JP3293031B2 - Manufacturing method of grafted fiber by film sealing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing grafted fibers for imparting functions such as hydrophilicity, hygroscopicity, antistatic properties, adhesiveness and antibacterial properties to various fibers with good durability.

[0002]

BACKGROUND OF THE INVENTION Graft polymerization is a useful method for imparting permanent functionality to fibers. Until now,
The main known graft polymerization methods include a chemical graft polymerization method using a thermopolymerizable initiator such as a peroxide, a graft polymerization method using low-temperature plasma, and a radiation graft polymerization method. In the chemical graft polymerization method, fibers such as cotton and rayon easily undergo graft polymerization, but practically stable graft polymerization does not easily occur in chemically stable fibers such as polyesters and polyolefins, and chlorine-based fibers have an adverse effect on the environment. It is necessary to use a solvent as a swelling agent and to react at a high temperature. In addition, the method in which active species are produced on fibers by low-temperature plasma and graft polymerization is performed is a process in a vacuum, which is not industrially suitable.

[0003] Radiation graft polymerization is a method in which active species are generated by irradiation with radiation, regardless of the fiber material, and the graft polymerization can be easily performed under atmospheric pressure. However, the radiation graft polymerization method using gamma rays has a drawback that irradiation requires several tens of hours due to its low dose rate, and is not suitable for fiber processing. Among radiations, electron beams have a high dose rate, and irradiation can be performed in seconds, which is a method suitable for fiber processing. Until now, methods for modifying fibers by electron beam irradiation can be broadly classified as follows.
Two methods have been proposed.

[0004] The first method is a polymerization method called pre-irradiation method, in which a fiber material is first irradiated with an electron beam in an atmosphere having a low oxygen concentration to form active species on the fiber surface or inside thereof, and radicals are formed. By immersing in a polymerizable compound solution, graft polymerization is performed. However, in this method, when the fiber irradiated with the electron beam is exposed to air, the generated active species is attenuated. Therefore, it is necessary to store the fiber under cooling in an inert atmosphere or to carry out graft polymerization immediately. The second method is a polymerization method called a simultaneous irradiation method. First, a fiber material is impregnated with a radically polymerizable compound, and then the fiber material is opened in a low oxygen concentration atmosphere under the coexistence of a monomer and a fiber. It is a method of irradiating an electron beam in a system and reacting. This method is easier to industrialize than the above-mentioned pre-irradiation method. However, in this method, it is necessary to impregnate the inside of the fiber with the radical polymerizable compound in advance and then irradiate the fiber with an electron beam. Fibers that are hardly impregnated with radically polymerizable compounds, for example, polyethylene terephthalate (polyester) fibers, have a high crystallinity. It is necessary to use a solvent or a benzene-based solvent such as benzyl alcohol to swell the fibers, or to add a halogen-based solvent or a benzene-based solvent to the radically polymerizable compound. However, halogen-based solvents and benzene-based solvents are becoming unusable environments because they have a negative effect on carcinogenicity and the environment. In addition, if the electron beam is irradiated without impregnating the inside of the fiber with the radical polymerizable compound, a high graft ratio cannot be obtained, and the homopolymer due to the local volatilization of the radical polymerizable compound attached to the fiber surface can be obtained. And uneven grafting are observed.

[0005]

In the conventional simultaneous irradiation method using an electron beam, a fiber having a high graft ratio cannot be obtained unless the radical polymerizable compound is impregnated into the inside of the fiber.
Here, a high graft ratio means a graft ratio of a radical polymerizable compound of 3% or more. In order to sufficiently impregnate the radical polymerizable compound, it is necessary to use a solvent having a bad influence on the environment, such as a halogen solvent or a benzene solvent, which is not preferable. In addition, solvents with low environmental impact, such as water and lower alcohols, swell the fiber sufficiently and cannot impregnate the radically polymerizable compound sufficiently. Even when irradiated with an electron beam, a high graft ratio can be obtained. In addition to this, there is a problem that a homopolymer is generated due to local volatilization of the radical polymerizable compound attached to the fiber surface and graft unevenness is observed. An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a grafted fiber using an electron beam for uniformly and radically polymerizing a radical polymerizable compound onto various fiber materials to the inside of a fiber filament. And

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the fibers provided with the radical polymerizable compound solution from which dissolved oxygen has been removed in advance have been separated into two polymer films. The present inventors have found that uniform grafted fibers with a high graft ratio can be obtained by irradiating an electron beam from the polymer film and then polymerizing by heating, by covering and sealing with a polymer. did. That is, in the present invention, a fiber and a radical polymerizable compound are hermetically sealed between films using a polymer film, and an electron beam is irradiated from above the polymer film. By sealing with a film in this manner, the fiber and the radical polymerizable compound are shielded from oxygen in the air during electron beam irradiation, so that deactivation of radicals by oxygen in the air is less likely to occur. At the same time, volatilization of the radical polymerizable compound can be prevented, and the graft polymerization is started uniformly. Even when using a radical polymerizable compound solution with a low swelling property to the fiber, the irradiation of the electron beam causes the generated polymer radical to react with the radical polymerizable compound on the surface of the fiber filament and initiate polymerization. . At this time, the graft state after the electron beam irradiation is such that the graft layer is only formed on the surface layer of the fiber filament and the graft layer has not sufficiently grown to the inside of the fiber filament. Further, after the electron beam irradiation, the post-polymerization easily proceeds by heating the irradiated sample in an air atmosphere. Since it is sealed with a film, it suppresses the entry of oxygen in the air and the volatilization of the radically polymerizable compound, so that post-polymerization is possible. After this polymerization, unreacted radically polymerizable compound diffuses and penetrates into the graft layer formed on the filament surface layer, and the radically polymerizable compound reacts with polymer radicals present inside the fiber. As the process proceeds, the thickness of the graft layer increases. In the grafted fiber produced by this method, the homopolymer can be easily removed, there is no sticking between the fiber filaments, and the texture is almost unchanged from the untreated fiber. In this method, it is not necessary to previously impregnate the inside of the fiber with a solvent that adversely affects the environment with the radical polymerizable compound, and the graft polymerization into the fiber can be performed by heat treatment after electron beam irradiation. Therefore, a high graft ratio that can be functionalized can be easily produced.

Hereinafter, the present invention will be described in detail. The fibers applicable in the present invention are natural fibers such as cotton and silk, and synthetic fibers such as polyester, nylon, polyethylene, and polypropylene.
(Nonwoven fabric), etc., and is not particularly limited.

[0008] The radical polymerizable compound used in the present invention is a compound which forms a bond with a polymer radical formed on a fiber by electron beam irradiation.
Unsaturated compounds having an acidic group such as methacrylic acid, itaconic acid, methacrylsulfonic acid, and styrene sulfonic acid, and unsaturated carboxylic acid amides such as esters thereof, acrylamide and methacrylamide, and unsaturated compounds having a glycidyl group or a hydroxyl group at a terminal. , Vinylphosphonate and other unsaturated organic phosphates, and basic (meth) acrylates such as quaternary and tertiary ammonium salts, fluoroacrylate, acrylonitrile, and the like, but are not limited thereto. These can be used alone or in combination of two or more.

The above-mentioned radically polymerizable compound may be an organic solvent such as water or lower alcohol, or a dilute solution using a mixed solution thereof as a solvent. The concentration of the radically polymerizable compound in the diluted solution varies depending on the desired graft ratio, but can be adjusted to 1 to 70% by volume. When a radical polymerizable compound that easily forms a homopolymer is used, the formation of the homopolymer may be suppressed by adding a metal salt of copper or iron to a diluted solution of the radical polymerizable compound.

[0010] The polymer film used for coating in the present invention is a film capable of preventing oxygen permeation and volatilization of the radical polymerizable compound, and having heat resistance and no elution of a plasticizer or the like from the film. It is necessary that the material does not easily undergo its own graft polymerization. If a film such as polyethylene or tetrafluoroethylene is irradiated with an electron beam, graft polymerization also occurs on the film surface, and the fiber and the film adhere strongly, and in a later step,
It becomes difficult to peel off the fiber and the film. Among the commercially available films, a polyethylene terephthalate film having low efficiency of generating polymer radicals by electron beam irradiation and low oxygen permeability is most suitable. The thickness is preferably 0.01 to 0.2 mm, which is flexible. 0.0
With an extremely thin film of 1 mm or less, the handleability is poor. On the other hand, with a thickness of 0.2 mm or more, the penetration of an electron beam is hindered, so that a graft reaction hardly occurs.
There is no need to use thick films in terms of economy. Next, the method of sealing fibers using a film is described.
Using two films unwound from two rolls, it is only necessary to sandwich the fiber provided with the radically polymerizable compound solution from above and below and seal it so that air bubbles do not remain. At this time, the radical polymerizable compound solution may be injected between the films if the amount of the radical polymerizable compound solution attached is small due to the fiber structure and the entire surface of the film is not filled with the solution. Also, both sides of the film need not be bag-shaped, but may be a cut sheet-shaped film. The space between the two films is filled with the radical polymerizable compound solution, in other words, the water-sealed structure can suppress the invasion of air. The irradiation target, which is a fiber containing a radical polymerizable compound solution sealed with a film, is preferably thin and uniformly flat. This is because electron beams have lower penetrating power than gamma rays. Therefore, when irradiating an electron beam, the distance from the window from which the electron beam is emitted to the object to be irradiated must be uniform. Differences occur in the dose applied to the irradiated object, resulting in uneven graft polymerization.

Since the accelerating voltage of the electron beam irradiator is proportional to the penetrating power of the electron beam, it can be appropriately determined by the total thickness of the treated cloth, the polymer film used for coating, and the radical polymerizable compound solution. , Acceleration voltage 150-800
A kilovolt (hereinafter abbreviated as “kV”) is appropriate. The irradiation dose of the electron beam may be appropriately determined in consideration of the desired performance and the deterioration of the physical properties of the fiber caused by the irradiation.
Gy ”. ) Is appropriate, preferably 5
0 to 200 kGy. If the irradiation dose is less than 10 kGy, the generation of active species necessary for a sufficient amount of graft polymerization does not occur. If the irradiation dose exceeds 300 kGy, the degradation of the physical properties of the radiation-resistant polyester fiber due to the cleavage of the main chain undesirably occurs. The atmosphere at the time of electron beam irradiation may be either air or an inert gas atmosphere such as nitrogen or helium, since the atmosphere is sealed with a polymer film.
Since there is no effect on the graft polymerization by the irradiation atmosphere, irradiation in air is appropriate in consideration of economic efficiency. Also,

In the present invention, it is necessary to carry out heat polymerization after electron beam irradiation. The heat polymerization is a process in which a fiber sealed with a polymer film irradiated with an electron beam is heat-treated at that temperature for 10 minutes to 120 minutes. The temperature condition at this time is preferably 40 to 80 ° C. 40
If the temperature is lower than ℃, the polymerization rate is too slow to obtain a sufficient graft ratio. At 80 ° C. or higher, the termination reaction of polymerization due to the bonding between the graft chains occurs preferentially. The temperature and time of the heat polymerization may be arbitrarily set within the above range according to the intended graft ratio. The atmosphere for post-polymerization is sufficient in air. In the present invention, since the fiber is covered with the polymer film and the diffusion of oxygen in the air to the fiber and the volatilization of the radical polymerizable compound are suppressed, post-polymerization becomes possible, and graft polymerization is performed inside the fiber. Progress,
Graft rate increases.

Next, the manufacturing process of the present invention will be described. The fibers are immersed and passed through a tank of a radically polymerizable compound solution from which dissolved oxygen has been removed by aeration with nitrogen gas, so that the fibers are retained for a predetermined period of time, so that the radically polymerizable compound is sufficiently applied to the cloth and taken out of the solution tank. At this time, the radical polymerizable compound solution and the fiber are sealed between the two polymer films unwound from the roll. Next, the fiber sealed with the polymer film is irradiated with an electron beam. The fiber irradiated with the electron beam is heated for a predetermined time in a heat treatment step,
Post-polymerization is performed. The post-polymerized fabric is separated from the polymer film, and is passed through a washing tank and a dryer to continuously obtain grafted fibers.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the embodiments of the present invention will be described in more detail with reference to Examples. Measurements and evaluations such as the performance of fibers in the Examples were carried out by the following methods. (1) Graft ratio The graft ratio of the radical polymerizable compound is determined by the fiber dry weight before the reaction (W1) and the fiber dry weight after the graft reaction (W2).
Was calculated as follows. Graft rate = (W2-W1) / W1 × 100 (%)

(2) Hygroscopicity (moisture content at the time of moisture absorption) The moisture content at the time of moisture absorption is determined by drying a sample cloth at 50 ° C. for 2 hours with a vacuum dryer (W3). Next, 30
The sample is put in a thermo-hygrostat at 95 ° C. and 95% RH for 60 minutes, and the weight of the absorbed sample is measured (W4). From the above measurement results, it was calculated by the following equation. Moisture content at the time of moisture absorption (Abs) = (W4−W3) / W3 × 10
0 (%) As the acrylic acid grafted fiber, a sample treated with a 1% aqueous sodium hydrogen carbonate solution was used. (3) Uniformity of Graft Polymerization by Dyeing The uniformity of the graft polymerization was visually confirmed by dyeing a cationic dye on the fibers grafted with acrylic acid. If the dyeing method is specifically shown, kayakyl brilliant pink (B-ED) is 3% by weight based on the fiber weight,
Bath ratio 1: 120,80 in a bath containing sodium acetate and acetic acid
After staining at 15 ° C. for 15 minutes, the mixture was washed with a 0.5% acetic acid aqueous solution, washed with water, and dried.

Example 1 A 50% aqueous solution of acrylic acid (a composition of acrylic acid: water = 50: 50 (volume ratio)) to which copper sulfate was added so as to have a concentration of 0.003 mol / liter was prepared, and nitrogen gas was used. The dissolved oxygen was removed by aeration. A taffeta made of polyester fiber (vertical: 75d / 36f, 110 / inch, horizontal: 7)
(5d / 36f, 80 pieces / inch) and sealed with two 25 μm polyester films. At this time, the total thickness of the object to be irradiated of the cloth (thickness: 60 μm), the film and the acrylic acid solution layer is about 150 μm, and the electron beam transmission power at an acceleration voltage of 250 kV (about 250 μm)
Was within the range. An acceleration voltage of 25 from the film
Electron beam irradiation was performed at room temperature in an air atmosphere at 0 kV, irradiation dose of 100 kGy. Subsequently, the sample irradiated with the electron beam was treated at 50 ° C. for 1 hour in an air atmosphere to perform heat polymerization. In order to remove unreacted acrylic acid, each was washed with a 1% aqueous sodium hydrogen carbonate solution, a 1% aqueous acetic acid solution, and warm water at 80 ° C. for 30 minutes each and then dried with hot air to obtain an acrylic acid graft cloth.

(Comparative Example 1) For comparison with the present invention, treatment was carried out under exactly the same conditions as in Example 1 except that a polyester film was not sealed using a polymer film. (Comparative Example 2) For comparison with the present invention, after irradiation with an electron beam,
The treatment was performed under exactly the same conditions as in Example 1 except that the treatment was not performed at 50 ° C. for 1 hour.

Example 1 of the present invention and Comparative Examples 1 and 2
Table 1 shows the results of the graft ratio, the moisture content during moisture absorption, and the uniformity of the graft polymerization by dyeing. According to Table 1, when the film was not sealed with the film of Comparative Example 1, almost no graft was obtained. However, in Example 1 according to the present invention, it was confirmed that the graft ratio was very high, the uniformity by dyeing was good, and high hygroscopicity was exhibited. In Comparative Example 2 in which the heat treatment after electron beam irradiation in Example 1 was not performed, the graft ratio was low, but compared with Example 1, although the color tone was slightly faint, it was dyed uniformly. From this, the superiority of the present invention was recognized.

[0019]

[Table 1]

Further, in order to confirm whether the acrylic acid polymer was present inside the fiber filaments, the grafted fibers were used for the samples of Example 1 and Comparative Example 2.
A silver ion was adsorbed on the carboxyl group of polyacrylic acid by immersion treatment in a mM silver nitrate solution at 80 ° C.
μm) was analyzed. The result is shown in FIG. In the sample of Comparative Example 2, grafting was performed only from the surface to a depth of about 10% of the radius of the filament. In the sample of Example 1, about 65% of the radius of the filament was grafted.
The presence of silver was confirmed to the depth of
It was confirmed that acrylic acid was grafted to the inside of the fiber.

[0021]

FIG.

Example 2 A 30% glycidyl methacrylate solution (composition of glycidyl methacrylate: methanol = 30: 70 (volume ratio)) to which copper chloride was added so as to have a concentration of 0.003 mol / liter was prepared. The dissolved oxygen was removed by aeration. After immersing a polypropylene non-woven fabric (70 g / m ² ) in this solution,
Sealed with two 25 μm polyester films. At this time, the total thickness of the object to be irradiated of the cloth (thickness of 100 μm), the film and the acrylic acid solution layer was about 200 μm,
Electron beam penetration force at an acceleration voltage of 250 kV (about 250 μm
Degree). From above the film, accelerating voltage 250kV, irradiation dose 100kGy, in air atmosphere,
Electron beam irradiation was performed at room temperature. Subsequently, the sample irradiated with the electron beam was treated at 50 ° C. for 1 hour in an air atmosphere to further perform heat polymerization. In order to remove unreacted glycidyl methacrylate, each was washed sequentially with tetrahydrofuran and methanol for 30 minutes each and then dried with hot air to obtain a grafted nonwoven fabric. Next, the nonwoven fabric grafted with glycidyl methacrylate was treated in a 2N aqueous sulfuric acid solution at 70 ° C. for 2 hours to convert the epoxide group as a graft chain into a diol group.

Comparative Example 3 For comparison, the same treatment as in Example 2 was performed except that the polypropylene nonwoven fabric was not sealed with a polymer film. Table 2 shows the graft ratio and the water contact angle (measured at 10 points of a 10 cm × 10 cm sample) of Example 2 and Comparative Example 3. From these results, in Example 2, graft polymerization easily occurred even with glycidyl methacrylate, and a high graft ratio of 30% was obtained. In addition, it can be seen that the hydrophobic treatment after the grafting makes the hydrophobic polypropylene fibers evenly hydrophilic.

[0024]

[Table 2]

[0025]

According to the conventional simultaneous irradiation method using impregnation using an electron beam, it is necessary to sufficiently impregnate the inside of the fiber with a radical polymerizable compound in advance and then irradiate the electron beam in a nitrogen atmosphere. However, in the method of the present invention, even in a solution system in which the fiber is not sufficiently impregnated with the radical polymerizable compound, the fiber and the radical polymerizable compound are sealed with a film, irradiated with an electron beam, and further heated and polymerized. Through a series of treatments, a fiber having a uniform graft in the surface direction, grafted to the inside of the fiber, and having a high graft ratio can be easily produced. The functionality of this grafted fiber is permanent and can be applied to clothing, industrial materials, filter materials, etc.

[0026]

[Brief description of the drawings]

FIG. 1 is a component image showing the results of analyzing the samples of Example 1 and Comparative Example 2 with an X-ray microanalyzer in which silver ions were adsorbed to examine the presence of an acrylic acid polymer in the cross section of a fiber filament. is there. Since the white portion of the filament in this figure indicates the presence of silver, the region where the acrylic acid polymer is present can be confirmed.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) D06M 13/00-15/715 C08J 5/04

Claims (2)

(57) [Claims] 1. A grafted fiber, wherein a fiber provided with a radically polymerizable compound is sealed between polymer films, irradiated with an electron beam from above the polymer film, and then heated and polymerized. Manufacturing method. 2. The polymer film has a thickness of 0.01 to 0.2.
The method for producing a grafted fiber according to claim 1, wherein the film is a polyethylene terephthalate film having a thickness of 1 mm.