Composite film paper material and preparation method thereof

Abstract

The present invention belongs to the technical field of packaging materials, and specifically relates to a composite film-paper material and a preparation method thereof. The composite film-paper material comprises a composite film layer and a paper layer; in terms of weight, the composite film layer comprises 60 to 70 parts of polylactic acid, 20 to 30 parts of polybutylene terephthalate adipate, 5 to 8 parts of polyether polyol, 5 to 8 parts of esterified hydrophobic fumed silica, and 3 to 5 parts of quinoline; the preparation process of the esterified hydrophobic fumed silica comprises the following steps: stirring the fumed silica and acetyl chloride, and drying. The present invention mixes the esterified hydrophobic fumed silica, polylactic acid, quinoline, and polyether polyol in a scientific proportion, and utilizes the hydrophobicity of the esterified hydrophobic fumed silica and the close structure formed between the components to significantly improve the barrier properties of the composite film-paper material without affecting its mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging materials, and in particular relates to a composite film paper material and a preparation method thereof. Background Art

[0002] Composite film and paper materials are packaging materials made by combining two or more different materials through a specific process. They possess excellent physical, chemical, and barrier properties and are widely used in packaging technology for industries such as food, pharmaceuticals, and electronics. Currently, disposable, non-biodegradable plastics commonly used in packaging materials include non-biodegradable polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), and polyethylene terephthalate (PET). Therefore, the use of biodegradable plastics to create composite film and paper is a promising development.

[0003] CN108819411A discloses a packaging material with a barrier function, comprising a barrier layer, a reinforcement layer, a protective layer, and a printed layer. The layers are hot-pressed and laminated with an adhesive. The barrier layer is made of aluminized kraft paper, and the printed layer is made of biaxially oriented polyethylene film. This technical solution has a simple structure, a reasonable design, and a low cost. It has excellent barrier properties, high mechanical strength, and good pressure resistance. However, the material used for the printed layer is biaxially oriented polyethylene film. Although it has good performance, its degradation performance is not ideal, which is contrary to the challenges currently faced by society in the recycling and treatment of plastics. CN112937045A discloses a biodegradable high-barrier composite film material structure and its packaging bag. The composite film material includes, from top to bottom, a cellulose layer, a pure aluminum layer, and a PBAT layer, and the layers are bonded together by adhesive composite film-forming technology. The performance of each film layer in this technical solution is complementary, and a composite film material can be made that has good surface wetting tension, is heat-resistant and heat-sealable, and can adapt to low-temperature freezing and high-barrier conditions. The degradable part has a degradation rate of over 90%, which is energy-saving and environmentally friendly. Although this technical solution uses degradable materials, it still uses aluminum film to composite with other film layers to improve the barrier performance of the composite film. The main means of improving the barrier performance of the composite film in the above two patents is to composite aluminum foil or pure aluminum with other film layers to enhance the barrier ability of the composite film. However, the barrier performance of the composite film using materials such as PBAT and polyethylene alone in combination with other film layers still cannot meet the application requirements of the composite film in the field of packaging material technology.

[0004] Therefore, there is an urgent need to develop a new type of high-barrier composite film that can achieve a high barrier effect without relying on the composite with the aluminum product film layer. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a composite film paper material, wherein the composite film layer has good compatibility and is easy to recycle; and the composite film paper has excellent barrier properties.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A composite film-paper material comprises a composite film layer and a paper layer; the composite film layer comprises the following raw materials in parts by weight: 60-70 parts of polylactic acid, 20-30 parts of polybutylene terephthalate adipate, 5-8 parts of polyether polyol, 5-8 parts of esterified hydrophobic fumed silica, and 3-5 parts of quinoline; the esterified hydrophobic fumed silica is prepared by stirring fumed silica and acetyl chloride and then drying.

[0008] Furthermore, the usage ratio of the fumed silica and acetyl chloride is 1 g: 2-3 mL.

[0009] Furthermore, the stirring temperature is 10-20° C. and the stirring time is 2-3 h.

[0010] Furthermore, the drying temperature is 65-75° C. and the drying time is 2-3 hours.

[0011] Furthermore, the particle size of the fumed silica is 7 to 40 nm.

[0012] Furthermore, the polyether polyol is one of polytetramethylene glycol and polypropylene glycol.

[0013] Furthermore, the molecular weight of the polytetrahydrofuran diol is 250-3000, and the molecular weight of the polypropylene glycol is 1000.

[0014] Furthermore, the molecular weight of the polytetrahydrofuran diol is 1000.

[0015] Furthermore, the weight average molecular weight of the polylactic acid is 20,000-30,000, and the weight average molecular weight of the polybutylene terephthalate adipate is 60,000-80,000.

[0016] Furthermore, the thickness of the composite film layer is 48 μm.

[0017] A second object of the present invention is to provide a method for preparing a composite film paper material.

[0018] One of the purposes of the present invention is achieved by the following technical solution:

[0019] The preparation process of the composite film paper material comprises the following steps:

[0020] (1) mixing esterified hydrophobic fumed silica, polylactic acid, quinoline, and polyether polyol according to the weight ratio, and drying to obtain a mixture;

[0021] (2) adding polybutylene terephthalate adipate to the mixture of step (1), mixing uniformly, and then melting and extruding through a twin-screw extruder, and plasticizing and granulating to obtain a composite film layer;

[0022] (3) Compounding the composite film layer and the paper layer in step (2) to obtain the composite film-paper material.

[0023] The esterified hydrophobic fumed silica, polylactic acid, quinoline, and polyether polyol are stirred for a period of time to allow the components to be fully cross-linked under the action of quinoline, such as cross-linking of the esterified hydrophobic fumed silica with polylactic acid, cross-linking of the polyether polyol with polylactic acid, cross-linking of the esterified hydrophobic fumed silica with polylactic acid and then with polyether polyol, and then melt-mixing with polybutylene terephthalate adipate and granulating.

[0024] Furthermore, in step (1), the stirring temperature is 60-65° C. and the time is 45-60 min; and the drying temperature is 65-75° C. and the time is 2-3 h.

[0025] Furthermore, the compounding process in step (3) includes hot pressing compounding and cold pressing flattening.

[0026] Furthermore, the temperature of the hot pressing is 138-142° C., and the pressure is 0.1-0.4 MPa; the temperature of the cold pressing is 20-25° C., and the pressure is 0.05-0.08 MPa.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention utilizes the active characteristics of the hydroxyl groups on the surface of fumed silica and successfully prepares esterified hydrophobic fumed silica by reacting it with acyl chloride. The present invention mixes esterified hydrophobic fumed silica, polylactic acid, quinoline, and polyether polyol in a scientific ratio. The esterification of the hydrophobic fumed silica can improve its binding with PLA, PBAT, and polyether polyol. Under the action of quinoline, the components can interact through ester exchange to form a compact structure. The hydrophobicity of the esterified hydrophobic fumed silica and the compact structure formed between the components significantly improve the barrier properties of the composite film and paper material without affecting its mechanical properties. DETAILED DESCRIPTION

[0029] Below, in conjunction with specific embodiments, the present invention is further described. It should be noted that, under the premise of no conflict, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0030] Example 1

[0031] A composite film-paper material comprises a composite film layer and a paper layer; the composite film layer comprises the following raw materials in parts by weight: 65 parts of polylactic acid (weight-average molecular weight of 20,000-30,000), 25 parts of polybutylene terephthalate adipate (weight-average molecular weight of 60,000-80,000), 7 parts of polytetramethylene glycol (molecular weight of 1,000), 7 parts of esterified hydrophobic fumed silica, and 4 parts of quinoline.

[0032] The preparation process of the esterified hydrophobic fumed silica comprises the following steps: adding the fumed silica (average particle size of 7 to 40 nm) to acetyl chloride in a ratio of 1 g:2.5 mL, stirring at 15° C. for 2.5 hours, and drying the mixture at 70° C. for 2.5 hours to obtain the esterified hydrophobic fumed silica.

[0033] This embodiment also provides a method for preparing the composite film paper material, comprising the following steps:

[0034] (1) Weighing esterified hydrophobic fumed silica and polytetrahydrofuran diol in a stirrer, stirring evenly, then successively adding polylactic acid and quinoline and stirring at 62 ° C for 52 min, then drying at 70 ° C for 2.5 h to obtain a mixture;

[0035] (2) weighing polybutylene terephthalate adipate and the mixture of step (1) and continuing to mix, and melt-extruded through a twin-screw extruder (30° C., 60° C., 120° C., 140° C., 150° C., 160° C. and 170° C.), and plasticizing and granulating the obtained material to obtain a composite film layer;

[0036] (3) The composite film layer and the paper layer of step (2) were hot-pressed by hot pressing rollers at 140°C and 0.4 MPa for 3 seconds, and then flattened by cold pressing rollers at 22°C and 0.07 MPa to obtain a composite film-paper material. The thickness of the composite film layer was 48 μm.

[0037] Example 2

[0038] A composite film-paper material comprises a composite film layer and a paper layer; the composite film layer comprises 60 parts of polylactic acid (weight-average molecular weight of 20,000-30,000), 20 parts of polybutylene terephthalate adipate (weight-average molecular weight of 60,000-80,000), 5 parts of polypropylene glycol (molecular weight: 1,000), 5 parts of esterified hydrophobic fumed silica, and 3 parts of quinoline.

[0039] The preparation process of the esterified hydrophobic fumed silica comprises the following steps: adding the fumed silica (particle size of 7 to 40 nm) to acetyl chloride in a ratio of 1 g:2 mL, stirring at 10° C. for 3 hours, and drying the mixture at 65° C. for 2 hours to obtain the esterified hydrophobic fumed silica.

[0040] This embodiment also provides a method for preparing the composite film paper material, comprising the following steps:

[0041] (1) Weighing esterified hydrophobic fumed silica and polypropylene glycol and stirring them uniformly in a blender, then sequentially adding polylactic acid and quinoline, stirring at 60° C. for 60 minutes, and then drying at 65° C. for 3 hours to obtain a mixture;

[0042] (2) weighing polybutylene terephthalate adipate and the mixture of step (1) and continuing to mix, and melt-extruded through a twin-screw extruder (30° C., 60° C., 120° C., 140° C., 150° C., 160° C. and 170° C.), and plasticizing and granulating the obtained material to obtain a composite film layer;

[0043] (3) The composite film layer and the paper layer of step (2) were hot-pressed by hot pressing rollers at 138°C and 0.1 MPa for 3 seconds, and then flattened by cold pressing rollers at 20°C and 0.05 MPa to obtain a composite film-paper material. The thickness of the composite film layer was 48 μm.

[0044] Example 3

[0045] A composite film-paper material comprises a composite film layer and a paper layer; the composite film layer comprises 70 parts of polylactic acid (weight-average molecular weight of 20,000-30,000), 30 parts of polybutylene terephthalate adipate (weight-average molecular weight of 60,000-80,000), 8 parts of polytetramethylene glycol (2 parts of polytetramethylene glycol with a molecular weight of 250, 6 parts of polytetramethylene glycol with a molecular weight of 3,000), 8 parts of esterified hydrophobic fumed silica, and 5 parts of quinoline.

[0046] The preparation process of the esterified hydrophobic fumed silica comprises the following steps: adding the fumed silica (particle size of 7 to 40 nm) to acetyl chloride in a ratio of 1 g:3 mL, stirring at 20° C. for 2 hours, and drying the mixture at 75° C. for 3 hours to obtain the esterified hydrophobic fumed silica.

[0047] This embodiment also provides a method for preparing the composite film paper material, comprising the following steps:

[0048] (1) Weighing esterified hydrophobic fumed silica and polyether polyol and stirring them uniformly in a blender, then sequentially adding polylactic acid and quinoline, stirring at 65° C. for 45 minutes, and then drying at 75° C. for 2 hours to obtain a mixture;

[0049] (2) weighing polybutylene terephthalate adipate and the mixture of step (1) and continuing to mix, and melt-extruded through a twin-screw extruder (30° C., 60° C., 120° C., 140° C., 150° C., 160° C. and 170° C.), and plasticizing and granulating the obtained material to obtain a composite film layer;

[0050] (3) The composite film layer and the paper layer of step (2) were hot-pressed by hot pressing rollers at 142°C and 0.2 MPa for 3 seconds, and then flattened by cold pressing rollers at 25°C and 0.08 MPa to obtain a composite film-paper material. The thickness of the composite film layer was 48 μm.

[0051] Comparative Example 1

[0052] A composite membrane paper material, which differs from Example 1 in that the esterified hydrophobic fumed silica in step (1) is replaced by conventional hydrophobic fumed silica (model: HB-151).

[0053] Comparative Example 2

[0054] A composite membrane paper material, which differs from Example 1 in that quinoline in step (1) is omitted.

[0055] Test Example 1

[0056] The composite film and paper materials obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were tested for barrier properties and mechanical properties. The water vapor permeability of each group of film and paper materials was measured in accordance with GB / T1037-88 "Plastic Film and Sheeting Test Method for Water Vapor Permeability - Cup Method" at 38°C and 90% RH. The oxygen permeability of each group of film and paper materials was measured in accordance with GB / T1038-2000 "Plastic Film and Sheeting Gas Permeability - Pressure Differential Method" at 23°C and 0% RH. The tensile strength was tested in accordance with GB / T1040.3-2006 at a test rate of 250 mm / min, as shown in Table 1.

[0057] Table 1 Performance results of the membrane paper materials of Examples 1 to 3 and Comparative Examples 1 to 2

[0058]

[0059] As can be seen from Table 1, the composite film paper materials prepared in Examples 1 to 3 of the present invention have excellent barrier effects, and their barrier effects on oxygen and water vapor are better than those of Comparative Examples 1 to 2, and they also have good tensile strength.

[0060] Comparative Example 1 used conventional commercially available hydrophobic fumed silica, resulting in a slightly lower barrier effect than Example 1. However, due to the poor bonding between the commercially available hydrophobic fumed silica and the substrate, the mechanical properties of the material were somewhat lower than those of Example 1. In Comparative Example 2, no quinoline was added during the preparation of the composite film paper material, resulting in a decrease in the tensile strength of the material.

[0061] Compared to Comparative Examples 1-2, Examples 1-3 of the present invention incorporate esterified hydrophobic fumed silica and quinoline during the preparation of composite film and paper materials. The esterification of the hydrophobic fumed silica enhances its binding properties with PLA, PBAT, and polyether polyol, while the quinoline facilitates interaction between the components, forming a compact structure. Leveraging the hydrophobicity of the esterified hydrophobic fumed silica and the resulting compact structure between the components, the barrier properties of the material are significantly enhanced while maintaining minimal impact on mechanical properties.

[0062] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A composite film paper material, characterized in that: The invention comprises a composite film layer and a paper layer; the composite film layer comprises the following raw materials in parts by weight: 60-70 parts of polylactic acid, 20-30 parts of polybutylene terephthalate adipate, 5-8 parts of polyether polyol, 5-8 parts of esterified hydrophobic fumed silica, and 3-5 parts of quinoline; the esterified hydrophobic fumed silica is prepared by stirring fumed silica and acetyl chloride and then drying.

2. The composite film paper material according to claim 1, characterized in that: The usage ratio of the fumed silica and acetyl chloride is 1 g: (2-3) mL.

3. The composite film paper material according to claim 1, characterized in that: The stirring temperature is 10-20°C and the stirring time is 2-3h.

4. The composite film paper material according to claim 1, characterized in that: The drying temperature is 65-75°C and the drying time is 2-3 hours.

5. The composite film paper material according to claim 1, characterized in that: The particle size of the fumed silica is 7-40 nm.

6. The composite film paper material according to claim 1, characterized in that: The polyether polyol is one of polytetramethylene glycol and polypropylene glycol.

7. The method for preparing a composite film paper material according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing esterified hydrophobic fumed silica, polylactic acid, quinoline, and polyether polyol according to the weight ratio, and drying to obtain a mixture; (2) adding polybutylene terephthalate adipate to the mixture of step (1), mixing uniformly, and then melting and extruding through a twin-screw extruder, and plasticizing and granulating to obtain a composite film layer; (3) Compounding the composite film layer with the paper layer to obtain the composite film-paper material.

8. The method for preparing the composite film paper material according to claim 7, characterized in that: The stirring temperature in step (1) is 60-65°C and the time is 45-60 min; the drying temperature is 65-75°C and the time is 2-3 h.

9. The method for preparing a composite film paper material according to claim 7, characterized in that: The compounding process in step (3) includes hot pressing compounding and cold pressing flattening.

10. The method for preparing a composite film paper material according to claim 9, characterized in that: The temperature of the hot pressing is 138-142° C., and the pressure is 0.1-0.4 MPa; the temperature of the cold pressing is 20-25° C., and the pressure is 0.05-0.08 MPa.

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