Laser transfer film and preparation method thereof

Abstract

The invention relates to the field of packaging materials, in particular to a laser transfer film and a preparation method thereof.The laser transfer film is composed of a base film, a laser transfer coating and an aluminum plating layer; the laser transfer coating is prepared from the following raw materials in parts by weight: 40-45 parts of polyurethane acrylate resin, 5-10 parts of phosphate modified hyperbranched epoxy resin, 5-10 parts of epoxy polysiloxane, 1-3 parts of a functional auxiliary agent and 180-220 parts of a solvent. The release capacity of the laser transfer coating and the base film is good, and the aluminum plating layer is free of delamination.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of packaging materials, in particular to a laser transfer film and a preparation method thereof. BACKGROUND

[0002] Laser transfer refers to the transfer of holographic images with rainbow dynamic and three-dimensional effect to the resin-coated base film through computer dot lithography technology, 3D true color holographic technology, multiple and dynamic imaging technology, etc. by molding, and then the film is coated, hot stamped, transferred and other ways to transfer specific patterns to the surface of the product packaging, so as to obtain a certain laser effect and make the appearance more beautiful. Laser packaging is a sub-industry in the packaging industry, which has developed rapidly in recent years. Compared with other products in the packaging industry, laser packaging materials not only have novel and beautiful appearance, but also have high-tech anti-counterfeiting function, and are known as the most advanced technology product in the world packaging and printing industry.

[0003] The laser transfer film in the prior art still has defects such as unclear base film peeling, low mechanical properties of laser coating, and easy delamination of aluminum plating layer, and technical improvement is still needed. SUMMARY

[0004] The present application provides a laser transfer film and a preparation method thereof to solve the above technical problems.

[0005] The technical scheme adopted is as follows: A laser transfer film, which is composed of a base film, a laser transfer coating and an aluminum plating layer. The laser transfer coating is made of the following raw materials by weight: Polyurethane acrylate resin 40-45 parts, phosphate modified hyperbranched epoxy resin 5-10 parts, epoxy-based polysiloxane 5-10 parts, functional additives 1-3 parts, and solvent 180-220 parts.

[0006] Further, the phosphate modified hyperbranched epoxy resin is obtained by reacting hyperbranched epoxy resin with alkyl phosphate.

[0007] Further, the structure of the hyperbranched epoxy resin is as follows: L1, L2 and L3 are the same or different, and each is independently an alkylene group, an alkenylene group or an alkynylene group.

[0008] Further, L1, L2 and L3 are the same, and each is independently an alkylene group with ≤10 carbon atoms.

[0009] Further, the structure of the alkyl phosphate is as follows: R1, R2 are the same or different, each independently alkyl, alkenyl or alkynyl.

[0010] Further, R1, R2 are the same, each independently alkyl with ≤10 carbon atoms.

[0011] Further, the epoxy polysiloxane is obtained by reacting hydrogen-containing silicone oil with epoxy olefin.

[0012] Further, the epoxy olefin has the following structure: Wherein, n≤10.

[0013] Further, the functional auxiliary agent includes any one or two or more combinations of defoaming agent, dispersant, emulsifier, anti-settling agent, stabilizer, anti-skinning agent, leveling agent, thickening agent, anti-sagging agent, preservative, flame retardant.

[0014] The application also provides a preparation method of the laser transfer film: The polyurethane acrylate resin, phosphate modified hyperbranched epoxy resin, epoxy polysiloxane, functional auxiliary agent and solvent are mixed uniformly to obtain laser transfer coating, the laser transfer coating is coated on the base film and dried to obtain laser transfer coating layer, the information on the die plate is transferred to the laser transfer coating layer under high temperature, and finally vacuum aluminum plating is performed to obtain the aluminum plating layer.

[0015] Has the following beneficial effects: The present application provides a laser transfer film, polyurethane acrylate resin as a base resin, polyurethane segment provides flexibility, and acrylate segment gives high hardness, balance coating in the high pressure resistance of the molding process and the elastic peeling when transferring, phosphate modified hyperbranched epoxy resin has a unique hyperbranched structure, low viscosity, and multiple functionality, which can reduce the viscosity of the system, improve the compatibility and coating leveling property of the base resin, and at the same time reduce the activation energy of the base resin, and improve the reaction curing rate. The epoxy group can also react with the carboxyl and hydroxyl groups in the polyurethane acrylate resin, increasing the crosslinking density, and the structure contains multiple ether bonds, which have the characteristics of long bond length and internal rotation, increasing the distance between crosslinking points and increasing the internal rotation ability of the molecular chain, thereby improving the flexibility of the molecular chain after curing, thereby achieving the purpose of toughening. The alkyl phosphate group can be coordinated with aluminum or polar adsorbed to improve the interfacial bonding force with the aluminum plating layer and avoid the occurrence of aluminum plating layer delamination. The epoxy-based polysiloxane can improve the release performance of the coating from the base film, and after adding it, the adhesion to the surface of the base film can be effectively reduced, thereby achieving the effect of smooth release and transfer. The introduction of the epoxy group can prevent the migration of the polysiloxane segment to the interface of the aluminum plating layer, which may be due to the participation of the epoxy group in the coating curing, thereby anchoring the polysiloxane segment at the coating / base film interface and preventing its migration and contamination of the aluminum plating layer interface. The laser transfer coating in the present application has excellent mechanical properties, and in the transfer process, the laser transfer coating has good release ability from the base film, and the aluminum plating layer does not delaminate. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The structure of the laser transfer film in Example 1 is shown in the figure, and the reference numbers in the figure represent: 1-BOPP base film, 2-laser transfer coating, 3-aluminum plating layer. DETAILED DESCRIPTION

[0017] Unless otherwise specified, the specific conditions in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market. The techniques not mentioned in the present application refer to the prior art, unless otherwise specified. The following examples and comparative examples are parallel tests, using the same processing steps and parameters.

[0018] The present application provides a laser transfer film, which is composed of a base film, a laser transfer coating and an aluminum plating layer: The laser transfer coating is made of the following raw materials by weight: Polyurethane acrylate resin 40-45 parts, phosphate modified hyperbranched epoxy resin 5-10 parts, epoxy-based polysiloxane 5-10 parts, functional additives 1-3 parts, solvent 180-220 parts.

[0019] The base film is selected from high molecular materials, and specifically can be PE, PET or BOPP.

[0020] The polyurethane acrylate resin is used as a base resin, the polyurethane segment in the structure provides flexibility, the acrylate segment endows high hardness, and the balance of the coating is high pressure resistance in the mold pressing process and elastic peeling during transfer.

[0021] The phosphate-modified hyperbranched epoxy resin has a unique hyperbranched structure, low viscosity and multiple functionality, can reduce the viscosity of the system, improve the compatibility and coating leveling property of the base resin, reduce the activation energy of the base resin, and improve the curing rate. The epoxy group can also react with the carboxyl and hydroxyl groups in the polyurethane acrylate resin, to increase the crosslinking density. The structure contains multiple ether bonds, the ether bond has the characteristics of long bond length and internal rotation, the distance between the crosslinking points is increased, the internal rotation ability of the molecular chain is increased, and the flexibility of the molecular chain after curing is improved, so that the toughening purpose is achieved. The alkyl phosphate group can be coordinated with aluminum or polar adsorbed, to improve the interfacial bonding force with the aluminum plating layer and avoid delamination of the aluminum plating layer during transfer of the coating.

[0022] The siloxane segment in the epoxy-based polysiloxane has extremely low surface energy, can migrate to the coating / base film interface during curing of the coating, form a “molecular level lubricating layer”, weaken the interfacial bonding force and reduce the interfacial energy. However, there is a risk of subsequent migration to the aluminum plating layer, which can cause a decrease in the interfacial strength with the aluminum plating layer. The introduction of the epoxy group can improve the effect to a certain extent, and the reason can be that the epoxy group participates in the curing of the coating, thereby anchoring the polysiloxane segment at the coating / base film interface, preventing the migration of the siloxane molecules to contaminate the interface of the aluminum plating layer, and avoiding the occurrence of delamination of the aluminum plating layer.

[0023] In one embodiment of the present application, the phosphate-modified hyperbranched epoxy resin is obtained by reacting a hyperbranched epoxy resin with an alkyl phosphate.

[0024] In one embodiment of the present application, the structure of the hyperbranched epoxy resin is as follows: L1, L2 and L3 are the same or different, and each is independently an alkylene group, an alkenylene group or an alkynylene group.

[0025] In one embodiment of the present application, L1, L2 and L3 are the same, and each is independently an alkylene group with ≤10 carbon atoms.

[0026] Specifically, the alkylene group with ≤10 carbon atoms is a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group or a decylene group.

[0027] In one of the embodiments of the present application, L1, L2, L3 are the same, and each is ethylene.

[0028] In one of the embodiments of the present application, the alkyl phosphate has the following structure: R1 and R2 are the same or different, and each is independently alkyl, alkenyl or alkynyl.

[0029] In one of the embodiments of the present application, R1 and R2 are the same, and each is independently alkyl with ≤10 carbon atoms.

[0030] The alkyl with ≤10 carbon atoms is specifically methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl.

[0031] In one of the embodiments of the present application, the epoxy polysiloxane is obtained by reacting hydrogen-containing silicone oil with epoxy olefin.

[0032] In one of the embodiments of the present application, the epoxy olefin has the following structure: In the formula, n ≤ 10.

[0033] In one of the embodiments of the present application, the functional adjuvant includes any one or a combination of two or more of defoaming agent, dispersant, emulsifier, anti-settling agent, stabilizer, anti-skinning agent, leveling agent, thickening agent, anti-sagging agent, preservative and flame retardant.

[0034] In one of the embodiments of the present application, the functional adjuvant is composed of defoaming agent and leveling agent.

[0035] In one of the embodiments of the present application, the solvent is composed of ethyl acetate and propylene glycol methyl ether acetate.

[0036] The present application also provides a preparation method of the laser transfer film. The polyurethane acrylate resin, phosphate-modified hyperbranched epoxy resin, epoxy polysiloxane, functional adjuvant and solvent are mixed uniformly to obtain laser transfer coating, the laser transfer coating is coated on the base film and dried to obtain laser transfer coating layer, the information on the die plate is transferred to the laser transfer coating layer under high temperature, and finally vacuum aluminum plating is performed to obtain aluminum plating layer.

[0037] Example 1: A laser transfer film is composed of BOPP base film 1, laser transfer coating layer 2 and aluminum plating layer 3. The laser transfer coating layer 2 is made of the following raw materials in parts by weight: Polyurethane acrylate resin 42 parts, phosphate-modified hyperbranched epoxy resin 8 parts, epoxy-based polysiloxane 6 parts, defoaming agent BYK-054 0.5 parts, leveling agent BYK-333 0.5 parts, ethyl acetate 160 parts, propylene glycol methyl ether acetate 40 parts; The preparation method of the phosphate-modified hyperbranched epoxy resin is as follows: Under nitrogen protection, trichlorobenzene (181.45 g, 1 mol) was dissolved in 1000 ml of dimethylbenzene to obtain a uniform solution. Ethylene glycol (186 g, 3 mol) was added to the reaction kettle, and under nitrogen protection, the temperature was raised to 80°C. Sodium hydroxide (128 g, 3.2 mol) was added in multiple portions, and after 60 min of incubation and stirring, the trichlorobenzene solution was added dropwise. After the dropwise addition was completed, the temperature was raised to reflux for 5 h. After the reaction was completed, the reaction liquid was cooled to room temperature and washed with deionized water three times (1000 ml x 3). The organic phase was dried with anhydrous sodium sulfate and then distilled under reduced pressure to obtain a hyperbranched alcohol with a yield of 85.7%. ESI-MS (m / z) (M + ): Theoretical value 258.27, actual value 258.44, HPLC purity 99.2%.

[0038] Under nitrogen protection, the hyperbranched alcohol (129.14 g, 0.5 mol), epichlorohydrin (138.78 g, 1.5 mol), and 1000 ml of dimethylbenzene were added to the reaction kettle. The temperature was raised to 80°C, and sodium hydroxide (68 g, 1.7 mol) was added in multiple portions. The temperature was raised to reflux for 5 h. After the reaction was completed, the reaction liquid was cooled to room temperature and washed with deionized water three times (1000 ml x 3). The organic phase was dried with anhydrous sodium sulfate and then distilled under reduced pressure to obtain a hyperbranched epoxy resin with a yield of 77.5%. ESI-MS (m / z) (M + ): Theoretical value 426.46, actual value 426.19, HPLC purity 83.5%.

[0039] Phosphodiethyl ester with a molar ratio of 1:1 was added to the hyperbranched epoxy resin. The mixture was reacted at 85°C for 2 h under stirring, and then incubated at 75°C for another 30 min. After cooling, the phosphodiethyl ester-modified hyperbranched epoxy resin was obtained, with an epoxy value of 0.34 mol / 100 g.

[0040] The preparation method of the epoxy-based polysiloxane is as follows: A three-necked flask was charged with hydrogen-containing silicone oil and 1,2-epoxy-5-hexene. The molar ratio of Si-H bond to C=C was 1:1.2. The temperature was raised to 85°C. A catalyst, hexahydrated chloroplatinic acid, was slowly added to the three-necked flask. The concentration of the catalyst was 8 ppm. After 6 h of reaction, the reaction liquid was distilled under reduced pressure to obtain the epoxy-based polysiloxane.

[0041] The preparation method of the above laser transfer film is as follows: The polyurethane acrylate resin, phosphate modified hyperbranched epoxy resin, epoxy-based polysiloxane, defoaming agent BYK-054, leveling agent BYK-333, ethyl acetate and propylene glycol methyl ether acetate are mixed uniformly to obtain a laser transfer coating, the laser transfer coating is coated on the BOPP base film 1 and dried and cured to obtain a laser transfer coating layer 2, and the coating wet amount is controlled at 5-8 g / m 2 The die plate is heated to 170±10℃, the information on the die plate is transferred to the laser transfer coating layer 2 in a high-temperature state, the aluminum wire is heated to vaporization under the vacuum condition of 0.04 Pa, and vacuum aluminum plating is performed to obtain an aluminum plating layer 3.

[0042] After the peeling test, the laser transfer coating layer 2 is transferred normally, and no delamination occurs in the aluminum plating layer 3.

[0043] Example 2: The laser transfer coating layer 2 is prepared from the following raw materials in parts by weight: polyurethane acrylate resin 40 parts, phosphate modified hyperbranched epoxy resin 5 parts, epoxy-based polysiloxane 5 parts, defoaming agent BYK-054 0.5 parts, leveling agent BYK-333 0.5 parts, ethyl acetate 160 parts, and propylene glycol methyl ether acetate 40 parts; After the peeling test, the laser transfer coating layer 2 is transferred normally, and no delamination occurs in the aluminum plating layer 3.

[0044] Example 3: The laser transfer coating layer 2 is prepared from the following raw materials in parts by weight: polyurethane acrylate resin 45 parts, phosphate modified hyperbranched epoxy resin 10 parts, epoxy-based polysiloxane 10 parts, defoaming agent BYK-054 0.5 parts, leveling agent BYK-333 0.5 parts, ethyl acetate 160 parts, and propylene glycol methyl ether acetate 40 parts; After the peeling test, the laser transfer coating layer 2 is transferred normally, and no delamination occurs in the aluminum plating layer 3.

[0045] Comparative Example 1: The laser transfer coating layer 2 is prepared from the following raw materials in parts by weight: After the peeling test, the laser transfer coating layer 2 is transferred normally, and no delamination occurs in the aluminum plating layer 3.

[0046] Comparative Example 2: The laser transfer coating layer 2 is prepared from the following raw materials in parts by weight: After the peeling test, the laser transfer coating 2 was transferred normally, and no delamination occurred in the aluminum plating layer 3.

[0047] Comparative Example 3: The same as Example 1, except that the epoxy resin E-44 was used instead of the phosphate-modified hyperbranched epoxy resin; After the peeling test, the laser transfer coating 2 was transferred normally, and no delamination occurred in the aluminum plating layer 3.

[0048] Comparative Example 4: The same as Example 1, except that the epoxy-based polysiloxane was not added; After the peeling test, the laser transfer coating 2 was transferred normally, and no delamination occurred in the aluminum plating layer 3.

[0049] Comparative Example 5: The same as Example 1, except that the phosphate-modified hyperbranched epoxy resin was not added; After the peeling test, the laser transfer coating 2 was transferred normally, and no delamination occurred in the aluminum plating layer 3.

[0050] Comparative Example 6: The same as Example 1, except that the phosphate-modified hyperbranched epoxy resin and the epoxy-based polysiloxane were not added; After the peeling test, the laser transfer coating 2 was transferred normally, and no delamination occurred in the aluminum plating layer 3.

[0051] Performance Test The laser transfer coatings prepared in Examples 1-3 and Comparative Examples 1-6 were tested for performance.

[0052] The pencil hardness of the cured samples was determined according to GB / T6739-2006; The adhesion of the cured samples was determined according to GB / T9286-2021, with aluminum as the substrate; The impact resistance of the cured samples was determined according to GB / T1732-2020.

[0053] The test results are shown in Table 1 below: Table 1: As shown in Table 1 above, the laser transfer coating of the present application has excellent mechanical properties.

[0054] As shown in Table 1 above, the laser transfer coating of the present application has excellent mechanical properties.

[0055] From the data comparison of Example 1 and Comparative Examples 2-3, it can be seen that the addition of the phosphate-modified hyperbranched epoxy resin has a greater improvement in the performance of the coating than the epoxy resins E-51 and E-44.

[0056] From the data comparison of Example 1 and Comparative Examples 4-6, it can be seen that the addition of the phosphate-modified hyperbranched epoxy resin and the epoxy-based polysiloxane has a positive effect on the improvement in the performance of the coating.

[0057] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A laser transfer film, characterized in that, It consists of a base film, a laser transfer coating, and an aluminum plating layer: The laser transfer coating is made from the following raw materials in parts by weight: 40-45 parts of polyurethane acrylate resin, 5-10 parts of phosphate-modified hyperbranched epoxy resin, 5-10 parts of epoxy-based polysiloxane, 1-3 parts of functional additives, and 180-220 parts of solvent.

2. The laser transfer film as described in claim 1, characterized in that, The phosphate-modified hyperbranched epoxy resin is obtained by reacting hyperbranched epoxy resin with alkyl phosphate ester.

3. The laser transfer film as described in claim 2, characterized in that, The structural formula of the hyperbranched epoxy resin is shown below: L1, L2, and L3 may be the same or different, and each can be independently alkylene, alkenylene, or yntylide.

4. The laser transfer film as described in claim 3, characterized in that, L1, L2, and L3 are the same, and each is an alkylene group with ≤10 carbon atoms.

5. The laser transfer film as described in claim 2, characterized in that, The structural formula of the alkyl phosphate is shown below: R1 and R2 may be the same or different, and each can be alkyl, alkenyl or alkynyl.

6. The laser transfer film as described in claim 5, characterized in that, R1 and R2 are the same, and each is an alkyl group with ≤10 carbon atoms.

7. The laser transfer film as described in claim 1, characterized in that, The epoxy-based polysiloxane is obtained by reacting hydrogen-containing silicone oil with epoxy-based olefins.

8. The laser transfer film as described in claim 7, characterized in that, The structural formula of the epoxy-based olefin is shown below: Where n≤10.

9. The laser transfer film as described in claim 1, characterized in that, The functional additives include any one or a combination of two or more of the following: defoamers, dispersants, emulsifiers, antisettling agents, stabilizers, anti-skinning agents, leveling agents, thickeners, anti-sagging agents, preservatives, and flame retardants.

10. A method for preparing a laser transfer film as described in any one of claims 1-9, characterized in that, A laser transfer coating is prepared by uniformly mixing polyurethane acrylate resin, phosphate-modified hyperbranched epoxy resin, epoxy polysiloxane, functional additives and solvent. The laser transfer coating is then applied to a base film and dried to obtain a laser transfer coating layer. Information from a molding die is then hot-stamped onto the laser transfer coating layer at a high temperature. Finally, a metallized layer is obtained by vacuum metallization.

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