-butyrate powder with a particle size D50=5 μm. The cellulose acetate-butyrate particles have a butyryl content of 30%, an acetyl content of 10%, a melting temperature of 228℃, and a glass transition temperature of 158℃.

[0088] (2) The cellulose acetate-butyrate powder was poured into 330 g of 25% NaOH aqueous solution and magnetically stirred to prevent the powder from sticking together. The reaction was carried out at 35°C for 0.5 h. After the reaction was completed, solid-liquid separation was performed using a Buchner funnel. The solid phase was repeatedly washed with a large amount of dilute acetic acid water until the pH was ≈7. The solid phase was then dehydrated using a centrifuge and vacuum dried at 60°C to obtain modified cellulose micro powder.

[0089] (3) The modified cellulose powder and the anti-blocking agent (linear low-density polyethylene 7042 (particle size D50=140 μm), polydimethylsiloxane (particle size D50=4 μm) and silica (particle size D50=16 μm) in a mass ratio of 1:0.3:0.7) were mixed at a mass ratio of 1:5. After mixing, the mixture was stirred in a pulverizer (speed of 4000 rpm), and then re-sieved to remove the anti-blocking agent to obtain the cellulose opening agent.

[0090] Example 7

[0091] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 1 is that in step (2), after pouring cellulose acetate-butyrate powder into 500 g of phosphoric acid aqueous solution with a mass percentage of 7%, sulfuric acid aqueous solution is not added. All other steps are consistent with Example 1.

[0092] Example 8

[0093] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that step (2) is not mixed with an aqueous solution of phosphoric acid. Instead, cellulose acetate-butyrate powder is poured into an aqueous solution containing 7% phosphoric acid and 1% sulfuric acid (by mass percentage). All other steps are consistent with Example 1.

[0094] Example 9

[0095] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that in step (3), the anti-blocking agent is adjusted to a mass ratio of 1:0.5 of linear low-density polyethylene 7042 (particle size D50=120 μm) and polydimethylsiloxane (particle size D50=2 μm). The remaining steps are consistent with those in Example 1.

[0096] Example 10

[0097] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that in step (3), the anti-blocking agent is adjusted to linear low-density polyethylene 7042 (particle size D50=120μm) and silica (particle size D50=15μm) with a mass ratio of 1:0.5. All other steps are consistent with Example 1.

[0098] Example 11

[0099] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that in step (3), the anti-blocking agent is adjusted to a mass ratio of 0.5:0.5 of polydimethylsiloxane (particle size D50=3 μm) and silica (particle size D50=15 μm). The remaining steps are consistent with Example 1.

[0100] Example 12

[0101] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 1 is that in step (1), the butyryl group content in the cellulose acetate-butyrate particles is adjusted to 18%, and the acetyl group content is adjusted to 25%. All other steps are the same as in Example 1.

[0102] Example 13

[0103] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 1 is that in step (1), the butyryl content in the cellulose acetate-butyrate particles is adjusted to 36% and the acetyl content is adjusted to 7%. All other steps are consistent with Example 1.

[0104] Example 14

[0105] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that the mass percentage of phosphoric acid in the phosphoric acid aqueous solution is adjusted to 3% in step (2), while the other steps are consistent with Example 1.

[0106] Example 15

[0107] This embodiment provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this embodiment and Example 1 is that the mass percentage of phosphoric acid in the phosphoric acid aqueous solution is adjusted to 12% in step (2), while the other steps are consistent with Example 1.

[0108] Comparative Example 1

[0109] This comparative example provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 1 is that the surface treatment in step (2) is not performed. After obtaining cellulose acetate-butyrate powder in step (1), it is directly mixed, crushed, and sieved with the anti-blocking agent in step (3). The remaining steps are consistent with those in Example 1.

[0110] Comparative Example 2

[0111] This comparative example provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 1 is that step (3) is omitted. The modified cellulose micropowder obtained in step (2) is used as the cellulose opening agent. All other steps are consistent with those in Example 1.

[0112] Comparative Example 3

[0113] This comparative example provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 4 is that the surface treatment in step (2) is not performed. After obtaining cellulose acetate-butyrate powder in step (1), it is directly mixed, crushed, and sieved with the anti-blocking agent in step (3). The remaining steps are consistent with those in Example 4.

[0114] Comparative Example 4

[0115] This comparative example provides a method for preparing a cellulose opening agent for processing polyolefin films. The only difference between this method and Example 4 is that step (3) is omitted. The modified cellulose micropowder obtained in step (2) is used as the cellulose opening agent. All other steps are consistent with those in Example 4.

[0116] Application Example 1

[0117] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0118] By weight percentage, 51.7% linear low-density polyethylene 7042, 48% linear low-density polyethylene 8320, 0.2% cellulose opening agent prepared in Example 1, and 0.1% erucamide were mixed, extruded, granulated, and blown into a film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0119] Application Example 2

[0120] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0121] By weight percentage, 55% linear low-density polyethylene 7042, 44.5% linear low-density polyethylene 8320, 0.3% of the cellulose opening agent prepared in Example 2, and 0.2% erucamide were mixed, extruded and granulated, and blown into a film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0122] Application Example 3

[0123] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0124] By weight percentage, 35% linear low-density polyethylene 7042, 64.8% linear low-density polyethylene 8320, 0.1% cellulose opening agent prepared in Example 3, and 0.1% erucamide were mixed, extruded and granulated, and blown into film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0125] Application Example 4

[0126] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0127] By weight percentage, 51.7% linear low-density polyethylene 7042, 48% linear low-density polyethylene 8320, 0.2% of the cellulose opening agent prepared in Example 4, and 0.1% erucamide were mixed, extruded and granulated, and blown into a film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0128] Application Example 5

[0129] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0130] By weight percentage, 55% linear low-density polyethylene 7042, 44.5% linear low-density polyethylene 8320, 0.3% cellulose opening agent prepared in Example 5, and 0.2% erucamide were mixed, extruded and granulated, and blown into a film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0131] Application Example 6

[0132] This application example provides a method for preparing a polyethylene film, comprising the following steps:

[0133] By weight percentage, 35% linear low-density polyethylene 7042, 64.8% linear low-density polyethylene 8320, 0.1% cellulose opening agent prepared in Example 6, and 0.1% erucamide were mixed, extruded and granulated, and blown into film to obtain a polyethylene film with a thickness of 2.8-3 filaments.

[0134] Application Example 7-15

[0135] Application Examples 7-15 each provide a method for preparing a polyethylene film. The only difference between them and Application Example 1 is that the cellulose opening agent prepared in Example 1 is replaced with the cellulose opening agent prepared in Examples 7-15, respectively. All other steps are the same as in Application Example 1.

[0136] Compare and contrast examples 1-4

[0137] Comparative Examples 1-4 each provide a method for preparing a polyethylene film. The only difference between them and Application Example 1 is that the cellulose opening agent prepared in Example 1 is replaced with the cellulose opening agent prepared in Comparative Examples 1-4 in turn. All other steps are the same as in Application Example 1.

[0138] Comparative Application Example 5

[0139] This comparative application example provides a method for preparing a polyethylene film, which differs from Application Example 1 only in that the cellulose opening agent prepared in Example 1 is replaced with a commercially available silica opening agent AB905, while the remaining steps are consistent with Application Example 1.

[0140] Test Example 1

[0141] Performance testing of polyethylene film.

[0142] (1) Test objects: polyethylene films of each application example and comparative application example.

[0143] (2) Test indicators and test methods:

[0144] (2.1) The static friction coefficient, longitudinal tensile strength and longitudinal tensile elongation of the polyethylene film were tested using an MTS universal testing machine;

[0145] (2.2) The transmittance and haze of the polyethylene film were tested using a WGT-S transmittance / haze meter;

[0146] (2.3) Based on the actual application scenario, assess the adhesion resistance between films through manual peeling:

[0147] ① Easy to tear: No resistance, instant separation, no signs of sticking;

[0148] ② Relatively easy to tear: slight resistance, no force required, slight signs of adhesion;

[0149] ③ Difficult to tear: requires pulling force, and there are obvious signs of adhesion at the edges.

[0150] (3) Test results:

[0151] The parameters of each polyethylene film are shown in Table 1.

[0152] Table 1

[0153]

[0154] As can be seen from the data in Table 1, the cellulose opening agent prepared by the present invention can significantly solve the problem of film adhesion; and compared with the commercially available AB905 opening agent, it can significantly reduce film haze and improve film tensile strength without affecting light transmittance.

[0155] The data from Application Example 1 and Comparative Application Example 1 / Application Example 4 and Comparative Application Example 3 show that, during the preparation of the opening agent, surface treatment by adding acid or alkali can improve the light transmittance and low haze effect of the opening agent.

[0156] The data from Application Example 1 and Comparative Application Example 2 / Application Example 4 and Comparative Application Example 4 show that by using an anti-blocking agent to treat the modified cellulose micropowder, the adhered modified cellulose micropowder is separated, avoiding the aggravation of light scattering caused by the adhesion of micropowder. The resulting cellulose opening agent has better opening performance and better clarification effect.

[0157] A comparison of the data from Application Example 1 and Application Examples 7-8 shows that when acid is used as a surface treatment agent, mixing cellulose acetate-butyrate powder with a weak acid first, and then mixing it with a low-concentration strong acid, can effectively control the degree of hydrolysis and further enhance the modification effect of the acid on the cellulose structure. Ultimately, this reduces the haze and increases the tensile strength of the polyolefin film when the cellulose opening agent is used to prepare the film.

[0158] A comparison of the data from Application Example 1 and Application Examples 9-11 shows that using polyolefin, polydimethylsiloxane, and silica as anti-blocking agents simultaneously has a significant synergistic effect in improving the haze reduction effect of cellulose opening agents.

[0159] A comparison of the data from Application Example 1 and Application Examples 12-13 shows that controlling the butyryl group content in the cellulose acetate-butyrate particles to 25-30% and the acetyl group content to 10-20% can better and more effectively regulate the intermolecular forces of cellulose, balance polarity and hydrophobicity, and make the prepared cellulose opening agent easier to disperse and reduce the risk of film adhesion.

[0160] A comparison of the data from Application Example 1 and Application Examples 14-15 shows that when acid is used as a surface treatment agent, controlling the mass percentage of acid in the weak acid aqueous solution to 5-10% can further improve the cellulose structure, increase the nucleation efficiency, and the resulting opening agent has a better effect in reducing film haze.

[0161] The applicant declares that the technical solution of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

[0162] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0163] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for preparing a cellulose opening agent for processing polyolefin films, characterized in that, The preparation method includes the following steps: (1) The cellulose acetate-butyrate powder was mixed with a surface treatment agent and subjected to a surface treatment reaction. After drying, the modified cellulose micro powder was obtained. (2) Mix the modified cellulose micro powder with the anti-blocking agent, sieve to remove the anti-blocking agent, and obtain the cellulose opening agent; The surface treatment agent in step (1) includes an acid or an alkaline solution; The anti-blocking agent in step (2) includes any one or a combination of at least two of polyolefin, polydimethylsiloxane, polymethyl methacrylate or silica.

2. The preparation method according to claim 1, characterized in that, The particle size of the cellulose acetate-butyrate powder in step (1) is 5-10 μm; Preferably, the cellulose acetate-butyrate powder is obtained by pulverizing cellulose acetate-butyrate particles; Preferably, the butyryl group content in the cellulose acetate-butyrate granules is 25-30%; Preferably, the acetyl content in the cellulose acetate-butyrate granules is 10-20%; Preferably, the melting temperature of the cellulose acetate-butyrate particles is above 220°C, and the glass transition temperature is above 150°C.

3. The preparation method according to claim 1 or 2, characterized in that, In step (1), the cellulose acetate-butyrate powder is mixed with a surface treatment agent, and the surface treatment reaction is carried out in either of the following two ways: (i) The cellulose acetate-butyrate powder is first mixed with a weak acid aqueous solution with a mass percentage of 5-10%, and then mixed with a strong acid aqueous solution with a mass percentage of 0.5-1.5% to carry out a surface treatment reaction; (ii) The cellulose acetate-butyrate powder is mixed with an alkaline solution of 5-25% by mass and subjected to a surface treatment reaction.

4. The preparation method according to claim 3, characterized in that, The surface treatment reaction temperature in method (i) is 30-50℃, and the surface treatment reaction time is 10-30 min; Preferably, the weak acid aqueous solution in method (i) comprises an aqueous solution of acetic acid and / or an aqueous solution of phosphoric acid; Preferably, the strong acid aqueous solution in method (i) includes any one or a combination of at least two of sulfuric acid aqueous solution, hydrochloric acid or nitric acid aqueous solution.

5. The preparation method according to claim 3, characterized in that, The surface treatment reaction temperature described in method (ii) is 15-35℃, and the surface treatment reaction time is 0.5-2 h; Preferably, the alkaline solution in method (ii) comprises an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide.

6. The preparation method according to any one of claims 1-5, characterized in that, After the surface treatment reaction described in step (1), the pH value of the system is adjusted to 6-8.

7. The preparation method according to any one of claims 1-6, characterized in that, The anti-blocking agent in step (2) comprises a combination of polyolefin, polydimethylsiloxane and silica; Preferably, the mass ratio of the polyolefin, polydimethylsiloxane, and silicon dioxide is 1:(0.1-0.5):(0.5-1); Preferably, the mass ratio of the modified cellulose micropowder to the anti-blocking agent is 1:1 to 1:

5.

8. The preparation method according to any one of claims 1-7, characterized in that, The polyolefin film includes any one of polyethylene film, polypropylene film, or polybutene film.

9. The cellulose opening agent for processing polyolefin films prepared by the method of any one of claims 1-8.

10. A method for preparing a polyolefin film, characterized in that, The preparation method includes the following steps: The polyolefin base powder, the cellulose opening agent for processing polyolefin film as described in claim 9, and the slip agent are mixed, extruded and granulated, and blown into film to obtain a polyolefin film. Preferably, the slip agent comprises erucamide.

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