Transparent non-setting adhesive label free of residual adhesive and capable of being soaked in water

Abstract

The adhesive-residue-free transparent adhesive label capable of being soaked in water is sequentially provided with a thin film, an ink layer and an adhesive sticker from top to bottom, and the thin film is a transparent plastic thin film with the density lower than 1.0 g / cm < 3 >; a first priming coat is arranged between the thin film and the ink layer, and a second priming coat is arranged between the ink layer and the adhesive sticker; the adhesive sticker comprises acrylic ester, and the acrylic ester comprises 55%-75% of a soft monomer and 25%-45% of a hard monomer; the soft monomer is caprolactone acrylate; the photoinitiator comprises a functional monomer, a photoinitiator, tackifying resin and functional aids, and the functional aids comprise a cross-linking agent, an adhesion promoter and an antioxidant. According to the label, through organic combination of the structure and the adhesive sticker, good transparency is achieved, the label is resistant to aging, not prone to yellowing, free of adhesive residues after repeated bottle pasting and wide in temperature adaptation range, the label can be soaked in ice water and normal-temperature water for seven days or above, and the label is particularly suitable for being used as a label of cold drink products such as plastic bottled drinking water, soda water and glass bottled beer; and the classified recycling speed and quality of the PET bottle body materials can be improved.

Description

Technical Field

[0001] This invention relates to the field of labels, and in particular to a transparent self-adhesive label that leaves no residue and can be soaked in water. Background Technology

[0002] With increasing environmental awareness, the recycling and reuse of plastic bottles (especially PET bottles) has become a global focus. During the recycling process, the self-adhesive labels on the bottles are one of the main sources of pollution. Traditional self-adhesive labels are difficult to completely remove during flotation washing, leaving adhesive residue on PET fragments. This leads to a decrease in the purity of the recycled plastic, making it unsuitable for food-grade packaging and severely reducing the economic value of the recycled materials.

[0003] With the continuous upgrading of packaging design concepts, high-transparency film labels are being used more and more to achieve a "label-free" product appearance. Due to the problem of residual adhesive stains on traditional self-adhesive labels, there is an increasing demand for transparent self-adhesive labels that are removable, leave no residue, and are resistant to yellowing. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a transparent self-adhesive label that leaves no residue and is water-soluble, which has good transparency, is water-soluble, can be repeatedly applied to bottles without residue, and improves the speed and quality of PET bottle material classification and recycling.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A water-resistant, residue-free transparent self-adhesive label, characterized in that: from top to bottom, it consists of a film, an ink layer partially covering the film, and a self-adhesive layer completely covering the ink layer and the film, wherein the film has a density of less than 1.0 g / cm³. 3 A transparent plastic film; a first base coating is provided between the film and the ink layer, and a second base coating is provided between the ink layer and the self-adhesive;

[0007] The self-adhesive label comprises the following components by weight percentage:

[0008] The acrylate comprises 70% to 85%, wherein the acrylate comprises 55% to 75% soft monomers and 25% to 45% hard monomers;

[0009] The soft monomer is caprolactone acrylate;

[0010] The hard monomers include one or any combination of methyl methacrylate, styrene, vinyl acetate, isobornyl acrylate, isobornyl methacrylate, etc.

[0011] The functional monomer comprises 5% to 15%, wherein the functional monomer includes one or any combination of hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, and acrylamide;

[0012] The photoinitiator is 0.1% to 0.7%, and the photoinitiator includes one or any combination of diphenylphosphine oxide, 2-hydroxy-2-methylphenylacetone, and Omnirad 2100;

[0013] The tackifying resin is 5% to 10%, wherein the tackifying resin is one or any combination of hydrogenated C9 petroleum resin, hydrogenated rosin resin, and terpene resin.

[0014] Functional additives are present at 0.1% to 0.7%, including crosslinking agents, adhesion promoters, and antioxidants.

[0015] Preferably, the crosslinking agent is 1,6-hexanediol diacrylate, the adhesion promoter is PAM-200 or PAM-300, and the antioxidant is Irganox 245.

[0016] Preferably, the hard monomer is vinyl acetate, the functional monomer is acrylamide, and the tackifying resin is hydrogenated C9 petroleum resin.

[0017] Preferably, the thickness of the film is 40–50 μm.

[0018] Preferably, the thickness of the self-adhesive is 118–130 μm.

[0019] Preferably, the wet coating thickness of the first and second base coatings is 20–40 μm.

[0020] Preferably, the first and second base coats are two-component oil-based polyurethane coatings, wherein the polyurethane coating comprises a hydroxyl-containing polyurethane resin and an isocyanate curing agent.

[0021] Preferably, the peel force of the self-adhesive is 3-5 N / 25 mm.

[0022] Preferably, the self-adhesive label is provided with a separable protective film, and the protective film is provided with an isolation layer on the side close to the self-adhesive label.

[0023] Preferably, the film is a MOPP film.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. By rationally setting the label structure and organically combining soft monomers, hard monomers, functional monomers, and functional additives in the self-adhesive formula, the label achieves good transparency, is resistant to aging and does not easily yellow, can be repeatedly applied to bottles, leaves no residue when removed, and is suitable for a wide temperature range (-40℃~120℃). It can withstand soaking in ice water or room temperature water for more than seven days without label removal, and is especially suitable for labels of plastic bottled drinking water, soft drinks, and glass bottled beer and other cold beverage products.

[0026] 2. Using MOPP film as the base film, it has low hardness, good dimensional stability, and strong ability to adhere to curved surfaces. It can also achieve good adhesion to curved bottles even with low peel force. Through stable label adhesion and low peel force, it can further ensure that no adhesive residue is left after the label is removed.

[0027] 3. Using MOPP film as the substrate, the density difference between MOPP film and PET bottle can be used to significantly improve the speed and quality of PET bottle material sorting and recycling through flotation cleaning. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the label structure.

[0029] Among them: film 1, first base coating 2, ink layer 3, second base coating 4, self-adhesive 5, release layer 6, protective film 7. Detailed Implementation

[0030] This invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] The present invention will be further described below with reference to specific embodiments:

[0033] like Figure 1 As shown, a water-resistant, residue-free transparent self-adhesive label is configured from top to bottom as follows: a film 1, an ink layer 3 partially covering the film 1, and a self-adhesive label 5 completely covering the ink layer 3 and the film 1. The film 1 has a density of less than 1.0 g / cm³. 3 A transparent plastic film, wherein a first base coating layer 2 is provided between the film 1 and the ink layer 3, and a second base coating layer 4 is provided between the ink layer 3 and the self-adhesive 5;

[0034] The self-adhesive label 5 comprises the following components by weight percentage:

[0035] The acrylate comprises 70% to 85%, wherein the acrylate comprises 55% to 75% soft monomers and 25% to 45% hard monomers;

[0036] The soft monomer is caprolactone acrylate;

[0037] The hard monomers include one or any combination of methyl methacrylate, styrene, vinyl acetate, isobornyl acrylate, isobornyl methacrylate, etc.

[0038] Caprolactone acrylate possesses both acrylate double bonds capable of polymerization and hydroxyl groups capable of cross-linking. Cross-linking enhances the cross-linking density and hydrolysis resistance of the coating, while also providing excellent flexibility. This allows labels to adhere better to curved surfaces like bottles with low peel force.

[0039] The functional monomers are 5% to 15%, including one or any combination of hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, and acrylamide.

[0040] In this embodiment, acrylamide is selected as the functional monomer. Caprolactone acrylate and acrylamide are copolymerized through hydrogen bonding to form a high heat-resistant network, thereby improving the high and low temperature resistance of the self-adhesive.

[0041] The photoinitiator is 0.1% to 0.7%, including one or any combination of diphenylphosphine oxide, 2-hydroxy-2-methylphenylacetone, and Omnirad 2100 (a trade name for a photoinitiator manufactured by IGM).

[0042] The tackifying resin comprises 5% to 10%, wherein the tackifying resin is one or any combination thereof selected from hydrogenated C9 petroleum resin, hydrogenated rosin resin, terpene resin, etc. Hydrogenated C9 petroleum resin has good transparency and stability and is preferred.

[0043] Functional additives, 0.1% to 0.7%, including crosslinking agents, adhesion promoters, and antioxidants;

[0044] The crosslinking agent is 1,6-hexanediol diacrylate, which has good optical properties and can ensure good transparency of the self-adhesive.

[0045] The adhesion promoter is PAM-200 or PAM-300. PAM-200 and PAM-300 are trade names for Rhodia's special phosphate monomers, which improve adhesion and stability.

[0046] The antioxidant is Irganox 245, a highly effective hindered phenolic antioxidant used to prevent thermal oxidative degradation of self-adhesive labels during processing and use. It has low volatility, no odor, and excellent color stability.

[0047] By setting a first base coating 2 and a second base coating 4, the adhesion between the film 1 and the self-adhesive 5 is improved, ensuring that the peel force between the self-adhesive 5 and the film 1 after the label is applied is greater than the peel force between the self-adhesive 5 and the object being applied, thereby achieving the performance of no adhesive residue.

[0048] Furthermore, the hard monomer is vinyl acetate, the functional monomer is acrylamide, and the tackifying resin is hydrogenated C9 petroleum resin.

[0049] Furthermore, the thickness of the thin film 1 is 40–50 μm.

[0050] Furthermore, the thickness of the self-adhesive 5 is 118–130 μm.

[0051] Furthermore, the wet coating thickness of the first base coating 2 and the second base coating 4 is 20-40 μm.

[0052] Furthermore, the first base coating 2 and the second base coating 4 are two-component oil-based polyurethane coatings, wherein the polyurethane coating comprises a hydroxyl-containing polyurethane resin and an isocyanate curing agent. This coating is characterized by its transparency, resistance to yellowing, good adhesion, and excellent water resistance.

[0053] Furthermore, the peel force of the self-adhesive label 5 is 3-5 N / 25 mm. The low peel force can better achieve the performance of repeated bottle application without residue.

[0054] The peel strength test method is in accordance with GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes".

[0055] Furthermore, in order to protect the self-adhesive from getting dirty during storage and application, a separable protective film 7 is provided on the self-adhesive 5, and an isolation layer 6 is provided on the side of the protective film 7 close to the self-adhesive 5.

[0056] Furthermore, the film 1 is a MOPP film.

[0057] MOPP film (uniaxially oriented polypropylene film) has low hardness, good dimensional stability and gas barrier properties, and strong ability to adhere to curved surfaces. Even with low peel force (3-5 N / 25 mm), it exhibits excellent adhesion when applied to curved bottles. This embodiment achieves an excellent balance of low peel force, high adhesion, and water resistance by combining MOPP with caprolactone soft monomers.

[0058] Due to the lower surface tension of MOPP film, the adhesion of self-adhesive labels is relatively poor. Therefore, using the stable MOPP film to prepare transparent self-adhesive labels is more challenging than using the commonly used PETG film, making it more difficult to achieve residue-free label production. The difference in surface energy between PETG and MOPP leads to different requirements for self-adhesive materials, making them incompatible.

[0059] To address this issue, the film 1 in this embodiment undergoes corona treatment on the adhesive surface before being applied to the machine, followed by the application of a first base coating 2 to enhance its adhesion to the self-adhesive 5. Simultaneously, combined with the self-adhesive formulation of this invention, it further improves the effect of label removal and residue-free repeated bottle application.

[0060] The label prepared in this embodiment can be repeatedly applied to bottles without leaving any residue, has good transparency, and when it is soaked in a hot alkaline water bath at 85°C for label removal and recycling, the alkali-responsive functional groups in the self-adhesive 5 undergo a chemical change with the alkaline water, resulting in the loss of intermolecular forces, and the self-adhesive 5 completely loses its adhesiveness, allowing the label to completely detach from the attached bottle.

[0061] Then, the density difference between MOPP and PET was used for flotation washing and classification, with PET flakes having a density greater than 1 g / cm³. 3 It will sink to the bottom of the water, while the density of the MOPP label and bottle cap is less than 1g / cm³. 3 The labels float on the water surface and are removed as impurities, thus separating and recycling the labels from the PET bottles. This avoids the problem of micro-adhesive residue and significantly improves the speed and quality of material sorting and recycling. Tests show that the label removal rate in this embodiment exceeds 99.98%, and the impurity content of the recycled PET is below 300 ppm, far exceeding food-grade standards (<600 ppm), greatly enhancing the economic value of the recycled materials.

[0062] The label prepared in this embodiment has good transparency, can be repeatedly applied to bottles, and leaves no adhesive residue after removal. The label is adaptable to a wide temperature and humidity range (-40℃ to 120℃) and can remain on the label for more than seven days when soaked in ice water or room temperature water. It is particularly suitable for labels of cold beverage products such as plastic bottled drinking water, soft drinks, and glass bottled beer. Moreover, it is extremely convenient and environmentally friendly to recycle.

[0063] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A water-resistant, residue-free, transparent self-adhesive label, characterized in that: The components are arranged from top to bottom as follows: a film (1), an ink layer (3) partially covering the film (1), and an adhesive layer (5) completely covering the ink layer (3) and the film (1). The film (1) has a density of less than 1.0 g / cm³. 3 A transparent plastic film; a first base coating layer (2) is provided between the film (1) and the ink layer (3), and a second base coating layer (4) is provided between the ink layer (3) and the self-adhesive (5); The self-adhesive label (5) comprises the following components by weight percentage: The acrylate comprises 70%–85%, wherein the acrylate comprises 55%–75% soft monomers and 25%–45% hard monomers; the soft monomers are caprolactone; the hard monomers include one or any combination of methyl methacrylate, styrene, vinyl acetate, isobornyl acrylate, and isobornyl methacrylate. The functional monomer comprises 5% to 15%, wherein the functional monomer includes one or any combination of hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, and acrylamide; The photoinitiator is 0.1% to 0.7%, and the photoinitiator includes diphenylphosphine oxide. 2-Hydroxy-2-methylphenylacetone, Omnirad 2100, or any combination thereof; The tackifying resin is 5% to 10%, wherein the tackifying resin is one or any combination of hydrogenated C9 petroleum resin, hydrogenated rosin resin, and terpene resin. Functional additives are present at 0.1% to 0.7%, including crosslinking agents, adhesion promoters, and antioxidants.

2. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The crosslinking agent is 1,6-hexanediol diacrylate, the adhesion promoter is PAM-200 or PAM-300, and the antioxidant is Irganox 245.

3. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The hard monomer is vinyl acetate, the functional monomer is acrylamide, and the tackifying resin is hydrogenated C9 petroleum resin.

4. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The thickness of the film (1) is 40-50 μm.

5. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The thickness of the self-adhesive (5) is 118-130 μm.

6. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The wet coating thickness of the first base coating (2) and the second base coating (4) is 20-40 μm.

7. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The first base coating (2) and the second base coating (4) are two-component oil-based polyurethane coatings, wherein the polyurethane coatings include a hydroxyl-containing polyurethane resin and an isocyanate curing agent.

8. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The peel force of the self-adhesive (5) is 3-5 N / 25 mm.

9. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The self-adhesive label (5) is provided with a separable protective film (7), and an isolation layer (6) is provided on the side of the protective film (7) close to the self-adhesive label (5).

10. The water-resistant, residue-free, self-adhesive label as described in claim 1, characterized in that: The film (1) is a MOPP film.

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