Self-destructive water-based resin film and preparation method thereof

Abstract

The invention provides a self-destruction water-based resin film, which is prepared from the following raw materials in parts by mass: 50 to 60 parts of water-based acrylic resin, 20 to 40 parts of water-based epoxy resin, 10 to 30 parts of water-based polyurethane resin, 1 to 10 parts of isocyanate cross-linking agent and 1 to 10 parts of amino cross-linking agent. The self-destroying water-based resin film is formed through resin premixing, cross-linking agent reaction, coating curing, glue coating, release paper covering and film stripping, the film is innovated through a water-based resin composite system and a cross-linking process, and breakage or irreversible appearance destroy during removal after pasting is achieved, so that the self-destroying water-based resin film is formed, and the service life of the self-destroying water-based resin film is prolonged. The method is suitable for the fields of anti-counterfeit labels, security seals, electronic equipment anti-tamper identifiers and the like, and has the remarkable advantages of environmental protection, low cost and efficient production.

Description

Technical Field

[0001] The present invention relates to the technical field of functional packaging materials. Background Art

[0002] According to GB / T25978-4.4.1.1.1, "Additional Requirements for Special-Purpose Labels," self-destructive labels must meet the following requirements: After the label removal test (5.3.12), the label must break and become inaccessible, or remain intact but exhibit cracks or deformation, resulting in incomplete label information. This requirement is widely used in applications such as automotive, electronics, and pharmaceuticals, where tamper-proof and reuse-resistant labels are strictly required.

[0003] Existing technical bottlenecks:

[0004] Solvent-based resin film: relies on organic solvents such as toluene and ethyl acetate to dissolve the resin, which poses an environmental problem of excessive VOC emissions; the curing process requires high-temperature drying to remove the solvent, and the curing time is as long as several hours (production speed is only 5m / min), with high energy consumption (1.5kWh / ㎡) and fire hazards; the high cost of special resin raw materials leads to high product prices.

[0005] Radiation-curing resin film: requires electron beam or ultraviolet irradiation equipment, and the initial equipment investment exceeds 10 million yuan; the production process has strict requirements on parameters such as irradiation dose and time, and process control is difficult; although curing can be achieved in seconds to minutes (production speed can reach 200m / min), the raw materials for special radiation-curing resins are scarce, and the procurement cost is 3-5 times higher than that of ordinary resins, making it difficult to achieve large-scale application.

[0006] With the expansion of the anti-counterfeiting and traceability market, there is an urgent need for a self-destructive film that uses water as a medium, has readily available raw materials, and has a simple process. While meeting national standard performance, it can achieve dual optimization of environmental protection and cost. Summary of the Invention

[0007] In order to solve the above problems existing in existing label films, the present invention provides a self-destructive water-based resin film.

[0008] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a self-destructive water-based resin film, and the raw materials for preparing the conductive water-based pressure-sensitive adhesive include, by weight:

[0009]

[0010] The raw materials for preparing the conductive water-based pressure-sensitive adhesive also include:

[0011] 0.1-0.3 parts of leveling agent

[0012] 0.1-0.3 parts of defoaming agent

[0013] 0.3-0.8 parts of catalyst.

[0014] Further optimization,

[0015]

[0016] Further optimization,

[0017] 0.2 parts of leveling agent

[0018] 0.2 parts of defoaming agent

[0019] 0.5 parts of catalyst.

[0020] A method for preparing a self-destructive water-based resin film comprises the following steps:

[0021] S1: Premix the resins: put 50-60 parts of waterborne acrylic resin, 20-40 parts of waterborne epoxy resin and 10-30 parts of waterborne polyurethane resin into a high-speed dispersing kettle, add 30-80 parts of deionized water and stir;

[0022] S2: Cross-linker reaction:

[0023] S21: Add 1-10 parts of isocyanate dropwise, and the stirring system becomes thick and milky white mist;

[0024] S22: Add 1-10 parts of amino crosslinking agent and continue stirring until the viscosity rises to 2000-3000 mPa·s;

[0025] S3: coating and curing:

[0026] S31: coating, the coating machine is applied to the PET release film;

[0027] S32: Curing:

[0028] The first stage of water evaporation: 50-100℃, 1-3min, the film surface changes from glossy to matte, and the weight loss is about 50-70%;

[0029] The second stage of pre-crosslinking: 80-120℃, 1-5min, the film layer is initially hardened and does not stick to the fingers when lightly pressed;

[0030] The third stage is complete cross-linking: 120-180℃, 3-10min, the film is completely hardened, and white scratches are left when scratched by fingernails;

[0031] S4: Glue coating and release paper lamination, gravure coating machine applies water-based pressure-sensitive adhesive and dries, laminar release paper, and rubber roller rolls at a pressure of 0.2-0.4 MPa;

[0032] S5: Film peeling: The tension control device peels off the PET release film, leaving the self-destructive resin film with the adhesive layer and release paper.

[0033] In step S1, 50 parts of water-based acrylic resin, 30 parts of water-based epoxy resin, and 20 parts of water-based polyurethane resin are put into a high-speed dispersing kettle, and 50 parts of deionized water are added. The mixture is first stirred at a low speed of 150 rpm to 300 rpm for 5 to 10 minutes, and then the speed is increased to 400 to 500 rpm and stirred for 20 to 30 minutes.

[0034] In step S21, 6 parts of isocyanate are slowly added dropwise and stirred at 500-1000 rpm for 5-15 minutes until the system thickens and becomes milky white mist;

[0035] In step S22, 4 parts of an amino cross-linking agent are added and stirring is continued for 3-10 minutes until the viscosity rises to 2000-3000 mPa·s;

[0036] The method further includes step S23: adding 0.1-0.3 parts of a leveling agent, 0.1-0.3 parts of a defoaming agent, and 0.3-0.8 parts of a catalyst, and stirring at 400 rpm-1000 rpm for 3-10 minutes.

[0037] In step S3, in step S31, a comma roll coater is used to coat a wet film with a thickness of 120 μm on a PET release film at a speed of 3-10 m / min;

[0038] Step S32:

[0039] The first stage of water evaporation: 80℃, 2min, the film surface changes from glossy to matte, and the weight loss is 60%;

[0040] The second stage of pre-crosslinking: 100℃ for 3 minutes, the film is initially hardened and does not stick to the fingers when lightly pressed;

[0041] The third stage is complete cross-linking: 150℃, 5min, the film is completely hardened, leaving white scratches when scratched by fingernails, and the cohesive strength is 25-30MPa.

[0042] In step S4, a gravure coater applies a water-based pressure-sensitive adhesive, which is then dried at 100° C. for 5 minutes, and immediately laminated with a release paper, and then rolled with a rubber roller at a pressure of 0.3 MPa.

[0043] In step S5, the tension control device peels off the PET release film at a uniform speed of 5-15 m / min at a tension of 15-20 N, leaving the self-destructive resin film with the adhesive layer and the release paper. The total thickness of the self-destructive resin film is 65-75 μm.

[0044] The self-destructive water-based resin film of the present invention achieves breakage or irreversible destruction of appearance when removed after pasting through the innovation of the water-based resin composite system and cross-linking process. It is suitable for anti-counterfeiting labels, security seals, electronic equipment anti-tampering labels and other fields, and has the significant advantages of environmental protection, low cost and efficient production. DETAILED DESCRIPTION

[0045] The self-destructive water-based resin film of the present invention achieves its self-destruction function through the technical path of "resin phase regulation - cross-linking density optimization - interface stress design":

[0046] 1. Multi-resin synergistic modification: Waterborne acrylic resin (soft phase, elongation at break 20-30%) is compounded with waterborne epoxy resin (hard phase, tensile strength ≥30MPa), and waterborne polyurethane resin (toughening phase) is introduced to form a ternary sea-island structure of "soft encapsulating hard-tough phase compatibilization", making the film both flexible and brittle failure potential;

[0047] 2. Dense network crosslinking: Isocyanate and amino crosslinking agent react with resin hydroxyl groups to form a three-dimensional crosslinked network with an average pore size of 30-50nm, which improves the cohesive strength of the film layer and forms stress concentration points at the adhesive interface;

[0048] 3. Process parameter matching: By controlling the coating thickness (65-75μm) and curing temperature (150℃), the film cohesive strength (25-30MPa) is lower than the adhesion between the adhesive and the substrate (0.4N / mm). During removal, the stress preferentially damages the film layer rather than the interface.

[0049] The raw material composition and proportion of the self-destructive water-based resin film of the present invention (multiple formula designs):

[0050]

[0051] The goal of the formula comparison experiment design is to screen the optimal ratio that takes into account both "self-destruction compliance rate" and "operational toughness" by adjusting the ratio of acrylic acid (soft phase), epoxy (hard phase), and polyurethane (tough phase).

[0052] Experimental group Acrylic acid (parts) Epoxy (parts) Polyurethane (parts) Expected performance trends A 60 20 20 High toughness, weak self-destruction B (Best) 50 40 10 Balance between self-destruction and resilience C 40 40 20 High hardness, reduced toughness D 60 10 30 Resilience is significantly improved, and self-destruction may be reduced

[0053] Experimental test results

[0054] Performance indicators Group A Group B Group C Group D Standard requirements Fracture rate 78％ 96％ 92％ 85％ ≥95％ Information destruction rate 65％ 91％ 88％ 75％ ≥90％ Elongation at break 55％ 28％ 15％ 65％ ≥20% (operation toughness) 180° bending cracking none Cracking Cracking none Cracking

[0055] Conclusion: Group B (5:3:2) is the best ratio: fracture rate 96%, information destruction rate 91%, fracture elongation 28%, and 180° bending cracking, which fully meets the core requirements of "fragile and tough".

[0056] Key mechanism: Acrylic acid provides initial flexibility, epoxy forms a hard phase brittle fracture skeleton, and polyurethane expands the capacity through flexible chain segments. The three work together to achieve a multi-stage failure mode of "soft phase breaks first - hard phase then brittle fracture - tough phase buffers and prevents brittle fracture".

[0057] The method for preparing the self-destructive water-based resin film of the present invention (based on the optimal ratio group B) is as follows:

[0058] S1: Resin premixing (30 minutes):

[0059] Put 50 parts of water-based acrylic resin, 30 parts of water-based epoxy resin, and 20 parts of water-based polyurethane resin into a high-speed dispersing kettle, add 50 parts of deionized water, stir at a low speed of 200 rpm for 5 minutes, then increase the speed to 400 rpm and stir for 25 minutes.

[0060] Control standards:

[0061] Qualified state: the slurry is uniform milky white, without particle stratification, and the particle size is ≤50μm (laser particle size analyzer detection, D50≤30μm); Abnormal treatment: If gel agglomeration occurs, add 5-10 parts of deionized water (5 parts is best) to dilute and extend the stirring to 30-40 minutes (40 minutes is best).

[0062] Note: Stirring temperature is less than 35℃ (jacket water cooling), and the feeding order is fixed as "resin → water" to avoid acrylic acid agglomeration when it comes into contact with water.

[0063] S2: Cross-linker reaction (20 minutes)

[0064] S21: Slowly add 6 parts of isocyanate dropwise (add within 2 minutes), stir at 600 rpm for 10 minutes, and the system becomes thick and milky white mist;

[0065] S22: Add 4 parts of amino crosslinker and continue stirring for 5 minutes until the viscosity rises to 3000 mPa.s (the flow time of 4 cups is 25-30 seconds, 30 seconds is optimal);

[0066] S23: Add 0.2 parts of leveling agent, 0.2 parts of defoaming agent, and 0.5 parts of catalyst (diluted to 0.5% concentration in advance), and stir at 500 rpm for 5 minutes.

[0067] Control standards:

[0068] Qualified state: There are no obvious bubbles in the prepolymer, and the glass rod is picked up to flow down in a continuous filamentous state (the flow stops within 3 seconds), and the pH value is 6.5-7.0; Abnormal treatment: If it gels quickly, immediately add 5-20 parts of deionized water (10 parts is optimal) to dilute it and shorten the subsequent curing time by 1-5% (3% is optimal); if there are too many bubbles, add 0.05-0.1 parts of defoaming agent (0.08 parts is optimal) and extend the stirring time by 1-5 minutes (3 minutes is optimal).

[0069] Note: Isocyanate must be handled in a fume hood, wearing chemical-resistant gloves and goggles; the catalyst cannot be added directly to the original solution to avoid local excessive cross-linking.

[0070] S3: Coating and curing (three-stage process):

[0071] S31: Coating: comma roll coater with a wet film thickness of 120 μm, coated on a PET release film (thickness 50 μm, surface tension 38 mN / m) at a speed of 5 m / min to ensure a smooth coating.

[0072] S32: Curing:

[0073] The first stage (water evaporation): 80℃, 2min, the film surface changes from glossy to matte, and the weight loss is about 60%;

[0074] The second stage (pre-crosslinking): 100℃, 3min, the film layer is initially hardened and does not stick to the fingers when lightly pressed;

[0075] The third stage (complete cross-linking): 150℃×5min, the film is completely hardened, and white scratches are left when scratched by a fingernail (cohesive strength 25-30MPa).

[0076] Control standards:

[0077] Acceptable: Film thickness 70±5μm, smooth surface without craters, and no sticking when peeling off the PET release film (peel force ≤5g / inch). Abnormal handling: If craters appear, add 0.05-0.1 parts of leveling agent (0.08 parts is optimal) and reduce the speed to 3-10m / min (5m / min is optimal). If the film is brittle, reduce the isocyanate content by 5-15% (10% is optimal) or lower the temperature to 130-145°C (140°C is optimal). Note: Maintain an oven temperature differential of ±2°C and clean the comma roller every 30 minutes to prevent the slurry from drying out.

[0078] S4: Glue coating and release paper lamination:

[0079] Apply water-based pressure-sensitive adhesive (wet film thickness 70μm) using a gravure coater, dry at 100℃ for 5 minutes (the adhesive layer is transparent and non-sticky), immediately laminate with release paper (weight 100-120g / ㎡, peel strength 10-20g / inch), and press with a rubber roller at a pressure of 0.3MPa. Control standards:

[0080] Qualified status: The light transmittance of the adhesive layer is uniform, and the release paper peeling force is 15±5g / inch;

[0081] Abnormal treatment: If there are many bubbles in the glue layer, reduce the temperature to 90℃ and extend the drying time to 8 minutes; if the edge is warped, adjust the gravure roller depth to 70μm.

[0082] Note: Preheat the release paper at 45℃ for 30 minutes in advance and clean the rubber roller regularly during rolling.

[0083] S5: Film peeling:

[0084] The tension control device (15-20N) peels off the PET release film at a constant speed of 10m / min, leaving the self-destructive resin film with the adhesive layer and release paper (total thickness 65-75μm).

[0085] Control standards:

[0086] Qualified status: The resin film is completely transferred, without tearing or PET residual glue (translucent and without bright spots);

[0087] Abnormal treatment: If the tear rate is greater than 5%, increase the third curing time by 2 minutes; if the residual glue is greater than 10%, pre-coat the PET surface with silane coupling agent to reduce adhesion.

[0088] Note: Keep the peeling tension stable to avoid stretching and deformation of the film layer (elongation ≤ 5%); waste PET should be collected separately and not mixed with ordinary garbage.

[0089] Performance testing plan:

[0090] 1. Substrate preparation: automotive amino paint board (paint film thickness 130μm, surface tension 35mN / m);

[0091] 2. Label pasting: Prepare a 40mm×60mm label, roll it with a 2kg roller (50mm wide) at a speed of 300mm / min, and place it in a standard environment for 14 days;

[0092] 3. Removal test: According to GB / T25978-5.3.12, manually peel off the label at a 45° angle and a speed of 30mm / min;

[0093] 4. Judgment criteria: fracture rate ≥ 95% or information destruction rate ≥ 90%, and no cracking after bending 180°.

[0094] Core advantages comparison:

[0095]

[0096] The present invention has the following advantages:

[0097] Environmentally friendly: 100% water-based ternary composite system, zero organic solvents, and all raw materials are commercially available general resins, significantly reducing costs; using water as the only dispersion medium, the VOC content is less than 5g / L, meeting strict environmental standards;

[0098] Cost advantage: Using commercially available general-purpose water-based resins and cross-linking agents, the production cost is reduced by more than 40% compared with similar technologies;

[0099] Efficient production: Conventional coating + three-stage curing is compatible with existing production lines. The equipment modification cost is only 1 / 5 of the traditional technology. The curing time is shortened to 10 minutes. Conventional coating equipment can be used for production, and production efficiency is increased by 50%;

[0100] Reliable self-destruction: The breakage rate is ≥95% or the information destruction rate is ≥90% when the label is removed, meeting the self-destruction requirements of GB / T25978. Performance balance: Through the 5:3:2 ratio of acrylic acid / epoxy / polyurethane, a "soft-hard-tough" multi-stage destruction mechanism is constructed, and the self-destruction compliance rate is improved by 10% compared to the binary system. At the same time, the elongation at break is maintained at 25-30%, avoiding operational brittle cracking. Through formula optimization, the synergy of "fragility" and "operational toughness" is achieved to avoid excessive brittle cracking of the film layer.

[0101] The present invention is described by way of example, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments may be modified to suit specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be within the scope of the present invention.

Claims

1. A self-destructive water-based resin film, characterized in that: The raw materials for preparing the conductive water-based pressure-sensitive adhesive include, by mass:

2. The self-destructive water-based resin film according to claim 1, characterized in that: The raw materials for preparing the conductive water-based pressure-sensitive adhesive also include: 0.1-0.3 parts of leveling agent 0.1-0.3 parts of defoaming agent 0.3-0.8 parts of catalyst.

3. The self-destructive water-based resin film according to claim 1, characterized in that: Further optimization, 4. The self-destructive water-based resin film according to claim 2, characterized in that: Further optimization, 0.2 parts of leveling agent 0.2 parts of defoaming agent 0.5 parts of catalyst.

5. A method for preparing a self-destructive water-based resin film, characterized in that: The following steps are involved: S1: Premix the resins: put 50-60 parts of waterborne acrylic resin, 20-40 parts of waterborne epoxy resin and 10-30 parts of waterborne polyurethane resin into a high-speed dispersing kettle, add 30-80 parts of deionized water and stir; S2: Cross-linker reaction: S21: Add 1-10 parts of isocyanate dropwise, and the stirring system becomes thick and milky white mist; S22: Add 1-10 parts of amino crosslinking agent and continue stirring until the viscosity rises to 2000-3000 mPa·s; S3: coating and curing: S31: coating, the coating machine is applied to the PET release film; S32: Curing: The first stage of water evaporation: 50-100℃, 1-3min, the film surface changes from glossy to matte, and the weight loss is about 50-70%; The second stage of pre-crosslinking: 80-120℃, 1-5min, the film layer is initially hardened and does not stick to the fingers when lightly pressed; The third stage is complete cross-linking: 120-180℃, 3-10min, the film is completely hardened, and white scratches are left when scratched by fingernails; S4: Glue coating and release paper lamination, gravure coating machine applies water-based pressure-sensitive adhesive and dries, laminar release paper, and rubber roller rolls at a pressure of 0.2-0.4 MPa; S5: Film peeling: The tension control device peels off the PET release film, leaving the self-destructive resin film with the adhesive layer and release paper.

6. The method for preparing a self-destructive water-based resin film according to claim 5, characterized in that: In step S1, 50 parts of water-based acrylic resin, 30 parts of water-based epoxy resin, and 20 parts of water-based polyurethane resin are put into a high-speed dispersing kettle, and 50 parts of deionized water are added. The mixture is first stirred at a low speed of 150 rpm to 300 rpm for 5 to 10 minutes, and then the speed is increased to 400 to 500 rpm and stirred for 20 to 30 minutes.

7. The method for preparing a self-destructive water-based resin film according to claim 5, wherein: In step S21, 6 parts of isocyanate are slowly added dropwise and stirred at 500-1000 rpm for 5-15 minutes until the system thickens and becomes milky white mist; In step S22, 4 parts of an amino cross-linking agent are added and stirring is continued for 3-10 minutes until the viscosity rises to 2000-3000 mPa·s; The method further includes step S23: adding 0.1-0.3 parts of a leveling agent, 0.1-0.3 parts of a defoaming agent, and 0.3-0.8 parts of a catalyst, and stirring at 400 rpm-1000 rpm for 3-10 minutes.

8. The method for preparing a self-destructive water-based resin film according to claim 5, wherein: In the step S3, Step S31: a comma roll coater is used to coat a wet film of 120 μm on a PET release film at a speed of 3-10 m / min. Step S32: The first stage of water evaporation: 80℃, 2min, the film surface changes from glossy to matte, and the weight loss is 60%; The second stage of pre-crosslinking: 100℃ for 3 minutes, the film is initially hardened and does not stick to the fingers when lightly pressed; The third stage is complete cross-linking: 150℃, 5min, the film is completely hardened, leaving white scratches when scratched by fingernails, and the cohesive strength is 25-30MPa.

9. The method for preparing a self-destructive water-based resin film according to claim 5, wherein: In step S4, a gravure coater applies a water-based pressure-sensitive adhesive, which is then dried at 100° C. for 5 minutes, and immediately laminated with a release paper, and then rolled with a rubber roller at a pressure of 0.3 MPa.

10. The method for preparing a self-destructive water-based resin film according to claim 5, wherein: In step S5, the tension control device peels off the PET release film at a uniform speed of 5-15 m / min at a tension of 15-20 N, leaving the self-destructive resin film with the adhesive layer and the release paper. The total thickness of the self-destructive resin film is 65-75 μm.

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