An aqueous release coating, its preparation method and application

Abstract

The present invention discloses an aqueous release coating, which comprises the following components by mass percentage: paraffin emulsion 30-40%, palm wax emulsion 30-40%, polyethylene wax emulsion 15-30%, release force regulator 1-3%, surfactant 1-3%, and aqueous polymer resin 1-3%. The present invention also discloses a preparation method of the aqueous release coating and its application in thermal transfer labels. The aqueous release coating disclosed by the present invention has no ink residue on the surface of the paper after release, and the aqueous release coating does not add organic solvents, has no VOC emissions, is environmentally friendly, has low cost, and the raw materials are friendly to the human body, and can be applied to the fields where human contact is possible.

Description

Technical Field

[0001] The invention relates to the technical field of label printing, and in particular to a water-based release coating and a preparation method and application thereof. Background Art

[0002] Release agent is a kind of isolation film applied between the product and the mold to prevent the formed composite product from sticking to the mold, so that the product can be easily removed from the mold, while ensuring the surface quality of the product and the mold are intact. In recent years, thermal transfer printing technology has received widespread attention at home and abroad. Thermal transfer, also known as hot stamping, is a method of transferring text or patterns printed on thermal transfer paper or plastic film to fabric or leather by heating and pressurizing. Its advantages are bright colors and rich layers of transferred images. Among them, release agent is the core content of thermal transfer technology and is the decisive factor in whether the ink can be effectively attached to the surface of the substrate. Release agent plays a role in buffering the adhesion of the substrate and the printing layer, and has good wear resistance, which can protect the color ink and extend the service life of the ink.

[0003] At present, the thermal transfer labels in the prior art mainly use PET film as a carrier. PET film is a petroleum derivative and is non-renewable. Paper substrates have gradually replaced PET films in thermal transfer labels due to their renewable and low-cost characteristics. However, when the current release coating is applied to the paper substrate of the thermal transfer label, ink or ink residue is easily present on the substrate surface after release. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a water-based release coating and a preparation method thereof. After the water-based release coating is released, no ink residue remains on the surface of the paper. Moreover, the water-based release coating does not add organic solvents, has no VOC emissions, is environmentally friendly, has low cost, and uses human-friendly raw materials, and can be applied to fields that can be contacted by the human body.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The first aspect of the present invention provides a water-based release coating, comprising the following components in percentage by mass:

[0007]

[0008]

[0009] Paraffin emulsion is an emulsion prepared from paraffin as raw material after emulsification reaction. It has the characteristics of acid and alkali resistance, hard water resistance, strong water solubility, stable emulsion, no stratification, no demulsification, no caking when diluted with water in any proportion, long shelf life, high solid content and good dispersibility. In addition, paraffin is low in price, stable in performance, high in safety, friendly to the environment and human body, and is widely used in the food field.

[0010] Palm wax emulsion is an emulsion obtained by emulsification using palm wax, a natural plant wax extracted from palm leaves. Palm wax is widely used in oral preparations, cosmetics and food fields, and has the advantages of high safety and being friendly to the human body and the environment. In addition, palm wax emulsion has the characteristics of smooth feel, good gloss, and wear resistance, and has good stability. It will not separate or break when diluted with water in any proportion.

[0011] Polyethylene wax emulsion is an emulsion prepared by emulsification reaction with polyethylene wax as raw material. It is resistant to acid, alkali and hard water, has strong water solubility and stable emulsion. It will not delaminate, break or agglomerate when diluted with water in any proportion. It has a long shelf life, high solid content and good dispersibility. In addition, polyethylene wax emulsion has excellent properties such as anti-scratch, waterproof, anti-stick and anti-fouling, wear resistance, softness and surface lubrication.

[0012] In the water-based release coating provided by the present invention, paraffin wax emulsion, palm wax emulsion and polyethylene wax emulsion are compounded and used in a certain ratio, so that thermal transfer can be better achieved.

[0013] In the water-based release coating of the present invention, the content of paraffin emulsion is 30-40%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% and the like, but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0014] In the water-based release coating of the present invention, the content of palm wax emulsion is 30-40%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% and the like, but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0015] In the water-based release coating of the present invention, the content of the polyethylene wax emulsion is 15-30%, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% and the like, but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0016] In the water-based release coating of the present invention, the release force regulator is used to regulate the release force of the water-based coating, improve the release effect, and thus help reduce ink residue on the surface of the paper. In some preferred embodiments, the release force regulator is triethanolamine monooleate.

[0017] In the water-based release coating of the present invention, the content of the release force regulator is 1-3%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0018] In the water-based release coating of the present invention, the role of the surfactant is to adjust the surface tension of the coating so as to facilitate ink printing on the release layer. In some preferred embodiments, the surfactant is an organosilicon surfactant.

[0019] In the water-based release coating of the present invention, the content of surfactant is 1-3%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0020] In the water-based release coating of the present invention, the water-based polymer resin serves to increase the fastness of the ink to the release layer and to prevent the ink from remaining on the paper substrate during release. In some preferred embodiments, the water-based polymer resin is hydroxypropyl methylcellulose.

[0021] In the water-based release coating of the present invention, the content of the water-based polymer resin is 1-3%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0022] In some preferred embodiments, the water-based release coating comprises the following components in percentage by mass:

[0023]

[0024] In a more preferred embodiment, the water-based release coating comprises the following components in percentage by mass:

[0025]

[0026]

[0027] In some preferred embodiments, the solid contents of the paraffin wax emulsion, palm wax emulsion and polyethylene wax emulsion are all 35%.

[0028] In a second aspect, the present invention further discloses a method for preparing the water-based release coating, comprising the following steps:

[0029] S1. Weigh paraffin emulsion, palm wax emulsion, polyethylene wax emulsion, surfactant, release force regulator and water-based polymer resin according to the formula;

[0030] S2. Put the formulated amounts of paraffin emulsion, palm wax emulsion, polyethylene wax emulsion, surfactant, release force regulator and water-based polymer resin into a stirring tank in sequence, and stir for 10 to 60 minutes at a temperature of 30 to 50° C. and a rotation speed of 500 to 1000 r / min to obtain the water-based release coating.

[0031] In the above step S2, the stirring temperature is preferably 30-50°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0032] In the above step S2, the stirring speed is preferably 500-1000 r / min, for example, it can be 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, 850 r / min, 900 r / min, 950 r / min, 1000 r / min, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0033] In the above step S2, the stirring time is preferably 10 to 60 minutes, for example, it can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0034] The third aspect of the present invention also provides the use of the water-based release coating in a thermal transfer label.

[0035] Furthermore, the method for applying the water-based release coating to the thermal transfer label is: coating the water-based release coating on the printing carrier, and controlling the coating thickness between 10 and 50 microns; and then baking at 100 to 150° C. for 1 to 3 minutes.

[0036] In the above method, the type of printing carrier is not limited, and can be various types of thermal transfer label substrates, including but not limited to paper substrates and polymer film substrates (such as PET). Preferably, the printing carrier is a paper substrate.

[0037] In the above method, the coating thickness is preferably 10 to 50 microns, for example, it can be 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0038] In the above method, the baking temperature is preferably 100-150°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0039] In the above method, the baking time is preferably 1 to 3 minutes, for example, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0040] In the above method, coating can be carried out by a gravure printing machine, and the coating speed is preferably 10 to 50 m / min, for example, 10 m / min, 20 m / min, 30 m / min, 40 m / min, 50 m / min, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The water-based release coating provided by the present invention selects three wax-containing emulsions, namely paraffin emulsion, palm wax emulsion and polyethylene wax emulsion, to be compounded and used in a certain proportion. These three wax-containing emulsions are not only stable in performance, highly safe, and friendly to the environment and human body, but also can better achieve thermal transfer when used in combination. In addition, a certain amount of release force regulator, surfactant and water-based polymer resin are added to the water-based release coating, which not only makes the release coating have a suitable surface tension, which is convenient for ink printing, but also helps to reduce the ink residue on the paper substrate.

[0043] 2. The water-based release coating provided by the present invention can use a paper substrate as a printing carrier, first coat a release layer on the paper substrate, then print various patterns on the release layer, then bake at high temperature to melt the wax component in the release layer, and then transfer the printed pattern to the substrate by hot pressing, thereby realizing thermal transfer of the printed pattern. The release layer has good weather resistance, chemical solvent resistance, scratch resistance, anti-sticking and anti-fouling and mechanical properties, and has broad application prospects.

[0044] 3. The water-based release coating provided by the present invention has no ink residue on the surface of the paper after release, and the water-based release coating does not add organic solvents, has no VOC emissions, is environmentally friendly, has low cost, and the raw materials are human-friendly, so it can be used in fields that can be contacted by the human body. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] This embodiment provides a water-based release coating, comprising the following components by mass percentage:

[0048]

[0049] The preparation method of the water-based release coating of this embodiment is as follows:

[0050] S1. Weigh paraffin emulsion, palm wax emulsion, polyethylene wax emulsion, triethanolamine monooleate, silicone surfactant and hydroxypropyl methylcellulose according to the formula;

[0051] S2. Put the formulated amounts of paraffin emulsion, palm wax emulsion, polyethylene wax emulsion, surfactant, release force regulator and water-based polymer resin into a stirring tank in sequence, and stir for 30 minutes at a temperature of 45°C and a rotation speed of 800r / min to obtain a water-based release coating.

[0052] The method for preparing thermal transfer label paper using the water-based release coating of this embodiment is as follows:

[0053] The water-based release agent of this embodiment is evenly coated on the wood pulp paper substrate by a three-head coating of a gravure printing machine. The coating speed is controlled at 30 m / min and the coating thickness is controlled at 30 μm. The paper is then baked at 150° C. for 3 minutes to obtain a thermal transfer label paper.

[0054] Example 2

[0055] This embodiment provides a water-based release coating, comprising the following components by mass percentage:

[0056]

[0057]

[0058] The preparation method of the water-based release coating and thermal transfer label paper of this embodiment is the same as that of Example 1.

[0059] Example 3

[0060] This embodiment provides a water-based release coating, comprising the following components by mass percentage:

[0061] The preparation method of the water-based release coating and thermal transfer label paper of this embodiment is the same as that of Example 1.

[0062] Example 4

[0063] This embodiment provides a water-based release coating, comprising the following components by mass percentage:

[0064] The preparation method of the water-based release coating and thermal transfer label paper of this embodiment is the same as that of Example 1.

[0065] Example 5

[0066] This embodiment provides a water-based release coating, comprising the following components by mass percentage:

[0067] The preparation method of the water-based release coating and thermal transfer label paper of this embodiment is the same as that of Example 1.

[0068] Comparative Example 1

[0069] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0070] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0071] Comparative Example 2

[0072] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0073]

[0074]

[0075] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0076] Comparative Example 3

[0077] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0078] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0079] Comparative Example 4

[0080] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0081]

[0082]

[0083] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0084] Comparative Example 5

[0085] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0086] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0087] Comparative Example 6

[0088] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0089] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0090] Comparative Example 7

[0091] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0092]

[0093]

[0094] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0095] Comparative Example 8

[0096] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0097] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0098] Comparative Example 9

[0099] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0100] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0101] Comparative Example 10

[0102] This comparative example provides a water-based release coating, comprising the following components by mass percentage:

[0103]

[0104] The preparation method of the water-based release coating and thermal transfer label paper in this comparative example is the same as that in Example 1.

[0105] Test Case

[0106] Take the thermal transfer label paper of Examples 1 to 5 and Comparative Examples 1 to 10, print thermal transfer ink on the release layer respectively, and bake the hot melt adhesive at 170°C for 3 minutes. Then press it on the cloth at 150°C / 6 seconds, and observe whether there is ink on the surface of the paper after release under the condition of 25°C surface temperature. Among them, the criteria for judging the residual situation are: slight residue: 1%≤residue area<5%, small amount of residue: 5%≤residue area<10%, large residue:residue area≥10%.

[0107] Table 1

[0108]

[0109]

[0110] Please refer to Table 1. After thermal transfer, the thermal transfer label papers prepared in Examples 1 to 5 have no ink residue on the surface of the paper substrate and have good thermal transfer effects.

[0111] In Comparative Examples 1 to 3, when the ratio of the three emulsions used in the water-based release coating, namely paraffin emulsion, palm wax emulsion and polyethylene wax emulsion, is not within the range of 30-40%, 30-40% and 20-30%, the release performance of the water-based release coating is affected to a certain extent, and there is a slight residue on the paper substrate after transfer. In Comparative Examples 5 to 7, when only two of the paraffin emulsion, palm wax emulsion and polyethylene wax emulsion are used in combination, there is also a slight or small amount of residue on the paper substrate after the water-based release coating is transferred. This shows that when the present invention selects paraffin emulsion, palm wax emulsion and polyethylene wax emulsion to be used in combination in a certain ratio, a better transfer effect can be achieved, and there is almost no ink residue on the paper substrate after release.

[0112] In Comparative Example 4, when polytetrafluoroethylene emulsion is used instead of polyethylene wax emulsion, the obtained water-based release coating also has a slight residue on the paper substrate after transfer.

[0113] In Comparative Example 8, no triethanolamine monooleate was added to the water-based release coating, no hydroxypropyl methylcellulose was added to the water-based release coating of Comparative Example 9, and no triethanolamine monooleate and hydroxypropyl methylcellulose were added to the water-based release coating of Comparative Example 10. From the results, the transfer effect of the thermal transfer label was not good, and there was a lot of ink residue on the paper substrate. This is because triethanolamine monooleate can adjust the release force of the water-based coating, and hydroxypropyl methylcellulose can increase the fastness of the ink to the release layer. The addition of these two ingredients can improve the release effect and reduce the ink residue on the paper surface.

[0114] In summary, the water-based release coating provided by the present invention has no ink residue on the surface of the paper after release, and the water-based release coating does not add organic solvents, has no VOC emissions, is environmentally friendly, has low cost, and the raw materials are human-friendly, so it can be used in fields that can be contacted by the human body.

[0115] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A water-based release coating, characterized in that: Includes the following components by mass percentage: Paraffin emulsion 30~40%, Palm wax emulsion 30~40%, Polyethylene wax emulsion 15~30%, Release force regulator 1~3%, Surfactant 1~3%, Water-based polymer resin 1~3%; Wherein, the release force regulator is triethanolamine monooleate, the surfactant is an organic silicon surfactant, and the water-based polymer resin is hydroxypropyl methylcellulose.

2. A water-based release coating according to claim 1, characterized in that: Includes the following components by mass percentage: Paraffin emulsion 32~40%, Palm wax emulsion 32~40%, Polyethylene wax emulsion 20~30%, Triethanolamine monooleate 2~3%, Silicone surfactant 1~2%, Hydroxypropyl methylcellulose 1~2%.

3. A water-based release coating according to claim 1, characterized in that: Includes the following components by mass percentage: Paraffin emulsion 40%, Palm wax emulsion 35%, Polyethylene wax emulsion 20%, Triethanolamine monooleate 2%, Silicone surfactant 2%, Hydroxypropyl methylcellulose 1%.

4. A water-based release coating according to claim 1, characterized in that: The solid contents of the paraffin wax emulsion, palm wax emulsion and polyethylene wax emulsion are all 35%.

5. The method for preparing a water-based release coating according to claim 1, characterized in that: The following steps are involved: According to the formula, paraffin wax emulsion, palm wax emulsion, polyethylene wax emulsion, surfactant, release force regulator and water-based polymer resin are weighed respectively; The paraffin emulsion, palm wax emulsion, polyethylene wax emulsion, surfactant, release force regulator and water-based polymer resin in the formulated amount are sequentially put into a stirring tank, and stirred for 10 to 60 minutes at a temperature of 30 to 50° C. and a rotation speed of 500 to 1000 r / min to obtain the water-based release coating.

6. Use of the water-based release coating according to any one of claims 1 to 4 in a thermal transfer label.

7. The use according to claim 6, characterized in that: The application method is: coating the water-based release coating on a printing carrier, with the coating thickness controlled between 10 and 50 microns; and then baking at 100 to 150° C. for 1 to 3 minutes; Wherein, the printing carrier is a paper substrate.

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