Thermosensitive layer

The thermosensitive recording paper itself is white like a plain sheet of paper. With the application of heat by means of a thermal pen or thermal head, the color-forming components in the thermosensitive layer are brought into reactive contact in the area delineated by the heat pattern... 

In addition to leuco dye and coreactant, many additives such as sensitizer, stabilizer, filler, lubricant, antipressure agent, etc. are used in the thermosensitive layer. 

Metallic soaps such as zinc stearate or calcium stearate are used as lubricant, which reduces the friction coefficient of the surface of the thermosensitive layer resulting in smooth running on recording machines. 

The smoothness of the surface of the thermosensitive layer has considerable influence on image intensity and image reproducibility. This is achieved by calendering of high line pressure. So, paraffin waxes are used as antipressure agent in order to prevent undesirable coloring on calendering. 

Oohashi, H. Kunita, K. Method for colored image formation using discoloring material in photosensitive-thermosensitive layer on lithographic printing plate precursors. Eur. Pat. Appl. EP 1602480,2005 Chem. Abstr. 2005,144,43249. 

More recently, researchers in Poland (Sibinski et al., 2010) have tried to transfer the manufacturing techniques directly onto fibres by successive coating. Polyvinylidene fluoride monofilaments were used as core sensors. A thermosensitive layer, composed of multiwalled carbon nanotubes within a polymethylmethacrylate matrix was added around the monofilament and was encapsulated by a silicon layer, leaving accessible only the contact points at each extremity. 

Preliminary testing demonstrates that the temperature sensor yarn was functional but only within a very short window, 30—45°C, and with large variation of the temperature coefficient of resistance. Optimizations of the thermosensitive layer as well as of the technique of encapsulation were recommended for further work. 

Substrate fibre Thermosensitive layer (a) Encapsulation coating ... 

For specialty papers, the coat layer can have functional properties. Examples are the thermosensitive layer of thermal papers or the capsule-containing coat layer of... 

Among the many kinds of the surface modification process, the fluid bed processes can most easily produce multilayered particle structure with each layer being monolithic, random multiphase structure, ordered multiphase structure, and so on (Fig. 5). The combination of the different components and layers can produce almost infinite types of functional particles. As an example, designs and preparations of several thermosensitive controlled-release particles will be described below. 

First, a high temperature may not be suitable (thermosensitive fine molecules, low volatibility,. ..). The second reason is that a liquid layer may be desired, to control the reaction path way, for instance by inhibiting or promoting secondary reactions in the liquid phase. From amongst the considerable number of cases, here are some examples of intentional addition of L component ... 

The admlceUar polymerization concept was also applied to the synthesis of thermosensitive magnetic latex particles based on V-isopropylacrylamide (NIPAM). In this case, however, the polymerization could be better defined as seeded precipitation polymerization owing to the water solubility of this monomer. Kondo et al. [116] were among the first to synthesize PNIPAM particles using Fe304 nanoparticles covered with two layers of OA and SDBS. V,V -Methylene bisacrylamide... 

Thermosensitive telefax paper contains a base paper and a thermosensitive colour-forming layer. Kanerva et al. (1992) reported occupational allergic contact dermatitis caused by colophony in telefax paper. Hand dermatitis that improved on job leave and during vacations and that relapsed on return to work was traced to colophony in telefax paper containing 1% colophony. Patch testing with this fax paper gave only partial reactivity (Kanerva et al. 1992). 

To this end, the machine building and textile industries have together developed what is known as the Caliweb process in which a warp-knitted spacer nonwoven Multiknit is used instead of the layer of foam. The nonwoven is clearly three-dimensional and is available from 3 mm to 8 mm thick. Fibres are mainly orientated in the third dimension and are integrated into both the meshed surfaces of the nonwoven (Fig. 3.3). Above this, their position is fixed by means of thermosensitive bonding fibres. This structure is as good as the foam which has been replaced. Composite formation between the decorative material and the nonwoven... 

A separate group of smart pol5miers is represented by particulate systems. Liposomes that reversibly precipitate on salt addition and removal were prepared from a synthetic phospholipid that had a diacetylene moiety in the hydrophobic chain and an amino group in the hydrophilic head of the phospholipid, followed by polymerization of diacetylene bonds (35). Latices composed of thermosensitive polymers or a layer of thermosensitive polymer at the surface represent another example of insoluble but reversibly suspended particulate systems that respond to increasing/decreasing temperature (31). 

The application of thermosensitive microbiological materials in product recirculation may influence a risk of thermal inactivation if part of the substance being dried stays too long in the heating zone during recirculation. In the case of spraying the material onto the bed of inert material, its particles are covered with a thin layer of wet material. With... 

Binder resins for coatings Epoxy crosslinker for photographic subbing layers Epoxy hardener for dry transfer colorations of metallic surfaces Thermosensitive copying paper resins... 

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