1. An aqueous polymer dispersion based on copolymers of vinyl aromatics and conjugated aliphatic dienes, wherein said polymer dispersions have a mean particle size of from 80 to 150 nm and are obtained by free radical emulsion copolymerization of
(a) from 19.9 to 80 parts by weight of at least one vinyl aromatic compound,
(b) from 19.9 to 80 parts by weight of at least one conjugated aliphatic diene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of the monomers (a), (b), (c) and (d) always being 100,
in an aqueous medium in the presence of at least one degraded starch having an intrinsic viscosity \u03b7i of less than 0.07 dlg with the use of at least 0.9% by weight, based on the monomers used altogether, of initiators selected from peroxodisulfates, peroxosulfates, azo initiators, organic peroxides, organic hydroperoxides and hydrogen peroxide, at least 30% by weight of the initiators being initially taken together with the degraded starch in the aqueous medium and the monomers and the remaining initiators being metered into this initially taken mixture under polymerization conditions.
2. The aqueous polymer dispersion according to claim 1, which is obtained by free radical emulsion copolymerization, from 3 to 10% by weight of the monomers to be polymerized altogether being initially taken in the aqueous medium.
3. The aqueous polymer dispersion according to claim 1, wherein a degraded native starch having an intrinsic viscosity \u03b7i of from 0.02 to 0.06 dlg is used in the emulsion copolymerization.
4. The aqueous polymer dispersion according to claim 1, wherein
(a) from 19.9 to 80 parts by weight of styrene andor methylstyrene,
(b) from 19.9 to 80 parts by weight of 1,3-butadiene andor isoprene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of monomers (a), (b), (c) and (d) always being 100,
are used in the emulsion copolymerization.
5. The aqueous polymer dispersion according to claim 1, wherein
(a) from 25 to 70 parts by weight of styrene andor methylstyrene,
(b) from 25 to 70 parts by weight of 1,3-butadiene andor isoprene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of the monomers (a), (b), (c) and (d) always being 100,
are used in the emulsion copolymerization.
6. The aqueous polymer dispersion according to claim 1, wherein from 15 to 60 parts by weight of a degraded starch are used per 100 parts by weight of the monomers in the emulsion copolymerization.
7. The aqueous polymer dispersion according to claim 1, wherein the solids content is greater than 55% by weight.
8. The aqueous polymer dispersion according to claim 1, wherein the emulsion copolymerization is effected in the absence of an emulsifier andor without use of polymer seed.
9. A process for the preparation of aqueous polymer dispersions based on copolymers of vinyl aromatics and conjugated aliphatic dienes by copolymerization of the monomers in an aqueous medium in the presence of a degraded starch and of free radical initiators, wherein
(a) from 19.9 to 80 parts by weight of at least one vinyl aromatic compound,
(b) from 19.9 to 80 parts by weight of at least one conjugated aliphatic diene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of the monomers (a), (b), (c) and (d) always being 100,
are used in the free radical emulsion copolymerization, a degraded starch having an intrinsic viscosity \u03b7i of less than 0.07 dlg is used and at least 0.9% by weight, based on the monomers used altogether, of initiators selected from peroxodisulfates, peroxosulfates, azo initiators, organic peroxides, organic hydroperoxides and hydrogen peroxide is used, at least 30% by weight of the initiators initially being taken together with the degraded starch in the aqueous medium and the monomers and the remaining initiators being metered into this initially taken mixture under polymerization conditions.
10. The process according to claim 9, wherein from 3 to 10% by weight of the monomers to be polymerized altogether are initially taken in the aqueous medium.
11. The process according to claim 9, wherein a degraded native starch having an intrinsic viscosity \u03b7i of from 0.02 to 0.06 dlg is used in the emulsion copolymerization.
12. The process according to claim 9, wherein
(a) from 19.9 to 80 parts by weight of styrene andor methylstyrene,
(b) from 19.9 to 80 parts by weight of 1,3-butadiene andor isoprene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of the monomers (a), (b), (c) and (d) always being 100, are used in the emulsion copolymerization.
13. The process according to claim 9, wherein
(a) from 25 to 70 parts by weight of styrene andor methylstyrene,
(b) from 25 to 70 parts by weight of 1,3-butadiene andor isoprene,
(c) from 0.1 to 10 parts by weight of at least one ethylenically unsaturated acid and
(d) from 0 to 20 parts by weight of at least one other monoethylenically unsaturated monomer,
the sum of the parts by weight of the monomers (a), (b), (c) and (d) always being 100,
are used in the emulsion copolymerization.
14. The process according to claim 9, wherein acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, vinylsulfonic acid, acrylamidomethylpropanesulfonic acid, vinylphosphonic acid, alkali metal or ammonium salts of these acids and mixtures of the acids andor salts are used as component (c) in the monomer mixtures in the emulsion copolymerization.
15. The process according to claim 9, wherein from 15 to 60 parts by weight of a degraded starch are used per 100 parts by weight of the monomers in the emulsion copolymerization.
16. The process according to claim 9, wherein sodium persulfate, potassium persulfate, ammonium persulfate, sodium peroxodisulfate, potassium peroxodisulfate andor ammonium peroxodisulfate is used as initiator.
17. The process according to claim 9, wherein the emulsion copolymerization is effected in the absence of an emulsifier andor without use of polymer seed.
18. A binder, adhesive, size for fibers or for the production of coverings comprising the aqueous polymer dispersion according to claim 1.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A rigid core for forming a tire, which is a rigid core comprising an annular core main body provided in its outer surface with a tire molding surface portion for forming a green tire, and vulcanizing and molding the green tire between the core main body and a vulcanizing mold by being put into the vulcanizing mold together with the green tire, and which is characterized in that
the core main body is composed of a plurality of core segments divided in a circumferential direction,
the core segments comprise
first core segments having a small circumferential width and having both circumferential end surfaces as first butting surfaces, and
second core segments arranged alternately with the first core segments, having a large circumferential width and having both circumferential end surfaces as second butting surfaces,
the core main body is formed into an annular shape by butting the circumferentially adjacent first and second butting surfaces against each other, and
the first butting surface comprises
an outwardly inclined surface portion inclined so that the circumferential width increases toward the inside in a radial direction, and
a parallel surface portion connected to the radially outside of the outwardly inclined surface portion via a borderline and being parallel with a center plane in the circumferential width, of the first core segment.
2. The rigid core for forming a tire as set forth in claim 1, which is characterized in that,
in the first butting surface,
a ratio SaSO of
an area Sa of the parallel surface portion and
an outline area SO of the first butting surface surrounded by the outer outline thereof is 0.05 to 0.70.
3. The rigid core for forming a tire as set forth in claim 1, which is characterized in that,
in the first butting surface,
an angle \u03b8 of the outwardly inclined surface portion with respect to the center plane in the circumferential width is 0.01 to 3.0 degrees.
4. The rigid core for forming a tire as set forth in claim 2, which is characterized in that,
in the first butting surface,
an angle \u03b8 of the outwardly inclined surface portion with respect to the center plane in the circumferential width is 0.01 to 3.0 degrees.