Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
1999-03-24
2001-08-21
Harris, Cynthia (Department: 1774)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S188000, C510S193000, C510S219000, C510S441000, C510S445000, C510S446000
Reexamination Certificate
active
06277809
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a resin granule used for washing, a method for producing the same and a method for washing resin molders or the like using the same. More particularly, the invention relates to granules consisting of resin particles, each of which is coated with a detergent component on the surface. Such granules showing excellent ability to wash a molder, e.g., injection molder or extruder, when the color or type of resin it molds is to be changed, requiring only a short time and a small quantity for any type of resin. The invention also relates to a method for producing such granules by coating the particles of the granule with a coating component by an adequate method, e.g., immersion of the particles in the coating solution, spraying the coating solution onto the particles, adsorption of the coating component on the particles. The invention also relates to a method for washing molders or the like using the same.
BACKGROUND OF THE INVENTION
In molding synthetic resin by an injection molder or extruder, the molder is washed when type of resin it molds is to be changed, with the resin that will next be molded to remove the residues of the preceding resin. However, washing a molder by such a method takes a long time, needs large quantities of wash resin, and cannot completely wash complex structures within the molder, with the result that the molded articles of the subsequent resin may be discolored, and their qualities, such astransparency, degraded.
It is very important for molding synthetic resin to reduce the quantity of wash resin and the washing time for a molder, when color or type of resin it molds is to be changed, in order to maintain or improve productivity.
In order to solve the above problems, detergents of thermoplastic resin compositions, incorporated with a detergent component, have been developed, and are used to clean a molder when type of resin it molds is changed.
For example, Japanese Laid-open Patent Application No. 124046/1993 discloses a resin composition for washing molders that mold thermoplastic resins, which comprises (a) a thermoplastic resin incorporated with (b) 1 to 20 wt. % of a sulfonic acid-based surfactant, (c) 1 to 30 wt. % of an inorganic salt or metallic hydroxide having water of crystallization, starting to be dehydrated at 100° C. or higher [e.g., Al(OH)
3
], (d) 1 to 20 wt. % of an inorganic filler. Japanese Patent Publication No. 78557/1994 discloses a resin composition for washing molders, which comprises (A) a thermoplastic resin incorporated with (B) factice, (C) slip additive and (D) non-ionic surfactant.
However, the methods for producing these compositions involve problems. For example, it is disclosed that the method for producing the former composition mixes a molten thermoplastic resin with one or more essential components and auxiliary components, also molten, by a kneader such as monoaxial or biaxial extruder. As a result, each particle of the composition contains the detergent component deep inside. For the latter composition, it is disclosed that the thermoplastic resin A is mixed with the other components A to D by a tumbler or high-speed mixer and the mixture is kneaded by an extruder. These detergents proposed so far have been produced by the methods, which fall into the category of kneading.
As described above, these detergents contain a detergent component dispersed inside the detergent particles. As a result, it takes a long time for the detergent component to diffuse to the particle surface during the washing step, even though large quantities of the expensive component being incorporated into the resin. It covers only part of the particle surface, even when it diffuses to the surface. Use of such a detergent needs a long washing time and a large quantity of the resin to be molded subsequently. Therefore, there is increased need for a detergent that can avoid these problems.
BRIEF SUMMARY OF THE INVENTION
It is the objects of the present invention to provide a resin granule which is able to wash molders, e.g., injection molder and extruder, in a shorter time and in a smaller quantity than is currently available, to provide a method for efficiently producing the same, and also to provide a method for washing resin molders or the like using the same.
The applicants of the present invention have found, after extensively studying to solve the above problems involved in the conventional detergents for washing injection molder and extruder, that the above problems can be solved by the use of resin granule whose particles are coated thinly with a detergent component on the surface, reaching the present invention.
The first objective of the present invention is to provide a resin granule for washing molders or the like, which is composed of resin particles and a detergent component, wherein each of the resin particles is covered with the detergent component on the surface.
The second objective of the present invention is to provide a method for producing the resin granule for washing molders or the like, wherein the resin granule is brought into contact with the detergent component for a sufficient time so that the external surface of the former is coated with the latter by at least one of the processes selected from the group consisting of:
(a) immersion of the resin granule in a solution of the detergent component,
(b) spraying a solution of the detergent component onto the resin granule,
(c) mixing the resin granule with a solution of the detergent component under no heating, and
(d) adsorption of the detergent component vapor on the external surface of the resin granule,
and then the resin granule coated with the detergent component is separated.
The third objective of the present invention is to provide a method for washing resin molders or the like using the above resin granule.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described concretely, below.
The resin granule of the present invention for washing molders or the like is composed of resin particles and a detergent component, wherein the external surface of each particle is coated with the detergent component. The resin granule is produced by a mixer/kneader, and the granule can take a variety of shapes, e.g., spherical, cylindrical, angular, marble-like, sheet-like and flaky. The type of resin for the resin granule is not limited, and can be thermoplastic or thermosetting. Concretely, the resin useful for the present invention includes, but is not limited to, polyolefins, e.g., high-density polyethylene, low-density polyethylene, straight-chain, low-density polyethylene, polypropylene, polybutene and polymethyl pentene; styrene-based resins, e.g., polystyrene, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, methyl methacrylate-styrene (MS) resin, and methyl methacrylate-butadiene-styrene (MBS) resin; acryl-based resins, e.g., methyl polymethacrylate (PMMA) and polyacrylonitrile (PAN); vinyl-based resins, e.g., polyvinyl chloride, polyvinyl acetate and polyvinylidene chloride; and EPDM, methyl ethylene methaccrylate (EMMA), polyamide, polyacetal (POM), polycarbonate (PC), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyethylene terephthalate (PETP), polybutylene terephthalate (PBTP), polyether imide (PEI), polyetheretherketone (PEEK), fluorine-based resins, silicon-based resins, epoxy resins and decomposable resins. They can be used individually or in combination. The resin granule may be powdery or pellets of relatively large size. It can be produced by cutting, e.g., sheet-cut, strand-cut, hot cut in air or hot cut in water using a kneading device, e.g., monoaxial or multi-axial extruder, continuous mixer, Banbury mixer, internal mixer, Co-kneader, high-pressure kneader, or open two-roll device. Size of the granule is not limited, the efficient size for the present invention being 0.5 to 10 mm on the average, preferably 1 to 5 mm, as the longest dimension of each particle. It is particularly preferable that the particles have a specific size distribution fo
Garrett Dawn L.
Harris Cynthia
Schneller Marina V.
Venable
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