BOPP (Biaxially-oriented Polypropylene) reinforced coating working solution, preparation method, reinforced coating and aluminum laminated film

Abstract

The invention discloses a BOPP enhanced coating working solution and a preparation method thereof, an enhanced coating and an aluminum laminated film, the BOPP enhanced coating working solution is prepared from the following raw materials in parts by weight: 100 parts of a waterborne polyurethane main agent, 0.5-3 parts of silica sol, 0.4-2 parts of a wetting agent, 5-30 parts of isopropanol, 3-8 parts of a curing agent, 0.6-2 parts of a coupling agent, 1-5 parts of a low-temperature heat-sealing modifier and 80-200 parts of deionized water. And coating the BOPP reinforced coating working solution on the surface of a BOPP base material through an online coating process to obtain the BOPP reinforced coating. And carrying out vacuum aluminizing treatment on the BOPP reinforced coating to obtain the BOPP aluminized film. A reinforced coating prepared from the BOPP reinforced coating working solution has the characteristics of environmental protection, good aluminizing fastness, excellent high-low temperature heat sealing performance, prominent barrier performance, long-acting stability and strong environment-resistant stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coating of packaging materials, in particular to a BOPP reinforced coating working solution and a preparation method thereof, a reinforced coating and an aluminum plated film. BACKGROUND

[0002] BOPP film is widely used in the packaging industry due to its light weight, transparency, high mechanical strength, low cost and other advantages. As a common modification method, aluminum plating process can endow BOPP film with barrier properties, light shielding properties and other functions. However, the traditional BOPP aluminum plated film has problems such as insufficient adhesion between the aluminum plated layer and the BOPP substrate, poor heat sealing performance (especially insufficient heat sealing strength at low temperature, which can easily lead to packaging sealing failure, and the normal heat sealing temperature is 120℃), poor environmental stability (such as insufficient resistance to boiling water and chemical reagents, and the barrier performance decays after long-term storage), which limits its application in high requirement packaging scenarios.

[0003] In the prior art, the coating coating scheme for improving the performance of BOPP aluminum plated film has many defects: the solvent type system has poor environmental protection and safety hazards; the water-based coating has good environmental protection, but performs poorly in the balance between aluminum plating adhesion and heat sealing strength, especially in low temperature heat sealing performance, which is difficult to adapt to low temperature processing technology; the barrier performance of some formulations cannot meet the high-end packaging requirements, and the barrier performance decays significantly after long-term storage; in addition, the compatibility of some additives is poor, which leads to insufficient coating uniformity and affects the stability of the subsequent aluminum plating process. Therefore, it is of great practical significance to develop a BOPP online coating aluminum plated reinforced coating that is environmentally friendly, has good aluminum plating adhesion, excellent low temperature heat sealing performance, outstanding and long-term stable barrier performance, and strong environmental stability. SUMMARY

[0004] The purpose of the present application is to provide a BOPP reinforced coating working solution and a preparation method thereof, a reinforced coating and an aluminum plated film, which adopts a water-based system, is environmentally friendly and safe, has good adhesion of the obtained BOPP aluminum plated film, high low temperature heat sealing strength, resistance to boiling water and chemical reagents, excellent and long-term stable barrier performance, and a simple preparation method process, which is easy to industrialize.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: In a first aspect, the present application provides a BOPP reinforced coating working solution, the preparation raw materials of the BOPP reinforced coating working solution by weight fraction, including: water-based polyurethane main agent 100 parts, silica sol 0.5-3 parts, wetting agent 0.4-2 parts, isopropyl alcohol 5-30 parts, curing agent 3-8 parts, coupling agent 0.6-2 parts, low temperature heat sealing modifier 1-5 parts, deionized water 80-200 parts.

[0006] In some possible implementation manners, the aqueous polyurethane main agent is an aliphatic aqueous polyurethane dispersion with a solid content of 30-40%; the aliphatic aqueous polyurethane dispersion has good film-forming property, flexibility and adhesion to the BOPP substrate, and provides guarantee for the basic performance of the coating.

[0007] In some possible implementation manners, 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 property of the coating, and has good compatibility with the aqueous polyurethane main agent, thereby avoiding problems such as delamination and precipitation of the coating.

[0008] In some possible implementation manners, the wetting agent is a non-ionic wetting agent, including polyoxyethylene alkyl phenol ether, polyoxyethylene lauryl ether and polyoxyethylene octyl phenol ether, which is 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 shrinkage holes and pinholes, and improve the uniformity of the coating.

[0009] In some possible implementation manners, the curing agent is an aqueous isocyanate curing agent, which can cross-link with the hydroxyl groups in the aqueous polyurethane main agent to form a three-dimensional network structure, thereby significantly improving the heat sealing strength, boiling water resistance and chemical reagent resistance of the coating.

[0010] The coupling agent is γ-glycidoxypropyltrimethoxysilane, the alkoxy group at one end of which can be hydrolyzed to form a silicon hydroxyl group, the silicon hydroxyl group reacts with the hydroxyl groups on the surface of the silica sol and the BOPP substrate, and the epoxy group at the other end can cross-link with the aqueous polyurethane main agent and the curing agent, thereby enhancing the binding force between the components of the coating and the adhesion between the coating and the BOPP substrate, and further improving the aluminum foil adhesion.

[0011] In some possible implementation manners, the low-temperature heat sealing modifier is a mixture of polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer at a weight ratio of 1:2-3; the polyethylene glycol monomethyl ether acrylate can reduce the heat sealing starting temperature of the coating and improve the molecular flowability at low temperature; the ethylene-vinyl acetate copolymer has excellent low-temperature flexibility and heat sealing compatibility, and the two components synergistically act to enable the coating to still have a relatively high heat sealing strength in the low-temperature range of 80-100℃, and not to affect the high-temperature resistance and barrier property of the coating.

[0012] In a second aspect, the present application provides a BOPP reinforced coating, which is prepared by coating the BOPP reinforced coating working solution in the first aspect on the surface of a BOPP substrate by an online coating process, the coating amount is controlled to be 1.5-2.5 g / m2, and the BOPP reinforced coating is obtained by drying and curing at 100-120℃ for 3-5 s.

[0013] In a third aspect, the present application further provides a preparation method of the BOPP reinforced coating working solution according to the first and second aspects, and the preparation method comprises the following steps: Prepare the raw materials by weight fraction, mix the polyethylene glycol monomethyl ether acrylate and the ethylene-vinyl acetate copolymer, stir at 60-70°C for 30-40 min, and cool to room temperature to obtain the low-temperature heat-sealing modifier; Add the deionized water into the reaction container, start the stirring device, control the rotating speed at 300-500 r / min, then add the isopropyl alcohol and the low-temperature heat-sealing modifier, and stir for 10-15 min to uniformly disperse the isopropyl alcohol and the low-temperature heat-sealing modifier in the water; Under the stirring state, slowly add the water-based polyurethane main agent, stir for 15-20 min until a uniform dispersion is formed in the system; then sequentially add the silica sol and the wetting agent, keep the stirring speed unchanged, and stir for 20-30 min; Adjust the stirring speed to 600-800 r / min, slowly add the coupling agent, stir for 15-20 min to hydrolyze the coupling agent and preliminarily react with the active groups in the system; then add the curing agent, continue to stir for 20-30 min to obtain a stable coating working solution; Cure the stable coating working solution at 25-30°C for 30-60 min to eliminate the air bubbles in the system, and obtain the BOPP reinforced coating working solution to ensure the stability of the coating working solution and the coating effect.

[0014] In a fourth aspect, the present application further provides a BOPP aluminum-coated film, which is prepared based on the BOPP reinforced coating according to the second aspect, and the BOPP reinforced coating is subjected to vacuum aluminum plating treatment to obtain the BOPP aluminum-coated film.

[0015] In some possible embodiments, the BOPP aluminum-coated film can be widely applied to high-barrier packaging in the fields of food, medicine, daily chemicals, electronics and the like which have requirements for low-temperature processing and long-term storage.

[0016] The BOPP reinforced coating working solution and the preparation method, the reinforced coating and the aluminum-coated film provided by the present application have the following advantages: 1. Excellent comprehensive performance, low-temperature heat-sealing advantage, introduction of a low-temperature heat-sealing modifier, synergistic water-based polyurethane main agent, silica sol, coupling agent and other components, and finally obtained BOPP reinforced coating has good aluminum-coated film firmness (3M adhesive tape peeling without falling off), excellent water boiling resistance (no aluminum layer falling off after immersion in 100°C boiling water for 1 h), strong chemical reagent resistance (resistant to 3% acetic acid, saturated brine and other medium erosion), outstanding barrier performance (oxygen barrier rate 0.5-0.8 cm 3 / (m2 • 24h·0.1MPa), water barrier 0.2-0.3g / (m 2 • 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, meeting the requirements of low-temperature processing technology and avoiding the influence of high-temperature heat sealing on the packaging contents.

[0017] 2. Long-term stability of barrier performance: The components of the BOPP reinforced coating working solution synergistically form a dense and stable coating structure. After 6 months of storage at room temperature, the attenuation rates of oxygen barrier and water barrier are both less than 5%, which is significantly better than existing coatings, and can effectively prolong the shelf life of the packaging contents.

[0018] 3. Environmental protection and safety: The water-based system uses water as the main solvent, supplemented with a small amount of isopropyl alcohol, without toxic and harmful solvent volatilization, meeting environmental protection requirements and reducing safety hazards in the production process.

[0019] 4. Good compatibility of formula: The low-temperature heat sealing modifier has high matching degree with other components, without delamination and precipitation. The prepared coating working solution has high stability and smooth coating process.

[0020] 5. Simple preparation process: Only the mixing step of the low-temperature heat sealing modifier is added based on the existing process, without the need for complex equipment and harsh reaction conditions, with high production efficiency and easy industrialization of large-scale production.

[0021] 6. Broader application prospect: The prepared BOPP aluminum-coated film can be widely used in high-barrier packaging of food, medicine, daily chemicals, electronics and other fields that require low-temperature processing and long-term storage, further expanding the market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The preparation method flowchart provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0024] The following performance tests were conducted on the examples and comparative examples: Aluminum-coated film adhesion: 3M tape peeling method was used, and the degree of aluminum layer peeling after peeling was divided into 1-5 levels (1 level is optimal, no peeling; 5 level is worst, large area peeling); Heat sealing strength: according to GB / T10004-2008 standard, under the conditions of heat sealing temperature 80℃, 100℃, 120℃, pressure 0.3MPa, time 1s; Boiling water resistance: soak in 100℃ boiling water for 1h, observe the integrity and whether the aluminum layer falls off; Chemical reagent resistance: soak in 3% acetic acid, saturated brine, ethanol, propanol, 3% hydrogen peroxide, etc. for 24h, respectively, observe the integrity and whether the aluminum layer falls off; Oxygen barrier rate: according to GB / T19789-2005, test the initial value and the value after 6 months of normal temperature storage, respectively; Water barrier rate: according to GB / T26253-2010, test the initial value and the value after 6 months of normal temperature storage, respectively.

[0025] Example 1 The present embodiment provides a BOPP reinforced coating working solution, the preparation raw materials are calculated by weight fraction, including: aliphatic water-based polyurethane dispersion (solid content is 35%) 100 parts, neutral silica sol (D50 particle size is 15nm) 1 part, polyoxyethylene alkyl phenol ether (non-ionic wetting agent) 0.8 parts, isopropyl alcohol 10 parts, water-based isocyanate curing agent 7 parts, γ-glycidyl ether oxypropyl trimethoxysilane (KH560) 1.2 parts, low temperature heat sealing modifier 3 parts, deionized water 160 parts.

[0026] The low temperature heat sealing modifier is mixed by polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer according to the weight ratio of 1:2.5.

[0027] The preparation method of the BOPP reinforced coating working solution, as shown in Figure 1 , includes the following steps: Preparation of raw materials: prepare the preparation raw materials according to the weight fraction, mix polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer, stir at 65℃ for 35min, cool to room temperature, and obtain the low temperature heat sealing modifier; Premixing: add the deionized water to the reaction container, start the stirring device, control the speed at 350r / min, then add isopropyl alcohol and low temperature heat sealing modifier, and stir for 12min.

[0028] Dispersion addition: under the stirring state, slowly add the water-based polyurethane main agent, stir for 18min, then sequentially add the silica sol and wetting agent, keep the stirring speed unchanged, and stir for 25min.

[0029] Crosslinking system construction: adjust the stirring speed to 700r / min, slowly add the coupling agent, stir for 18min, then add the curing agent, continue to stir for 25min, and obtain the stable coating working solution.

[0030] Maturation: The stable coating working solution is matured at 28℃ for 45min to obtain the BOPP reinforced coating working solution.

[0031] The embodiment provides a BOPP reinforced coating, and the BOPP reinforced coating working solution is coated on the surface of a BOPP substrate through an online coating process, the coating amount is controlled to be 2.0g / m², and the BOPP reinforced coating is obtained through drying and curing at 110℃ for 4s.

[0032] The embodiment provides a BOPP aluminum-plated film, and the BOPP reinforced coating is subjected to vacuum aluminum plating treatment to obtain the BOPP aluminum-plated film.

[0033] The performance test results are as follows:

[0034] Example 2 The embodiment provides a BOPP reinforced coating working solution, and the preparation raw materials are prepared according to weight parts, including: 100 parts of an aliphatic water-based polyurethane dispersion (solid content is 30%), 1.5 parts of neutral silica sol (D50 particle size is 10nm), 1 part of polyoxyethylene lauryl ether (non-ionic wetting agent), 15 parts of isopropyl alcohol, 5 parts of water-based isocyanate curing agent, 1.2 parts of γ-glycidyl ether oxypropyl trimethoxysilane (KH560), 2 parts of low-temperature heat sealing modifier and 160 parts of deionized water.

[0035] The low-temperature heat sealing modifier is obtained by mixing polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer at a weight ratio of 1:2.

[0036] The preparation method of the BOPP reinforced coating working solution comprises the following steps. Preparation: the preparation raw materials are prepared according to weight parts, and polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer are mixed and stirred at 60℃ for 40min, and then cooled to room temperature to obtain the low-temperature heat sealing modifier; Premixing: the deionized water is added to the reaction container, the stirring device is started, the rotating speed is controlled to be 300r / min, then the isopropyl alcohol and the low-temperature heat sealing modifier are added, and stirring is performed for 15min.

[0037] Dispersion and addition: under the stirring state, the water-based polyurethane main agent is slowly added, stirring is performed for 20min, then the silica sol and the wetting agent are sequentially added, the stirring speed is kept unchanged, and stirring is performed for 30min.

[0038] Crosslinking system construction: the stirring speed is adjusted to 600r / min, the coupling agent is slowly added, stirring is performed for 20min, then the curing agent is added, and stirring is continuously performed for 30min to obtain the stable coating working solution.

[0039] Maturation: The stable coating working solution is matured at 25℃ for 60min to obtain a BOPP reinforced coating working solution.

[0040] The present embodiment provides a BOPP reinforced coating, which is obtained by coating the BOPP reinforced coating working solution on the surface of a BOPP substrate through an online coating process, the coating amount is controlled at 1.5g / m², and the BOPP reinforced coating is obtained by drying and curing at 100℃ for 5s.

[0041] The present embodiment provides a BOPP aluminum-plated film, which is obtained by vacuum aluminum plating treatment on the BOPP reinforced coating, and the thickness of the aluminum layer is 35nm.

[0042] The performance test results are as follows:

[0043] Example 3 The present embodiment provides a BOPP reinforced coating working solution, and the preparation raw materials are prepared according to the weight parts, including: 100 parts of aliphatic water-based polyurethane dispersion (solid content is 40%), 0.8 parts of neutral silica sol (D50 particle size is 20nm), 1 part of polyoxyethylene octylphenyl ether (non-ionic wetting agent), 12 parts of isopropyl alcohol, 6 parts of water-based isocyanate curing agent, 1.4 parts of γ-glycidyl ether oxypropyl trimethoxysilane (KH560), 4 parts of low-temperature heat sealing modifier, and 160 parts of deionized water.

[0044] The low-temperature heat sealing modifier is obtained by mixing polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer at a weight ratio of 1:3.

[0045] The preparation method of the BOPP reinforced coating working solution comprises the following steps: Preparation of raw materials: The preparation raw materials are prepared according to the weight parts, and polyethylene glycol monomethyl ether acrylate and ethylene-vinyl acetate copolymer are mixed and stirred at 70℃ for 30min, and then cooled to room temperature to obtain a low-temperature heat sealing modifier; Pre-mixing: The deionized water is added to the reaction container, the stirring device is turned on, the rotating speed is controlled at 500r / min, then the isopropyl alcohol and the low-temperature heat sealing modifier are added, and the stirring is performed for 10min.

[0046] Dispersion and addition: Under the stirring state, the water-based polyurethane main agent is slowly added, the stirring is performed for 15min, then the silica sol and the wetting agent are sequentially added, the stirring speed is kept unchanged, and the stirring is performed for 20min.

[0047] Crosslinking system construction: The stirring speed is adjusted to 800r / min, the coupling agent is slowly added, the stirring is performed for 15min, then the curing agent is added, the stirring is continuously performed for 20min, and the stable coating working solution is obtained.

[0048] Maturation: the stable coating working solution was matured at 30℃ for 30 min to obtain the BOPP reinforced coating working solution.

[0049] This example provides a BOPP reinforced coating. The BOPP reinforced coating working solution was coated on the surface of the BOPP substrate by an online coating process, the coating amount was controlled at 2.5 g / m², and the BOPP reinforced coating was obtained by drying and curing at 120℃ for 3s.

[0050] This example provides a BOPP aluminum plated film. The BOPP reinforced coating was subjected to vacuum aluminum plating treatment to obtain a BOPP aluminum plated film, and the thickness of the aluminum layer was 45 nm.

[0051] The performance test results are as follows:

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that the amount of γ-glycidoxypropyltrimethoxysilane (KH560) is 0.

[0053] The performance test results are as follows:

[0054] Comparative Example 2 The difference between this comparative example and Example 1 is that the amount of low-temperature heat sealant is 0.

[0055] The performance test results are as follows:

[0056] Comparative Example 3 The difference between this comparative example and Example 1 is that the amount of water-based isocyanate curing agent is 2.

[0057] The performance test results are as follows:

[0058] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application 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.

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 polyoxyethylene alkylphenol ether, polyoxyethylene lauryl ether and polyoxyethylene octylphenol 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. The BOPP reinforced coating working fluid according to claim 1, characterized in that, 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.

7. A BOPP reinforced coating, based on the BOPP reinforced coating working fluid according to any one of claims 1-6, 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.

8. A method for preparing the BOPP reinforced coating working fluid according to any one of claims 1-7, 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.

9. A BOPP aluminized film, prepared based on the BOPP reinforced coating according to claim 7, characterized in that, The BOPP reinforced coating is subjected to vacuum aluminizing treatment to obtain the BOPP aluminized film.

10. The BOPP aluminized film according to claim 9, characterized in that, 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.

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