KR20150085024A - Fluorinated resin film, method for producing same, and solar cell module - Google Patents

Abstract

Based resin having a polyvinylidene fluoride resin as a main component is extruded and formed by cooling at a cooling temperature set in the range of 85 to 120 DEG C and a temperature raising rate of 10 DEG C / Endothermic peak (intrinsic peak) inherent to the polyvinylidene fluoride resin in the range of 150 to 190 DEG C in the DSC curve obtained when heated from room temperature to 200 DEG C, and 1 A fluororesin film having at least one endothermic peak is disclosed.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fluororesin film, a method of manufacturing the same, and a solar cell module,

The present invention relates to a novel fluororesin film, a method of manufacturing the same, and a solar cell module provided with a solar cell backside protection sheet and the solar cell backside protection sheet formed using the fluorine resin film.

Fluorine-based resin films have been extensively used in fields requiring long-term durability due to their excellent weather resistance, heat resistance, stain resistance, chemical resistance and solvent resistance. In particular, a film made of a vinylidene fluoride resin as a main component takes advantage of the cost advantage of thinning, and as a surface protecting material, it has heretofore been used for internal and external members of buildings, chemical resistance, surface materials of containers requiring organic solvent resistance, Front and back face materials, fuel cell members, and the like. In addition, with the recent increase in demand of solar cell modules, solar cells are widely used as protective sheets (Patent Documents 1 and 2).

The demand for long-term durability for use as a protective sheet in such a solar cell is becoming stricter, and it is demanded to use it under harsh conditions and to prolong its service life. The applicant of the present invention has developed a technique for producing a vinylidene fluoride resin film having heat resistance, in particular, suppressed yellowing upon heating by controlling the crystal form of the vinylidene fluoride resin to a specific crystal form (Patent Document 3). That is, after the film is formed by extrusion molding and reheating is carried out at a temperature of 100 캜 or more, the I-form crystal structure (β-form) and the II-form crystal structure (α-form) obtained from the absorbance by the infrared absorption spectrum in the film The proportion of the type II crystal component when the total was 100 was controlled to be 90 to 100%, whereby a fluororesin film with less yellowing degree was obtained. However, it is desired to obtain a fluororesin film that further improves long-term durability according to the prolonged life of the product.

Japan Patent Publication No. 2011-129672 Japanese Patent Application Laid-Open No. 2008-28294 Japanese Patent Application Laid-Open No. 2006-273980

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a fluororesin film which has a longer durability than that of a conventional film, particularly a fluororesin modifier.

It is also an object of the present invention to provide a method of producing the fluororesin film, a solar cell backing sheet using the fluororesin film, and a solar cell module including the solar cell backing sheet.

In Patent Document 3, although the α-definition ratio obtained from the absorption intensity by the infrared absorption spectrum in the film is controlled to be high, when the α-definition ratio obtained by this method is increased to some extent, It was found that there was a case where it did not. As a result of studying an additional index to the crystal structure of the resin, the present inventors have found that the crystal structure difference, which can not be distinguished from the absorption intensity by the infrared absorption spectrum, can be measured by the heat flux differential scanning calorimetry By interpreting the DSC curve, it has been found that it is clearly identifiable. The inventors of the present invention have studied extensively to obtain a fluororesin film having a higher α ratio than that of the prior art by using this technique. As a result, it has been found that when the cooling temperature in extrusion molding is set in the range of 85 to 120 ° C., It has surprisingly been found that a fluorine resin film can be obtained which further improves yellowing resistance.

That is, according to one aspect of the present invention, a fluorine resin composition comprising a polyvinylidene fluoride resin as a main component is extruded and formed by cooling at a cooling temperature set in a range of 85 to 120 ° C, Endothermic peak inherent to the polyvinylidene fluoride resin in the range of 150 to 190 占 폚 in the DSC curve (first run) obtained by heating at room temperature to 200 占 폚 at a heating rate of 10 占 폚 / ) And at least one endothermic peak on the low-temperature side of the inherent peak.

The method of extrusion molding is not limited to a specific method as long as the cooling condition after resin extrusion has a significant effect on the crystallization of the resin. However, the method which the present inventors have studied in detail is a T-die molding method, Therefore, the T-die molding method is preferable. In the T-die molding method, the extruded resin is cooled by one or a plurality of cooling rolls, but the temperature in the first cooling roll for initially cooling the extruded resin is the cooling temperature in the present invention, Lt; / RTI >

When a film is formed by extruding a fluorine resin composition containing a polyvinylidene fluoride resin as a main component by setting the cooling temperature at the time of extrusion molding at 85 to 120 DEG C and forming the film, (Inherent peak) inherent to the polyvinylidene fluoride resin is present in the range of 150 to 190 DEG C in a DSC curve obtained by differential scanning calorimetry and at least one endothermic peak A new film having a peak is obtained.

The film is also a film having an? Fixed ratio determined by the following formula (1) of 80% or more.

Further, in the above-mentioned fluororesin film, the fluororesin composition may contain any resin, additive or the like which is generally contained in the fluororesin, as long as it is a resin composition comprising a polyvinylidene fluoride resin as a main component. Means that the polyvinylidene fluoride resin is contained in the resin composition in an amount of 50% by weight or more, preferably 60% by weight or more, as the resin component, and the polyvinylidene fluoride resin is contained in the poly In the case of only vinylidene fluoride series, that is, the polyvinylidene fluoride resin is 100% by weight. Therefore, in one embodiment of the present invention, the fluororesin composition contains only polyvinylidene fluoride as a resin component. In another embodiment of the present invention, a polymethyl methacrylate resin having excellent compatibility with a polyvinylidene fluoride resin is blended and mixed and extrusion-molded. For example, the resin composition to be extruded may contain 50 to 95% by weight, preferably 60 to 95% by weight, and 5 to 50% by weight, preferably 5 to 40% by weight, of polyvinylidene fluoride resin By weight.

Further, in the fluororesin film, the fluororesin composition may contain various additives in addition to the resin component, but it is particularly preferable to contain titanium oxide or an ultraviolet absorber for the purpose of shielding ultraviolet rays. Here, titanium oxide is added in an amount of 5 to 40 parts by weight based on 100 parts by weight of the resin composition, and the ultraviolet absorbent is added in an amount of 0.1 to 5 parts by weight, preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the resin composition.

It is preferable that the film thickness of the fluororesin film is in the range of 10 to 50 mu m.

According to another aspect of the present invention, there is provided a process for producing a film, comprising the steps of extruding a molten resin comprising a fluorine-based resin composition comprising a polyvinylidene fluoride resin as a main component into a film, And a cooling roll set at such a cooling temperature. The DSC curve obtained by heating at room temperature to 200 占 폚 at a temperature raising rate of 10 占 폚 / minute by a heat flow differential scanning calorimetry based resin film having an endothermic peak (intrinsic peak) inherent to polyvinylidene fluoride resin in the range of 150 to 190 DEG C in the first run and one or more endothermic peaks on the low-temperature side of the intrinsic peak Method is provided.

Also in such a production method, the fluorocarbon resin film to be produced has an? Fixed ratio determined by the formula (1) of not less than 80%. In a preferred embodiment of the fluorine resin composition, 50 to 95% by weight, preferably 60 to 95% by weight, of a polyvinylidene fluoride resin and 5 to 50% by weight, preferably 5 to 40% by weight, By weight. The fluorine resin composition preferably contains 5 to 40 parts by weight of titanium oxide or 0.1 to 5 parts by weight of an ultraviolet absorber, based on 100 parts by weight of the total of the resin components. It is preferable that the film thickness of the fluororesin film is in the range of 10 to 50 mu m.

According to still another aspect of the present invention, there is provided a solar cell module formed by using a solar cell backing sheet formed by the fluorine resin film and a solar cell backing sheet.

INDUSTRIAL APPLICABILITY The fluororesin film according to the present invention is excellent in weather resistance, heat resistance, stain resistance, chemical resistance, solvent resistance, mechanical properties and secondary processability, and has excellent heat resistance Since it is a resin film having a specific peak pattern in the flow velocity differential scanning calorimetry method, it has excellent long-term durability, particularly denitrification resistance. In addition, the solar cell backing sheet and the solar cell module formed using the fluororesin film according to the present invention are also excellent in long-term durability, in particular, in swelling resistance.

Fig. 1 is a graph showing the relationship between the heat flow rate of the fluorine resin film formed in Example 1 (cooling roll temperature: 85 占 폚), Example 2 (cooling roll temperature: 100 占 폚) and Example 3 Fig. 6 is a graph showing the DSC curve obtained by differential scanning calorimetry. Fig.
2 is a graph plotting the? Correction ratio determined by infrared absorption spectrum analysis and the? B value obtained in the anti-moisture heat test with respect to the cooling temperature of the cooling roll in the T-die molding. . The films prepared by changing the cooling temperature to 45 to 75 占 폚 were Comparative Examples 3 to 6, and the films produced by changing the cooling temperature to 85 to 120 占 폚 were Examples 11 to 14.
Fig. 3 is a spectrum chart showing the results of infrared absorption spectrum analysis performed on a film produced from a fluorine resin containing various polymethyl methacrylate resins in various contents. Fig. The films prepared by changing the proportion of the methyl polymethacrylate resin in the resin composition to 0 to 50% by weight were Examples 15 to 19, and the films produced by changing the same ratio to 60 to 70% 8.
4 is a graph showing the results of X-ray diffraction performed on the films of Examples 15 to 19 and Comparative Examples 7 to 8.
Fig. 5 is a graph showing the DSC analysis results of the films of Examples 15 to 19 and Comparative Examples 7 to 8. Fig.

Hereinafter, embodiments of the present invention will be described in detail.

The fluororesin film according to one embodiment of the present invention is formed by extrusion molding from a fluororesin composition containing a polyvinylidene fluoride resin as a main component.

≪ Fluorine-based resin composition >

The fluororesin composition may contain any resin or additive generally contained in the fluororesin, as long as it is a resin composition comprising a polyvinylidene fluoride resin as a main component. Means that the polyvinylidene fluoride resin is contained in the resin composition in an amount of 50% by weight or more, preferably 60% by weight or more, as the resin component, and the polyvinylidene fluoride resin is contained in the poly In the case of only vinylidene fluoride series, that is, the polyvinylidene fluoride resin is 100% by weight.

The term " polyvinylidene fluoride resin " refers to a crystalline resin showing various crystal structures such as?,?, And? Types, and contains vinylidene fluoride monomer as a main component and vinylidene fluoride homopolymer or vinyl fluoride Quot; refers to a copolymer of lidene and a copolymerizable monomer. Examples of the copolymer include vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer and the like. A homopolymer of vinylidene fluoride is preferably used.

The fluorine resin composition may contain a resin component other than the polyvinylidene fluoride resin. Such a resin component is excellent in compatibility with the vinylidene fluoride resin and improves workability by lowering the extrusion temperature during film extrusion molding, A methacrylic ester-based resin is preferable in order to exhibit such effects as improving adhesiveness when laminated with another material. Here, the methacrylic ester-based resin may contain, in addition to the methyl methacrylate homopolymer (polymethacrylate methyl), a methacrylate methyl monomer in a predetermined amount, for example, 50 mol% or more and an acrylic ester or methyl methacrylate , A copolymer containing a predetermined amount, for example, less than 50 mol% of methacrylic ester other than methacrylic acid, and a mixture of two or more of these polymers. Examples of the acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and the like, and methacrylic acid esters other than methyl methacrylate include ethyl methacrylate and propyl methacrylate. The copolymer is not limited to a random copolymer. For example, a graft copolymer or the like is also used, and graft polymerization of a monomer mainly composed of methyl methacrylate to an acrylic saturated crosslinked rubber is preferably used. A particularly preferable methacrylic acid ester resin is a polymethyl methacrylate resin.

Accordingly, in one example, the fluororesin composition contains only polyvinylidene fluoride as a resin component. In another example, the fluororesin composition contains a polyvinylidene fluoride resin and a polymethyl methacrylate resin as resin components. In the latter case, as long as the polyvinylidene fluoride resin is the main component, the content of the polymethyl methacrylate resin is arbitrary. In a preferred embodiment, the fluororesin resin composition contains 50 to 95% by weight of polyvinylidene fluoride resin, 60 to 95% by weight, and a polymethyl methacrylate resin in an amount of 5 to 50% by weight, preferably 5 to 40% by weight.

It is preferable that the fluorine resin composition contains at least one of a pigment and an ultraviolet absorber in order to impart an ultraviolet shielding effect. For example, when the film is intended to protect the base substrate, there may be a case where no pigment is added. In this case, however, an ultraviolet absorber is added. This is because when the film is used without adding a pigment, the ultraviolet ray reaches various substrates and the like, so that the vinylidene fluoride resin film does not deteriorate, and adhesives and the like used for lamination with various substrates and substrates are deteriorated There is a possibility that a problem of peeling off from the polyvinylidene fluoride resin film may occur.

The pigment to be used is not particularly limited and may be an inorganic pigment, an organic pigment, a pearl pigment or the like. In view of weather resistance, an inorganic pigment of an oxide or a composite oxide is suitably used, and titanium oxide is particularly preferable. The amount of the pigment, particularly titanium oxide, is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the resin. When the addition amount is less than 5 parts by weight, the film can not be homogeneously dispersed in the film, and partial unevenness may occur. On the other hand, when it is added in an amount exceeding 40 parts by weight, the dispersibility of the fluorine-based resin to the fluorine-containing resin is remarkably lowered to cause appearance defects.

The ultraviolet absorber may be any one which is compatible with the vinylidene fluoride resin. Examples of the ultraviolet absorber include benzotriazole-based, oxalic acid-based, benzophenone-based, hindered amine-based and others. Preferably, a high molecular weight type ultraviolet absorber having a molecular weight of 300 or more is suitably used in order to minimize volatilization when used as a film and as a film. The amount of the ultraviolet absorber to be added is 0.1 to 5 parts by weight, preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the resin.

The film of the present invention may contain additives such as a stabilizer, a dispersant, an antioxidant, a chlorine scouring agent, a surfactant, an antistatic agent, a filler such as silica and alumina, a fluorine surface modifier, It is also possible to add various additives such as a dispersant and the like in a range in which their dispersibility is not impaired.

As a method of mixing a pigment, an ultraviolet absorber and various other additives into the film of the present invention, a method in which a resin and an additive are mixed in advance and melt-kneaded using a commonly used single-screw extruder can be employed. Furthermore, by employing a method of pre-mixing the mixture in advance at a high temperature by using a twin-screw extruder of high-kneading type or using a high-speed rotary mixer, and then melt-kneading the mixture by a single-screw extruder, This excellent film can be obtained.

The film thickness of the fluororesin film of the present invention is preferably 50 占 퐉 or less, more preferably 10 to 30 占 퐉. If it is less than 10 mu m, the handling property is significantly lowered, and sufficient durability may not be obtained. On the other hand, if it exceeds 50 탆, the cost of the material, such as an increase in the cost, becomes disadvantageous. It is also possible to use a film of the present invention as a surface layer and an acrylic resin layer as a backing layer or a blend of a vinylidene fluoride resin and an acrylic resin to form a film of two or more layers.

≪ Production of fluororesin film &

The fluororesin film can be generally extruded by a film forming method using a T-die or a film forming method using inflation dies. In the present invention, a film forming method using a T-die is suitably employed. The extrusion conditions are not particularly limited and the conditions conventionally used for forming the vinylidene fluoride resin film can be used. In the present invention, the cooling temperature after extrusion is 85 to 120 DEG C, preferably 90 to 120 DEG C, More preferably in the range of 100 to 120 占 폚. That is, when a film is formed using a T-die molding machine, the high temperature resin extruded from the T-shaped die is cooled and solidified by a metal cooling roll disposed under the T-shaped dies, but the temperature of the metal cooling roll is 85 to 120 DEG C , Preferably 90 to 120 ° C, and more preferably 100 to 120 ° C. When a plurality of cooling rolls are disposed in the extrusion molding machine, the temperature of the first cooling roll (first cooling roll) is 85 to 120 DEG C, preferably 90 to 120 DEG C, more preferably 100 to 120 DEG C Lt; / RTI > It is customary that the metal cooling roll and the rubber roll are disposed to face each other under the T-shaped dies, but the use of the rubber roll and the set temperature of the rubber roll are arbitrary. When the cooling temperature is set to less than 85 캜, a film having a desired long-term durability, particularly a vulcanization resistance, can not be obtained. On the other hand, if the cooling temperature is set to be higher than 120 ° C, the film can not be formed well due to the peeling failure in the roll.

The raw material may be supplied by a resin composition prepared by preliminarily melt-kneading each raw material. However, the individual raw materials are directly supplied to a single shaft or a twin-screw extruder, melted at a temperature of usually 150 to 260 ° C, So that the film can be formed by extrusion.

≪ Fluorine-based resin film &

The fluorine resin film extruded from the above-mentioned fluorine resin composition under the above-mentioned conditions is a film having an? Correction ratio determined by the above formula (1) of not less than 80%, but the? If the value is exceeded, the film becomes saturated and does not reflect the crystal structure change of the film. However, this state change can be grasped by analysis using a heat flow differential scanning calorimetry method. That is, in the fluorine resin film, regardless of whether the cooling temperature is set in the range of 85 to 120 占 폚, the DSC curve obtained by heating at room temperature to 200 占 폚 at a heating rate of 10 占 폚 / minute by the heat flow differential scanning calorimetry an endothermic peak inherent to the polyvinylidene fluoride resin is observed at about 170 DEG C in the first run. However, the fluorinated resin film according to the present invention, which is formed by setting the cooling temperature in the range of 85 to 120 占 폚, has an endothermic peak derived from at least one? -Phase on the low temperature side of the endothermic peak inherent to the polyvinylidene fluoride resin The temperature is visible. The higher the endothermic peak on the low temperature side becomes, the more the? Definition ratio increases and the long term durability of the film, particularly the vulcanization resistance, is improved. For example, in the fluororesin film according to the present invention, the color b value immediately after the film production is about -2.5 to -0.5, but there is no significant yellowing even after the humidity and heat resistance test described later, and the Δb value before and after the test is 2 Or less.

In the fluorine resin film formed under the conditions of the present invention, the endothermic peak appearing on the low temperature side of the endothermic peak inherent to the polyvinylidene fluoride resin is always derived from? , There is a case where an endothermic peak is seen on the low temperature side of the endothermic peak inherent to the polyvinylidene fluoride resin in some cases when the film is formed under conditions other than the conditions of the present invention. However, such an endothermic peak is not an endothermic peak derived from an anisotropy but an endothermic peak derived from a beta -start, which can be confirmed by, for example, an X-ray diffraction method. Therefore, the fluorine resin film exhibiting the desired DSC curve formed under the conditions within the scope of the present invention has excellent weather resistance, in particular, yellowing resistance, as compared with the fluorine resin film formed under the conditions outside the scope of the present invention.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. Methods for evaluating the characteristics of each sample of the raw material and the film used in the examples are as follows.

<Materials Used>

A polyvinylidene fluoride resin having a fluorine content of about 59% and a melting point of about 170 ° C, MFR (condition: 230 ° C, weight of 3.8 kg) 29 (g / 10 min)

Methacrylic acid ester resin: a methacrylic ester resin containing a rubber component of Acryphet IR-S404 (manufactured by Mitsubishi Rayon Co.), butyl acrylate (n-BA) and butyl methacrylate (BMA), MFR (Condition: 230 DEG C, 37.3 N) 7.8 (g / 10 min)

Titanium oxide: Tai-Pure R960 (manufactured by DuPont), (particle diameter: about 0.35 占 퐉, pure titanium powder: about 89%)

<Evaluation method>

(1)? Positive ratio

And the infrared absorption spectrum was measured by NICOLET380 FT-IR (manufactured by Thermo Fisher Scientific). The characteristic absorption of the? -Form crystal of the polyvinylidene fluoride resin in the infrared absorption spectrum is at a wave number of 840 cm ^-1 and the characteristic absorption of the? -Type crystal exists at a wavenumber of 765 cm ^-1 . From the respective peak intensities of the obtained spectra, the? Correction ratio was calculated using the following formula (1) (Tomoda Hanada, Minoru Ando, "Polyfluorinated polyvinylidene fluoride and polyvinyl acetate and polyethyl methacrylate blend system Crystallization of vinylidene &quot;, Journal of Tokyo Institute of Home Economics, July 1992, No. 32, page 5-12).

(2) Color after humidity and humidity test

The humidity resistance thermostability test was conducted using a pressure cooker SPY-4016 (manufactured by Arp) as a testing machine. A color sample of the EVA and the EVA was subjected to colorimetric measurement using a colorimetric colorimeter ZE-2000 manufactured by NIPPON KOMAKU INDUSTRIES CO., LTD., And the EVA and the EVA were placed in a tester to perform an endurance test under the following conditions.

Temperature: 125 ° C

Humidity: 100%

Pressure: 2.3 atm

Time: 50hr

After the test, the chrominance of the surface of the film adhered to the EVA was measured again, and the value of? B before and after the test was calculated. The evaluation criterion is that the Δb value is less than 2 and the yellow color is less.

(3) UV transmittance

The UV transmittance at a wavelength of 340 nm was measured using a Hitachi spectrophotometer U-3310 (manufactured by Hitachi High-Tech Fielding Co., Ltd.).

(4) Heat flow differential scanning calorimetry

The measurement was carried out under the following conditions using a differential scanning calorimeter DSC3100SA (Bruker, AXS).

Temperature: Room temperature 200 ° C

Heating rate: 10 ° C / min

Sample mass: 1.5 mg

(5) X-ray diffraction

The measurement was carried out under the following conditions using an X-ray diffraction apparatus Ultima IV (Rigakusa).

X-ray source: Cu sealing pipe

Applied voltage / current: 40kV / 40mA

Detector: High-speed detector D / teX Ultra

&Lt; Examples 1 to 10 and Comparative Examples 1 and 2 >

The vinylidene fluoride resin, the polymethyl methacrylate resin, and the titanium oxide were mixed so that the PMMA ratio shown in Table 1 (the weight of the polymethyl methacrylate resin to the total of 100 wt% of the vinylidene fluoride resin and the polymethyl methacrylate resin %), and and adjusted to parts by weight) of titanium oxide on the titanium quantity (resin 100 parts by weight of the oxide and extruded through a T-die at an extrusion temperature of 240 ℃ from after kneading committed to φ 65mm single-screw extruder, the same extruder, the table 1 to obtain a film relating to Examples 1 to 10 and Comparative Examples 1 and 2 having a thickness shown in Table 1. The results are shown in Table 1 below.

The prepared film was evaluated for the? Correction ratio, the color after the heat and humidity resistance test, the UV transmittance, and the thermal flow intermittent scanning thermal calorie according to the evaluation method described above. The results are shown together in Table 1. 1 shows DSC curves obtained by measurement of heat flow rate differential scanning calorimetry for the films according to representative examples 1 to 3. Further, in Comparative Example 2, the film could not be smoothly peeled off from the cooling roll, and a film that could be provided for the evaluation of characteristics could not be produced.

From the results shown in Table 1, it can be seen that the films according to Examples 1 to 10 have an endothermic peak on the low temperature side of the intrinsic peak and a sufficiently small value of the color difference? B after the heat and humidity resistance test in addition to a high? Able to know. On the other hand, in Comparative Example 1, it was found that the? Correction ratio was low and the vulcanization resistance deteriorated. In addition, in Comparative Example 1, an endothermic peak was also observed, but this peak was found to be a peak originating from the beta crystal by X-ray diffraction. From the results shown in Fig. 1, the endothermic peaks of the inherent peaks of the polyvinylidene fluoride resin in the fluorine resin films of Examples 1 to 3 are seen, and as the temperature of the cooling roll becomes higher, the endothermic peaks thereof And it was found that it became remarkable.

&Lt; Examples 11 to 14 and Comparative Examples 3 to 6 >

In order to investigate the influence of the set temperature of the metal cooling roll against the yellowing of the film, the PMMA ratio was 25% and the amount of titanium oxide was 22 parts by weight, and the set cooling temperatures of the metal cooling rolls were 45 ° C, 55 ° C, C, 85 deg. C, 100 deg. C, 110 deg. C and 120 deg. C to prepare fluorinated resin films according to Comparative Examples 3 to 6 and Examples 11 to 14. The? -Fix ratio was obtained for the obtained film and the? B value was measured. The results are shown in Fig.

2, when the cooling temperature is low, the? Correction ratio is low, and as a result, the yellowing phenomenon becomes remarkable. However, when the cooling temperature is raised to 80 占 폚, the? Correction ratio increases and the yellowing phenomenon is not sufficiently reduced However, it can be seen that it is gradually reduced. However, when the cooling temperature reaches about 85 占 폚, the? Positive ratio reaches the saturated state and does not further increase, but the yellowing phenomenon gradually decreases gradually. That is, it is understood from this experimental result that there is a limit to the method of reducing the yellowing phenomenon based on the analysis by the? Positive ratio based on the infrared absorption spectrum analysis.

&Lt; Examples 15 to 19, Comparative Examples 7 to 8 >

In order to investigate the effect of the PMMA ratio on the crystal structure of the fluorine resin film, the setting temperature of the metal cooling roll was set to 85 캜 and the amount of titanium oxide was set to 22 parts by weight, and the PMMA ratio was changed from 0 wt% to 10 wt% , 30% by weight, 40% by weight, 50% by weight, 60% by weight and 70% by weight, respectively, to prepare fluorinated resin films relating to Examples 15 to 19 and Comparative Examples 7 to 8. The crystal structure of the obtained fluororesin film was analyzed by an infrared absorption spectrum method, an X-ray diffraction method, and a heat flux differential scanning calorimetry method. The results are shown in Figs. From the results of the analysis by the infrared absorption spectrum method of Fig. 3, it can be seen that the peaks derived from the? -Channel and the? -Channel decrease with the increase of the PMMA ratio. From the analysis results by the X-ray diffraction method in Fig. 4, it can be seen that when the PMMA ratio exceeds 50 wt%, the crystallization of PVDF is inhibited. From the analysis results by the heat flow differential scanning calorimetry method of FIG. 5, it can be seen that as the PMMA ratio increases, the melting point Tm gradually decreases from about 170 占 폚 (PMMA ratio: 0 weight%). On the other hand, when the PMMA ratio exceeds 50% by weight, the intrinsic endothermic peak intensity becomes weak, and it can be seen that PVDF and PMMA are commonly used.

Claims (8)

Based resin composition comprising a polyvinylidene fluoride resin as a main component is extruded and formed by cooling at a cooling temperature set in the range of 85 to 120 DEG C and is formed by heat flow rate differential scanning calorimetry (Inherent peak) inherent to the polyvinylidene fluoride resin in the range of 150 to 190 DEG C in a DSC curve (first run) obtained when the resin composition is heated from room temperature to 200 DEG C at a heating rate of 50 DEG C / minute, And one or more endothermic peaks on the low temperature side of the peak. The method according to claim 1,

Wherein the? -Fix ratio determined by the formula (1) is 80% or more. The method according to claim 1 or 2,
A fluororesin film comprising a polyvinylidene fluoride resin having a fluororesin content of 50 to 95% by weight and a methyl polymethacrylate resin having 5 to 50% by weight as a resin component. The method of claim 3,
Wherein the fluorine resin composition contains 5 to 40 parts by weight of titanium oxide or 0.1 to 5 parts by weight of ultraviolet absorber with respect to 100 parts by weight of the total of resin components. The method according to any one of claims 1 to 4,
Wherein the film thickness is within a range of 10 to 50 mu m. Based resin composition comprising a polyvinylidene fluoride resin as a main component; and a step of cooling the extruded film-like resin at a cooling temperature in the range of 85 to 120 ° C , A specific heat resistance value of the polyvinylidene fluoride resin which is in the range of 150 to 190 DEG C in a DSC curve (first run) obtained when heated from room temperature to 200 DEG C at a heating rate of 10 DEG C / minute by a heat flow differential scanning calorimetry A method of producing a fluororesin film having an endothermic peak (intrinsic peak) and at least one endothermic peak on the low temperature side of the intrinsic peak. A protective sheet for solar cell back surface formed by the fluorine resin film according to any one of claims 1 to 5. A solar cell module formed using the solar cell backing sheet according to claim 7.

Images