KR101709339B1 - Method for manufacturing PVdF-PVC film increasing interfacial adhesive force by corona coupling treatment with alkyl methacrylate monomers - Google Patents

Abstract

Provided is a method for manufacturing a PVdF-PVC film, comprising the following steps: (a) modifying the surface of a PVdF film by performing corona discharge treatment in the presence of gas containing alkyl methacrylate monomers; and (b) forming a PVC coating layer on the upper surface of the PVdF film of which the surface is modified in the step (a). According to a method for manufacturing a PVdF-PVC film, after the surface energy is changed by coupling alkyl methacrylate monomers to the PVdF surface through corona discharge treatment, a PVdF-PVC film having excellent interfacial adhesive force and long term durability can be produced with a simple process of coating the PVC film.

Description

TECHNICAL FIELD [0001] The present invention relates to a PVdF-PVC film having improved interfacial adhesion by corona coupling treatment of alkyl methacrylate monomers,

The present invention relates to a process for producing a PVdF-PVC film having improved interfacial adhesion by processing a PVDF film by corona coupling treatment of an alkyl methacrylate monomer in the process of producing a PVDF-PVC film.

Polyvinyl chloride (PVC) is a widely used polymer for the production of color sheets and wrapping sheets for decoration or advertising. Since the PVC color sheet is also used as an exterior material for the outer wall of the building, the exterior of the PVC film is surface treated so as to exhibit weatherproof characteristics even for a long time.

Polyvinylidene fluoride (PVdF) is a material that can be used extensively as an external film for the surface treatment of PVC films, because it can withstand wind and rain for a long time and has a relatively low working temperature even among fluorinated polymers.

However, since PVC and PVdF films have a large surface property, they have poor interface durability due to poor interfacial adhesion between the two films. In order to compensate for these shortcomings, a primer adhesive is applied to the interface or a PVDF film layer A PVDF-PVC film was prepared by surface-treating the outer surface of a PVC film using a method of increasing the interfacial adhesion by adding about 50% of acryl-based resin such as acrylate.

However, when the method of applying the primer adhesive to the PVDF-PVC film interface is used as described above, there is a disadvantage that the manufacturing process is complicated and the manufacturing cost is increased because the lamination method for producing the multilayer film is used.

Further, when a method of adding an acrylic resin in advance to the PVDF layer or the like is used, there is a disadvantage that physical properties of the surface of the PVdF are deteriorated due to the excessive addition of acrylic because additional steps and cost for coating and drying the primer are required.

Therefore, there is a need for research on a method for producing a PVDF-PVC film excellent in interfacial adhesion and long-term durability through a simple manufacturing process so as to solve the above-mentioned disadvantages.

Korean Patent No. 10-0266942 (published on March 25, 1999) Korean Patent Publication No. 10-2014-0045996 (Publication date: April 4, 2014) Korean Patent Publication No. 10-2005-0000524 (published on 2005.01.05) Korean Patent Publication No. 10-2005-0108296 (published on November 16, 2005)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a PVDF film, The present invention is directed to a method for producing a PVDF-PVC film excellent in interfacial adhesion and long-term durability.

According to an aspect of the present invention, there is provided a method for manufacturing a PVdF film, comprising: (a) subjecting a surface of a PVdF film to a corona discharge treatment in a gas atmosphere containing an alkyl methacrylate monomer; And (b) forming a PVDF-PVC film on the surface of the PVdF film having the surface modified in the step (a).

In addition, the alkyl methacrylate monomer in the step (a) may include at least one selected from methyl methacrylate, ethyl methacrylate and butyl methacrylate.

In addition, the gas atmosphere of the step (a) is characterized by containing the alkyl methacrylate monomer in a concentration of 0.5 to 2%.

The corona discharge treatment in step (a) is performed at a discharge voltage of 4 to 7 kV.

The present invention also provides a PVdF-PVC film produced by the above-described method.

The PVdF-PVC film has an interfacial adhesive strength of 62% or more.

According to the method for producing a PVdF-PVC film according to the present invention, a simple process of coating a PVC film after the surface energy is changed by coupling an alkyl acrylate monomer to the PVdF surface through a corona discharge treatment, Excellent PVDF-PVC film can be produced.

In addition, it is possible to prevent air pollution caused by the volatile solvent generated in the conventional primer coating process, and a separate primer drying process is not required, so that the manufacturing time can be reduced and the cost reduction effect can be expected by reducing the length of the process line .

1 is a schematic view schematically showing the structure of a dielectric barrier corona generating device for corona discharge treatment of the surface of a PVDF film according to the present invention.
Fig. 2 shows the results of XPS analysis in which the atomic composition ratios of the PVDF films surface-treated by the methods according to Examples 1 to 3 and Comparative Example 1 were analyzed.
Fig. 3 is a graph showing the contact angle measurement results of PVDF films surface-treated by the methods according to Examples 1 to 3 and Comparative Example 1. Fig.
Fig. 4 shows the results of interfacial adhesion measurements of PVDF PVDF-PVC films prepared by the methods according to Examples 1 to 3 and Comparative Example 1. Fig.

Hereinafter, the present invention will be described in detail.

(A) corona discharge treatment in a gas atmosphere containing an alkyl methacrylate monomer to modify the surface of the PVdF film; And (b) forming a PVDF-PVC film on the surface of the PVdF film having the surface modified in the step (a).

In the step (a), the PVdF film is corona discharge treated to modify the surface of the PVdF film.

The PVdF film may utilize polyvinylidene fluoride (PVdF) materials of various known compositions, and PVDF films containing 30 to 50% of acrylic resin may be exemplified.

In this step, in order to perform the corona discharge treatment on the surface of the PVdF film, the PVdF film is subjected to corona discharge treatment in the gas atmosphere in which the alkyl methacrylate monomer is supplied to bind the alkyl methacrylate monomer to the surface of the PVdF film, The surface can be modified.

As described above, when the alkyl methacrylate monomer is bonded to the surface, the alkyl methacrylate monomer is fixed at the interface when the PVC coating layer is formed on the PVdF film to improve the interfacial adhesion between the PVdF and the PVC film .

More specifically, PVdF (30.3 mN / m) and PVC (41.5 mN / m) show a surface free energy difference of 11.2 mN / m, and the above alkyl methacrylate monomers have surface free energy , Thereby reducing the difference in the surface free energy of PVdF and PVC, thereby improving the interfacial adhesion.

For this purpose, the alkyl methacrylate monomer may be methyl methacrylate, ethyl methacrylate, butyl methacrylate or a mixture thereof, preferably ethyl methacrylate.

The corona discharge treatment may be performed in a gas atmosphere containing the alkyl methacrylate monomer at a concentration of 0.5 to 2%.

The corona discharge treatment may be performed at room temperature of atmospheric pressure, and corona discharge treatment may be performed using various types of corona discharge devices known in the art, and a dielectric barrier corona discharge device is a typical example.

For example, the present invention can be configured to perform a corona discharge treatment using a dielectric barrier corona discharge device as shown in FIG.

The dielectric barrier corona discharge device includes a gas supply compressor capable of continuously supplying gas to the reaction point of the PVdF film, a flow meter capable of measuring the flow rate of the supplied gas, A bubbler canister capable of supplying monomer gas, a discharge electrode in the form of a long blade for carrying out a dielectric barrier corona discharge, and a ground electrode coated with a silicone resin on a stainless steel bar to induce a corona discharge, The surface of the PVdF film is corona discharge treated by corona discharge treatment, and the alkyl methacrylate monomer molecules are bonded to the surface of the PVdF film by the corona discharge treatment to serve as a primer upon binding with PVC in a later step, Exhibit improved properties.

When the PVDF film is passed through the point where the corona discharge is induced by using the dielectric barrier corona discharge device as described above, the surface physical properties of the PVDF film are changed and the interfacial adhesion with the PVC coating layer coated on the PVDF film is improved At this time, the transfer speed of the PVdF film supplied to the discharge region of the corona discharge device may be adjusted to control the efficiency of the surface modification treatment of the PVdF film.

The corona discharge treatment is configured to be performed at a discharge voltage of 4 to 7 kV, more preferably at a discharge voltage of 4.8 to 5.4 kV to reduce the contact angle of the PVdF film to improve the interfacial adhesion of the PVdF film Can be configured.

Then, the conveying speed of the PVdF film supplied to the discharge region of the corona discharge device can be configured to be performed at a speed of 6 to 20 cm / sec.

The corona discharge treatment described above increases the concentration of oxygen on the surface of the PVdF film, shows a characteristic that the fluorine concentration is reduced, and the contact angle is reduced on the surface, so that the PVdF film exhibits excellent interfacial adhesion and the alkyl methacrylate monomer Molecules can be bonded to the PVdF film surface and easily adhere to the PVC film.

In the step (b), the PVC coating layer is formed on the upper surface of the PVdF film modified in the step (a). The PVC coating layer may be formed by various known solution coating methods, As a representative example, a method of forming a PVC coating layer by casting and curing a solution of a PVC mixed solution on the upper surface of a PVdF film is exemplified.

According to the method of manufacturing a PVdF-PVC film according to the present invention, a simple process of casting a PVC film after the surface energy is changed by coupling an alkyl acrylate monomer to the PVdF surface through a corona discharge treatment, And a PVDF-PVC film excellent in long-term durability can be produced.

In addition, it is possible to prevent air pollution caused by the volatile solvent generated in the conventional primer coating process, and a separate primer drying process is not required, so that the manufacturing time can be reduced and the cost reduction effect can be expected by reducing the length of the process line .

The PVdF-PVC film produced through the above-described method has a significantly improved interfacial adhesion strength compared to the 52% interfacial adhesion strength of conventional PVdF-PVC film due to the change in the surface of the PVdF due to the corona discharge treatment, It exhibits excellent interfacial adhesion and long-term durability, so PVdF-PVC film showing such characteristics can be effectively utilized in various fields.

Hereinafter, the present invention will be described in more detail with reference to examples.

The embodiments presented are only a concrete example of the present invention and are not intended to limit the scope of the present invention.

≪ Example 1 >

In order to corona the surface of the PVdF film, the PVdF film was transferred using a corona discharge device as shown in Fig. 1, and corona discharge was carried out under a gas atmosphere of methyl methacrylate monomer under the conditions shown in Table 1 to obtain PVdF The surface of the film was treated. For the corona discharge treatment, methyl methacrylate monomer vapor was fed through a bubble to the corona discharge point and the vapor pressure of approximately 10 hPa (7.6 torr) was maintained to maintain the concentration of methyl methacrylate (MMA) vapor at 1% And the air flow rate was maintained at 100 cm ³ / min.

A PVdF-PVC film was prepared by cast-coating a PVC film on the surface of the PVdF film surface-treated by the above method.

 Reaction pressure Atmospheric pressure  Reaction gas Methyl methacrylate monomer  Monomer concentration One %  Reaction temperature Room temperature  Discharge voltage 4.8 to 7.2 kV  Discharge frequency 5 to 40 kHz  Distance between electrodes 1.5 to 4.5 mm  dielectric Silicone resin 4 m / m  Winding speed 6 to 20 cm / sec

≪ Example 2 >

A PVdF-PVC film was prepared in the same manner as in Example 1, except that ethyl methacrylate (EMA) monomer vapor was used to corona discharge the PVdF film.

≪ Example 3 >

A PVdF-PVC film was prepared in the same manner as in Example 1, except that butyl methacrylate (BMA) monomer vapor was used to corona discharge the PVdF film.

≪ Comparative Example 1 &

A PVdF-PVC film was produced in the same manner as in Example 1, except that the PVdF film was not corona discharge treated.

<Experimental Example 1> Surface analysis of corona discharge treated film

(1) Analysis of atomic composition ratio of PVdF film surface

In order to analyze the surface characteristics of the corona discharge treated PVdF film, the atomic composition ratio of the surface of the corona discharge treated PVdF film was measured by X-ray photoelectron spectroscopy (XPS) The results of the analysis are shown in FIG.

As shown in FIG. 2, the surface of the PVdF film was subjected to corona discharge treatment in an atmosphere of butyl methacrylate monomers to increase the proportion of oxygen. As the discharge voltage increased from 4.8 kV, the atomic composition ratio of oxygen decreased from 8% to 14% Respectively.

On the other hand, the composition ratio of fluorine decreased from 39% to 30%. However, due to bonding with BMA molecules on the surface of the PVdF film, the atomic ratio of carbon slightly increased from 53% to 57%.

(2) Analysis of contact angle change of PVdF film surface

In order to analyze the surface characteristics of the corona discharge treated PVdF film, water was dropped on the corona discharge treated PVdF film and the PVdF film of Comparative Example 1 by the method according to Examples 1 to 3 using a contact angle meter The contact angle changes were analyzed and the results of the analysis are shown in FIG.

As shown in FIG. 3, in the case of the PVdF film subjected to the corona discharge treatment by the method according to Examples 1 to 3, the contact angle tended to decrease significantly as the corona discharge voltage was increased.

&Lt; Experimental Example 2 >

A cross-cut test (ASTM D3359) was conducted to analyze the interfacial adhesion of PVdF-PVC films prepared by the methods according to Examples 1 to 3 and Comparative Example 1, and the results of analysis are shown in FIG.

As shown in Fig. 4, the interfacial adhesion of the PVdF-PVC film of Comparative Example 1 without corona discharge treatment was 52%.

On the other hand, the interfacial adhesion of the PVdF-PVC film of Example 1 made of the corona-discharged PVdF film at a discharge voltage of 4.8 kV was 74%, the PVdF-PVC film of Example 2 was 95%, the PVdF- The PVC film exhibited an interfacial adhesion of 94%, indicating that the change in the PVdF surface by the corona discharge treatment contributed greatly to the adhesion to PVC. In particular, EMA monomers showed the best results.

However, the interfacial adhesion decreased when the discharge voltage increased, and the interfacial adhesion of the PVdF-PVC film made from the corona-discharged PVdF film at a discharge voltage of 7.2 kV was higher than that of the PVdF -PVC film. &Lt; tb &gt; &lt; TABLE &gt;

Therefore, it was confirmed that the excessive corona discharge treatment significantly reduced the surface energy of the PVdF film, thereby rather hindering the interfacial adhesion with the PVC film. In order to improve the PVdF-PVC interfacial adhesion, it is best to change the PVDF surface energy to a level similar to the surface energy of PVC, and a suitable material such as alkyl methacrylate with intermediate surface free energy is used between PVdF and PVC It is confirmed that the interfacial adhesion can be enhanced by acting as a primer when the alkyl methacrylate monomer molecules are bonded to the PVdF surface by the corona discharge treatment.

Claims (6)

(a) corona discharge treatment at a discharge voltage of 4 to 7 kV under a gas atmosphere containing an alkyl methacrylate monomer at a concentration of 0.5 to 2% to modify the surface of the PVdF film; And
(b) forming a PVC coating layer on the upper surface of the PVdF film having the surface modified in the step (a). The method according to claim 1,
Wherein the alkyl methacrylate monomer of step (a) comprises at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate and butyl methacrylate. delete delete A PVdF-PVC film produced by the method of any one of claims 1 and 2. 6. The method of claim 5,
A PVdF-PVC film characterized by an interfacial adhesion of at least 62% as analyzed using a cross-cut test (ASTM D3359).

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