Solvent-impregnated resins

When NGu was used asone of the components of consumable cartridges, it was recrystallized from a satd aqueous soln into the pores of Kraft fiber prior to resin impregnation. When dicyanamidazide was employed, it was added as a component of the impregnating resin-solvent(Ref 23,pp I1I-V, 23, 25 27)... 

An interesting property of resins impregnated with oximes or oxines is that the selectivity of, for example, copper over iron(III), approaches that of a pure solvent-extraction process only when an inert solvent is present in the pores of the resin.396 Thus, in a /S-hydroxyoxime SIR, the selectivity for copper over iron(III) improved by a factor of 20 when the solvent perchloroethylene was introduced into the SIR, and by a factor of 700 in a similar resin impregnated with 8-hydroxy-quinoline.396 This is believed to be due to kinetic and thermodynamic restrictions in the extraction of iron(III), but not of copper, at an aqueous—organic boundary.396 397... 

No significant volumetric change was observed on oak samples after dehydration. On the other hand, deteriorated beech samples showed a mean volumetric shrinkage of 3% in both solvents. Acetone-impregnated samples were immersed for 2 weeks in Norsodyne and Ludopal resins diluted by 15% acetone in each first bath. The solutions were then changed three times by pure resins at 2-week intervals, totaling an impregnation time of 8 weeks for this final phase. 

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

Extraction with solvent impregnated resins. A. Warshawsky, Ion Exch. Solvent Extr., 1981, 8, 229-310(102). 

Phenolic resin is the most common resin because it is highly sticky with a hard carbon structure and low cost [9,12,13]. The paper is then put inside an oven at around 150-175°C in order to cure the resin and to remove the solvent [9,12]. The amount of phenolic resin that is impregnated also depends on the desired final characferisfics of fhe CFP. For example, high concenfra-fions of fhe phenolic resin reduce fhe fhickness of the paper, but the surface resisfivify decreases significanfly [13]. 

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