JP4203188B2 - Method for producing temperature-sensitive discolorable acrylic synthetic fiber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a thermochromic acrylic synthetic textiles. In particular, the thermochromic pigment is contained in a dispersed state in the acrylonitrile polymer, a method of manufacturing a thermochromic acrylic synthetic textiles that without the fibrous form.
[0002]
[Prior art]
Conventionally, as a means for imparting a thermochromic function to the fiber, the surface of the fiber is coated with a thermochromic layer in which a thermochromic pigment is fixed in a dispersed state in a binder resin (Japanese Patent Laid-Open No. 61-179389, specially disclosed). No. 62-156355), a thermoplastic fiber-forming polymer such as polyester, polyamide, polyolefin, and the like, and a thermochromic pigment is melt-blended and integrally formed by melt spinning (Japanese Patent Laid-open No. Hei 3- No. 227402, JP-A-3-161511, and the like.
[0003]
[Problems to be solved by the invention]
By the way, in the case of acrylic synthetic fibers, the thermal properties of the acrylonitrile polymer make it impossible to melt and blend thermochromic pigments integrally and form fibers by melt spinning. In other words, it was necessary to provide a thermochromic function by forming the thermochromic layer described above.
Accordingly, the texture of the acrylic fiber itself is impaired, and it is inevitable that the durability of the washing strength, scratch strength, light fastness and the like is inferior to that of a melt-spun system by melt blending.
On the other hand, in a system by melt spinning, a thermochromic pigment is melt blended with a fiber-forming polymer, or high heat and high pressure are applied in the melt spinning process, which may cause thermal degradation of the thermochromic pigment. In addition, the application of high-molecular-weight, high-melting fiber-forming polymers that can be applied to general fiber products is hindered, and it has been difficult to practically satisfy durability such as fiber strength.
In order to solve the above-mentioned problems, the present inventors proceeded with intensive studies, and the temperature-sensitive discoloration that continuously and effectively expresses the thermochromic function without impairing the texture and fiber properties of acrylic fibers. it is intended to provide a method for manufacturing a sexual acrylic synthetic textiles.
[0004]
[Means for Solving the Problems]
The present invention relates to ( a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) an average particle in which a reaction medium that determines the temperature at which the color reaction of the both occurs is contained in a microcapsule. A thermochromic pigment having a diameter of 0.5 to 30 μm is blended in a dispersed state at a ratio of 0.5 to 40% by weight with respect to the polymer in a concentrated aqueous solution of an inorganic salt in which an acrylonitrile polymer is dissolved. A method for producing a thermochromic acrylic synthetic fiber characterized by wet spinning with a spinning dope is a requirement.
Furthermore, inorganic salts concentrated aqueous solution is a requirement that it is a concentrated aqueous solution containing thiocyanate salt as a main component.
[0005]
The thermochromic pigment comprises (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound that colors the compound, and (c) a reaction medium that determines the occurrence temperature of the color reaction of both. Those known in the art including the essential three components are effective. Specifically, Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398 proposed by the present applicant. Can be used. The above color changes before and after a predetermined temperature (discoloration point), exhibits a decolored state at a temperature range above the discoloration point, and develops a color state at a temperature range below the discoloration point. Only one of the states can exist. That is, the other state is maintained while the heat or cold necessary to develop the state is applied, but when the heat or cold is not applied, the state returns to the state exhibited in the normal temperature range. _A heat-erasable type (A) having a characteristic having a relatively small width (ΔH _A = 1 to 7 ° C.) can be mentioned, and in particular, a system in which ΔH _A is 3 ° C. or less [shown in Japanese Patent Publication No. 1-292998 A fatty acid ester having a ΔT value (melting point-cloud point) of 3 ° C. or lower is applied as the component (c)], which is sensitive to temperature changes at the color change point and exhibits high sensitivity to heat decolorization. It can be effectively applied according to the purpose (see FIG. 5).
[0006]
In addition, the large hysteresis characteristics (ΔH described in Japanese Patent Publication No. 4-17154, Japanese Patent Application Laid-Open No. 7-179777, Japanese Patent Application Laid-Open No. 7-33997, Japanese Patent Application Laid-Open No. 8-39936, etc. proposed by the present applicant. _B = 8 to 50 ° C.), that is, the shape of the curve plotting the change in color density due to the temperature change is higher than the color change temperature range, contrary to the case where the temperature is raised from the lower temperature side than the color change temperature range. The color changes by following a path that differs greatly from the case of descending from the lower temperature range, and the color development state at a low temperature range of t ₁ or lower or the decolored state at a high temperature range of t ₄ or higher is a specific temperature range [t _{2 to} t _A color memory retention type thermochromic composition (B) capable of storing and retaining in a temperature range between ₃ (substantially two-phase retention temperature range) is also applicable (see FIG. 6).
The substantially two-phase holding temperature range includes a normal temperature range (for example, 15 to 35 ° C.), but is not limited to the temperature range.
[0007]
According to the proposals of the present applicant (Japanese Patent Laid-Open Nos. 11-129623 and 11-5973) that develop color by heating from a decolored state as the composition of the heat-coloring type (C), (b) Examples of the electron accepting compound include a system to which a specific alkoxyphenol compound having a linear or side chain alkyl group having 3 to 18 carbon atoms is applied.
[0008]
A temperature-sensitive color-changing acrylic synthetic fiber having various color-changing forms is provided by selecting and applying a pigment containing the above-described three types (A, B, C) of the thermochromic composition according to the purpose. it can.
[0009]
The thermochromic pigment contains three components (a), (b), and (c) in a microcapsule from the standpoints of vivid color development, high color density, homogeneity, dispersion stability, chemical resistance, and the like. ash of it is effective.
The average particle size [(major axis + minor axis) / 2] of the thermochromic pigment is in the range of 0.5 μm to 30 μm, preferably 0.5 to 15 μm, more preferably 0.5 to 10 μm. Is effective in terms of color change sensitivity, endurance, processability, and the like.
In a system having a particle diameter of more than 30 μm, it is difficult to form a fiber exhibiting stable quality thermochromic properties due to lack of homogeneous dispersibility in the fiber forming process.
In a system of less than 0.5 μm , even if a thermochromic pigment microencapsulated in a suspended state in an aqueous medium is obtained, the encapsulated pigment can be isolated by means such as filtration or centrifugation. There are difficulties and strength is insufficient.
[0010]
Microencapsulated form of Pigment does not refuse the application of those true circular cross section, having a non-circular cross-sectional shape, a non-circular shape of the thermochromic pigment further having a recess in at least a part of the specific outer surface (See FIGS. 1 to 4) can be effectively applied.
Since the thermochromic pigment is a non-circular flat pigment, it can be elastically deformed and relieve stress appropriately under pressure and heat load, so it has an effect of suppressing capsule wall membrane destruction. Fulfill. That is, during the heating process, the wall membrane elastically deforms in response to the thermal expansion and contraction of the capsule, thereby preventing the capsule wall membrane from being destroyed, protecting the reversible thermochromic composition of the capsule and It effectively functions as a thermochromic pigment in the form of a tough capsule that retains the thermochromic function.
Further, encapsulated thermochromic Pigments of the present invention is preferably in the range of reversible thermochromic composition / wall membrane = 7 / 1-1 / 1 (weight ratio). When the ratio of the thermochromic composition is larger than the above range, the thickness of the wall film becomes too thin, and the protective function of the encapsulated thermochromic composition is reduced. On the other hand, when the ratio of the wall film is larger than the above range, the color density is inevitably lowered, which is not preferable.
[0011]
As a means for encapsulating the reversible thermochromic composition in a capsule, a known encapsulation method such as an interfacial polymerization method, an interfacial polycondensation method, an in situ method, a coacervate method, or the like is applied. In order to obtain a thermochromic pigment having a particle size range and an outer shape satisfying the above conditions, an interfacial polymerization method or an interfacial polycondensation method that hardly causes aggregation or coalescence is preferably used. Furthermore, after completion of the encapsulation, unnecessary coarse particles are removed by diluting the capsule suspension with water as desired, and filtering out impurities and coarse particles using filters.
[0012]
The thermochromic pigment is blended at a ratio of 0.5 to 40% by weight with respect to the acrylonitrile polymer forming the fiber. If it is less than 0.5% by weight, no sharp thermochromic property is exhibited. On the other hand, if it exceeds 40% by weight, a color residue at the time of decoloring tends to occur, and it is preferably in the range of 1 to 20% by weight.
[0013]
The method for producing a thermochromic acrylic synthetic fiber of the present invention determines (i) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) an occurrence temperature of the color reaction of both. A thermochromic pigment having an average particle size of 0.5 to 30 μm encapsulating the reaction medium in microcapsules is 0.5 to 40 wt% with respect to the polymer in a concentrated inorganic salt solution in which an acrylonitrile-based polymer is dissolved. It is a requirement to perform wet spinning with a spinning dope blended in a dispersed state at a rate of%.
Examples of the concentrated aqueous salt solution include concentrated aqueous solutions of rhodan salts such as rhodium soda, rhodan potassium, rhodanammon and rhodium calcium, and concentrated aqueous solutions of inorganic salts such as zinc chloride and lithium chloride. These inorganic salts act as a good solvent for the acrylonitrile polymer without deteriorating the color changing function of the thermochromic pigment. As the coagulation bath for coagulating the filament-like material discharged from the spinning nozzle, conventional water or an aqueous solution of the above inorganic salt having a concentration of 20% or less is suitable.
The spinning dope is adjusted so that a spinning solution having suitable characteristics can be obtained according to the degree of polymerization of the polymer, but usually has a viscosity of about 40 to 200 poise at 30 ° C. It is valid.
Examples of the acrylonitrile-based polymer include those containing a second component such as polyacrylonitrile or a copolymer that can be copolymerized with acrylonitrile and polyvinyl chloride, and acrylonitrile is 50% by weight or more, preferably 80% by weight. What contains above is preferable. Examples of the compound that is copolymerized with acrylonitrile to produce an acrylonitrile copolymer product effective in the practice of the present invention include acrylic acid or methacrylic acid esters such as methyl acrylate, ethyl acrylate, and methyl methacrylate, acrylamide, and the like. Methacrylamide and their alkyl-substituted products and nitrogen-substituted products, vinylpyridines such as 2-vinylpyridine, 2-methyl-5-vinylpyridine, styrene and their alkyl-substituted products or even vinyl chloride, vinylidene chloride, Monomers such as vinyl bromide, vinylidene bromide, and vinylidene bromide can be exemplified, but are not necessarily limited thereto.
Usually, the molecular weight (average molecular weight) of the single polymer acrylonitrile or the copolymer acrylonitrile is appropriately selected from the range of 15,000 to 150,000 (generally 25,000 to 80,000).
In the present invention, the composition of the spinning stock solution is a polymer containing a thermochromic pigment in a spinning stock solution of 5 to 30% by weight (preferably about 10 to 20% by weight) of an acrylonitrile polymer, 30 to 60% by weight of rhodan salt or zinc chloride. 0.5 to 40% by weight (preferably 1 to 20% by weight) can be dispersed. Furthermore, general pigments, glittering materials and the like can be added.
The spinning dope is extruded from 45 to 75 ° C. through a spinning nozzle into a coagulating liquid such as a dilute rhodan salt aqueous solution, solidified, and subjected to known water washing, stretching, heat treatment, drying, and further steps such as crimping and oil treatment. Fiber and eggplant.
As thermochromic pigment, applying the pigment in microencapsulated form, it is easily dispersible and has a resistance at the time of preparation of the spinning dope, inter alia, pigments having a non-circular cross-sectional shape, the fiber formation by spinning process and drawing In the process, pressure and high heat are applied, but the stress is relieved by its own elastic deformation, and in addition, the microcapsules are destroyed due to the property that the microcapsule pigment itself is easily oriented in the longitudinal direction during fiberization. And a fiber satisfying the desired thermochromic function can be obtained.
The fiber diameter in the present invention is 100 μm or less, preferably 30 μm or less, and can be put into practical use in the form of tow, staple or other desired fibers by the same treatment as general-purpose non-thermochromic acrylic fibers.
In the wet spinning, in order to obtain a fiber diameter of 30 μm or less, when satisfying the relationship d <D ≦ 20d (where d is the particle diameter of the pigment and D is the fiber diameter), the fiber spinning is continuous and stable. It was found that fiber formation was possible.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Thermosensitive color-changing acrylic synthetic fibers use a spinning stock solution in which a specific amount of thermochromic pigment with a specific particle size is dispersed in an inorganic salt-concentrated aqueous solution containing an acrylonitrile polymer, and is discharged from the spinning nozzle into the coagulation liquid. And after-treatment such as stretching by a known means to obtain a fiber form.
In the examples, among the pigments in the form of microcapsules, the forms illustrated in FIGS. 1 to 4 are applied, but these forms may be mixed or in the form of a circular cross section. The invention is not limited to the examples.
[0015]
【Example】
Examples are shown below. In addition, the part in an Example is a weight part.
[0016]
Example 1
10 parts of an acrylonitrile copolymer obtained by polymerization with a monomer composition of 90 parts of acrylonitrile, 9.8 parts of methyl acrylate, and 0.2 part of sodium methallyl sulfonate are dissolved in 89 parts of a 50% strength by weight aqueous rhodium soda solution. did.
In 99 parts of the acrylonitrile copolymer solution, 1 part of (i) 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, (B) A reversible thermochromic composition comprising 5 parts of 1,1-bis- (4-hydroxyphenyl) -2-methylpropane, (c) 25 parts of cetyl alcohol, and 25 parts of stearyl caprate is converted into a micro-layer of epoxy resin film. Reversible thermochromic pigment encapsulated (discoloration temperature t ₄ : about 33 ° C., color development temperature t ₁ : about 28 ° C., blue color at color development, colorless at color disappearance, average particle size: 3 μm, cross-sectional shape of FIG. Add 1 part of reversible thermochromic composition / wall film = 5.6 / 1.0) and disperse uniformly to obtain 1% by weight of reversible thermochromic pigment, 10% by weight of acrylonitrile copolymer, rhodium soda 44 .5 The amount%, to prepare a spinning solution consisting of 44.5 wt% water.
The spinning dope is discharged into a rhodan soda aqueous solution at −2 ° C. and a concentration of 15% by weight using a spinning nozzle having a pore diameter of 0.04 mm, wet spinning, and further washed with water, stretched, dried and densified under conventionally known conditions, A temperature-sensitive color-changing acrylic synthetic fiber having a fiber diameter of 20 μm was obtained by crimping, heat treatment and oil treatment.
This fiber has a blue color at room temperature (25 ° C.) and has a heat-discoloring type thermochromic property (see FIG. 5), which becomes colorless when heated to a temperature of about 33 ° C. or higher. And left at room temperature (25 ° C.), it turned blue again at about 28 ° C.
This color change could be repeated.
[0017]
Example 2
10 parts of an acrylonitrile copolymer obtained by polymerization with a monomer composition of 88 parts of acrylonitrile and 12 parts of methyl methacrylate were dissolved in 89 parts of a 60 wt% aqueous zinc chloride solution.
99 parts of the acrylonitrile copolymer solution were mixed with (a) 1,2-benz-6-diethylaminofluorane (3 parts), (b) 2,2-bis- (4-hydroxyphenyl) propane (5 parts), (c) Reversible thermochromic pigment in which a reversible thermochromic composition composed of 25 parts of myristyl alcohol and 25 parts of decyl myristate is encapsulated in microcapsules of an epoxy resin film (discoloration temperature t ₄ : about 15 ° C., color development temperature t ₁ : about 10 1 ° C., pink when developing, colorless when decolored, average particle size: 5 μm, cross-sectional shape of FIG. 2, reversible thermochromic composition / wall film = 5.8 / 1.0) 1 part is added and dispersed uniformly As a result, a spinning dope comprising 1% by weight of reversible thermochromic pigment, 10% by weight of acrylonitrile copolymer, 53.4% by weight of zinc chloride, and 35.6% by weight of water was prepared.
The spinning solution is discharged into a zinc chloride aqueous solution at −2 ° C. and 15% by weight using a spinning nozzle having a pore diameter of 0.06 mm, wet-spun, and further washed with water, stretched, and dried and densified under conventionally known conditions. Then, a crimping treatment, a heat treatment, an oil agent treatment, and the like were performed to obtain a thermochromic acrylic synthetic fiber having a fiber diameter of 30 μm.
This fiber is colorless at room temperature (25 ° C.) and has a heat-discoloring type thermochromic property (see FIG. 5), which becomes pink when cooled to a temperature of about 10 ° C. or less. When left at (25 ° C.), it became colorless again at about 15 ° C.
This color change could be repeated.
[0018]
Example 3
10 parts of an acrylonitrile copolymer obtained by polymerization with a monomer composition of 91 parts of acrylonitrile, 6.5 parts of methyl acrylate, and 2.5 parts of N-methylolacrylamide were dissolved in 89 parts of a 50% strength by weight aqueous rhodium soda solution. . In 99 parts of the acrylonitrile copolymer solution, 3 parts of (ii) 1,3-dimethyl-6-diethylaminofluorane, 5 parts of (ro) 1,1-bis- (4-hydroxyphenyl) -2-ethylhexane (C) Reversible thermochromic color memory pigment in which a reversible thermochromic composition comprising 50 parts of neopentyl stearate is encapsulated in an epoxy resin film microcapsule (discoloration temperature t ₄ : about 32 ° C., color development temperature t ₁ : About 15 ° C., orange when colored, colorless when decolored, average particle diameter: 2 μm, cross-sectional shape of FIG. 3, reversible thermochromic composition / wall film = 5.8 / 1.0) 1 part is added and uniform To prepare a spinning dope comprising 1% by weight of reversible thermochromic color memory pigment, 10% by weight of acrylonitrile copolymer, 44.5% by weight of rhodium soda, and 44.5% by weight of water.
The spinning dope is discharged into a rhodan soda aqueous solution at −2 ° C. and a concentration of 15% by weight using a spinning nozzle having a pore diameter of 0.04 mm, wet spinning, and further washed with water, stretched, dried and densified under conventionally known conditions, A temperature-sensitive color-changing acrylic synthetic fiber having a fiber diameter of 15 μm was obtained by crimping, heat treatment and oil treatment.
When the fiber in a decolored state at room temperature (25 ° C.) was cooled to about 15 ° C. or less, it was colored orange, and this colored state could be maintained even when heated to room temperature (25 ° C.) again. Further, the color is erased at about 32 ° C. by heating from the orange colored state, and this state can be maintained until it is cooled to about 15 ° C. or less again. )showed that.
As described above, the fiber has color memory in the normal temperature range, and this color change can be repeatedly performed.
[0019]
Example 4
An aqueous dispersion of a pink pigment as a non-thermochromic colorant with respect to 100 parts of the spinning stock solution of Example 1 (trade name: SANDY SUPER PINK F5B, pigment content: about 14% by weight, manufactured by Sanyo Dye Co., Ltd.) After adding 0.05 part and uniformly dispersing the spinning stock solution into a 15% by weight sodium thiocyanate aqueous solution at −2 ° C. using a spinning nozzle with a pore diameter of 0.04 mm, and after wet spinning, Washing, stretching, drying densification, crimping, heat treatment, oil treatment and the like were performed under known conditions to obtain a thermochromic acrylic synthetic fiber having a fiber diameter of 20 μm.
This fiber has a purple color at room temperature (25 ° C.) and becomes pink when heated to a temperature of about 33 ° C. or higher. When left in this state at room temperature (25 ° C.), the fiber becomes purple again at about 28 ° C. Presented.
This color change could be repeated.
[0020]
Example 5
(I) 3- [2-Ethoxy-4- (N-ethylanilino) phenyl] -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide (1.5 parts), (b) p- 6.0 parts of n-nonyloxyphenol, 4.0 parts of pn-octyloxyphenol, and 30.0 parts of (c) n-docosane are obtained from (a), (b) and (c) of Example 1 above. Applied in place of each component, and thermochromic pigment (average particle size: 3 μm, cross-sectional shape of FIG. 4, reversible thermochromic composition / wall film = 2.8 / 1.0) in the same manner as in Example 1. In the same manner as in Example 1, a temperature-sensitive color-changing acrylic synthetic fiber was obtained.
The thermochromic pigment is in a decolored state (colorless) at a room temperature of 25 ° C., starts to develop color from around 33 ° C. (T ₁ ) when heating is started, and becomes a blue colored state at 43 ° C. (T ₂ ), Next, the color development state is maintained up to 32 ° C. (T ₃ ) in the temperature lowering process, and when the temperature further decreases, the color disappears little by little, and the color disappears completely at 27 ° C. (T ₄ ). And the fiber had the discoloration characteristics.
This color change could be repeated.
[0021]
【The invention's effect】
The thermochromic acrylic synthetic fiber obtained by the method for producing the thermochromic acrylic synthetic fiber of the present invention is one in which a specific amount of a thermochromic pigment having a specific particle diameter is contained in a dispersed state in the fiber. Therefore, compared to a system in which a thermochromic pigment is fixed to the surface with a binder resin, it satisfies the durability such as washing resistance, scratch resistance, light resistance and the characteristics of acrylic fiber, texture, Bulkiness and other fiber characteristics are not impaired, and practicality is satisfied. It has the same fiber characteristics as general-purpose acrylic fibers, and is applied to the toy field such as garments, carpets, blankets, curtains, and stuffed animals.
As thermochromic pigments, to apply the pigment in microencapsulated form, resistant during the preparation of the spinning dope may be dispersible, further, the spinning process is effective even in the heat treatment process, among others, The system having a non-circular cross-sectional shape is rich in elastic deformability due to external pressure, and the pressure due to its own elastic deformation against the pressure in the blending process and the pressure in the fiberizing process. In addition, there is no risk of the microcapsules being destroyed in combination with the property that the microcapsule pigment itself is easily oriented in the longitudinal direction at the time of fiberization, and it is effectively expressed without impairing the desired thermochromic function.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an enlarged explanatory view of (a) appearance and (b) cross section showing an example of a thermochromic pigment applied to a thermochromic acrylic synthetic fiber of the present invention.
FIG. 2 is an enlarged explanatory view of (a) the appearance and (b) the cross section showing another example of the thermochromic pigment applied to the thermochromic acrylic synthetic fiber of the present invention.
FIG. 3 is an enlarged explanatory view of (a) appearance and (b) cross section showing another example of a thermochromic pigment applied to the thermochromic acrylic synthetic fiber of the present invention.
FIG. 4 is an enlarged explanatory view of (a) the appearance and (b) the cross section showing another example of the thermochromic pigment applied to the thermochromic acrylic synthetic fiber of the present invention.
FIG. 5 is a graph showing the discoloration behavior of a heat-decolorable thermochromic composition.
FIG. 6 is a graph showing the discoloration behavior of a color memory retention type thermochromic composition.
FIG. 7 is a graph showing the discoloration behavior of a heat coloring type thermochromic composition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermochromic pigment 11 Thermochromic composition 12 Wall film 13 Indentation t ₁ Complete color development temperature of reversible thermochromic composition by heating decolorization type t ₂ Color development start temperature of reversible thermochromic composition by heating decolorization type t ₃ Decolorization start temperature of the heat decoloring type reversible thermochromic composition t ₄ Complete decoloration temperature of the heat decoloring type reversible thermochromic composition T ₁ Color development start temperature of the heat decoloring type reversible thermochromic composition T ₂ heating complete decoloring temperature [Delta] H _a heat decolorizable decoloring starting temperature T ₄ heating-color forming reversible thermochromic composition of the complete coloring temperature T ₃ heat-coloring type reversible thermal discoloration composition coloring type reversible thermal discoloration composition Hysteresis width of the reversible thermochromic composition ΔH _B Hysteresis width of the _B color memory retention type reversible thermochromic composition ΔH _C Hysteresis width of the _C color development type reversible thermochromic composition

Claims (2)

(B) an electron donating color-forming organic compound, (b) an electron-accepting compound, and (c) an average particle size of 0.5 encapsulated in a microcapsule that determines the temperature at which the color reaction of both occurs. ˜30 μm thermochromic pigment is wetted by a spinning stock solution in which an inorganic salt concentrated aqueous solution in which an acrylonitrile polymer is dissolved is blended in a dispersed state at a ratio of 0.5 to 40% by weight with respect to the polymer. A method for producing a temperature-sensitive color-changing acrylic synthetic fiber characterized by spinning. The method for producing a thermochromic acrylic synthetic fiber according to claim 1, wherein the concentrated inorganic salt aqueous solution is a concentrated aqueous solution containing rhodan salt as a main component.

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