Brushing – scrubbing – and general cleaning – Implements – Brush or broom
Reexamination Certificate
2002-04-16
2004-01-20
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Brush or broom
C015S159100, C015S167100
Reexamination Certificate
active
06678914
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is directed to thermoplastic polymer monofilaments containing a flake additive to provide monofilaments having an attractive glitter that are useful in brushes such as tooth brushes and cosmetic brushes.
Polyamide monofilaments have been used widely for bristles in brushes such as cosmetics brushes and tooth brushes. Abrasive materials have been incorporated into monofilaments that are used as bristles in tooth brushes as shown in U.S. Pat. No. 5,722,106 issued on Mar. 3, 1998 to Masterman et al. These abrasive materials are usually small particles (0.1-10 microns) but are not visible as distinct particles and are used in relatively high amounts such as 10-40% by weight of the monofilament. However, these particles do not provide an attractive glitter to the monofilaments and the monofilaments are often much more abrasive than needed.
Particles of plastic materials that are relatively thermally stable also have been incorporated into monofilaments that are used as bristles in tooth brushes to produce bristles with a structured surface that is mildly abrasive as shown in WO 97/09906 published Mar. 20, 1997. These particles of plastic materials are usually blended at a level of 5-30% by weight of the total weight of the filament and are limited to 10-50% of the diameter of the filament. These particles often cause breakage in the filament during processing.
There is a need for monofilaments that have an attractive appearance for use in tooth brushes and other brush applications that are only mildly abrasive and contain a relatively small amount of the abrasive material and are stronger and more wear resistant than those previously made. The monofilaments of the present invention provide such advantages.
SUMMARY OF THE INVENTION
A thermoplastic polymer monofilament oriented from 3.0-6.0 times its original length having a diameter of 125-600 microns and containing 0.2-5.0% by weight, based on the weight of the monofilament, of glitter particles or film particles having a particle size of 50-400 microns in its longest diameter, a thickness of 2-50 microns and having a diameter to thickness ratio of at least 2 to 1 and wherein the longest diameter of the particle is not greater than 80% of the diameter of the monofilament and that provide the monofilament with an attractive appearance. A core sheath monofilament is also part of this invention wherein the core is a thermoplastic polymer monofilament having a sheath of the same or different thermoplastic polymer containing the above described particles. These monofilaments are particularly useful in toothbrushes and cosmetic brushes.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic polymer monofilament is oriented in its original length from 3.0-6.0 times and has a diameter of 125-600 microns. The monofilament has uniformly dispersed through out glitter particles which are in the form of flakes that have a diameter in the longest dimension of 50-400 microns and a thickness of 2-50 microns and a diameter to thickness ratio of at least 2 to 1. To substantially reduce filament breakage during the manufacture of the filament, the largest diameter of the particles is not greater than 80% of the diameter of the filament. These particles provide the monofilament with an attractive appearance and often protrude through the surface of the monofilament or locally increase the diameter of the monofilament to provide mildly abrasive properties to the filament. Particles that are below 50 microns in the longest diameter can not be distinguished easily by the human eye as a distinct particle. Dyes or pigments that have a contrasting color to the glitter particles also can be added to the monofilament which adds to the attractive appearance of the monofilament. Aluminum flake particles are particularly visible in the filaments due to their high reflectance of light.
Another aspect of this invention is a core sheath monofilament in which the core is an oriented thermoplastic polymer and the sheath is the same or different thermoplastic polymer having the above described abrasive particles and optionally, can contain dyes to provide and attractive monofilament. This core sheath monofilament increases the visibility and abrasiveness of the flake particles by locating all of the flake particles at or near the surface in the sheath polymer and reduces the occurrences of strand breakage during the orientation step of the process for making such filaments since the core of the filament remains unaffected.
The monofilaments of this invention are particularly useful for the bristles of brushes, in particular tooth brushes and cosmetic brushes. Other uses of these monofilaments are as follows: paint brushes, abrasive brushes, synthetic hair for wigs, doll hair and the like.
A wide variety of thermoplastic polymers can be used to form the monofilament such as polyamides, polyesters, polyolefins, polystyrenes, styrene copolymers, fluoropolymers, polyvinylchloride, polyurethane, polyvinylidene chloride, and any compatible combination thereof.
Polyamides preferred in brush manufacturing include nylon 6, nylon 11, nylon 6,6, nylon 6,10 nylon 10,10, and nylon 6,12. Particularly preferred is nylon 6,12 (polyhexamethylene dodecanoamide) having an inherent viscosity of 1.15-1.25 measured in m-cresol according to ASTM D-2857.
Polyesters which have been found particularly well suited for bristle include polybutylene terephthalate and polyethylene terephthalate, of which the first is particularly preferred. Of the many polyolefins which can be used for bristle manufacture, polypropylene is preferred.
The glitter particles used in the monofilament are flakes that have a particle size of 50-400 microns in the longest diameter, preferably 50-150 microns, a thickness of 2-50 microns, preferably 8-20 microns and a diameter to thickness ratio of at least 2/1, preferably 5/1-10/1. The diameter to thickness ratio of the particles is important and if outside of the above range or if the diameter of the particle is greater than 80% of the diameter of the monofilament, there is a substantial increase of the occurrence of breaks in the filament as it is being oriented in the manufacturing process. The particles are present in an amount of 0.2-5.0% by weight, based on the weight of the monofilament and preferably in an amount of 0.5-2.0%. If the particles are below the size range and amount range set forth above, the glitter effects will not be noticeable to any appreciable extent. The particles are of such a material that provides a sparkle or glitter to the monofilament that improves its aesthetics for use in tooth brushes and cosmetic brushes and also provides mild abrasive properties to the monofilament which aids in the polishing action of a brush such as a tooth brush.
Preferred flake particles are flakes of aluminum and cellophane. Aluminum has excellent light reflecting properties which improves its visibility in the filaments. It is inexpensive, widely available in film and flake form and is safe to use. Aluminum flake that is approved for food contact is preferred for use in tooth brushes. Aluminum and cellophane are not melted or destroyed in the processing steps used to form the filaments. Preferably, these flakes are formed by die cutting aluminum foil or cellophane sheets. Die cutting the sheet or foil is preferred to grinding (either with or without subsequent screening ) of the foil or sheet since cutting produces substantially more regularly sized flakes than does grinding. A narrow particle size of aluminum flake or cellophane flake is much preferred since fines or large particles are detrimental to the filament. Grinding foils or sheets creates a lot of size variation.
Small flakes (below 50 microns) are not readily visible to the human eye as distinct particles and alter or dilute the color of the filament. Flakes larger than the optimum size create additional failures of the filament strands during the orientation step. Preferably, the longest flake diameter should be 40-75% of the filament diameter.
Aluminum fla
Needham Michael Christopher
Nelson Charles Fletcher
Ruffin David James
Chin Randall E.
E. I. du Pont de Nemours and Company
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