Application of IPN Surface Modification in Inkjet Printing

Because of its small particle size, surface-modified IPN pigment particles are characterized by high color strength and good stability. Using this pigment for paint printing can greatly reduce the amount of pigment in the color paste, and at the same time, the particles have small rubbing fastness. Well, no dispersant can reduce the factors that affect the color fastness due to dispersants, and because the amount of pigment can be reduced while the amount of adhesive can be used to solve the problem of hand feeling, it is worth to promote it to paint printing for research.

Inkjet printing technology has been used in many applications. If the speed is improved, it will gradually replace the printed version. At present, the price of ink for ink jet printing is relatively expensive, and it also restricts its promotion in textile printing. In addition to the fact that the price is expensive, in addition to the factors that require new technologies to obtain high profits, there are also high objective requirements, resulting in high manufacturing costs. Inside. Inkjet printing is far less than the printed version, and in the case of a small amount of printing ink, high-purity pigments must be used for deep dark colors, and the concentration of colorants in the ink is also quite high. This requires that the pigments or dyes have a very good dispersibility or solubility, which are very harsh conditions and accordingly increase the cost.

Inkjet printing inks consist of several major components: first, colored substances that meet the requirements for color fastness; second, solvents or dispersants; third, thickeners that increase viscosity; and fourth, adhesives that improve fixation and staining. The fifth is to prevent cognac moisture absorption.

Colored substances are commonly used as color pigments (inorganic and organic pigments) and dyes. Inorganic pigments are mainly carbon black, and there are many organic pigments. Pigments used in ink-jet printing ink must meet the following requirements: particle size size of 10 to 300 nm: In the particle size of not more than 0.5 microns, solid concentration of 15%, particles per milliliter to reach the 10th power; On 3 micron nylon filter paper, 100 ml of ink must have 10% of solid pigment to be filtered; the purity of the pigment should be greater than 800% (referring to the extractables); at 25°C for one week, the above performance change cannot be achieved. Greater than 50%, its stability is better; can withstand high shear stress.

In order to achieve stable dispersion of fine particles, dispersing agents have been used in the past for dispersion, but when the dispersing agent is removed, the pigment particles immediately aggregate into large particles. However, it is not allowed to have a large amount of dispersant in the ink, otherwise the pigment concentration requirement cannot be achieved, and the dispersant will also reduce the color strength, stretchability and elasticity of the pigment. Therefore, dispersant dispersion methods are generally not used in printing inks. It has been studied that the surface of the pigment particles is modified to become pigment particles that can be dispersed and have a large electrokinetic layer potential on their surfaces so that they will not aggregate in the liquid and maintain a stable dispersion. Therefore, Recently, the study of denaturation of pigment particles has attracted everyone's interest. At present, there are roughly two methods for surface modification of pigment particles: First, surface modification is performed with a diazo agent, and the diazo agent is a nitrogen-containing compound having an aromatic group, and a carboxylic acid and sulfonic acid group having an ionizable group such as an anion. Or cationic quaternary ammonium group. Second, using the IPN method, the polymers that participate in the interpenetrating network include polyethylene, polyvinyl chloride, polystyrene, polyimide waist, and polythene. The method of surface modification with IPN works well. In addition to the interpenetrating network polymer IPN and the semi-interpenetrating network polymer s-IPN method, recent patents have reported the development of simultaneous interpenetrating network polymers (SIN for short) or interpenetrating elastomeric polymers (referred to as IEN). , Preparation of chemically bonded polymers, the effect is more obvious.

Interpenetrating Polymers (IPN)

The interpenetrating network polymer is currently divided into two types of full-interpenetrating polymer networks (IPNs) and semi-imerpenetrating polymer networks (s-IPNs or semi-IPNs). The so-called IPN originally referred to two or more unreacted polymers in the middle of the process of preparing the first polymer or adding the polymer or monomers of the second polymer to react . The latter penetrates between the first high polymer molecular chains. After the completion of the reaction, the polymer molecules interpenetrate to form a network system. The interpenetrating polymers do not undergo a chemical reaction but cross-penetrate each other. Mechanical entanglements play "forced miscibility" and "synergy." This tangling between the networks significantly improves the dispersion of the system and the hydrophilicity of the interface, thereby increasing the relative stability, realizing complementary properties of the polymer and achieving the purpose of modification. Therefore, IPN is an effective method to improve the properties of polymer materials.

The polymers that participate in the interpenetrating network may be linear polymers, linear ones, cross-linked polymers, or cross-linked polymers. Although the two high polymer molecules do not covalently bond, the second polymer permeates into the first high polymer molecular chain randomly and is networked, changing the phase properties of the high polymer to make the high polymer modified.

The main factors affecting IPN performance are: the degree of network interpenetration, the ratio of components participating in the interpenetrating network polymer, the degree of cross-linking, and the method of preparation.

The choice of IPNs is the primary task for the development of IPN products. Not all polymers can form IPNs, depending on their compatibility. Incompatible polymers do not have the ability to produce 1PN polymers. To adapt to the preparation of IPN, generally meet three conditions: two polymers can be synthesized or crosslinked in the presence of another polymer; two polymers have similar dynamic properties; two polymers No significant phase separation occurs.

These conditions are now also some breakthroughs, such as the large difference in dynamic performance, and now also made IPN, mainly synthetic technology is improving. When two cross-linked polymers are used to make IPN, they are separately synthesized and then networked to make IPN.

The difference between IPN and polymer complexes, block copolymers, and graft copolymers is that IPN is insoluble in solvents and can only swell, whereas the latter can be dissolved, and the IPN's peristaltic and flow are suppressed.

Semi-IPN

The semi-interpenetrating network polymer and the fully interpenetrating network polymer are basically the same, the main difference is that the configuration is different. From the configuration point of view, s-IPN can be divided into non-covalent and covalent ( There are two types of cova-lents. For non-covalent IPNs, all-IPNs are their own cross-links of the two polymers and exist in the network. The s-IPN is a network of crosslinked polymers and a non-crosslinked polymer. In the covalent s-IPN, the two cross-linked polymers are then cross-linked and networked to form a single network polymer. The difference between it and the non-covalent all-IPN is that the latter does not cross-link. Cross-linking between polymers. Therefore, it is simply considered that s-IPN is a cross-linked interpenetrating network polymer in which cross-linking reaction occurs between two polymers. Because s-IPN polymers crosslink with each other, increasing the cross-linking points between the polymers, the extension performance of s-IPN is not as good as that of all IPNs. However, other performance does not necessarily mean that s-IPN is worse than IPN.
Author: Huang Maofu Source: China Textile News