Artificial hair and method for producing same

Abstract

The present invention relates to artificial hair comprising cellulose fibers, wherein the cellulose from which the cellulose fibers are formed has a degree of polymerization of 100 to 450.

Description

[0001] Synthetic hair and process for producing the same

[0002] Description

[0003] The present invention relates to artificial hair, i.e., synthetic hair that is characterized by skin-friendly and excellent mechanical properties and can be produced using a sustainable, environmentally friendly process. The synthetic hair according to the invention is suitable for both hairpieces and hair extensions. Furthermore, the present invention also relates to uses of specific cellulose fibers.

[0004] In the past, human hair was primarily used to make hair replacement products. While human hair is high-quality, it is expensive and is increasingly discredited for ethical reasons. Since plastic can be spun into fibers on an industrial scale, the production of synthetic hair, for example, acrylic-based, has become increasingly popular, as exemplified in EP 3069625 A1. However, acrylic-based synthetic hair, as disclosed in the aforementioned publication, has disadvantages. In particular, it involves fiber filaments made of plastic that are not biodegradable, which is unacceptable in light of sustainability and environmental friendliness. Furthermore, the product properties of plastic-based synthetic hair are often difficult to compare with real hair, which can manifest itself, for example, in differing elasticity and fineness, but also in an unnatural shine or artificial feel.To improve the properties of synthetic hair and make it more similar to real hair, it is typically treated with various chemicals, which can lead to skin irritation. Synthetic hair based on synthetic materials can also release monomers during production or during use under UV light or high temperatures, which can be damaging to the skin or even harmful to health.

[0005] Based on the above prior art, it is an object of the present invention to provide synthetic hair characterized by very good real-hair-like properties and, moreover, by high skin-friendliness. The synthetic hair should also be capable of being produced sustainably and in an environmentally friendly manner. Thus, it is also an object of the present invention to provide a method by which skin-friendly synthetic hair can be produced sustainably and in an environmentally friendly manner. Furthermore, it is an object of the present invention to provide uses for specifically designed cellulose.

[0006] The objects are achieved by the subject matter of the independent claims. The dependent claims contain advantageous developments and refinements of the invention.

[0007] According to the invention, the problem is solved by a synthetic hair based on cellulose fibers.

[0008] Synthetic hair within the meaning of the present invention is one or more cellulose-based monofilaments that can be worn, for example, as a wig or partial hair replacement, or woven into one's own hair as a ponytail or strand (also known as "braids"). The cellulose from which the cellulose fibers constituting the synthetic hair according to the invention are formed has a degree of polymerization of 100 to 450. It should be noted that cellulose is composed of glucose units. It is essentially a polymer of monomeric glucose units. The degree of polymerization of the cellulose refers to the number of glucose units, which according to the invention ranges from 100 to 450. The cellulose used according to the invention is spun into fibers, as explained later. The degree of polymerization may change during the process.However, the degree of polymerization of the cellulose fibers in the finished synthetic hair remains in the range of 100 to 450. However, since the degree of polymerization can be determined more easily in the cellulose to be used for the synthetic hair, the degree of polymerization is, according to the invention, referenced to the cellulose from which the cellulose fibers contained in the synthetic hair according to the invention are formed.

[0009] According to the invention, it was found that if the degree of polymerization is below 100, sufficient strength, tensile strength, and knot tensile strength cannot be achieved. If the degree of polymerization is above 450, the stretchability and elasticity are insufficient. The aforementioned properties influence the combability, moldability, and drapability of the synthetic hair, which must be present to make the synthetic hair appear and be used like real hair.

[0010] The synthetic hair according to the invention is characterized by its high sustainability, biodegradability, and thus high environmental friendliness due to the use of cellulose. It is essentially a natural product that is very skin-friendly and possesses all the mechanical properties required for synthetic hair, as well as a soft feel, making it very comparable to real hair and blending in seamlessly with it. Furthermore, as stated above, the synthetic hair can be processed like real hair and, in particular, is drapeable—i.e., it is not only combable but also moldable, which is essential for styling hairstyles.

[0011] In order to further improve the processability of the synthetic hair, in particular its combability, formability and drapability, the cellulose from which the cellulose fibers are formed advantageously has a degree of polymerization of 200 to 400.

[0012] According to a further advantageous development, the cellulose from which the cellulose fibers are formed comprises microcrystalline cellulose. In particular, the cellulose from which the cellulose fibers are formed is microcrystalline cellulose, i.e. it preferably consists of microcrystalline cellulose. According to the invention, microcrystalline cellulose is understood to mean purified, partially split or depolymerized cellulose which is obtained from plant fibers. The plant material from which the plant fibers are obtained is often cotton linters or wood pulp, which is broken down into small components with the aid of mineral acids, enzymatic hydrolysis or mechanical processes to obtain cellulose. Alternatively, other cellulosic raw materials can be used to produce microcrystalline cellulose. By splitting orDepolymerization refines the pulp and converts it into microcrystalline cellulose, which has a lower degree of polymerization than the original pulp. Through this splitting or depolymerization, the degree of polymerization of the cellulose can be precisely adjusted. The use of microcrystalline cellulose thus offers the possibility of precisely adjusting the fiber properties essential for synthetic hair, such as fineness, extensibility, strength, tensile strength, elasticity, and knot tensile strength. Furthermore, the processability of the synthetic hair, especially its combability, moldability, and drapability, can be precisely adjusted.

[0013] To achieve a balanced ratio of fineness, tensile strength, extensibility, tear resistance, modulus of elasticity, and knot tensile strength, it has proven particularly advantageous if the synthetic hair also contains at least one plasticizer. The aforementioned properties can thus be particularly well adjusted. The fineness-related tensile strength can be adjusted within a range of 8 to 16 cN / tex and the elongation within a range of 11 to 24%. In addition, by adding at least one plasticizer, the modulus of elasticity can be adjusted within a range of 280 to 550 cN / tex and the knot tensile ratio within a range of 40 to 85%. Fiber fineness is determined according to DIN EN ISO 1973, the fineness-related tensile strength and elongation according to DIN EN ISO 5079, and the knot tensile ratio according to DIN 53842-1. The modulus of elasticity is determined according to DIN EN ISO 5079 and read off at 0.5 to 0.7%.The above values ​​are obtained under the processing and spinning conditions as specified in the experimental part of the description.

[0014] Plasticizers selected from the following list, which can be used individually or in any mixture, have proven particularly suitable for improving elasticity: tributyl citrate, triethyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, polyvinyl alcohol, PEG-600, and sodium alginate. The aforementioned plasticizers not only improve the mechanical properties of synthetic hair, but are also environmentally friendly, thus improving the sustainability and environmental friendliness of the synthetic hair according to the invention. Among the aforementioned plasticizers, tributyl citrate has proven particularly suitable due to its good processability, good availability, and excellent adjustability of mechanical properties.

[0015] The aforementioned mechanical properties can be advantageously and easily adjusted in combination by using a plasticizer content of 20 to 50 mass%, and in particular 25 to 40 mass%, based on the total mass of the cellulose used for the cellulose fibers. The cellulose according to the invention is understood to be the "dry matter cellulose." If pulp or similar is used to provide the cellulose, all quantities refer to the dry matter of the cellulose, i.e., its dry content.

[0016] To match the shine of the synthetic hair to that of natural human hair, according to a further advantageous development, the cellulose fibers further comprise at least one matting agent. To further improve the skin-friendliness of the synthetic hair, the matting agent is preferably selected from SiO2, TiO2, MgO, CaCO3, MgCO3, BaSO4, and mixtures thereof. MgO and / or CaCO3, in particular, have proven to be particularly effective and skin-friendly.

[0017] Particularly advantageous in terms of good processability and a uniform, fine shine or even matte finish of the synthetic hair, the matting agent has a grain size of 0.01 to 1000 pm, particularly 0.1 to 30 pm, and especially 1 to 20 pm. Grain size determination is performed by laser diffraction using a HELOS device from Sympatec GmbH in accordance with ISO 13320 (publication date 2020).

[0018] Particularly good matting properties, which adapt the shine of the synthetic hair to the shine of real hair, can be achieved by the advantageous further development in which a proportion of matting agent, based on the total mass of the cellulose used for the cellulose fibers, is 0.1 to 20 mass%, in particular 5 to 17 mass% and in particular 7 to 15 mass%.

[0019] To visually match the synthetic hair to real hair or to create special color accents, the cellulose fibers advantageously further comprise at least one coloring substance. Coloring substances can include dyes and color pigments, which can be used in any combination. Carbon blacks can also be used according to the invention. Due to their high coloring power, pigments are particularly preferred, and the cellulose fibers therefore especially comprise at least one pigment.

[0020] Particularly good processability with high coloring power can be achieved by the design in which the proportion of coloring substance, based on the total mass of the cellulose used for the cellulose fibers, is 2 to 12 mass% and in particular 3 to 10 mass%.

[0021] Further advantageous for improving the optical and mechanical properties of the synthetic hair, the synthetic hair comprises a finish. According to the invention, a finish is understood to be a composition comprising at least one compound selected from the group consisting of fatty acids, fatty acid esters, fatty alcohols, fatty amines, fatty amides, polyquaterniums, polysiloxanes (including polydialkylsiloxanes), and polyols. Among the aforementioned compounds, fatty acids, fatty acid esters, fatty alcohols, fatty amines, and fatty amides are preferred due to their environmental friendliness, skin compatibility, and biodegradability.

[0022] Preferably, the diameter of the cellulose fibers in the synthetic hair is between 40 pm and 80 pm, and especially between 45 pm and 70 pm. If the diameter is within the specified range, it is very comparable to the diameter of real hair, so that a hair replacement product based on the synthetic hair according to the invention is also visually characterized by a high similarity to real hair. The diameter of the cellulose fibers can be measured using a micrometer screw.

[0023] Furthermore, the invention also discloses a method for producing the artificial hair described above, which is characterized by simple implementation and good environmental friendliness and thus also by high sustainability.

[0024] First, cellulose with a degree of polymerization of 100 to 450 is provided. The cellulose can be obtained, in particular, from wood pulp. The cellulose is then dissolved in a solvent, with N-methylmorpholine N-oxide being used as the solvent to improve environmental friendliness. A spinning solution comprising the dissolved cellulose is then prepared. Further additives can also be added to influence the spinnability or the properties of the cellulose fibers obtained after spinning. The spinning solution is then spun. Suitable spinning machines are known to those skilled in the art. The fibers obtained by the spinning process are then dried.

[0025] The process is simple and environmentally friendly, enabling a closed material cycle with minimal environmental impact. The fibers produced using this process are also biodegradable, increasing the sustainability of the synthetic hair while maintaining excellent skin compatibility. The resulting synthetic hair is characterized by excellent optical and mechanical properties similar to real hair, including a subtle luster, high fineness, good stretch properties, excellent elasticity, strength, and elongation at break, as well as a good knot tensile strength ratio.

[0026] It goes without saying that other common process steps can complement the process, such as the subsequent application of a conditioner. Furthermore, it goes without saying that the advantageous developments, effects, and configurations of the synthetic hair according to the invention and the process according to the invention are mutually applicable.

[0027] In order to adjust or improve the properties of the spun fibers during the spinning process without having to subsequently carry out further process steps, the preparation of the spinning solution preferably comprises a step of adding at least one plasticizer, wherein the plasticizer is selected in particular from tributyl citrate, triethyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, polyvinyl alcohol, PEG-600, sodium alginate and mixtures thereof, and in particular tributyl citrate. As already explained above for the synthetic hair according to the invention, by adding at least one plasticizer, in particular the tensile strength can be adjusted to a range of 8 to 16 cN / tex and the elongation to a range of 11 to 24%.In addition, by adding at least one plasticizer to the spinning solution, the elastic modulus can be adjusted to a range of 280 to 550 cN / tex and the knot tension ratio to 40 to 85%.

[0028] In particular, if according to a further advantageous development a proportion of plasticizer, based on the mass of dissolved cellulose, is 20 to 50 mass% and in particular 25 to 40 mass%, the above-mentioned mechanical properties can be obtained in combination, whereby the synthetic hair obtained is characterized by particularly good real hair-like mechanical properties.

[0029] In order to adjust the gloss or mattness and to colour the synthetic hair, it can further advantageously be provided that the production of the spinning solution comprises a step of adding at least one matting agent and / or at least one colouring substance.

[0030] Furthermore, the invention also describes the use of cellulose fibers, wherein the cellulose fibers comprise cellulose, wherein the cellulose from which the cellulose fibers are formed has a degree of polymerization of 100 to 450, and the cellulose fibers are used for the production of synthetic hair.

[0031] Furthermore, the use of cellulose fibers produced by the above process for the production of synthetic hair is also disclosed. For this purpose, the fibers have a fiber diameter of 40 to 80 pm, and especially 45 to 70 pm.

[0032] The present invention is explained below using examples, which, however, are not intended to limit the invention.

[0033] The grain size determination was carried out by laser diffraction using a HELOS device from Sympatec GmbH according to ISO 13320 (publication date 2020).

[0034] Fiber fineness was determined according to DIN EN ISO 1973 (1995), tensile strength and elongation were determined according to DIN EN ISO 5079 (2021), and the knot tensile test was carried out according to DIN 53842-1 (1976). The elastic modulus was also measured according to DIN EN ISO 5079 (2021) and read at 0.5 - 0.7%.

[0035] Cellulose fibers were produced using the following process sequence: a) Pretreatment: Powdered microcrystalline cellulose was provided. This was obtained from cellulose pulp that was first treated with chemicals to reduce its size and remove any excess fat. The cellulose had a degree of polymerization of 100 to 450. Suitable products can be obtained from Lehmann & Voss, for example, under the trade name Accel-102. b) Solvent extraction then took place: The cellulose was dissolved in a solvent, N-methylmorpholine N-oxide (NMMO). c) Spinning preparation: The solution was homogenized using a spinning preparation process and adjusted to the desired viscosity. d) Spinning: The solution was processed into fibers using a spinning process. e) Drying: The fibers are dried.

[0036] Thanks to the sustainable process using the NMMO solvent, it was almost completely recycled (recycling rate > 99%), thus improving the environmental friendliness of the resulting synthetic hair. The process was carried out using renewable raw materials, increasing the sustainability of the resulting synthetic hair. The resulting cellulose fibers were soft, tear-resistant, and abrasion-resistant.

[0037] Examples

[0038] The present invention is explained in more detail with reference to examples, but the invention is not intended to be limited to the examples.

[0039] Test methods for determining the textile-physical parameters of the produced cellulose fibres or synthetic hair:

[0040] Fiber fineness was determined according to DIN EN ISO 1973, tensile strength and elongation were determined according to DIN EN ISO 5079, and the knot tensile test was carried out according to DIN 53842-1. The knot tensile test examines the effects of shear forces on the filament. The samples are clamped in a knot-like manner and then analyzed for tensile strength. The highest possible knot tensile strength ratio corresponds to a flexible fiber; the lower it is, the more brittle the fiber. Only in this way is it possible to assess the above-described surface modification requirements regarding roughness (braidability) and softness (combability) using the method according to the invention.

[0041] Chemicals used:

[0042] - Eucalyptus PHK sulfate pulp (Sappi), degree of polymerization (DP) = 598

[0043] - Microcrystalline cellulose (Blanver), DP=290 - 320

[0044] - Citric acid tributyl ester (CAS: 77-94-1, Sigma-Aldrich)

[0045] - CaCO3, MgO (Magnesia)

[0046] - Fiber preparation: Polydimethylsiloxane (CAS: 63148-62-9)

[0047] - Printofix dyes (black, brown, red; Archroma)

[0048] Example 1

[0049] 6429 g of NMMO (58.3%), 487.1 g of spruce pulp (degree of polymerization, DP: 557, dry matter content, cellulose dry matter: 94.1%), 67.7 g of CaCO3, 2.9 g of propyl gallate (-0.63% based on the dry matter content, TG, of the cellulose), and 160.4 g of tributyl citrate (dry matter content, TG 100%, 35% based on the dry matter content, TG, of the cellulose) were homogenized and heated to approximately 90°C. The zero shear viscosity was 119 Pa*s. The cellulose had a degree of polymerization of 557. The resulting spinning solution was regenerated into filaments using the following spinning parameters:

[0050] Temperature of spin block and nozzle: 85°C

[0051] Spin bath temperature: 11-15°C

[0052] Spinning pump: 9.8 rpm Nozzle filter: 1x80 / 1 x800pm

[0053] Spinneret: 1x20 hole / 500 pm

[0054] Spinning speed: 35 m / min. The filament bundles were washed solvent-free, wound onto a reel, and finished with 0.6 g / l of fiber finish (polydimethylsiloxane). The bundles were hung to air dry. The bundles were combed to separate the filaments.

[0055] The assessment was carried out by measuring the textile physical parameters, haptics, braidability and combability.

[0056] Examples 2 - 9, 12, and 15: Filament bundles each produced according to Example 1, but with varying concentrations of tributyl citrate (TC) and / or other plasticizers. The results of the textile physical parameters compared to two types of human hair and two types of synthetic hair based on viscose and modacrylic (copolymer of vinyl chloride and acrylonitrile) are listed in Table 1.

[0057] Although increasing the concentration of the plasticizer tributyl citrate resulted in an improvement in tensile strength and elastic modulus, the good values ​​achieved for the viscose type were not achieved. Compared to the synthetic version and the real hair types, the elongation of examples 2-9, 12, and 15 was significantly lower, but the feel and matting were acceptable. The combination of the measured mechanical properties resulted in a synthetic hair with acceptable feel but less good combability, moldability, and drapability.

[0058] Example 16

[0059] Filament bundles were prepared according to Example 1, but with 6429 g of NMMO (58.3%), 719.6 g of microcrystalline cellulose (degree of polymerization, DP 300, dry matter content, TD of the cellulose 94.1%), 67.7 g of CaCO3, 4.27 g of propyl gallate (-0.63% based on the TD of the cellulose), and 169.3 g of tributyl citrate (TD 100%, 25% based on the TD of the cellulose). The cellulose had a degree of polymerization of 300.

[0060] Examples 17 - 20

[0061] Filament bundles produced according to Example 16, but with varying concentrations of tributyl citrate (TC). The results of the textile physical parameters compared to two types of human hair are listed in Table 2.

[0062] Table 2

[0063] The results of Examples 16-20 showed a significant increase in elongation and knot tensile strength ratio compared to the viscose type, as well as a corresponding decrease in the elastic modulus. Compared to the real hair types, the elongation values ​​were again somewhat lower, but the knot tensile strength ratio values ​​were at the same level.

[0064] The filament bundles of Examples 16 - 20 showed good haptics and braidability, which confirmed that the combability and formability were very good.

[0065] Example 21

[0066] Filament bundles produced according to Example 16, but with the addition of the following dyes: Printofix Black (TG 100%, 1.45% based on the cellulose TG); Printofix Brown (TG 100%, 3.3% based on the cellulose TG); and Printofix Red (TG 100%, 0.55% based on the cellulose TG). The filament bundles are characterized by a natural, warm, reddish-black color without gloss.

[0067] Examples 22 - 24

[0068] Filament bundles produced according to Example 16, but in addition to the above-mentioned fiber preparation (finishing), other types were used (0.6 g / l):

[0069] Example 16: Polydimethylsiloxane (CAS: 63148-62-9)

[0070] Example 22: N,N'-(iminodiethane-1,2-diyl)distearamide (CAS: 10220-90-3)

[0071] Example 23: Fatty alcohol ethoxylate (CAS: 68439-49-6)

[0072] Example 24: 9-Octadecenoic acid (Z)-, reaction products with triethanolamine, dimethyl sulfate quaternized (CAS 94095-35-9)

[0073] The evaluation was based on knot formation and combability (Table 3) after repeated moistening (washing).

[0074] Table 3

[0075] The fiber preparation based on polydimethylsiloxane proved particularly advantageous. Its ability to be braided with real hair was also rated positively.

[0076] Summarizing the examples, it was surprisingly found that, in particular, a combination of microcrystalline cellulose and high proportions of one or a combination of plasticizers enabled the production of cellulose-based synthetic hair with high flexibility, elasticity, and softness. The cellulose-based synthetic hair was characterized by high elongation at break and a high knot tensile strength ratio. According to the inventive process, extensibilities of the cellulosic filaments of more than 18% and knot tensile strength ratios of more than 60% and even over 80% were achieved. It was further found that a modification of the fiber surface integrated into the manufacturing process leads to filaments that have a pleasant feel and matte finish, as well as good separation (combability) and braiding into plaits.

[0077] A high plasticizer content of 30 to 40% based on the cellulose used for the cellulose fibers (here, according to the invention, reference is again made to the dry cellulose content) also led to a reduction in the density of the cellulose-based synthetic hair, which was very close to natural hair. Human hair has a density of approximately 1.3 g / cm³. 3 [CR Robbins: Chemical and Physical Behavior of Human Hair. (1994) Springer Verlag, New York, pp. 233-261]. The synthetic hairs according to the invention, which were produced using the method according to the invention, had a density in the range of 1.2 to 1.4 g / cm 3 .

Claims

Claims 1 . Synthetic hair comprising cellulose fibers, wherein the cellulose from which the cellulose fibers are formed has a degree of polymerization of 100 to 450.

2. Synthetic hair according to claim 1, wherein the cellulose from which the cellulose fibers are formed has a degree of polymerization of 200 to 400.

3. Synthetic hair according to claim 1 or 2, wherein the cellulose from which the cellulose fibers are formed comprises microcrystalline cellulose and in particular consists of microcrystalline cellulose.

4. Synthetic hair according to one of the preceding claims, wherein the cellulose fibers comprise at least one plasticizer, wherein the plasticizer is in particular selected from tributyl citrate, triethyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, polyvinyl alcohol, PEG-600, sodium alginate and mixtures thereof and in particular tributyl citrate.

5. Synthetic hair according to claim 4, wherein a proportion of plasticizer, based on the total mass of the cellulose used for the cellulose fibers, is 20 to 50 mass%, in particular 25 to 40 mass%.

6. Synthetic hair according to one of the preceding claims, wherein the cellulose fibers further comprise at least one matting agent, wherein the matting agent is in particular selected from SiO2, TiO2, MgO, CaCO3, MgCO3, BaSO4 and mixtures thereof and in particular MgO and / or CaCO3.

7. Synthetic hair according to claim 6, wherein the matting agent has a grain size of 0.01 to 1000 pm, in particular of 0.1 to 30 pm and in particular of 1 to 20 pm.

8. Synthetic hair according to claim 6 or 7, wherein a proportion of matting agent, based on the total mass of the cellulose used for the cellulose fibers, is 0.1 to 20 mass%, in particular 5 to 17 mass% and in particular 7 to 15 mass%.

9. Synthetic hair according to one of the preceding claims, wherein the cellulose fibers further comprise at least one coloring substance, in particular at least one pigment.

10. Synthetic hair according to claim 9, wherein a proportion of coloring substance, based on the total mass of the cellulose used for the cellulose fibers, is 2 to 12 mass%, in particular 3 to 10 mass%.

11. Synthetic hair according to one of the preceding claims, further comprising a finish comprising at least one compound selected from the group consisting of fatty acids, fatty acid esters, fatty alcohols, fatty amines, fatty amides, polyquaternium, polysiloxanes and polyols.

12. Synthetic hair according to one of the preceding claims, wherein a diameter of the cellulose fibers is 40 pm to 80 pm, in particular 45 pm to 70 pm.

13. A method for producing the artificial hair according to any one of the preceding claims, comprising the steps: Providing a cellulose with a degree of polymerization of 100 to 450 Dissolving the cellulose in a solvent, in particular in N-methylmorpholine-N-oxide Producing a spinning solution comprising the dissolved cellulose Spinning the spinning solution and Drying the fibers obtained from the spinning process.

14. The method according to claim 13, wherein the preparation of the spinning solution comprises a step of adding at least one plasticizer, wherein the plasticizer is in particular selected from tributyl citrate, triethyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, polyvinyl alcohol, PEG-600, sodium alginate and mixtures thereof and in particular tributyl citrate.

15. The method according to claim 14, wherein a proportion of plasticizer, based on the mass of the dissolved cellulose, is 20 to 50 mass%, in particular 25 to 40 mass%.

16. The method according to any one of claims 13 to 15, wherein the preparation of the spinning solution comprises a step of adding at least one matting agent and / or at least one coloring substance.

17. Use of cellulose fibers comprising cellulose, wherein the cellulose from which the cellulose fibers are formed has a degree of polymerization of 100 to 450, for the production of artificial hair.

18. Use of cellulose fibers produced by the process according to any one of claims 13 to 16 for the production of synthetic hair.

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