WO2022107831A1

WO2022107831A1 - Polyethylene fiber and method for producing same

Info

Publication number: WO2022107831A1
Application number: PCT/JP2021/042343
Authority: WO
Inventors: 史香川野; 明久古田; 靖憲福島
Original assignee: 東洋紡株式会社
Priority date: 2020-11-19
Filing date: 2021-11-17
Publication date: 2022-05-27
Also published as: JPWO2022107831A1; JP7405279B2

Abstract

The present invention provides: a polyethylene fiber which exhibits high adhesiveness without impairing characteristics intrinsic to the fiber, namely, high strength, high elastic modulus and dimensional stability at high temperatures; and a method for producing this polyethylene fiber. According to the present invention, a highly adhesive polyethylene fiber which has high fiber mechanical characteristics, especially high initial elastic modulus that contradicts adhesiveness, is achieved by applying a functional agent to a polyethylene fibrous material in a state where a residual solvent is present and by performing a heat stretching process.

Description

Polyethylene fiber and its manufacturing method

The present invention relates to a highly adhesive polyethylene fiber.

Conventionally, various techniques such as surface modification have been disclosed for improving the adhesiveness of fibers. However, since the surface of polyethylene fiber is poor in polar groups or reactive groups, it has been a big problem to obtain polyethylene fiber having adhesiveness enough to meet the market demand.
For the purpose of solving these problems, the surface of polyethylene fiber is made adhesive by various surface treatment methods such as gas flame, heated air, heating solvent, acid, fluorine treatment, corona discharge, ultraviolet rays, electron beam, radiation, plasma, etc. Attempts have been made to improve the adhesiveness. For example, Patent Document 1 discloses a method for improving the adhesiveness by forming a functional group on the fiber surface by corona treatment.

Japanese Unexamined Patent Publication No. 60-146078

The conventionally used surface treatment method such as Patent Document 1 increases the degree of treatment in order to improve the adhesiveness of the surface, and the influence extends to the inside of the fiber, so that the high strength originally possessed by the fiber is achieved. There was a problem that the high elastic modulus was impaired. Therefore, the conventional high-adhesive fiber has a lower initial elastic modulus than the untreated polyethylene fiber, and accordingly, the dimensional stability at high temperature is inferior.
Therefore, an object of the present invention is to provide a polyethylene fiber which exhibits high adhesiveness without significantly impairing the high strength, high elastic modulus and dimensional stability at high temperature originally possessed by the fiber, and a method for producing the same.

As a result of diligent research to solve the above problems, the present inventors have applied a functional agent to a polyethylene fibrous material under specific conditions, and then performed a drawing step and a heat treatment step to obtain high mechanical properties. In particular, they have found that a highly adhesive polyethylene fiber having a high initial elastic coefficient, which has a reciprocal relationship with adhesiveness, can be obtained, and completed the present invention.
Further, since these fibers have high dimensional stability at high temperature, stability in high temperature processing and high morphological retention of the molded product can be ensured.
That is, the highly adhesive polyethylene fiber according to the present invention is composed of the following technical means.
(1) A polyethylene fiber containing a single yarn made of polyethylene containing an ethylene copolymer having an epoxy ring on the side chain, and the interfacial shear strength of the single yarn for an epoxy resin produced by the microdroplet method is high. The tensile strength of the single yarn is 16 MPa or more and 30 MPa or less, the tensile strength is 20 cN / dtex or more, the initial elastic coefficient is 1000 cN / dtex or more, and the dimensional change rate of the single yarn before and after heat treatment at 140 ° C. for 30 minutes is Polyethylene fiber that is 2.5% or less.
(2) The polyethylene fiber containing 0.1% by mass or more and 1.2% by mass or less of the ethylene copolymer having an epoxy ring in the side chain.
(3) The polyethylene fiber having a single yarn fineness of 0.1 dtex or more and 80 dtex or less.
(4) A polyethylene multifilament fiber composed of three or more polyethylene fibers.
(5) An article containing the polyethylene multifilament fiber, which is either a braid, a twisted line, a fishing line, a rope, a net, a woven fabric, or a knitted fabric.
(6) A polyethylene fibrous material having an ultimate viscosity [η] of 5.0 dL / g or more and 25 dL / g or less, a repeating unit of 90 mol% or more of ethylene, and a solvent remaining of 100 ppm or more, and the above polyethylene. The above is 0 ° C. or higher and lower than 60 ° C. in a state where the polyethylene fibrous material is tensioned by using a processing liquid made of an ethylene copolymer having an epoxy ring on the side chain, which is dissolved in a soluble solvent. The processing liquid is applied to the surface of the polyethylene fibrous material, and the polyethylene fibrous material to which the processing liquid is applied is heat-treated at a temperature of 110 ° C. or higher for 10 seconds or longer to draw a total draw ratio of 30 times or less. A method for producing polyethylene fibers, which is carried out and is characterized in that the polyethylene fibrous material is unstretched or stretched at a magnification lower than the total stretch ratio.

According to the present invention, it is possible to provide a polyethylene fiber having high strength and high elastic modulus and excellent adhesiveness. Further, since this polyethylene fiber has excellent dimensional stability at high temperatures, it is suitably used as a material for braids, fishing lines, gloves, ropes, nets, woven fabrics, knits and the like.

Hereinafter, the present invention will be described in detail. The polyethylene fiber of the present invention contains at least one single yarn made of polyethylene containing an ethylene copolymer having an epoxy ring in the side chain, and the single yarn contains the interfacial shear strength, tensile strength, initial elastic modulus, which will be described later. Satisfy the dimensional change rate. All the single yarns constituting the polyethylene fiber of the present invention satisfy the interfacial shear strength, tensile strength, initial elastic modulus, and dimensional change rate described later, and contain an ethylene copolymer having an epoxy ring on the side chain. It is preferably a single yarn made of.

The interfacial shear strength of the single yarn for the epoxy resin produced by the microdroplet method is preferably 16 MPa or more and 30 MPa or less. More preferably, it is 18 MPa or more and 29 MPa or less. If the interfacial shear strength is too low, sufficient adhesiveness may not be obtained, and if the interfacial shear strength is too high, fibrillation may easily occur when shearing is applied. If the interfacial shear strength is within the above range, such a problem is unlikely to occur, which is preferable.

The tensile strength of the single yarn is preferably 20 cN / dtex or more. The tensile strength is more preferably 22 cN / dtex or more, further preferably 25 cN / dtex or more, particularly preferably 30 cN / dtex or more, and most preferably 35 cN / dtex or more. The upper limit of the tensile strength is not particularly limited, but it is technically and industrially difficult to obtain a polyethylene fiber having a tensile strength exceeding 60 cN / dtex while maintaining high adhesiveness.

The initial elastic modulus of the single yarn is preferably 1000 cN / dtex or more and 2000 cN / dtex or less. The initial elastic modulus is more preferably 1200 cN / dtex or more, further preferably 1400 cN / dtex or more, still more preferably 1900 cN / dtex or less, still more preferably 1800 cN / dtex or less. If the initial elastic modulus is too high, it becomes difficult to align the polyethylene fibers during molding into a rope or braid, and there is a risk that single yarn breakage may occur. However, if the initial elastic modulus is within the above range, It is preferable because such a problem is unlikely to occur.
The dimensional change rate of the single yarn at a high temperature (140 ° C.) is preferably 2.5% or less, more preferably 2.0% or less, still more preferably 1.5% or less. If the dimensional change rate is too high, stable machining may not be possible when heat is applied in post-machining, and mechanical properties may fluctuate.

The functional agent contained in the highly adhesive polyethylene fiber of the present invention is preferably an ethylene copolymer having an epoxy ring in the side chain. By adding an epoxy group which is a polar group, the polarity of the fiber surface is improved and the adhesiveness of the fiber tends to be improved.
The ethylene copolymer in the present invention has an ethylene unit and an epoxy group-containing monomer unit, and the epoxy group-containing monomer has, for example, an unsaturated carboxylic acid glycidyl ester having a carbonyloxy group and a methyleneoxy group. An unsaturated carboxylic acid glycidyl ether is preferred. Examples of the unsaturated carboxylic acid glycidyl ester include glycidyl acrylate, glycidyl methacrylate and itacon acid glycidyl ester, and examples of the unsaturated glycidyl ether include allyl glycidyl ether, methallyl glycidyl ether and styrene-p-glycidyl ether. And so on.
Further, the ethylene copolymer may be any of a block copolymer, a graft copolymer, a random copolymer, and an alternate copolymer.

The amount of the ethylene copolymer contained in the highly adhesive polyethylene fiber of the present invention is preferably 0.1% by mass or more and 1.2% by mass or less. The lower limit is more preferably 0.3% by mass or more, and further preferably 0.5% by mass or more. The upper limit is more preferably 1.0% by mass or less, still more preferably 0.8% by mass or less. If the amount of the ethylene copolymer introduced is too small, high adhesiveness may not be exhibited, and if the amount introduced is too large, the mechanical properties of the fiber may be affected.

The fineness of the single yarn is preferably 0.1 dtex or more and 80 dtex or less. If the single yarn fineness exceeds 80 dtex, the polyethylene fiber may become hard and at the same time it may be difficult to increase the strength. It is preferably 70 dtex or less, more preferably 60 dtex or less, preferably 0.7 dtex or more, and more preferably 1 dtex or more. Fibers of less than 0.7 dtex may easily generate fluff or the like during stretching in the manufacturing process or when polyethylene fibers are actually used.

The breaking elongation of the single yarn is preferably 2.0 to 7.0%, more preferably 3.0 to 5.0%. If the elongation at break is lower than 2.0%, when multiple multifilaments are aligned and processed into a rope, the alignment of each multifilament becomes poor, and productivity decreases due to troubles such as single yarn breakage. There is a risk that the strength of the rope will be reduced. Further, when the elongation at break is larger than 7.0%, it is technically and industrially difficult to obtain a polyethylene fiber having a tensile strength within the above range.

The number of single yarns constituting the polyethylene multifilament fiber is preferably 3 or more. If the number of composed single yarns is less than 3, the fibers may become hard and difficult to handle in actual use. Further, the polyethylene multifilament fiber is preferably composed of three or more polyethylene fibers of the present invention.

The initial elastic modulus of the highly adhesive polyethylene multifilament fiber of the present invention is preferably 950 cN / dtex or more and 1900 cN / dtex or less. The initial elastic modulus is more preferably 1000 cN / dtex or more, further preferably 1100 cN / dtex or more, particularly preferably 1200 cN / dtex or more, still more preferably 1800 cN / dtex or less, still more preferably 1600 cN. It is less than / dtex. If the initial elastic modulus is too high, it becomes difficult to align the polyethylene fibers during molding into a rope or braid, and there is a risk that single yarn breakage may occur. However, if the initial elastic modulus is within the above range, It is preferable because such a problem is unlikely to occur.

In the present invention, the above-mentioned functional agent contributing to high adhesiveness is strongly present on the surface layer of the single yarn, so that the adhesiveness, that is, the interfacial shear strength in the pull-out test is improved, and polyethylene having an ultra-high molecular weight is used. It is presumed that high strength and high elastic modulus are achieved by being present in the center of the single yarn. When the functional agent is uniformly dispersed in the single yarn, the present inventors do not have the effect of the present invention, and the ratio of the functional agent on the surface of the single yarn is higher than that in the center of the single yarn. It was found that high strength, high elastic modulus and high adhesiveness can be achieved only when they are present in. In order to allow the functional agent to be present in a higher proportion on the surface of the single yarn than in the center of the single yarn, it may be produced by the following production method.

With the current analytical equipment, it is difficult to confirm the distribution of the functional agent in the fiber, which is present in a trace amount. It shows that it exists strongly.

The manufacturing method according to the present invention is shown below.

In the present invention, a highly adhesive polyethylene fiber is produced by a solution forming method. As the solution forming method, a conventionally known method may be adopted and is not particularly limited. For example, polyethylene is dissolved in a volatile organic solvent such as decalin or tetraline or a non-volatile organic solvent such as paraffin to form polyethylene. It is preferable to adopt a solution spinning method in which polyethylene is formed into a fibrous form.

As the raw material polyethylene for the polyethylene fiber of the present invention, it is preferable to use polyethylene having an ultimate viscosity [η] of 5.0 dL / g or more and 25 dL / g or less, and 90 mol% or more of the repeating unit is ethylene. The ultimate viscosity is more preferably 7.0 to 22 dL / g, still more preferably 8.0 to 20 dL / g. If the ultimate viscosity is too small, the dimensional stability is inferior, the fluctuation of the mechanical characteristics with time tends to be large, and it may be difficult to realize the tensile strength of 20 cN / dtex or more. On the other hand, if the ultimate viscosity is too large, high strength and high elastic modulus can be easily realized, but there is a risk that single yarn breakage will occur frequently in the post-process of processing polyethylene fibers into products such as braids. By using polyethylene having an ultimate viscosity within the above range as a raw material, the molecular terminal groups of polyethylene are in an appropriate range, and the number of structural defects in fibers and textile products can be reduced. As a result, mechanical properties such as tensile strength and initial elastic modulus of polyethylene fiber, dimensional stability, and abrasion resistance can be improved, and fluctuations in mechanical properties over time can be suppressed.

The raw material polyethylene is ethylene in 90 mol% or more of the repeating unit. The repeating unit of ethylene is preferably 92 mol% or more, more preferably 94 mol% or more, and most preferably a homopolymer of ethylene. The raw material polyethylene may contain a component other than ethylene as long as it does not adversely affect the physical properties of the polyethylene fiber. For example, polyethylene as a raw material is a copolymer of ethylene and a small amount of other monomers, specifically α-olefin, acrylic acid and its derivative, methacrylic acid and its derivative, vinylsilane and its derivative, and other monomers and ethylene. Can be used as. In the following, polyethylene having an intrinsic viscosity [η] of 5.0 dL / g or more and 25 dL / g or less and 90 mol% or more of repeating units being ethylene is referred to as ultra-high molecular weight polyethylene.

Further, if the ultimate viscosity is within the above range, the raw material polyethylene includes, for example, a blend of high-density polyethylene and ultra-high molecular weight polyethylene, and a blend of low-density polyethylene and ultra-high molecular weight polyethylene, and polyethylene having different weight average molecular weights. May be a blend of. Further, the raw material polyethylene may be a blend of two or more types of ultra-high molecular weight polyethylene having different weight average molecular weights, or may be a blend of two or more types of ultra-high molecular weight polyethylene having different molecular weight distributions.

However, if the content of components other than ethylene increases too much, it may rather hinder stretching. Therefore, from the viewpoint of obtaining high-strength fibers, the number of branches existing in polyethylene is preferably 3 or less per 1000 main chain carbon atoms. It is more preferably 2 or less, still more preferably 1.5 or less. Regarding the number of branches, 250 mg of the sample was dissolved in a solvent in which o-dichlorobenzene: p-dichlorobenzene-d ₄ was mixed so as to have a volume ratio of 7: 3 at 145 ° C., and then ¹³ C- at 120 ° C. NMR can be measured and calculated from the obtained ¹³ C-NMR spectrum by the following method.
When the ethylene chain peak of polyethylene is 30 ppm, the peak derived from the methyl side chain is detected at around 37.5 ppm, the peak derived from the ethyl side chain is detected at around 34 ppm, and the peak derived from the butyl side chain is detected at around 23.5 ppm. .. When the integral value of the ethylene chain peak is 1000, the peak integral value of 37.5 ppm is A, the peak integral value of 34 ppm is B, and the peak integral value of 23.5 ppm is C, the number of methyl side chains is A /. It can be calculated as 2 (pieces / 1000C), the number of ethyl side chains is B / 2 (pieces / 1000C), and the number of butyl side chains is C / 2 (pieces / 1000C).

Prepare a polyethylene solution by dissolving the above-mentioned raw material polyethylene in an organic solvent. The concentration of polyethylene is 0.5% by mass or more and 40% by mass or less, preferably 2.0% by mass or more and 30% by mass or less, and more preferably 4.0% by mass or more and 20% by mass or less. If the polyethylene concentration is too low, the production efficiency tends to decrease. On the other hand, if the concentration of polyethylene is too high, it tends to be difficult to discharge from a nozzle, which will be described later, in the solution spinning method due to the extremely large molecular weight of the raw material polyethylene.

As the organic solvent for dissolving the raw material polyethylene, an organic solvent that can dissolve the raw material polyethylene and has a boiling point higher than the melting point of the raw material polyethylene is preferable, and an organic solvent having a boiling point 20 ° C. or higher higher than the melting point of the raw material polyethylene is preferable. More preferred. Examples of such a solvent include n-nonane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane, or aliphatic hydrocarbon solvents such as liquid paraffin and kerosene, xylene, naphthalene (naphthalene), and the like. Aromatic hydrocarbon solvents such as tetraline (tetrahydronaphthalene), decalin (decahydronaphthalene), butylbenzene, p-simene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, methylnaphthalene, ethylnaphthalene or their hydrogens. Halogened hydrocarbon solvents such as chemical derivatives, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene, 1,2,4-trichlorobenzene, bromobenzene, etc. , Paraffin-based process oil, naphthalene-based process oil, aromatic process oil and other mineral oils. Among these organic solvents, a volatile organic solvent is preferable because it can remove the organic solvent from the polyethylene fibrous material at the same time as stretching in the stretching step described later. In addition, in this specification, "polyethylene fibrous material" refers to unstretched or stretched at a magnification less than the total draw ratio described later, that is, unstretched yarn or stretched at a magnification less than the total draw ratio described later. It means a drawn yarn (hereinafter referred to as an intermediate yarn). Specifically, the intermediate yarn refers to a drawn yarn in which at least one step of drawing is not performed when the drawing step is multi-step drawing of two or more steps.

The polyethylene solution is preferably heated at a temperature 10 ° C. or higher higher than the melting point of the raw material polyethylene (melting point of the raw material polyethylene + 10 ° C. or higher) and then passed through a spinning nozzle (spinning cap) to obtain undrawn yarn (spinning step). ). The heating temperature is more preferably + 20 ° C. or higher, which is the melting point of the raw material polyethylene, and more preferably + 30 ° C. or higher, which is the melting point of the raw material polyethylene. By heating within the above temperature range, the raw material polyethylene dispersed in the organic solvent can be dissolved to obtain a uniform solution.

The temperature of the spinneret is preferably such that the melting point of the raw material polyethylene is + 5 ° C. or higher and the boiling point of the organic solvent used in the polyethylene solution or lower. More preferably, the melting point of the raw material polyethylene is + 10 ° C. or higher. If the temperature of the spinneret is too low, the viscosity of the raw material polyethylene may decrease, making it difficult to take up the undrawn yarn at a desired speed. On the other hand, when the temperature of the spinneret exceeds the boiling point of the organic solvent, the organic solvent boils immediately after the polyethylene solution is discharged from the spinneret, and there is a possibility that yarn breakage occurs frequently directly under the spinneret.

The molded product discharged from the spinning nozzle is cooled and solidified, and then taken back to obtain undrawn yarn. The cooling method is not particularly limited, and the molded product discharged from the spinneret may be naturally cooled by exposing it to the atmospheric temperature, or a cooling device may be used. The cooling method using the cooling device may be a dry quenching method using a gas such as air or nitrogen, or a liquid that can be mixed with the organic solvent used in the polyethylene solution, or a liquid such as water that is mixed with the organic solvent used in the polyethylene solution. A cooling method using a difficult liquid may be used.

It is preferable that the discharged molded product is deformed at a magnification of 1.1 times or more and 100 times or less until it is cooled and solidified to become an undrawn yarn. The deformation ratio is more preferably 2.0 times or more and 80 times or less, further preferably 5.0 times or more and 50 times or less, and particularly preferably 7.0 to 30 times. The time required for deformation is preferably 3 minutes or less. It is more preferably within 2 minutes, and even more preferably within 1 minute. If the time required for deformation exceeds 3 minutes, the polyethylene molecular chains constituting the undrawn yarn may be relaxed, making it difficult to obtain polyethylene fibers having high strength and high elastic modulus. In the step of spinning the polyethylene solution to obtain the undrawn yarn, a part of the solvent contained in the undrawn yarn may be removed.

Next, the obtained undrawn yarn is heated and drawn (drawing step). The stretching step may be one-step stretching or multi-step stretching of two or more steps. From the viewpoint of increasing the strength of the polyethylene fiber, it is preferable to perform multi-stage stretching in two or more stages. The total draw ratio is preferably 8 times or more, more preferably 10 times or more, still more preferably 12 times or more. The upper limit of the total draw ratio is preferably 30 times or less, more preferably 25 times or less, and further preferably 20 times or less. The total draw ratio is a value obtained by dividing the length of the polyethylene fiber that has been stretched in the final stage by the length of the undrawn yarn.

The method for heating the polyethylene fibrous material (unstretched yarn and intermediate yarn) in the drawing step is not particularly limited, and may be heated using a medium such as air, an inert gas such as nitrogen, steam, or a liquid. Further, a heating roller, a contact heater, or the like may be used. The stretching temperature is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and even more preferably 130 ° C. or higher. The upper limit of the stretching temperature may be a range in which the fibers do not melt.
The draw ratio of the polyethylene fiber is preferably 8 times or more, more preferably 10 times or more, still more preferably 12 times or more as the total draw ratio on the roller. The upper limit of the draw ratio is not particularly limited as long as it is 30 times or less, and it may be determined so that a polyethylene fiber having a desired tensile strength, elongation at break and initial elastic modulus can be obtained.

When the polyethylene solution contains a volatile organic solvent, the organic solvent contained in the fibrous material can be removed at the same time as the polyethylene fibrous material is stretched (desolvent). On the other hand, when the organic solvent constituting the polyethylene solution is non-volatile, the non-volatile organic solvent may be removed from the polyethylene fibrous material by extraction. For extraction, for example, organic solvents such as chloroform, benzene, trichlorotrifluoroethane (TCTFE), hexane, heptane, nonane, decane, ethanol and higher alcohols can be used.
The desolvation step of removing the organic solvent from the polyethylene fibrous material may be carried out as a step different from the stretching step, or may be carried out at the same time as the stretching step.

The manufacturing method of the present invention includes, in addition to the above-mentioned spinning step and drawing step, a step of bringing the polyethylene fibrous material into contact with the processing liquid (processing liquid contact step). In the processing liquid contacting step, a polyethylene fibrous material containing an organic solvent of 100 ppm or more is brought into contact with a working liquid containing a functional agent and an organic solvent and having a temperature of 0 ° C. or higher and lower than 60 ° C. under tension. This makes it possible to impart a functional agent to the polyethylene fibrous material.

The timing of the processing liquid contacting step is not limited as long as it is performed on a polyethylene fibrous material having an organic solvent amount of 100 ppm or more. However, after the polyethylene crystallization is completed, it may be difficult to move the functional agent to the inside of the fibrous material, so this is carried out before the final drawing step of stretching the polyethylene fibrous material to a preset draw ratio. Is preferable. Therefore, the processing liquid contacting step is preferably performed after the spinning step and before the drawing step, and when performing multi-step stretching of two or more steps, it is performed during the drawing step, for example, in the case of two-step stretching, the first step and the second step. It may be performed during the stitch stretching step.

The amount of the organic solvent (residual solvent amount) contained in the polyethylene fibrous material is 100 ppm or more, preferably 200 ppm or more, preferably 20% by mass or less, more preferably 15% by mass or more, still more preferable. Is 10% by mass or more, particularly preferably 5% by mass or less, and most preferably 2% by mass or less. Before the solvent is completely removed, it is easy to move the functional agent to the inside of the polyethylene fibrous material, so that it is considered that the functional agent can be present inside the individual fibrous material. Therefore, from the viewpoint of fixing the functional agent to the inside of the fiber, it is preferable to perform the processing liquid contact step in a state where the polyethylene fibrous material contains a residual solvent to some extent. However, if the amount of residual solvent is too large or too small, the movement of the functional agent into the fibrous material tends to be hindered. If the amount of residual solvent is too large, it is recommended to perform the above-mentioned desolvation in the processing liquid contacting step to keep the amount of residual solvent within the above range.

As the functional agent, the above-mentioned one is preferably used. More preferably, it is an ethylene / glycidyl methacrylate copolymer. The concentration of the functional agent in the processing liquid may be adjusted so that the highly adhesive polyethylene fiber contains 0.1 to 1.2% by mass of the functional agent, but in general, the functional agent in the processing liquid is used. The concentration of is preferably 1% by mass to 5% by mass. It is more preferably 1.2% by mass or more and 4% by mass or less, and further preferably 1.4% by mass or more and 3% by mass or less. If the concentration of the functional agent is too low, it may be difficult to develop sufficient adhesiveness, and if the concentration of the functional agent is too high, the excess functional agent remains on the fiber surface, and the adhesiveness of the polyethylene fiber is lowered. It is not preferable because it may cause a problem.

The temperature of the working liquid is 0 ° C. or higher and lower than 60 ° C. It is more preferably 5 ° C. or higher, further preferably 8 ° C. or higher, even more preferably 10 ° C. or higher, preferably 50 ° C. or lower, and even more preferably 40 ° C. or lower.
The temperature of the polyethylene fibrous material to be brought into contact with the processing liquid is preferably 50 ° C. or lower, more preferably 45 ° C. or lower, and further preferably 40 ° C. or lower. There is no limit to the lower limit of the temperature of the polyethylene fibrous material, but it is generally preferable that the temperature is above room temperature. The temperature of the polyethylene fibrous material can be measured by, for example, a non-contact type thermometer such as an infrared thermometer.

If the temperature of the processing liquid is too high, when a volatile organic solvent is used, the organic solvent evaporates quickly and only the functional agent remains on the surface of the polyethylene fibrous material and functions even inside the polyethylene fibrous material. It tends to be difficult to move the agent. In this case, there is a risk of contaminating peripheral members in the subsequent steps. If the temperature of the working liquid is too high, the temperature of the polyethylene fibrous material in contact with the working liquid will rise, and the tension applied to the polyethylene fibrous material in the heat treatment step and stretching step performed after the working liquid contacting step will have an effect. As a result, there is a possibility that fineness unevenness and strength unevenness (thread unevenness) may occur. In particular, when the drawing step is performed after the working liquid contacting step, if the temperature of the polyethylene fibrous material is too high, the drawing point is not fixed and there is a possibility that stretching unevenness may occur.
Even if the temperature of the polyethylene fibrous material is sufficiently low, if the temperature of the processing liquid is high, the crystal structure formed in the polyethylene fibrous material collapses at the time of contact with the processing liquid, resulting in uneven application. May occur. When the temperature of the processing liquid and the temperature of the polyethylene fibrous material are within the above ranges, the above-mentioned problems are unlikely to occur, which is preferable.

The contact method between the polyethylene fibrous material and the processing liquid is not particularly limited as long as the processing liquid can be applied to the polyethylene fibrous material, and various methods can be used. Specific contact methods include a method of contacting the polyethylene fibrous material with the processing liquid by guide oiling, a method of contacting the polyethylene fibrous material with the surface of the rotating roller to which the processing liquid is adhered, and a running polyethylene fibrous material. Examples thereof include a method of spraying a processing liquid on an object, a method of passing a polyethylene fibrous material through a bath of the processing liquid and bringing it into contact with the object. When the polyethylene solution contains a non-volatile organic solvent (for example, paraffin), a processing solution in which a functional agent is dissolved in an extraction solvent used in the desolvation step is used as an extraction bath, and polyethylene fibers are contained in this extraction bath. The polyethylene fibrous material and the processing liquid may be brought into contact with each other by passing the material through the material.

The amount of the processing liquid applied to the polyethylene fibrous material is preferably in the range of 10 to 60% by mass with respect to the polyethylene fibrous material. It is more preferably 15% by mass or more, further preferably 20% by mass or more, still more preferably 58% by mass or less, still more preferably 55% by mass or less. If the amount of the processing liquid applied is too small, it may be difficult to develop sufficient adhesiveness, while if the amount of the processing liquid applied is too large, an excess functional agent remains on the fiber surface and the adhesiveness of the polyethylene fiber becomes poor. There is a risk of deterioration.

The processing liquid contacting step is preferably carried out while applying a tension of 0.05 cN / dtex or more and 3 cN / dtex or less to the polyethylene fibrous material. It is more preferably 0.1 cN / dtex or more and 1 cN / dtex or less, and further preferably 0.2 cN / dtex or more and 0.8 cN / dtex or less. If the tension applied to the polyethylene fibrous material is too small, it is difficult to allow the polyethylene fibrous material to run stably, runout may occur, and unevenness of the functional agent may occur. On the other hand, if the tension is too large, the polyethylene fibrous material may be in a converged state and it may be difficult for the processing liquid to permeate into the inside of each fibrous material. In this case, not only the unevenness of applying the functional agent for each single yarn becomes large, but also most of the functional agent remains on the surface of the polyethylene fiber-like material, and as a result, the adhesiveness of the polyethylene fiber may decrease.

The period from the processing liquid contacting step to the heat treatment step is preferably 10 seconds or more and 100 seconds or less, and more preferably 20 seconds or more and 90 seconds or less. If the time until the heat treatment step is too long, the solvent applied to the polyethylene fibrous material may volatilize, making it difficult for the functional agent to move to the deep part of the polyethylene fibrous material. On the other hand, if the time until the heat treatment step is too short, the permeation of the functional agent into the polyethylene fibrous material may not proceed sufficiently, which is not preferable.

In the present invention, a heat treatment step of heating the polyethylene fibrous material to which the processing liquid is applied at 110 ° C. or higher for 10 seconds or longer is carried out (heat treatment step). As a result, the permeation of the processing liquid into the polyethylene fibrous material is promoted, and it becomes easy to move the functional agent to the deep part of the polyethylene fibrous material. As a result, a polyethylene fiber exhibiting high adhesiveness can be obtained. By performing the heat treatment step, the stretching step is carried out in a state where the functional agent is present inside the polyethylene fibrous material, and the functional agent can be confined inside the polyethylene fiber by crystallization of polyethylene by stretching. It is thought that this is because it can be done.

The heat treatment step may be performed at any timing after the working liquid contact step. Further, the heat treatment step may be performed alone or at the same time as the stretching step. When the heat treatment step is performed at the same time as the stretching step, the movement of the functional agent into the polyethylene fibrous material due to the permeation of the processing liquid and the crystallization of polyethylene due to the stretching can proceed at the same time. Further, when the heat treatment step and the stretching step are performed separately, the stretching step can be performed after the functional agent is moved to the inside of the polyethylene fiber by the heat treatment step, so that the functional agent is confined inside the polyethylene fiber. be able to. Preferably, the heat treatment step is performed at the same time as the stretching step.

The heating temperature is preferably 120 ° C. or higher, more preferably 130 ° C. or higher. It is recommended that the upper limit of the heating temperature be a temperature at which thread breakage does not occur due to fusing, that is, a temperature equal to or lower than the melting point of the polyethylene fibrous material.

There are no particular restrictions on the heating method, and known methods such as hot air, hot rollers, radiant panels, steam jets, and hot pins can be adopted. From the viewpoint of minimizing contamination by the functional agent, it is preferable to adopt a non-contact type heating method using hot air, a radiant panel, a steam jet, or the like.

The heating time is preferably 10 seconds or longer, more preferably 12 seconds or longer, and even more preferably 15 seconds or longer. The upper limit of the heating time is not particularly limited, but is preferably 150 seconds or less, more preferably 120 seconds or less, and further preferably 100 seconds or less. When the heat treatment step is carried out independently, it is preferable to carry out the heat treatment step and the stretching step within the above range.

It is preferable that the heat treatment step is performed while applying tension to the polyethylene fibrous material. The tension applied to the polyethylene fibrous material is preferably 0.8 cN / dtex to 6.5 cN / dtex. It is more preferably 1 cN / dtex or more, further preferably 2 cN / dtex or more, more preferably 6 cN / dtex or less, still more preferably 5 cN / dtex or less.

It is preferable because the capillarity occurs by stretching the molecular chain of polyethylene by applying the tension in the above range in the heat treatment step, and the permeation of the processing liquid into the polyethylene fibrous material is further promoted. If the tension in the heat treatment step is too small, the capillary phenomenon may be less likely to occur. On the other hand, if the tension is too high, fluffing or the like may occur, and it may be difficult to obtain polyethylene fibers having less unevenness in fineness and strength.

In the stretching step performed after the heat treatment step or at the same time as the heat treatment step, it is preferable to stretch the polyethylene fibrous material at a magnification of at least 2 times. More preferably, it is 2.5 times or more. As the upper limit, it is preferable to increase the draw ratio as much as possible for the purpose of increasing the strength, but if it is too high, thread breakage and fluffing may be observed. Therefore, the draw ratio is preferably 30 times or less, more preferably 10 times or less, and further preferably 5 times or less.
Usually, in the production of polyethylene fiber, stretching is performed at a high drawing ratio in order to increase the strength of the fiber. However, if it is brought into contact with a processing liquid having a relatively high temperature before the stretching step, the polyethylene fibrous material softens at the stage of being subjected to the stretching step. May not be fixed and may cause unevenness in fineness and strength. Therefore, it is preferable that the stretching ratio in the stretching step performed after the heat treatment step or at the same time as the heat treatment step is within the above range.

The highly adhesive polyethylene fiber and polyethylene multifilament fiber of the present invention exhibit high adhesiveness without deteriorating the mechanical properties of tensile strength and initial elastic coefficient. Therefore, braids, fishing threads, gloves, ropes, nets, and woven fabrics And is suitably used as a material for knitted fabrics and the like. All the threads used for these applications may be the above-mentioned high-adhesive polyethylene fibers, or some of them may be high-adhesive polyethylene fibers. For example, in the case of braid, it is desirable that it contains at least one highly adhesive polyethylene fiber of the present invention.
The braid preferably has a tensile strength of 15 cN / dtex or more of the single yarn (polyethylene fiber) unwound from the braid. It is more preferably 18 cN / dtex or more, and even more preferably 20 cN / dtex or more. The upper limit of the tensile strength is the same as that of the above-mentioned highly adhesive polyethylene fiber.

This application claims the benefit of priority based on Japanese Patent Application No. 2020-192764 filed on November 19, 2020. The entire contents of the specification of Japanese Patent Application No. 2020-192764 filed on November 19, 2020 are incorporated herein by reference.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples as well as the present invention, and appropriate modifications are made to the extent that it can meet the purposes of the preceding and the following. Of course, it is possible to carry out, and all of them are included in the technical scope of the present invention.

(1) Measurement of interfacial shear strength by microdroplet method Epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., jER827, bisphenol A type epoxy resin, hue (Gardner) 0.6max, viscosity 90-110P / 25 ° C., epoxy equivalent 180 ~ 190, specific gravity 1.16), curing agent A (HN-5500 manufactured by Hitachi Chemical Co., Ltd., 3or4-methyl-hexahydrohydroan phthalic acid), curing agent B (Mitsubishi Chemical Co., Ltd., IBMI12, 1-isobutyl-2-methyl) (Imidazole) was mixed at a weight ratio of epoxy resin: curing agent A: curing agent B = 100: 85: 1 and pre-cured at 25 ° C. for 24 hours to prepare a resin.
After fixing both ends of a single yarn of a certain length to a holder that can move in the horizontal direction, the above-mentioned pre-cured resin in a molten state is brought close to the single yarn, and the pre-cured resin is attached to the single yarn. To form microdroplets. Then, the resin was cured under the conditions of 100 ° C. for 2 hours to prepare a sample. The above was repeated multiple times to create samples with various sizes of microdroplets.
The above sample was subjected to a fiber drawing test using a composite material interface characteristic evaluation device MODELHM410 manufactured by Toei Sangyo Co., Ltd. In the sample in which the microdroplet is created on the single yarn, a blade that prevents the movement of the microdroplet is arranged, and the single yarn is pulled out from the microdroplet while the microdroplet does not move with the blade. It was moved and the maximum withdrawal load acting during this movement was measured. At this time, the fiber pulling speed was set to 0.3 mm / min.
The interfacial shear strength was obtained from the obtained maximum pull-out load using the following formula 1, and the average value of the results of the number of tests n = 50 was taken as the measured value.
Interfacial shear strength (MPa) = drawing load (N) / (fiber diameter (mm) x resin ball length (fiber axial direction) (mm) x pi) (Equation 1)

(2) Tensile strength, elongation at break, initial elastic modulus Measured according to JIS L1013 8.5.1. For the tensile strength and initial elastic modulus of single yarn and multifilament, the sample length 200 mm (chuck length), elongation speed 100 mm / min, atmospheric temperature using "Tencilon universal material tester" manufactured by Orientec Co., Ltd. The strain-stress curve is measured under the conditions of 20 ° C. and relative humidity of 65%, and the tensile strength (cN / dtex), breaking elongation (%), and maximum gradient near the origin of the curve are determined from the stress and elongation at the breaking point. The initial elastic modulus (cN / dtex) was calculated and obtained from the given tangent line. At this time, the initial load applied to the sample at the time of measurement was set to 1/10 (cN / dtex) of the fineness. For each value, the average value of the measured values of 7 times was used.

(3) Thread fineness and dimensional change rate A sample of 10 m each was sampled, and the weight thereof was measured to determine the thread fineness (dtex). The single yarn fineness can be calculated by dividing the fineness of the yarn by the number of constituents of the multifilament.
The dimensional change rate was measured by the following method. A single yarn of polyethylene fiber was taken out by 50 cm and placed in an incubator at 140 ° C. with no load so that the fiber was vertical. After 30 minutes, the samples were taken out, their lengths were measured, and the dimensional change rate was determined using the following formula 2. For each value, the average value of the two measured values was used.
Dimensional change rate (%) = (fiber length before heat treatment-fiber length after heat treatment) / fiber length before heat treatment x 100 (Equation 2)

(4) Amount of functional agent introduced in the fiber The functional agent was quantified by ¹ H-NMR measurement at a resonance frequency of 600 MHz. As a measuring device, an NMR device AVANCE-NEO600 manufactured by BRUKER was used, and the measurement was performed as follows.
An NMR tube was filled with 10 to 15 mg of a sample, heavy tetrachloroethane to which a known amount of dimethylisophthalate was added was added, and the mixture was dissolved at 110 ° C. and then measured. Heavy tetrachloroethane was used as the lock solvent, the waiting time was 1 second, the data acquisition time was 4 seconds, the number of integrations was 128 times, and the measurement temperature was 110 ° C. The modifier weight can be calculated from the integral value ratio of the modifier-derived peak and dimethylisophthalate, and the modifier amount (wt% vs. sample) can be quantified from the sample amount and its ratio.

(5) Extreme Viscosity The specific viscosity of various dilute solutions is measured with a Ubbelohde-type capillary viscosity tube at 135 ° C., and the extrapolation point to the origin of the straight line obtained by the minimum square approximation of the plot to the concentration of the viscosity. The more extreme viscosity was determined.

(Example 1)
The dispersion of ultra-high molecular weight polyethylene and decahydronaphthalene having an ultimate viscosity of 18.8 dL / g was adjusted to a polyethylene concentration of 10.5% by mass. This dispersion is heated at 200 ° C. with an extruder to make a solution, and the polyethylene solution is discharged from a spinneret having an orifice diameter of φ0.6 mm at a nozzle surface temperature of 180 ° C. so that the number of single threads is 192. Discharged at 6 g / min. Nitrogen gas was dried so as to hit the yarn as evenly as possible directly under the nozzle, and the discharged material was deformed 10 times at a speed of 110 m / min to obtain an undrawn yarn. Subsequently, the undrawn yarn was drawn with hot air of nitrogen at 100 ° C., and further continuously drawn with hot air at 140 ° C. to obtain a quadruple stretched intermediate yarn. After combining the four obtained intermediate yarns, a processing solution prepared by dissolving 4% by mass of an ethylene / glycidyl methacrylate copolymer (Flobeads GM-40400, manufactured by Sumitomo Seika Chemical Co., Ltd.) in decahydronaphthalline as a functional agent was prepared. The yarn was applied, and after 50 seconds had passed from the application, the yarn was stretched 3.5 times at 150 ° C. and wound to perform a stretching step and a heat treatment step at the same time. At this time, the amount of the functional agent applied to the intermediate yarn was adjusted to 2% by mass. The stretching step and the heat treatment step were performed for 80 seconds. Table 1 shows the processing liquid temperature, the amount of the processing liquid applied to the intermediate yarn, the tension at the time of application, and the tension at the time of the heat treatment step.
In the measurement of the interfacial shear strength, 50 resin balls having a size of 68 μm to 154 μm were arbitrarily selected and a drawing test was carried out.
Various physical properties are as shown in Table 1. The details of the analysis of the amount of the functional agent introduced are shown below. ¹ From 1 H-NMR measurement, when the tetrachloroethane peak is 6 ppm, the functional agent-derived glycidyl peak is detected at 2.4 to 3 ppm, and the dimethylisophthalate-derived peak is detected at 3.8 ppm.
When the original sample amount is A (mg), the amount of dimethylisophthalate added is B (mg), the integral value of glycidyl peak at 2.4 ppm is C, and the integral value of dimethylisophthalate peak at 3.8 ppm is D, the amount of functional agent. Can be expressed by the following equation 3.
Amount of functional agent (wt% vs. sample) = (846.2 x C x B ÷ 32.3 ÷ D) x 100 ÷ A (Equation 3)

(Example 2)
Polyethylene multifilament fibers were spun and drawn under the same conditions as in Example 1 except that the concentration of the processing liquid used in Example 1 was changed to 2% by mass and the tension was set to 3.0 cN / dtex. Manufactured. The manufacturing conditions and various physical properties are as shown in Table 1.
Since the amount of the functional agent introduced into the fiber is below the detection limit of NMR, the results of the samples prepared under the same conditions including Example 1 are used to compare the above-mentioned Example 1 with the following. Calculated from extrapolated lines from the results of Example 2.

(Comparative Example 1)
Polyethylene multifilament fibers were produced by spinning and drawing under the same conditions as in Example 1 except that the undrawn yarn and the processing liquid were not brought into contact with each other. The manufacturing conditions and various physical properties are as shown in Table 1.

(Comparative Example 2)
Polyethylene multifilament fibers were produced by spinning and drawing under the same conditions as in Example 2 except that the concentration of the processing liquid used in Example 2 was changed to 6% by mass. The manufacturing conditions and various physical properties are as shown in Table 1.

(Comparative Example 3)
A functional agent-imparting fiber was produced by immersing the same functional agent processing liquid as in Example 2 in the polyethylene multifilament fiber produced under the conditions of Comparative Example 1 and drying it. The manufacturing conditions and various physical properties are as shown in Table 1.

(Comparative Example 4)
A dispersion prepared by adding 1% by mass of an ethylene / glycidyl methacrylate copolymer as a functional agent to a dispersion of ultra-high molecular weight polyethylene and decahydronaphthalene was mixed in advance with a deformation ratio of 7 times. Except for this, polyethylene multifilament fiber was produced by spinning and drawing under the same conditions as in Comparative Example 1. The manufacturing conditions and various physical properties are as shown in Table 1.

(Comparative Example 5)
The polyethylene multifilament fibers produced under the conditions of Comparative Example 1 were subjected to corona treatment. The processing was performed using a corona processing machine manufactured by Kasuga Denki Co., Ltd. under the conditions of an output of 900 W, a processing speed of 90 m / min, and a processing time of 15 seconds. The manufacturing conditions and various physical properties are as shown in Table 1.

According to the present invention, it is possible to provide a polyethylene fiber having high strength and high elastic modulus and excellent adhesiveness. Further, since the polyethylene fiber is excellent in dimensional stability at high temperature, the multifilament made of the polyethylene fiber is suitably used as a material for braids, fishing threads, gloves, ropes, nets, woven fabrics, knitted fabrics and the like.

Claims

A polyethylene fiber containing a single yarn made of polyethylene containing an ethylene copolymer having an epoxy ring in the side chain.
The interfacial shear strength of the single yarn of the epoxy resin produced by the microdroplet method is 16 MPa or more and 30 MPa or less.
The single yarn has a tensile strength of 20 cN / dtex or more and an initial elastic modulus of 1000 cN / dtex or more.
A polyethylene fiber having a dimensional change rate of 2.5% or less of the single yarn before and after heat treatment at 140 ° C. for 30 minutes.
The polyethylene fiber according to claim 1, which contains 0.1% by mass or more and 1.2% by mass or less of the ethylene copolymer having an epoxy ring in the side chain.
The polyethylene fiber according to claim 1 or 2, wherein the single yarn has a fineness of 0.1 dtex or more and 80 dtex or less.
A polyethylene multifilament fiber comprising 3 or more polyethylene fibers according to any one of claims 1 to 3.
An article that is either a braid, a twisted line, a fishing line, a rope, a net, a woven fabric, or a knit, containing the polyethylene multifilament fiber according to claim 4.
A polyethylene fibrous material having an ultimate viscosity [η] of 5.0 dL / g or more and 25 dL / g or less, a repeating unit of 90 mol% or more of ethylene, and a solvent remaining of 100 ppm or more.
Using a processing solution made of an ethylene copolymer having an epoxy ring on the side chain, which was dissolved in a solvent in which polyethylene was soluble, was used.
With tension applied to the polyethylene fibrous material, the processing liquid having a temperature of 0 ° C. or higher and lower than 60 ° C. is applied to the surface of the polyethylene fibrous material.
The polyethylene fibrous material to which the above processing liquid is applied is heat-treated at a temperature of 110 ° C. or higher for 10 seconds or longer.
Stretching with a total draw ratio of 30 times or less was carried out,
The polyethylene fibrous material is characterized by being unstretched or stretched at a magnification less than the total stretch ratio.
The method for producing a polyethylene fiber according to any one of claims 1 to 3.