Study on The Abrasive Dispersion of Dyes in Hot Sublimation Ink

Thermal sublimation dyes can be used in the preparation of thermal sublimation inkjet inks. Thermal sublimation inkjet inks usually disperse the thermal sublimation dyes in the water phase, and print exquisite images on specific transfer media by inkjet printers. The media are superplaced on the transferred body, and the dye is realized by heating sublimation transfer. As far as the printing effect is concerned, the color sublimation printer can meet the delicate and delicate skin texture needed for portrait printing, with gorgeous and rich colors, excellent performance such as water resistance, rub resistance and sun resistance, mild to the skin and friendly to the environment.

 

Thermal sublimation dye varieties for disperse dyes, disperse dye ink – jet.

 

Ink is a hot spot in the research of printing and dyeing and digital printing. In line with the requirements of ink-jet color matching disperse dye crystal structure is close, insoluble in water, when the thermal sublimation ink is stored for a long time or shut down storage in the ink cartridge, insoluble disperse dye particles will be deposited, resulting in a decrease in the color density of the printed image, shut down and then printed will appear serious color imbalance. In addition, the fineness and stability of the particle of the printer nozzle are very high, and the nozzle will be blocked seriously. Therefore, the key to solve the above problems is to make the thermal sublimation dye into a stable dispersion.

In this paper, Toynol abrasive dispersant, DS-172, DS-191, as the experimental object, red and blue two disperse dyes were processed, and their dispersion effect was compared with the effect of imported dispersant.

Ⅰ. Theory

1. Selection of Thermal Sublimation Ink Dye

The thermal sublimation ink disperses the thermal sublimation dye in the water phase. The ink is printed beautifully on the specific transfer medium by inkjet printer, and then the transfer medium is superimposed on the transferred body, and the dye is realized by heating sublimation transfer.

As a thermal sublimation dye, it needs to have the following characteristics:

(1) High sublimation, good storage stability at room temperature;
(2) Good heat resistance, in the printing nozzle heating environment, does not produce thermal decomposition;
(3) Good color reproduction after transfer;
(4) Good light resistance and chemical resistance;
(5) High particle dispersion.

From the chemical structure to determine suitable for use as thermal sublimation ink dye structure is as follows:

  • tricyanoethylene dyes;
  • dicyanoethylene dyes;
  • malononitrile dimer derivatives dyes;
  • azo dyes, etc.;

Dyes are divided into:

  • disperse dyes;
  • direct dyes;
  • acid dyes;
  • VAT dyes;
  • reactive dyes and so on.

The actual commercial thermal sublimation ink used disperse dyes, the reason is that disperse dyes with inkjet ink acceptable color light.

Blue ink selection: C.I. dispersion blue 14, C.I. dispersion blue 28, C.I. Dispersion blue 56, C.I. Dispersion blue 60, C.I. dispersion blue 72, C.I. Disperse blue 73, C.I. Disperse blue 77, one or more dyes.

Red ink selection :C.I. dispersion red 4, C.I. dispersion red 22, C.I. Dispersal red 55, C.I. Dispersal red 59, C.I. dispersal red 146, C.I. Disperse one or more dyes such as red 152.

Yellow ink selection :C.I. dispersed yellow 51, C.I. dispersed yellow 54, C.I. Disperse yellow 65, C.I. Disperse yellow 82, one or more dyes.

Limited to the requirements of the nozzle and inkjet process, the average particle size of the thermal sublimation dye in the ink is controlled within 60 ~ 200nm, and the maximum physical particle size of each component in the ink shall not exceed 1μm.

2. Dispersion Process of Dye Powder

In line with the requirements of ink-jet color matching disperse dyes are tightly crystal structure, insoluble in water dyes. Therefore, in the grinding process, it can be regarded as the grinding of insoluble powder.

(1) The Dispersion Morphology of Powder Changes

The powder is dispersed in the aqueous medium and always in the dynamic balance of dispersion (deflocculation)←→ flocculation, as shown in Figure 1 below. In order to obtain stable dispersion, intervention measures should be taken to promote the above dynamic equilibrium to move to the side of de-flocculation.

(2) Disperse Equipment

Before dispersing powder operation, it is necessary to have a certain understanding of dispersing equipment, grinding machine and grinding plate is necessary, grinding medium for zirconia beads (or glass beads), zirconia beads (or glass beads) size selection and filling amount is very important. Ink-jet ink in the solid particle size requirements are very strict, the size of the larger blockage nozzle. Zirconium beads with a diameter of less than 0.4mm are recommended, and the filling rate of zirconium beads should reach 50% or more of the grinding space.

(3) The Relationship Between Surface Tension and Deflocculation

In the dispersion (de-flocculation) process, solid particles are “cut” at high speed, creating new surfaces and increasing specific surface area of particles, resulting in a sharp increase in surface energy. In the dispersion process, there is also a reverse reaction in which small particles combine to counteract the sudden increase in surface energy.

The macroscopic manifestation of this reverse reaction is that the agglomeration of particles in the dispersion causes the dispersion to return to coarsening, increasing viscosity, delamination and so on.

In order to prevent the reverse reaction, measures to reduce the surface energy of the system must be found. Theory and practice show that reducing the surface tension of dispersed medium (water) can promote the wetting of medium to particle surface and reduce the surface energy. Surface tension is divided into static surface tension and dynamic surface tension. The “cutting” operation of dispersion (deflocculation) is a continuous motion process until grinding to the fineness required by commercial requirements, so reducing dynamic surface tension and improving dynamic wettability are essential to ensure grinding efficiency. The decrease of the dynamic surface tension will promote the rapid anchoring of the dispersant and dye, so it is necessary to choose the appropriate wetting agent during the dispersion process.

(4) The Stability Principle of Dispersant to Solid Particles

Figure 2 shows that the dispersant is quickly adsorbed on the surface of solid particles, forming a complex compact layer structure, changing the charge density of the original compact layer and increasing the attraction and repulsion force. Figure 3 shows the polymer barrier between dye particles, which is called steric hindrance ERs.

According to DLVO theory — potential energy curve, it can be seen that the influence of dispersant polymer material on the stability of dispersion. If ERs is negative, the flocculation will be accelerated, and the polymer added will become flocculant. If ERs is positive, it will be an effective dispersant and enhance the dispersion stability. See Figures 4 and 5.

3. Action principle of Toynol abrasive dispersant

Toynol’s abrasive dispersant products DS-191 and DS-197 are water-soluble polymers synthesized by CPT(controlled polymerization technology). It can quickly wet the powder, reduce the dynamic surface tension of the system and anchor the powder at many points. The dispersant polymer will quickly anchor and isolate the small particles at the newly broken place, change the charge density of the particle tight layer, and achieve dispersion stability, as shown in Figure 6. Tu yi le dispersant and particle surface after reaching adsorption equilibrium, forming new micelle, change the powder to the adsorption of electric double layer structure, especially the fixed layer structure and the change of the power, the adsorption of the tu yi le dispersant has higher overall energy barrier between micelle, can’t close to each other to prevent particles flocculation again, as shown in figure 7.

Ⅱ. The Experiment

1. The Experimental Equipment and Materials

The Experiment Equipment:

  • Ysdf-400w multifunctional dispersing machine (Shanghai Yuesheng Electronic Equipment Co., LTD.);
  • Tdl-5a table top Low-speed centrifuge (Jiangsu Jintan Baita Xinbao Instrument Factory);
  • Xsp-2ca biological microscope (Tianjin Shangguang Precision Optical Testing Instrument Sales Co., LTD.);
  • Rotational viscometer (BrookfieldDV-I Prime);
  • Electronic balance (Shanghai Yousheng Weighing Instrument Co., LTD.);
  • Zirconia beads (0.4 ~ 0.5mm)(Saint-Gobencish Pomgei (Handan) Co., LTD.)

The Experiment Materials:

  • Disperse red FB(C.I. Disperse red 60), C.I. disperse blue 72;
  • Toynol DS-191L dispersant (Tianjin Saifei Chemical);
  • Toynol DS-197 dispersant (Tianjin Saifei Chemical);
  • Toynol DF-220 defoaming agent (Tianjin Saifei Chemical);
  • Dispersant PCE (Clariant);
  • Dispersant 4560(BASF).

2. Experimental Operation

Add the measured deionized water and each grinding dispersant to the container, stir evenly at low speed and add thermal sublimation dry dye powder. After complete wetting, add grinding medium (zirconia beads), grind at 3000±50r/min speed for 4h, filter out the material.

Toynol DS-191L, DS-197, ClariantPCE and BSAF-4560 water-based abrasive dispersants were used to grind the same thermal sublimation dye under the same operating conditions. If foam spilled during the grinding process, Toynol DF-220 defoaming agent was added.

The grinding effect of various auxiliaries on thermal sublimation dyes was compared.

3. The List of Materials

(1) Dispersion Effect

Use plastic head dropper to take a drop of color slurry, drop in 20mL water, stir evenly, take a drop of water solution drops on the slide, pressure on the cover, microscope slide samples, placed in XSP-2CA biological microscope observation table, respectively in 640 χ, 1600 χ two multiple lenses, observe the particle size and agglomeration.

(2) Centrifugal Stability Evaluation

Take 20mL color paste into a centrifuge tube, centrifuge at 3000r/min for 10min, take out and observe the layer of color paste, pour out the liquid, calculate the amount and percentage of precipitate.

(3) Viscosity Evaluation

Put 80mL color paste into 100mL wide mouth flask and measure viscosity with rotary viscometer.

(4) Viscosity Stability

The paste was stored in a 100mL wide-mouth bottle, sealed at 40℃ for 24h, and the viscosity change was measured. The change of ±50% was considered qualified.

(5) Placement Stability

The paste was placed at room temperature at 25℃ for 15 days to observe the dispersion state (condensation, etc.) under the microscope.

Ⅲ. The Result and Discussion

1. Analysis of experimental results of dispersing red FB

Toynol DS-191L, ds-197, ClariantPCE and bsaf-4560 grinded dispersed red FB respectively, and the experimental results were shown in table 3.

The addition amount of Toynol DS-191L is 15% of the whole system, which can quickly moisten disperse dye dry powder. During the grinding process, the viscosity is small and the foam is low. The fineness is 500nm after grinding for 2h, and 200nm after grinding for 4h, which meets the fineness requirements. After 15 days of closed storage, there is no thickening and thickening.

The amount of toynol is a 15cent amount, which can be quickly wetted and dispersible dye dry powder, which is small in the grinding process, low in foam, and after the grinding of 2h, which is 500nmmm, and then the 3h is 200nm.which is the requirement of the finer degree. The color pulp is closed for 15 days without thickening, and the return of coarse phenomenon.

Clariantpce, which is 20 percent of the total, has a serious bubble and requires a partial addition of foaming agent to prevent foam overflow. After grinding 2h, the fine length is the same as the length of 1000nm. the length of the length of 4h is 500nm. the length of the time is 300nm. After 15 days of sealing, there is no obvious return to the coarse phenomenon, and the bottom of the container has a small amount of precipitation.

Basf-4560, which is 23 percent of the total, has a serious bubble, and it needs to be done in a batch of foaming agent to prevent the foam from overflow and the dispersion process is sticky. After grinding 2h, the fine degree is 1000nmm, and the length of the 4h is 800nm. the length is 500nm. The color of the color pulp is closed for 15 days and the viscosity increases, the return is clear, and the bottom of the container is precipitated.

2. Analysis of The Experimental Results of The Dispersion of Blue 72

C.I was treated with Toynol ds-191l, ds-197, ClariantPCE and bsaf-4560 respectively. Disperse blue 72 for grinding, and the experimental results are shown in Table 4.

When the addition amount of Toynol DS-191L is 15% of the whole system, it can quickly wet the disperse dye dry powder, and the viscosity is small and the foam is low in the grinding process. The fineness is 500nm after grinding for 2h, and 200nm after grinding for 4h, meeting the fineness requirements. There is no thickening and thickening after 15 days of closed storage.

When the addition amount of Toynol DS-197 is 15% of the whole system, the dry disperse dye powder can be quickly moistened, and the viscosity is small in the grinding process, the foam is low, and the fineness is 300nm after 2h grinding. The fineness is 200nm after grinding for 3h, which meets the fineness requirements. There is no thickening and thickening after 15 days of closed storage.

When ClariantPCE was added to 20% of the whole system, foaming was serious, and antifoaming agent needed to be added in batches to prevent foaming overflow. The slurry is thick and the fineness is > 1000nm after grinding for 2h. The fineness is 500nm after grinding for 4h, and 200nm after grinding for 6h. After 15 days of closed storage, there is no obvious coarse phenomenon, and a small amount of precipitation at the bottom of the container.

Basf-4560 blistered seriously when the additive amount was 23% of the whole system, so it was necessary to add defoaming agent in batches to prevent foam overflow and viscosity in the dispersion process. The fineness is > 1000nm after grinding for 2h. After grinding for 4h, the fineness was 800nm, and after prolonged to 6h, the fineness was 800nm, and no longer decreased. After 15 days of closed storage, the viscosity increased and the thickness returned obviously, and there was hard precipitation at the bottom of the container.

Disperse dye particles are very hard, grinding time to achieve 4h and above to achieve ink requirements. Thermal sublimation ink needs to be stored in the cartridge for a long time, if the particles of disperse dye paste appear coarse, resulting in deposition, serious will form nozzle blockage. As can be seen from FIG. 9 and 10, Toynol DS-191L, Toynol DS-197 and ClAR-Ian PCE particles do not aggregate or regrow during long-term storage.

Thermal sublimation inks are four-color inks, milled carbon black (mitsubishi MA100, Japan) using Toynol ds-191l and Toynol ds-197 and ClariantPCE using the method in this paper. The dispersing effect of yellow 82 was very good.

Ⅳ. Conclusion

1. By grinding C.I. disperse blue 72 and disperse red FB, Toynol ds-191l, Toynol ds-197 and ClariantPCE can achieve dispersion and stability.

2. Toynol DS-191L and Toynol DS-197 have low foaming in the process of grinding disperse dyes, and dF-220 defoaming agent can control foam sustainably.

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