Fadable Multifunctional Monofilament Having a Core-Shell Structure

The invention relates to a fadable multifunctional monofilament. More particularly, the present invention relates to a fadable multifunctional monofilament having a core-shell structure comprising an active substance and/or a functional filler. The present invention also relates to a method for preparing the monofilament material, and a use of the monofilament material in a brush material, such as a toothbrush.

In daily life, a toothbrush with fadable brush filaments can timely remind people to replace the toothbrush, which is beneficial to improving oral health. However, a brush filament with only a single fadable function cannot meet the consumer's needs. Multifunctional brush filaments that incorporate functional fillers (such as aluminum flakes) or active substances (such as NaF) into toothbrush filaments and have superimposed fading function are becoming increasingly popular among consumers.

At present, one of the common techniques for preparing fadable monofilaments is realized by a dyeing process, while the dyeing process will cause the monofilaments added with functional fillers or active substances to lose part of the functional fillers or active substances, and it is difficult to obtain fadable multifunctional monofilaments with excellent comprehensive performance.

The inventors have unexpectedly found that by providing a fadable multifunctional monofilament having a core-shell structure comprising a functional filler or an active substance, and by adding the functional filler or the active substance only in the core layer, and by specifically defining the thickness parameter of the shell layer, such a monofilament having a core-shell structure can significantly reduce the loss of the functional filler or the active substance in the dyeing process, so that the multifunctional monofilament could have excellent comprehensive multifunctional characteristics during use.

The present invention provides a fadable multifunctional monofilament having a core-shell structure, the core-shell structure consists of a core layer and a shell layer, wherein the core layer of the multifunctional monofilament comprises an active substance(s) or a functional filler(s), and the multifunctional monofilament as a whole comprises a dye(s), and a fading effect is realised by means of gradual release of the dye during the use of the multifunctional monofilament, characterized in that, the thickness of the shell layer of the multifunctional monofilament is greater than or equal to 10 μm.

The present invention also provides a method for preparing the polymeric material monofilament as described above, comprising the following steps of:

Except in the examples, or where otherwise expressly indicated, all numbers in this description indicating amounts of material or reaction conditions, physical properties of materials, and/or use are to be understood as optionally modified by a word “about.”

All amounts are by weight of the composition unless otherwise specified.

It should be noted that any specific upper value may be associated with any specific lower value when specifying any numerical range.

For the avoidance of doubt, the word “comprising” is intended to mean “including,” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive.

The disclosure of the invention found herein is considered to cover all embodiments in which the claims are found to be multiply dependent on one another, regardless of the fact that the claims may be found to be free of multiple dependencies or redundancy.

Where a feature is disclosed with respect to a particular aspect of the invention, such as a composition of the invention, such disclosure is also considered applicable, mutatis mutandis, to any other aspect of the invention, such as a method of the invention.

Also, the indefinite articles “a” and “an” preceding an element or component of the invention are intended to be nonrestrictive regarding the number of instances (i.e. occurrences) of the element or component. Therefore “a” or “an” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.

The monofilaments having a core-shell structure can be prepared using techniques well known in the art.

According to one embodiment of the present invention, a monofilament having a core-shell structure may be prepared by a conventional spinning co-extrusion process. Specifically:

According to the present invention, the shell layer thickness of the multifunctional monofilament having a core-shell structure is at least 10 μm. In a preferred embodiment of the present invention, the shell layer thickness of the monofilament having a core-shell structure is equal to and larger than 20 μm; the upper limit of the shell thickness of the monofilament is limited only by the conditions of the preparation process. In a more preferred embodiment of the present invention, the shell layer thickness of the monofilament having the core-shell structure is from 20 μm to 100 μm, most preferably from 20 μm to 40 μm.

Dyeing of Multifunctional Monofilaments with a Core-Shell Structure:

After the multifunctional monofilament having the core-shell structure is obtained, it can be dyed by a dyeing process known in the art.

According to an embodiment of the present invention, the obtained multifunctional monofilament having a core-shell structure is dyed by a dyeing process: immersing the tow of the multifunctional monofilament having a core-shell structure in a dyeing solution, adjusting the pH range of the dyeing solution to from 1 to 7, and then heating the dyeing solution to a temperature such as from 80° C. to 100° C. while maintaining the temperature for 10 to 60 min for dyeing; after dyeing is finished, cooling and washing the monofilament to obtain a dyed monofilament. Finally, the dyed monofilament is subjected to post-treatment such as drying to obtain a finished fadable multifunctional monofilament having a core-shell structure.

For dyes that can be used in the dyeing process of the present invention, the basic requirement is that the dye used is a food grade dye.

According to a preferred embodiment of the present invention, the food grade dye comprises an acidic water-soluble/disperse dyes.

According to a further preferred embodiment of the present invention, the acidic water-soluble/disperse dye is selected from the following types: methylene blue dye; indigo dyes and the like, wherein the indigo dyes include but are not limited to, indigo blue, indigo violet, indigo red, indigo orange; the disperse dye includes, but is not limited to, disperse orange, disperse blue, disperse yellow, disperse red; or disperse black, disperse green, or disperse violet obtained by any ratio combination of disperse orange, disperse blue, disperse yellow, and disperse red thereof, and further includes anthraquinone dye; and the plant-based natural dye which includes, but is not limited to, curcumin, anthocyanin, curcumin, shikonin, alizarin red and betalain, as well as eco-friendly C.I. acid red 249, C.I. acid violet 54, C.I. acid blue 324 dye and the like.

According to a particularly preferred embodiment of the present invention, indigo dyes useful in the present invention include, but are not limited to, indigo blue and its aluminum lakes, sodium indigo disulfonate. According to a particularly preferred embodiment of the present invention, the plant-based natural dyes useful in the present invention include, but are not limited to, curcumin, anthocyanin, shikonin, alizarin red, betalain, and the like.

In principle, there is no particular limitation on the material for preparing the multifunctional monofilament of the present invention, and the common materials for preparing the monofilament in the art can be used in the preparation of the monofilament of the present invention.

According to an embodiment of the present invention, the base resin of the multifunctional monofilament useful in the present application includes polyamide (nylon), polyester, etc.

One exemplary type of the base resin that may be used in the present invention is polyamide or commonly known nylon.

The polyamides useful in the present invention have a linear backbone which can be produced by reacting a dicarboxylic acid with a diamine to form a linear condensed polyamide. Non-limiting examples of dicarboxylic acids include C6 to C12 aliphatic dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and non-limiting examples of diamines include linear aliphatic or cycloaliphatic diamines such as ethylenediamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, isophorone diamine, and 1,4-cyclohexanebis (methylamine), decanediamine, and non-limiting examples of diamines can also include linear aromatic diamines such as phenylenediamine and benzidine. Polyamides useful in the present invention may also be produced by the reaction of amino-containing carboxylic acid compounds or lactams thereof. Non-limiting examples of amino-containing carboxylic acid compounds include C6 to C12 aliphatic terminal aminocarboxylic acid compounds such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid.

Exemplary base resin polyamides include PA612, PA610, PA512, PA510, PA6, PA66, PA46, PA1010, PA11, PA12, or mixtures thereof according to well-known nomenclature in the art for polyamide materials.

In a particularly preferred embodiment, the base resin employed is PA612, such as nylon PA612 Zytel® 151 NC010 available from Celanese.

Another class of exemplary base resins useful in the present invention is polyester.

Non-limiting examples of polyester(s) include the reaction product of terephthalic acid and ethylene glycol, i.e., polyethylene terephthalate (PET), and similarly, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT). In addition, various modified polyesters may also be used in the present invention, and non-limiting examples thereof include: polybutylene succinate (PBS), polylactic acid (PLA), polys-caprolactone (PCL), poly3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV), etc. Copolyesters include, for example, polybutylene adipate/terephthalate (PBAT), polybutylene sebacate/adipate (PBSA), co-hydroxyalkanoates, and the like.

Exemplary representative of polyesters useful in the present invention include PET, PBT, PTT, etc.

Exemplary actives that may be used in the present invention include sodium fluoride, tea polyphenols, Azadirachta indica saponin, clove oil, and the like.

Sodium fluoride is a well-known anticaries compound that has long been used in toothpaste products to provide corresponding technical effects.

According to an embodiment of the present invention, sodium fluoride NaF is added to the core layer of the multifunctional monofilament having a core-shell structure as an active used in the present invention.

Commercially available sodium fluoride products are all useful in the present invention. The size of the sodium fluoride particles does not exceed the diameter of the monofilament.

Exemplary other common actives that may be used in the present invention according to embodiments of the present invention include tea polyphenols, Azadirachta indica saponin, clove oil, and the like, wherein:

Tea polyphenols: Tea polyphenols are an extract of tea leaves. The tea polyphenol has a high free hydroxyl content and can be combined with salivary protease to improve bacterial reproduction caused by protein precipitation in the oral cavity; meanwhile, the tea polyphenol also has an obvious plant antibiotic effect and can improve oral inflammation.

Commercially available tea polyphenol products are useful in the present invention, for example, available from KOEI, Dayang, Wuhan Fortuna, Parchem, etc.

Azadirachta indica Saponin: Azadirachta indica saponin eliminates free radicals and has antioxidant effects. It also inhibits various fungi and bacteria, serving as an antibacterial, an anti-inflammatory agent and an anti-plaque agent,

For example, the commercially available Azadirachta indica Saponin products can be purchased from Chengdu Symphs Biotechnology, Hubei Guango Biotechnology, Shanghai Research Biotechnology, etc.

clove oil: clove oil is an oil extracted from clove leaves, has a certain medicinal value, and has analgesic, antibacterial and anti-inflammatory effects, and can be used for oral pain relief, anti-inflammatory and caries prevention.

All commercially available clove oils can be used in the present invention, for example, the clove oils can be purchased from Shanghai source leaf biotechnology Co., Ltd., Nanjing chemical reagent Co., Ltd., etc.

Functional fillers may be used in the preparation of the core layers of the multifunctional monofilaments of the present invention having a core-shell structure to provide particular functional technical effects; such as imparting a shiny effect to the monofilaments.

Exemplary functional fillers useful in the present invention include aluminum flakes, mica flakes, and the like.

Aluminum flakes: a tiny sized aluminum flakes can be used to bring a flickering aesthetic effect to the brush filaments.

In principle, the use of the aluminum flakes is not particularly limited as long as it can be suitably incorporated into the monofilament according to the present invention.

According to one embodiment of the present invention, the aluminum flakes suitable for use in the present invention have, for example, a thickness of 10-30 μm and a length/width (i.e., length or width) of 20-140 μm. Commercially available aluminum flakes can be used in the present invention. For example, the aluminum flakes are commercially available from Hefei Keji, Zhongti Xincai, Avient, etc.

According to another embodiment of the present invention, the mica flakes may also be used to prepare a monofilament material having an aesthetic effect similar to that of flashing.

The use of the mica is not particularly limited in principle, as long as it can be suitably incorporated into the brush filaments.