CN110591537B

CN110591537B - Coating agent and preparation method and application thereof

Info

Publication number: CN110591537B
Application number: CN201911061831.9A
Authority: CN
Inventors: 陈镜宏; 林侨阳
Original assignee: Dongguan Huayin Information Technology Co ltd
Current assignee: Dongguan Huayin Information Technology Co ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2021-08-10
Anticipated expiration: 2039-11-01
Also published as: CN110591537A

Abstract

The invention provides a coating agent and a preparation method and application thereof, wherein the coating agent comprises the following components in percentage by mass based on 100% of the total mass of the coating agent: 45-70% of modified polyurethane; 6-12% of ink absorbing powder; 0.1 to 0.5 percent of defoaming agent; 0.2 to 2.0 percent of dispersant; the balance of deionized water. The coating agent provided by the invention can solve the problems of bleeding, ink piling, shrinkage and the like of the water-based paint ink-jet ink on the surface of leather; and after the water-based paint ink is cured, the adhesive force with the ink can be improved.

Description

Coating agent and preparation method and application thereof

Technical Field

The invention belongs to the technical field of leather surface treatment liquid, and relates to a coating agent, and a preparation method and application thereof.

Background

The leather industry covers the main industries of leather making, shoes making, fur clothing, leather pieces, fur and products thereof, and is closely related to the daily life of residents. The printing market potential of leather and products thereof is very large, and the printing modes of the leather and the products thereof comprise dye printing, pigment printing, ink-jet printing and transfer printing.

The dye printing has the greatest advantage that the hand feeling is not affected, but leather cannot resist high-temperature steaming, so that the textile cannot be carried by the process; the steaming-free dye is mainly a 1:2 type metal complex dye, and the leather is printed by using the steaming-free dye without steaming and drying, but the dye is high in price, the strength of the dye is only 30 to 50 percent of that of the common dye, and deep and thick color printing is difficult to perform. The digital printing realizes that the data of the computer is output to the leather printing machine-the printing is directly sprayed on the object, the ink-jet printing precision is high and close to the photo, the plate making is not needed, the printing is quick and the cost is low, the special color management software is matched, the color can be changed at any time and any place, the ink-jet printing is the most practical printing mode on the leather at present, the fineness of the pattern and the visual effect are comparable with those of other modes; however, the conventional UV ink has a problem of poor weather resistance; weak solvent inks have been used in a decreasing number of applications due to their strong odor. The water-based pigment printing is the printing with the largest amount in leather printing, because the pigment printing can express the golden and silver colors, and is matched with special processes such as flocking, foaming and the like, the product is more diversified, and the characteristics of noble and gorgeous leather can be expressed to the maximum extent. The transfer printing is divided into a dry method and a wet method; the dry transfer is mainly to make ink with hot melt adhesive, print on release paper or bopp mould, transfer on the leather under the hot-pressing condition again; wet transfer, spraying a special solution on the leather; and then the dye on the transfer paper is dissolved and dissolved by hot pressing, and then the dye is fixed on the leather.

The water-based paint direct-injection printing is used as a new process for printing leather. The method has the process characteristics of rapidness, high efficiency, no need of plate making, environmental protection and the like, and has the pattern effects of high precision, rich colors and the like. Theoretically, the coating ink is suitable for various fabrics, including leather and products thereof; however, because the surface compactness of the leather fabric is good, especially for materials such as artificial leather, the coating ink is difficult to wet and spread on the surface, and the phenomena of shrinkage, ink piling, adhesion reduction and the like can occur.

The leather coating ink-jet printing process comprises four important steps of leather pretreatment, ink-jet printing, baking and color fixing and after-finishing. The leather pretreatment is used as an important link in the paint ink-jet printing process, the used treatment liquid has important influence on the quality of ink-jet printing, and the performance needs to have the characteristics of bright color, clear ink-jet, excellent fastness and the like.

CN105442384A discloses a novel digital inkjet non-woven base paper, the coating raw material is composed of the following components by mass: 20-18 parts of water, 35-28 parts of calcium carbonate, 3-5 parts of superfine silicon dioxide, 32-22 parts of porcelain clay, 2-0.8 part of flatting agent, 1.5-0.5 part of activating agent and 30-35 parts of emulsion agent, the smoothness is higher, but the main components of the printing coating are filling powder and water-soluble adhesive, the coating has poor water resistance and can only be applied to paper-based materials. CN102501673A discloses a preparation method of a nano composite ink absorbing material for printing, which utilizes nano titanium dioxide, nano silicon dioxide and graphene powder as adsorbing materials, and matches with a proper coupling agent and a proper adhesive to improve the water resistance of a printing coating; however, the inorganic powder in the coating still affects the adhesion fastness.

In the inkjet printing technology, the pretreatment of leather is very important, and is related to the comprehensive properties of leather, such as weather resistance, etc., and the pretreatment process of leather has a great influence on the subsequent spreading of ink and the fastness of an ink layer, so that a new coating agent needs to be developed to meet the requirements of the inkjet printing process of leather coating.

Disclosure of Invention

The invention aims to provide a coating agent, a preparation method and application thereof, and the coating agent provided by the invention can solve the problems of bleeding, ink piling, shrinkage and the like of water-based paint ink-jet ink on the surface of leather; and after the water-based paint ink is cured, the adhesive force with the ink can be improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a coating agent, which comprises the following components in percentage by mass based on 100% of the total mass of the coating agent:

the coating agent provided by the invention comprises ink absorption powder, and the ink absorption powder can be uniformly dispersed in the modified polyurethane in the actual coating process to form a micro-phase separated sea-island structure, so that the structure is favorable for the subsequent wetting and spreading of the water-based coating ink-jet ink, and the shrinkage phenomenon of the water-based coating ink-jet ink on the surface of leather is further solved.

In the present invention, the modified polyurethane is 45 to 70%, for example, 46%, 48%, 50%, 52%, 55%, 57%, 60%, 62%, 65%, 68%, etc.

In the present invention, the ink-absorbing powder is 6 to 12%, for example, 7%, 8%, 9%, 10%, 11%, etc.

In the present invention, the defoaming agent is 0.1 to 0.5%, for example, 0.2%, 0.3%, 0.4%, etc.

In the present invention, the dispersant is 0.2 to 2.0%, for example, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, etc.

In the invention, the ink absorbing powder is polyacrylate solid powder.

Preferably, the polyacrylate solid powder is core-shell polyacrylate.

Preferably, the polyacrylate solid powder has a minimum film forming temperature of 70-90 ℃, such as 75 ℃, 80 ℃, 85 ℃ and the like.

The lowest film-forming temperature of the polyacrylate solid powder selected by the invention is 70-90 ℃, and for a leather coating ink-jet printing process, the pretreatment drying temperature of leather is generally below 60 ℃, so that the solid powder is not melted during coating treatment and can still keep the solid form, namely the polyacrylate solid powder and the modified polyurethane can form a sea-island structure, and further the wetting and spreading of subsequent ink are ensured; after the subsequent ink is subjected to color fixation at the temperature of more than 100 ℃, the polyacrylate solid powder can be melted to form a film, so that the bonding force between the coating agent layer and the ink layer can be further improved.

If the minimum film-forming temperature of the polyacrylate is too low, the polyacrylate is melted to form a film in the drying process of the coating agent, so that the ink cannot be wetted and spread; if the minimum film-forming temperature of the polyacrylate is too high, the polyacrylate cannot be melted into a film in the ink curing process, and the adhesion between the post-coating agent layer and the ink layer cannot be ensured.

Preferably, the polyacrylate solid powder has a particle size of 1 μm or less, for example 0.8 μm, 0.5 μm, 0.3 μm, 0.1 μm, 0.08 μm, 0.05 μm, 0.01 μm and the like.

When the particle size of the polyacrylate solid powder is less than 1 mu m, the polyacrylate solid powder and the modified polyurethane can form a micro-phase-separation type high polymer alloy, and the adhesion fastness of the coating agent before ink-jet printing can be improved through alloying, so that the phenomenon of coating agent coating falling or scratching is avoided.

In the invention, the modified polyurethane is selected from any one of or a combination of at least two of silicone modified polyurethane dispersion, acrylate modified polyurethane dispersion or epoxy resin modified polyurethane dispersion.

Preferably, the solids content of the modified polyurethane is 35 to 50 wt.%, such as 38 wt.%, 40 wt.%, 42 wt.%, 45 wt.%, 48 wt.%, and the like.

In the invention, the addition amount of the ink-absorbing powder is 40-60 wt% of the solid content of the modified polyurethane, such as 42 wt%, 45 wt%, 47 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt% and the like.

If the content of the ink absorption powder is too low, the distribution of the micro-phase separated sea-island structure is insufficient, and the ink wetting effect is reduced in the ink jet process; if the content of the ink absorption powder is too high, the adhesion fastness of the coating agent layer before ink-jet printing is affected, and the phenomenon of falling or scratching is easy to occur.

Preferably, the defoamer is selected from silicone based defoamers.

Preferably, the dispersant is a polymer block dispersant.

Preferably, the finish also includes a thickener.

Preferably, the thickener is present in an amount of 0 to 3.5% by mass, for example 0.5%, 1%, 1.5%, 2%, 2.5%, 3, etc., based on 100% by mass of the total coating agent.

Preferably, the thickener is selected from associative polyurethane thickeners, selected from Coapur 830W, ACRYSOL RM-8W, and the like.

The defoamer, dispersant and thickener described in this invention are all conventional choices in the art.

Preferably, the viscosity of the coating agent is 200-3000cP, such as 300cP, 500cP, 1000cP, 1500cP, 2000cP, 2500cP, and the like.

If the viscosity of the coating agent is too low, sizing operation is not facilitated; if the viscosity of the finish is too high, the leveling speed of the finish is slow, which is not favorable for forming a smooth coating.

In a second aspect, the present invention provides a method for preparing a finishing agent according to the first aspect, the method comprising the steps of:

(1) mixing and grinding deionized water, a defoaming agent, a dispersing agent and ink absorption powder, and then filtering by using a 1-micron filtering membrane to obtain a filtrate;

(2) and mixing the filtrate with modified polyurethane to obtain the coating agent.

If the modified polyurethane, the ink absorption powder, the defoaming agent, the dispersing agent and the deionized water are mixed by adopting a one-pot method, the ink absorption powder (polyacrylate powder) is difficult to disperse uniformly, the dispersing efficiency is low, and the overall viscosity is low.

The invention controls the grain diameter of the ink absorption powder in the coating agent to be below 1 mu m by adopting grinding and filtering methods.

Preferably, the preparation method further comprises the step of adjusting the viscosity of the coating agent to be 200-3000cP, such as 300cP, 500cP, 1000cP, 1500cP, 2000cP, 2500cP and the like, by using a thickening agent after mixing with the modified polyurethane.

Preferably, the milling is carried out until the ink-receptive powder has a particle size of 1 μm or less, such as 0.8 μm, 0.5 μm, 0.3 μm, 0.1 μm, 0.08 μm, 0.05 μm, 0.01 μm, etc.

In a third aspect, the present invention provides the use of a finish according to the first aspect in the pretreatment of leather.

Preferably, the pretreatment temperature is 30-70 deg.C, such as 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, etc.

Drying is needed after the leather pretreatment, and the general drying temperature is low-temperature drying, namely the temperature is lower than 60 ℃; the leather needs ink-jet printing, baking and color fixing after being pretreated, and the baking temperature is generally above 100 ℃ and generally 100-120 ℃.

Compared with the prior art, the invention has the following beneficial effects:

(1) the coating agent provided by the invention comprises ink absorption powder, and the ink absorption powder can be uniformly dispersed in the modified polyurethane in the actual coating process to form a micro-phase separated sea-island structure, so that the structure is favorable for the subsequent wetting and spreading of the water-based coating ink-jet ink, and the shrinkage phenomenon of the water-based coating ink-jet ink on the surface of leather is further solved;

(2) the lowest film forming temperature of the polyacrylate solid powder selected by the invention is 70-90 ℃, and the polyacrylate solid powder can be melted to form a film after fixation at more than 100 ℃ in the subsequent processes of ink-jet printing, baking and coloring in the leather paint ink-jet printing process, so that the binding power of a finishing agent layer and an ink layer can be further improved;

(3) the polyacrylate solid powder with the particle size of less than 1 mu m is selected, so that the compatibility with the modified polyurethane is favorably improved, the adhesion fastness of the coating can be improved after the coating agent is dried, and the whitening phenomenon does not occur at the bending and folding positions;

(4) the finishing agent provided by the invention can solve the problem of shrinkage of the water-based paint ink-jet ink on the surface of leather; after the water-based paint ink is cured, the adhesive force between the water-based paint ink and the ink can be improved; wherein the adhesion fastness is below 2, the dry rubbing fastness is above 4, the wet rubbing fastness is above grade 3, and the adhesion fastness after curing is increased.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The following examples and comparative examples relate to materials and brand information as shown in table 1:

TABLE 1

It should be noted that the toner is not completely dried and has a water content of about 2%, and therefore, when it is actually added for use, the toner is calculated based on the water content of 2% of the toner.

Examples 1 to 5

The coating was prepared according to the components shown in table 2, as follows:

(1) in a stirring device, uniformly stirring water, a defoaming agent and a dispersing agent, and then uniformly mixing the mixture with ink absorption powder;

(2) grinding with a sand mill (containing 0.5mm zirconium beads) at 3000r/min, filtering the dispersion with 1 μm glass fiber membrane, collecting the filtrate, and grinding to obtain polyacrylate with particle diameter shown in Table 2;

(3) mixing the filtrate with the modified polyurethane, and adding a thickening agent to adjust the viscosity to obtain the coating agent, wherein the viscosity is shown in table 2.

TABLE 2

Comparative examples 1 to 7

A coating agent was prepared by using the components shown in tables 2 and 3, and coating agents were prepared by the preparation methods provided in examples 1 to 3.

Comparative example 8

The difference from example 1 is that, unlike the preparation method, the grinding step is omitted, and the preparation method is as follows:

(2) mixing with modified polyurethane, and adding a thickening agent to adjust the viscosity to obtain the finishing agent.

Comparative example 9

The difference from example 1 is that, unlike the preparation method, the preparation method is as follows:

and (3) uniformly mixing water, a defoaming agent, a dispersing agent, modified polyurethane and ink absorbing powder in a stirring device, and adding a thickening agent to adjust the viscosity to obtain the coating agent.

TABLE 3

Performance testing

The finishes provided in examples 1-3 and comparative examples 1-9 were tested for performance by the following methods:

(1) adhesion fastness test of finishes

Selecting a 0.25 micron wire rod to be arranged on the surface of the hard leather, scraping a layer of uniform coating agent, baking for 5 minutes at 65 ℃, and carrying out adhesion fastness test on the pretreated leather, wherein the specific test method refers to ISO2409-2007 test of colored paint and varnish-grid drawing test;

(2) ink jet Effect test

Spray printing the untreated leather and the leather treated with the coating agent (0.25 μm wire rod on the leather surface, scraping a layer of uniform coating agent, baking at 65 ℃ for 5 minutes) by using P series water-based pigment textile printing ink produced by DuPont company, and observing whether the straight line edge is flat or not by using a 50-time magnifier, wherein:

a level: bright color, uniform ink drop and clear edge;

b stage: bright color, uniform ink drop, clear edge and little shrinkage;

c level: light color, slight accumulation of ink drops and jaggy;

d stage: very light color, ink droplet pile-up;

(3) color fastness test

According to the method described in the national standard GB/T3920-.

The test results are shown in table 4:

TABLE 4

As can be seen from the examples and performance tests, the water-based coating ink prints on the coating, has good wetting and spreading and good pattern printing effect because of the sea-island structure with separated micro-phases formed by the polyacrylate ink-absorbing powder. In addition, after high-temperature curing, the ink absorbing powder and the modified polyurethane form a compact coating, so that the adhesion and the dry-wet rubbing fastness are also good, wherein the adhesion fastness is below 2, the dry rubbing fastness is above 4, the wet rubbing fastness is above grade 3, and the adhesion fastness after curing is slightly increased.

As can be seen from the comparison of example 1 with comparative examples 1 to 2, when the lowest film-forming temperature of the polyacrylate solid powder is selected in the range of 70 to 90 ℃, the wet spreadability and the adhesion fastness after curing are more excellent. As can be seen from the comparison between example 1 and comparative example 3, and between example 3 and comparative example 4, too little or too much polyacrylate ink-absorbing powder brings about some disadvantages, and too little amount causes the ink to be difficult to wet the surface of the leather to be spread, and the ink layer forms some piles and craters. As can be seen from the comparison between the example 2 and the comparative example 5, after the coating agent is formed into a film, part of the powder is exposed on the surface of the coating, the porous structure of the powder can absorb ink drops and prevent the ink drops from diffusing, but the color can be lightened, and after the coating agent is cured at a high temperature in a later period, the gas-phase silica is taken as an incompatible component, so that the performances of the coating agent, such as the color fastness to rubbing, the adhesion force fastness and the like, can be reduced; meanwhile, the thickening effect of the fumed silica is very obvious, the viscosity of the prepared finishing agent is high, and the leveling property is poor during construction. As can be seen from example 1 and comparative example 6, when the ink absorbing powder is added to the coating agent of the present invention, spreading of subsequent ink is facilitated and color fastness of the ink at a later stage is increased. As can be seen from the comparison between example 2 and comparative example 7, when no thickener is added in the invention, the viscosity of the coating agent is too low, and the phenomenon of hole shrinkage occurs occasionally in construction; as is clear from comparison of example 1 with comparative examples 8 to 9, the advantageous effects of the present invention can be obtained only by selecting the production method of the present invention.

The applicant states that the coating agent, the preparation method and the application thereof are illustrated by the above examples, but the invention is not limited to the above detailed method, i.e. the invention is not meant to be dependent on the above detailed method. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. The coating agent is characterized by comprising the following components in percentage by mass based on 100% of the total mass of the coating agent:

the ink absorbing powder is polyacrylate solid powder;

the lowest film forming temperature of the polyacrylate solid powder is 70-90 ℃;

the particle size of the polyacrylate solid powder is less than or equal to 1 mu m.

2. The coating agent according to claim 1, wherein said modified polyurethane is selected from any one of silicone modified polyurethane dispersion, acrylate modified polyurethane dispersion, or epoxy resin modified polyurethane dispersion, or a combination of at least two thereof.

3. The coating agent according to claim 1, wherein the modified polyurethane has a solid content of 35 to 50 wt%.

4. The finishing agent of claim 1, wherein the ink-absorbing powder is added in an amount of 40 to 60 wt% based on the solid content of the modified polyurethane.

5. The coating agent according to claim 1, wherein said defoaming agent is selected from silicone defoaming agents.

6. The coating agent according to claim 1, wherein said dispersant is a polymer block dispersant.

7. The finish of claim 1, further comprising a thickener.

8. The coating agent according to claim 7, wherein the thickener is contained in an amount of 0.1 to 3.5% by mass based on 100% by mass of the total coating agent.

9. The finish of claim 7, wherein said thickener is selected from the group consisting of associative polyurethane thickeners.

10. The coating agent of claim 1, wherein said coating agent has a viscosity of 200-3000 cP.

11. Process for the preparation of a finish according to any one of claims 1 to 10, characterized in that it comprises the following steps:

12. The method as claimed in claim 11, wherein the method further comprises mixing the modified polyurethane with a thickener to adjust the viscosity of the coating agent to 200-3000 cP.

13. Use of a finish according to any of claims 1 to 10 in the pretreatment of leather.

14. Use according to claim 13, wherein the pre-treatment temperature is 30-70 ℃.