Multi-strand filament

Abstract

Multi-strand filament for the manufacture of bristles for an applicator, comprising at least two strands which are firmly connected to one another, wherein a first strand only partially surrounds at least one second strand in the circumferential direction thereof.

Description

[0001] MULTI-STRAND FILAMENT

[0002] FIELD OF INVENTION

[0003] The invention relates to a multi-strand filament according to the generic term of claim 1 .

[0004] TECHNICAL BACKGROUND

[0005] Filaments - especially 3D-printing filaments - are available in di f ferent materials , surface structures , with di f ferent coatings and can be used in mixtures in order to combine or to achieve speci fic properties . There are also co-extruded (bimaterial ) filaments known . Co-extrusion of two di f ferent plastic materials are known and is used in the state of the art .

[0006] However, the materials currently available are often unsuitable or unsatis factory for providing the properties required for bristles of applicators ; especially cosmetic or dental applicators .

[0007] OBJECT OF THE INVENTION

[0008] Accordingly, it is the obj ect of the invention to provide a material with suitable and satis factory properties for bristles of an applicator .

[0009] SOLUTION ACCORDING TO THE INVENTION

[0010] A solution to this problem is provided by the main claim .

[0011] For this purpose , a multi-strand filament for the manufacture of bristles for an applicator is proposed . Said filament comprises at least two strands which are firmly connected to one another, so that they do not separate during processing into bristles and in applicator use and - preferably - that they do not separate ( fully or in tip region only) by bristle trimming operations , as grinding .

[0012] The filament is characteri zed in that a first strand only partially surrounds at least one second strand in the circumferential direction thereof . The at least one second strand exhibits an open section or open sections that are not surrounded by the first strand . This type of arrangement allows the resulting filament to have suitable and satis factory properties for bristles of an applicator . With the filaments described in this invention, it is possible to combine di f ferent properties in one fiber . Preferably, the properties of such a hybrid filament , will on one hand have proper sti f fness and retention for precise applications and good absorbing properties to transport liquids / bulks .

[0013] PREFERRED DESIGN OPTIONS OF THE INVENTION

[0014] A preferred design option is that the first strand is a support strand, consists of a first material which imparts to the fibre at least the maj or part of its bend-recovery capacity, said first material preferably not exhibiting capillary action . This first strand preferably gives stability to the whole filament . It is preferred that this first material is Polyamide ( PA) , Polyethylene terephthalate ( PET ) , Polybutylene terephthalate ( PET ) , Polypropylene ( PP ) , Polyethylene ( PE ) or another thermoplastic material . It is also preferred that the at least one second strand consists of a second material which exhibits a capillary action by means of which it can store , transport and / or release a liquid . Therefore , a liquid like a cosmetic mass or the like can be stored and released easily, but the filament also has the necessary sti f fness and stability - since the second strand has no substantial or in most cases at least only 1 / 10 or at least only 1 / 4 of the bend recovery of the first strand . In most cases the material used for the first strand is - at least essentially - free from any capillary action in regard to the material to be applied, for example cosmetics or a water- or alcohol or oil-based fluid agent .

[0015] It is furthermore preferred that the second material consists of a plurality of thin fibres twisted or stranded together, each ideally consisting of a PET , PBT or PA in pure form or a mixture thereof , or each consisting of a natural fibre material such as cotton or silk . Therefore , a variety of properties can be achieved with the filament according to the invention .

[0016] It is also preferred that the structure of the multi-stranded filament exhibits a longitudinal orientation such as occurs when the multi-stranded filament is stretched together, preferably by a factor of 2 to 4 . "Stretched together" means that the filament is pulled into length in the direction of the longitudinal axis under plastic deformation .

[0017] It is also preferred that the at least one second strand is bonded to the first strand, and preferably has a microstructure such as is produced when the first strand and the at least one second strand are co-extruded . The process of co-extrusion is the preferable manufacturing process of the filament according to the invention, because it achieves the desired result and properties as well as the cost-ef ficient way of production .

[0018] It is also preferred that the filament has two second strands whose diameter is in each case smaller by at least a factor of 2 , preferably by at least a factor of 4 , than the diameter of the sheath cylinder of the first strand . These dimensions are responsible for suitable and satis factory properties for bristles of an applicator .

[0019] It is also preferred that the filament has two second strands which lie opposite to each other on both sides of the central longitudinal axis of the first strand . This arrangement is responsible for suitable and satis factory properties for bristles of an applicator .

[0020] It is also preferred that the filament has - preferably two - at least one second strand, the circumference of which is enclosed by the first strand to at least 60 % and preferably to a maximum of 80 % . These dimensions are responsible for suitable and satis factory properties for bristles of an applicator .

[0021] FIGURE LIST

[0022] Figure 1 shows a preferred embodiment of the multi-strand filament in cut front view .

[0023] PREFERRED EMBODIMENT Fig . 1 shows a preferred embodiment of the multi-strand filament 1 . This filament 1 is preferably used for the manufacture of bristles for an applicator .

[0024] The filament 1 comprises at least two strands - a first strand 2a and at least one second strand 2b - which are firmly connected to one another . The first strand 2a only partially surrounds the at least one second strand 2b in the circumferential direction thereof . It is also possible that the first strand 2a comprises openings like windows or cutouts .

[0025] In the shown preferred embodiment , the filament 1 comprises two second strands 2b . Yet , it is also possible in an many cases even preferable that a filament 1 according to the invention comprises more second strands . It is sometimes preferable that a filament 1 comprises up to 400 second strands .

[0026] According to the invention the coextrusion preferably should be tuned that way, that materials of the first strand 2a and the at least one second strand 2b are brought into a particular close contact so that the contact surface fuses or so that both contacting surfaces are fully glued / bonded together . In some cases , the "bonding" is accomplished that way that a molten portion of the plastic material of the first strand intrudes into (below) the surface of the capillary material of the at least one second strand and solidi fies there .

[0027] In addition, or instead the interconnection between the first strand 2a and the second strand 2b is accomplished or supported that way that the first strand 2a partially clasps the circumference of the second strand, mostly for more than 190 ° better for more than 210 ° , seen in circumferential direction .

[0028] The first strand 2a is a support strand and consists of a first material which imparts to the fibre at least the maj or part of its bend-recovery capacity, said first material preferably not exhibiting capillary action .

[0029] The second strands 2b consist of a second material which exhibits a capillary action by means of which it can store , transport and / or release a liquid . Said second material consists of a plurality of thin fibres twisted or stranded together, each ideally consisting of a PET , PBT or PA in pure form or a mixture thereof , or each consisting of a natural fibre material . In Fig . 1 , there are many more fibres shown inside each of the second strands 2b . Those are preferably single fibres 3 of the natural material or plastic fibres that are surrounded by another material . Overall , the second strand 2 preferably is defined as a plurality of individual filaments . Those filaments are preferably twisted or otherwise woven together .

[0030] The second strands 2b are preferably bonded to the first strand 2a, and preferably has a microstructure such as is produced when the first strand 2a and the at least one second strand 2b are co-extruded .

[0031] The filament 1 shown in Fig . 1 has two second strands 2b whose diameter is in each case smaller by at least a factor of 3 , preferably by at least a factor of 4 , than the diameter of the sheath cylinder of the first strand 2a . The diameter of the sheath cylinder of the first strand 2a is preferably in a range between 0 . 1 to 0 . 5 mm, while the diameter of the single fibres 3 is preferably between 0 . 01 mm to 0 . 05 mm .

[0032] Said sheath cylinder of the first strand 2a preferably is ( seen from outside ) a not necessarily constantly but continuously convex structure with some punctual exemptions in the shape of the cavities that are formed by the outer surface of the second strands 2b . The diameter of this sheath cylinder is preferably the diameter of the smallest cylinder with a round cross-section that can enclose said sheath cylinder, the protruding second strand ( s ) 2b out of consideration .

[0033] The shown filament 1 preferably has two second strands 2b which lie opposite to each other on both sides of the central longitudinal axis of the first strand 2a . Furthermore , the filament 1 has preferably two second strands 2b, the circumference of which is enclosed by the first strand 2a to at least 60 % and preferably to a maximum of 80 % .

[0034] REFERENCE LIST

[0035] 1 Multi-strand filament

[0036] 2a First strand

[0037] 2b Second strand 3 Single fibre

Claims

PATENT CLAIMS1. Multi-strand filament (1) for the manufacture of bristles for an applicator, comprising at least two strands (2a, 2b) which are firmly connected to one another, characterized in that a first strand (2a) only partially surrounds at least one second strand (2b) in the circumferential direction thereof .

2. Multi-strand filament (1) according to claim 1, characterized in that the first strand (2a) is a support strand, consists of a first material which imparts to the filament at least the major part of its bend-recovery capacity, said first material preferably not exhibiting capillary action.

3. Multi-stranded filament (1) according to claim 1 or 2, characterized in that the at least one second strand (2b) consists of a second material which exhibits a capillary action by means of which it can store, transport and / or release a liquid.

4. Multi-strand filament (1) according to claim 3, characterized in that the second material consists of a plurality of thin fibres (3) twisted or stranded together, each ideally consisting of a PET, PBT or PA in pure form or a mixture thereof, or each consisting of a natural fibre material .

5. Multi-stranded filament (1) according to one of the preceding claims, characterized in that the structure of the multi-stranded filament (1) exhibits a longitudinalorientation such as occurs when the multi-stranded filament(1) is stretched together, preferably by a factor of 2 to4.

6. Multi-strand filament (1) according to any one of the preceding claims, characterized in that the at least one second strand (2b) is bonded to the first strand (2a) , and preferably has a microstructure such as is produced when the first strand (2a) and the at least one second strand (2b) are co-extruded.

7. Multi-strand filament (1) according to one of the preceding claims, characterized in that the filament (1) has two second strands (2b) whose diameter is in each case smaller by at least a factor of 3, preferably by at least a factor of 4, than the diameter of the sheath cylinder of the first strand (2a) .

8. Multi-strand filament (1) according to one of the preceding claims, characterized in that the filament (1) has two second strands (2b) which lie opposite to each other on both sides of the central longitudinal axis of the first strand (2a) .

9. Multi-strand filament (1) according to one of the preceding claims, characterized in that the filament (1) has - preferably two - at least one second strand (2b) , the circumference of which is enclosed by the first strand (2a) to at least 60 % and preferably to a maximum of 80 %.

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