Solvent-free EB curing surface coating of bubble cap cover film and preparation method of solvent-free EB curing surface coating

Abstract

The invention discloses a solvent-free EB cured surface coating of a bubble cap cover film and a preparation method of the solvent-free EB cured surface coating. Polyester acrylate is selected as matrix resin and matched with adhesion promoting resin with large molecular weight and small curing shrinkage to achieve good adhesion and scratch resistance and chemical resistance; according to the coating, EB is adopted to be cured into a coating to replace film covering protection ink, the technical process is green and environmentally friendly, and the product has the excellent performance of being high in adhesive force, resistant to scraping, low in odor, good in heat sealing performance, resistant to aging, resistant to corrosion and the like. Compared with a common UV curing coating, the EB curing coating has the advantages that a photoinitiator and a solvent are not added in a product system, small molecule residues such as benzophenone and benzaldehyde do not exist, the coating is safer and more environmentally friendly, and meanwhile, EB curing is more complete, the conversion rate of monomer and oligomer double bonds is higher, and the odor is lower.

Description

Technical Field

[0001] The invention relates to the technical field of polymer coatings, and in particular to a solvent-free EB-cured surface coating of a blister cover film and a preparation method thereof. Background Art

[0002] Blister packaging is a packaging method in which the product is sealed between a blister formed by a transparent plastic sheet and a substrate. It is mainly used for the packaging of medicines, food, cosmetics and other consumer goods. The main function of blister packaging is to provide a good seal for the contents, and it also gives them higher portability and convenience of use.

[0003] Blister cover film composite film technology is developing towards high barrier properties, lightweight construction, and environmental friendliness, with applications primarily focused on pharmaceutical, food, and cosmetic packaging. A typical composite film utilizes a three-layer structure: a support layer, an aluminum foil barrier layer, and a heat-seal layer. The support layer is typically BOPA or BOPET, providing impact resistance and smoothness; the aluminum foil layer primarily provides a barrier to oxygen and moisture; and the heat-seal layer is typically made of PE or modified PVC. Blisters are primarily formed by heat-sealing a cover film and a forming film. The cover film composition (from inside to outside) is PE-PET-AL-PET. Ink is typically printed on the outermost PET layer to impart a distinctive pattern to the cover film, and then a glue-coated film is applied to protect the ink layer.

[0004] Currently, when processing and producing blister cover film products, the above four layers of materials are first compounded in sequence, and then ink is printed on the outermost PET layer to form a semi-finished product. Finally, glue is applied to the ink surface of the semi-finished product to protect the ink. Because the laminating glue contains a large amount of solvent, a large amount of VOC is generated during the drying process. In addition, a 48-hour or 72-hour curing process is required after lamination. The entire production cycle is long and uncontrollable. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned background technology, the present invention provides a solvent-free EB-cured surface coating for a blister cover film and a preparation method thereof. The EB-cured coating replaces the traditional laminating technology to protect the ink layer of the cover film, which can achieve continuous production and greatly shorten the entire cover film production cycle. In addition, the EB-cured coating has a fast curing speed, low odor, is green and environmentally friendly, and provides excellent scratch resistance, heat sealing, high gloss and other properties, which fully meets the requirements of cosmetic blister packaging and the development trend of composite film technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, a solvent-free EB-cured surface coating for a blister cover film is provided, comprising the following components in parts by weight:

[0008] Polyester acrylate 50-100 parts;

[0009] Adhesion promoting resin 0-20 parts;

[0010] 0-30 parts of acrylate monomer;

[0011] Additives 0-0.5 parts.

[0012] In order to further improve the performance of the coating, preferably, the following components are included in parts by weight:

[0013] Polyester acrylate 60-80 parts;

[0014] 5-15 parts adhesion promoting resin;

[0015] 10-30 parts of acrylate monomer;

[0016] Additives 0-0.5 parts.

[0017] Using the above technical solution:

[0018] The present invention develops a solvent-free EB coating specifically for the PET surface coating of the cover film. In the coating formulation, polyester acrylate is selected as the main resin, and is combined with an adhesion-promoting resin with a large molecular weight and small curing shrinkage to achieve good adhesion and scratch and chemical resistance. A low-functional acrylate monomer is selected as an active diluent to adjust the viscosity of the coating. The coating is cured into a coating using EB instead of a film protective ink, achieving a green and environmentally friendly process. The product has excellent properties such as strong adhesion, scratch resistance, low odor, good heat sealing, aging resistance, and corrosion resistance.

[0019] Compared with ordinary UV-curing coatings, this EB-curing coating does not add photoinitiators and solvents to the product system, and there is no small molecule residue such as benzophenone and benzaldehyde. The coating is safer and more environmentally friendly. At the same time, because EB curing is more complete, the double bond conversion rate of monomers and oligomers is higher, and the odor is also lower.

[0020] Furthermore, the polyester acrylate is amine-modified polyester acrylate, modified polyester acrylate, polyester acrylate, hyperbranched polyester acrylate, polyester acrylate EBECRYL571, or polyester acrylate M303.

[0021] Experiments in the present invention have shown that when polyurethane acrylate or different types of polyester acrylates are used as the main resin, polyester acrylate has better adhesion to PET than polyurethane acrylate. Low-functional polyester acrylates have slightly poor scratch resistance, while high-functional polyester acrylates have better scratch resistance.

[0022] Preferably, the polyester acrylate is polyester acrylate M303.

[0023] Because polyester acrylates contain polar groups such as ester and hydroxyl groups, and PET film molecules also contain ester and carbonyl groups, these polar groups can form hydrogen bonds or dipole-dipole interactions, enhancing the physical adsorption between the resin and the PET surface. Furthermore, polyester acrylates exhibit excellent wetting and spreading properties, which in turn enhances adhesion. M303 is a polyester acrylate that possesses these properties, resulting in excellent adhesion to the coating and excellent scratch resistance.

[0024] Furthermore, the adhesion-promoting resin is a pure acrylic resin.

[0025] For PET film, pure acrylic resin is selected as the adhesion-promoting resin because pure acrylic resin has a large molecular weight and small curing shrinkage, which effectively improves adhesion. However, since the addition of pure acrylic resin will affect the scratch resistance of the coating, the amount of pure acrylic resin is controlled within the above-mentioned specific range.

[0026] Acrylate monomers act as reactive diluents to adjust the viscosity of the coating. Therefore, it's important to select monofunctional, difunctional, or trifunctional acrylate monomers with strong diluting properties. Since acrylate monomers are small molecules, their addition level needs to be controlled. Excessive addition can result in insufficient molecular weight for the polymer formed after curing and crosslinking, leading to negative performance impacts such as insufficient coating toughness and odor from residual monomer.

[0027] Preferably, the types of acrylate monomers include monofunctional ones such as hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA), phenoxyethyl acrylate (POEA), isobornyl acrylate (IBOA), etc.; difunctional acrylates such as tripropylene glycol diacrylate (TPGDA), neopentyl glycol diacrylate (NPGDA), propoxy-modified neopentyl glycol diacrylate (NPG2POGDA), 1,6-hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), etc.; trifunctional acrylates such as trimethylolpropane triacrylate (TMPTA) and its ethoxy-modified and propoxy-modified derivatives, pentaerythritol triacrylate (PET3A), etc.

[0028] More preferably, the acrylate monomer may be a hydroxyl-containing monomer that can provide better adhesion, such as hydroxyethyl acrylate (HEA) and pentaerythritol triacrylate (PET3A).

[0029] Furthermore, the auxiliary agents include leveling agents and defoaming agents. Generally, leveling agents are required, and defoaming agents are added selectively according to actual conditions.

[0030] The main types of leveling agents are acrylic, silicone, fluorocarbon, and non-silicone leveling agents. The most commonly used ones are silicone leveling agents and acrylic leveling agents.

[0031] Furthermore, the coating thickness is ≤10 μm.

[0032] Since the present invention develops a solvent-free EB coating specifically for the PET surface coating of the cover film, EB curing is used to form a coating instead of the film protection ink. The coating thickness is relatively thin, with a maximum thickness of 10 μm, and can be completed using conventional EB curing. The problem of insufficient curing of the bottom layer will not occur. Under the condition that the coating is completely cured, the effect of the EB curing process parameters on the performance is not obvious. From the perspective of energy saving, it is finally determined that the energy of the electron beam is 100 KeV and the dose is 100 KGy-150 KGy.

[0033] A second aspect of the present invention provides a process for preparing the solvent-free EB-cured surface coating of the blister cover film, comprising the following steps:

[0034] The polyester acrylate, adhesion promoting resin, acrylate monomer and additive are stirred and mixed to obtain a coating mixture;

[0035] The PET layer of the blister cover film is printed with ink and subjected to corona or plasma treatment, and then the coating mixture is applied by five rollers and then EB cured to form a surface coating.

[0036] Specifically, a suitable water-based primer for ink and a cover film substrate with a primed surface are selected to improve the adhesion between the ink and the cover film substrate. After the ink is printed on the PET layer of the blister cover film, it is subjected to corona or plasma treatment to increase the surface polarity of the ink and enhance the adhesion between the ink and the subsequent EB coating.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] This invention discloses a novel EB-cured glossy coating for the surface of blister cover films. It uses a polyester acrylate as the primary resin, combined with an adhesion-promoting resin with a high molecular weight and low cure shrinkage to achieve excellent adhesion and scratch and chemical resistance. A low-functionality acrylate monomer is used as a reactive diluent to adjust the coating's viscosity. Electron beam curing (EB) is then used to achieve excellent adhesion, scratch resistance, environmental testing, and heat-sealing properties on PET composite films and digital ink layers. Compared to conventional UV-cured coatings, this EB-cured coating requires no added photoinitiators or solvents, and is free of small molecule residues such as benzophenone and benzaldehyde, making it safer and more environmentally friendly. Furthermore, because EB curing is more complete, the conversion rate of monomer and oligomer double bonds is higher, and the odor is lower.

[0039] EB curing is used to form a coating instead of laminating protective ink, making the process green and environmentally friendly. The product has the performance characteristics of scratch resistance, low odor, aging resistance, corrosion resistance, and high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 This is a photo of the coating formed in Example 1. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Example 1

[0044] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0045] 70 parts of polyester acrylate;

[0046] Adhesion promoting resin 10 parts;

[0047] 20 parts of acrylate monomer;

[0048] 0.2 parts of additives.

[0049] Wherein, the polyester acrylate is polyester acrylate M303, and the viscosity is 1000 cps;

[0050] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0051] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0052] The additive is leveling agent BYK3510.

[0053] The preparation process of the glossy coating is as follows:

[0054] The polyester acrylate, adhesion promoting resin, acrylate monomer and additive are stirred and mixed to obtain a coating mixture;

[0055] The PET layer of the blister cover film is printed with ink and plasma treated. The coating mixture is then applied using a five-roller coating and then EB cured (electron beam energy of 100 KeV, dose of 100 KGy) to form a surface coating with a thickness of 9 μm. Figure 1 .

[0056] Example 2

[0057] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0058] 60 parts of polyester acrylate;

[0059] Adhesion promoting resin 15 parts;

[0060] 10 parts of acrylate monomer;

[0061] 0.3 parts of additives.

[0062] Wherein, the polyester acrylate is polyester acrylate M303, and the viscosity is 1000 cps;

[0063] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0064] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA); the auxiliary agent is leveling agent BYK3510.

[0065] The preparation process of the bright coating is the same as that in Example 1.

[0066] Example 3

[0067] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight: 80 parts of polyester acrylate;

[0068] Adhesion promoting resin 5 parts;

[0069] 25 parts of acrylate monomer;

[0070] 0.1 part of additive.

[0071] Wherein, the polyester acrylate is polyester acrylate M303, and the viscosity is 1000 cps;

[0072] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0073] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA); the auxiliary agent is leveling agent BYK3510.

[0074] The preparation process of the bright coating is the same as that in Example 1.

[0075] Example 4

[0076] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight: 50 parts of polyester acrylate;

[0077] Adhesion promoting resin 20 parts;

[0078] 5 parts of acrylate monomer;

[0079] 0.5 parts of additives.

[0080] Wherein, the polyester acrylate is polyester acrylate M303, and the viscosity is 1000 cps;

[0081] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0082] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA); the auxiliary agent is leveling agent BYK3510.

[0083] The preparation process of the bright coating is the same as that in Example 1.

[0084] Example 5

[0085] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0086] 90 parts of polyester acrylate;

[0087] 3 parts adhesion promoting resin;

[0088] 30 parts of acrylate monomer;

[0089] 0.1 part of additive.

[0090] Wherein, the polyester acrylate is polyester acrylate M303, and the viscosity is 1000 cps;

[0091] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0092] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0093] The additive is leveling agent BYK3510.

[0094] The preparation process of the bright coating is the same as that in Example 1.

[0095] Example 6

[0096] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0097] 70 parts of polyester acrylate;

[0098] Adhesion promoting resin 10 parts;

[0099] 20 parts of acrylate monomer;

[0100] 0.2 parts of additives.

[0101] Among them, the polyester acrylate is a bifunctional amine-modified polyester acrylate Etercure6328 with a viscosity of 200-300 cps;

[0102] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0103] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0104] The additive is leveling agent BYK3510.

[0105] The preparation process of the bright coating is the same as that in Example 1.

[0106] Example 7

[0107] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0108] 70 parts of polyester acrylate;

[0109] Adhesion promoting resin 10 parts;

[0110] 20 parts of acrylate monomer;

[0111] 0.2 parts of additives.

[0112] Among them, the polyester acrylate is a high-functionality modified polyester acrylate Etercure6315 with a viscosity of 15000-25000cps;

[0113] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0114] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0115] The additive is leveling agent BYK3510.

[0116] The preparation process of the bright coating is the same as that in Example 1.

[0117] Example 8

[0118] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0119] 70 parts of polyester acrylate;

[0120] Adhesion promoting resin 10 parts;

[0121] 20 parts of acrylate monomer;

[0122] 0.2 parts of additives.

[0123] The polyester acrylate is tetrafunctional polyester acrylate GU9601Y with a viscosity of 150-500 cps;

[0124] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0125] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0126] The additive is leveling agent BYK3510.

[0127] The preparation process of the bright coating is the same as that in Example 1.

[0128] Example 9

[0129] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0130] 70 parts of polyester acrylate;

[0131] Adhesion promoting resin 10 parts;

[0132] 20 parts of acrylate monomer;

[0133] 0.2 parts of additives.

[0134] The polyester acrylate is a hyperbranched polyester acrylate GU9315Z with 12-15 functional groups and a viscosity of 300-700 cps; the adhesion promoting resin is a pure acrylate PP2203 with a viscosity of 1800-4200 cps;

[0135] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0136] The additive is leveling agent BYK3510.

[0137] The preparation process of the bright coating is the same as that in Example 1.

[0138] Example 10

[0139] A solvent-free EB-cured surface coating for a blister cover film comprises the following components in parts by weight:

[0140] 70 parts of polyester acrylate;

[0141] Adhesion promoting resin 10 parts;

[0142] 20 parts of acrylate monomer;

[0143] 0.2 parts of additives.

[0144] The polyester acrylate is polyurethane acrylate EBECRYL571 with a viscosity of 9000 cps;

[0145] The adhesion-promoting resin is pure acrylate PP2203 with a viscosity of 1800-4200cps;

[0146] The acrylate monomer is difunctional neopentyl glycol diacrylate (NPG2PODA);

[0147] The additive is leveling agent BYK3510.

[0148] The preparation process of the bright coating is the same as that in Example 1.

[0149] Comparative Example 1

[0150] Comparative Example 1 is a comparative test example of Example 1, which does not use polyester acrylate as the main resin, but uses polyurethane acrylate as the main resin. Specifically, it uses bifunctional polyurethane acrylate Etercure 6165 with a viscosity of 1700-4000 cps.

[0151] The coatings prepared in Examples 1-10 and Comparative Example 1 were tested for adhesion, scratch resistance, odor, hot stamping fastness (heat sealing performance), appearance and other properties.

[0152] The specific test methods for coating properties are shown in Table 1.

[0153] Table 1

[0154]

[0155] The performance test results of the coatings prepared in Examples 1-10 and Comparative Example 1 are shown in Table 2.

[0156] Table 2

[0157]

[0158]

[0159] The test results show that polyester acrylate, which is used as the main resin in the product system, has better adhesion to the PET cover film. Polyester acrylates with low functional groups have slightly poor scratch resistance, while polyester acrylates with high functional groups have better scratch resistance.

[0160] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A solvent-free EB-cured surface coating for a blister cover film, characterized in that: The composition comprises the following components in parts by weight: Polyester acrylate 50-100 parts; Adhesion promoting resin 0-20 parts; 0-30 parts of acrylate monomer; Additives 0-0.5 parts.

2. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that Polyester acrylate 60-80 parts; 5-15 parts adhesion promoting resin; 10-30 parts of acrylate monomer; Additives 0-0.5 parts.

3. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that: The polyester acrylate is amine-modified polyester acrylate, modified polyester acrylate, polyester acrylate, hyperbranched polyester acrylate, polyester acrylate EBECRYL571, and polyester acrylate M303.

4. The solvent-free EB-cured surface coating of the blister cover film according to claim 3, characterized in that The polyester acrylate is polyester acrylate M303.

5. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that: The adhesion promoting resin is a pure acrylate resin.

6. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that The acrylate monomer is hydroxyethyl acrylate, hydroxypropyl methacrylate, phenoxyethyl acrylate, isobornyl acrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, propoxy-modified neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate and its ethoxy-modified and propoxy-modified derivatives or pentaerythritol triacrylate.

7. The solvent-free EB-cured surface coating of the blister cover film according to claim 6, characterized in that The acrylate monomer is hydroxyethyl acrylate or pentaerythritol triacrylate.

8. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that The auxiliary agent includes a leveling agent and / or a defoaming agent.

9. The solvent-free EB-cured surface coating of the blister cover film according to claim 1, characterized in that: Coating thickness ≤10μm.

10. A process for preparing a solvent-free EB-cured surface coating of a blister cover film according to any one of claims 1 to 9, characterized in that: The steps include: The polyester acrylate, adhesion promoting resin, acrylate monomer and additive are stirred and mixed to obtain a coating mixture; The PET layer of the blister cover film is printed with ink, subjected to corona or plasma treatment, and then coated with a coating mixture, followed by EB curing to form a surface coating.

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