Special PE film compounded with pearl wool and preparation method thereof

Abstract

The invention discloses a special PE film compounded with pearl wool and a preparation method of the special PE film. The special PE film is characterized by comprising a pearl wool base material layer, a PE film layer and a cross-linking functional layer, wherein the cross-linking functional layer is positioned between the pearl wool base material layer and the PE film layer, realizes firm combination between the pearl wool base material layer and the PE film layer and can effectively absorb and disperse stress to avoid stress concentration when being stressed; the cross-linking functional layer is formed by carrying out cross-linking reaction on a composition containing waterborne polyurethane, modified graphene and a carbodiimide cross-linking agent. According to the invention, the cross-linked functional layer reacts with carboxyl of waterborne polyurethane through carbodiimide to form a stable N-acyl urea three-dimensional network structure, so that firm chemical bonding between the pearl wool and the PE film is realized, the interface bonding force is enhanced, the peel strength can reach 3-5 N / cm, and the problems of easy layering and bubbles in the use process are effectively solved.

Description

Technical Field

[0001] This invention relates to composite PE film, specifically a special PE film composited with pearl cotton and its preparation method. Background Technology

[0002] EPE (Expanded Polyethylene) is a common cushioning packaging material, characterized by its lightweight, flexibility, and impact resistance, and is widely used in the packaging of electronic products, furniture, and fragile items. However, EPE's smooth surface and low polarity make it prone to problems such as weak adhesion and low peel strength when laminated with polyethylene (PE) film, affecting the overall performance of the packaging material. Traditional lamination methods suffer from insufficient heat resistance and weak interfacial bonding, and the resulting composite also exhibits low tensile strength and poor puncture and tear resistance. Therefore, this paper proposes a special PE film for lamination with EPE and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to solve the above problems by proposing a special PE film for composite with pearl cotton and its preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a special PE film for composite with pearl cotton, characterized in that it includes a pearl cotton substrate layer, a PE film layer, and a cross-linking functional layer located between the two to achieve a firm bond between the pearl cotton substrate layer and the PE film layer and to effectively absorb and disperse stress and avoid stress concentration when subjected to stress; the cross-linking functional layer is formed by a cross-linking reaction of a composition comprising waterborne polyurethane, modified graphene and carbodiimide cross-linking agent.

[0005] More preferably, the composition in the crosslinked functional layer comprises, by weight: 100 parts of waterborne polyurethane, 3-8 parts of modified graphene, and 3-6 parts of carbodiimide crosslinking agent.

[0006] More preferably, the modified graphene is graphene nanosheets modified with silane coupling agents or surfactants, with a specific surface area greater than 300 m² / g.

[0007] More preferably, the crosslinking functional layer achieves three-dimensional network crosslinking through an N-acylurea structure generated by the reaction of a carbodiimide crosslinking agent with the carboxyl groups on the waterborne polyurethane molecular chain.

[0008] More preferably, the density of the pearl cotton substrate layer is 15-30 kg / m³, and the thickness is 1-10 mm.

[0009] More preferably, the thickness of the PE film layer is 20-100 μm, and it is made of low-density polyethylene or linear low-density polyethylene material.

[0010] More preferably, the thickness of the cross-linked functional layer is 0.5-5 μm.

[0011] A method for preparing a special PE film composite with pearl cotton, characterized by comprising the following steps: a. Prepare a reactive slurry by mixing modified graphene, aqueous polyurethane dispersion and carbodiimide crosslinking agent; b. Apply the reactive slurry to the surface of the pearl cotton substrate layer and preheat it at 90-110℃ for 30-60 seconds to remove moisture and initiate preliminary cross-linking to form a pre-cross-linked layer; c. The PE film layer and the pearl cotton substrate layer with the pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at a temperature of 110-130℃ and a pressure of 0.5-1.0MPa to ensure that the crosslinking reaction is fully carried out; d. After cooling and winding, cure at room temperature for 24-72 hours to obtain the composite PE film.

[0012] More preferably, in step a, the reactive slurry is used within 4-8 hours after preparation.

[0013] More preferably, in step b, micro-gravure roller coating is used, and the wet weight of the coating is 10-20 g / m²; in step c, the roller speed of the hot roller composite unit is 5-20 m / min.

[0014] The beneficial effects of this invention are as follows: The cross-linked functional layer forms a stable N-acylurea three-dimensional network structure through the reaction of carbodiimide and carboxyl groups of waterborne polyurethane, which enables a strong chemical bond between the pearl cotton substrate layer and the PE film, enhances the interfacial bonding force, and the peel strength can reach 3-5 N / cm, effectively solving the problems of easy delamination and bubbles during use. By using modified graphene nanosheets as reinforcements, which are uniformly dispersed in the cross-linked network, their huge specific surface area and two-dimensional sheet structure can effectively transfer and disperse stress, and hinder the slippage of molecular chains, thereby enhancing the tensile strength, puncture resistance and tear resistance of the composite film. The highly cross-linked three-dimensional network structure restricts the movement of polymer molecular chains at high temperatures, effectively improving heat resistance and avoiding the delamination problem caused by the softening of traditional adhesives during high-temperature storage or transportation in summer. By incorporating graphene nanosheets, a labyrinthine physical barrier pathway is formed within the polymer matrix, which can also construct a thermally conductive network, thereby improving the barrier performance of the composite PE film against oxygen and water vapor to a certain extent. Detailed Implementation

[0015] Below, we will further explain the special PE film composited with pearl cotton and its preparation method according to the present invention.

[0016] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationship and movement of the components in a specific posture as shown. If the specific posture changes, the directional indication will also change accordingly.

[0017] A special PE film for composite with pearl cotton, characterized by comprising a pearl cotton substrate layer, a PE film layer, and a cross-linking functional layer located between the two, which enables a firm bond between the pearl cotton substrate layer and the PE film layer and can effectively absorb and disperse stress to avoid stress concentration when subjected to stress; the cross-linking functional layer is formed by a cross-linking reaction of a composition comprising waterborne polyurethane, modified graphene and carbide diimide cross-linking agent. The composition in the crosslinked functional layer, by weight, comprises: 100 parts of waterborne polyurethane, 3-8 parts of modified graphene, and 3-6 parts of carbodiimide crosslinking agent. The modified graphene is graphene nanosheets modified with silane coupling agents or surfactants, with a specific surface area greater than 300 m² / g. The cross-linking functional layer generates stable N-acylurea covalent bonds through the reaction of carbodiimide and the carboxyl groups of waterborne polyurethane, forming a stable N-acylurea three-dimensional network structure. This fixes the pearl cotton substrate layer and the PE film on a strong network, thereby eliminating delamination caused by insufficient adhesion, achieving a strong chemical bond between the pearl cotton substrate layer and the PE film, and enhancing the interfacial bonding force. Meanwhile, this application includes a preheating step of 90-110°C immediately after the slurry is applied. This preheating step can quickly and thoroughly disperse and remove water, eliminating the source of air bubbles before entering the heat bonding stage, thus fundamentally solving the problem of air bubbles caused by the vaporization of residual moisture. By employing modified graphene nanosheets as reinforcements, uniformly dispersed within a cross-linked network, their enormous specific surface area and two-dimensional layered structure allow for the transmission of force through polymer molecular chains when subjected to external forces. When the force reaches the molecular chains tightly bound to the graphene, due to graphene's extremely high modulus, the graphene nanosheet rapidly disperses and redistributes the received stress within its entire two-dimensional plane, effectively transferring and dispersing stress. Meanwhile, the graphene nanosheets are uniformly dispersed in the matrix. When the molecular chains attempt to slide under external force, their movement path is blocked and restricted by these graphene nanosheets, thereby hindering the slippage of the molecular chains and enhancing the tensile strength, puncture resistance and tear resistance of the composite film. By incorporating graphene nanosheets, when a large number of graphene nanosheets are uniformly dispersed in the polymer matrix, these nanosheets act as countless randomly arranged and intersecting nanowalls. When gas molecules encounter these nanosheets during diffusion, they are forced to change direction and bypass them. This creates an extremely tortuous and complex channel through the numerous graphene nanosheets, forming a labyrinthine physical barrier path within the polymer matrix. This significantly extends the effective diffusion path of gas molecules, leading to a sharp decrease in the permeability of oxygen and water vapor. Consequently, this enhances the barrier performance of the composite PE film against oxygen and water vapor, providing better protection when packaging contents. When graphene nanosheets are uniformly dispersed in a polymer and their content reaches a certain threshold, these isolated sheets will approach, contact, and even overlap each other, forming a continuous three-dimensional thermally conductive network throughout the composite material. When heat is transferred to the edge of one of the graphene nanosheets, it will be transferred to the adjacent graphene nanosheet through point contact or surface contact, continuing to be rapidly conducted, and finally transferred to the entire material or dissipated into the environment. This efficient thermal conduction mechanism greatly improves the overall thermal conductivity of the composite material, enhancing the material's dimensional stability and heat resistance. The introduction of graphene can also endow the material with weak thermal conductivity or antistatic properties. The cross-linked functional layer achieves three-dimensional network cross-linking through the N-acylurea structure generated by the reaction of carbodiimide cross-linking agent with carboxyl groups on the waterborne polyurethane molecular chain; the highly cross-linked three-dimensional network structure restricts the movement of polymer molecular chains at high temperatures, effectively improving heat resistance and avoiding the delamination problem caused by the softening of traditional adhesives during high-temperature storage or transportation in summer. The density of the pearl cotton substrate layer is 15-30 kg / m, and the thickness is 1-10 mm; The thickness of the PE film layer is 20-100μm, and it is made of low-density polyethylene or linear low-density polyethylene. The thickness of the cross-linked functional layer is 0.5-5 μm.

[0018] Example 1: Preparation of cross-linked functional layer composition By weight, take 100 parts of waterborne polyurethane, 5 parts of modified graphene (modified with silane coupling agent, specific surface area 350 m² / g), and 4 parts of carbodiimide crosslinking agent. First, the modified graphene is dispersed in deionized water and ultrasonically treated for 30 minutes. Then, it is mixed with an aqueous polyurethane dispersion and finally, a carbodiimide crosslinking agent is added. The mixture is mechanically stirred for 1 hour to obtain a reactive slurry. This slurry should be used within 6 hours after preparation.

[0019] Example 2: Preparation of a special PE film a. Prepare a reactive slurry using the composition of Example 1; b. After cleaning the surface of the pearl cotton substrate layer (density 20kg / m³, thickness 5mm), apply a reactive slurry using a micro-gravure roller, with a wet weight of 15g / m²; then preheat at 100℃ for 40 seconds to form a pre-crosslinked layer. c. The PE film layer (low-density polyethylene, 50μm thick) and the pearl cotton substrate layer with pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at 120℃ and 0.8MPa pressure, with the roller speed set to 10m / min. d. After cooling and winding, the composite special PE film is obtained after curing at room temperature for 48 hours.

[0020] By combining preheating and hot pressing steps, moisture is removed and cross-linking reaction is promoted, shortening the time required for complete curing.

[0021] Example 3: Preparation of high graphene content composite film By weight, take 100 parts of waterborne polyurethane, 8 parts of modified graphene (modified with silane coupling agent, specific surface area 350 m² / g), and 6 parts of carbodiimide crosslinking agent. First, the modified graphene is dispersed in deionized water and ultrasonically treated for 30 minutes. Then, it is mixed with an aqueous polyurethane dispersion and finally, a carbodiimide crosslinking agent is added and mechanically stirred for 1 hour to obtain a reactive slurry. This slurry should be used within 8 hours after preparation. Preparation of special PE film a. Prepare the reactive slurry according to the above proportions; b. After cleaning the surface of the pearl cotton substrate layer (density 25kg / m³, thickness 8mm), apply a reactive slurry using a micro-gravure roller, with a wet weight of 18g / m²; then preheat at 105℃ for 50 seconds to form a pre-crosslinked layer. c. The PE film layer (low-density polyethylene, 80μm thick) and the pearl cotton substrate layer with pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at 125℃ and 0.9MPa pressure, with the roller speed set to 8m / min. d. After cooling and winding, the composite special PE film is obtained after curing at room temperature for 60 hours.

[0022] Example 4: Preparation of a low-content graphene rapid curing composite film By weight, take 100 parts of waterborne polyurethane, 3 parts of modified graphene (modified with silane coupling agent, specific surface area 320 m² / g), and 3 parts of carbodiimide crosslinking agent. First, the modified graphene is dispersed in deionized water and ultrasonically treated for 30 minutes. Then, it is mixed with an aqueous polyurethane dispersion and finally, a carbodiimide crosslinking agent is added and mechanically stirred for 1 hour to obtain a reactive slurry. This slurry should be used within 4 hours after preparation. Preparation of special PE film a. Prepare the reactive slurry according to the above proportions; b. After cleaning the surface of the pearl cotton substrate layer (density 18 kg / m³, thickness 3 mm), apply a reactive slurry using a micro-gravure roller, with a wet weight of 12 g / m²; then preheat at 95°C for 60 seconds to form a pre-crosslinked layer. c. The PE film layer (low-density polyethylene, 30μm thick) and the pearl cotton substrate layer with pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at 115℃ and 0.6MPa pressure, with the roller speed set to 15m / min. d. After cooling and winding, the composite special PE film is obtained after curing at room temperature for 24 hours.

[0023] Example 5: Preparation of ultrathin functional layer composite film By weight, take 100 parts of waterborne polyurethane, 5 parts of modified graphene (modified with silane coupling agent, specific surface area 400 m² / g), and 4 parts of carbodiimide crosslinking agent. First, the modified graphene is dispersed in deionized water and ultrasonically treated for 30 minutes. Then, it is mixed with an aqueous polyurethane dispersion and finally, a carbodiimide crosslinking agent is added. The mixture is mechanically stirred for 1 hour to obtain a reactive slurry. This slurry should be used within 6 hours after preparation. Preparation of special PE film a. Prepare the reactive slurry according to the above proportions; b. After cleaning the surface of the pearl cotton substrate layer (density 22kg / m³, thickness 5mm), apply a reactive slurry using a micro-gravure roller, with a wet weight of 8g / m², and a target dry film thickness of approximately 0.8μm; then preheat at 100℃ for 35 seconds to form a pre-crosslinked layer. c. The PE film layer (low-density polyethylene, 40μm thick) and the pearl cotton substrate layer with pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at 120℃ and 0.7MPa pressure, with the roller speed set to 12m / min. d. After cooling and winding, the composite special PE film is obtained after curing at room temperature for 36 hours.

[0024] Example 6: Preparation of composite films with emphasis on thermal conductivity By weight, take 100 parts of waterborne polyurethane, 7 parts of modified graphene (modified with silane coupling agent, specific surface area 350 m² / g), and 5 parts of carbodiimide crosslinking agent. First, the modified graphene is dispersed in deionized water and ultrasonically treated for 30 minutes. Then, it is mixed with an aqueous polyurethane dispersion and finally, a carbodiimide crosslinking agent is added and mechanically stirred for 1 hour to obtain a reactive slurry. This slurry should be used within 4 hours after preparation. Preparation of special PE film a. Prepare the reactive slurry according to the above proportions; b. After cleaning the surface of the pearl cotton substrate layer (density 20kg / m³, thickness 10mm), apply a reactive slurry using a micro-gravure roller with a wet weight of 20g / m², and then preheat at 110℃ for 45 seconds to form a pre-crosslinked layer. c. The PE film layer (low-density polyethylene, 100μm thick) and the pearl cotton substrate layer with pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at 130℃ and 1.0MPa pressure, with the roller speed set to 10m / min. d. After cooling and winding, the composite special PE film is obtained after curing at room temperature for 48 hours.

[0025] The scope of protection of this invention is not limited to the above embodiments and their variations. Conventional modifications and substitutions made by those skilled in the art based on the content of these embodiments are all within the scope of protection of this invention.

Claims

1. A special PE film for composite with pearl cotton, characterized in that: It includes a pearl cotton substrate layer, a PE film layer, and a cross-linked functional layer located between the two to achieve a firm bond between the pearl cotton substrate layer and the PE film layer and to effectively absorb and disperse stress when subjected to stress, thereby avoiding stress concentration; the cross-linked functional layer is formed by a cross-linking reaction of a composition comprising waterborne polyurethane, modified graphene and carbodiimide cross-linking agent.

2. The special PE film for composite with pearl cotton according to claim 1, characterized in that: The composition in the crosslinked functional layer comprises, by weight: 100 parts of waterborne polyurethane, 3-8 parts of modified graphene, and 3-6 parts of carbodiimide crosslinking agent.

3. A special PE film for composite with pearl cotton according to claim 1 or 2, characterized in that: The modified graphene is graphene nanosheets modified with silane coupling agents or surfactants, with a specific surface area greater than 300 m² / g.

4. The special PE film for composite with pearl cotton according to claim 1, characterized in that: The cross-linked functional layer achieves three-dimensional network cross-linking through the N-acylurea structure generated by the reaction of carbodiimide cross-linking agent with carboxyl groups on the waterborne polyurethane molecular chain.

5. A special PE film for composite with pearl cotton according to claim 1, characterized in that: The density of the pearl cotton substrate layer is 15-30 kg / m³, and the thickness is 1-10 mm.

6. A special PE film for composite with pearl cotton according to claim 1, characterized in that: The thickness of the PE film layer is 20-100 μm, and it is made of low-density polyethylene or linear low-density polyethylene.

7. A special PE film for composite with pearl cotton according to claim 4, characterized in that: The thickness of the cross-linked functional layer is 0.5-5 μm.

8. A method for preparing a special PE film composite with pearl cotton according to any one of claims 1-7, characterized in that: Includes the following steps: a. Prepare a reactive slurry by mixing modified graphene, aqueous polyurethane dispersion and carbodiimide crosslinking agent; b. Apply the reactive slurry to the surface of the pearl cotton substrate layer and preheat it at 90-110℃ for 30-60 seconds to remove moisture and initiate preliminary cross-linking to form a pre-cross-linked layer; c. The PE film layer and the pearl cotton substrate layer with the pre-crosslinked layer are passed together through the hot roller composite unit and hot-pressed at a temperature of 110-130℃ and a pressure of 0.5-1.0MPa to ensure that the crosslinking reaction is fully carried out; d. After cooling and winding, cure at room temperature for 24-72 hours to obtain the composite PE film.

9. The method for preparing a special PE film composite with pearl cotton according to claim 8, characterized in that: In step a), the reactive slurry is used within 4-8 hours after preparation.

10. A method for preparing a special PE film composite with pearl cotton according to claim 8, characterized in that: In step b), microgravure roller coating is used, and the wet weight of the coating is 10-20 g / m²; in step c), the roller speed of the hot roller composite unit is 5-20 m / min.