Flame-retardant PVC (polyvinyl chloride) power tube and production process thereof

Abstract

The invention relates to a flame-retardant PVC (polyvinyl chloride) power tube and a production process thereof, and belongs to the technical field of high polymer materials. The flame-retardant PVC power tube comprises the following components in parts by weight: 20-40 parts of polyvinyl chloride resin, 6-10 parts of a modified flame retardant, 6-10 parts of an anti-aging modifier, 3-7 parts of a lubricant, 3-5 parts of a heat stabilizer and 2-8 parts of a plasticizer, cyclohexanehexol phosphate in the modified flame retardant is heated and dehydrated into phosphoric acid, a barrier layer is formed, release of combustible materials is inhibited, an intermediate inhibits decomposition and combustion of PVC at high temperature, ammonia gas is generated during heating, combustible gas is diluted, and synergistic flame retardance is achieved with phosphorus-oxygen double bonds; 2, 4-dihydroxybenzophenone in the anti-aging modifier generates thermal vibration and releases energy after being irradiated by ultraviolet rays, and a maleimide group improves the glass transition temperature and the melting point and reduces aging caused by high-temperature thermal aging; the flame-retardant PVC electric power tube prepared by the invention not only has an excellent flame-retardant effect, but also has good aging resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a flame-retardant PVC electric power pipe and a production process thereof. Background Art

[0002] With the rapid progress of science and technology and the vigorous development of industry, polyvinyl chloride (PVC) pipes have good compressive and tensile strength, and have shown increasingly wide application potential in pressure-bearing sanitary pipes and fittings in urban construction, water supply and drainage pipes and fittings for buildings, porous casings for electricity, high-voltage cable pipes, natural gas pipes, etc.

[0003] However, in high temperature environments, PVC power pipes may soften, and continuous temperature fluctuations will accelerate the aging process of the pipes. At the same time, during the laying process, traditional PVC power pipes will be exposed to strong ultraviolet radiation under the sunlight, which will cause the molecular structure to be destroyed and further ageing of the material. Therefore, anti-aging performance has also become an indispensable characteristic of PVC power pipes. In addition, although PVC power pipes have a certain flame retardant effect when they burn, with the increase in actual application needs, their own flame retardancy can no longer meet the needs. Therefore, the research and development of PVC power pipes with excellent anti-aging and flame retardant properties has important practical significance and application value. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a flame-retardant PVC electric power pipe and a production process thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A flame-retardant PVC electric power pipe comprises the following raw materials in parts by weight: 20-40 parts of polyvinyl chloride resin, 6-10 parts of modified flame retardant, 6-10 parts of anti-aging modifier, 3-7 parts of lubricant, 3-5 parts of heat stabilizer, and 2-8 parts of plasticizer; The heat stabilizer is zinc stearate; The lubricant is butyl stearate; The plasticizer is dioctyl phthalate.

[0006] The modified flame retardant is prepared by the following method: Step A1: melamine, formaldehyde and deionized water are mixed uniformly, the pH is adjusted to 8-9, mechanically stirred at 80° C. for 40 min, cooled to room temperature, filtered, and dried at 80° C. to obtain an intermediate; Further, the dosage ratio of melamine, formaldehyde and deionized water is 1.2-1.4 g: 1.8-2.1 g: 10-20 mL; First, the amino group of melamine reacts with formaldehyde to generate an intermediate; Step A2: The intermediate and cyclohexanehexol phosphate are mixed and stirred, the temperature is raised to 60° C., 4-dimethylaminopyridine is added and stirred, the mixture is kept at 60° C. for 3 h, and the mixture is cooled to room temperature to obtain a pre-product; Further, the usage ratio of the intermediate, cyclohexanehexol phosphate, and 4-dimethylaminopyridine is 1.5-2.0 g: 1.3-1.8 g: 20-45 mL; Secondly, the hydroxyl group of the intermediate reacts with the hydroxyl group of cyclohexanehexanol phosphate to generate a pre-product; Step A3: The pre-product, 6-chloro-1-hexene and methanol were mixed, stirred for 20 minutes, heated to 80°C for reaction for 1 hour, and when the temperature dropped to room temperature, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and N,N-dimethylformamide were added, mixed, stirred at 150°C for 9 hours, filtered at room temperature, washed, and vacuum dried at 60°C for 24 hours to obtain a modified flame retardant; Further, the usage ratio of the preproduct, 6-chloro-1-hexene, methanol, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and N,N-dimethylformamide is 1-2 mol: 2-4 mol: 5-10 mL: 2-4 mol: 180-200 mL; Finally, the chlorine atom of 6-chloro-1-hexene reacts with the hydroxyl group of the pre-product, and the carbon-carbon double bond of 6-chloro-1-hexene reacts with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to generate a modified flame retardant.

[0007] The anti-aging modifier is prepared by the following method: Step B1: maleic anhydride, toluene and 3-chloroaniline were mixed, stirred for reaction for 30 minutes, tetrahydrofuran was added, and stirring was continued for 5 minutes in an ice-water bath, triethylamine was added and mixed, and the mixture was reacted for 10 minutes, washed, dried, filtered, and rotary evaporated to obtain a compound; Further, the dosage ratio of maleic anhydride, toluene, 3-chloroaniline, tetrahydrofuran, and triethylamine is 4.81-5.75 g: 40-50 mL: 6.2-6.4 g: 10 mL: 3.12-4.58 g; First, maleic anhydride is reacted with the amino group of 3-chloroaniline to generate a compound; Step B2: 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran are mixed evenly, and then the compound is added dropwise in an ice bath for 1-2 hours, and the mixture is reacted in an ice bath for 5 hours. After the reaction is completed, the mixture is precipitated in ice water, washed, and vacuum dried to obtain an anti-aging modifier; Further, the usage ratio of 2,4-dihydroxybenzophenone, triethylamine, tetrahydrofuran, and compound is 2.14-5.35 g: 1.7-3.5 mL: 20-30 mL: 0.01-0.05 mol; The hydroxyl group of 2,4-dihydroxybenzophenone reacts with the chlorine atom of the compound to generate an anti-aging modifier.

[0008] A production process of a flame-retardant PVC power pipe specifically comprises the following steps: Step S1: mixing polyvinyl chloride resin, modified flame retardant, anti-aging modifier and heat stabilizer, stirring for 2-2.5 hours at a temperature of 175-180° C. and a rotation speed of 200 r / min to obtain a mixture; Step S2: adding a lubricant and a plasticizer to the mixture, stirring for 3-4 hours at a temperature of 180-190° C. and a rotation speed of 500 r / min to obtain a pre-material; Step S3: Add the pre-material into a conical twin-screw extruder, extrude, shape and cut at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe.

[0009] Beneficial effects of the present invention: The flame-retardant PVC electric power pipe of the present invention uses polyvinyl chloride resin as a matrix, to which a modified flame retardant and an anti-aging modifier are added, thereby giving the material excellent anti-aging performance and flame retardancy, and effectively extending the service life of the material.

[0010] The cyclohexanehexol phosphate in the modified flame retardant prepared by the present invention is a biomass renewable resource with a wide source and is environmentally friendly. It is dehydrated into phosphoric acid when heated, which promotes surface carbonization to form a barrier layer, effectively isolates air and heat, inhibits the release of combustible volatiles, and achieves a flame retardant effect; the intermediate has high thermal stability and can maintain structural integrity at high temperatures, thereby effectively inhibiting the decomposition and combustion of PVC at high temperatures. At the same time, the intermediate will decompose and produce ammonia when heated, dilute the combustible gas, and prevent the further spread of the flame; in addition, the phosphorus-nitrogen flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphaphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous carbon layer during combustion, effectively isolates oxygen, blocks heat and combustible gas exchange, inhibits combustion, and also cooperates with the phosphorus-oxygen double bond to achieve flame retardancy, thereby extending its service life; in addition, the composite flame retardant prepared by the present invention is halogen-free, helps to reduce environmental pollution and damage to the ecosystem, is harmless to human health, and achieves sustainable development.

[0011] In the anti-aging modifier prepared by the invention, hydrogen bonds can be formed between hydroxyl hydrogen and carbonyl oxygen in 2,4-dihydroxybenzophenone to form a chelate ring. When irradiated with ultraviolet rays, the molecule undergoes thermal vibration, and electrons in the molecule are excited to transition to a higher energy level, and then release energy in the form of weak long-wave emission, thereby avoiding the harm of high-energy ultraviolet rays. Meanwhile, the molecular structure of 2,4-dihydroxybenzophenone contains a benzene ring and a methoxy group, which can effectively absorb ultraviolet rays. In addition, the maleimide group can enhance the intermolecular force, increase the glass transition temperature and melting point of the material, increase the rigidity and heat resistance of the molecular chain, and reduce the aging of the material caused by high-temperature thermal aging. In addition, the anti-aging modifier has high compatibility with polyvinyl chloride, and solves the migration, incompatibility and volatilization problems of traditional anti-aging modifiers. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] Embodiment 1: A production process of a flame-retardant PVC power pipe, comprising the following steps: Step S1: weighing raw materials by weight, 20 parts of polyvinyl chloride resin, 6 parts of modified flame retardant (prepared in this embodiment), 6 parts of anti-aging modifier (prepared in this embodiment), 3 parts of lubricant, 3 parts of heat stabilizer, and 2 parts of plasticizer; mixing polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, stirring for 2 hours at a temperature of 175° C. and a rotation speed of 200 r / min to obtain a mixture; Step S2: adding butyl stearate and dioctyl phthalate to the mixture, stirring for 3 hours at a temperature of 180° C. and a rotation speed of 500 r / min to obtain a pre-material; Step S3: adding the pre-material into a conical twin-screw extruder, extruding, shaping, and cutting at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe; The modified flame retardant is prepared by the following method: Step A1: 1.2 g of melamine, 1.8 g of formaldehyde and 10 mL of deionized water were mixed uniformly, the pH was adjusted to 8, mechanically stirred at 80° C. for 40 min, cooled to room temperature, filtered, and dried at 80° C. to obtain an intermediate; Step A2: 1.5 g of the intermediate and 1.3 g of cyclohexanehexol phosphate were mixed and stirred, the temperature was raised to 60° C., 20 mL of 4-dimethylaminopyridine was added and stirred, the mixture was kept at 60° C. for 3 h, and cooled to room temperature to obtain a pre-product; Step A3: 1 mol of the pre-product, 2 mol of 6-chloro-1-hexene and 5 mL of methanol were mixed, stirred for 20 min, heated to 80 ° C for reaction for 1 h, and when the temperature dropped to room temperature, 2 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 180 mL of N,N-dimethylformamide were added, stirred at 150 ° C for 9 h, filtered at room temperature, washed, and vacuum dried at 60 ° C for 24 h to obtain a modified flame retardant; The anti-aging modifier is prepared by the following method: Step B1: 4.81 g of maleic anhydride, 40 mL of toluene and 6.2 g of 3-chloroaniline were mixed, stirred for reaction for 30 min, 10 mL of tetrahydrofuran was added, and stirring was continued for 5 min in an ice-water bath, and 3.12 g of triethylamine was added and mixed, and the mixture was reacted for 10 min, washed, dried, filtered, and rotary evaporated to obtain a compound; Step B2: 2.14 g of 2,4-dihydroxybenzophenone, 1.7 mL of triethylamine and 20 mL of tetrahydrofuran were mixed evenly, and then 0.01 mol of the compound was added dropwise in an ice bath for 1 h. The reaction was carried out in an ice bath for 5 h. After the reaction was completed, the mixture was precipitated in ice water, washed, and vacuum dried to obtain an anti-aging modifier.

[0014] Embodiment 2: A production process of a flame-retardant PVC power pipe, comprising the following steps: Step S1: weighing raw materials by weight, 30 parts of polyvinyl chloride resin, 8 parts of modified flame retardant (prepared in this embodiment), 8 parts of anti-aging modifier (prepared in this embodiment), 5 parts of lubricant, 4 parts of heat stabilizer, and 5 parts of plasticizer; mixing polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, stirring for 2.2 hours at a temperature of 177° C. and a rotation speed of 200 r / min to obtain a mixture; Step S2: adding butyl stearate and dioctyl phthalate to the mixture, stirring for 3.5 hours at a temperature of 185° C. and a rotation speed of 500 r / min to obtain a pre-material; Step S3: adding the pre-material into a conical twin-screw extruder, extruding, shaping, and cutting at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe; The modified flame retardant is prepared by the following method: Step A1: 1.3 g of melamine, 1.95 g of formaldehyde and 15 mL of deionized water were mixed uniformly, the pH was adjusted to 8.5, mechanically stirred at 80° C. for 40 min, cooled to room temperature, filtered, and dried at 80° C. to obtain an intermediate; Step A2: 1.75 g of the intermediate and 1.55 g of cyclohexanehexol phosphate were mixed and stirred, the temperature was raised to 60° C., 32.5 mL of 4-dimethylaminopyridine was added and stirred, the mixture was kept at 60° C. for 3 h, and cooled to room temperature to obtain a pre-product; Step A3: 1.5 mol of the pre-product, 3 mol of 6-chloro-1-hexene and 7.5 mL of methanol were mixed, stirred for 20 min, heated to 80° C. for reaction for 1 h, and when the temperature dropped to room temperature, 3 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 190 mL of N,N-dimethylformamide were added, mixed, stirred at 150° C. for 9 h, filtered at room temperature, washed, and dried in vacuum at 60° C. for 24 h to obtain a modified flame retardant; The anti-aging modifier is prepared by the following method: Step B1: 5.28 g of maleic anhydride, 45 mL of toluene and 6.3 g of 3-chloroaniline were mixed, stirred for reaction for 30 min, 10 mL of tetrahydrofuran was added, and stirring was continued for 5 min in an ice-water bath, and 3.85 g of triethylamine was added and mixed, and the mixture was reacted for 10 min, washed, dried, filtered, and rotary evaporated to obtain a compound; Step B2: 3.745 g of 2,4-dihydroxybenzophenone, 2.6 mL of triethylamine and 25 mL of tetrahydrofuran were mixed evenly, and then 0.03 mol of the compound was added dropwise in an ice bath for 1.5 h. The mixture was reacted in an ice bath for 5 h. After the reaction, the mixture was precipitated in ice water, washed and dried in vacuum to obtain an anti-aging modifier.

[0015] Embodiment 3: A production process of a flame-retardant PVC power pipe, comprising the following steps: Step S1: weighing raw materials by weight, 40 parts of polyvinyl chloride resin, 10 parts of modified flame retardant (prepared in this embodiment), 10 parts of anti-aging modifier (prepared in this embodiment), 7 parts of lubricant, 5 parts of heat stabilizer, and 8 parts of plasticizer; mixing polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, stirring for 2.5 hours at a temperature of 180° C. and a rotation speed of 200 r / min to obtain a mixture; Step S2: adding butyl stearate and dioctyl phthalate to the mixture, stirring for 4 hours at a temperature of 190° C. and a rotation speed of 500 r / min to obtain a pre-material; Step S3: adding the pre-material into a conical twin-screw extruder, extruding, shaping, and cutting at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe; The modified flame retardant is prepared by the following method: Step A1: 1.4 g of melamine, 2.1 g of formaldehyde and 20 mL of deionized water were mixed evenly, the pH was adjusted to 9, mechanically stirred at 80° C. for 40 min, cooled to room temperature, filtered, and dried at 80° C. to obtain an intermediate; Step A2: 2.0 g of the intermediate and 1.8 g of cyclohexanehexol phosphate were mixed and stirred, the temperature was raised to 60° C., 45 mL of 4-dimethylaminopyridine was added and stirred, the mixture was kept at 60° C. for 3 h, and cooled to room temperature to obtain a pre-product; Step A3: 2 mol of the pre-product, 4 mol of 6-chloro-1-hexene and 10 mL of methanol were mixed, stirred for 20 min, heated to 80 ° C for reaction for 1 h, and when the temperature dropped to room temperature, 4 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 200 mL of N,N-dimethylformamide were added, stirred at 150 ° C for 9 h, filtered at room temperature, washed, and vacuum dried at 60 ° C for 24 h to obtain a modified flame retardant; The anti-aging modifier is prepared by the following method: Step B1: 5.75 g of maleic anhydride, 50 mL of toluene and 6.4 g of 3-chloroaniline were mixed, stirred for reaction for 30 min, 10 mL of tetrahydrofuran was added, and the mixture was stirred for 5 min in an ice-water bath, and 4.58 g of triethylamine was added and mixed, and the mixture was reacted for 10 min, washed, dried, filtered, and rotary evaporated to obtain a compound; Step B2: 5.35 g of 2,4-dihydroxybenzophenone, 3.5 mL of triethylamine and 30 mL of tetrahydrofuran were mixed evenly, and then 0.05 mol of the compound was added dropwise in an ice bath for 2 h. The reaction was carried out in an ice bath for 5 h. After the reaction was completed, the mixture was precipitated in ice water, washed, and vacuum dried to obtain an anti-aging modifier.

[0016] Comparative Example 1 This comparative example is a flame-retardant PVC electric power pipe, which differs from Example 3 in that an equal amount of magnesium hydroxide is used to replace the modified flame retardant prepared in Example 3, and the rest are the same.

[0017] Comparative Example 2 This comparative example is a flame-retardant PVC power pipe, which is different from Example 3 in that an equal amount of 4,4'-thiobis(6-tert-butyl-3-methylphenol) is used to replace the anti-aging modifier prepared in Example 3, and the rest are the same.

[0018] Performance test: The flame-retardant PVC power pipes prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes, and the vertical burning performance was tested using the GB / T2048-1996 plastic combustion performance test method; a UVC-LED disinfection lamp (30W, 254nm wavelength) was used to irradiate for 40 hours at a vertical distance of 10cm, and the color difference before and after UVC-LED irradiation was detected using the CIE1976L*a*b* standard; the samples were placed in a UV aging box under the conditions of 60°C, 0.86w / cm2, and ultraviolet light for 1000h, and the difference in yellow index change was tested. The larger the difference, the worse the anti-aging performance; the test results are shown in Table 1 below: Table 1

[0019] It can be seen from the test data in Table 1 that the flame-retardant PVC power pipe prepared in Example 1 has excellent flame-retardant properties. It can also be seen from the above table that the flame-retardant PVC power pipe prepared in the present invention has good UV resistance and aging resistance.

[0020] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A production process for flame-retardant PVC power pipe, characterized in that: The following steps are involved: Step S1: weighing raw materials by weight, 20-40 parts of polyvinyl chloride resin, 6-10 parts of modified flame retardant, 6-10 parts of anti-aging modifier, 3-7 parts of lubricant, 3-5 parts of heat stabilizer, and 2-8 parts of plasticizer; mixing the polyvinyl chloride resin, modified flame retardant, anti-aging modifier and heat stabilizer, stirring for 2-2.5 hours at a temperature of 175-180° C. and a rotation speed of 200 r / min to obtain a mixture; Step S2: adding a lubricant and a plasticizer to the mixture, stirring for 3-4 hours at a temperature of 180-190° C. and a rotation speed of 500 r / min to obtain a pre-material; Step S3: adding the pre-material into a conical twin-screw extruder, extruding, shaping, and cutting at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe; The modified flame retardant is prepared by the following method: Step A1: melamine, formaldehyde and deionized water are mixed uniformly, the pH is adjusted to 8-9, mechanically stirred at 80° C. for 40 min, cooled to room temperature, filtered, and dried at 80° C. to obtain an intermediate; Step A2: The intermediate and cyclohexanehexol phosphate are mixed and stirred, the temperature is raised to 60° C., 4-dimethylaminopyridine is added and stirred, the mixture is kept at 60° C. for 3 h, and the mixture is cooled to room temperature to obtain a pre-product; Step A3: The pre-product, 6-chloro-1-hexene and methanol were mixed, stirred for 20 minutes, heated to 80°C for reaction for 1 hour, and when the temperature dropped to room temperature, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and N,N-dimethylformamide were added and mixed, stirred at 150°C for 9 hours, filtered at room temperature, washed, and vacuum dried at 60°C for 24 hours to obtain a modified flame retardant.

2. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that: In step A1, the usage ratio of melamine, formaldehyde and deionized water is 1.2-1.4 g: 1.8-2.1 g: 10-20 mL.

3. The production process of a flame-retardant PVC electric power pipe according to claim 1, characterized in that: The usage ratio of the intermediate, cyclohexanehexol phosphate and 4-dimethylaminopyridine in step A2 is 1.5-2.0 g: 1.3-1.8 g: 20-45 mL.

4. The production process of a flame-retardant PVC electric power pipe according to claim 1, characterized in that: In step A3, the usage ratio of the preproduct, 6-chloro-1-hexene, methanol, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and N,N-dimethylformamide is 1-2 mol: 2-4 mol: 5-10 mL: 2-4 mol: 180-200 mL.

5. The production process of a flame-retardant PVC electric power pipe according to claim 1, characterized in that: The anti-aging modifier is prepared by the following method: Step B1: maleic anhydride, toluene and 3-chloroaniline were mixed, stirred for reaction for 30 minutes, tetrahydrofuran was added, and stirring was continued for 5 minutes in an ice-water bath, triethylamine was added and mixed, and the mixture was reacted for 10 minutes, washed, dried, filtered, and rotary evaporated to obtain a compound; Step B2: 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran are mixed evenly, and then the compound is added dropwise in an ice bath for 1-2 hours. The reaction is carried out in an ice bath for 5 hours. After the reaction is completed, the mixture is precipitated in ice water, washed, and vacuum dried to obtain an anti-aging modifier.

6. The production process of a flame-retardant PVC electric power pipe according to claim 5, characterized in that: In step B1, the usage ratio of maleic anhydride, toluene, 3-chloroaniline, tetrahydrofuran and triethylamine is 4.81-5.75 g: 40-50 mL: 6.2-6.4 g: 10 mL: 3.12-4.58 g.

7. The production process of a flame-retardant PVC electric power pipe according to claim 5, characterized in that: In step B2, the usage ratio of 2,4-dihydroxybenzophenone, triethylamine, tetrahydrofuran and compound is 2.14-5.35 g: 1.7-3.5 mL: 20-30 mL: 0.01-0.05 mol.

8. The production process of a flame-retardant PVC electric power pipe according to claim 1, characterized in that: The heat stabilizer is zinc stearate, the lubricant is butyl stearate, and the plasticizer is dioctyl phthalate.

9. A flame retardant PVC power pipe, characterized in that: Prepared according to the production process according to any one of claims 1 to 8.

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