JP2008526406A - Dental tape and manufacturing method thereof - Google Patents

Abstract

The present invention is a dental floss product comprising a single tape of ultra-high molar mass polyethylene having an intrinsic viscosity of at least 5 dl / g when measured in decalin at 135 ° C., wherein the tape thickness is about 0 Relates to a dental floss product having a thickness of about 0.02 to 0.1 mm, a width of about 0.25 to 6 mm, and a tensile strength of at least 1.8 GPa. Dental floss products have very high mechanical strength, in particular tensile strength, exhibit high tear resistance, and have a low coefficient of friction. The tape can be inserted between close teeth without breaking. A further advantage of dental tape is that during cleaning with dental floss, the tape retains most of its initial strength even if the tape breaks into filaments. The invention further relates to a method for producing a single tape suitable for use in dental floss products.
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Description

Detailed Description of the Invention

  The present invention is a single tape of ultra-high molar mass polyethylene having an intrinsic viscosity of at least 5 dl / g when measured in decalin at 135 ° C., having a thickness of about 0.02 to 0.1 mm, and It relates to a dental floss product comprising a tape having a width of about 0.25 to 6 mm.

  The invention further relates to a method for producing a single tape suitable for use in dental floss products.

  Dental floss products are generally recommended as a means of treating adjacent and subgingival areas in the oral cavity to make up for lack of brushing. To clean with dental floss, put a floss product between the teeth and gently move it up and down against the surface of the teeth to remove plaque and food residues in the interdental area, including subgingival plaque. Including. Plaque is constantly formed on the surface of the tooth, and if it is not removed regularly, it can cause tooth decay and periodontal disease. During cleaning with dental floss, the floss product must be removed from the teeth by floating or crushing plaque from the tooth surface. The dental floss product therefore has dimensions that can be inserted and polished between teeth, but the strength should be sufficient to withstand the forces involved.

  The most commonly used dental floss includes a plurality of filaments made from polymers such as polyamides and polyolefins. Such multifilament floss is usually waxed to bundle the filaments together to make the floss slippery. European Patent Application EP 0339935A3 discloses a specific embodiment of a dental floss composed of multifilaments of ultra-high molecular weight polyethylene with good mechanical properties. Dental floss has been prepared by bundling a large number of stretch-oriented filaments before producing multifilaments with a tensile strength of 2.5 GPa, an elastic modulus of 90 GPA and an elongation at break of 4.1%.

  An alternative form of dental floss is dental tape, which is also optionally waxed and flavored. Although both multifilament floss products and tape floss products are said to have unique advantages and disadvantages, the choice of the optimal product also seems to be highly dependent on the user's personal preferences.

  Such a dental floss product comprising a single tape is known from EP 0 663 388 B1. In this patent specification, a single tape having a thickness of about 0.03 to 0.13 mm and a width of about 0.25 to 6.4 mm is included, the tape having a molar mass in the range of 300 to 6000 kg / mol. Describes dental floss made of high molar mass polyethylene and having a Young's modulus of the tape in the range of 0.5-10 GPa and a tensile strength in the range of 0.1-1.2 GPa. This tape has been shown to make cleaning with dental floss easier because it does not tear into filaments during use. Another advantage shown in the product is that it is not coated with a wax-like solid because it is self-lubricating. The tape used as a floss swells the polyethylene precursor tape with paraffin oil to a pseudo gel state, cools the pseudo gel to ambient temperature under controlled conditions, and gently squeezes the swollen tape to remove the paraffin oil. Treating the tape in hexane and heating the tape to about 70 ° C. to remove residual hexane, making the porous tape more porous than the precursor tape, compressing the porous tape, and then the tape Was stretched at 80-130 ° C to obtain a stretched product.

  The disadvantages of the known dental floss tapes are, in particular, for example when the interdental distance is small or when inserted between teeth that are in substantial contact with each other at some point, or during cleaning with dental floss, for example dentition When contacting the sharp end of an orthodontic appliance or bridge denture, premature tearing and breakage of the tape may occur and its mechanical properties are not sufficient for all situations.

  It is therefore an object of the present invention to provide a dental floss product comprising a single tape made of ultra-high molar mass polyethylene that does not exhibit the above-mentioned drawbacks, or at least has a low degree of drawbacks.

  This object is achieved according to the invention by means of a dental floss product in which the tensile strength of the tape is at least 1.8 GPa.

  The dental floss product according to the invention has very high mechanical strength, in particular tensile strength, high resistance to tearing and a low coefficient of friction. The tape can be inserted between the teeth in a tightly integrated state without breaking. A further advantage of the dental tape according to the invention is that during cleaning with dental floss, the dental tape maintains most of its initial strength even if the tape breaks into filaments. Yet another advantage is that little tape pilling occurs during fibrillation. This means that as a result of the local thickening, there is little risk that the tape will become stuck between the teeth. Furthermore, since the dental tape has a high elastic modulus and shows little elongation during use, it is possible to perform a cleaning operation with an accurate and controlled dental floss.

  The dental floss product according to the present invention comprises a single tape of ultra-high molar mass polyethylene, which tape is ultra-high molar mass polyethylene multifilament precursor for a time sufficient to at least partially fuse adjacent filaments. It is obtained by a method in which the body is exposed to a temperature within the melting point range of polyethylene while simultaneously stretching the precursor (described in detail below).

  The dental floss product includes a single tape of ultra high molar mass polyethylene (UHPE). Single tape in this context means that the supplied floss contains one single layer tape as opposed to a floss containing multifilament yarn.

  UHPE single tape means that UHPE is the primary polymeric material from which the tape is made, which provides mechanical properties. Preferably, the tape consists of at least 75% (m / m), more preferably at least 80%, or at least 85% UHPE. The tape may further comprise up to 25% (m / m) of an oil or wax or combination thereof that is compatible or miscible with UHPE above the melting temperature, ie above 150 ° C. or above 160 ° C. Examples of suitable oils and waxes include mineral oil (eg, heat transfer grade mineral oil having an average molar mass of about 250-700), vegetable oil (eg, coconut oil), or paraffin oil or paraffin wax, Preferably, a non-volatile solvent for polyolefin is used. In preferred embodiments, the tape comprises about 1-20%, or 2-16%, or 2.5-12% (m / m) of the oil or wax.

The intrinsic viscosity (IV) of ultra high molar mass polyethylene is greater than 5 dl / g. IV was prepared according to the method of PTC-179 (Hercules Inc. Rev., April 29, 1982) in decalin at 135 ° C. with a dissolution time of 16 hours and DBPC in an amount of 2 g / l with antioxidant. Used in solution and determined, and viscosities at different concentrations are estimated by extrapolating the concentration to zero. Intrinsic viscosity is a measure by which molar mass (also referred to as molecular weight) can be determined more easily than actual molar mass parameters such as _Mn and _Mw . There are several empirical relationships between IV and _Mw . For example, M _w = 5.37 × 10 ⁴ [IV] ^1.37 (see EP 0504951A1), but such a relationship depends on the molar mass distribution. The UHPE tape preferably has an IV of about 6-40 dl / g, more preferably 7-35 dl / g, or even 8-30 dl / g. Preferably, UHPE is a linear polyethylene of less than 1 branch per 100 carbon atoms and preferably less than 1 branch per 300 carbon atoms, the branched or side chain containing at least 10 carbon atoms. . The linear polyethylene may further comprise up to 5 mol% of one or more comonomers, for example alkenes such as propylene, butene, pentene, 4-methylpentene or octene.

  UHPE can be a single polymer grade, but can also be a mixture of two or more different polyethylene grades, for example with different IV or molar mass distributions and / or different types and numbers of comonomers or side chains. . The froth product UHPE tape according to the invention further comprises small amounts of conventional additives such as antioxidants, heat stabilizers, generally less than 5% (m / m), preferably less than 3% (m / m). , Colorants, flow promoters, and the like.

  The dental floss product according to the present invention comprises a single tape of ultra-high molar mass polyethylene, about 0.02-0.1 mm thick and about 0.25-6 mm wide. Tape thickness is related to the average distance between teeth that will vary considerably from person to person. The thickness is preferably about 0.03 to 0.09 mm or 0.04 to 0.08 mm to provide a balance between easy insertion, simple handling and strength. The width of the tape may also vary considerably, but is preferably about 0.3-5 mm, 0.4-4 mm, or 0 to balance between simple operation and effective plaque removal. .5 to 3mm. The ratio of dental tape width to thickness, or aspect ratio, is not critical and will vary greatly. Expressed in textile units, the tape generally has a linear density or titre of about 50 to 5000 dtex, preferably about 100 to 3000 dtex, or 150 to 2500 dtex. Tapes with low titers are generally more flexible and easier to use.

  The dental floss product according to the invention comprises a single tape of ultra high molar mass polyethylene with a tensile strength of at least 1.8 GPa. Such strength tapes do not easily break even when the user applies considerable force, but the high strength has the advantage of preventing tearing while passing between close teeth I know that there is. Therefore, preferably the tape has a tensile strength (also referred to simply as strength) of at least 2.0, 2.2, 2.4 or 2.6 GPa. The maximum strength of the tape is limited for practical reasons such as the availability of suitable yarns as precursors (see below) and is about 5 GPa. Tensile strength (simply strength) or toughness is determined from known methods based on ASTM D885-85 or D2256-97.

  In one embodiment of the dental floss product according to the present invention, the UHPE tape is free of fibrillation during use. Some users find such dental tape more convenient and more efficient for cleaning with dental floss. Tape without fibrillation can be obtained, for example, by a method in which the precursor multifilament UHPE yarn is thermally melted while carefully controlling the temperature and exposure time to promote melting and optionally applying pressure during melting. It was.

  In another embodiment of a dental floss product according to the present invention, UHPE tape exhibits fibrillation during use, where the tape divides into one or more filament tufts. The advantage of such a fibrillated tape is that during cleaning with dental floss, the tape spreads into filaments or tufts of filaments, thereby producing a more effective tooth surface cleaning operation. The advantage of the tape according to the invention is that the formed filaments are quite flexible and soft and show little risk of damaging the gums. Such fibrillated tape can be initially fibrillated, for example, by thermally melting the precursor multifilament UHPE yarn while carefully controlling the degree of fusion by adjusting conditions such as temperature and exposure time. It could be obtained by a method that produced a single tape.

  Although it is true that the first fibrillatable tape for use as a dental floss is described in US Pat. No. 4,646,766, this reference is based on a method of hot-melting multifilament yarns. Of course, it does not disclose or suggest making a high strength tape made of UHPE.

  In a preferred embodiment, the UHPE tape can be fibrillated during use, but maintains at least 75% of its initial strength after fibrillation. The tape according to the present invention does not break even if it is fine, but similarly fibrillates into filaments or tresses of high strength. Preferably, the fibrillated or at least partially fibrillated tape still has a strength of at least 80%, or as much as 90% of its initial strength. The advantage of such a tape is that there are no or very few broken filaments. Normally broken filaments tend to curl and form locally thick parts. This is often called pilling. Dental floss with pilling may become stuck between teeth, and if the user exerts a high force on this, there is a high risk of damaging gums or even teeth.

  In a preferred embodiment, the dental floss product according to the present invention comprises a single tape of ultra-high molar mass polyethylene, the tape having a surface that is not completely smooth but has a certain surface structure or surface roughness. Such a textured tape can be obtained, for example, by producing a UHPE tape by a process that includes optionally twisting and heat-melting multifilament yarn, so that the original filament structure is still partially Or some filaments were not fused at the surface of the tape. Such tapes have protrusions and / or grooves on their surface (hereinafter both simply referred to as grooves), which are generally primarily oriented in the length direction, and preferably the size is in the dimensions of the tape itself. Depending on the range, it is in the range of 0.002 to 0.05 mm. The advantage of such dental tape is that it slides easily between and above the teeth, but its small surface grooves allow the plaque to be crushed and removed, allowing it to be cleaned more effectively.

  Preferably, the groove size, ie width and depth or height, for more effectively crushing plaque is at least about 0.003 mm, 0.004 mm, or even up to 0.005 mm. The groove dimensions, in particular the depth, to provide a tape of good strength are preferably at most about 0.04 mm, or at most 0.03 mm. In the case of tapes made by heat melting a plurality of filaments, the dimensions of the grooves are generally similar to or less than the dimensions of the filaments.

  The grooves on the tape surface are mainly oriented along the length of the tape, but may be at an angle to the length direction. Preferably from about 0 to 45 °, more preferably from about 0 to 30 °, or angles from 0 to 20 °. It has been found that such a grooved tape more effectively removes loose particles / plaque from between the teeth.

  The dental floss product according to the present invention may further comprise conventional waxes and other additives. The tape can also be colored, for example, with a colorant that is preferably not saliva soluble but soluble in nonpolar drugs such as mineral oil or paraffin wax. The dental floss product may also include various coating agents such as waxes (other than the oils or waxes described above), or other, preferably saliva-soluble additives. Common additives include fluoride-containing compounds, flavorings, fragrances, small abrasive particles, or medicinal materials that attack, for example, bacteria in plaque.

  The invention further relates to a method for producing a single tape suitable for use in dental floss products from UHPE precursor materials.

  A method for producing such a single tape is known from EP 0662388 B1. In this patent specification, UHPE precursor tape is swollen with paraffin oil to a pseudo gel state, the pseudo gel is cooled to ambient temperature under controlled conditions, and the swollen tape is lightly squeezed to remove paraffin oil, Treat the tape in hexane and heat the tape to about 70 ° C. to remove residual hexane to make the porous tape more porous than the precursor tape, compress the porous tape, and then A dental floss comprising a single tape manufactured by a method comprising stretching at 80-130 ° C. to obtain a stretched product is described.

  The disadvantage of this known method is that it produces a tape that is prone to tearing when inserted between closely spaced teeth.

  The object of the present invention is to produce a single tape having a thickness of about 0.02 to 0.1 mm and a width of about 0.25 to 6 mm made from an ultra-high molar mass polyethylene precursor that does not exhibit the above disadvantages. It is to provide a way to make it possible.

  The purpose is that the precursor is a multifilament strand, and the precursor is exposed to a temperature within the melting range of the polyethylene for a time sufficient to at least partially fuse adjacent filaments while simultaneously stretching the precursor. This is achieved by the present invention by a method comprising:

  Using the method according to the invention, it is possible to produce tapes of specific dimensions that exhibit high tensile strength. A further advantage is that the fibrillation tendency and surface roughness of the tape can be controlled by fusing conditions such as exposure time and temperature.

  A method in which UHPE filaments are at least partly fused at high temperatures is known from EP 0 740 0002 B1, in which a monofilament fishing line is produced rather than the production of a tape of the dimensions of the invention. It has been explained.

  A multifilament strand is understood to be an article of indefinite length comprising a plurality of filaments made from UHPE. The precursor can be variously configured. For example, braided or twisted cords or ropes, or plyed yarns, folded yarns or twisted yarns, or air-entangled yarns. The use of arbitrarily twisted, multifilament yarns is advantageous because precursors and tapes can be made easily and cost-effectively. Preferably, at least 80% (m / m), more preferably at least 90% (m / m) of the multifilament strands are UHPE filaments, and most preferably the strands consist essentially of UHPE filaments, Yields a tape with high and low wear resistance.

  Spinning UHPE filaments and multifilament yarns into gel fibers with a solution of UHPE in a suitable solvent and drawing the fibers before, during and / or after removal of partial or complete solvent, i.e. so-called It can be prepared by gel spinning. Gel spinning of UHPE solutions is well known to those skilled in the art and is described in EP 0205960A, EP 0213208A1, US Pat. No. 4,413,110, GB 2042414A, EP 0200247B1, EP 0472114B1, WO 01 / 73173A1, and Advanced Fiber Spinning Technology, Editor, T.A. Nakajima, Woodhead Publ. It has been described in many references, including Ltd (1994), ISBN 1-855-73182-7, and references cited therein.

  The method according to the invention comprises the step of exposing the precursor to a temperature within the melting point range of UHPE for a time sufficient to at least partially fuse adjacent filaments. The conditions for this fusing step are selected such that the temperature and time of exposure are sufficient to soften the surface layer of the filaments in particular and to fuse them at least partially to form a single tape. The melting point range of UHPE is the temperature range between the peak melting point of the unoriented polymer and the constrained highly oriented UHPE fiber as determined by DSC analysis using a scan rate of 20 ° C./min. For UHPE filaments, it generally exhibits a melting point range of 138-162 ° C, and the exposure temperature is preferably within the range of about 150 ° C to about 157 ° C. The residence time during which the precursor is exposed to the melting temperature may vary within a wide range, but is generally in the range of about 5 seconds to about 1500 seconds. Although high temperatures tend to accelerate the fusion process, care should be taken not to overheat or time too long. This is because the strength of the product may be lost due to, for example, partial melting or other molecular relaxation effects within the filament core. Suitable means for performing this process include ovens with precise temperature control and stretching means. These are known to those skilled in the art and are alternative means for carrying out the method according to the invention.

  During the fusion process, the appearance of the precursor is generally from an initial, eg, white, opaque appearance to a translucent, milky or substantially transparent appearance, depending on the degree of fusion, the type of precursor material, and optional additives. Even the tape may change. Increasing the degree of fusion between filaments generally increases the light transmission of the product.

  A high degree of fusion that results in a translucent tape in which virtually all filaments are fused to form a smooth surface product is preferred for producing dental tape products that exhibit little or no tendency to fibrillate during use. The degree of fusion can be adjusted by changing the exposure temperature and time in the method according to the invention. The degree of fusion can be determined by applying a force to one or both sides of the tape during the process, for example by guiding it between a pair of rollers or by pulling on a member or bar such as a free rotating roller or drive roller Additional acceleration can be achieved by compressing the precursor. Especially when producing non-fibrillated tapes, this member is also preferably temperature controlled, more preferably set to a temperature setting that is one or two degrees higher than the oven air. This results in a smoother surface and improves the wear resistance of the monofilament-like product. The pressure applied to the precursor (or tape), by changing the tension of the yarn and / or by changing the length of the contact surface between the yarn and the member of the precursor (eg a cylindrical roller or bar) Can be adjusted (by adjusting the diameter). One skilled in the art can find the desired combination by several experiments.

  In order to produce a smooth tape, the surface of the aforementioned member is also flat and smooth. If a specific surface texture is desired for the tape, the member preferably comprises a surface texture.

  The degree of fusion can be determined on the resulting product, for example by visual evaluation of the surface and / or cross-section, for example with the naked eye or using an optical or electron microscope. Another possibility for determining the amount and rate of absorption of colored liquid, for example from a marker, is described in EP 0 740 0002 B1. The degree of fusion can also be derived from a simple test that determines the number of operations before the product is repeatedly worn, eg on the surface of a metal bar, and a single tape product is broken down into its constituent filaments. .

  The method according to the invention involves simultaneously stretching the precursor. Stretching is a result of a thermal molecular relaxation process that applies a draw ratio, also called stretch ratio, greater than 1.0 to the precursor, thus keeping the filament under tension. , Which means to prevent the filament strength from decreasing. Preferably, a draw ratio of at least 1.5, 2.0 or even at least 2.5 is applied to further improve the particularly tensile strength properties of the resulting tape. Above a certain draw ratio, this effect may level off or even diminish as a result of partial damage or breakage of the filament. Furthermore, the higher the stretch ratio, the lower the product titer. The maximum draw ratio therefore depends on the type of precursor and its filament and is generally at most about 10 or at most 8 or 6.

  The dimensions of the tape obtained are the titer of the precursor strand, the number and thickness of the filaments (filament titer, generally expressed in denier per filament or dpf), the level of twist or entanglement of the yarn, the filament before fusing It can be controlled by factors such as the degree of spread and the degree of elongation during fusion.

  In a preferred embodiment, the method according to the invention further comprises spreading the precursor filaments prior to fusion. The degree of filament spreading is one way of adjusting the thickness and width of the tape. For example, the spreading of the multifilament yarn can be carried out by known methods, for example by guiding the yarn on a so-called spreading bar. The minimum tape thickness mainly corresponds to at least two layers of filaments in contact with each other, otherwise melting is not effective. Preferably, after spreading, the precursor comprises at least three layers of filaments for better fusion and control of the degree of fusion. For the same reason, the precursor is preferably at least one multifilament yarn that is slightly twisted, in particular a twist factor of 0-0.5, more preferably 0.01-0.4. ) (Also referred to as the twist multiplier). Such a level of twist allows control of the number of filament layers after spreading, and facilitates fusion because the filaments are in good contact, thus making it possible to produce a single thin tape. Such twist levels also result in filaments that are oriented at least partially at an angle with the length of the tape. High twist levels generally result in thick tapes and large orientation angles.

  The extent of spread and hence the width of the tape can be further limited and adjusted by providing grooves or ridges in the widening bar and / or the following guide rollers and bars in the process. Defines the maximum tape width that the distance between ridges or groove widths can be achieved. The surface between the ridges or the interior of the groove and all other guide members affect the form of the tape and are preferably flat.

  The precursors used in the method according to the invention can comprise UHPE filaments with widely varying filament diameters or titers. In general, thick filaments are subjected to processes involving relatively high draw ratios, eg greater than 2 or 2.5. Suitable filament thicknesses range from 0.2 to 15 dpf, preferably the precursor comprises filaments with a thickness of about 0.3 to 12, or 0.5 to 10 dpf, resulting in a high strength tape.

  During the process according to the invention, the filaments are drawn and fused and a tape of constant strength is produced. Preferably the strength of the tape is at least 1.8 GPa. Preferably, the initial strength of the precursor is at least 1.0 GPa, more preferably at least 1.5, 1.8, or even up to 2.0 GPa. The higher the strength of the precursor, the less stretch is required during the fusion process to produce a high strength tape.

  The method according to the present invention further comprises cooling the tape after filament fusion and stretching. Preferably, the tape obtained by the method according to the invention is cooled while the tape remains under tension. This is advantageous because the orientation of the product obtained by fusion and stretching is better maintained at both the filament and molecular levels. Such tension can result, for example, from winding the tape product into a package after the previous step of the process and cooling the package.

  The method according to the invention can further comprise a preceding step of pretreating the precursor or one or more yarns therein in order to increase the bond between the filaments during the fusing step. Such pretreatment steps may include coating the precursor with a component or composition, washing off the precursor, i.e. washing away surface components such as spin finishes, or high voltage plasma or corona treatment. Or, any combination thereof may be included. Preferably, the precursor comprises filaments that are substantially free of spin finish. This means that the product has not been subjected to any spin finish, or any spin finish present is substantially removed in the pretreatment step. This is advantageous because the fusing effect is improved and the wear resistance of the tape product is further improved.

  In other preferred embodiments, an effective amount of oil or wax, such as, for example, a non-volatile, solvent for polyolefins, such as mineral oil, vegetable oil, or paraffin oil or wax, is applied, for example by dipping or wetting. By pretreating the precursor. This pretreatment step may be performed at ambient conditions, or at elevated temperatures up to below the melting temperature range of the polyolefin fibers, and may be simultaneous with stretching and melting. The advantage of this embodiment is that the efficiency of the fusion process is further increased. That is, a high degree of fusion can be obtained under the same conditions, or a similar degree of fusion can be obtained at slightly lower temperatures, shorter times or less pressure.

  In particular embodiments, the oil or solvent may further comprise other additives such as colorants, fragrances or flavorings. Such additives should of course be sufficiently stable to withstand the subsequent fusion and stretching process. The advantage of this embodiment is that a colored or scented tape can be obtained in a one-step process. These additives can be oil-soluble or saliva-soluble depending on whether leaching of the additive into the oral cavity is desired during dental floss cleaning.

  The method according to the present invention further comprises the step of applying the coating composition to the tape after fusing and stretching to form a coating layer. Such coating compositions may contain other waxes and other conventional additives for dental floss, preferably saliva soluble additives.

  The dental floss product can be any known product that includes dental tape and is suitable for cleaning with dental floss. Typical examples include two hand-held containers or dispenser containers containing a single tape from which a desired length can be dispensed or two pieces of tape provided from between Includes handheld devices with

  The present invention further relates to a method for treating said area in the oral cavity comprising the cleaning of adjacent areas and subgingival areas with dental floss with a dental floss product according to the present invention.

  The invention will now be further illustrated by the following experiments.

Example 1
As precursor (feed) material, non-twisted gel spun UHPE yarn was applied. The yarn was composed of 100 filaments, the yarn titer was 243 dtex, the tensile strength was 35.1 cN / dtex, the tensile modulus was 1242 cN / dtex, and the elongation at break was 3.3%.

Excess oil was wiped off by passing the precursor through a liquid paraffin bath as a pretreatment step and between nonwovens. The paraffin content was calculated to be about 11% by weight by determining the mass increase due to this step. The precursor was guided at a constant speed of 4.0 m / min onto a first set of drive rollers and then onto a widening rod in an oven maintained at a constant temperature of 153.6 ° C. Inside the oven, the precursor was guided on several cylindrical bars with a smooth surface and reached a length of 8.4 m in the oven. At the exit of the oven, the yarn was guided onto a second set of drive rollers. The speed of the second roller was 7.2 m / min, resulting in a draw ratio of 1.8, and the draw speed in the oven was about 0.4 min- ¹ .

  The resulting tape was somewhat translucent and showed bonding during friction between fingers.

  Nominal gauge length using a Zwick 1435 tester as specified in ASTM D885M for the tensile strength (or strength), tensile modulus (and modulus) and elongation at break (eab) of multifilament yarns and tapes. Define and determine using 500 mm fiber, 50% / min crosshead speed and Instron 2714 clamp. For strength calculation, the determined tensile force is divided by the titer determined by weighing the 10 meter (or other length) fiber. Elongation is the measured elongation at break and is expressed as a percentage of the original length of the specimen after clamping.

  The resulting tape has a titer of 146 dtex, a tensile strength of 36.7 cN / dtex, an elastic modulus of 1447 cN / dtex, and an elongation at break of 3.2%.

  The width of the tape is about 0.5 mm and the thickness is about 30 microns. Under the optical microscope, a small groove was visible mainly in the length direction and in particular on one of the surfaces.

  The tape was further examined by electron microscopy. First, paraffin oil was extracted from the tape with n-hexane for several minutes. After drying, the tape was embedded in an epoxy resin. A cross section of the tape was prepared using a cryo-microtome using a diamond blade. After cutting, the block surface sample was fixed to a sample holder and covered with a conductive carbon layer. For imaging, a Philips CP SEM XL30 was used with a Robinson backscatter detector at an acceleration voltage of 15 kV. In FIG. 1, a dark area is a filament, and a bright part shows a part of cross section of embedding resin. On one side it can be seen that all the filaments appear to be fused and the surface looks quite smooth. On the other side, there are clearly some openings between the filaments, which appear primarily as longitudinal grooves on the surface. The area filled with resin indicates that the filaments have been partially fused.

  The tendency of the tape to fibrillate, reciprocating about 25 cm long tape over a 3 mm diameter metal rod at a frequency of about 1 Hz and a tension equal to about 4% of the tensile strength of the tape, ambient temperature and dry conditions. Determined by letting. After 15 cycles, some filaments separated from the tape. Only a few were damaged. After 35 cycles, the number of filaments increased but was still tape. The experiment was terminated after 100 cycles when the tape was completely fibrillated.

Example 2
A tape was produced from the indicated precursor yarn in the same manner as in Example 1, but this time the yarn was twisted with a twist factor of 0.2. Although the tensile properties were virtually the same, the tape exhibited a high degree of fusion and the first filament appeared only after 30 cycles, as evidenced by a low tendency to fibrillation, and 100 cycles. Later, the tape was not completely fibrillated.

The dark area is the filament, and the bright area shows part of the cross section of the embedded resin.

Claims (13)

A dental floss product comprising a single tape of ultra-high molar mass polyethylene having an intrinsic viscosity of at least 5 dl / g as measured in decalin at 135 ° C., wherein the thickness of the tape is about 0.02 to In a dental floss product that is 0.1 mm and a width of about 0.25 to 6 mm,
A dental floss product, wherein the tape has a tensile strength of at least 1.8 GPa.   The dental floss product according to claim 1, wherein the polyethylene is linear and has an intrinsic viscosity of 7 to 35 dl / g.   The dental floss product of claim 1 or 2, wherein the tape has a tensile strength of at least 2.0 GPa.   The dental floss product according to any one of claims 1 to 3, wherein the tape is not fibrillated during use.   The dental floss product according to any one of claims 1 to 3, wherein the tape exhibits fibrillation during use.   6. The dental floss product of claim 5, wherein the tape maintains at least 75% of its initial strength after fibrillation.   The dental floss product of any one of claims 1 to 6, wherein the tape exhibits grooves on its surface. A process for producing a single tape of about 0.02-0.1 mm thick and about 0.25-6 mm wide from an ultra-high molar mass polyethylene precursor comprising:
The precursor is a multifilament strand, and the method exposes the precursor to a temperature within the melting point range of polyethylene for a time sufficient to at least partially fuse adjacent filaments, while simultaneously the precursor. A method comprising stretching.   The method of claim 8, wherein the temperature is in the range of about 150 ° C. to about 157 ° C. or less.   The method according to claim 8 or 9, wherein the precursor comprises at least one twisted multifilament yarn having a twist coefficient of 0.01 to 0.4.   10. A method according to claim 8 or 9, wherein the precursor comprises a filament that is substantially free of spin finish.   10. The method of claim 8 or 9, further comprising pretreating the precursor by depositing oil or wax.   13. A method according to claim 12, wherein the oil or wax comprises an additive.

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