A bopp reinforced coating working solution and preparation method, reinforced coating, aluminized film

Abstract

This invention discloses a BOPP reinforcing coating working solution and its preparation method, as well as a reinforcing coating and an aluminized film. The raw materials for preparing the BOPP reinforcing coating working solution, by weight, include: 100 parts of waterborne polyurethane main agent, 0.5-3 parts of silica sol, 0.4-2 parts of wetting agent, 5-30 parts of isopropanol, 3-8 parts of curing agent, 0.6-2 parts of coupling agent, 1-5 parts of low-temperature heat-sealing modifier, and 80-200 parts of deionized water. The BOPP reinforcing coating working solution is applied to the surface of a BOPP substrate using an online coating process to obtain the BOPP reinforcing coating. The BOPP reinforcing coating is then subjected to vacuum aluminizing treatment to obtain an aluminized BOPP film. The reinforcing coating prepared by the BOPP reinforcing coating working solution of this invention has the characteristics of being environmentally friendly, having good aluminizing adhesion, excellent high and low temperature heat-sealing performance, outstanding barrier properties with long-term stability, and strong environmental stability.

Description

Technical Field

[0001] This invention relates to the field of packaging material coating technology, and in particular to a BOPP reinforcing coating working solution and its preparation method, reinforcing coating, and aluminized film. Background Technology

[0002] BOPP film is widely used in the packaging industry due to its advantages such as light weight, transparency, high mechanical strength, and low cost. Metallization, a common modification process, can endow BOPP film with barrier and light-blocking properties. However, traditional metallized BOPP film suffers from problems such as insufficient bonding strength between the metallized layer and the BOPP substrate, poor heat-sealing performance (especially insufficient heat-sealing strength at low temperatures, easily leading to packaging seal failure; the normal heat-sealing temperature is 120℃), and poor environmental stability (such as insufficient resistance to boiling water and chemical reagents, and degradation of barrier performance after long-term storage), which limit its application in high-requirement packaging scenarios.

[0003] Existing coating technologies for improving the performance of BOPP metallized films have several drawbacks: solvent-based systems are environmentally unfriendly and pose safety hazards; while water-based coatings are environmentally friendly, they perform poorly in balancing metallization adhesion and heat-sealing strength, with particularly weak low-temperature heat-sealing performance, making them difficult to adapt to low-temperature processing; some formulations fail to meet the barrier properties required for high-end packaging, and their barrier properties significantly degrade after long-term storage; furthermore, some formulations have poor compatibility with additives, resulting in insufficient coating uniformity and affecting the stability of subsequent metallization processes. Therefore, developing an environmentally friendly, metallization-adhesive-resistant, low-temperature heat-sealing, barrier-resistant, long-lasting, and environmentally stable online metallization-enhanced coating for BOPP is of significant practical importance. Summary of the Invention

[0004] The purpose of this invention is to provide a BOPP reinforced coating working solution and preparation method, reinforced coating, and aluminized film. It adopts an aqueous system, which is environmentally friendly and safe. The resulting BOPP aluminized film has good fastness, high low-temperature heat-sealing strength, water resistance, chemical resistance, and excellent and long-term stable barrier properties. Moreover, the preparation method is simple and easy to industrialize.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a BOPP reinforced coating working fluid, wherein the raw materials for preparing the BOPP reinforced coating working fluid, by weight, include: 100 parts of waterborne polyurethane main agent, 0.5-3 parts of silica sol, 0.4-2 parts of wetting agent, 5-30 parts of isopropanol, 3-8 parts of curing agent, 0.6-2 parts of coupling agent, 1-5 parts of low-temperature heat-sealing modifier, and 80-200 parts of deionized water.

[0007] In some possible embodiments, the waterborne polyurethane main agent is an aliphatic waterborne polyurethane dispersion with a solid content of 30-40%; the aliphatic waterborne polyurethane dispersion has good film-forming properties, flexibility and adhesion to BOPP substrate, which ensures the basic performance of the coating.

[0008] In some possible implementations, the silica sol is a neutral silica sol with a D50 particle size of 10-20 nm; the neutral silica sol can enhance the hardness, wear resistance and barrier properties of the coating, while having good compatibility with waterborne polyurethane main agent, avoiding problems such as coating delamination and precipitation.

[0009] In some possible embodiments, the wetting agent is a nonionic wetting agent, including polyoxyethylene alkylphenol ether, polyoxyethylene lauryl ether and polyoxyethylene octylphenol ether, used to reduce the surface tension of the coating, improve the wetting and spreading performance of the coating on the BOPP substrate, avoid defects such as pinholes and craters, and improve the uniformity of the coating.

[0010] In some possible implementations, the curing agent is an aqueous isocyanate curing agent, which can undergo a crosslinking reaction with the hydroxyl groups in the aqueous polyurethane main agent to form a three-dimensional network structure, significantly improving the heat-sealing strength, water resistance, and chemical resistance of the coating.

[0011] The coupling agent is γ-glycidyl etheroxypropyltrimethoxysilane, the alkoxy group at one end of which can be hydrolyzed to generate silanol groups. The silanol groups react with the hydroxyl groups on the surface of the silica sol and the BOPP substrate. The epoxy group at the other end can crosslink with the waterborne polyurethane main agent and the curing agent, thereby enhancing the bonding force between the components of the coating and the adhesion between the coating and the BOPP substrate, and further improving the adhesion of the aluminum-coated film.

[0012] In some possible embodiments, the low-temperature heat-sealing modifier is composed of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer in a weight ratio of 1:2~3. The polyethylene glycol monomethyl ether acrylate can reduce the heat-sealing initiation temperature of the coating and improve molecular fluidity at low temperatures. The ethylene-vinyl acetate copolymer has excellent low-temperature flexibility and heat-sealing compatibility. The two work synergistically to enable the coating to maintain high heat-sealing strength in the low-temperature range of 80~100℃ without affecting the high-temperature resistance and barrier properties of the coating.

[0013] Secondly, the present invention provides a BOPP reinforcing coating, which is based on the BOPP reinforcing coating working liquid described in the first aspect. The BOPP reinforcing coating working liquid is applied to the surface of a BOPP substrate through an online coating process, with the coating amount controlled at 1.5-2.5 g / m², and dried and cured at 100-120°C for 3-5 seconds to obtain the BOPP reinforcing coating.

[0014] Thirdly, the present invention also provides a method for preparing the BOPP reinforced coating working fluid described in the first and second aspects, the preparation method comprising the following steps:

[0015] Prepare the raw materials according to the weight proportions, mix the polyethylene glycol monomethyl ether acrylate with the ethylene-vinyl acetate copolymer, stir at 60~70℃ for 30~40min, cool to room temperature, and obtain the low temperature heat-sealing modifier.

[0016] Add the deionized water to the reaction vessel, turn on the stirring device, and control the speed at 300-500 r / min. Then add the isopropanol and the low-temperature heat-sealing modifier, and stir for 10-15 min to make the isopropanol and the low-temperature heat-sealing modifier evenly dispersed in the water.

[0017] While stirring, slowly add the waterborne polyurethane main agent and stir for 15-20 minutes until a uniform dispersion is formed; then add the silica sol and wetting agent in sequence, keeping the stirring speed constant, and stir for 20-30 minutes.

[0018] Adjust the stirring speed to 600-800 r / min, slowly add the coupling agent, stir for 15-20 min to allow the coupling agent to hydrolyze and react initially with the active groups in the system; then add the curing agent and continue stirring for 20-30 min to obtain a stable coating working solution.

[0019] The stabilizing coating working solution is aged at 25-30℃ for 30-60 minutes to eliminate air bubbles in the system, thereby obtaining the BOPP reinforced coating working solution and ensuring the stability and coating effect of the coating working solution.

[0020] Fourthly, the present invention also provides a BOPP aluminized film, which is prepared based on the BOPP reinforcing coating described in the second aspect, and the BOPP reinforcing coating is subjected to vacuum aluminizing treatment to obtain the BOPP aluminized film.

[0021] In some possible implementations, the BOPP aluminized film can be widely used in high-barrier packaging for food, pharmaceuticals, daily chemicals, electronics and other fields that require low-temperature processing and long-term storage.

[0022] The present invention provides a BOPP reinforcing coating working fluid and preparation method, as well as a reinforcing coating and an aluminized film, which have the following advantages:

[0023] 1. Excellent overall performance, with advantages in low-temperature heat sealing. A low-temperature heat-sealing modifier is introduced, working synergistically with waterborne polyurethane main agent, silica sol, coupling agent, and other components. The resulting BOPP reinforced coating not only exhibits good aluminized film adhesion (no peeling off with 3M tape), excellent water resistance (no peeling off of the aluminum layer after immersion in boiling water at 100℃ for 1 hour), strong resistance to chemical reagents (resistant to erosion by 3% acetic acid, saturated saline solution, etc.), but also outstanding barrier properties (oxygen barrier rate 0.5-0.8cm). 3 / (m 2 • 24h • 0.1MPa), water resistance rate 0.2-0.3g / (m 2 It features 24h) and also has excellent low-temperature heat-sealing performance. Under low-temperature heat-sealing conditions of 80~100℃, the heat-sealing strength can still reach 2.8~3.5N / 15mm, which meets the requirements of low-temperature processing technology and avoids the impact of high-temperature heat sealing on the contents of the packaging.

[0024] 2. Long-lasting and stable barrier performance: The components of the BOPP reinforced coating working fluid work together to form a dense and stable coating structure. After 6 months of storage at room temperature, the oxygen barrier rate and water barrier rate decrease by less than 5%, which is significantly better than existing coatings and can effectively extend the shelf life of the packaged contents.

[0025] 3. Environmental protection and safety: It adopts a water-based system with water as the main solvent and a small amount of isopropanol as a supplement. There is no volatilization of toxic and harmful solvents, which meets environmental protection requirements and reduces safety hazards in the production process.

[0026] 4. Good formulation compatibility: The low-temperature heat-sealing modifier has a high degree of matching with other components, with no stratification or precipitation. The prepared coating working solution has high stability and the coating process is smooth.

[0027] 5. Simple preparation process: It only adds a mixing step of low-temperature heat-sealing modifier to the existing process, without the need for complex equipment and harsh reaction conditions, resulting in high production efficiency and easy large-scale industrial production.

[0028] 6. Broader application prospects: The online coating and aluminizing process applicable to BOPP film can produce aluminized BOPP film that can be widely used in high-barrier packaging for food, pharmaceuticals, daily chemicals, electronics and other fields that require low-temperature processing and long-term storage, further expanding its market application prospects. Attached Figure Description

[0029] Figure 1 The flowchart illustrates the preparation method provided by this invention. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] The following performance tests were performed on the embodiments and comparative examples:

[0032] Aluminum coating adhesion: Using the 3M tape peeling method, the degree of aluminum layer peeling after peeling is divided into 1-5 levels (level 1 is the best, no peeling; level 5 is the worst, large area peeling).

[0033] Heat seal strength: Tested according to GB / T10004-2008 standard, under the conditions of heat seal temperature of 80℃, 100℃, and 120℃, pressure of 0.3MPa, and time of 1s;

[0034] Water resistance test: Immerse in boiling water at 100℃ for 1 hour and observe the integrity of the aluminum layer and whether it peels off;

[0035] Chemical resistance: The aluminum layer was immersed in 3% acetic acid, saturated saline solution, ethanol, propanol, and 3% hydrogen peroxide for 24 hours respectively, and the integrity of the aluminum layer and whether it peeled off were observed.

[0036] Oxygen barrier rate: According to GB / T19789-2005, the initial value and the value after 6 months of storage at room temperature were tested respectively;

[0037] Water resistance: Tested according to GB / T26253-2010, with initial values ​​and values ​​after 6 months of storage at room temperature.

[0038] Example 1

[0039] This embodiment provides a BOPP reinforced coating working solution. The raw materials for preparation, by weight, include: 100 parts of aliphatic waterborne polyurethane dispersion (solid content of 35%), 1 part of neutral silica sol (D50 particle size of 15nm), 0.8 parts of polyoxyethylene alkylphenol ether (nonionic wetting agent), 10 parts of isopropanol, 7 parts of waterborne isocyanate curing agent, 1.2 parts of γ-glycidyl etheroxypropyltrimethoxysilane (KH560), 3 parts of low-temperature heat-sealing modifier, and 160 parts of deionized water.

[0040] The low-temperature heat-sealing modifier is a mixture of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer in a weight ratio of 1:2.5.

[0041] Preparation method of BOPP reinforced coating working fluid, such as Figure 1 As shown, it includes the following steps:

[0042] Preparation of materials: Prepare the raw materials according to the weight proportions, mix polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer, stir at 65°C for 35 min, cool to room temperature to obtain low temperature heat-sealing modifier;

[0043] Premixing: Add the deionized water to the reaction vessel, turn on the stirring device, control the speed at 350 r / min, then add isopropanol and low-temperature heat-sealing modifier, and stir for 12 min.

[0044] Dispersed addition: While stirring, slowly add the waterborne polyurethane main agent and stir for 18 minutes. Then add the silica sol and wetting agent in sequence, keeping the stirring speed constant, and stir for 25 minutes.

[0045] Construction of crosslinking system: Adjust the stirring speed to 700 r / min, slowly add the coupling agent, stir for 18 min, then add the curing agent, and continue stirring for 25 min to obtain a stable coating working solution.

[0046] Curing: The stabilizing coating working solution is cured at 28°C for 45 minutes to obtain the BOPP reinforced coating working solution.

[0047] This embodiment provides a BOPP reinforcing coating. The BOPP reinforcing coating working liquid is applied to the surface of the BOPP substrate through an online coating process. The coating amount is controlled at 2.0 g / m², and the coating is dried and cured at 110°C for 4 seconds to obtain the BOPP reinforcing coating.

[0048] This embodiment provides a BOPP aluminum-coated film, wherein the BOPP reinforcing coating is subjected to vacuum aluminum plating treatment, and the aluminum layer thickness is 40nm, to obtain the BOPP aluminum-coated film.

[0049] The performance test results are as follows:

[0050]

[0051] Example 2

[0052] This embodiment provides a BOPP reinforced coating working solution. The raw materials for preparation include, by weight, 100 parts of aliphatic waterborne polyurethane dispersion (solid content of 30%), 1.5 parts of neutral silica sol (D50 particle size of 10nm), 1 part of polyoxyethylene lauryl ether (nonionic wetting agent), 15 parts of isopropanol, 5 parts of waterborne isocyanate curing agent, 1.2 parts of γ-glycidyl etheroxypropyltrimethoxysilane (KH560), 2 parts of low-temperature heat-sealing modifier, and 160 parts of deionized water.

[0053] The low-temperature heat-sealing modifier is a mixture of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer in a weight ratio of 1:2.

[0054] The preparation method of the BOPP reinforced coating working fluid includes the following steps:

[0055] Preparation of materials: Prepare the raw materials according to the weight proportions, mix polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer, stir at 60°C for 40 min, cool to room temperature to obtain low temperature heat-sealing modifier;

[0056] Premixing: Add the deionized water to the reaction vessel, turn on the stirring device, control the speed at 300 r / min, then add isopropanol and low-temperature heat-sealing modifier, and stir for 15 min.

[0057] Dispersed addition: While stirring, slowly add the waterborne polyurethane main agent and stir for 20 minutes. Then add the silica sol and wetting agent in sequence, keeping the stirring speed constant, and stir for 30 minutes.

[0058] Construction of crosslinking system: Adjust the stirring speed to 600 r / min, slowly add the coupling agent, stir for 20 min, then add the curing agent, and continue stirring for 30 min to obtain a stable coating working solution.

[0059] Curing: The stabilizing coating working solution is cured at 25°C for 60 minutes to obtain the BOPP reinforced coating working solution.

[0060] This embodiment provides a BOPP reinforcing coating. The BOPP reinforcing coating working liquid is applied to the surface of the BOPP substrate through an online coating process. The coating amount is controlled at 1.5g / m², and the coating is dried and cured at 100℃ for 5s to obtain the BOPP reinforcing coating.

[0061] This embodiment provides a BOPP aluminum-coated film, wherein the BOPP reinforcing coating is subjected to vacuum aluminum plating treatment, and the aluminum layer thickness is 35nm, to obtain the BOPP aluminum-coated film.

[0062] The performance test results are as follows:

[0063]

[0064] Example 3

[0065] This embodiment provides a BOPP reinforced coating working solution. The raw materials for preparation include, by weight, 100 parts of aliphatic waterborne polyurethane dispersion (solid content of 40%), 0.8 parts of neutral silica sol (D50 particle size of 20nm), 1 part of polyoxyethylene octylphenol ether (nonionic wetting agent), 12 parts of isopropanol, 6 parts of waterborne isocyanate curing agent, 1.4 parts of γ-glycidyl etheroxypropyltrimethoxysilane (KH560), 4 parts of low-temperature heat-sealing modifier, and 160 parts of deionized water.

[0066] The low-temperature heat-sealing modifier is a mixture of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer in a weight ratio of 1:3.

[0067] The preparation method of the BOPP reinforced coating working fluid includes the following steps:

[0068] Preparation of materials: Prepare the raw materials according to the weight proportions, mix polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer, stir at 70°C for 30 min, cool to room temperature to obtain low temperature heat-sealing modifier;

[0069] Premixing: Add the deionized water to the reaction vessel, turn on the stirring device, control the speed at 500 r / min, then add isopropanol and low-temperature heat-sealing modifier, and stir for 10 min.

[0070] Dispersed addition: While stirring, slowly add the waterborne polyurethane main agent and stir for 15 minutes. Then add the silica sol and wetting agent in sequence, keeping the stirring speed constant, and stir for 20 minutes.

[0071] Construction of crosslinking system: Adjust the stirring speed to 800 r / min, slowly add the coupling agent, stir for 15 min, then add the curing agent, and continue stirring for 20 min to obtain a stable coating working solution.

[0072] Curing: The stabilizing coating working solution is cured at 30°C for 30 minutes to obtain the BOPP reinforced coating working solution.

[0073] This embodiment provides a BOPP reinforcing coating. The BOPP reinforcing coating working liquid is applied to the surface of the BOPP substrate through an online coating process. The coating amount is controlled at 2.5g / m², and the coating is dried and cured at 120℃ for 3s to obtain the BOPP reinforcing coating.

[0074] This embodiment provides a BOPP aluminum-coated film, wherein the BOPP reinforcing coating is subjected to vacuum aluminum plating treatment, and the aluminum layer thickness is 45nm, to obtain the BOPP aluminum-coated film.

[0075] The performance test results are as follows:

[0076]

[0077] Comparative Example 1

[0078] The only difference between this comparative example and Example 1 is that 0 parts of γ-glycidyl etheroxypropyltrimethoxysilane (KH560) were used.

[0079] The performance test results are as follows:

[0080]

[0081] Comparative Example 2

[0082] The only difference between this comparative example and Example 1 is that there are 0 parts of low-temperature heat sealant.

[0083] The performance test results are as follows:

[0084]

[0085] Comparative Example 3

[0086] The only difference between this comparative example and Example 1 is the addition of 2 parts of water-based isocyanate curing agent.

[0087] The performance test results are as follows:

[0088]

[0089] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A BOPP reinforced coating working fluid, characterized in that, The raw materials for preparing the BOPP reinforced coating working fluid, by weight, include: 100 parts of waterborne polyurethane main agent, 0.5-3 parts of silica sol, 0.4-2 parts of wetting agent, 5-30 parts of isopropanol, 3-8 parts of curing agent, 0.6-2 parts of coupling agent, 1-5 parts of low-temperature heat-sealing modifier, and 80-200 parts of deionized water. The low-temperature heat-sealing modifier is composed of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer in a weight ratio of 1:2~3.

2. The BOPP reinforced coating working fluid according to claim 1, characterized in that, The waterborne polyurethane main agent is an aliphatic waterborne polyurethane dispersion with a solid content of 30-40%.

3. The BOPP reinforced coating working fluid according to claim 1, characterized in that, The silica sol is a neutral silica sol with a D50 particle size of 10-20 nm.

4. The BOPP reinforced coating working fluid according to claim 1, characterized in that, The wetting agent is a nonionic wetting agent, including one of polyoxyethylene octylphenol ether and polyoxyethylene lauryl ether.

5. The BOPP reinforced coating working fluid according to claim 1, characterized in that, The curing agent is a water-based isocyanate curing agent, which can undergo a cross-linking reaction with the hydroxyl groups in the water-based polyurethane main agent to form a three-dimensional network structure. The coupling agent is γ-glycidoxypropyltrimethoxysilane, the alkoxy group at one end of which can be hydrolyzed to generate silanol groups. The silanol groups react with the hydroxyl groups on the surface of the silica sol and BOPP substrate, while the epoxy groups at the other end can crosslink with the waterborne polyurethane main agent and curing agent.

6. A BOPP reinforced coating, based on the BOPP reinforced coating working fluid according to any one of claims 1-5, characterized in that, The BOPP reinforcing coating working liquid is applied to the surface of the BOPP substrate using an online coating process, with the coating amount controlled at 1.5-2.5 g / m², and then dried and cured at 100-120℃ for 3-5 seconds to obtain the BOPP reinforcing coating.

7. A method for preparing the BOPP reinforced coating working fluid according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: Prepare the raw materials according to the weight proportions, mix the polyethylene glycol monomethyl ether acrylate with the ethylene-vinyl acetate copolymer, stir at 60~70℃ for 30~40min, cool to room temperature, and obtain the low temperature heat-sealing modifier. Add the deionized water to the reaction vessel, turn on the stirring device, control the speed at 300-500 r / min, then add the isopropanol and low-temperature heat-sealing modifier, and stir for 10-15 min; While stirring, slowly add the waterborne polyurethane main agent and stir for 15-20 minutes. Then add the silica sol and wetting agent in sequence, keeping the stirring speed constant, and stir for 20-30 minutes. Adjust the stirring speed to 600-800 r / min, slowly add the coupling agent, stir for 15-20 min, then add the curing agent, and continue stirring for 20-30 min to obtain a stable coating working solution; The stabilizing coating working solution is aged at 25-30℃ for 30-60 minutes to eliminate air bubbles in the system, thus obtaining the BOPP reinforced coating working solution.

8. A BOPP aluminized film, prepared based on the BOPP reinforced coating according to claim 6, characterized in that, The BOPP reinforced coating is subjected to vacuum aluminizing treatment to obtain the BOPP aluminized film.

9. The BOPP aluminized film according to claim 8, characterized in that, The BOPP aluminized film can be widely used in high-barrier packaging for food, pharmaceuticals, daily chemicals, and electronics industries that require low-temperature processing and long-term storage.

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