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Process for manufacturing a toothbrush

a manufacturing process and toothbrush technology, applied in the field of manufacturing a toothbrush, can solve the problems of children's and difficulty in handling toothbrushes by people with arthritis

Inactive Publication Date: 2002-06-20
MCNEIL PPC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Toothbrushes may be difficult to handle for several reasons.
Children may have difficulty handling toothbrushes due to the size of the child's hands.
People with arthritis also sometimes have difficulty handling toothbrushes, due to difficulty in flexing the joints in their hands.
Handicapped people may also have difficulty handling toothbrushes.
Firstly, the toothbrush is more expensive due to the use of more plastic to make the toothbrush.
Secondly, the cost of manufacture is increased because the time to cool the toothbrush increases.
EP 668140, may result in inadequate hollowing of the toothbrush handle, i.e., some portions of the previously injected polymer remain as a "mound" near the gas injection point and are not uniformly distributed against the walls of the mold.
Additionally, it may be difficult to control the flow of the gas sufficiently to prevent hollowing of the toothbrush neck.
EP 721832, may result in inadequate hollowing of the toothbrush handle.
Additionally, the process is likely to lead to a hollowing of the toothbrush neck.
Although useful, the edge gate may result in excess polymer flowing into the toothbrush mold after the gas has been injected.

Method used

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  • Process for manufacturing a toothbrush
  • Process for manufacturing a toothbrush
  • Process for manufacturing a toothbrush

Examples

Experimental program
Comparison scheme
Effect test

example 1

Gas Flow Perpendicular to the Lengthwise Direction of the Toothbrush Mold

[0022] An injection molding machine designed such that the toothbrush mold was injected with molten plastic near the base portion of the toothbrush mold, perpendicular to the lengthwise direction of the toothbrush mold, and the gas was injected at the center of the end of the base portion of the toothbrush mold, parallel to the lengthwise direction of the toothbrush mold, was used in this Example 1. The location of the gas injection port in the center of the end portion of the mold helped ensure that the gas was injected into the central region of the mold cavity. Molten polypropylene (9 grams / 75 percent by volume of the capacity of the mold cavity) was injected into the mold. Nitrogen gas was then injected into the mold cavity for about 2 to 3 seconds. The pressure of the gas at the start of the gas injection cycle was about 1724 kPa / second. The gas injection pressure was uniformly increased throughout the ga...

example 2

Gas Flow From the Center of the Base End of the Toothbrush Mold

[0024] The injection molding machine described in Example 1 was modified such that the toothbrush mold was injected with molten plastic at the center of the end of the base portion of the toothbrush mold, parallel to the lengthwise direction of the toothbrush mold. The gas injection port remained located in the center of the end of the base portion of the toothbrush mold. Molten polypropylene (9 grams / 75 percent of the capacity of the mold by volume) was injected into the mold. Nitrogen gas at an initial pressure of 1724 kPa was fed into the molten plastic for 3 seconds, with the pressure at the end of the cycle being 2070 kPa / second. The toothbrush was cooled and removed from the mold.

Results

[0025] The toothbrush made according to Example 2 was cut in half along the lengthwise direction of the handle. The handle was hollow, and the mound of residual plastic observed in the toothbrush of Example 1 was eliminated. The pr...

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Abstract

A process for manufacturing hollow handled toothbrushes is disclosed. The process includes; a) providing a toothbrush mold having a head portion, a base portion, a toothbrush cavity located between said head and end portions and having walls, an injection port for molten plastic, and a gas injection port, wherein the gas injection port is positioned in the end of the base portion of the mold so that gas is injected into the mold cavity substantially centrally thereof and in a direction parallel to the longitudinal axis of the mold; b) injecting a predetermined amount of a molten plastic into the mold cavity to partially fill the cavity; and c) injecting at least one gas through the gas injection port into the cavity to direct the molten plastic against the walls of the mold cavity.

Description

[0001] This patent relates to an improved process for manufacturing a toothbrush. More specifically, the patent relates to a process for manufacturing hollow handled toothbrushes. The process utilizes a gas which is injected from a specific location in a toothbrush mold to assist in blowing a molten plastic therethrough. The injection of the gas in a specific location results in a more efficient process for manufacturing hollow handled toothbrushes.DESCRIPTION OF THE PRIOR ART[0002] Toothbrushes are typically manufactured using an injection molding process. The injection molding process is characterized by providing a mold in the shape of the toothbrush and injecting molten plastic through a hot channel nozzle into the mold. The toothbrush is then cooled and ejected from the mold.[0003] Toothbrushes may be difficult to handle for several reasons. Children may have difficulty handling toothbrushes due to the size of the child's hands. People with arthritis also sometimes have difficu...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B29C45/26B29C45/00B29C45/17B29L22/00B29L31/42
CPCB29C45/1704B29L2031/425B29C2045/1728
Inventor MORAWSKI, LINDA MARY
Owner MCNEIL PPC INC