Plastic-based braille ink, matched bottom coating liquid and preparation method of plastic coin braille presswork

Abstract

The invention discloses plastic-based braille ink, a matched prime coat liquid and a preparation method of a plastic coin braille printed matter. The plastic-based braille ink is prepared from 10 to 40 parts of blocked isocyanate terminated polyurethane acrylate, 10 to 40 parts of a reactive diluent 1, 20 to 50 parts of a reactive diluent 2, 10 to 20 parts of a photoinitiator and 1 to 5 parts of an auxiliary agent. The matched prime coat liquid is prepared from 10 to 80 parts of blocked isocyanate, 1 to 10 parts of silane coupling agent and the balance of water. The plastic-based braille presswork prepared by the invention can be printed and formed at one time to realize the braille height of more than 200 microns, and is high in stacking efficiency, high in adhesive force on a plastic base material and good in touch feeling.

Description

Technical Field

[0001] The invention relates to the technical field of braille printing, and is a method for preparing a plastic-based braille ink and a matching primer liquid and a plastic coin braille print. Background Art

[0002] Plastic-based banknotes have become the mainstream direction of coinage technology development due to their special materials, high printing difficulty, high anti-counterfeiting technology, and long service life. At present, plastic banknotes such as the Australian dollar, Canadian dollar, and British pound are all printed with Braille. They use special composite substrates and embossing technology to press Braille on plastic banknotes. The prepared Braille convex points are higher than deep intaglio printed Braille, not easy to collapse, and have strong recognition. However, its process is complicated, requires special templates, and is costly.

[0003] Conventional plastic substrates have no polar groups on their surfaces, so it is difficult to chemically bond with ink and their adhesion is poor. In particular, banknotes require materials to be resistant to solvents, rubs, and washes, and have a long service life, which places extremely high demands on ink materials.

[0004] Publication No. CN101665024A discloses an inkjet printing device and method that can be used for Braille, embossed printing and conventional printing applications. The radiation-curable ink is deposited on the substrate in multiple layers by the inkjet print head to form the height of the Braille, but each printing can only form a height of 5-15 microns. Printing 300 microns requires 20-60 layers, which is very slow. Conventional radiation-curable inks have poor adhesion to plastic substrates.

[0005] CN106671630A discloses a method for printing raised Braille dots. The method increases the thickness of the screen printing screen from 18 microns to 250-350 microns, and can print a Braille height of 250-300 microns at one time. However, this method requires coating the entire plate first and then exposing it to remove the non-image area. Each time the Braille typesetting is changed, the plate must be re-made. The platemaking method is complicated, subtractive manufacturing wastes materials, the price is high, and it is difficult to ensure that there is no ink residue in the mesh holes with high thickness, resulting in uneven ink dots and inconsistent heights.

[0006] CN108569059B discloses a Braille print and a preparation method thereof, wherein a light-curing or heat-curing ink is printed on a hydrophobic substrate, and the Braille dots are de-wetted to achieve a larger height-to-diameter ratio, thereby reducing the number of prints. However, the ink has no chemical bond with the hydrophobic substrate, and the adhesion is poor.

[0007] In summary, the prior art has problems such as complex process, low stacking efficiency, poor uniformity, and poor adhesion on plastic substrates when preparing Braille. Summary of the invention

[0008] The purpose of the present invention is to solve the problems of low stacking efficiency, poor uniformity of Braille dot height and poor adhesion of ink on plastic substrates in plastic-based Braille printing.

[0009] A first aspect of the present invention provides a plastic-based Braille ink and a matching primer liquid thereof.

[0010] The plastic-based Braille ink is composed of 10-40 parts of blocked isocyanate-terminated polyurethane acrylate, 10-40 parts of reactive diluent 1, 20-50 parts of reactive diluent 2, 10-20 parts of photoinitiator, and 1-5 parts of auxiliary agent;

[0011] The matching primer solution is composed of 10-80 parts of blocked isocyanate, 1-10 parts of silane coupling agent and the balance of water.

[0012] A second aspect of the present invention provides a method for preparing a plastic-based Braille printed product.

[0013] 1) Apply the matching primer liquid to the plastic substrate, heat and cure at 60-120°C to form a primer layer;

[0014] 2) using an inkjet printer to print the plastic-based Braille ink on the base coating according to a predetermined pattern, and obtaining the Braille characters or patterns after light curing;

[0015] 3) Curing the light-cured Braille characters or patterns at 50-100° C. and 50-80% humidity for 10-30 minutes to obtain the plastic coin Braille print.

[0016] Beneficial effects of the present invention:

[0017] The plastic-based Braille printed product prepared by the present invention can be printed and formed at one time to achieve a Braille height of more than 200 microns, has high stacking efficiency, high adhesion on the plastic substrate, and good touch. DETAILED DESCRIPTION

[0018] A first aspect of the present invention provides a plastic-based Braille ink and a matching primer liquid thereof.

[0019] The plastic-based Braille ink is composed of 10-40 parts of blocked isocyanate-terminated polyurethane acrylate, 10-40 parts of reactive diluent 1, 20-50 parts of reactive diluent 2, 10-20 parts of photoinitiator, and 1-5 parts of auxiliary agent;

[0020] The elongation at break of the blocked isocyanate-terminated polyurethane acrylate is 200%-500%.

[0021] The elongation at break of blocked isocyanate-terminated polyurethane acrylate is too low, the expansion height is insufficient, the elongation at break is too high, the surface curing is poor, the system is sticky, and the use is affected.

[0022] The molar content of isocyanate groups in the blocked isocyanate-terminated polyurethane acrylate is 10-30%.

[0023] The reactive diluent 1 contains a hydroxyl group or an amino group and is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, acryloylmorpholine, N-vinylcaprolactam, and vinyl pyrrolidone.

[0024] The volume shrinkage rate of the reactive diluent 2 is greater than 10, and the reactive diluent 2 is selected from one or more of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and ethoxylated trimethylolpropane triacrylate.

[0025] The photoinitiator is selected from one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-isopropylthioxanthone, benzophenone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, phenylbis-2,4,6-trimethylbenzoylphosphine oxide, and ethyl p-dimethylaminobenzoate.

[0026] When the photoinitiator content is 10-20%, the reaction rate can be greatly increased, the cohesion of the system after curing can be increased, which is conducive to the volume shrinkage and height increase of the ink after curing. If the initiator content is too little, the cohesion is insufficient and the height of the Braille dots is too low. If the initiator content is too much, there will be too many residual products in the system and the ink layer will become brittle.

[0027] The auxiliary agent is an organic silicon leveling agent and a polymerization inhibitor, for example, BYK-333 and BYK-3500 of BYK Chemicals, Chiguard100 and Chiguard101 of ChiTi Chemicals, etc.

[0028] The plastic-based Braille ink has a viscosity of 3-20 mpas at 25°C.

[0029] The matching primer solution is composed of 10-80 parts of blocked isocyanate, 1-10 parts of silane coupling agent and the balance of water.

[0030] The molar content of isocyanate groups in the blocked isocyanate is 10-30%.

[0031] The silane coupling agent is selected from conventional silane coupling agents, such as KH550, KH560 and the like.

[0032] A second aspect of the present invention provides a method for preparing a plastic-based Braille printed product.

[0033] 1) Apply the matching primer liquid to the plastic substrate, heat and cure at 60-120°C to form a primer layer;

[0034] 2) Using an inkjet printer to print the plastic coin Braille ink on the base coating according to a predetermined pattern, and then photocuring to obtain the Braille characters or patterns;

[0035] 3) Curing the light-cured Braille characters or patterns at 50-100° C. and 50-80% humidity for 10-30 minutes to obtain a plastic coin Braille sample.

[0036] The surface energy of the matching primer after curing is 26-30mN / m;

[0037] The height of the braille characters is 200-500 microns.

[0038] The peel strength of the braille and plastic-based braille ink is greater than 50N;

[0039] The inkjet printer is a common commercially available industrial printer, for example, an industrial-grade 9060UV printer from Rucai Printing Equipment Co., Ltd.

[0040] The coating method can be conventional rolling coating, spraying, anilox roller coating and the like.

[0041] The matching primer has a very low surface energy after curing, and the volume of the ink shrinks when it cures. At this time, the three-phase line of the ink can be driven to shrink and move together to form a spherical shape, achieving a large height-to-diameter ratio. At 50-100°C, the blocked isocyanate end is unblocked, and a part of the isocyanate group and the hydroxyl or amino group of the active diluent 1 undergo a cross-linking reaction, and are connected to the plastic-based Braille ink through hydrogen bonds, greatly improving the adhesion; the other part of the isocyanate group reacts with water in moisture to generate carbon dioxide, causing the volume of the Braille dots to expand. Due to the ultra-long elongation of polyurethane acrylate, the height of the Braille dots can be expanded to 200-400 microns.

[0042] The plastic-based Braille print prepared by the present invention has high adhesion and a peel strength greater than 50N because the base coating layer and the ink layer are bonded when solidified. Volume contraction occurs during light solidification and volume expansion occurs during heat solidification. Under the dual effects, the Braille characters can be printed at a height of 200-500 microns in one go, which greatly improves the printing speed and saves costs. When the generated carbon dioxide evaporates, a layer of frosted touch is formed on the surface of the Braille characters, making the Braille characters easier to identify. The high-elongation polyurethane acrylate system makes the Braille characters more elastic and greatly improves the comfort.

[0043] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0044] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0045] Example 1

[0046] 30 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 280% and an isocyanate group molar content of 15%), 25 parts of hydroxypropyl acrylate, 30 parts of dipropylene glycol diacrylate, 13 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide and 2 parts of BYK-333 were stirred and mixed to make a plastic coin ink with a viscosity of 13 mpas.

[0047] 60 parts of blocked isocyanate (isocyanate molar content of 15%), 5 parts of KH550 and 35 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0048] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0049] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 80°C and 60% humidity for 15 minutes to obtain a plastic coin Braille sample A1. Its basic properties are shown in Table 1.

[0050] Example 2

[0051] 15 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 350% and an isocyanate group molar content of 20%), 30 parts of acryloylmorpholine, 37 parts of 1,6-hexanediol diacrylate, 15 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide and 2 parts of BYK-3500 were stirred and mixed evenly to prepare a plastic coin ink with a viscosity of 5 mpas.

[0052] 40 parts of blocked isocyanate (isocyanate molar content is 25%), 8 parts of KH560 and 52 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0053] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0054] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 80°C and 70% humidity for 20 minutes to obtain a plastic coin Braille sample A2. Its basic properties are shown in Table 1.

[0055] Example 3

[0056] 25 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 300% and an isocyanate group molar content of 18%), 25 parts of N-vinyl caprolactam, 30 parts of trimethylolpropane triacrylate, 8 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, 8-isopropylthioxanthone and 4 parts of BYK-333 were stirred and mixed to make a plastic coin ink with a viscosity of 14 mpas.

[0057] 50 parts of blocked isocyanate (isocyanate molar content is 20%), 5 parts of KH560 and 45 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0058] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0059] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 80°C and 70% humidity for 20 minutes to obtain a plastic coin Braille sample A3. Its basic properties are shown in Table 1.

[0060] Example 4

[0061] 20 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 400% and an isocyanate group molar content of 25%), 15 parts of acryloylmorpholine, 15 parts of hydroxybutyl acrylate, 12 parts of 1,6-hexanediol diacrylate, 20 parts of dipropylene glycol diacrylate, 16 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, 1 part of Chiguard101 and 1 part of BYK-3500 were stirred and mixed to make a plastic coin ink with a viscosity of 5 mpas.

[0062] 60 parts of blocked isocyanate (isocyanate molar content of 15%), 8 parts of KH550 and 32 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0063] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0064] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 90°C and 70% humidity for 10 minutes to obtain a plastic coin Braille sample A4. Its basic properties are shown in Table 1.

[0065] Example 5

[0066] 10 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 280% and an isocyanate group molar content of 15%), 35 parts of hydroxypropyl acrylate, 30 parts of dipropylene glycol diacrylate, 13 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide and 2 parts of BYK-333 were stirred and mixed to make a plastic coin ink with a viscosity of 10 mpas.

[0067] 60 parts of blocked isocyanate (isocyanate molar content of 15%), 5 parts of KH550 and 35 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0068] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0069] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 80°C and 60% humidity for 15 minutes to obtain a plastic coin Braille sample A5. Its basic properties are shown in Table 1.

[0070] Example 6

[0071] 40 parts of isocyanate-terminated polyurethane acrylate (purchased from Sartomer, with an elongation at break of 280% and an isocyanate group molar content of 15%), 15 parts of hydroxypropyl acrylate, 30 parts of dipropylene glycol diacrylate, 13 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide and 2 parts of BYK-333 were stirred and mixed to make a plastic coin ink with a viscosity of 20 mpas.

[0072] 60 parts of blocked isocyanate (isocyanate molar content of 15%), 5 parts of KH550 and 35 parts of water were stirred and mixed uniformly to prepare a primer solution.

[0073] The primer liquid was applied onto the plastic substrate and heated and cured at 80° C. to prepare a primer layer.

[0074] The plastic coin ink was printed on a plastic substrate coated with a primer by an inkjet printer and cured by UV light. The light-cured Braille characters or patterns were cured at 80°C and 60% humidity for 15 minutes to obtain a plastic coin Braille sample A6. Its basic properties are shown in Table 1.

[0075] Example 7

[0076] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate elongation at break of the isocyanate-terminated polyurethane acrylate was 200%, and a plastic coin Braille sample A7 was obtained. Its basic properties are shown in Table 1.

[0077] Example 8

[0078] The plastic coin ink and primer were prepared according to Example 1, except that the elongation at break of the isocyanate-terminated polyurethane acrylate was 500%, and a plastic coin Braille sample A8 was obtained. Its basic properties are shown in Table 1.

[0079] Example 9

[0080] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate content of the isocyanate-terminated polyurethane acrylate was 10%, and a plastic coin Braille sample A9 was obtained. Its basic properties are shown in Table 1.

[0081] Example 10

[0082] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate content of the isocyanate-terminated polyurethane acrylate was 30%, and a plastic coin Braille sample A10 was obtained. Its basic properties are shown in Table 1.

[0083] Embodiment 11

[0084] Plastic coin ink and primer were prepared according to Example 1, except that the content of isocyanate-terminated polyurethane acrylate was 33 parts and the content of photoinitiator was 10 parts, to obtain plastic coin Braille sample A11. Its basic properties are shown in Table 1.

[0085] Example 12

[0086] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate content of the isocyanate-terminated polyurethane acrylate was 5%, to obtain a plastic coin Braille sample A12. The basic properties of the sample are shown in Table 1.

[0087] Embodiment 13

[0088] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate content of the isocyanate-terminated polyurethane acrylate was 50%, to obtain a plastic coin Braille sample A13. The basic properties of the sample are shown in Table 1.

[0089] Embodiment 14

[0090] The plastic coin ink and primer were prepared according to Example 1, except that the elongation at break of the isocyanate-terminated polyurethane acrylate was 100%, and a plastic coin Braille sample A14 was obtained. Its basic properties are shown in Table 1.

[0091] Comparative Example 1

[0092] The plastic coin ink and primer were prepared according to Example 1, except that the polyurethane acrylate (purchased from Sartomer) did not contain an isocyanate group, and the obtained plastic coin Braille sample A15 had its basic properties shown in Table 1.

[0093] Comparative Example 2

[0094] The plastic coin ink and primer were prepared according to Example 1, except that the isocyanate-terminated polyurethane acrylate was 5 parts, and the obtained plastic coin Braille sample A16 had its basic properties shown in Table 1.

[0095] Comparative Example 3

[0096] The plastic coin ink and primer were prepared according to Example 1, except that the photoinitiator was 5 parts, and the obtained plastic coin Braille sample A17 had its basic properties shown in Table 1.

[0097] Comparative Example 4

[0098] The plastic coin ink and primer were prepared according to Example 1, except that the blocked isocyanate was 5 parts, and the obtained plastic coin Braille sample A18 had its basic properties shown in Table 1.

[0099] Test Case

[0100] (1) Surface energy

[0101] Testing equipment: KRUSS portable contact angle meter, model: MSA.

[0102] (2) Braille height

[0103] Test equipment: Micrometer screw

[0104] (3) Peel strength

[0105] Test standard: GB / T2791-1995

[0106] Table 1

[0107]

[0108]

[0109] It can be seen from the data in Table 1 that the surface of the plastic coin Braille ink of the present application is low after curing, and the height of the prepared plastic coin Braille print is above 200 microns, and even more than 400 microns. The peel strength is very high, even reaching more than 70N.

[0110] Among them, according to the comparison between Example 1 and Comparative Example 1, it can be found that when the prepolymer used in the composition is a blocked isocyanate-terminated polyurethane acrylate, the height of the Braille dots and the peel strength can be significantly improved;

[0111] According to the comparison between Example 1, Example 9, Example 10 and Example 12, it can be found that the isocyanate group of the blocked isocyanate-terminated polyurethane acrylate also has a great influence on the height and adhesion of the Braille dots. When the content of the isocyanate group is small (such as 5% in Example 12), the improvement effect on the height and adhesion of the Braille is not obvious. As the isocyanate group content increases to 40%, the height and adhesion of the Braille are significantly improved. However, if the isocyanate group content continues to increase to 50%, due to the large amount of isocyanate free groups remaining in the system, its adhesion is affected instead, and the peel strength drops to 50N.

[0112] According to the comparison between Example 1, Example 11 and Comparative Example 3, it can be found that the photoinitiator content also has a great influence on the height and adhesion of the Braille dots. When the initiator content is reduced, the cohesion is insufficient, the height of the Braille dots is too low, the crosslinking density of the system is low, and the adhesion is poor.

[0113] According to the comparison between Example 1 and Comparative Example 4, it can be found that the content of blocked isocyanate is too small, the reaction with hydroxyl group is too little, the adhesion is poor, and the Braille height is small.

[0114] The above is an exemplary description of the embodiments of the present invention. However, the protection scope of the present invention is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A plastic-based Braille ink and its matching primer, characterized in that: The plastic-based Braille ink is composed of 10-40 parts of blocked isocyanate-terminated polyurethane acrylate, 10-40 parts of active diluent 1, 20-50 parts of active diluent 2, 10-20 parts of photoinitiator, and 1-5 parts of auxiliary agent; the matching primer is composed of 10-80 parts of blocked isocyanate, 1-10 parts of silane coupling agent and the balance of water.

2. The plastic-based Braille ink and its matching primer according to claim 1, characterized in that: The elongation at break of the blocked isocyanate-terminated polyurethane acrylate is 200%-500%.

3. The plastic-based Braille ink and its matching primer according to claim 1, characterized in that: The molar content of isocyanate groups in the blocked isocyanate-terminated polyurethane acrylate is 10-30%.

4. The plastic-based Braille ink and its matching primer according to claim 1, characterized in that: The reactive diluent 1 contains a hydroxyl group or an amino group and is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, acryloylmorpholine, N-vinylcaprolactam, and vinyl pyrrolidone.

5. The plastic-based Braille ink and its matching primer according to claim 1, characterized in that: The volume shrinkage rate of the reactive diluent 2 is greater than 10, and the reactive diluent 2 is selected from one or more of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and ethoxylated trimethylolpropane triacrylate.

6. The plastic-based Braille ink and its matching primer according to claim 1, characterized in that: The molar content of isocyanate groups in the blocked isocyanate is 10-30%.

7. The plastic-based Braille ink and its matching primer according to any one of claims 1 to 6, characterized in that: The plastic-based Braille ink has a viscosity of 3-20 mpas at 25°C.

8. A method for preparing a plastic-based Braille printed product, characterized in that: 1) applying the primer solution of any one of claims 1 to 7 onto a plastic substrate, and heating and curing at 60-120° C. to form a primer layer; 2) using an inkjet printer to inkjet print the plastic-based Braille ink according to any one of claims 1 to 7 on the base coating in a predetermined pattern, and obtaining Braille characters or patterns after photocuring; 3) Curing the light-cured Braille characters or patterns at 50-100° C. and 50-80% humidity for 10-30 minutes to obtain a plastic coin Braille print.

9. A method for preparing a plastic-based Braille printed matter according to claim 8, characterized in that: The surface energy of the matching primer liquid after curing is 26-30 mN / m.

10. The plastic-based Braille printed product according to claim 8, characterized in that: The height of the Braille characters is 200-500 microns; The peel strength of the Braille characters and the plastic-based Braille ink is greater than 50N.

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