General CPP film and preparation method thereof

Abstract

The invention relates to the field of general CPP films, in particular to a general CPP film and a preparation method thereof. The general CPP film is prepared from the following raw materials in parts by mass: 95-105 parts of polypropylene resin, 1-5 parts of filler, 1-2 parts of an anti-blocking agent, 1-2 parts of a slipping agent, 0.1-2 parts of a transparent agent and 5-15 parts of compound cellulose, the preparation raw materials of the composite cellulose at least comprise jute and palm leaves, and the mass ratio of the jute to the palm leaves is 1: (0.8-1.2). The mechanical property can be further improved under the condition that the transparency of the general CPP film is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of universal CPP films, and more specifically, to a universal CPP film and a preparation method thereof. Background Art

[0002] General CPP (General Cast Polypropylene) film, also known as general cast polypropylene film, is a type of polypropylene (PP) film produced by cast extrusion in the plastics industry. CPP film is a non-oriented film. Unlike biaxially oriented polypropylene (BOPP) film, it is only oriented to a certain extent in the longitudinal (MD) direction, which is mainly due to the nature of the process. Through rapid cooling on chilled rolls, CPP film can form excellent clarity and finish.

[0003] General CPP film has many excellent properties, such as low cost, high output, good stiffness, high transparency, excellent barrier properties, low heat sealing temperature, heat resistance, moisture resistance, etc. These characteristics make CPP film have a wide range of application prospects in the fields of packaging, printing and composite film.

[0004] Nowadays, as the market's requirements for packaging material performance continue to increase, CPP film needs to continuously improve its mechanical properties to adapt to a wider range of applications. For example, in the fields of food packaging, medical packaging, electronic product packaging, etc., there are high requirements for the mechanical properties of packaging materials. The improvement of mechanical properties can reduce the breakage rate of CPP film during production, transportation and use, thereby reducing production costs and waste. Summary of the invention

[0005] In order to further improve the mechanical properties of the universal CPP film, the present application provides a universal CPP film and a preparation method thereof.

[0006] In the first aspect, the present application provides a universal CPP film, which adopts the following technical solution: A general CPP film comprises the following raw materials by weight: 95-105 parts of polypropylene resin, 1-5 parts of filler, 1-2 parts of anti-blocking agent, 1-2 parts of lubricating agent, 0.1-2 parts of transparent agent, and 5-15 parts of composite cellulose; The raw materials for preparing the composite cellulose at least include jute and palm leaves, and the mass ratio of the jute to the palm leaves is 1:(0.8-1.2).

[0007] Preferably, the filler comprises PE masterbatch.

[0008] By adopting the above technical solutions, in order to ensure the tight combination between plant fibers and CPP matrix resin, jute and palm leaves are mixed and extracted together to prepare composite cellulose, forming an intertwined complex network structure, which can effectively improve the polarity of the fiber surface, change the microstructure of the fiber, and enhance its interaction with resin molecules. The improvement of this interfacial compatibility helps the composite cellulose to form a stable network structure in the film and better transmit stress.

[0009] The intersection points between the composite cellulose become stress concentration areas. In these areas, the tight combination between the composite cellulose and polypropylene resin and the strength of the composite cellulose itself jointly bear the external load, thus protecting the overall structure of the general CPP film from damage.

[0010] In the second aspect, the present application provides a method for preparing a general CPP film, adopting the following technical solutions: A method for preparing a general CPP film includes the following steps: Step 1: Prepare composite cellulose, including the following steps: Step 1a: Place jute and palm leaves in a mixed solution of benzene and alcohol, and extract for 3 - 4 h under the condition of 100 - 110 °C; after taking out, dry to obtain the extract. Step 1b: Mix and soak the extract with sodium hypochlorite, glacial acetic acid, and water for 3 - 4 h under the condition of 60 - 70 °C; after taking out, dry to obtain the first treated product. Step 1c: Mix and soak the treated product with an alkali solution for 3 - 4 h under the condition of 100 - 110 °C; filter to obtain the second treated product; Step 1d: Acid-wash the second treated product to neutral, dry and grind to obtain composite cellulose. Step 2: Melt and mix polypropylene resin, filler, antiblocking agent, slip agent, clarifying agent, and composite cellulose to granulate and obtain pellets. Step 3: The pellets are melt-extruded, cast, cooled and shaped, and drawn to obtain a general CPP film.

[0011] By adopting the above technical solutions, composite cellulose is prepared by a specific method, so that the obtained composite cellulose has high transparency. When applied in a CPP film, it can not only not affect the transparency of the CPP, but also improve its mechanical properties.

[0012] First, in the treatment of the mixed solution of jute, palm leaves, and benzene and alcohol, the mixed solution of benzene and alcohol has good solubility and permeability, and can effectively extract non-cellulose components such as resin, wax, and fat in plant fibers, as well as part of hemicellulose and lignin. The removal of these components helps the purification and transparency of cellulose in subsequent treatments. The extracted material is dried to obtain an extract rich in cellulose.

[0013] Next, in the treatment of mixing the extract with sodium hypochlorite, glacial acetic acid, and water, sodium hypochlorite has strong oxidizing properties and can further remove impurities and pigments in the fiber, while promoting the dissociation and purification of cellulose. The addition of glacial acetic acid helps to adjust the pH value of the solution, making the reaction milder and more controllable, and achieving further purification.

[0014] Then, in the treatment of the first treated product with an alkali solution, the alkali treatment is one of the key steps in cellulose preparation. It can loosen plant fibers, remove non-fiber parts (such as lignin, pectin, etc.), and promote the separation and purification of cellulose. In addition, the alkali treatment can also destroy the crystalline structure of cellulose, making it easier to dissolve and become transparent. The second treated product obtained after filtration has a higher cellulose content and a reduced crystallinity. After a series of treatments, composite cellulose with high transparency and mechanical properties is finally obtained.

[0015] Preferably, the jute and palm leaves are crushed to 200 - 300 mesh before extraction in step 1a.

[0016] Preferably, in step 1a, the jute and palm leaves are placed in a benzene-alcohol mixed solution and mixed at 1500 - 2000 r / min for 10 - 20 min, and then extraction is carried out.

[0017] By adopting the above technical solution, the powdery jute and palm leaves are mixed evenly at a specific high speed, are not easily agglomerated, are more convenient for subsequent preparation of composite cellulose, and improve the quality of composite cellulose.

[0018] Preferably, the mass ratio of the extract to sodium hypochlorite, glacial acetic acid, and water is 1:(0.1 - 1):(0.05 - 0.5):(10 - 15).

[0019] By adopting the above technical solution, further limiting the mass ratio of the extract to sodium hypochlorite, glacial acetic acid, and water can more fully remove impurities and pigments in the fiber, making the transparency of the subsequent obtained composite cellulose higher.

[0020] Preferably, the alkali solution is a 5 - 10 wt% sodium hydroxide solution or potassium hydroxide solution.

[0021] Preferably, the mass ratio of the treated product to the alkali solution is 1:(5 - 10).

[0022] By adopting the above technical solution, further limiting the type of the alkali solution and the mass ratio between the treated product can more fully remove non-fiber parts, making the composite cellulose have higher quality to better improve the performance of the CPP film.

[0023] In summary, the present application has the following beneficial effects: 1. Since this application uses jute and palm leaves to extract and prepare composite cellulose, forming a complex intertwined network, it effectively improves the surface polarity and microstructure of the fibers. When applied to the preparation of CPP films, it can enhance its interaction with the matrix resin and improve the interfacial compatibility. A stable network is formed in the film, and the stress is concentrated and transmitted through the intersection points. The composite cellulose and the resin are tightly combined to jointly bear the external load, protecting the overall structure of the CPP film from damage and improving the mechanical properties.

[0024] 2. This application conducts special treatment on jute and palm leaves, not only removing impurities such as pigments but also retaining the excellent properties of cellulose. The obtained composite cellulose has extremely high transparency. When applied to CPP (cast polypropylene) films, it not only maintains the original transparency of CPP but also significantly enhances the mechanical properties of the film. Detailed implementation mode

[0025] The following further elaborates on this application in conjunction with examples.

[0026] The raw materials used in the following examples and comparative examples are all commercially available products. Examples

[0027] Example 1 A general CPP film includes the following preparation raw materials: polypropylene resin, filler, antiblocking agent, slip agent, clarifying agent, composite cellulose.

[0028] The specific dosage of each raw material is shown in Table 1.

[0029] The polypropylene resin is commercially available, specifically Hengli Petrochemical, L5E89.

[0030] The filler is a PE color masterbatch, purchased from Dongguan Jin Cai New Materials Co., Ltd.

[0031] The antiblocking agent is commercially available, purchased from Dongguan Donglai Plastic Co., Ltd., GE-2.

[0032] The clarifying agent is commercially available, purchased from Suzhou Ju'an Hui Plastic Co., Ltd., with the product number 70G33HS1L.

[0033] The slip agent is commercially available, purchased from Shaoguan Runbo Trading Co., Ltd.

[0034] The preparation raw materials of the composite cellulose include jute and palm leaves, and the mass ratio of jute to palm leaves is 1:(0.8 - 1.2).

[0035] This example also provides a preparation method for a general CPP film, including the following steps: Including the following steps: Step 1: Prepare composite cellulose, including the following steps: Step 1a: Prepare jute and palm leaves in a mass ratio of 1:1. Put them into a grinder and grind them into 250 mesh powder.

[0036] Step 1b: Then put the beaten powder (jute, palm leaves) into the benzene alcohol mixed solution and then mix it at 1800r / min for 15min.

[0037] The benzene-alcohol mixed solution is prepared by mixing benzene and anhydrous ethanol in a volume ratio of 2:1.

[0038] The mass ratio of the total mass of jute and palm leaves to the benzene alcohol mixed solution is 1:5.

[0039] Step 1c: Extract the material from step 1b in a water bath at 105°C for 3.5h.

[0040] After taking out, dry it in an oven to constant weight to obtain an extract.

[0041] Step 1d: prepare materials according to the mass ratio of extract to sodium hypochlorite, glacial acetic acid and water of 1:0.5:0.1:12.

[0042] Sodium hypochlorite, glacial acetic acid and water were mixed, and then the extract was put into a mixed solution of sodium hypochlorite, glacial acetic acid and water, and mixed and soaked at 65°C for 3.5 hours.

[0043] After being taken out, the product is washed with clean water until it becomes neutral, and then dried in an oven until it becomes constant weight to obtain a first processed product.

[0044] Step 1e: Put the treated object into an 8 wt % alkaline solution (sodium hydroxide solution), the mass ratio of the treated object to the alkaline solution is 1:8, and mix and soak for 3.5 hours at 105° C.

[0045] After the soaking is completed, the solid and liquid are separated, and the solid part is the second processed product; Step 1f: The second treated product is acid-washed with hydrochloric acid to neutrality.

[0046] Then it is placed in an oven to dry to constant weight, and then ground to obtain composite cellulose.

[0047] Step 2: Put the polypropylene resin, filler, anti-blocking agent, lubricant, transparent agent and composite cellulose into a mixer, heat and melt at 220°C and mix thoroughly.

[0048] Then extrusion granulation is performed to obtain pellets.

[0049] Step 3: The pellets are melted at 230°C and then extruded and cast.

[0050] Then cool down to 40°C for cooling and shaping, and maintain for 60 minutes. Then cool down to 25°C for cooling and shaping, and maintain for 60 minutes.

[0051] Perform traction at a traction rate of 80 m / min, wind up and cut to obtain a general CPP film.

[0052] Example 2 A general CPP film, which is different from that in Example 1 in that the specific dosages of each raw material are different, as shown in Table 1 for details.

[0053] The raw materials for preparing the composite cellulose include jute and palm leaves, and the mass ratio of jute to palm leaves is 1:0.8.

[0054] In the preparation method of the composite cellulose, some parameters are different, specifically including the following steps: Step 1a: Prepare jute and palm leaves according to the mass ratio of 1:0.8. Put them into a pulverizer and pulverize them into 200-mesh powder.

[0055] Step 1b: Then put the pulverized powder (jute and palm leaves) into the benzene-ethanol mixed solution, and then mix for 20 minutes under the condition of 1500 r / min.

[0056] The benzene-ethanol mixed solution is composed of benzene and absolute ethanol mixed in a volume ratio of 2:1.

[0057] The mass ratio of the total mass of jute and palm leaves to the mass of the benzene-ethanol mixed solution is 1:5.

[0058] Step 1c: Extract the material in Step 1b in a water bath at 100°C for 4 hours.

[0059] After taking it out, dry it in an oven until it reaches a constant weight to obtain the extract.

[0060] Step 1d: Prepare materials according to the mass ratio of the extract to sodium hypochlorite, glacial acetic acid, and water of 1:0.1:0.05:10.

[0061] Mix sodium hypochlorite, glacial acetic acid, and water, and then put the extract into the mixed solution of sodium hypochlorite, glacial acetic acid, and water, and mix and soak for 4 hours under the condition of 60°C.

[0062] After taking it out, wash it with clear water until it is neutral, and then dry it in an oven until it reaches a constant weight to obtain the first treated material.

[0063] Step 1e: Put the treated material into a 5wt% alkali solution (sodium hydroxide solution), and the mass ratio of the treated material to the alkali solution is 1:5. Mix and soak for 4 hours under the condition of 100°C.

[0064] After the soaking is completed, perform solid-liquid separation, and the solid part is the second treated material; Step 1f: Pickle the second treated product with hydrochloric acid until it is neutral.

[0065] Then place it in an oven and dry it to a constant weight, and then grind it to obtain composite cellulose.

[0066] Example 3 A general CPP film, which is different from that in Example 1 in that the specific dosages of each raw material are different, as shown in Table 1 for details.

[0067] The raw materials for preparing the composite cellulose include jute and palm leaves, and the mass ratio of jute to palm leaves is 1:1.2.

[0068] In the preparation method of the composite cellulose, some parameters are different, specifically including the following steps: Step 1a: Prepare jute and palm leaves according to a mass ratio of 1:1.2. Put them into a pulverizer and pulverize them into 300-mesh powder.

[0069] Step 1b: Then put the pulverized powder (jute and palm leaves) into a benzene-ethanol mixed solution, and then mix it at 2000 r / min for 10 min.

[0070] The benzene-ethanol mixed solution is composed of benzene and absolute ethanol mixed at a volume ratio of 2:1.

[0071] The mass ratio of the total mass of jute and palm leaves to the mass of the benzene-ethanol mixed solution is 1:5.

[0072] Step 1c: Extract the material in Step 1b in a water bath at 110 °C for 3 h.

[0073] After taking it out, dry it to a constant weight in an oven to obtain an extract.

[0074] Step 1d: Prepare materials according to the mass ratio of the extract to sodium hypochlorite, glacial acetic acid, and water of 1:1:0.5:15.

[0075] Mix sodium hypochlorite, glacial acetic acid, and water, and then put the extract into the mixed solution of sodium hypochlorite, glacial acetic acid, and water, and mix and soak it at 70 °C for 3 h.

[0076] After taking it out, wash it with clean water until it is neutral, and then dry it to a constant weight in an oven to obtain a first treated product.

[0077] Step 1e: Put the treated product into a 10 wt% alkali solution (potassium hydroxide solution), and the mass ratio of the treated product to the alkali solution is 1:10. Mix and soak it at 110 °C for 3 h.

[0078] After the soaking is completed, perform solid-liquid separation, and the solid part is the second treated product; Step 1f: Pickle the second treated product with hydrochloric acid until it is neutral.

[0079] Then it is placed in an oven and dried to constant weight, and then ground to obtain composite cellulose.

[0080] Table 1 Category Example 1 Example 2 Example 3 Polypropylene resin (kg) 100 95 105 Filler (kg) 2 1 5 Anti-blocking agent (kg) 1.6 1 2 Slip agent (kg) 1.2 1 2 Clarifying agent (kg) 1 0.1 2 Compound cellulose (kg) 10 5 15 Comparative example Comparative example 1 A general CPP film, which is different from Example 1 in that in the raw materials for preparing the composite cellulose, jute is replaced by palm leaves.

[0081] Comparative example 2 A general CPP film, which is different from Example 1 in that in the raw materials for preparing the composite cellulose, palm leaves are replaced by jute.

[0082] Comparative example 3 A general CPP film, which is different from Example 1 in that in the raw materials for preparing the composite cellulose, the mass ratio of jute to palm leaves is 1:0.1.

[0083] Comparative example 4 A general CPP film, which is different from Example 1 in that the composite cellulose is a mixture of commercially available jute fibers and commercially available palm fibers with a mass ratio of 1:1.

[0084] Omit step 1, and after crushing the commercially available jute fibers and commercially available palm fibers to 250 mesh, proceed to step 2.

[0085] The jute fibers are purchased from Chenzhou Xiangnan Jute Industry Co., Ltd.

[0086] The palm fibers are purchased from Dongguan Renfan Supply Chain Management Co., Ltd.

[0087] Comparative example 5 A general CPP film, which is different from Example 1 in that the composite cellulose is omitted.

[0088] Performance detection test 1. Transparency: Refer to GB / T 2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics" to test the light transmittance of the general CPP films of Examples 1-3 and Comparative Examples 1-5, and record the light transmittance in Table 2.

[0089] 2. Mechanical properties: Refer to GB / T 1040.3-2006 "Determination of Tensile Properties of Plastics - Part 3: Test Conditions for Films and Sheets" to detect the tensile strength and elongation at break of the general CPP films of Examples 1-3 and Comparative Examples 1-5, and record the tensile strength and elongation at break in Table 2.

[0090] Table 2 Comparative Example 4 was based on Example 1, simulating the direct addition of commercially available jute fibers and palm fibers; Comparative Example 5 was based on Example 1, omitting the composite cellulose. According to the comparison of the test data in Table 2, the general CPP films of Examples 1-3 had higher light transmittance, tensile strength, and elongation at break than Comparative Example 4, indicating that the general CPP films of Examples 1-3 had better mechanical properties and transparency than Comparative Example 4. Although Comparative Example 5 had a high transparency similar to that of Examples 1-3, the data on its mechanical properties was much lower than that of Examples 1-3. This shows that omitting the composite cellulose or directly using commercially available cellulose cannot make the general CPP film have both high transparency and high mechanical properties.

[0091] Comparative Examples 1-3 were based on Example 1, arbitrarily changing either the raw materials for preparing the composite cellulose or the special mixing ratio between the two. According to the test data in Table 2, the light transmittance of Comparative Examples 1-3 was lower than that of Example 1, although the degree of decrease was not serious; however, the mechanical properties of the general CPP films in Comparative Examples 1-3 decreased significantly and could not reach the level of Example 1. This shows that the raw materials for preparing the composite cellulose and the special mixing ratio between the two have a special combined effect and cannot be changed arbitrarily.

[0092] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A general CPP film, characterized in that: The preparation raw materials include the following in parts by weight: 95-105 parts of polypropylene resin, 1-5 parts of filler, 1-2 parts of anti-blocking agent, 1-2 parts of lubricating agent, 0.1-2 parts of transparent agent, and 5-15 parts of composite cellulose; The raw materials for preparing the composite cellulose at least include jute and palm leaves, and the mass ratio of the jute to the palm leaves is 1:(0.8-1.2).

2. The universal CPP film according to claim 1, characterized in that: The filler includes PE masterbatch.

3. A method for preparing a universal CPP film according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step 1: preparing composite cellulose, comprising the following steps: Step 1a: placing jute and palm leaves in a benzene alcohol mixed solution, extracting at 100-110° C. for 3-4 hours; taking out and drying to obtain an extract; Step 1b: mixing the extract with sodium hypochlorite, glacial acetic acid and water at 60-70° C. and soaking for 3-4 hours; taking out and drying to obtain a first treated product; Step 1c: mixing the treated material with an alkaline solution at 100-110° C. and soaking for 3-4 hours; filtering to obtain a second treated material; Step 1d: acid-washing the second treated product until it is neutral, drying and grinding to obtain composite cellulose; Step 2: melt-mix and granulate the polypropylene resin, filler, opening agent, lubricant, transparent agent and composite cellulose to obtain pellets; Step 3: The pellets are melt-extruded, cast, cooled and shaped, and pulled to obtain a universal CPP film.

4. The method for preparing a universal CPP film according to claim 3, characterized in that: The jute and palm leaves are crushed to 200-300 meshes before extraction in step 1a.

5. The method for preparing a universal CPP film according to claim 3, characterized in that: In the step 1a, jute and palm leaves are placed in a benzene-alcohol mixed solution, mixed at 1500-2000 r / min for 10-20 minutes, and then extracted.

6. The method for preparing a universal CPP film according to claim 3, characterized in that: The mass ratio of the extract to sodium hypochlorite, glacial acetic acid and water is 1:(0.1-1):(0.05-0.5):(10-15).

7. The method for preparing a universal CPP film according to claim 3, characterized in that: The alkaline solution is a 5-10wt% sodium hydroxide solution or a potassium hydroxide solution.

8. The method for preparing a universal CPP film according to claim 7, characterized in that: The mass ratio of the treated material to the alkaline solution is 1:(5-10).

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