What is claimed is:
1. A tool for repairing damaged threads on PVC pipe and PVC pipe fittings comprising:
an elongate shaft having a proximal end zone and an opposite distal end zone;
a handle on said proximal end zone;
a head on said distal end zone, said head including a threaded tap for forced threaded engagement with the damaged threads of the PVC pipe or PVC pipe fittings and said tap being structured and disposed to cut and reshape the damaged threads upon advancement and withdrawal of said head relative to the damaged threads by manually rotating the handle, thereby restoring the damaged threads to an operable condition.
2. The tool as recited in claim 1 wherein said threaded tap is provided on an exterior circumferential surface of said head.
3. The tool as recited in claim 2 further comprising means on said head for yielding to inwardly directed radial forces upon advancement of said threaded tap along the damaged threads.
4. The tool as recited in claim 3 wherein said means for yielding comprises a plurality of axial slots in said threaded tap.
5. The tool as recited in claim 1 wherein said handle is positioned and disposed perpendicularly relative to said shaft.
6. The tool as recited in claim 1 wherein said threaded tap is formed of hardened steel.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A process for the preparation of polybutadiene latex, in which butadiene is polymerized by a free radical emulsion polymerization reaction in the presence of initiator and, if required, dispersants and further conventional assistants, wherein the polymerization is carried out in the presence of reactive comonomers in such a way that a heat flow of 43 wattkg solids content of the polymerization mixture is not exceeded.
2. A process as claimed in claim 1, comprising a heat flow profile with:
during a first period of 10-700 minutes, a change in the heat flow per unit time of 0.01-0.5 watt(kgmin);
during a subsequent second period of 0-600 minutes, a change in the heat flow per unit time of 0.1-0.1 watt(kgmin);
during a subsequent third period of 10-1000 minutes, a change in the heat flow per unit time of <0 watt(kgmin).
3. A process as claimed in claim 1 or 2, wherein the polymerization is carried out by a semi-batch procedure in which
(a) in a first stage, a portion of butadiene and at least one portion of reactive comonomer in the form of an aqueous emulsion are initially taken with a thermal polymerization initiator and, if required, dispersants and further conventional assistants and the polymerization is initiated,
(b) in a second stage, the remaining amount of butadiene and, if required, the remaining amount of reactive comonomer are added undiluted or in the form of an aqueous emulsion, if required with dispersants and, if required, further conventional assistants, as a feed.
4. A process as claimed in claims 1 to 3, wherein the total amount of reactive comonomer is initially taken.
5. A process as claimed in any of claims 1 to 4, wherein the total amount of reactive comonomer is from 3 to 20% by weight of the total amount of monomers (butadienereactive comonomer).
6. A process as claimed in any of claims 1 to 5, wherein the reactive comonomer is styrene.
7. A polybutadiene latex, which can be prepared by a process as claimed in any of claims 1 to 6.
8. A process for the preparation of butadiene graft copolymers, in which a polybutadiene latex is prepared in the form of a grafting base by a process as claimed in any of claims 1 to 6 and
(c) in a further step, a graft layer comprising at least one vinylaromatic monomer, acrylonitrile and, if required, further ethylenically unsaturated monomers is grafted on.
9. A process as claimed in claim 8, wherein step (c) is carried out in the presence or in the absence of a molecular weight regulator.
10. A butadiene graft copolymer, which can be prepared by a process as claimed in any of claims 1 to 9.
11. An ABS molding material, comprising
(a) from 5 to 80% by weight of butadiene graft copolymers as claimed in claim 10 as component A and
(b) from 20 to 95% by weight of thermoplastic copolymers of at least one vinylaromatic monomer, acrylonitrile and, if required, further ethylenically unsaturated monomers.
12. The use of a butadiene graft copolymer as claimed in claim 10 or of a molding material as claimed in claim 11 for the production of shaped articles, films and fibers.