DE102011052657B4 - Cadenced bowstring for a viola bow - Google Patents

Abstract

Bow covering for a viola bow, comprising a polymer composition consisting of polyamide-6 and at least one additive in the form of an extruded yarn, the yarn having a regular cycle with regard to the maximum and minimum yarn radii (A1, A2), the cycle length in the longitudinal direction (d) from 5 to 25 mm.

Description

The invention relates to a bowing for a viola bow according to claim 1.

The invention also relates to the use for making a viola bow and a viola bow. To make bows from stringed instruments (i.e., bowed strings), horsehair (usually from molds) are standardly used as stringing. However, these have the disadvantage that they wear over time by abrasion on the sides of the instrument and also not resistant to moisture, especially against high humidity, and to temperature fluctuations.

The patent DD 36 347 A describes a plastic bow hair for stringed musical instruments, wherein a single hair has a non-round cross-section and a permanent twist. The bow hair disclosed in this document consists of polyamide-6.10, polyamide-8 or polyamide-11.

However, the sheet coverings described in this document are not yet optimal in terms of wear resistance, sensitivity to humidity and temperature fluctuations and the sound volume produced when brushing stringed instruments.

Presentation of the invention, object, solving advantages

It is the object of the invention to provide a material for the covering of viola bows, which does not have the above-mentioned disadvantages of the prior art.

A solution of the object of the invention is surprisingly achieved by the bowstring according to claim 1.

This is very resistant to moisture of all kinds (especially humidity), as well as temperature fluctuations and is not rubbed off even when used over several years as a covering of string instrument bows. It is also inexpensive and easy to manufacture.

Also preferred is a polymer composition wherein the modulus of elasticity of the polymer composition is from 5,000 to 5,800 MPa. Particularly preferred is a polymer composition, wherein the yarn has a diameter in the range of 0.5 to 1.5 mm, in particular 1.2 mm. Such a material is optimal in terms of the above-mentioned advantages for a bowing.

By polymer composition is meant any composition which contains at least one kind of polymer as an essential ingredient. This typically means that the physical and chemical properties of the composition are largely or even exclusively determined by the properties of the polymers contained. Polymer is understood to mean any chemical compound of chain or branched molecules (i.e., macromolecules) composed of the same or at least similar units (i.e., monomers). Examples of polymers are homopolymers, i. H. Monomeric type polymers such as polyethylene, polypropylene, polyvinyl chloride or polyamide-6, copolymers, d. H. Polymers of a plurality of mutually different monomers, such as polyesters, polyurethanes and polyamide-66, and polymer alloys, d. H. Mixtures of different polymers and copolymers.

Polyamide (abbreviation PA) is understood as meaning any polymer whose repeating units have a functional amide group as a characteristic feature. This amide functional group may be generally understood as a condensation product of an organic carboxylic acid with an organic amine to form an amide bond. Preferably, the amide bond is hydrolytically cleavable. The polyamide belongs to the group of thermoplastics. According to the invention, the polyamide or the polymer can be selected from the group consisting of aliphatic polyamides, partly aromatic polyamides and aromatic polyamides (polyaramides).

Aliphatic polyamides are understood as meaning those polyamides whose monomers can be derived from aliphatic basic bodies. Examples of aliphatic polyamides are polyamide-6 and polyamide-66.

By polyamide-6 is meant an aliphatic polyamide resulting from a condensation of ε-caprolactam. Alternative names for polyamide-6 are polycaprolactam or PA-6. Polyamide-6 has the advantage that it is available inexpensively in large quantities.

By polyamide-66 is meant an aliphatic polyamide resulting from a condensation of hexamethylenediamine and adipic acid. An alternative designation for polyamide-66 is PA-66.

Partially aromatic polyamides are polyamides whose monomers are at least partially derived from aromatic starting materials. Examples of partially aromatic polyamides are polyamides of hexamethylenediamine and terephthalic acid (alternative name PA-6T).

Aromatic polyamides (polyaramides) are polyamides whose monomers are derived from exclusively aromatic starting materials. Examples of aromatic polyamides are para-phenylenediamine and terephthalic acid, such as aramid.

The polymer compositions according to the invention are optimal in view of the physical parameters required for use as a sheet covering, in particular the modulus of elasticity, the yield stress, the elongation at break, the tensile strength, the breaking stress and the elongation at break, as is also apparent from the attached experimental examples.

E modulus (modulus of elasticity, tensile modulus, coefficient of elasticity, E) is understood to mean the material characteristic value from materials engineering, which describes the relationship between mechanical stress σ and strain ε in the deformation of a solid body with linear elastic behavior.

The modulus of elasticity is the proportionality constant in Hooke's Law (see Eq.1) and has the unit of a mechanical stress. E = = σ / ε = const. (Equation 1)

Typically, the modulus of elasticity is given in units of megapascals (MPa) or kN / mm ² . The amount of modulus of elasticity is greater, the more resistance a material is able to counteract a mechanical deformation. This means that a high modulus material has high rigidity and a low modulus material has high compliance.

The tensile strength σ _m is understood to mean the stress σ, which is calculated in the tensile test from the maximum tensile force achieved, based on the original cross-section of the sample. The tensile strength has the dimension force per surface and is typically given in megapascals (MPa) or kN / mm ² .

The elongation at break (elongation at break) A is understood to mean the material characteristic value which indicates the permanent elongation ΔL of a sample to be tested after fracture with respect to the initial measuring length L ₀ in the tensile test. It results from the following equation (see equation 2).

The permanent extension ΔL is the length after the break reduced by the initial measuring length L ₀ .

Breaking stress σ _B is understood to mean the force drop that occurs when the maximum force is exceeded at which the material just barely deforms elastically. The breaking stress is typically given in units of megapascals (MPa) or kN / mm ² .

The yield stress σ _γ in the stress-strain diagram is the first stress value at which an increase in strain occurs without increasing the stress. At this point, the first derivative of stress versus strain is zero (see equation 3): ∂σ / ∂ε = 0 (equation 3)

Usually, the yield stress is given in the unit Megapascal (MPa) or kN / mm ² . The yield stress may be less than the fracture stress of a sample.

Elongation at yield is understood to mean the elongation ε _γ at yield stress σ _γ .

It is of advantage if the polymer composition for use as a bowed covering complies with the modulus limits for the modulus of elasticity, the yield stress, the elongation at break, the tensile strength, the breaking stress and the elongation at break described in the application.

The polymer composition is also preferably a thermoplastic which can be extruded by melt extrusion in the form of a thread or yarn.

In addition, dyes of any, invariable and / or abrasion-resistant dyeings can be added to the polymer composition in the melt. For example, when a yellow dye is added to the polymer composition, a yarn may be obtained in the color of a horse bristle, which is also commonly used as a bowed garnish. In this way the impression of natural hair tension can be created. Preferably, dyes are used which have high stability to hue changes over time. Examples of such dyes are titanium dioxide, cadmium sulfide, cadmium selenide, carbon. Alternatively, finished yarns prepared from the polymer compositions may be dyed with disperse dyes. Such processes are already known in the production of textiles.

The present invention further relates to a use of the sheet covering according to the invention for producing a viola bow.

For this purpose, it is particularly preferred that the polymer composition is brought into a cadenced structure by melt extrusion or by other suitable means known to those skilled in the art. Preferably, the polymer composition is melt-extruded in the form of a yarn having regular longitudinal cycling the cycle length in the longitudinal direction d and the amplitude difference A2-A1 over the length of the extrusion are substantially the same (see 1 ). In this case, the extrudate can be produced by melt extrusion, in which case it can be used directly as a yarn, or in addition can have been drawn, resulting in a drawn yarn. For example, the cadenced structure can be achieved by stretching three times (150% of the full elasticity of the yarn is observed).

The invention also relates to a viola bow containing the bowing according to the invention. Compared to conventional bowing, such as conventional horsehair, the yarn of the invention is temperature resistant and insensitive to variations in humidity. In addition, the bowed fabric of the present invention provides better tone stability and tone volume when used in conjunction with the bowed instrument, and higher abrasion resistance over several years, for example, over more than 10 years of use by a professional stringed instrument player.

Further advantages and embodiments can be found in the following experiments, the figures and the dependent claims.

Examples

Hereinafter, the invention based on embodiments and with reference to the 1 explained in more detail.

The 1 Figure 11 is a sketch of the yarn made with the polymer composition for use as a briquetting sheet.

The embodiments and the figure are intended only for a general understanding of the invention and in particular are not to be interpreted as limiting the scope of the invention.

Example 1.

• – Polyamid-6 (PA-6 Ultramid^® B3, MFI = 20 (235°C), hergestellt durch die BASF AG);
• – Additiv 1 (Ethylen/Ethylacrylat/Maleinsäureanhydrid-Terpolymer mit einer Zusammensetzung von 69 Gew.-%/30 Gew.-%/1 Gew.-%, MFI = 6 (190°C));
• – Additiv 2 (Ethylen/2-Ethylhexylacrylat/Maleinsäureanhydrid-Terpolymer mit einer Zusammensetzung von 69 Gew.-%/30 Gew.-%/1 Gew.-%, MFI = 5,5 (190°C));
• – Additiv 3 (Ethylen/2-Ethylhexylacrylat/Maleinsäureanhydrid-Terpolymer mit einer Zusammensetzung von 67 Gew.-%/32 Gew.-%/1 Gew.-%, MFI = 6 (190°C));
• – Additiv 4 (Ethylen/2-Ethylhexylacrylat-Copolymer mit einer Zusammensetzung von 70 Gew.-%/30 Gew.-%, MFI = 2 (190°C));
• – Additiv 5 (Ethylen/Butylacrylat-Copolymer mit einer Zusammensetzung von 70 Gew.-%/30 Gew.-%, MFI = 2 (190°C)).

For compositions 1 to 7, the following starting materials are used:

• - polyamide-6 (PA-6 Ultramid ^® B3, MFI = 20 (235 ° C) manufactured by BASF AG);
• Additive 1 (ethylene / ethyl acrylate / maleic anhydride terpolymer having a composition of 69% by weight / 30% by weight / 1% by weight, MFI = 6 (190 ° C));
• Additive 2 (ethylene / 2-ethylhexyl acrylate / maleic anhydride terpolymer having a composition of 69% by weight / 30% by weight / 1% by weight, MFI = 5.5 (190 ° C));
• Additive 3 (ethylene / 2-ethylhexyl acrylate / maleic anhydride terpolymer having a composition of 67% by weight / 32% by weight / 1% by weight, MFI = 6 (190 ° C));
• Additive 4 (ethylene / 2-ethylhexyl acrylate copolymer having a composition of 70% by weight / 30% by weight, MFI = 2 (190 ° C));
• Additive 5 (ethylene / butyl acrylate copolymer having a composition of 70% by weight / 30% by weight, MFI = 2 (190 ° C)).

Preparation of the compositions 1 to 7 according to the invention is carried out by melting the individual components in the twin screw extruder or single-screw BUSS ^® -Cokneter by conventional methods.

The compositions 1 to 3 and 6 to 7 are first mixed in the single-screw BUSS ^® co-kneader, melted and then extruded in a post-treatment extruder. For this purpose, the starting materials, ie polyamide-6 and terpolymers, are introduced as granules in the mixer.

For compositions 4 and 5, a co-rotating 40 mm twin screw "Werner 40" extruder is used. Also for the preparation of these compositions, the starting materials are added as granules in the mixer.

The starting materials used can be taken from Table 1. Table 1: Starting materials of the polymer compositions used. Composition no. starting materials 1 2 3 4 5 6 7 PA 6 100 80 80 80 80 80 80 Additive 1 20 20 Additive 2 20 Additive 3 20 Additive 4 2 2 Additive 5 18 18

Example 2.

Tensile tests were carried out on compositions 1 to 7 (about 21 ° C., about 20% relative humidity).

The measuring instrument used was a tensile tester with mechanical long-distance transducers, T1-FR010TH.A50; Software TestXpert V11.02 manual, company Zwick GmbH & Co. KAG used. The average values of these parameters for the compositions 1 and 2 are shown in Table 2. Table 2: Results of tensile tests on the polymer composition. parameter Composition no. 1 2 Modulus of elasticity [MPa] 3264 6004 Tensile strength [MPa] 83 405 Breaking stress [MPa] 83 405 Elongation at break [%] 37 12 Yield stress [MPa] 81 57 Elongation at break [%] 3.5 1.5

Table 2 shows the mean value of the material properties from three measurements as well as the standard deviation from the measured values. In the yield stress and the elongation at break, the periodically occurring yield stress and yield strength are indicated (lowest measured values).

Compared to composition 1, composition 2 exhibits a higher modulus of elasticity, a higher tensile strength, a higher breaking stress, a lower elongation at break, a lower yield stress and a lower elongation at break. Compositions 3 to 7 each showed similar results as composition 2.

Example 3.

For moisture absorption, the polymer composition 2 was stored for 36 h under the conditions given in Table 3 and then dried at 120 ° C to constant mass. Table 3: Moisture uptake results on the polymer composition. Storage of the composition at Measured value [%] 23 ° C, 30% rel. humidity 3.2 +/- 0.2 23 ° C, in water 9.4 +/- 0.3

Table 3 shows the mean of two measurements and the standard deviation.

Example 4.

To determine the thermal properties, a differential scanning calorimetry (DSC) measurement is carried out on the polymer composition 2 (without prior drying).

• 1. 25 bis 200°C
• 2. 200 bis 25°C
• 3. 25 bis 350°C

Tabelle 4: Ergebnis der DSC Messung an der Polymerzusammensetzung. Messparameter Messwert Schmelztemperatur 216 bis 225°C Glasübergangstemperatur nicht detektiert Measuring device: Seiko Exstar 6000 DSC 6000, aluminum pans (d = 5 mm) Temperature program, heating rate 10 ° C / min

• 1. 25 to 200 ° C
• 2. 200 to 25 ° C
• 3. 25 to 350 ° C

Table 4: Result of DSC measurement on the polymer composition. measurement parameters reading melting temperature 216 to 225 ° C Glass transition temperature not detected

The second heating curve was evaluated in each case.

Example 5.

According to the method in Example 1 are further polymer compositions 8, 9 and 10 made, which in turn ^® initially in the single-screw BUSS -Cokneter mixed, melted and then extruded in an aftertreatment extruder. Table 5: Starting materials used in the polymer compositions. Composition no. starting material 1 2 8th 9 10 PA-6 100 80 95 90 85 Additive 1 20 5 10 15

The polymer compositions 1, 2, 8, 9 and 10 are melt-extruded in the form of a yarn by conventional methods. The yarns prepared from the compositions have a diameter of 0.12 mm.

The yarns thus produced all have a regular clocking in the longitudinal direction which can be detected under the light microscope, the cycle length in the longitudinal direction d and the amplitude difference A2-A1 remaining substantially unchanged over the length of the extrusion. In analogy to Example 2, the E-moduli of the polymer compositions 1, 2, 8, 9 and 10 are also determined. The cycle lengths in the longitudinal direction d and the E-modules are given in Table 6. Table 6: E-Modules of Polymer Compositions. Composition no. 1 2 8th 9 10 Modulus of elasticity [MPa] 3264 6004 3971 4686 5591 Cycle length in the longitudinal direction d [mm] irregular 1.2 63 43 6

The yarns of polymer compositions 1, 2, 8, 9 and 10 are clamped between the head and the adjustable turnbuckle of a bow customary for use with stringed musical instruments and used by professional stringed instrument players to coat various stringed instruments. The sound stability when brushing over a period of 3 hours is estimated by the professional string instrument players (5 each per musical instrument).

The result is the result of the estimation shown in Table 7. Table 7: Assessment of sound stability. instrument empty strings Frequency of the fundamental tones [Hz] Composition no. 1 2 8th 9 10 violin g - d ¹ - a ¹ - e ² 196 to 659 - ++ - + + viola c - g - d '- a' 130 to 440 - + + + ++ violoncello C - G - d - a 65 to 220 - + + ++ + double bass Contra-C -, E - .A - D - G 41 to 98 - - ++ + -

In Table 7, a "-" predicts that the sound stability is considered "rather poor", "+" means that the sound stability is considered "rather good" and "++" means that the sound stability is "very good "Was estimated.

The sound volume was rated "good" to "very good" when using all bows in conjunction with all musical instruments.

All sheet coverings from the polymer compositions 2, 8, 9 and 10 showed no visible surface wear even after a period of 3 to 6 hours under the microscope. The sound stability also did not change when the room temperature varied and the humidity changed.

Claims (6)

A bowing fabric for a viola bow, comprising a polymer composition consisting of polyamide-6 and at least one additive in the form of an extruded yarn, the yarn having a regular timing with respect to the maximum and minimum yarn radii (A1, A2), the cycle length being in the longitudinal direction (d) from 5 to 25 mm. The signature of claim 1, wherein the modulus of elasticity of the polymer composition is from 5,000 to 5,800 MPa. Sheet covering according to claim 1 or 2, wherein the yarn has a diameter in the range of 0.5 to 1.5 mm, in particular 1.2 mm. Use of the bowing according to one of claims 1 to 3 for the production of a viola bow. Viola bow containing the bowstring according to one of claims 1 to 3. A viola bow according to claim 5, suitable for playing a viola, the empty strings of the viola vibrating at a fundamental tone in the range 130 to 440 Hz.

Images