Water testing repellency

Water-repeUent fabrics resist wetting or repel waterborne stains they pass AATCC Test Method 22 (Spray Test). 

Although chemicals are now used extensively in the control of rice pests, the demand for chemicals in this field is expected to be much greater in the future. Many chemicals now available have not been tested in countries where severe losses occur. In the developmental field, more satisfactory herbicides are needed for the control of broad-leaf weeds and grasses, better fungicides are needed to supplement breeding work for the control of foliar rice diseases more effective seed-treatment chemicals are needed for rice sown in water and satisfactory chemical repellants are needed to prevent losses from bird pests on maturing rice. 

The results of this test demonstrated that the diamides of the Ci4 and higher saturated fatty acids were water repellents. On the other hand, the unsaturated oleic acid derivatives enhanced hydrophilicity. 

A listing of compounds evaluated in the laboratory as cockroach repellents summarizes 872 synthetic compounds out of 901 bioassayed from 1953 to 1974 (43). Fencholic acid [512-77-6] (3-isopropyl-l-methylcyclopentanecarboxylic acid) has been used as a standard repellent in tests conducted by placing 20 cockroaches in a glass crystallizing dish without food and water and offering them a choice of two cardboard shelters, one of which was treated with 1 or 2 ml, of a 1% solution of the candidate in acetone. Counts were made daily for seven days. 

TABLE 2. Water Repellency and Water Slip Testing Results for Selected Polymers"... 

AATCC methods for determining water repellency are AATCC 22 (spray test) and AATCC 70 (tumble jar dynamic absorption test). In the spray test, water is sprayed against the taut surface of the test specimen to produce a wetted pattern the size of which depends on the repellency of the fabric. Evaluation is by comparing the pattern with a series of patterns on a standard chart. The latter method evaluates the percentage by weight of water absorbed by a sample after dynamic exposure to water for a specified period of time. 

Oxadiazole derivatives have been tested in the textile industry as antistatic agents for textile finishes,232,233 thermally stable polymers,82, 234,235 fluorescent whiteners,236 oil and water repellents on cotton and wool,237 and blue dyes for polyesters and polyamides.238 Oxadiazole merocyanine dyes have been patented as photosensitizers for silver halide emulsions.239... 

Semi-quantitative results may be obtained by the use of the Yagoda confined-spot-test papers (Schleicher and Schuell, U.S.A., Nos. 211Y and 597Y) these are prepared with a chemically inert, water-repelling barrier which constricts the spot reaction to a uniform area of fixed dimensions. 

TABLE 1. Water/alcohol and oil repellency testing of fabrics modified with perfluoroacrylate monomer to confer a hydrophobic/oleophobic repellent surface. 

Fabric Sample Water/Alcohol Unwashed Repellency Test 10 Wash Cycles Oil Repellency Test ... 

TABLE 3. Results of water and methylene/iodine repellency testing of polyimide films obtained by reacting 1,2,3,4-cyclobutane tetracarboxylic dianhydride with amines described in Table 1. 

Four samples of treated fabric are subjected to simulated rain for 10 min. The fabrics (placed on inclined cups and sealed at the edges) are in constant motion and the side of the fabric not exposed to the rain is subjected to a rubbing action. The repellency of the fabric is determined by the appearance of the wetted side, the amount of water absorbed by the fabric and the amount of water passing through the fabric. This test requires an elaborate special apparatus. 

CONDENSOL II protects coloured goods from any loss of rub fastness caused by water-repellent finishing. CONDENSOL II is affected by metal salt. If fairly large quantities of cross-linking agent and catalyst are to be used, preliminary trials should always be carried out to test whether the bath stability is adequate. 

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