Method of injection molding articles with selective concentrations or gradients of materials
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B29C-045/14
출원번호
US-0177103
(1994-01-03)
발명자
/ 주소
Fitzgibbon Denise R. (Hockessin DE)
출원인 / 주소
Metton America, Inc. (Abingdon VA 02)
인용정보
피인용 횟수 :
13인용 특허 :
0
초록▼
The invention provides an improved process for molding articles having a bulk material and an auxiliary material, such as an additive, a comonomer, or a catalyst, present in the bulk material as a fixed concentration strip or in a concentration gradient in the direction from the surface to the inter
The invention provides an improved process for molding articles having a bulk material and an auxiliary material, such as an additive, a comonomer, or a catalyst, present in the bulk material as a fixed concentration strip or in a concentration gradient in the direction from the surface to the interior. The invention is especially useful for concentrating surface-enhancing auxiliary materials at the surface of an article without wasting the auxiliary material in the interior of the article where it provides minimal value. This invention is also applicable to concentrating an interior-enhancing auxiliary material in the interior of the article without degrading surface sensitive properties. The method for manufacturing an as-molded article having a bulk material and an auxiliary material provided therein generally comprises injecting a moldable bulk material composition into a mold with an essentially laminar flow profile such that the earlier injected material will reside at the surface of the mold (i.e., the surface of the manufactured article) and the later injected material will constitute the interior portion of the article, and controlling the injection of the auxiliary material during filling of the mold with the bulk material to direct the auxiliary material to a desired location within the bulk material.
대표청구항▼
A process for making an as-molded article of manufacture composed essentially of a solid resin, wherein a resin-modifying auxiliary material is concentrated in the surface portion of the article, comprising the following steps: a) injecting into the cavity of a mold over a period of time a liquid th
A process for making an as-molded article of manufacture composed essentially of a solid resin, wherein a resin-modifying auxiliary material is concentrated in the surface portion of the article, comprising the following steps: a) injecting into the cavity of a mold over a period of time a liquid that will form a solid resin in the mold, said injecting being conducted in a laminar fashion so that the liquid first coats the wall of the mold cavity, and continuing said injecting until the cavity is substantially full; b) altering the composition of the injection liquid during said period of injection, without interrupting the injection, by initially incorporating an auxiliary material in the liquid at a first concentration level, and subsequently reducing the concentration of said auxiliary material prior to the end of the injection period, so that the auxiliary material is more concentrated in the portion of the liquid that coats the wall of the mold than it is in the portion of the liquid that is in the center of the mold cavity, said auxiliary material being a material that modifies a property of the resin, and said auxiliary material being mixed into the injection liquid at the beginning of step (a) in an amount that is sufficient to change said property of the resin at the surface of the as-molded article, but which is no more than 50 volume percent of the mixture of liquid and auxiliary material; and c) after the injected liquid forms a solid resin, removing the resultant article from the mold. A process for making an as-molded article of manufacture composed essentially of a solid resin, wherein a resin-modifying auxiliary material is concentrated in an interior portion of the article, comprising the following steps: a) injecting into the cavity of a mold over a period of time a liquid that will form a solid resin in the mold, said injecting being conducted in a laminar fashion so that the liquid first coats the wall of the mold cavity, and continuing said injecting until the cavity is substantially full; b) at some point during the injection period, altering the composition of the injection liquid, without interrupting the injection, by incorporating a greater concentration of an auxiliary material in the liquid than was theretofore being incorporated, so that the auxiliary material is less concentrated in the portion of the liquid that coats the wall of the mold than it is in a portion of the liquid that is more toward the center of the mold cavity, said auxiliary material being a material that modifies a property of the resin, and said auxiliary material being mixed into the injection liquid at some point during step (a) in an amount that is sufficient to change said property of the resin in an interior portion of the as-molded article, but which is less than 50 volume percent of the mixture of liquid and auxiliary material; and c) after the injection liquid forms a solid resin, removing the resultant article from the mold.
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