Subject of invention is the multi-layer composite sleeve, in particular for trenchless pipeline rehabilitation.

There is growing interest fields and demand in many technical for environment friendly products (“green”) and programs for dangerous material removing, in particular from residential and workplace environment. Demand for “green” products replacing petrochemical plastics and dangerous polymers results from ecological awareness and necessity to improve health conditions of life. Material of biological origin is perceived as perfect solution on architectural, institutional, commercial and even residential market. It is important that materials and products in this environment should not have been harmful for general human health and ensure clean environment free from toxic chemicals.

In US8652617B2 patent specification, solution of bio-laminate composite set including polylactic acid and natural wax laminate layer and related manufacturing methods thereof was presented. Bio-laminate composite sets may comprise one or more bio-laminate layers and at least one bio-laminate layer may comprise polylactic acid. In one embodiment, bio-laminate composite set comprising one or more bio-laminate layers is provided, wherein bio-laminate composite set may be formed in three dimensions on rigid non-plastic substrate. At least one of bio-laminate layers comprises polylactic acid and natural wax. In bio-laminates, layers comprising various natural minerals, such as silica (natural quartz), aluminum oxide, calcium carbonate and other minerals can be used for flooring product manufacturing in order to provide higher degree of wear resistance and hardness. These wear-resistant materials may have form of medium-size particles which may be perceived visually as decorative and functional particles. Such fine-grain material becomes clarified or semi-transparent in bio-copolymer matrix or in nano-granular form in bio- laminate layer.

In EP3400331A1 patent specification problem of toxicity eliminating was undertaken through using water dispersion of: (a) basic resin comprising at least one double bond of polyolefin C2-C3 with melting point at least 110 ° C; and (b) dispersant comprising at least one polymer comprising ethylene and carboxylic acid, modifying polymer comprising at least one maleate, polyolefin wax C2-C3 or combination thereof; wherein elastic impregnated article has bending module smaller than 15 000 psi.

In FR2520021A1 patent specification the composite linings for new or damaged pipes - including resin impregnated non-woven fabrics and strong woven fabric layers were disclosed. Elastic film applied on internal surface may be of natural or butyl rubber, polyethylene or elastic PVC. Non-woven fabrics may be made of natural materials such as cotton or synthetic fibers, such as polyester. Non-woven fabric layers may be made of similar or different materials and/or thickness. Reinforcement may be made of woven fabric or mesh fabric, in particular of glass fibers at preferred alignment such that warp and weft fibers to be aligned suitably with axe and pipe radia.

From GB2541285A patent specification in which possibility of natural plant fiber using was disclosed, the structural lining for reinforcing existing underground water canals is known. Curing resin may be curing resin such as epoxy resin, unsaturated polyester resin, resin based vinyl-ester based resin or urethane-based resin or thermoplastic resin such as polyolefin, polyethylene, polyethylene terephthalate (PET) or technical resin such as polyamide (NYLON), etc.. Fiber yam may be made of polyester fibers, glass fibers, carbon fibers, aramide fibers, natural fibers such as cellulose fibers, such as linen or hemp fibers, oriented polyethylene fibers, polyamide fibers or polypropylene fibers.

Using of treated different fibrous plants for manufacturing at least components of threads, woven fabrics, mat fabrics, alternatively non-woven fabrics or felt fabrics is known from technical practice. Natural fiber treatment processes are known from various publications.

Lignocellulosic fibrous materials are widely used in various applications and have many advantages, including fact that they are relatively inexpensive as compared, e.g., with fibers made of synthetic plastic. Basically, lignocellulosic fibers absorb moisture very strongly and this is first significant drawback of using these fibers. Lignocellulosic fibers tend also to have lack of stability and strength and therefore they standalone do not constitute significant substitute for synthetic fibers which have greater stability and strength.

To make them 'acetylated' fibers - acetylation was proposed. In EP0213252 patent specification, fiber treatment acetylation process used for wood fibers was disclosed, and treatment improves lignocellulosic material dimensional stability and biological immunity to be decomposed. Basic acetylation process relies on using acetic anhydride for changing basic chemistry of cellular wall polymers. In particular, in reference to constituents of cellulose and hemicellulose, for example, highly specific biological enzymatic reactions may not occur because chemical configuration and molecular conformation of substrate was changed. Using reactive chemicals to fill cellular wall polymers reduces fiber tendency to bulge along with moisture variations provided that lignocellulosic material becomes partly if not completely - bulged. In this solution for hydroxyl group esterification in cellular wall acetic anhydride is used what results in resistance to organism attack and improved dimensional stability. Using the acetylated lignocellulosic fibers is very limited for various reasons, also for the fact that acetylation process includes toxic materials using which have to be effectively removed or neutralized.

Jute fiber acetylation was also tested (Mona Anderssen i AM Tillman, Journal of Applied Polymer Sciences, tom 37, 3437, 1989).

From WQ9719979A1 patent specification, lignocellulosic materials are known, in particular natural fibers such as jute, used advantageously as dispersed in curing synthetic resin in sheet structures.

Acetylated fibers, in particular, but not exclusively, jute fibers, are aligned as a composite portion in form of elastic sheet material which second portion is viscous mass of type comprising at least curing resin component such that sheet material may be formed and mass may be stiffened (when thermoplastic resin is used) and cured (when thermo-curing resin is used) to stiff form including acetylated fibers comprised therein and obtained composite may be applied as elastic piping structure which may be inflated to form the pipe. Comparing conventional polyester fiber linings with linings made solely of acetylated fibers, in particular made of jute fibers, it was found that linings according to invention are not only cheaper but even stronger by 50%. Acetylated fibers have empty' spaces on surface which are filled with resin, thus bonds between fibers and resin becomes stronger. To improve bonding between fibers and resin, fibers can be earlier subjected to cleansing by epoxy solvent and then drying.

It is possible to use mixtures of acetylated fibers and conventional fibers. Fibers may be in form of yams which are extending circumferentially on pipe structure, and in such case yams may be initially impregnated with resin which is the same or compatible with resin used for pipe structure, so they are effectively bonded together. Fibers of yams may be acetylated before or after forming in yarn. Fiber acetylation may be executed by any manner, e.g., known from WO9801497A1 patent specification which relates to various methods of lignocellulosic fiber acetylation, such as jute, hemp, wood fibers, sisal, tow, straw and such like. Fibers can be of any length but there is relation between fiber length and tensile strength of sheet material (before stiffening) and therefore using of longer fibers such as jute fibers will be preferred.

In CN104420177A patent specification method jute fiber bleaching method which selectively removes lignin from jute fiber superficial layer was disclosed. Jute fiber superficial layers are treated with sodium hypochlorite solution with pH from 6 to 6,5 and then they are subjected to treating with sodium hypochlorite with pH 10,5-11 to extract chlorinated lignin and to facilitate hydrogen peroxide activating in the process of boiling with hydrogen peroxide with pH 10,5-11.

In CN102493165 A patent specification jute fiber bleaching method is disclosed which includes: original jute processing into jute fibers and composition preparing of sodium sulfite, sodium bisulfite and peroxyacetic acid with mass of 3-16% by weight of jute fiber in solution for bleaching treatment in accordance with weight ratio of the bath 1:15-30 and bleaching treatment. Liquid temperature is raised up to 60-90 °c and then jute fibers are introduced thereto in order to soak them for 20-60 minutes. To above bleaching solution hydrogen peroxide of 3-16% by weight and bleaching stabilizer of 0,5-8% by weight are added, while maintaining temperature within 60-90 °C, jute fibers are still soaked within 20-60 min. Preferably, bleaching stabilizer is stabilizer 106, oxygen bleaching stabilizer FT, hydrogen peroxide or Prestogen EB. The cheapest bleaching agent for plant fiber bleaching is technical sodium hypochlorite which contains appr. 200 g of active chlorine in 1 liter of solution. Sodium hypochlorite brings good bleaching effect and ability for delignification but during bleaching it generates various toxic substances what results in serious environment pollution. It was proved that at bleaching by chlorine and sodium hypochlorite bleaching sewages contain many organic halides including dioxins and AOX which are harmful for human health and environment, therefore international ban for chlorine bleaching method using is in force.

For bleaching, stabilized 35% water solution of hydrogen peroxide called also as perhydrol is frequently used. It is dense, colorless liquid with strong oxidizing effect. Product is available usually in 35 % or 50 % concentration. Although bleaching by hydrogen peroxide is environment friendly bleaching method, however it has weak lignin removing effect. Therefore, hydrogen peroxide is frequently used in fiber bleaching process with smaller amount of lignin. Jute bleached in normal bleaching process has this drawback that it easily becomes yellow in sunlight because lignin present in jute easily absorbs UV light at wavelength of 330-370 nm forming colorful substance which causes yellowing. From JP2020020082 patent specification bleaching method of woven fabric comprising plant fibers in which woven fabric is exposed to UV radiation during processing the woven fabric with ozonized water in which material is cotton woven fabric or linen woven fabric is known. Treatment with ozonized water is carried out by means of continuous passing ozonized water through woven fabric. Reducing agent making color return is sodium hydroxymetanosulfinian.

In CN103321033A patent specification bamboo fiber yarn bleaching process is disclosed which includes dyeing tank heating up to 90°C to which 100 parts of yarn by weight and 10- 15 parts by weight of bleaching agent is added. Bath ratio is 1: 10-15 and bath is continued within 20-50 minutes. Bleaching agent includes hydrogen peroxide, hydrogen peroxide stabilizer and refining agent, wherein hydrogen peroxide concentration is 27,5%, and weight ratio of above hydrogen peroxide, hydrogen peroxide stabilizer and refining agent is 10:1:2. Yarn bleached by method according to this invention has whiteness over 90% and tenacity of 60cN/tex. In CN 109056302A patent specification, soya protein fiber bleaching method in low temperature was disclosed. Soya fiber is a kind of regenerated protein plant fiber which is made of soya sludge and soya pellet in soya oil post-extraction process.

Soya meal is refined by water leaching to remove protein. Obtained protein structure is changed and it is dinged by hydroxyl and cyanic polymer to prepare suitable conditions of defined solution concentration for protein wet spinning after ripening. Soya textile fibers with various lengths may be made after obtaining the fiber properties stabilized by hydroformylation, after crimping, heat-setting and cutting. Soya protein fiber has low density, high elongation, good resistance to acid and base and also capability for spinning. Fiber properties are similar to those of cotton, wool, hemp and silk.

The objective of invention is to produce the "environment friendly" sleeve comprising plant fibers in composite composition, with greater transmittance for light radiation, in particular within UV range and having layered structure, meeting the resistance requirements to transverse pressing on the cured sleeve in the repaired pipeline.

Essence of invention

In multi-layer composite sleeve solution, in particular for trenchless pipeline rehabilitation which has internal film layer and alternatively external protective layer, intermediate mineral fiber, organic, alternatively non-organic layers which these layers are in form of woven, quilted, felted, combed, directional fibers, alternatively loose fibers applied irregularly on preceding layers, stitched together or shifted with longitudinal edges overlapping on adjacent layers and soaked with curing resins with polymerization initiators, wherein alternatively: as the internal film layer it has elastic synthetic films with high degree of light transmittance: PE, HDPE, MDPE, PA/PE, integrated, or biodegradable films; as mineral fibers it has glass, basalt, metal fibers; as organic fibers it has plant fibers of linen, hemp, sisal, jute, cotton, kenaf, abaca, ramia, bamboo, coconut, bagasse sugar cane, castor, soya, Attacus atlas silkworm fibers, or at least two of them, subjected to preparatory chemical treatment and alternatively, to acetylation; as synthetic fibers it has polypropylene, Kevlar, polyester, aramid, polyethylene, terylene, viscose, polyesteramide fibers, or at least two of them; having polymers susceptible to UV radiation photo initiation, the essence is that it has discolored plant fibers in amount of 1% to 80% laminate mass by weight, preferably pre- reinforced with synthetic plastic layer and/or discolored plant fibers pre-reinforced by parallel mineral or synthetic fibers having intermediate layers I÷IV with woven fabrics, mat fabrics, braided fabrics, non-woven fabrics or felt fabric structure.

Preferably, in intermediate layers I÷IV it has variable amount of 0-100 % of discolored fibers by weight relative to fiber amount, preferably polyacrylonitrile fibers, and most preferably mixture of 10-90% mineral fibers. Preferably, in subsequent intermediate layers I÷IV it has percentage amount of discolored fibers increasing from intermediate layer I with the smallest circumference to intermediate layer IV with the greatest circumference, most preferably comprising basalt fibers. Preferably, in adjacent intermediate layers I÷IV it has different structure of discolored fibers, most preferably in combination with fibers. Preferably, it has discolored fibers obtained from preparatory chemical treatment of known fiber bleaching. Preferably, it has wear-resistant layer on intermediate layer I surface adjacent to internal film layer, most preferably of quartz sand and/or in form of nano-granular silica.

The utilizing of bleached plant fibers with reduced amount of chemical substances comprised in plants is advantageous effect of solution according to invention. During experiments it turned out unexpectedly that all laminate layers were cured relatively quickly, and thus increased UV radiation transmittance from the lamps of the device moved inside of inflated sleeve was obtained due to greater number of intermediate layers, also to sleeve layers proximate to internal surface of the repaired pipeline. Thanks to that resin polymerization process in the composite external sleeve layers distanced from radiation sources is accelerated, and simultaneously, whole pipeline repairing process energy consumption, associated with maintaining of pressure inflating sleeve up to the moment of total sleeve curing is decreased.

Obtained effect may be explained on the base of plant physiology investigations. In literature (J. Pilarski i in., Plant adaptation to spectral composition and radiation intensity, Plant Physiology Institute, PAN in Cracow, Prace Instytutu Elektrotechniki, z. 256, 2012) it was concluded that protective role against UV radiation action for plants investigated ( within the range of 315-400 nm i.e. UV-A) play flavonoids and among them e.g. flavonols and anthocyanins. They reduce UV radiation transmission through epidermis. Carotenoids, among others, belong to pigments protecting plants against harmful UV radiation for plants within UV-A radiation range and for blue range, cryptochromes and phototropins are photoreceptors. Cryptochromes show absorption maximum within the range of 390-480 nm, at vague peak at 450 nm. Photosynthetic radiation active within the PAR range (400-700 nm) is absorbed by photosynthetic pigments, mainly by chlorophyll a and b and by carotenoids. Maximum absorption for chlorophylls is within the violet- yellow range of 400-500 nm and the orange- red range 600-700 nm at absorption peaks at 420 and 668 nm for chlorophyll a and 440 and 648 nm for chlorophyll b, and for carotenoids within the range of 400-500 nm at absorption peak of appr. 420 nm, 450 nm i 480 nm. These substances impede light transmitting through greater number of plant layers. During plant fiber bleaching chemical treatment (and alternative additional acetylation), amount of chemical substances absorbing light radiation is reduced, in particular within the UV ultra-violet range, contained in plant fibers. Therefore, increased UV radiation transmission through greater number of sleeve intermediate layers containing plant fibers is obtained. Solution was shown on the drawing on which Fig. 1 shows cross section through sleeve layers.

For better explanation of solution according to invention - it was described below.

The multi-layer composite sleeve, in particular for trenchless pipeline rehabilitation, has internal film layer and alternatively, external protective layer until it is installed, intermediate mineral, organic, synthetic, alternatively non-organic fiber layers which these layers are in form of woven, quilted, felted, combed, directional fibers, alternatively loose fibers applied irregularly on preceding layers and soaked with curing resins with polymerization initiators. As internal film layer, it has elastic synthetic films with great degree of light transmittance: PE, HDPE, MDPE, PA/PE, integrated, or biodegradable films. As mineral fibers it has: glass, basalt, metal fibers. As organic fibers it has plant fibers of linen, hemp, sisal, jute, cotton, kenaf, abaca, ramia, bamboo, coconut, bagasse sugar cane, castor, soya, Attacus atlas silkworm fibers, or at least two of them, subjected to preparatory chemical treatment and alternatively to acetylation. As synthetic fibers it has propylene, Kevlar, polyester, aramid, polyethylene, terylene, viscose, polyester-aramid fibers or at least two of them. The sleeve has polymers susceptible to photo initiation by UV radiation. The sleeve has discolored plant fibers 2 in amount of 1% to 80% by weight of laminate mass, preferably pre-reinforced with synthetic plastic thin layer and/or pre-reinforced discolored plant fibers by parallel mineral or synthetic fibers 2 which it has intermediate layers I÷IV 3a, 3b, 3c, 3d with woven fabric, mat fabric, braided fabric, non-woven fabric or felt structures.

Optionally, in intermediate layers I÷IV 3a, 3b, 3c, 3d, it has variable amount of 0-100 % by volume of discolored fibers 2 relative to amount of fibers 2a, preferably polyacrylonitrile fibers, and most preferably 10-90% mineral fiber mixture. Preferably, in subsequent intermediate layers I÷IV 3a, 3b, 3c, 3d it has percentage amount of discolored fibers 2 increasing from intermediate layer I 3a with the smallest circumference to intermediate layer IV 3d with the greatest circumference, most preferably comprising basalt fibers. Preferably, in neighboring intermediate layers I÷IV 3a, 3b, 3c, 3d it has different discolored fiber 2 structure, most preferably in combination with fibers 2a. Preferably, it has discolored fibers 2 obtained from preparatory chemical treatment of known fiber bleaching. Optionally, they were subjected to acetylation process what infringed plant cell cohesion. Preferably, the sleeve has wear-resistant thin layer 10 on intermediate layer surface I 3a adjacent to external film layer 1, most preferably made of quartz sand and/or of nano-granular silica, integrated with laminate. After alternative sleeve intermediate film layer 1 destruction, thin wear- resistant layer is unveiled which still protects intermediate layers I÷IV 3a, 3b, 3c, 3d with discolored fibers 2 combined with synthetic or mineral fibers 2a with resin laminate mass against destruction.

Advantageous effects of increasing light radiation transmittance through plant fiber layers in laminate are obtained by using different methods of plant fiber bleaching.

Traditional bleaching process relies on yam mixing with bleaching agent and while maintaining it in 90 °C within 30 minutes, and bleaching agent comprises hydrogen peroxide, refining agent, penetrating agent, stabilizer, calcinated soda or caustic soda. For every 100 part of the yarn mass parts, 25 hydrogen peroxide parts, 2 parts of refining agent, 2 part of penetrating agent, 4 parts of stabilizer, 8 parts of calcinated soda or 1 part of caustic soda are required. This means that for every 100 of yarn mass parts 41 parts or 34 parts of bleaching agent. Calcinated soda may improve bleached yam whiteness up to 80% but its tenacity will be reduced to 10 cN/tex. Whereas caustic soda - conversely. Tenacity may achieve 30 cN/tex, but bleached yarn is yellow and its whiteness is only 40-50%.

From CA2068709A1 patent specification pigment removing during color removing from fibers is known. Color is removed by bleaching agents not comprising chlorine in sequence treatment with oxygen with combination with peroxide, ozone and/or hydrogensulfate in conditions of controlled pH. Acid treatment before bleaching stages improve color removing and protects fibers against damage in harder bleaching conditions. Pigment removing method from fibrous mass includes contacting this mass in first stage with gas oxygen at pH values lower than 8 or higher than 10 in which oxygen reacts with one or more pigments present in mentioned mass, thus removing mentioned pigment simultaneously forming discolored mass, provided that in the case of conducting at least one stage of initial treatment before this first stage, mentioned initial treatment is conducted at values of pH lower than 8 or higher than 10. One or more of alkaline compounds selected from group including sodium hydroxide, sodium thiosulfate, sodium sulfate, sodium carbonate, sodium hydrosulfide, ammonium hydroxide and mixtures thereof are added to this mass during contact with oxygen. Furthermore, said mass is processed in one or more stages at pH values lower than 8 or higher than 10 before said first contact stage with gas oxygen. Furthermore, hydrogen peroxide is added to said mass together with said gas oxygen in said first stage.

From CN 104631085 A patent specification bleaching process of bamboo fiber yarn in low temperature is known. Bamboo fiber has porous cross section and may quickly absorb or remove water. Bamboo fiber has low whiteness and yellow surface because of natural pigment presence. Furthermore, bamboo fiber has poor resistance to alkali and oxidation, therefore it should be bleached in conditions of low content of alkali to form white bamboo fiber. According to invention, the dyeing tank is heated till 60-80 ° C, and then, maintaining temperature to the tank bamboo fiber yarn and low-temperature bleaching agent are added. In the next stage, bamboo fiber yarn is taken out, cleansed with water and dried.

Low-temperature bleaching agent comprises following components by weight: sodium percarbonate 10-30, imidazole metal complexes 1-3, tea saponin 5-10. Imidazole complex with metal is one or bigger number, 2,4-mangan initroimidazolium, 2,4-ferrum dinitroimidazole, 2,4-copper dinitroimidazole and mangan heksaimidazole. Low-temperature bleaching agent concentration in second stage is 5-15 g / 1. Bath ratio in second stage is 1: 5-1 : 10. In second stage, maintaining time in the tank is 40-60 minutes.

In patent literature many more complicated natural fiber bleaching methods is described and some of them were discussed herein. Depending on fibers used, on the base of patent publications optimal bleaching methods for such fibers may be selected.

JPH0881878A patent specification relates to bleaching method of cellulose, wool, silk, polyamide, polyester, spandex, acrylic, or polyvinyl chloride fibers, or mixed into yarns. In this patent specification using of hydrogen peroxide, organic and non-organic hydrogen peroxide adduct which generates hydrogen peroxide in water, chlorite, hypochlorite solution and compound of following formula was disclosed

(where R is substituted or non-substituted alkyl group, allyl group or aralkyl group, and n is natural number from 1 to 6).

Alternatively, it may one or more compounds selected from group including organic peroxyacids or salts thereof or complexes represented by R1 X formula (where R1 is alkali metal or alkaline earth), X is sulfate, nitrate, acetate, maleate, fumarate, monophosphate, diphosphate, triphosphate, tripolyphosphate, hexametaphosphate ion, or pyrophosphate ion. The following bleaching agents are pointed as examples of suitable bleaching agent to be used: hydrogen peroxide, sodium bicarbonate adduct, sodium tripolyphosphate hydrogen peroxide, sodium pyrophosphate adduct, urea hydrogen peroxide adduct and the like and organic peracid represented by above formula or salt thereof (metal salt or ammonium salt). Specific examples of organic peroxy acid or salt thereof (metal salt or ammonium salt) are represented by formula include: performic acid, peracetic acid, perpropionic acid, perchloroacetic acid, pertrifluoroacetic acid, perbutylic acid and perbutylic acid, caprylic acid, perlauric acid, disuccinic acid, diperglutaric acid, diperidipic acid, monopemonanedioic acid, dipernonanedioic acid, dipemanedioic acid, monoperdecanedioic acid, diperdecanedioic acid, monoperdecanedioic acid, diperoundecanedioic acid, diphtalic acid, diperterephtalic acid, diperbenzoic acid, m- chloroperbenzoic acid, 2,4-dichloroperbenzoic acid, monopero- phthalicacid, mono monopyrcinic acid, magnesium monomorphate, monomorphic acid, monomorphate, magnesium mono monopalenoamide acid, magnesium mono monopalenoamide acid, magnesium monomorphine acid, magnesium monomorphine acid, monoformate acid, magnesium monomorphine acid, monoformate acid, magnesium, monoperglutaric acid, magnesium monoperglutaric acid, trimellitic acid, pyromellitic peracetic acid. Magnesium monoperththalate and diperidecandic acid, monoperglutaric acid, magnesium monoperglutarate, trimellitic acid, pyromellitic peracetic acid are preferred in particular. Examples of chlorine bleaching agents include: sodium chlorite and sodium hypochlorite, magnesium monoperophatalate, mono-succinic acid, magnesium monopersuccinate, monopermaleic acid, calcium monopermalate, monoperglutaric acid, magnesium monoperglutarate, trimellitic acid, pyromellitic peracetic acid. Magnesium monoperphthalate and diperidodecandic acid, monoperglutaric acid, magnesisum monoperglutarate, trimellitic acid, pyromellitic peracetic acid, are advantageous in particular.

Amount of added bleaching agent is usually 0,05 to 50% by weight in reference to bleached fiber mass. Using keywords , fiber bleaching ” in Espacenet database more than 2500 records disclosing known bleaching methods were found. However, bleaching method is not covered by independent claim of the present invention and thus only examples of possible chemical compounds using were presented. Treatment methods comprising bleaching process of hemp fibers are presented in patent specifications: CN101130885A, CN101130897A,

CN103757964A, CN103757963A, CN108823714A, CN103882679A, CN105239352A, CN107401040A, CN104562217A, CN1004288B, CN1204317C, CN103696226A,

CN101235549A, CN1844501A, CN109914124A, CN101177790A, KR101508905B1, CN100523320C and many further specifications. Treatment methods comprising bleaching process of linen fibers are presented in specifications: CN102409414A, UA41588U, CN108316014A, CN106087200A, CN101581034A, CN101100771 A, CN 107447260 A, CN102605501A, CN 109868644A, CN106835559A, CN105951235A and in many further specifications.

Disclosed solution was carried out for experimental purposes.

The composite sleeve for trenchless pipeline rehabilitation which comprised internal film layer 1 of polyamide/polyethylene PA/PE multi-layer and external protective (dark, hindering light access to uncured laminate) layer of film 5 until it is installed in repaired pipeline, while it has intermediate layers UTV 3a, 3b, 3c, 3d, shifted with longitudinal edges overlapping on neighboring intermediate layers soaked with curing resin polymerizing under influence of UV radiation. Intermediate layers 1÷IV 3a, 3b, 3c, 3d comprised linen and hemp plant fibers and were subjected to preparatory chemical treatment. In neighboring intermediate layers I÷IV 3a, 3b, 3c, 3d different amount by volume of discolored plant fibers 2 relative to mineral and synthetic fibers 2 were used. Discolored fibers 2 in amount of 1% to 80% by weight of laminate mass were utilized. In subsequent intermediate layers I÷IV 3a, 3 b, 3c, 3d percentage amount of discolored fibers (0%, 20%, 50%, 60%) increasing from intermediate layer I 3a with smallest circumference to intermediate layer IV3d with greatest circumference was used. In neighboring intermediate layers I÷IV 3a, 3b, 3c, 3d different structure of discolored fibers 2 with combination with mineral and synthetic fibers 2a was used. Discolored fibers 2 were obtained from preparatory chemical treatment of known fiber bleaching. On surface of intermediate layer I 3a in form of glass fiber woven fabric with applied non-orientated loose fibers quilted with polyacrylonitrile fiber thread, adjacent with internal film 1 layer, nano-granular silica wear-resistant thin layer 10 as sand coat bonded with viscous photocured resin was made. Further intermediate layer II 3b was made of directional mat of discolored linen fibers 2 in amount of 20%, pre-reinforced with parallel polyacrylonitrile fibers 2a through common feeding in the course of mat production, wherein for production mats in alternative strands of 50% glass fibers were also used.

Further intermediate layer III 3c was made of mat-woven fabric of acetylated and discolored linen fibers 2 in amount of 50%, pre-reinforced with PE plastic thin layer, wherein in the strands transversal to sleeve axe (circumferential) aramid fiber strands were used. Intermediate layer 3d containing 60% of discolored sisal fibers 2 with glass fibers in longitudinal mat strands and Kevlar fibers in circumferential strands on external surface possessed non-orientated basalt loose fibers linked with mat by polyethylene fiber threads.

Optionally, some layers neighboring each other among intermediate layers I÷IV 3a, 3b, 3c,

3d were stitched together before sleeve folding stage.

The layers were soaked with styrene-free resin for curing by UV radiation available for sale under the name Atlac Premium 200. At UV radiation curing, UV binders having photo- initiators are used, that is compounds which under influence of UV radiation are decomposed. Photo-initiator decomposition results in formation of radicals. They, in turn, enter into crosslinking reaction with binder forming hard polymer coating. This reaction is called photopolymerization. Optional using of resins curing in elevated temperature, e.g., utilizing hot water or steam, is possible.

Plant fibers were brought to form of discolored fibers in chemical acetylation and bleaching processes by means of methods described above, known from state-of-the art literature.

Example of sleeve implementation presented above is one of many possible to implement using different discolored plant fibers in combination with mineral or synthetic fibers used previously.

Obtained effects of using discolored plant fibers in the multi-layer sleeves soaked with resins for trenchless pipeline repairs with using disclosed solution, set new “ecological” trends and directions of research & development works for this technical field.