Paper-feeling non-woven fabric composite film and preparation method thereof

Abstract

The invention provides a paper-feeling non-woven fabric composite film and a preparation method thereof. The composite film comprises a surface layer, a first extrusion layer, a non-woven fabric layer, a second extrusion layer and a heat sealing layer which are sequentially stacked. The surface layer is made of an OPP, PET or NY film material, the heat sealing layer is made of a CPP or PE film material, the non-woven fabric layer is of an asymmetric cross network structure formed by melting and spinning PE / PP, then carrying out double-die-head cross lapping, and carrying out hot pressing and curing by a three-roller calender unit, and 0.5-2% of nano CaCO3 is added to improve the surface roughness and simulate the touch feeling of paper. During preparation, all the layers are bonded by combining an extrusion process with solvent-free glue, and the composite film has paper touch, environmental protection property and deformation resistance, and is suitable for the field of packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of composite films, in particular to a non-woven composite film, and more particularly to a paper-textured non-woven composite film and a preparation method thereof. Background Art

[0002] Paper-textured nonwovens have a smooth, glossy surface and a certain glossiness. Their texture and appearance are similar to traditional paper, creating a simple and elegant visual experience. Compared to ordinary paper, they are more resistant to deformation due to humidity changes or external forces, maintaining their excellent condition over time.

[0003] However, traditional non-woven composite membranes use an embossing process to create a concave and convex surface, but when the texture depth is greater than 50μm, the tensile strength decreases, the texture disappears after repeated bending, and the paper texture no longer exists. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a non-woven composite film with a convex-concave surface and a paper-like feel, thereby improving the consumer experience.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: A paper-textured non-woven composite film comprising a surface layer, a first extruded layer, a non-woven layer, a second extruded layer and a heat-sealing layer arranged in sequence; The surface layer is selected from one of OPP (oriented polypropylene), PET (polyethylene terephthalate), and NY (nylon, polyamide); The preparation method of the non-woven fabric layer comprises the following steps: melting PE (polyethylene) and / or PP (polypropylene) and spinning them into a fiber web, and then hot-pressing and solidifying the fiber web to obtain a non-woven fabric roll film. The non-woven fabric has a gram weight of 10-30 g / m 2 .

[0006] The heat sealing layer is selected from CPP (cast polypropylene film) and / or PE film; The first extruded layer and the second extruded layer are PE layers extruded and laminated on the upper and lower sides of the non-woven fabric.

[0007] Furthermore, a barrier layer is provided between the second extruded layer and the heat-sealing layer, and is bonded to the adjacent layers using glue. Optionally, the barrier layer comprises a film material such as Al (aluminum foil), MPET (aluminized polyester), or MOPP (monoaxially oriented polypropylene).

[0008] Furthermore, the non-woven fabric layer is formed by melting and hot pressing PE / PP fibers to form a cross-network structure, wherein the angle between the axial direction of the PP fiber and the axial direction of the PE fiber is controlled in the range of 90°-150°, the porosity of the non-woven fabric layer is 30-50%, and the pore connectivity is ≥80%.

[0009] Furthermore, the preparation of the non-woven fabric layer includes: S01, melt blending PE and / or PP with nano-CaCO3; S02, the resin matrix melt-blended and mixed with nano-CaCO3 is cross-laid through a double die head to form a fiber web with a fiber angle; S03, processing the fiber web with the fiber angle by a three-roll calender unit.

[0010] Further, In S01: the weight percentage of nano-CaCO3 in the resin matrix is ​​0.5-2%; In S02, the fiber angle formed by the cross-laying of the two die heads is 90-150°; In S03, the roller temperatures of the three-roll calender unit are: upper roller 120°C; middle roller 145°C; lower roller 100°C, and the line pressure of the three-roll calender unit is 10 kg / cm.

[0011] Furthermore, the PP fibers and the PE fibers are arranged in a staggered manner, wherein the axial directions of the PP fibers and the axial directions of the PE fibers form an asymmetric angle distribution, thereby forming an asymmetric cross-network structure.

[0012] The present invention also provides a method for preparing a non-woven composite membrane having any of the above technical features, comprising: Step 1: Place the surface substrate on the first unwinding unit of the extruder, and place the non-woven fabric substrate on the second unwinding unit of the extruder. The surface layer is coated with a two-component polyurethane glue on the first extrusion layer via a glue roller and then connected to the non-woven fabric layer. Step 2: Place the heat seal layer substrate on the first unwinding unit of the extruder, and place the non-woven fabric layer substrate on the second unwinding unit of the extruder. The heat seal layer passes through the guide roller, and the second extrusion layer of the lamination is connected to the non-woven fabric layer. Step 3: Curing the prepared non-woven composite membrane.

[0013] Further, In step 1, the die head temperature of the first unwinding unit of the extruder is 320-340°C, the die head compounding pressure is 2-5 bar, the unwinding tension is 4-5 kgf, the winding tension is 30-40 kgf, the die head temperature of the second unwinding unit of the extruder is 320-340°C, and the die head compounding pressure is 3-5 bar; In step 2, the die head temperature of the first unwinding unit of the extruder is 320-340°C, the die head compounding pressure is 2-5 bar, the unwinding tension is 4-5 kgf, the winding tension is 30-40 kgf, the die head temperature of the second unwinding unit of the extruder is 320-340°C, and the die head compounding pressure is 3-5 bar; In step 3, the non-woven composite membrane is aged at 40° C. for more than 24 hours.

[0014] Furthermore, the extrusion pressure of the rubber roller on the first extrusion layer and / or the second extrusion layer is 1-3 bar.

[0015] Furthermore, the solvent-free glue adopts two-component polyurethane glue, and the two-component polyurethane glue group includes a main agent, a curing agent and a solvent in a mass ratio of 10:3:15.

[0016] The advantages and beneficial effects of the present invention are: The present invention adopts a surface layer, a first extruded layer, a non-woven fabric layer, a second extruded layer and a heat-sealing layer which are stacked in sequence. The non-woven fabric layer formed by spinning and hot pressing is combined with the extruded layer structure to achieve a good touch of the non-woven composite film and has low VOCs emissions, meeting the requirements of green production.

[0017] The nonwoven fabric layer utilizes PE / PP cross-lapped through a dual die head to create an asymmetric network structure. Micron-scale pores and a three-dimensional, concave-convex surface naturally form between the fibers, simulating the rough feel of paper. The addition of nano-CaCO3 increases the fiber surface roughness. The interfacial effect between the inorganic filler and the resin matrix improves the coefficient of friction and creates a matte finish, enhancing the feel of paper.

[0018] The three-roll calender unit uses hot pressing to avoid high temperature from damaging the fiber structure, and accurately compacts the fiber web through line pressure to form uniform micro-protrusions and depressions, achieving controllable surface texture. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the preparation method of the present invention; Figure 2 It is a structural schematic diagram of the present invention; Figure 3 Schematic diagram of the structure of the non-woven fabric layer of the present invention; Figure 4 It is a product diagram of the present invention; In the figure: 1-surface layer, 2-first extruded layer, 3-non-woven fabric layer, 31-PP fiber, 32-PE fiber, 4-second extruded layer, 5-heat sealing layer. DETAILED DESCRIPTION

[0020] The present invention provides a paper-textured nonwoven composite film and its preparation method, comprising a sequentially stacked surface layer 1, a first extruded layer 2, a nonwoven layer 3, a second extruded layer 4, and a heat-sealing layer 5. The surface layer can be selected based on actual needs, such as OPP for high transparency and stiffness, PET for good temperature resistance and mechanical strength, and NY for excellent flexibility and barrier properties, providing a foundation for both appearance and functionality. The nonwoven layer utilizes a structure formed by melt-spinning PE / PP followed by hot pressing to achieve fiber compaction and micropore control. The extruded layer serves as a bonding transition layer, and through an extrusion lamination process, it combines with glue to achieve a stable, paper-like feel.

[0021] As a preferred embodiment, a barrier layer can be added between the second extruded layer and the heat-sealing layer to form a composite barrier system. The barrier layer can be made of aluminum foil, aluminum-coated film, nylon, silicon-coated film, polyvinylidene chloride film, etc., to provide oxygen and moisture barrier properties for the composite film structure. It is worth noting that in the technical solution of adding a barrier layer, a higher composite pressure and glue should be adopted between the barrier layer and the second extruded layer. Optionally, maleic anhydride-cut polyethylene, ethylene-ethanol copolymer, etc. can be added to reduce the problem of insufficient cross-sectional bonding strength between the barrier layer and other layers.

[0022] As a preferred embodiment, the non-woven fabric layer can be made of PE / PP melt alternately spun through a double die head to form a fiber angle, and then build a three-dimensional cross network to give the non-woven fabric layer anisotropic mechanical properties.

[0023] As a preferred embodiment, the nonwoven fabric layer has a PP / PE blend ratio of 1:1-3:2. PP (40%-60% crystallinity) provides a rigid skeleton, while PE (>70% amorphous regions) imparts flexibility and resilience. Melt blending creates an island-in-the-sea structure. The PP crystalline regions act as "hard islands" to support the surface's micro-bumps, while the PE amorphous regions act as "soft seas" to buffer external forces, simulating the elastic deformation properties of paper under pressure.

[0024] A microphase-separated structure is formed through the difference in glass transition temperatures between the two components. The glass transition temperature of PP (Tg≈-10°C) is significantly higher than that of PE (Tg≈-120°C), resulting in differential shrinkage during hot pressing and curing. When the calendering roller temperature gradient is 120°C → 145°C → 100°C, the shrinkage of PP fibers (0.8-1.2%) is 4-6 times that of PE (0.2-0.5%). This differential shrinkage forces the fiber network to produce three-dimensional curling, forming a microporous structure with a porosity of 30-50%.

[0025] PP fibers and PE fibers are arranged orthogonally (90°±5°) or obliquely (120-150°). The diameter of PP fibers is 15-25μm and that of PE fibers is 20-35μm, forming differentiated fiber bundle spacing. The porosity (30-50%) and pore connectivity are controlled by the fiber axial angle.

[0026] As a preferred embodiment, the nonwoven fabric layer utilizes a dual-die cross-laying system. The present invention provides the following technical parameters: The first die (PP) and the second die (PE) are installed at a 120° angle, creating a 90-150° staggered angle during fiber deposition. Finite element simulations show that this angle produces an asymmetric stress distribution when the fibers are stressed (an X / Y modulus ratio of 1.3:1), suppressing the "plastic feel" associated with isotropy. The distance between the two dies is controlled at 50-100mm, and the airflow velocity is 15-25m / s. This creates an angle between the two fibers during flight, and the second die is offset 30-50mm in height relative to the first die, resulting in staggered deposition.

[0027] As a preferred embodiment, the nonwoven fabric layer can also incorporate nano-CaCO3 particles (D50 = 80nm), accounting for 0.5-2% by mass of the resin matrix, to increase the interfacial roughness of the resin matrix and improve the surface friction coefficient. The resin matrix is ​​formed using a hot-melt spinning and hot-pressing process. Three-roll calendering uses a gradient temperature to prevent fiber melt collapse while precisely compacting the web with linear pressure, forming uniform micro-protrusions with a height of 1-5μm, enhancing the simulated paper texture.

[0028] Here, the nanoparticles form micron-sized (1-5 μm) aggregates in the resin matrix, which trigger Mie scattering, reduce the gloss of the material, and further achieve a matte effect similar to paper.

[0029] In the present invention, there is a technical solution for controlling the fiber angle, which ensures the asymmetry of the fiber network through an angle range of 90-150°. If the angle is too small, the mechanical properties of the fiber network tend to be isotropic, and if the angle is too large, there is a risk of reducing the interlayer bonding strength.

[0030] The present invention further provides an extrusion process preparation method for a non-woven composite membrane having at least any one of the above-mentioned technical features, which uses a temperature of 320-340°C to ensure the melt fluidity of 2-5g / 10min, avoiding material degradation caused by excessive temperature. The lower unwinding tension in the unwinding unit is combined with the higher winding tension to prevent deformation of the substrate while improving the flatness of the surface of the non-woven composite membrane.

[0031] In the process of extrusion compounding of the present invention, when a barrier layer is selected, glue is required to achieve bonding. The glue is preferably a two-component polyurethane glue, and the main agent is a hydroxyl component, including but not limited to ethanol, propanol, etc., which accounts for 10 parts to ensure the continuity of the glue film during the extrusion compounding process. The curing agent is isocyanate, accounting for 3 parts, to achieve an appropriate cross-linking density and avoid the catalysis of the glue layer caused by its excessive amount. Ethyl acetate is used as the solvent as a leveling agent. The viscosity of the two-component polyurethane glue is 3500cps, and it penetrates into the pores of the non-woven fabric under an extrusion pressure of 1-3bar. After the glue is cured, an anchoring structure is formed, thereby improving the interlayer peeling strength.

[0032] The following embodiments are further described in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0033] Example 1 A non-woven fabric composite film is sequentially provided with a surface layer, a first extrusion layer, a non-woven fabric layer, a second extrusion layer and a heat-sealing layer structure.

[0034] The surface layer is 25μm OPP film and the non-woven fabric layer is 18g / m 2 The heat sealing layer is a PE film with a thickness of 30 μm and the heat sealing layer is a CPP film with a thickness of 30 μm.

[0035] The preparation method thereof includes: Step 1: Load the OPP film into the first unwinding unit of the extruder and unwind it at a tension of 4.5 kgf. Load the non-woven fabric layer into the second unwinding unit. The die temperature of the two unwinding units is 330°C, the lamination pressure is 3 bar, and the winding tension is 35 kgf. After preliminary lamination, the film is wound. Step 2: Load the CPP film on the first unwinding unit of the extruder, and place the surface layer / non-woven fabric layer prepared in step 1 on the second unwinding unit. The die head temperature of the two unwinding units is 325° C., and a composite pressure of 4 bar is used.

[0036] Example 2 A non-woven composite membrane, the difference from Example 1 is that the non-woven layer has a gram weight of 30g / m 2 A 12 μm aluminum foil is provided as a barrier layer between the second extrusion layer and the CPP heat sealing layer.

[0037] The difference in the preparation method is that the CPP film in step 2 is replaced with an aluminum foil / CPP composite substrate, and 1.0g / m² of two-component polyurethane glue is applied to the bonding interface of the aluminum foil and CPP. The composite pressure in step 2 is increased to 5 bar and 1.5g / m² of two-component polyurethane glue is applied to ensure the interfacial bonding strength between the aluminum foil and the second extruded layer.

[0038] Example 3 A non-woven composite film, the difference from Example 1 is that the surface layer is made of 25 μm PET film, the heat sealing layer is made of 30 μm PE film, and the non-woven layer is made of 24 g / m 2 PE / PP blend film, wherein the mass ratio of PE / PP is 1:1.

[0039] Example 4 A non-woven composite membrane, which differs from Example 3 only in that the PE / PP fibers of the non-woven layer are arranged orthogonally with an angle of 90°, and nano-CaCO3 is added in an amount of 2% by weight of the total weight of PE and PP.

[0040] Wherein, the preparation method of the non-woven fabric layer is: S01, melt blending PE and / or PP with nano-CaCO3; S02, the resin matrix melt-blended and mixed with nano-CaCO3 is cross-laid through a double die head to form a fiber web with a fiber angle; S03, the fiber web with the fiber angle is processed by a three-roll calender unit. The working parameters of the three-roll calender unit are: upper roller 120°C; middle roller 145°C; lower roller 100°C, and the linear pressure of the three-roll calender unit is 10kg / cm.

[0041] Example 5 A non-woven composite membrane differs from Example 4 only in that the non-woven layer has a PE:PP ratio of 3:2 (mass ratio), and is added with nano-CaCO3 in an amount of 1.2% of the total weight of the resin matrix. After melt blending, the membrane is cross-lapped through a double die head.

[0042] In the preparation method of the composite film, the die temperature in step 1 was adjusted to 340°C, the composite pressure was 5 bar, and the glue amount was 1.5 g / m².

[0043] Example 6 A nonwoven composite membrane differs from Example 4 only in that the surface layer of the composite membrane utilizes a 15μm-thick NY film, and an 8μm-thick MOPP barrier layer is disposed between the second extruded layer and the heat-seal layer. The nonwoven layer utilizes alternating PE / PP fibers arranged orthogonally to form a cross-network structure with a 150° angle. The extrusion pressure between the barrier layer and the second extruded layer reaches 3 bar.

[0044] Example 7 A non-woven composite membrane, the difference from Example 4 is that in step 2, the temperature of the die head is 320 ° C, the composite pressure is 2 bar, the PE / PP ratio of the non-woven layer is 7:3, and 1.0% nano-CaCO3 is added, and the gram weight of the non-woven layer is 15g / m 2 .

[0045] Example 8 A non-woven composite membrane, which differs from Example 4 only in that, in step 1, the die temperature is 340°C, the composite pressure is 5 bar, the non-woven layer is made of PP fiber, 2.0% nano-CaCO3 is added, and the weight of the non-woven layer is 20 g / m 2 .

[0046] Example 9 A non-woven composite membrane, which differs from Example 4 only in that, in step 1, the composite pressure is 3 bar.

[0047] Example 10 A non-woven composite membrane is different from Example 1 only in that the prepared composite membrane is further aged through step 3.

[0048] Example 11 A non-woven composite membrane is different from Example 4 only in that the composite membrane is further aged after step 3.

[0049] Example 12 A non-woven composite membrane, which differs from Example 7 only in that it further undergoes step 3 to mature the prepared composite membrane.

[0050] Comparative Example 1 A non-woven composite membrane, the difference from Example 1 is that the non-woven layer has a gram weight of 35g / m 2. .

[0051] Comparative Example 2 A non-woven composite membrane, the difference from Example 1 is that the non-woven layer has a gram weight of 8g / m 2. .

[0052] Comparative Example 3 A non-woven composite membrane, the difference from Example 4 is that the non-woven layer has a gram weight of 35g / m 2. .

[0053] Performance tests were performed on the above embodiments.

[0054] Test items Friction coefficient Tensile strength, MPa Impressions Test standards Example 1 0.37 Vertical 45 / Horizontal 38 Paper texture, no obvious texture GB / T 1040.3 Example 2 0.35 Vertical 55 / Horizontal 42 Metallic luster, reflective barrier layer GB / T 1040.3 Example 3 0.42 Vertical 50 / Horizontal 43 Matte effect, PE / PP mixed color texture ASTM D2457 Example 4 0.48 Vertical 60 / Horizontal 47 Significant paper texture / three-dimensional cross texture TAPPI T498 Example 5 0.42 Vertical 58 / Horizontal 46 Matte surface ISO 534 Example 6 0.43 Vertical 65 / Horizontal 51 Twill effect GB / T 8808 Example 7 0.42 48 vertically / 35 horizontally Fine mesh structure, low gloss GB / T 5453 Example 8 0.55 Vertical 62 / Horizontal 45 High roughness, obvious friction resistance DIN 53375 Example 9 0.41 Vertical 55 / Horizontal 40 Smooth surface, no obvious texture ASTM D1003 Example 10 0.35 Vertical 47 / Horizontal 36 Improved surface flatness GB / T 2918 Example 11 0.58 Vertical 63 / Horizontal 49 Paper texture ISO 2231 Example 12 0.42 Vertical 50 / Horizontal 37 translucent ASTM E96 Comparative Example 1 0.45 Vertical 50 / Horizontal 40 Paper texture, with slight wrinkles GB / T 1040.3 Comparative Example 2 0.22 Vertical 28 / Horizontal 22 Thin, transparent, easy to disperse at the edge GB / T 1040.3 Comparative Example 3 0.67 Vertical 42 / Horizontal 35 Rough surface and poor local bonding GB / T 1040.3 The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A paper-textured non-woven composite film, characterized in that: It includes a surface layer, a first extrusion layer, a non-woven fabric layer, a second extrusion layer and a heat-sealing layer arranged in sequence; The surface layer is selected from one of OPP, PET, and NY; The preparation method of the non-woven fabric layer comprises the following steps: melting PE and / or PP and spinning them into a fiber web, and then hot-pressing and solidifying the fiber web to obtain a non-woven fabric roll film. The non-woven fabric has a gram weight of 10-30 g / m 2 ; The heat sealing layer is selected from CPP and / or PE film materials; The first extruded layer and the second extruded layer are PE layers extruded and laminated on the upper and lower sides of the non-woven fabric.

2. The paper-textured nonwoven composite film according to claim 1, characterized in that: A barrier layer is further provided between the second extrusion layer and the heat-sealing layer, and the barrier layer is glued to the adjacent layers using two-component polyurethane glue.

3. The paper-textured nonwoven composite film according to claim 1, characterized in that: The non-woven fabric layer is formed by melting and hot pressing PE / PP fibers to form a cross-network structure. The porosity of the non-woven fabric layer is 30-50%, and the pore connectivity is ≥80%.

4. The paper-textured nonwoven composite film according to claim 3, characterized in that: The non-woven fabric layer preparation step comprises: S01, melt blending PE and / or PP with nano-CaCO3; S02, the resin matrix melt-blended and mixed with nano-CaCO3 is cross-laid through a double die head to form a fiber web with a fiber angle; S03, processing the fiber web with the fiber angle by a three-roll calender unit.

5. The paper-textured nonwoven composite film according to claim 4, characterized in that: In S01: the weight percentage of nano-CaCO3 in the resin matrix is ​​0.5-2%; In S02, the fiber angle formed by the cross-laying of the two die heads is 90-150°; In S03, the roller temperatures of the three-roll calender unit are: upper roller 120°C; middle roller 145°C; lower roller 100°C, and the line pressure of the three-roll calender unit is 10 kg / cm.

6. The paper-textured nonwoven composite film according to claim 1, characterized in that: The PP fibers and PE fibers are arranged in a staggered manner, wherein the axial directions of the PP fibers and the axial directions of the PE fibers form an asymmetric angle distribution, forming an asymmetric cross network structure, wherein the angle between the axial directions of the PP fibers and the axial directions of the PE fibers is controlled in the range of 90°-150°.

7. A method for preparing the paper-textured non-woven composite membrane according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Place the surface layer substrate on the first unwinding unit of the extruder, and place the non-woven fabric layer substrate on the second unwinding unit of the extruder. The surface layer is connected to the non-woven fabric layer after the first extrusion layer is laminated by the rubber roller; Step 2: Place the heat seal layer substrate on the second unwinding unit of the extruder, and place the non-woven fabric layer substrate on the second unwinding unit of the extruder. The heat seal layer is connected to the non-woven fabric layer by the second extrusion layer thickness of the coating roller; Step 3: Curing the prepared non-woven composite membrane.

8. The method for preparing the paper-textured nonwoven composite film according to claim 7, wherein: In step 1, the die head temperature of the first unwinding unit of the extruder is 320-340°C, the die head compounding pressure is 2-5 bar, the unwinding tension is 4-5 kgf, the winding tension is 30-40 kgf, the die head temperature of the second unwinding unit of the extruder is 320-340°C, and the die head compounding pressure is 3-5 bar; In step 2, the die head temperature of the first unwinding unit of the extruder is 320-340°C, the die head compounding pressure is 2-5 bar, the unwinding tension is 4-5 kgf, the winding tension is 30-40 kgf, the die head temperature of the second unwinding unit of the extruder is 320-340°C, and the die head compounding pressure is 3-5 bar; In step 3, the non-woven composite membrane is aged at 40° C. for more than 24 hours.

9. The method for preparing the paper-textured nonwoven composite film according to claim 8, wherein: The extrusion pressure of the rubber roller on the first extrusion layer and / or the second extrusion layer is 1-3 bar.

10. The paper-textured nonwoven composite film according to claim 8, characterized in that: The glue is a two-component polyurethane glue, and the two-component polyurethane glue group includes a main agent, a curing agent and a solvent in a mass ratio of 10:3:15.

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