Abstract Mold and core rod combination for forming a plastic parison for stretch/blowing into a plastic bottle comprising a core rod with an end mated to the mold so as to permit formation of a parison with a flat on the bottom and having a sharp taper from said flat to the sidewall of the parison. The core rod is preferably shaped to include a shoulder having a substantially straight outer wall at the mouth end of the parison mold, and constructed and arranged with the mold to permit deposit of additional plastic at the inner wall of the shoulder of the parison. The design of the mated mold and core rod combination is based on the recognition that in a continuous bottle forming process a particular area of the parison can be made hotter or cooler by increasing or decreasing the thickness of that area of the parison. Parisons formed with the disclosed mold-core rod combination permit a deeper and longer stretch of the parison without tearing of deformation of the parison bottom or deformation or wrinkling at the shoulder of the finished bottle while providing essential wall strength.
A plastic parison having a bottom wall portion, a sidewall portion, a shoulder portion and a neck finish, said bottom wall portion having a flat area and there being an annular corner area joining said bottom wall and sidewall portions, said bottom wall portion having a thickness less than the thickness of said sidewall portion with there being a rapid transition from said flat of said bottom wall to said sidewall portion with said sidewall thickness being substantially constant from said annular corner area to said shoulder portion.
Claim 2
Dependent Claim
88 words
A plastic parison having a bottom wall portion, a sidewall portion, a shoulder portion and a neck finish, said bottom wall portion having a flat area and there being an annular corner area joining said bottom wall and sidewall portions, said bottom wall portion having a thickness less than the thickness of said sidewall portion with there being a rapid transition from said flat of said bottom wall to said sidewall portion with said sidewall thickness being substantially constant from said annular corner area to said shoulder portion.
Claim 3
Dependent Claim
16 words
The parison of claim 1 wherein said shoulder portion has a thickness greater than said sidewall.
Claim 4
Dependent Claim
11 words
The parison of claim 1 wherein the plastic is polyethylene terephthalate.