A process for producing protective-colloid-stabilized polymers based on ethylenically unsaturated monomers in the form of water-redispersible powders, by producing aqueous dispersions of protective-colloid-stabilized polymers based on ethylenically unsaturated monomers by polymerization of one or more ethylenically unsaturated monomers in an aqueous medium and drying said dispersions in the presence of one or more drying aids. The drying aids include a) one or more inorganic salts selected from the group of alkali metal sulfates and alkali metal sulfites and b) optionally one or more water-soluble organic polymers. The inorganic salts a) are present in the aqueous dispersions of the protective-colloid-stabilized polymers based on ethylenically unsaturated monomers in dissolved form after all drying aids have been added. The inorganic salts a) are employed as drying aids to an extent of 25% by weight based on the total weight of the drying aids.

The invention relates to a method for preparing rubbers from a dispersion (1) containing the rubber, said method comprising: (a) feeding the dispersion (1), that contains the rubber, and a precipitation solution (3) into a precipitation tank (5), an aqueous suspension (9) that contains rubber particles being produced; (b) optionally sintering the rubber particles contained in the aqueous suspension (9) that contains rubber particles to form larger particles; (c) mechanically dewatering the aqueous suspension (9) that contains rubber particles, rubber particles (33) that contain residual moisture and a liquid phase (35) that contains fine-particle rubber being obtained, the liquid phase (35) that contains fine-particle rubber being returned to the precipitation tank (5).

The invention relates to a method for preparing rubbers from a dispersion (1) containing the rubber, said method comprising: (a) feeding the dispersion (1), that contains the rubber, and a precipitation solution (3) into a precipitation tank (5), an aqueous suspension (9) that contains rubber particles being produced; (b) optionally sintering the rubber particles contained in the aqueous suspension (9) that contains rubber particles to form larger particles; (c) mechanically dewatering the aqueous suspension (9) that contains rubber particles, rubber particles (33) that contain residual moisture and a liquid phase (35) that contains fine-particle rubber being obtained, the liquid phase (35) that contains fine-particle rubber being returned to the precipitation tank (5).

A composition containing polytetrafluoroethylene and substantially free from a compound represented by Formula (3):
(H(CF.sub.2).sub.8SO.sub.3).sub.qM.sup.2
wherein M.sup.2 is H, a metal atom, NR.sup.5.sub.4 (where R.sup.5s may be the same as or different from each other and are each H or an organic group having 1 to 10 carbon atoms), an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent, and q is 1 or 2. Also disclosed is a molded boy including the composition.

A composition containing polytetrafluoroethylene and substantially free from a compound represented by Formula (3):
(H(CF.sub.2).sub.8SO.sub.3).sub.qM.sup.2
wherein M.sup.2 is H, a metal atom, NR.sup.5.sub.4 (where R.sup.5s may be the same as or different from each other and are each H or an organic group having 1 to 10 carbon atoms), an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent, and q is 1 or 2. Also disclosed is a molded boy including the composition.

Provided are a water-absorbent resin composition that has high water-blocking ability as well as excellent decomposition ability and can be suitably used for a water-blocking material; and a water-blocking material comprising the composition.

The water-absorbent resin composition of the present invention comprises water-absorbent resin particles and a chelating agent, the chelating agent having an iron(III) chelate stability constant (log K.sub.ML) of 19.0 or more and 24.0 or less, and the water-absorbent resin composition having a 30-second swelling height of 6.0 mm or more. The water-absorbent resin composition of the present invention has high water-blocking ability as well as excellent decomposition ability and can be suitably used for a water-blocking material.

Provided are a water-absorbent resin composition that has high water-blocking ability as well as excellent decomposition ability and can be suitably used for a water-blocking material; and a water-blocking material comprising the composition.

The water-absorbent resin composition of the present invention comprises water-absorbent resin particles and a chelating agent, the chelating agent having an iron(III) chelate stability constant (log K.sub.ML) of 19.0 or more and 24.0 or less, and the water-absorbent resin composition having a 30-second swelling height of 6.0 mm or more. The water-absorbent resin composition of the present invention has high water-blocking ability as well as excellent decomposition ability and can be suitably used for a water-blocking material.