JPH0116950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for uniformly and economically modifying synthetic fibers with excellent reaction efficiency.

(Prior art) Conventionally, as a method for efficiently grafting hydrophilic vinyl monomers onto hydrophobic synthetic fibers,
These include No. 27744 and Special Publication No. 59-5126.

The former proposes a pretreatment method (activation method) to achieve efficient graft polymerization, but there is no specific disclosure of the means itself for graft polymerizing monomers, and the latter proposes the composition of monomers to be graft-polymerized, but the method for graft polymerization is to apply the monomers by immersion heating, padding, spraying, coating, transfer, etc., followed by heating and steam treatment, or Only a method of heat treatment is disclosed. Such immersion heating method has a large amount of unreacted monomer, does not improve grafting efficiency, and also causes drainage problems. In addition, other methods do not provide high grafting efficiency, and in some cases, graft polymerization may not occur at all. It is difficult to say that either method is economically superior.

(Problems to be Solved by the Invention) In view of these conventional drawbacks, the present invention provides a method for uniformly and economically modifying synthetic fibers with excellent grafting efficiency.

(Means for Solving the Problems) In order to achieve the above object, the present invention adopts the following configuration. That is, in a method of modifying synthetic fibers by graft polymerizing monomers, a 3 to 50% monomer aqueous solution is picked up on the fibers.
This is a method for modifying synthetic fibers, which is characterized by applying heat in a range of 30 to 150% and then heat-treating in a closed system using a high-frequency heating method.

(Description of Means) The synthetic fibers used in the present invention are fibers made of ordinary fiber-forming synthetic resins, and include, for example, polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyolefin fibers, etc. Furthermore, it includes fibers made of these modified polymers, mixtures thereof, or mixed fibers in various forms in which these are combined with natural fibers. These synthetic fibers may be in any form such as tow, thread, knitted fabric, or nonwoven fabric.

The monomer used in the present invention is a compound containing at least one polymerizable unsaturated group, which is usually applied to graft polymerization, and can be applied regardless of its molecular weight.

Such monomers include, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid; unsaturated amides such as acrylamide, methacrylamide, N-methylolacrylamide, and vinylpyrrolidone; and vinylphosphones. Examples include various unsaturated compounds such as unsaturated phosphorus compounds such as acids, and unsaturated aromatic compounds such as vinyl sulfonic acid and styrene sulfonic acid. In the present invention, derivative compounds of these monomers can also be applied. Examples of such derivative compounds include, for example, polyethylene glycol monoacrylate, polyethylene glycol dimethacrylate, acrylamide EO adducts, which are obtained by adding ethylene oxide to the above monomers, and perfluoroethyl acrylate, which is an ester bond of perfluoroethyl alcohol. I can give you something,
It is not necessary to be limited to these monomers, and in short, any compound containing a polymerizable unsaturated group can be applied as the monomer of the present invention. Such monomers can be applied alone or in mixtures.

In such a monomer composition, methacrylic acid and/or acrylic acid may be incorporated, including at least about 40% by weight of methacrylic acid; It is preferable to add and blend other monomers in a range of 80% by weight from the viewpoint of improving grafting efficiency.

The present invention is characterized by the solution concentration when grafting is performed using such monomers or monomer compositions. That is, graft polymerization is initiated by performing sealed heat treatment using a treatment liquid having a specific monomer concentration.

By the way, as mentioned earlier, the
The issue describes applying monomers to fibers by padding, spraying, coating, etc., and then subjecting them to heated steam treatment or heat treatment. There is no mention at all that a closed system is essential for the heat treatment in order to improve the grafting efficiency, and there are no examples regarding this.

The present inventors are able to perform graft polymerization with high efficiency without producing a surface homopolymer as a by-product when the monomer concentration is in the range of 3% to 50%. If the concentration exceeds this range, although the grafting rate increases slightly, the grafting efficiency decreases, making it impossible to carry out practical and economical processing. Further, the system for performing the above-mentioned processing treatment is necessary in order to prevent the monomer vapor from scattering during heating. Furthermore, replacing the remaining air with a gas that does not inhibit polymerization, such as nitrogen, gives preferable results, but is not always essential.

Materials constituting a closed system include metal containers and devices, but are not necessarily limited to these; covering the object with a film or glue is also a simple means to achieve a closed system. Applicable.

The method of imparting active points to the object to be treated may be selected as appropriate, such as by adopting the method described in Japanese Patent Publication No. 1982-2774 when imparting a polymerization initiator, or by forming active points by plasma irradiation, radiation irradiation, etc. It is possible.

The object to be treated to which such a polymerization initiator or polymerization active site has been provided is then applied with a treatment liquid comprising a monomer or a monomer composition. In this case, the amount of adhesion may be adjusted by squeezing the treatment liquid with a mangle or the like.

The pick-up amount at this time is preferably 30 to 150% (based on the weight of the fiber). If it is less than 30%, the amount of attached moisture is too small, resulting in poor thermal conductivity during sealed heating, and the carrier effect of water itself (fiber swelling effect).
becomes smaller and the grafting efficiency decreases. on the other hand,
On the other hand, if it exceeds 150%, the water content is too high, making it difficult to raise the temperature of the entire object (workpiece, monomer aqueous solution), and the movement of the monomer aqueous solution on the workpiece becomes too large, resulting in uneven grafting. become the cause.

The monomer-loaded workpiece is then transferred to a closed system.

When a workpiece transferred to a closed system is heat-treated while being left still, the processing liquid usually moves downward due to its own weight, and preferably the workpiece does not move due to centrifugal force. It is preferable to maintain the liquid in a state with little liquid movement by rotating it to a certain degree.

The heating means used in the present invention is a high-frequency heating method, and this means is excellent in temperature increase rate and ease of control, and also exhibits the characteristics of achieving excellent grafting efficiency in a short time. Examples of such heating devices include a high-frequency processing machine manufactured by Ashida Seisakusho Co., Ltd. and an Apollotex electronic reactor (microwave processing machine) manufactured by Ichikin Kogyo Co., Ltd.

When using this heating method, the temperature increase rate varies depending on requirements such as frequency, type and amount of dielectric material, and movement speed of the object to be processed, but by adjusting each of these, the temperature increase rate and maximum temperature can be regulated. I can do it.

Graft polymerization initiation temperature varies somewhat depending on the type of active site, polymerization initiator, type of monomer, etc.
Usually 80℃ or higher, preferably 100℃ or higher and at most 130℃
Temperature conditions up to ℃ apply.

(Example) Example 1 A processed yarn fabric (#25 manufactured by Toray Industries, Ltd.) made of unprocessed polyethylene terephthalate fibers from the scouring intermediate set was treated with 2 g of organic peroxide (Niper MT-80 manufactured by Nippon Oil & Fats Corporation) as a radical polymerization initiator. 10 g of monochlorobenzene as a swelling agent for polyethylene terephthalate fibers and 5 g of a surfactant (Plysurf A-217E manufactured by Daiichi Kogyo Seiyaku) were mixed and diluted with water to form an emulsion (1). Using this as a pretreatment liquid, the above fabric was immersed at a bath ratio of 1:30, and
It was treated at ℃ for 30 minutes and washed with water. Then, after immersing the fabric in an aqueous solution of an equal weight mixture of acrylic acid and methacrylic acid (monomer concentration 10-100%),
The fabric was squeezed with a mangle, wrapped around a glass rod as a core, and then sealed with a polypropylene film.The fabric seal was placed in a container of a high-frequency processing machine manufactured by Ashida Seisakusho Co., Ltd., and heated to 100°C with steam. The temperature rises,
High frequency heat treatment was performed for 5 minutes while controlling the inside of the container to that temperature. The amount of monomer solution picked up at the time of squeezing with a mangle was 88% of the weight of the fabric.

After the heat treatment, the dry weight was measured to determine the weight increase with respect to the initial weight. Next, in order to neutralize the increased weight of acrylic acid and to extract the homopolymer, 1.5 times the equivalent weight of acrylic acid was added.
It was treated in an aqueous solution containing Na ₂ CO ₃ at 60° C. for 30 minutes. Then, add a large excess of acrylic acid aqueous solution to 80°C.
After treating for 1 hour to remove Na ⁺ ions inside the fibers, the dry weight was measured and the weight increase rate with respect to the initial weight was determined.

The monomer grafting efficiency corresponding to the weight increase rate was calculated as follows, taking into account the amount of pick-up.

Grafting efficiency (%) = Weight increase rate (%) × 100/0.88 ×
Concentration (%) These results are shown in Figure 1.

As is clear from Figure 1, if the concentration of the monomer solution in which the object to be treated is immersed is 50% or less, 50%
It can be seen that monomers can be grafted into fibers with a high grafting efficiency of more than %.

For comparison, the above monomer aqueous solution (concentration: mixed monomer 20g/) of Example was used at a bath ratio of 1:30.
The same treatment as in Example 1 was carried out except that graft polymerization was carried out by the in-solution treatment method (110° C. x 1 hour).

The grafting rate of this product was 15% and the grafting efficiency was 25%.

Furthermore, as a comparison, in Example 1, instead of the high frequency heating method, a Hi-Di type dyeing machine (Todoroki Sangyo Co., Ltd.) was used.
The woven fabric squeezed by the mangle is put into the pot of the dyeing machine, and the dyeing machine is sealed in a nitrogen atmosphere.
Heat treatment was performed at 110°C for 1 hour (Comparative Example 2).

The grafting rate and grafting efficiency of this product are shown in FIG. As is clear from FIG. 1, Example 1 is significantly superior to Comparative Example 2 in both grafting rate and grafting efficiency.

Next, changes in heating time and grafting rate in each method of Example 1 and Comparative Example 2 were tracked when the monomer concentration was 30%. The results are shown in Figure 2.

As is clear from FIG. 2, in the method of Example 1, the grafting rate almost reaches equilibrium after 2 minutes, but
It can be seen that in the method of Comparative Example 2, equilibrium is reached after 50 minutes of heating time.

(Effects of the Invention) According to the present invention, synthetic fibers can be uniformly modified extremely economically and in a short time with excellent grafting efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between monomer concentration, grafting efficiency, and grafting rate according to the grafting method of the present invention. FIG. 2 is a graph showing changes in heating time and grafting ratio in Example 1 and Comparative Example 2. In the table, 1: grafting rate of Example 1, 1': grafting rate of Comparative Example 2, 2: grafting efficiency of Example 1, 2': grafting efficiency of Comparative Example 2.

Claims (1)

[Claims] 1 In a method of modifying synthetic fibers by graft polymerizing monomers, a 3-50% monomer aqueous solution is applied to the fibers in a pickup amount of 30-150%, and then heat treatment is performed using a high-frequency heating method in a closed system. A method for modifying synthetic fibers, characterized by: