Stretch blow-molded stackable tumbler
The inventive drinking vessels are prepared by stretch blow-molding a preform and exhibit increased Rigidity as well as elevated, preferably relatively uniform crystallinity. A preferred method of making blow-molded stackable drinking vessels includes expanding a preform both axially and radially to make an intermediate article with a neck, a transition portion and a tumbler portion. The transition portion and neck are severed from the tumbler which is then fortified around its upper aperture which is larger than its base.
1 ) A method of making a blow-molded tumbler comprising:
(a) injection-molding a preform provided with a neck portion, a body portion and a bottom portion;
(b) stretch blow-molding the preform to form a first intermediate article therefrom wherein the preform is expanded radially as well as axially,
the first intermediate article being characterized by having a neck portion corresponding to the neck portion of the preform, a transition portion adjacent the neck portion of the first intermediate article and a tumbler portion adjacent the transition portion thereof, the tumbler portion of the first intermediate article being further characterized by having a base formed from the bottom portion of the preform and a sidewall formed from the body portion of the preform;
(c) severing the tumbler portion of the first intermediate article from its transition portion to form a second intermediate article having a base corresponding to the base of the first intermediate article and a sidewall extending upwardly therefrom to define an upper aperture, the aperture being generally larger in area than the base of the second intermediate article such that the tumbler portions are stackable; and
(d) fortifying the sidewall of the second intermediate article around the upper aperture to form the tumbler.
2 . The method according to claim 1 , further comprising the step of heating the preform after it is injection-molded and prior to blow-molding thereof.
3 . The method according to claim 1 , wherein said first intermediate article has a blow-up ratio of at least about 3 with respect to said preform.
4 . The method according to claim 3 , wherein said first intermediate article has a blow-up ratio of from about 7.5 to about 14 with respect to said preform.
5 . The method according to claim 1 , wherein said preform consists essentially of polyethylene terephthalate.
6 . The method according to claim 5 , wherein said polyethylene terephthalate has an intrinsic viscosity of from about 0.55 to about 1.05.
7 . The method according to claim 1 , wherein said preform has a weight of from about 10 grams to about 200 grams.
8 . The method according to claim 1 , wherein said tumbler has a contained volume of from about 7 to about 64 fluid oz.
9 . The method according to claim 1 , wherein said tumbler has an outward taper from its base to its upper aperture of from about 2 to about 12°.
10 . The method according to claim 1 , wherein the tumbler has a generally smooth sidewall adjacent to its fortified rim, free from thread features.
11 . The method according to claim 1 , wherein the fortified rim of the tumbler has a lateral thickness of from about 1.5 to about 10 times the thickness of the adjacent sidewall.
12 . The method according to claim 1 , wherein the tumbler sidewall has a wall caliper of generally from about 0.005 inches to about 0.1 inches.
13 . The method according to claim 1 , wherein the transition portion of the first intermediate article is provided with a circumferential groove adapted to receive a drive member for rotating the article during the step of severing the tumbler portion therefrom.
14 . The method according to claim 1 , wherein the tumbler comprises a polyethylene terephthalate polymer and lip curl is provided with a curling tool maintained at a temperature of from about 275° F. to about 350° F. around the upper aperture of the second intermediate article.
15 . The method according to claim 1 , wherein the step of fortifying the sidewall of the second intermediate article around the upper aperture comprises applying a rim-forming member to the sidewall around the upper aperture.
16 . The method according to claim 15 , wherein said rim-forming member comprises the same material as the tumbler.
17 . The method according to claim 15 , wherein said rim-forming member has U-shaped profile.
18 . The method according to claim 33 , wherein the preform is an unthreaded preform.
19 . A tumbler prepared by the method of claim 1 .
20 . The tumbler of claim 1 , wherein the tumbler is stackable.