BOPE matt film and preparation method thereof

Abstract

The application provides a BOPE matt film and a preparation method thereof, and relates to the technical field of matt film preparation. The method comprises the following steps: (1) preparing upper surface layer, first surface layer, core layer, second surface layer and matt layer raw materials, respectively; the mass ratio of the matt master batch and the homopolymer polyethylene in the matt layer raw material is 80-90:10-20; (2) co-extruding and casting the upper surface layer, the first surface layer, the core layer, the second surface layer and the matt layer raw materials to form a cast sheet; the cast sheet is kept at 200 DEG C for 10-60 min, and then kept at 120 DEG C for 10-60 min; the matt layer is in contact with air; (3) sequentially performing longitudinal stretching and transverse stretching to form a BOPE matt film; and the prepared BOPE matt film has good matt effect.

Description

Technical Field

[0001] This invention relates to the field of matte film preparation technology, specifically to a BOPE matte film and its preparation method. Background Technology

[0002] BOPE matte film is a packaging film with high haze, low gloss, and a diffuse reflective matte effect. Its surface is similar to paper, with a very low gloss and weak, soft light reflection. When laminated with BOPE, it can create the image of a natural product in food packaging. For book and magazine covers and promotional posters, lamination with BOPE provides excellent surface matte effect, good ink absorption, and good water vapor barrier properties, enabling realistic printing reproduction and a good three-dimensional effect. Laminating BOPE with packaging paper can significantly enhance the quality of packaging, giving it a paper-like effect and a luxurious feel. It is widely used in soap, tobacco, alcohol, clothing, footwear, perfume, cosmetics, and pharmaceuticals.

[0003] In the production of BOPE matte film, frequent film breakage is a significant issue. The main cause of breakage is die lip adhesion. A common method to address die lip adhesion is to lower the temperature of the extruder with added matte material. However, temperature is also a major factor affecting the matte effect. When the extruder temperature with added matte material is lowered to below 225℃, the crystallinity of the matte layer decreases, leading to a reduction in surface roughness and haze. This results in poor matte effect of the BOPE matte film, failing to meet customer requirements.

[0004] Therefore, providing a method for preparing a BOPE matting film that can maintain both a low film breakage rate and a good matting effect has become an urgent technical problem to be solved. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a BOPE matting film and its preparation method, solving the technical problem of poor matting effect of BOPE matting films prepared by existing methods.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing a BOPE matte film includes the following steps:

[0010] (1) Prepare raw materials for the upper surface layer, the first surface layer, the core layer, the second surface layer and the matte layer respectively. The matte layer raw materials include matte masterbatch and homopolymer polyethylene. The mass ratio of the matte masterbatch and homopolymer polyethylene is 80-90:10-20.

[0011] (2) The five layers of raw materials, namely the upper surface layer, the first surface layer, the core layer, the second surface layer and the matte layer, are co-extruded and cast to form a cast sheet. The cast sheet is kept at 200°C for 10 min-60 min and then kept at 120°C for 10 min-60 min.

[0012] The matte layer is in contact with air;

[0013] (3) After being subjected to longitudinal stretching and transverse stretching processes, a BOPE matte film is formed.

[0014] Preferably, the upper surface material includes homopolymer polyethylene and an anti-sticking agent, wherein the mass ratio of homopolymer polyethylene to anti-sticking agent is 93-95:5.0-7.0.

[0015] Preferably, the raw materials for the first and second surface layers include homopolymer polyethylene.

[0016] Preferably, the core layer raw material includes homopolymer polyethylene and anti-adhesive, wherein the mass ratio of homopolymer polyethylene to anti-adhesive is 98-99:1.0-2.0.

[0017] Preferably, the matte layer material further includes silica, and the mass ratio of the matte masterbatch, homopolymer polyethylene, and silica is 30-80:10-20:0.1-10.

[0018] Preferably, the longitudinal stretching process is as follows: preheating temperature is 100-115℃, stretching temperature is 80-95℃, stretching ratio is 3.8-4.0, and setting temperature is 110-125℃.

[0019] Preferably, the transverse stretching process is as follows: preheating temperature is 120-135℃, stretching temperature is 115-130℃, stretching ratio is 6-8, and setting temperature is 125-140℃.

[0020] On the other hand, a BOPE matte film prepared by a preparation method includes, from top to bottom, an upper surface layer, a first surface layer, a core layer, a second surface layer, and a matte layer.

[0021] Preferably, the thickness of the BOPE matte film is 15-25 μm, and the thickness of the matte layer is 0.5-2.5 μm.

[0022] Preferably, the thickness of the matte layer accounts for 2-15% of the total thickness of the BOPE matte film.

[0023] (III) Beneficial Effects

[0024] This invention provides a method for preparing a BOPE matte film. Compared with the prior art, it has the following advantages:

[0025] The method for preparing BOPE matte film in this application includes matte masterbatch and homopolymer polyethylene as raw materials, with a mass ratio of matte masterbatch to homopolymer polyethylene of 80-90:10-20. The mixture is formed by five-layer co-extrusion casting, and the cast sheet is kept at 200℃ for 10-60 minutes, and then kept at 120℃ for 10-60 minutes. The mixture is then subjected to longitudinal stretching and transverse stretching treatments to form BOPE matte film. In the matting layer, the matting masterbatch is the continuous phase and the homopolymer polyethylene is the dispersed phase. After holding at 200℃ for 10-60 minutes, the matting masterbatch begins to crystallize. The homopolymer polyethylene is dispersed in the continuous phase of the matting masterbatch in a melt state. After holding at 120℃ for 10-60 minutes, the homopolymer polyethylene begins to crystallize. Due to volume shrinkage and uneven stress, a rough morphology appears at the interface between the homopolymer polyethylene and the matting masterbatch phases. This leads to an increase in the surface roughness of the matting layer, an increase in haze, and a decrease in light transmittance. The prepared BOPE matting film has a good matting effect. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the structure of the BOPE matte film prepared in Example 1. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This application provides a BOPE matting film and its preparation method, which solves the problem of poor matting effect of existing BOPE matting films. The prepared BOPE matting film has a low film breakage rate and a better matting effect.

[0030] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0031] This application provides a method for preparing a BOPE matte film, comprising the following steps:

[0032] (1) Prepare raw materials for the upper surface layer, the first surface layer, the core layer, the second surface layer and the matte layer respectively. The matte layer raw materials include matte masterbatch and homopolymer polyethylene. The mass ratio of the matte masterbatch and homopolymer polyethylene is 80-90:10-20.

[0033] (2) The five layers of raw materials, namely the upper surface layer, the first surface layer, the core layer, the second surface layer and the matte layer, are co-extruded and cast to form a cast sheet. The cast sheet is kept at 200°C for 10 min-60 min and then kept at 120°C for 10 min-60 min.

[0034] The matte layer is in contact with air;

[0035] The temperature of each section of the extruder for the upper surface layer, the first surface layer, the core layer, and the second surface layer is 245-255℃; the temperature of each section of the extruder for the matte layer is 210-220℃.

[0036] (3) After being subjected to longitudinal stretching and transverse stretching processes, a BOPE matte film is formed.

[0037] The matting layer raw materials include matting masterbatch, homopolymer polyethylene, and silica, with a mass ratio of 30-80:10-20:0.1-10. During processing, the matting masterbatch is the continuous phase, while homopolymer polyethylene and silica are the dispersed phases. After holding at 200℃ for 10-60 minutes, the matting masterbatch begins to crystallize. Due to volume shrinkage and uneven stress, a rough surface morphology appears at the interface between the matting masterbatch and silica. The homopolymer polyethylene is distributed in a melt-like state within the continuous phase of the matting masterbatch. After holding at 120℃ for 10-60 minutes, the homopolymer polyethylene begins to crystallize. Due to volume shrinkage and uneven stress, a rough surface morphology appears at the interface between the homopolymer polyethylene and the matting masterbatch and / or the homopolymer polyethylene and silica. This increases the surface roughness of the matting layer, increases its haze, and decreases its light transmittance, thereby improving the matting effect of the prepared BOPE matting film.

[0038] The temperature of the matte layer extruder is relatively low, and the die lip does not stick to the material, making it less likely for the film to break during the production of BOPE matte film.

[0039] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0040] Example 1:

[0041] This embodiment provides a method for preparing a BOPE matte film, including the following steps:

[0042] (1) Mix 93 parts of homopolymer polyethylene and 7.0 parts of anti-sticking agent evenly in a mixer to obtain the upper surface layer raw material; provide homopolymer polyethylene as the first surface layer and second surface layer raw material; mix 98 parts of homopolymer polyethylene and 2.0 parts of anti-sticking agent evenly in a mixer to obtain the core layer raw material; mix 75 parts of matte masterbatch and 15 parts of homopolymer polyethylene evenly in a mixer to obtain the matte layer raw material.

[0043] (2) A five-layer co-extrusion casting machine is used to co-extrude and cast five layers of raw materials: upper surface layer, first surface layer, core layer, second surface layer, and matte layer, to form a cast sheet. During casting, a five-layer co-extrusion mode is adopted, that is, the upper surface layer is in contact with the casting roller at the bottom, and the matte layer is in contact with the air at the top. The temperature of the first section of the upper surface layer extruder is 245℃, the temperature of the second section is 250℃, the temperature of the third section is 255℃, the temperature of the fourth section is 255℃, and the die temperature is 255℃. The temperatures of each section and the die of the first surface layer, core layer, and second surface layer extruder are the same as those of the upper surface layer extruder. The temperature of the first section of the matte layer extruder is 210℃, the temperature of the second section is 215℃, the temperature of the third section is 220℃, the temperature of the fourth section is 220℃, and the die temperature is 220℃. The cast sheet is held at 200℃ for 10 minutes, and then held at 120℃ for 10 minutes.

[0044] (3) The film undergoes longitudinal stretching and transverse stretching processes sequentially. The longitudinal stretching process is as follows: preheating temperature 100℃, stretching temperature 80℃, stretching ratio 3.8, and setting temperature 110℃. The transverse stretching process is as follows: preheating temperature 120℃, stretching temperature 115℃, stretching ratio 6, and setting temperature 125℃, forming a BOPE matte film. Its structural schematic diagram is shown below. Figure 1 .

[0045] The thickness of the BOPE matte film is 15μm, and the thickness of the matte layer is 0.5μm.

[0046] Example 2

[0047] This embodiment provides a method for preparing a BOPE matte film, including the following steps:

[0048] (1) Mix 94 parts of homopolymer polyethylene and 6.0 parts of anti-sticking agent evenly in a mixer to obtain the upper surface layer raw material; provide homopolymer polyethylene as the first surface layer and second surface layer raw material; mix 98.5 parts of homopolymer polyethylene and 1.5 parts of anti-sticking agent evenly in a mixer to obtain the core layer raw material; mix 80 parts of matte masterbatch, 10 parts of homopolymer polyethylene and 10 parts of silica evenly in a mixer to obtain the matte layer raw material.

[0049] (2) A five-layer co-extrusion casting machine is used to co-extrude and cast five layers of raw materials: upper surface layer, first surface layer, core layer, second surface layer, and matte layer, to form a cast sheet. During casting, a five-layer co-extrusion mode is used, meaning the upper surface layer is in contact with the casting rollers at the bottom, and the matte layer is in contact with the air at the top. The temperatures of the first section of the upper surface layer extruder are 245℃, the second section is 250℃, the third section is 255℃, the fourth section is 255℃, and the die temperature is 255℃. The temperatures of each section and the die of the first surface layer, core layer, and second surface layer extruders are the same as those of the upper surface layer extruder.

[0050] The temperature of the first section of the matte layer extruder is 210℃, the temperature of the second section is 215℃, the temperature of the third section is 220℃, the temperature of the fourth section is 220℃, the die temperature is 220℃, the cast sheet is kept at 200℃ for 40 minutes, and then kept at 120℃ for 40 minutes.

[0051] (3) The film is subjected to longitudinal stretching and transverse stretching in sequence. The longitudinal stretching process is as follows: the preheating temperature is 110℃, the stretching temperature is 90℃, the stretching ratio is 3.9, and the setting temperature is 120℃. The transverse stretching process is as follows: the preheating temperature is 130℃, the stretching temperature is 120℃, the stretching ratio is 7, and the setting temperature is 135℃, thus forming a BOPE matte film.

[0052] The thickness of the BOPE matte film is 20μm, and the thickness of the matte layer is 2μm.

[0053] Example 3

[0054] This embodiment provides a method for preparing a BOPE matte film, including the following steps:

[0055] (1) Mix 95 parts of homopolymer polyethylene and 5.0 parts of anti-sticking agent evenly in a mixer to obtain the upper surface layer raw material; provide homopolymer polyethylene as the first surface layer and second surface layer raw material; mix 99 parts of homopolymer polyethylene and 1.0 parts of anti-sticking agent evenly in a mixer to obtain the core layer raw material; mix 30 parts of matte masterbatch, 10 parts of homopolymer polyethylene and 0.5 parts of silica evenly in a mixer to obtain the matte layer raw material.

[0056] (2) A five-layer co-extrusion casting machine is used to co-extrude and cast five layers of raw materials: upper surface layer, first surface layer, core layer, second surface layer, and matte layer, to form a cast sheet. During casting, a five-layer co-extrusion mode is adopted, that is, the upper surface layer is in contact with the casting roller at the bottom, and the matte layer is in contact with the air at the top. The temperature of the first section of the upper surface layer extruder is 245℃, the temperature of the second section is 250℃, the temperature of the third section is 255℃, the temperature of the fourth section is 255℃, and the die temperature is 255℃. The temperatures of each section and the die of the first surface layer, core layer, and second surface layer extruder are the same as those of the upper surface layer extruder. The temperature of the first section of the matte layer extruder is 210℃, the temperature of the second section is 215℃, the temperature of the third section is 220℃, the temperature of the fourth section is 220℃, and the die temperature is 220℃. The cast sheet is held at 200℃ for 60 minutes, and then held at 120℃ for 60 minutes.

[0057] (3) The film is subjected to longitudinal stretching and transverse stretching in sequence. The longitudinal stretching process is as follows: the preheating temperature is 115℃, the stretching temperature is 95℃, the stretching ratio is 4.0, and the setting temperature is 125℃. The transverse stretching process is as follows: the preheating temperature is 135℃, the stretching temperature is 130℃, the stretching ratio is 8, and the setting temperature is 140℃, thus forming a BOPE matte film.

[0058] The thickness of the BOPE matte film is 25μm, and the thickness of the matte layer is 2.5μm.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that: no homopolymer polyethylene is added to the matte layer; the extruder temperatures for the matte layer are 225°C for the first stage, 230°C for the second stage, 235°C for the third stage, 235°C for the fourth stage, and 235°C for the die opening. Everything else is the same as in Example 1.

[0061] Comparative Example 2

[0062] The difference between Comparative Example 2 and Example 1 is that no homopolymer polyethylene is added to the matte layer, and the extruder temperatures for the matte layer are 210°C for the first stage, 215°C for the second stage, 220°C for the third stage, 220°C for the fourth stage, and 220°C for the die. Everything else is the same as in Example 1.

[0063] The haze and transmittance of the BOPE matte films prepared in Examples 1-3 and Comparative Examples 1 and 2 were tested. The test results are shown in Table 1. The test methods are as follows:

[0064] Haze: According to ASTM D 1003 standard,

[0065] Light transmittance: in accordance with ASTM D 2457 standard.

[0066] Table 1. Test results of the prepared BOPE matting film

[0067] BOPE matte film Haze (%) Light transmittance (%) Number of membrane breaks Example 1 32.2 92.1 1 Example 2 36.3 90.2 0 Example 3 34.8 91.3 0 Comparative Example 1 33.4 91.8 7 Comparative Example 2 16.8 95.9 1

[0068] As shown in Table 1, the matte film prepared in Comparative Example 1 does not contain homopolymer polyethylene in the matte layer. However, the extruder temperature of the first stage is 225℃, the second stage is 230℃, the third stage is 235℃, the fourth stage is 235℃, and the die temperature is 235℃. The higher temperature increases the crystallinity of the matte layer, improves the surface roughness and haze, and makes the matte film of BOPE have a good matte effect. However, due to the high extruder temperature, the die lip is prone to material snagging, which leads to an increase in the number of times the film breaks.

[0069] In Comparative Example 2, the matte film did not contain homopolymer polyethylene. The extruder temperatures for the matte layer were 210℃ in the first stage, 215℃ in the second stage, 220℃ in the third stage, and 220℃ in the fourth stage, with a die temperature of 220℃. Due to the low extruder temperature, material did not adhere to the die lip, reducing the number of film breakages. However, the low temperature also reduced the crystallinity of the matte layer, consequently decreasing its surface roughness and haze, resulting in a poorer matte finish for the BOPE matte film.

[0070] The matte film prepared in Example 1 includes a matte masterbatch and homopolymer polyethylene in the matte layer. Increased surface roughness of the matte layer leads to increased haze and decreased light transmittance, resulting in a good matte effect for the prepared BOPE matte film. The extruder temperatures for the matte layer are 210℃ in the first stage, 215℃ in the second stage, 220℃ in the third stage, and 220℃ in the fourth stage, with a die temperature of 220℃. Due to the low extruder temperature, material does not adhere to the die lip, significantly reducing the number of film breakages.

[0071] In Examples 2 and 3, the matting layer also includes silica. During processing, the matting masterbatch is the continuous phase, while homopolymer polyethylene and silica are the dispersed phases. After holding at 200°C for 10-60 minutes, the matting masterbatch begins to crystallize. Due to volume shrinkage and uneven stress, a rough surface morphology appears at the interface between the matting masterbatch and silica. Homopolymer polyethylene is distributed in a melt-like state within the continuous phase of the matting masterbatch. After holding at 120°C for 10-60 minutes, the homopolymer polyethylene begins to crystallize. Due to volume shrinkage and uneven stress, a rough surface morphology appears at the interface between the homopolymer polyethylene and the matting masterbatch and / or the homopolymer polyethylene and silica. This increases the surface roughness of the matting layer, increases the haze of the matting layer, and decreases the light transmittance. The prepared BOPE matting film has a better matting effect compared to that of Example 1.

[0072] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a BOPE matte film, characterized in that, Includes the following steps: (1) Prepare raw materials for the upper surface layer, the first surface layer, the core layer, the second surface layer, and the matte layer respectively; the raw materials for the matte layer include matte masterbatch, homopolymer polyethylene, and silica, and the mass ratio of the matte masterbatch, homopolymer polyethylene, and silica is 30-80:10-20:0.1-10; the matte masterbatch is a continuous phase, and the homopolymer polyethylene is a dispersed phase; (2) The five layers of raw materials, namely the upper surface layer, the first surface layer, the core layer, the second surface layer and the matte layer, are co-extruded and cast to form a cast sheet. The cast sheet is kept at 200°C for 10 min to 60 min, and the matte masterbatch begins to crystallize. Then, it is kept at 120°C for 10 min to 60 min, and the homopolymer polyethylene begins to crystallize. The matte layer is in contact with air; (3) The film is formed by longitudinal stretching and transverse stretching.

2. The preparation method according to claim 1, characterized in that, The raw materials for the upper surface layer include homopolymer polyethylene and anti-adhesive, wherein the mass ratio of homopolymer polyethylene to anti-adhesive is 93-95:5.0-7.

0.

3. The preparation method according to claim 1, characterized in that, The raw materials for the first and second surface layers include homopolymer polyethylene.

4. The preparation method according to claim 1, characterized in that, The raw materials for the core layer include homopolymer polyethylene and anti-adhesive, wherein the mass ratio of homopolymer polyethylene to anti-adhesive is 98-99:1.0-2.

0.

5. The preparation method according to claim 1, characterized in that, The longitudinal stretching process is as follows: preheating temperature is 100-115℃, stretching temperature is 80-95℃, stretching ratio is 3.8-4.0, and setting temperature is 110-125℃.

6. The preparation method according to claim 1, characterized in that, The transverse stretching process is as follows: preheating temperature is 120-135℃, stretching temperature is 115-130℃, stretching ratio is 6-8, and setting temperature is 125-140℃.

7. A BOPE matte film prepared by the preparation method according to any one of claims 1-6, characterized in that, The matte film comprises, from top to bottom, an upper surface layer, a first surface layer, a core layer, a second surface layer, and a matte layer.

8. The BOPE matte film as described in claim 7, characterized in that, The thickness of the BOPE matte film is 15-25 μm, and the thickness of the matte layer is 0.5-2.5 μm.

9. The BOPE matte film as described in claim 7, characterized in that, The thickness of the matte layer accounts for 2-15% of the total thickness of the BOPE matte film.

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