Adhesive polymer latex

An aqueous based pressure sensitive adhesive having improved shear properties comprising a latex of a polymer having a Tg less than about 0.degree. C., formed by emulsion polymerizing a monomeric mixture selected from the group comprising:

• (a)
• (i) from about 60-99.5 weight percent of a C.sub.1-8 alkyl or alkanol ester of acrylic or methacrylic acid;
• or a mixture thereof and
• (ii) from 0.5 to about 40 weight percent of a C.sub.3-9 ethylenically unsaturated acid;
• and
• (iii) from 0 up to about 5 weight percent of an amide of a C.sub.3-9 ethylenically unsaturated acid which amide may be unsubstituted or substituted at the nitrogen atom by a C.sub.1-8 alkyl or alkanol radical;
• a C.sub.3-9 ethylenically unsaturated aldehyde;
• or an anhydride of a C.sub.4-8 ethylenically unsaturated dicarboxylic acid;
• or a mixture thereof;
• (b)
• (i) from about 0 to about 60 weight percent of a vinyl aromatic monomer which may be unsubstituted or substituted by a C.sub.1-4 alkyl radical or a chlorine or bromine atom;
• (ii) from 40 to 99 weight percent of a mixture comprising 100 to 50 weight percent of a C.sub.4-8 conjugated diolefin and 0 to 50 weight percent of a C.sub.1-8 alkyl or alkanol, or a C.sub.2-8 alkenyl or alkenol ester of a C.sub.3-9 ethylenically unsaturated acid;
• (iii) from about 0.5 to 10 weight percent of a C.sub.3-9 ethylenically unsaturated acid;
• and
• (iv) from 0 up to about 5 weight percent of an amide of a C.sub.3-9 ethylenically unsaturated acid which amide may be unsubstituted or substituted at the nitrogen atom by a C.sub.1-8 alkyl or alkanol radical;
• a C.sub.3-9 ethylenically unsaturated aldehyde;
• or an anhydride of a C.sub.4-8 ethylenically unsaturated dicarboxylic acid;
• or a mixture thereof;
• and
• (c)
• (i) from about 1 to about 40 weight percent of a C.sub.2-4 monoolefin monomer;
• (ii) from about 60 to 99.5 weight percent of a C.sub.1-8 alkyl or alkanol ester of a C.sub.3-12 ethylenically unsaturated carboxylic acid or a C.sub.2-8 alkenyl or alkenol ester of a C.sub.1-12 saturated carboxylic acid or a mixture thereof;
• and
• (iii) from about 0.5 to 10 weight percent of a C.sub.3-9 ethylenically unsaturated acid;
• and
• (iv) from 0 up to about 5 weight percent of an amide of a C.sub.3--9 ethylenically unsaturated acid which amide may be unsubstituted or substituted at the nitrogen atom by a C.sub.1-8 alkyl or alkanol radical;
• a C.sub.3-9 ethylenically unsaturated aldehyde;
• or an anhydride of a C.sub.4-8 ethylenically unsaturated dicarboxylic acid or a mixture thereof;
• which has been adjusted to a pH of equal to or greater than about 6 with an agent selected from hydroxides and salts of lithium, sodium, potassium and a mixture thereof.