A strippable coating composition capable of simultaneous UV offset printing and gravure printing and a preparation method thereof

Abstract

The present invention discloses a strippable coating composition that can be used for UV offset printing and gravure printing at the same time, comprising: 8 to 15 parts of high Tg polyacrylate resin, 0 to 10 parts of low Tg polyacrylate resin, 1 to 5 parts of modified terminal vinyl polybutadiene resin, 1 to 9 parts of cellulose ester resin, 0 to 0.3 parts of auxiliary agent, and 70 to 85 parts of solvent, wherein the modified terminal vinyl polybutadiene resin is prepared by end-capping reaction of terminal isocyanate polybutadiene resin using hydroxy acrylate. The preparation method is as follows: the solvent is put into a reaction kettle, and after heating and stirring evenly, the material to be dissolved is put into the reaction kettle and stirred and dissolved evenly, and then the auxiliary agent is added and stirred evenly, and the product can be obtained by cooling and filtering. The present invention introduces the modified terminal vinyl polybutadiene resin into the coating system, and the unsaturated bonds of the modified terminal vinyl polybutadiene resin can be opened during UV offset printing, and the resin participates in the curing reaction of the offset ink, and an interfacial reaction is formed at the interface between the ink and the coating, thereby increasing the interlayer fastness, and will not affect the performance of the system itself in terms of solvent resistance of the coating coating, so the modified terminal vinyl polybutadiene resin can also be used for gravure printing.

Description

Technical Field

[0001] The invention belongs to the field of coatings, and in particular relates to a strippable coating composition capable of simultaneous UV offset printing and gravure printing and a preparation method thereof. Background Art

[0002] Holographic laser packaging combines beauty and anti-counterfeiting, and is now widely used in the packaging and printing industry, especially in the tobacco packaging industry. In order to present different visual effects to the packaged products, using ink to print on the surface of the holographic embossed coating is an indispensable process in the packaging industry. The current printing applications in the packaging field are mostly gravure printing and offset printing. Because gravure printing requires good solvent resistance of the coating, while offset printing is just the opposite, requiring poor solvent resistance of the coating. The holographic embossed peelable coating currently on the market can only meet the requirements of one of the gravure printing process or the offset printing process, and cannot meet the requirements of both printing processes at the same time, which results in many product models and many stocking requirements, and also brings many inconveniences to downstream customers. For example, patent CN101760107A, which discloses a laser aluminum-plated transfer coating suitable for gravure printing and a preparation method thereof, but it is only for gravure printing, and another example is patent CN102352162A, which discloses a UV offset transfer laser coating and a synthesis method thereof, which is also for a single offset printing process. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, a strippable coating composition capable of both UV offset printing and gravure printing is provided, wherein the strippable coating composition capable of both UV offset printing and gravure printing comprises the following components in weight percentage: 8 to 15 parts of a high Tg polyacrylate resin, 0 to 10 parts of a low Tg polyacrylate resin, 1 to 5 parts of a modified vinyl-terminated polybutadiene resin, 1 to 9 parts of a cellulose ester resin, 0 to 0.3 parts of an auxiliary agent, and 70 to 85 parts of a solvent, wherein the modified vinyl-terminated polybutadiene resin is prepared by end-capping an isocyanate-terminated polybutadiene resin using a hydroxy acrylate.

[0005] Preferably, the preparation method of the modified vinyl-terminated polybutadiene resin is as follows: hydroxy acrylate and isocyanate-terminated polybutadiene resin are added to a reaction kettle in a molar ratio of 2:1, and then heated to 60-70° C. with stirring, and reacted for 4-5 hours until no isocyanate group is detected, thereby obtaining the modified vinyl-terminated polybutadiene resin.

[0006] Preferably, the hydroxyacrylate is one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, and hydroxypropyl acrylate.

[0007] Preferably, the isocyanate content of the isocyanate-terminated polybutadiene resin is 5-7% or 1.8-2.58%.

[0008] Preferably, the high Tg polyacrylate is a polymer formed by polymerization of one or more monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, and ethyl acrylate, and the high Tg polyacrylate has a glass transition temperature of 80 to 110° C. and a molecular weight of 30,000 to 140,000.

[0009] Preferably, the low Tg polyacrylate is a polymer formed by polymerization of one or more monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, and ethyl acrylate, and the glass transition temperature of the low Tg polyacrylate is 20 to 50° C. and the molecular weight is 20,000 to 100,000.

[0010] Preferably, the cellulose ester resin is one or more of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate with a molecular weight of 20,000 to 100,000.

[0011] Preferably, the solvent is one or more of ethyl acetate, n-propyl acetate, n-butyl acetate, ethanol, n-propanol, isopropanol, acetone, butanone, propylene glycol methyl ether, and propylene glycol ethyl ether.

[0012] Preferably, the auxiliary agent is one or more of a leveling agent, a defoaming agent, and an anti-scratch agent; the leveling agent is one or more of Flow300, Glide410, Glide435, Glide450, Glide432, BYK-306, BYK-333, BYK-323, BYK-358N, BYK-354, DC11, DC67, DC57, DC56, DC54, and DC5211; the defoaming agent is one or more of BYK-141, BYK-052, BYK-051, BYK-066N, BYK-0234, Airex900, Airex910, Airex920, Airex9313, DC163, DC62, and DC65; and the anti-scratch agent is one or more of DC51, DC52, DC29, DC27, and DC18.

[0013] A method for preparing a strippable coating composition capable of simultaneous UV offset printing and gravure printing, comprising:

[0014] Step 1: Add the solvent into the reaction kettle, then heat it to 45-55° C. and maintain the stirring speed at 60-100 rpm;

[0015] Step 2: Add high Tg polyacrylate resin, low Tg polyacrylate resin, modified vinyl-terminated polybutadiene resin, cellulose ester resin and additives into the reaction kettle, and continue stirring for 1.5 to 3 hours;

[0016] Step 3: Add the auxiliary agent into the reaction kettle, stir for 0.5 to 1 hour and then stop stirring, cool the product and filter it, and then package it to obtain a strippable coating composition product that can be used for both UV offset printing and gravure printing.

[0017] The present invention has at least the following beneficial effects:

[0018] (1) The system provided by the present invention has a production process and a use process that are completely consistent with the production and use process of existing products, and does not require modification of existing equipment and processes. It is simple and easy to operate in terms of practicality;

[0019] (2) The modified vinyl-terminated polybutadiene resin introduced into the coating system can open its unsaturated bonds during UV offset printing, participate in the curing reaction of the offset ink, form an interfacial reaction at the interface between the ink and the coating, and increase the interlayer fastness. Since this system itself does not affect the solvent resistance of the coating, the solvent in the gravure ink system will not have a negative impact on the coating, so this system can meet the requirements of both offset and gravure printing;

[0020] (3) Polybutadiene resin has excellent flexibility. The introduction of groups can improve the flexibility of the coating and improve offset printing ink burst.

[0021] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0022] The present invention is described in further detail below so that those skilled in the art can implement it according to the description.

[0023] Example 1

[0024] A method for preparing a strippable coating composition capable of simultaneous UV offset printing and gravure printing, comprising:

[0025] Step 1: 15 kg of ethyl acetate, 20 kg of butanone, 15 kg of n-propyl acetate and 10 kg of propylene glycol methyl ether were placed in a reaction kettle as solvents by weight, the reaction kettle was heated to 50° C., a stirring device was turned on, and the stirring speed was maintained at 100 rpm for uniform stirring;

[0026] Step 2: Add 8kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg 90°C, molecular weight 70,000), 2kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 30°C, molecular weight 75,000), 1kg of cellulose acetate butyrate resin, and 1kg of modified vinyl-terminated polybutadiene resin into the reactor by weight, and continue stirring for 2h;

[0027] Step 3: Add 0.01 kg of leveling agent BYK-333 into the reactor, stir for 1 hour until uniform, then stop stirring, cool the product to 20° C., filter it, and then package it to obtain a strippable coating composition product that can be used for both UV offset printing and gravure printing.

[0028] Among them, the preparation method of the modified terminal vinyl polybutadiene resin in step 2 is: 0.260 kg of hydroxypropyl acrylate and 2.1 kg of terminal isocyanate polybutadiene resin (isocyanate content 2%) are added to a reactor, and then heated to 65° C. with stirring, and the temperature fluctuation is controlled to be 1° C., and the reaction is performed for 4.5 hours until no isocyanate group is detected, so as to obtain the modified terminal vinyl polybutadiene resin.

[0029] Example 2

[0030] A method for preparing a strippable coating composition capable of simultaneous UV offset printing and gravure printing, comprising:

[0031] Step 1: 35 kg of ethyl acetate, 25 kg of butanone, 20 kg of n-propyl acetate and 15 kg of propylene glycol methyl ether were placed in a reaction kettle as solvents by weight, the reaction kettle was heated to 60° C., a stirring device was turned on, and the stirring speed was maintained at 100 rpm for uniform stirring;

[0032] Step 2: Add 16 kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and ethyl methacrylate, Tg 100°C, molecular weight 65,000), 9 kg of cellulose acetate resin, 10 kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 25°C, molecular weight 70,000), and 5 kg of modified vinyl-terminated polybutadiene resin into the reactor by weight, and continue stirring for 2 hours;

[0033] Step 3: Add 0.3 kg of leveling agent BYK-333 into the reactor, stir for 1 hour until uniform, then stop stirring, cool the product to 20° C., filter it, and then package it to obtain a strippable coating composition product that can be used for both UV offset printing and gravure printing.

[0034] Among them, the preparation method of the modified terminal vinyl polybutadiene resin in step 2 is: 1.392 kg of hydroxyethyl acrylate and 4.2 kg of terminal isocyanate polybutadiene resin (isocyanate content 6%) are added to a reactor, and then heated to 68° C. with stirring, and the temperature fluctuation is controlled to be 1° C., and the reaction is carried out for 4 hours until no isocyanate group is detected, so as to obtain the modified terminal vinyl polybutadiene resin.

[0035] Example 3

[0036] A method for preparing a strippable coating composition capable of simultaneous UV offset printing and gravure printing, comprising:

[0037] Step 1: 20 kg of ethyl acetate, 20 kg of butanone, 20 kg of n-propyl acetate and 10 kg of propylene glycol methyl ether were placed in a reaction kettle as solvents by weight, the reaction kettle was heated to 60° C., a stirring device was turned on, and the stirring speed was maintained at 100 rpm for uniform stirring;

[0038] Step 2: Add 12kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg85°C, molecular weight 60,000), 5kg of cellulose acetate propionate resin, 5kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg40°C, molecular weight 80,000) and 3kg of modified vinyl-terminated polybutadiene resin into the reactor by weight, and continue stirring for 2h;

[0039] Step 3: Add 0.15 kg of leveling agent Glide 450 into the reactor, stir for 1 hour until uniform, then stop stirring, cool the product to 20° C., filter, and then package to obtain a strippable coating composition product that can be used for both UV offset printing and gravure printing.

[0040] Among them, the preparation method of the modified terminal vinyl polybutadiene resin in step 2 is: 1.04kg hydroxyethyl methacrylate and 2.8kg terminal isocyanate polybutadiene resin (isocyanate content 6%) are added to a reactor, and then heated to 60°C under stirring, the temperature fluctuation is controlled to be 1°C, and the reaction is performed for 5 hours until no isocyanate group is detected, so as to obtain the modified terminal vinyl polybutadiene resin.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 1 is that step 2 is: 8 kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg 90°C, molecular weight 70000), 2 kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 30°C, molecular weight 75000), and 2 kg of cellulose acetate butyrate resin are added to the reaction kettle by weight, and stirring is continued for 2 hours;

[0043] The remaining steps are consistent with the preparation method of Example 1.

[0044] Comparative Example 2

[0045] The difference between this comparative example and Example 1 is that step 2 is: 8 kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg 90°C, molecular weight 70000), 2 kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 30°C, molecular weight 75000), 1 kg of cellulose acetate butyrate resin, and 1 kg of isocyanate-terminated polybutadiene resin are added to the reaction kettle by weight, and stirring is continued for 2 hours;

[0046] The remaining steps are consistent with the preparation method of Example 1.

[0047] Comparative Example 3

[0048] The difference between this comparative example and Example 1 is that step 2 is: 8 kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg 90°C, molecular weight 70000), 2 kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 30°C, molecular weight 75000), 1 kg of cellulose acetate butyrate resin, and 1 kg of hydroxypropyl acrylate are added to the reaction kettle by weight, and stirring is continued for 2 hours;

[0049] The remaining steps are consistent with the preparation method of Example 1.

[0050] Comparative Example 4

[0051] The difference between this comparative example and Example 1 is that step 2 is: 8 kg of high Tg polyacrylate resin (copolymer of methyl methacrylate and butyl methacrylate, Tg 90°C, molecular weight 70000), 2 kg of low Tg polyacrylate resin (copolymer of methyl methacrylate and butyl acrylate, Tg 30°C, molecular weight 75000), 1 kg of cellulose acetate butyrate resin, 0.11 kg of hydroxypropyl acrylate and 0.89 kg of isocyanate-terminated polybutadiene resin are added to the reaction kettle by weight, and stirring is continued for 2 hours;

[0052] The remaining steps are consistent with the preparation method of Example 1.

[0053] Examples 1 to 3 and comparative examples 1 to 4 were tested as follows. Test samples were prepared by applying the coating to the surface of the PET film using a coating rod, placing the film in an oven at 110°C for 10 to 15 seconds, then vacuum aluminum plating by die pressing, applying glue and laminating the film to the cardboard, drying the water, peeling off the PET base film, transferring the coating to the cardboard, and printing the ink on the coating surface according to two printing types: UV161 series offset ink and JF602 series gravure ink for testing. The test results are shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] As can be seen from Table 1, the strippable coating compositions for simultaneous UV offset printing and gravure printing prepared in Examples 1 to 3 of the present invention can show normal printing performance when used for UV offset printing and gravure printing due to the addition of modified terminal vinyl polybutadiene resin, that is, they can be used for UV offset printing and gravure printing at the same time. However, the modified terminal vinyl polybutadiene resin was not added during the preparation of the coating of Comparative Example 1, which is equivalent to preparing an ordinary gravure coating, which can only be used normally for gravure printing, and the ink layer will be detached during UV offset printing. Hydroxypropyl acrylate was added during the preparation of the coating of Comparative Example 3. Since the added hydroxypropyl acrylate is a small molecule, its gravure printing performance will be reduced, and the coating will dissolve and bloom. It still cannot be used for UV offset printing. The ink layer will be detached during UV offset printing, and the coating will have a slight blooming phenomenon. In Comparative Examples 2 and 4, unmodified terminal isocyanate polybutadiene resin was added during the preparation process, which will cause problems in the storage stability of the coating, and a complete product cannot be prepared, and subsequent tests cannot be continued.

[0058] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A strippable coating composition capable of simultaneous UV offset printing and gravure printing, characterized in that: The strippable coating composition capable of both UV offset printing and gravure printing comprises the following components in weight percentage: 8-15 parts of a high Tg polyacrylate resin, 0-10 parts of a low Tg polyacrylate resin, 1-5 parts of a modified vinyl-terminated polybutadiene resin, 1-9 parts of a cellulose ester resin, 0-0.3 parts of an auxiliary agent, and 70-85 parts of a solvent. The modified vinyl-terminated polybutadiene resin is obtained by performing a capping reaction on an isocyanate-terminated polybutadiene resin using a hydroxy acrylate.

2. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The preparation method of the modified vinyl-terminated polybutadiene resin is as follows: hydroxy acrylate and isocyanate-terminated polybutadiene resin are added into a reaction kettle in a molar ratio of 2:1, and then heated to 60-70° C. under stirring, and reacted for 4-5 hours until no isocyanate group is detected, so as to obtain the modified vinyl-terminated polybutadiene resin.

3. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 2, characterized in that: The hydroxyacrylate is one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate and hydroxypropyl acrylate.

4. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 2, characterized in that: The isocyanate content of the isocyanate-terminated polybutadiene resin is 5-7% or 1.8-2.58%.

5. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The high Tg polyacrylate is a polymer formed by polymerization of one or more monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, and ethyl acrylate. The high Tg polyacrylate has a glass transition temperature of 80-110° C. and a molecular weight of 30,000-140,000.

6. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The low Tg polyacrylate is a polymer formed by polymerization of one or more monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, and ethyl acrylate. The low Tg polyacrylate has a glass transition temperature of 20-50° C. and a molecular weight of 20,000-100,000.

7. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The cellulose ester resin is one or more of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate with a molecular weight of 20,000 to 100,000.

8. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The solvent is one or more of ethyl acetate, n-propyl acetate, n-butyl acetate, ethanol, n-propanol, isopropanol, acetone, butanone, propylene glycol methyl ether, and propylene glycol ethyl ether.

9. The strippable coating composition capable of simultaneous UV offset printing and gravure printing according to claim 1, characterized in that: The auxiliary agent is one or more of a leveling agent, a defoaming agent, and an anti-scratch agent. The leveling agent is one or more of Flow300, Glide410, Glide435, Glide450, Glide432, BYK-306, BYK-333, BYK-323, BYK-358N, BYK-354, DC11, DC67, DC57, DC56, DC54, and DC5211; the defoaming agent is one or more of BYK-141, BYK-052, BYK-051, BYK-066N, BYK-0234, Airex900, Airex910, Airex920, Airex9313, DC163, DC62, and DC65; and the anti-scratch agent is one or more of DC51, DC52, DC29, DC27, and DC18.

10. A method for preparing a strippable coating composition capable of simultaneous UV offset printing and gravure printing according to any one of claims 1 to 9, comprising: Step 1: Add the solvent into the reaction kettle, then heat it to 45-55°C and maintain the stirring speed at 60-100 rpm; Step 2: Add high Tg polyacrylate resin, low Tg polyacrylate resin, modified vinyl-terminated polybutadiene resin and cellulose ester resin into the reaction kettle and continue stirring for 1.5 to 3 hours; Step 3: Add the auxiliary agent into the reaction kettle, stir for 0.5 to 1 hour and then stop stirring, cool the product and filter it, and then package it to obtain a strippable coating composition product that can be used for both UV offset printing and gravure printing.

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