JPS5923566B2 - Electric discharge graft polymerization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for supplying monomers in a discharge graft polymerization (copolymerization) method.

The discharge graft polymerization (copolymerization) method is a method in which the surface of a base material is activated by electrical discharge, and a radically polymerizable monomer is grafted onto the surface of the base material using the active site as a polymerization initiation point.
This method is an excellent surface modification method that can impart new properties to the surface of the substrate.

By this method, the present inventors made the base material hydrophilic, made it water and oil repellent, imparted a permanent antistatic effect, improved adhesiveness,
It has already been discovered that new excellent properties can be obtained, such as promoting or blocking the diffusion of substances, biocompatibility, and improving the depth of the color of fibers.

By the way, in the conventional discharge graft polymerization method, the base material surface is first activated in a discharge activation chamber, and then graft polymerized by being exposed to monomer vapor generated and supplied by heating in a monomer chamber. Ta. However, while conducting research on improving the depth of color of woven fabrics by electrical discharge graft polymerization, the present inventors found that the conventional monomer supply method caused unevenness in the depth of color of woven fabrics. It was discovered that some drawbacks occur.

The monomer chamber is heated to increase the vapor pressure of the monomer, but there are substrate transport rolls and other equipment in the monomer chamber, and it is difficult to equalize the temperature of all of them. It is thought that the resulting temperature distribution within the monomer chamber causes a monomer concentration distribution within the monomer chamber, resulting in non-uniformity in the thickness of the graft polymerized layer. Furthermore, since the temperature of the substrate is lower than the temperature of the monomer chamber, when the substrate enters the monomer chamber, condensation of the monomer occurs on the surface of the substrate. At this time, if there is a concentration distribution within the monomer chamber, there will be a distribution in the amount of monomer condensed onto the surface of the substrate, making the thickness of the graft polymerization layer uneven, resulting in uneven color depth. . Normally, when the graft polymerization layer becomes thicker, the color becomes deeper with a purplish tinge, and conversely, when the graft polymerization layer is thin, the color becomes deeper with a reddish tinge, so if there is significant non-uniformity in the thickness of the graft polymerization layer, Spots appear in the depth of color. In particular, since the depth of the color of the base fabric is improved by graft polymerization, these spots become more noticeable and become a serious drawback. Non-uniformity in the thickness of the graft polymerized layer due to the monomer concentration distribution on the surface of the substrate is not desirable in all applications, including the above-mentioned application of improving the depth of color of woven fabrics.

Therefore, the present inventors conducted intensive research to solve these problems in the discharge graft polymerization method, and as a result, they arrived at the present invention.

However, the purpose is to uniformly supply a monomer to the surface of a substrate in order to form a graft polymerization layer of uniform thickness on the surface of the material in the discharge graft polymerization method. The present invention refers to the method in which, in discharge graft polymerization (copolymerization), when a base material is activated by electric discharge and then brought into contact with a monomer to be grafted, the monomer is mixed with the monomer vapor and a gas introduced from the outside. This is a discharge graft polymerization method characterized by supplying the mixture as a mixture and contacting the base material while circulating it.

Hereinafter, the discharge graft polymerization method will be explained using FIG. 1, a schematic diagram of the discharge graft polymerization apparatus manufactured by the present inventors for research on the discharge graft polymerization method, and the monomer The supply method will be explained in detail.

In Figure 1, 1, 2, 3, and 4 are a discharge activation chamber, a low pressure chamber, and
They are a monomer chamber and a monomer removal chamber, and the entrance and exit for the substrate in each chamber can be vacuum-sealed with the substrate passed through, so each chamber can maintain its own pressure.

The base material 17 fed out from the unwinding drum 13 in the discharge activation chamber 1 is exposed to discharge on the drive drum 14, and its surface is activated. The discharge occurs between the electrode 18 and the drive drum 1.
The active particles energetically excited during the discharge reach the surface of the substrate and activate the substrate. Note that the gas for starting and maintaining the discharge is supplied into the discharge activation chamber through the gas introduction hole 10. The pressure inside the discharge activation chamber is controlled by the amount of gas introduced and the amount of exhaust from the exhaust system 6, and is normally 0.01.
It is maintained from T0rr to 10T0rr. The power source for starting and sustaining the discharge is not particularly limited, and a direct current power source or an alternating current power source such as a low frequency, high frequency, or microwave power source can be used.

In addition to the internal electrode type electrodes shown in FIG. 1, external electrode type electrodes may also be used.

The base material 17 activated in the discharge activation chamber 1 is carried into the monomer chamber 3 through the low pressure chamber 2. The low pressure chamber is provided to prevent monomer from leaking from the monomer chamber 3 to the discharge activation chamber 1, and is connected to the discharge activation chamber 1 and the monomer chamber 3 through the exhaust system 7.
It is vented to lower pressure. In the monomer chamber 3, the base material 17 comes into contact with the monomer supplied from the monomer supply system 5, and the monomer graft-polymerizes onto the base material 17 using the active sites on the surface of the base material as graft polymerization initiation points. To go.

The base material graft-polymerized in the monomer chamber 3 is then carried into the monomer removal chamber 4, where unreacted monomers are vacuum desorbed by exhaust through the exhaust system 9, and the graft polymerization is completed. The present inventors tried a method of supplying the monomer into the monomer chamber 3 as a mixture of monomer vapor and a gas introduced from the outside, and supplying it to the activated base fabric while circulating it. Very favorable results were obtained in which the graft polymerized layer had a uniform thickness.

The method of mixing the monomer vapor with the gas introduced from the outside and the method of supplying and circulating the mixed vapor into the monomer chamber are not particularly limited, and the gist of the present invention is based on the monomer vapor alone. Instead of supplying the material to the fabric, a mixture of monomer vapor and an externally introduced gas is supplied to the base fabric.

To mix monomer vapor and gas introduced from the outside,
For example, it is possible to introduce gas into a monomer liquid and use the mixing of the gas and monomer vapor that occurs when the generated bubbles disappear on the liquid surface, or use ultrasonic vibration to generate a monomer vapor. Methods such as a method of mixing body vapor and a gas, or a method of mixing a monomer and a gas using ultrasonic vibration and diffusing the mixture can be used.

In addition, in order to supply and circulate a mixture of monomer vapor and gas introduced from the outside, for example, by evacuating the monomer chamber, the mixture of monomer vapor and gas is automatically supplied from the monomer supply system. can be supplied to the monomer chamber and circulated.

Hereinafter, one method of the monomer supply method of the present invention carried out by the present inventors will be explained in more detail based on the schematic diagram of FIG. 1, and the intention of the present invention will be clarified.

In the apparatus shown in FIG. 1, reference numeral 5 denotes a monomer supply system, into which monomer is supplied into the system through a monomer introduction hole 12.

Gas is introduced into the monomer liquid in the system through the gas introduction hole 11, and the introduced gas becomes bubbles and rises in the liquid.
When it disappears at the liquid interface, it mixes with the monomer vapor. The monomer vapor and gas thus mixed are supplied to the monomer chamber 3 through a valve that controls the supply amount. Since the monomer chamber 3 is evacuated through the exhaust system 8 , the mixture is automatically fed into the monomer chamber 3 and circulated to the substrate 17 and into the exhaust system 8 . The mixture discharged from the exhaust system 8 collects and recovers monomers in a cold trap 20. Although not shown, the mixture from the exhaust system 8 can also be automatically returned to the monomer supply system 5. The mixture supplied to the monomer chamber 3 was controlled by a valve for controlling the amount of gas introduced and the amount of supply, and an exhaust amount.

These amounts depend on the size of the apparatus, the area of the monomer liquid surface, the temperature of the monomer and the monomer chamber, and the vapor pressure of the monomer, so the amounts are determined according to each condition. 2mmH at room temperature
When using a monomer with a vapor pressure of more than 100 g, a graft polymerized layer of the desired thickness was obtained even when the monomer temperature and the temperature of the monomer chamber were at room temperature. The monomer, the monomer chamber, or the introduced gas may be heated in order to increase the saturated vapor pressure of the monomer or to supply latent heat of vaporization of the monomer.

In the conventional method, the saturated vapor pressure of the monomer is maintained near the monomer liquid interface in the monomer supply system, but in the monomer chamber 3, the saturated vapor pressure is below the saturated vapor pressure, and the monomer pressure ( concentration) distribution was occurring.

To prevent this, when the temperature of the monomer liquid was raised, the monomer condensed in the monomer chamber and onto the base fabric. In contrast, in the method of the present invention, the monomer chamber is maintained at a pressure close to the saturated vapor pressure by exhaust gas, so condensation of the monomer does not occur, and the mixed gas plays the role of a carrier gas. As a result, the monomer chamber is in a state close to saturated vapor pressure throughout the area,
No pressure distribution occurs. Another feature of the method of the present invention is that because the monomers circulate, a very large amount of monomers collide with the substrate per unit time. Furthermore, an excellent feature of the method of the present invention is that two or more types of monomers having different vapor pressures can be supplied to the substrate in any desired composition.

In the conventional method, the composition of the monomers was determined by the ratio of the vapor pressures of each monomer at the temperature of the monomer chamber 3, but in the method of the present invention, a plurality of monomer supply systems are provided and each monomer is By changing the temperature of the monomer liquid in the monomer supply system, the amount of gas introduced, and the amount of supply to the monomer chamber, a monomer mixture of any composition can be supplied to the base material, and the copolymerization ratio of the graft polymerization layer can be adjusted. can be changed. The gas introduced from the outside is Ar. N2, Ne
、． Any gas such as He may be used, but a gas that deactivates active sites like 02 is not preferred.

In particular, since the contamination of gases containing O2, such as O2 and air, has a very severe effect, it is necessary to eliminate even the slightest amount of oxygen contamination. In the method of the present invention, since the monomer chamber 3 is always evacuated, the monomer supply system 5 and the monomer chamber 3
This has the advantage of being able to eliminate air leaking into the air and preventing deactivation of active sites. Note that the description that the gas is introduced from the outside is to distinguish it from a trace amount of gas that remains in the monomer without being eliminated. As detailed above, in the present invention, when the monomer vapor is brought into contact with the activated base material, a gas is supplied from the outside and mixed with the monomer vapor, and the mixed vapor is discharged and mixed. Since the steam is circulated, the following excellent effects can be achieved.

First, as mentioned above, a graft polymer layer of uniform thickness is formed on the base material, and there are no various disadvantages associated with uneven thickness of the graft polymer layer seen in conventional methods.

Second, in this method, various types of monomers can be supplied in arbitrary compositions regardless of their vapor pressures, and a polymer having a specific copolymerization composition can be graft-polymerized.

Therefore, it has the excellent advantage of being able to form a graft polymer layer on the surface layer of the base material with characteristics that cannot be obtained by conventional methods. Third, surprisingly, compared to conventional methods, the method of the present invention allows for the formation of thicker graft polymerization layers, and no homopolymers are formed.

In conventional methods, for example, when electrical discharge graft polymerization is performed to improve the depth of color in fibers, the monomer condenses on the base fabric in the monomer chamber, resulting in an extremely high level of depth. However, when vacuum degassing is carried out in the winding chamber, a large amount of unreacted monomer is desorbed and the level of depth is reduced, and the index L value, which expresses the depth of color, is about 12. You can only get things. Further, when the graft polymerized fabric thus obtained is extracted with a solvent, a decrease in the grafting ratio is observed, and it is clear that homopolymerization occurs simultaneously with graft polymerization in the conventional method. On the other hand, in the method of the present invention, such a phenomenon was not observed, and an extremely high level of depth feeling with an L value of about 10 was obtained, and almost no homopolymer formation was observed. In general radical polymerization, the degree of polymerization is proportional to the monomer concentration. If this method is followed, a so-called thick graft polymerization layer should be formed with a higher degree of polymerization than that produced by the method of the present invention in the case of the conventional method in which condensation of monomers is seen on the base cloth. However, since such results were not obtained, it is thought that the dynamics of discharge graft polymerization are different from those of general radical polymerization. Hereinafter, the method of the present invention will be explained in more detail in Examples.

Note that the apparatus for carrying out the present invention is not limited to the apparatus schematically shown in FIG. 1, as a matter of course. Example 1 The dye on the surface of a polyester woven fabric dyed black was subjected to reduction decolorization treatment, washed with water, and air-dried.

The woven fabric was assembled into the apparatus shown in FIG. 1, and after all chambers in the apparatus were evacuated, the discharge activation chamber 1 was maintained at 1T0rr with Ar gas. In addition, the monomer supply system 5 has a sufficiently degassed 1.1ζ
3hydroperfluoropropyl acrylate (CH2=
At the same time, 4 cc/Mm of Ar gas was introduced from the gas introduction hole 11,
The monomer and the gas were mixed at the monomer interface and introduced into the monomer chamber 3. The monomer chamber 3 is evacuated little by little by the exhaust system 8, so that the introduced Ar gas does not cause the inside of the monomer chamber 3 to exceed the saturated vapor pressure of the monomer. The woven fabric is then continuously unwound from the unwinding roll 13 and exposed to an Ar gas discharge initiated and maintained on the drive drum 14 by a high voltage applied from the power source 19 to the electrode 18. The surface layer is activated. The activated woven fabric is introduced into the monomer chamber 3, where it is exposed to a mixture of the monomer and the introduced gas, and after a graft polymerization layer of the monomer is formed, the monomer is removed. The winding roll 16 is introduced into the chamber 4.
It was wound up and processing ended. As a result of measuring the index L value representing the depth of color of the woven fabric thus obtained, the values shown in Table 1 were obtained.

For comparison, the discharge treatment conditions were the same, and the monomer was supplied using the conventional heated steam supply method (monomer chamber temperature 40°C, monomer heating temperature 45°C). Similarly, L
The values were measured and the results shown in Table 1 were obtained. Note that the L value was measured using a digital colorimetric color difference calculator AUD-SCH-2 (Suga Test Instruments). As shown in Table 1, the method of the present invention has extremely little variation in the L value, that is, the depth of color.

This indicates that a graft polymer layer with an extremely uniform thickness was formed. On the other hand, in the conventional method, the variation in L value is large, and although the depth of color is improved, the depth of color is uneven and the product value is lost. Example 2 Using the same equipment as in Example 1, an undyed polyester woven fabric was activated by discharge under the same conditions, and then acrylic acid and N2 gas from the three monomer supply systems were mixed in the monomer chamber. mixture, a mixture of glycidyl methacrylate and N2 gas, and 1.
"・2,2'Tetrahydroperfluorohexyl acrylate (CH2-CHCOOC2H4C3F6CF3)
A mixture of N2 gas and N2 gas was mixed and brought into contact with the supplied mixture to graft-polymerize the copolymerized monomer.

Then, it was wound up in a monomer removal chamber to complete the treatment. Acrylic acid, glycidyl methacrylate, 1, 1', 2
- The amount of Ar gas, the temperature of the monomer supply system 5, and the temperature of the monomer chamber 3 are adjusted so that the mixing ratio of the vapor of 2' tetrahydroperfluorohexyl acrylate is 10 mol%, 30 mol%, and 60 mol%, respectively. The supply amount was adjusted. As a comparative example, a woven fabric activated under the same discharge conditions was graft-polymerized by being brought into contact with a mixed vapor generated by heating a monomer mixture at the above-mentioned mixing ratio to 60° C. in a monomer chamber.

The temperature of the monomer chamber was maintained at 56°C. Note that when the temperature of the monomer mixture was 60° C. or lower, the saturated vapor pressure of glycidyl methacrylate was insufficient, and a discharge graft polymerized fabric having the desired properties could not be obtained. Each of the discharge graft polymerized fabrics thus obtained was heat treated at 160° C. for 1 minute and then dyed black using a conventional method.

The L value of the woven fabric thus obtained is shown in Table 2. The woven fabric made by the method of the present invention is extremely uniform and has an extremely excellent depth of color, and has extremely high commercial value. It was hot.

From this, it is clear that the cloth subjected to discharge graft polymerization by the method of the present invention has a graft polymer layer having an extremely uniform thickness. In contrast, fabrics obtained by conventional methods had extremely large variations in L value and had completely lost their commercial value.

When three types of monomers are copolymerized and graft polymerized as in this example, the abrasion resistance of the graft polymer layer is improved and the level of commercial value is improved.

When rubbing was performed 300 times using a Gakushin type dyeing rub fastness tester, the L value of the discharge graft polymer fabric obtained in Example 1 increased from 11.0 to about 13.0. On the other hand, in the fabric of this example, there was only a slight change from 10.5 to 12.0, and no change was observed in the visual depth of color. Comparative Example The black-dyed polyester woven fabric used in Example 1 was assembled into the apparatus shown in FIG. 1, and all chambers in the apparatus were evacuated.

Next, a mixed gas of acrylic acid and argon gas generated by bubbling argon gas into the acrylic acid container cooled to 15° C. is introduced into the discharge activation chamber 1 through the gas introduction hole 10, and the inside of the chamber is maintained at 1T0rr. did. Other conditions were exactly the same as in Example 1, high voltage was applied, and 1,1',3 hydroperfluoropropyl acrylate was subjected to plasma polymerization on the woven fabric in the same manner as in Example 1. When the depth of color of the woven fabric thus obtained was measured, the results shown in Table 3 were obtained. As shown in the results in Table 3, the depth of color of the woven fabric obtained in this experiment was certainly improved, but the variation in L value in the length direction and width direction was extremely large.

This is thought to be because the acrylic acid monomer was introduced into the discharge activation chamber and the plasma polymerization of acrylic acid was non-uniformly deposited on the fabric due to the discharge. The biggest problem with plasma polymerization is that it requires forming a polymer film with a uniform thickness over a large area.
There is no example of applying a plasma polymerized film of uniform thickness to a large base material, and it seems impossible with current technology. Furthermore, when the treated cloth was rubbed, the depth of color was easily lost and it turned white.

The inventors previously reported 1-1! - Attempts have been made to improve the color depth of fibers by plasma polymerization of 3-hydroperfluoropropyl acrylate, but the depth of color was easily lost due to friction, so it was necessary to add the 7-component monomer to the fibers themselves. The graft polymerization method of the present invention has been studied. Judging from these facts, it seems that the reason why the color depth is lost due to friction in this experiment is that the plasma polymerized film of acrylic acid, the fluorine monomer, is peeled off from the fibers due to friction. In addition, in the treated fabric of Example 1, since the fluorine monomer was graft-polymerized to the fiber itself, the color depth was not drastically lost due to friction.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a discharge treatment apparatus for carrying out the method of the present invention. 1: Discharge activation chamber, 2: Low pressure chamber, 3: Monomer chamber, 4: Monomer removal chamber, 5: Monomer supply system, 6, 7, 8, 9: Vacuum exhaust system, 10, 11: Gas introduction 11-. 12: Monomer introduction hole, 13: Unwinding roll, 14, 15: Drive drum, 1
6: Winding roll, 17: Base material, 18: Discharge electrode, 1
9: High voltage power supply, 20: Cold trap, 21: Vacuum pump.

Claims (1)

[Claims] 1 In discharge graft polymerization (copolymerization), when the base material is activated by electric discharge and then brought into contact with the monomer to be grafted, the monomer is mixed with the monomer vapor and a gas introduced from the outside. A discharge graft polymerization method characterized in that the base material is brought into contact with the base material while being supplied and circulated.