Cationic coating digital ink-jet printing pretreatment liquid as well as preparation method and application thereof

Abstract

The invention discloses a cationic coating digital ink-jet printing pretreatment liquid and a preparation method and application thereof, and the preparation method comprises the following steps: in the presence of a chain transfer agent, copolymerizing a cationic monomer and a water-soluble nonionic monomer to obtain the cationic coating printing pretreatment liquid; the pretreatment liquid is finished on the fabric, the pretreatment liquid and electronegative coating particles printed on the fabric through jet printing form electrostatic attraction through the cationic property of the pretreatment liquid, the electronegative coating particles are deposited on the surface of the fabric, permeation is avoided, and the apparent color yield of the fabric is improved; meanwhile, as the electrostatic adsorption efficiency is high, the slurry amount for pretreatment is reduced, the influence of the slurry on the hand feeling of the fabric is small, and the hand feeling of the jet-printed fabric is improved. Besides, benefited from the control of the chain transfer agent and the copolymerization of the hydrophilic monomer, the resin in the pretreatment liquid is low in molecular weight, high in water solubility and easy to wash away, and the staining resistance of the pigment printed fabric is also improved when the pigment printed fabric is worn and washed with water.

Description

Technical Field

[0001] The invention relates to the field of textile auxiliaries, and in particular to a cationic coating digital printing pretreatment liquid designed based on hydrophilicity and molecular weight, a preparation method thereof, and application of the pretreatment liquid on fabrics. Background Art

[0002] Before digital printing of paint, the refined fabric needs to be treated with a pre-treatment agent to inhibit the penetration of inkjet droplets and achieve the process requirements of clear outline of printed patterns, pure pattern colors and ground colors. In addition, unlike the digital printing processes of reactive, acidic and disperse dyes, the digital printing process of paint does not require water washing. If sodium alginate, modified cellulose, modified starch, and acrylate synthetic thickeners commonly used in reactive, acidic and disperse dye printing are used as pre-treatment agents, these pre-treatment agents cannot be removed and will remain on the digital printing fabric of paint, which will inevitably make the fabric feel hard. Therefore, the performance of the pre-treatment agent is crucial to the effect of digital printing of paint.

[0003] Kim et al. (Kim HJ, Hong JP, Kim MJ, et al. Improving the digital to garment inkjet printing properties of cotton by controlling the butyl acrylate content of the surface treatment agent [J]. Applied Surface Science, 2022, 583: 152322.) used emulsion polymerization to adjust the copolymerization ratio of butyl acrylate (BA, soft segment) and vinyl acetate (VA, rigid segment), thereby improving the film-forming property of the copolymer, adhering the colorant to the fabric surface, and improving the color strength and wet friction fastness of the printed cotton fabric. However, because the Zeta potential of the resin particles in the pretreatment liquid is about -47mV, which is negatively charged, there is no strong electrostatic attraction between the negatively charged colorants. The principle of the pretreatment liquid to prevent infiltration is to form a film through the resin, inhibit the ink from infiltrating along the capillaries between the fibers, and improve the clarity of the printing. However, the pretreatment liquid based on this principle has a high dosage and low efficiency, and the printed fabric often has a poor feel. Recently, patent CN115636907 A disclosed a fabric coating digital printing pretreatment agent containing cationic polymers, a preparation method and its application, and reported its application in coating digital printing of polyester-cotton blended fabrics. The principle is as follows: the impregnated cationic compound makes the fiber surface positively charged; first, it promotes the precipitation of negatively charged coating particles from the ink and makes it impossible to migrate with the water phase; second, the affinity between the fiber and the negatively charged coating ink is enhanced, and the migration ability is weakened; the two work together to inhibit the penetration of coating particles into the fabric, and obtain an ideal coating digital printing effect. Compared with the highly hygroscopic sodium alginate, modified cellulose, modified starch and other pretreatment liquids used in active, acidic and disperse dye printing, the pretreatment agent containing cationic polymers is more efficient and can inhibit penetration at a lower dosage, so it has little effect on the feel of coating digital printed fabrics.Gao et al. (Gao D, Feng J, Ma J, et al. Synthesis of cationic binder through surfactant-free emulsion polymerization for textile pigment applications [J]. Progress in Organic Coatings, 2014, 77 (11): 1834-1840.) used the cationic monomer diallyldimethylammonium chloride and the hydrophobic monomers butyl acrylate, methyl methacrylate and hydroxyethyl acrylate to prepare a cationic P (DMDAAC-BA-MMA-HEA) copolymer emulsion through soap-free emulsion polymerization. The cotton fabric pre-treated with the emulsion had a dry and wet rubbing fastness of 3-4 and a soap washing fastness of 4.

[0004] However, since fabrics such as polyester are negatively charged, they can also form a strong affinity with the cationic polymers on the fabrics, especially as the molecular weight of the cationic polymers increases and the water solubility decreases, the affinity between the fabric and the polymers increases. During the use of printed fabrics, since the polymers in the pretreatment solution are difficult to be washed off during washing, these cationic polymers will absorb anionic substances such as dyes that fall off the fabric in the same bath through the electrostatic force between "anion-cation" ions, causing quality problems such as fabric staining during washing.

[0005] In view of the above situation, the present invention copolymerizes cationic monomers with water-soluble nonionic monomers, and at the same time, uses a chain transfer agent to reduce the molecular weight of the copolymer, thereby improving the washability of the cationic polymer and achieving balanced anti-seepage and anti-staining properties of the pretreatment agent based on the cationic polymer. Summary of the invention

[0006] In view of the problems in the prior art, the present invention provides a cationic coating digital inkjet printing pretreatment liquid and its preparation method and application, wherein a cationic monomer is copolymerized with a water-soluble nonionic monomer, and the electrostatic force between the cationic monomer and the surface of a negatively charged fabric such as polyester is used to regulate the deposition of dye particles on the fabric surface during inkjet printing, thereby avoiding penetration, reducing the amount of slurry used, and reducing the effect of the slurry on the fabric feel. During copolymerization, a chain transfer agent is also used to reduce the molecular weight of the copolymer, improve the washability of the cationic polymer, and achieve balanced anti-seepage and anti-staining properties of the pretreatment agent based on the cationic polymer.

[0007] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0008] A cationic coating digital inkjet printing pretreatment liquid is prepared by using the following components in percentage by weight based on 100% of the total weight:

[0009]

[0010]

[0011] In the cationic coating digital inkjet printing pretreatment liquid, the cationic monomer is one or two of dimethyldiallylammonium chloride and methacryloyloxyethyltrimethylammonium chloride.

[0012] In the cationic coating digital inkjet printing pretreatment liquid, the water-soluble nonionic monomer is one or both of acrylamide and hydroxyethyl acrylate.

[0013] In the cationic coating digital inkjet printing pretreatment liquid, the crosslinking monomer is N,N'-methylenebisacrylamide; the initiator is potassium persulfate; and the chain transfer agent is dodecanethiol.

[0014] The present invention copolymerizes cationic monomers with water-soluble nonionic monomers in the presence of a chain transfer agent to obtain a cationic paint printing pretreatment liquid; the pretreatment liquid is arranged on the fabric, and the treatment liquid forms an electrostatic attraction with negatively charged paint particles printed on the fabric through its own cationicity, so that the latter is deposited on the fabric surface, which not only avoids its infiltration, but also improves the apparent color gain of the fabric; at the same time, due to the high efficiency of electrostatic adsorption, the amount of slurry used in the pretreatment is reduced, the slurry has little effect on the feel of the fabric, and the feel of the fabric after printing is improved. In addition, thanks to the control of the chain transfer agent and the copolymerization of the hydrophilic monomer, the molecular weight of the resin in the pretreatment liquid is low, the water solubility is high, and it is easy to wash off, and the anti-staining performance of the paint printed fabric when worn and washed is also improved.

[0015] A method for preparing a cationic coating digital inkjet printing pretreatment liquid comprises the following steps:

[0016] Step 1: Add cationic monomer, crosslinking monomer and deionized water to the reactor in sequence, raise the temperature to 50-70°C under the protection of protective gas, add chain transfer agent and dissolve the initiator in the remaining amount of deionized water, inject the emulsion to initiate polymerization, and react at a constant temperature of 50-70°C for 0.5-1.5h;

[0017] Step 2: Raise the reaction temperature to 80-100°C, drip an aqueous solution of a water-soluble nonionic monomer, a chain transfer agent and an initiator into the reactor for 1-3 hours, and react at a constant temperature of 80-100°C for 2-6 hours to obtain the product.

[0018] Preferably, the reaction temperature is raised to 55-65°C for 1 hour, or the reaction temperature is raised to 85°C for 3-4 hours.

[0019] The application of the above-mentioned cationic paint digital inkjet printing pretreatment liquid in textile paint digital printing: adopting the padding process, and baking at 100-150°C for 80-100s, and then placing the pre-treated fabric flat on the paint digital inkjet printer for printing. After printing, use a pressing machine to dry the fabric at 140-180°C for 60-90s to complete printing.

[0020] Preferably, the baking temperature is 100-120° C., the baking time is 70-90 seconds, the pressing machine temperature is 150-170° C., and the pressing and drying fabric time is 70-80 seconds.

[0021] The present invention synthesizes a cationic polymer used as a pre-treatment agent for digital pigment printing, and its principles and advantages are as follows:

[0022] 1. Cationic pretreatment agents can weaken the electrostatic repulsion between anionic coating particles in ink, reduce water dispersion stability, promote rapid deposition from ink, and stably combine with cationic polymers by ionic bonds, fix on the fabric surface, prevent colored coating particles from penetrating the fabric, improve the pattern fineness, apparent color depth and brightness of coating digital printing, enhance the pattern layering and three-dimensional sense of processed fabrics, and give coating digital printing fabrics a higher fastness level and a new style;

[0023] 2. On the one hand, the hydrophilicity of the pre-treatment agent is enhanced by copolymerization with a non-ionic hydrophilic monomer; on the other hand, the molecular weight of the pre-treatment agent is reduced by a chain transfer agent; the combination of the two significantly improves the washability of the pre-treatment agent. The technology of the present invention is used to perform a pre-treatment of the fabric for digital printing of coatings. Since the pre-treatment agent is easy to wash off, the printed fabric not only has an improved feel, but also has a higher anti-staining performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a digital print of the cationic coating digital inkjet printing pretreatment solution prepared in Comparative Example 2 and Example 3;

[0025] Figure 2 This is a weft line print diagram of the cationic coating digital inkjet printing pretreatment solution prepared in Comparative Example 2 and Example 3;

[0026] Figure 3 The staining diagram of the cationic coating digital inkjet printing pretreatment liquid prepared in Comparative Example 3 and Example 3;

[0027] Figure 4 It is a wet and dry friction fastness diagram of the cationic coating digital inkjet printing pretreatment liquid prepared in Comparative Example 3 and Example 3. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

[0029] In a specific embodiment of the present invention, the preparation of the cationic coating digital inkjet printing pretreatment liquid specifically includes:

[0030] A mixture of methacryloyloxyethyltrimethylammonium chloride, hydroxyethyl methacrylate and water was added to the reactor and heated to 60°C with stirring. Dodecanethiol and potassium persulfate aqueous solution were added. After reacting for 0.5 h, the temperature was raised to 85°C. N,N'-methylenebisacrylamide, dodecanethiol and potassium persulfate aqueous solution were added dropwise to initiate polymerization. The reaction was continued at 85°C for 4 h, and then the reaction was stopped and the temperature was lowered to room temperature (25°C).

[0031] The process for digital printing of textile coatings specifically includes the following steps: using a padding process and baking at 120°C for 80 seconds, then placing the pre-treated fabric flat on a coating digital inkjet printer for printing, and after printing, using a pressing machine to dry the fabric at 160°C for 80 seconds to complete printing.

[0032] Examples 1 to 5 and Comparative Examples 1 to 3:

[0033] Table 1 Formulation (Kg)

[0034]

[0035] Note: The remaining substance is deionized water, with a total mass of 100 kg.

[0036] Table 2 Formulation (Kg)

[0037]

[0038] Note: The remaining substance is deionized water, with a total mass of 100 kg.

[0039] Table 3 Test results

[0040]

[0041] Description of the characterization methods involved in the embodiments and comparative examples:

[0042] The K / S value is obtained by measuring each fabric with a Datacolor spectrophotometer. The larger the K / S value, the darker the surface color of the sample, and the smaller the K / S value, the lighter the surface color of the sample.

[0043] The staining test is carried out according to GB / T 31127-2014 "Textiles - Tests for colour fastness - Color fastness of joints";

[0044] The line width in the warp and weft directions is measured by using a paint inkjet digital printing machine to print thin lines with a width of 0.2 mm along the warp and weft directions of the polyester-cotton fabric, and the actual width of the lines is measured using Image J software to evaluate the fineness of the printing. The smaller the actual width, the higher the fineness.

[0045] The rubbing fastness test is carried out in accordance with GB / T 3920-2008 "Textiles - Tests for colour fastness - Colour fastness to rubbing";

[0046] The fabric washing fastness test is carried out in accordance with GB / T 3921-2008 "Textiles - Tests for colour fastness - Colour fastness to washing with soap".

[0047] Figure 1 This is a digital print of the cationic coating digital inkjet printing pretreatment solution prepared in Comparative Example 2 and Example 3. Figure 1 It can be seen that compared with Comparative Example 2, after using the cationic printing pretreatment liquid of Example 3, the bleeding is small and the color of the printed fabric is darker, indicating that the apparent color yield is higher.

[0048] Figure 2 The following are the weft line prints of the cationic coating digital inkjet printing pretreatment liquid prepared in Comparative Example 2 and Example 3. As can be seen from the figure, the lines on the original polyester-cotton fabric are relatively wide, and the printing fineness is relatively poor. The comparative example 2 with the addition of anionic ions improves the fineness by about 22.8% compared with the original polyester-cotton fabric, and the example 3 with the addition of cationic monomers improves the fineness by about 34.3% compared with the original polyester-cotton fabric, indicating that the addition of cationic monomers is beneficial to inhibiting the wicking effect of the fiber and reducing the penetration of the ink.

[0049] Figure 3 The staining diagrams of the cationic coating digital inkjet printing pretreatment liquids prepared in Comparative Example 1, Comparative Example 3 and Example 3 are shown. As can be seen from the figure, compared with Comparative Example 1 and Comparative Example 3, the anti-staining level of Example 3 is significantly improved, reaching level 4, which indicates that the addition of the chain transfer agent can reduce the molecular weight of the copolymer and improve the washability of the cationic polymer.

[0050] Figure 4 The wet and dry friction fastness diagram of the cationic coating digital inkjet printing pretreatment liquid prepared in comparative example 3 and embodiment 3. It can be seen from the figure that the wet and dry friction fastness of the original polyester-cotton fabric after printing is relatively low, which are 4 and 2-3 respectively. The wet and dry friction fastness of comparative example 1 without adding crosslinking monomer is improved to a certain extent, but the improvement is small. The wet and dry friction fastness of embodiment 3 with adding crosslinking agent shows better wet and dry friction fastness, which are 4-5 and 3-4 respectively. It shows that the addition of crosslinking agent can effectively enhance the wet and dry friction fastness of coating digital inkjet printing fabric.

[0051] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A cationic coating digital inkjet printing pretreatment liquid, characterized in that: Based on 100% of the total mass, it is made of the following components in percentage by mass:

2. The cationic coating digital inkjet printing pretreatment liquid according to claim 1, characterized in that: The cationic monomer is one or both of dimethyldiallylammonium chloride and methacryloyloxyethyltrimethylammonium chloride.

3. The cationic coating digital inkjet printing pretreatment liquid according to claim 1, characterized in that: The water-soluble nonionic monomer is one or both of acrylamide and hydroxyethyl acrylate.

4. The cationic coating digital inkjet printing pretreatment liquid according to claim 1, characterized in that: The cross-linking monomer is N,N'-methylenebisacrylamide.

5. The cationic coating digital inkjet printing pretreatment liquid according to claim 1, characterized in that: The initiator is potassium persulfate.

6. The cationic coating digital inkjet printing pretreatment liquid according to claim 1, characterized in that: The chain transfer agent is dodecanethiol.

7. The method for preparing a cationic coating digital inkjet printing pretreatment liquid according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: add cationic monomer, crosslinking monomer and part of deionized water to the reactor in sequence, raise the temperature to 50-70°C under the protection of protective gas, add part of chain transfer agent, part of initiator and part of deionized water to initiate polymerization, and react at a constant temperature of 50-70°C for 0.5-1.5h; Step 2: Raise the reaction temperature to 80-100°C, drip water-soluble nonionic monomer, remaining chain transfer agent, remaining initiator and remaining deionized water into the reactor, the dripping time is 1-3h, and react at a constant temperature of 80-100°C for 2-6h to obtain a cationic coating digital inkjet printing pretreatment liquid.

8. Use of the cationic coating digital inkjet printing pretreatment liquid according to any one of claims 1 to 6 in textile coating digital printing.

9. The use according to claim 8, characterized in that: The digital printing of textile paint adopts the padding process and bakes at 100-150℃ for 80-100s. Then the pre-treated fabric is placed flat on the paint digital inkjet printer. The paint digital inkjet printer uses cationic paint digital inkjet printing pretreatment liquid for printing. After printing, use a pressing machine to dry the fabric at 140-180℃ for 60-90s to complete the printing.

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