WO2016143548A1 - Vinylidene-fluoride-based resin composition, molded resin object, resin film, and protective sheet - Google Patents

Abstract

The present invention addresses the problem of providing a vinylidene-fluoride-based resin composition, a molded resin object, a resin film, and a protective sheet which each retain various properties inherent in vinylidene-fluoride-based resins and change little in anisotropy with the lapse of time. The vinylidene-fluoride-based resin composition according to the present invention comprises a vinylidene-fluoride-based resin, a colorant, and a finely powdered tetrafluoroethylene-based resin as a crystal nucleator.

Description

Vinylidene fluoride resin composition, resin molded body, resin film, and protective sheet

The present invention relates to a vinylidene fluoride resin composition comprising a vinylidene fluoride resin, a colorant, and a finely divided tetrafluoroethylene resin as a crystal nucleating agent, and a resin molded article formed from the resin composition The present invention relates to a resin film and a protective sheet obtained from the resin film.

Vinylidene fluoride resin (hereinafter sometimes abbreviated as “PVDF”) is excellent in weather resistance, chemical resistance, abrasion resistance, electrical properties, crystallinity, and excellent moldability. It is manufactured as a molded body such as a film or a sheet, and is used as a protective sheet for various members and equipment by taking advantage of wear resistance and weather resistance.

A resin molded body formed by including PVDF, for example, a resin film, an unstretched film or a stretched film is used depending on the application. Among them, the unstretched film is more flexible than the stretched film, and the elongation is also high. In recent years, the use as a back sheet for a solar cell module has increased.

An unstretched film is manufactured through cooling after the polymer is extruded in a molten state, so that molecular structures such as molecular chains and crystals are affected by the take-up direction (winding direction, machine direction). May be fixed. In such a case, depending on the degree of the influence of the molecular structure, mechanical property values such as strength and elongation differ in the MD direction (Machine Direction) and the TD direction (Transverse Direction) (hereinafter referred to as the width direction). , Which may be abbreviated as “anisotropy of mechanical property values” or “anisotropy”), and has been conventionally studied to reduce the degree of anisotropy when producing an unstretched film. Has been earnestly advanced.

Furthermore, the unstretched film is likely to change in the molecular structure fixed in the film over time, and as a result, the anisotropy may change (that is, the anisotropy increases). This problem of anisotropy with time, in particular, controls the quality of PVDF film after shipping, designs the performance of products using PVDF film, and ensures the reliability of the product life. Above, it is a big problem. Moreover, when using for a solar cell module backsheet etc., a large amount of coloring agents (titanium oxide etc.) are often used, and the influence on anisotropy is also a concern.

Against this backdrop, recently, there is a great demand from the market for high-performance resin molded products such as PVDF films, and problems such as anisotropy and aging of the products are produced. There is a strong demand for solutions and improvements.

Based on the technology related to crystal nucleating agents, the present inventors have recognized that anisotropy and anisotropy change with time in manufacturing the above products are related to the state of microcrystals. From the above, the following two patent documents were found as known techniques, and the following considerations were made.

International Publication No. WO2010 / 122936 (Patent Document 1) describes a white resin film containing titanium oxide as a colorant formed from a vinylidene fluoride resin composition containing polymethyl methacrylate. There is a description of a crystal nucleating agent as a general description of the product. However, the substance name and content of the crystal nucleating agent are not specifically described.

On the other hand, tetrafluoroethylene-based resin (hereinafter sometimes abbreviated as “PTFE”) powder is known to work as an internal mold release agent, lubricant or flame retardant (anti-dripping agent) as a synthetic resin additive. It has been. Japanese Patent Application Laid-Open No. 7-304925 (Patent Document 2) describes that 5% by weight or more of calcined PTFE powder is added to a thermoplastic or thermosetting resin to obtain a molding material for a sliding member. . However, here, PVDF is not described as the resin, and the calcined PTFE powder has a relatively large average particle size of 5 to 60 μm. After all, Patent Document 2 does not describe anything about using finely powdered PTFE as a crystal nucleating agent in PVDF.

International Publication No. 2010/122936 Japanese Patent Laid-Open No. 7-304925

An object of the present invention is to contain a colorant and maintain the properties as PVDF, while the resin molded body has a small anisotropy, and the anisotropy hardly changes over time (hereinafter simply referred to as “anisotropic”). Is sometimes abbreviated as “small change with time”.) To provide a PVDF composition.

Another object of the present invention is to provide a PVDF resin molded article containing a colorant and having a small anisotropic change over time, in particular, a PVDF resin film, and a protective sheet using the same, and a solar cell module To provide a backsheet.

PVDF is originally a resin that has a low crystallization temperature and is likely to form microcrystals. In particular, unstretched films include entangled amorphous and intramolecular or intermolecular microcrystals, It is considered that some degree of amorphous orientation and microcrystalline deformation are caused by the external force in the MD direction during film formation.

Furthermore, such microcrystals are often non-uniform in structure, size, etc., and are therefore susceptible to changes over time despite being crystal parts.
Therefore, in particular, in order to prevent the change of anisotropy over time, that is, to suppress the expression of anisotropy, the deformation of the microcrystal is not caused and the amorphous is not easily oriented. This is very important.

By controlling the structure and shape of the microcrystals, the present inventors suppress the deformation of the microcrystals over time and develop the function of suppressing the amorphous orientation, thereby causing the problem of anisotropy over time. I thought that it would be possible to solve (no change in anisotropy).

In other words, when the polymer is cooled from the molten state and solidified, it is considered that the formation of high-density and fine crystallites at a high concentration and high uniformity is the key to prevent anisotropy change over time. It was.

For this purpose, it is important to start the formation of microcrystals at an early stage when cooling. The formation and growth of microcrystals may be caused by factors such as crystallization temperature, crystal nuclei and crystal nucleating agent, crystal nucleation rate, crystal growth rate, and cooling conditions.
Among these factors, the present inventors have continued earnestly researching whether the problem of anisotropy with time can be solved by pursuing a crystal nucleating agent and its effect.

The present inventors have studied crystal nucleating agents (nucleating agent components, particle size, mixing amount, etc.) that influence microcrystal formation, and by blending a specific component crystal nucleating agent with PVDF, preferably into PVDF. It has been found that target microcrystals are formed by blending a specific amount of a specific component and a crystal nucleating agent having a specific particle size.

The inventors first attempted to use boron nitride as a representative of well-known crystal nucleating agents for inorganic compounds. In this case, the base composition may be abbreviated as a methacrylate resin (for example, polymethyl methacrylate (hereinafter referred to as “PMMA”), which is known to have good compatibility with PVDF in order to improve adhesion. .)) And PVDF, and a composition blended with titanium oxide as a colorant was used.

However, when boron nitride is used as a crystal nucleating agent for PVDF (including PMMA), the DSC curve at lower temperature (see FIG. 1) shows a slight crystallization compared to the case where no crystal nucleating agent is added. Although the temperature (peak) moved to the high temperature side, it was confirmed that there was almost no effect as a crystal nucleating agent.

This result is presumably because the inorganic crystal nucleating agent was not compatible with PVDF (including PMMA) and was not sufficiently dispersed. In addition, an organic crystal nucleating agent was also examined, but a sufficient effect was not obtained, and the reason was considered that there was a problem in dispersibility with PVDF (including PMMA).

Therefore, it is relatively easy to obtain as a heat-resistant resin powder, and since PVDF (including PMMA) is the same fluorine-based resin, fine powdery PTFE considered to be excellent in dispersibility is used as a crystal nucleus. Attempted to use as an agent.

When fine powdered PTFE is used as a crystal nucleating agent for PVDF (including PMMA), according to the DSC curve at lower temperature (see FIG. 1), the crystallization temperature ( The peak) moved to the high temperature side even near 10 ° C., and it was confirmed that it had an effect as a crystal nucleating agent. Thus, the present inventors have found that fine powdered PTFE exhibits a high ability as a crystal nucleating agent when added in a small amount as a crystal nucleating agent.

Furthermore, the present inventors surprisingly conducted an accelerated test at 80 ° C. for 60 minutes corresponding to several months of standing at room temperature, which is a durability evaluation of the PVDF film when fine powdered PTFE is used as a crystal nucleating agent. As a result, it was found that the elongation at break in the TD direction did not decrease so much and no change in anisotropy occurred.
The present invention has been completed based on these findings.

According to the present invention, there is provided (1) a PVDF composition containing PVDF, a colorant, and finely powdered PTFE as a crystal nucleating agent.
Further, according to the present invention, (2) when the PVDF composition is 100% by mass, the colorant is contained in an amount of 1 to 50% by mass, and the addition amount of fine powdered PTFE is contained in a proportion of 0.01 to 5% by mass. The PVDF composition of (1) is provided.
Moreover, according to this invention, (3) The PVDF composition of said (1) or (2) whose colorant is a titanium oxide is provided.
In addition, according to the present invention, there is provided (4) the PVDF composition according to any one of (1) to (3), wherein the particle size of finely divided PTFE is 0.01 to 4 μm.

The present invention also provides (5) the PVDF composition according to any one of (1) to (4), further comprising a methacrylate resin.
According to the present invention, (6) when the mixing ratio of PVDF and methacrylate resin is 100 parts by mass of PVDF and methacrylate resin, PVDF is 60 parts by mass or more and less than 100 parts by mass. The PVDF composition according to the above (5), wherein the methacrylate resin is more than 0 parts by mass and 40 parts by mass or less.

According to the present invention, (7) any one of the above (1) to (6), wherein the PVDF is at least one selected from the group consisting of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer. A PVDF composition is provided.
The present invention also provides (8) the PVDF composition according to (5), wherein the methacrylate resin is PMMA.

The present invention also provides (9) the PVDF composition according to any one of (1) to (8), further comprising a heat stabilizer.
Furthermore, according to the present invention, there is provided (10) a resin molded body formed from the PVDF composition according to any one of (1) to (9).

Further, according to the present invention, (11) the ratio (acceleration) between the TD direction breaking elongation of the resin molded body after the acceleration test (80 ° C. for 60 minutes) and the TD direction breaking elongation of the resin molded body at the beginning of formation. The TD-direction breaking elongation of the resin molded body after the test (80 ° C. for 60 minutes) / the TD-direction breaking elongation of the resin molded body at the beginning of formation × 100) is in the range of 60 to 100% (10 ) Resin molded body is provided.

Moreover, according to this invention, (12) The resin molded body of the said (10) which heat-processed the said resin molded body.
In addition, according to the present invention, (13) a resin film obtained from the resin molded body of any one of (10) to (12) is provided.
Moreover, according to this invention, the protective sheet obtained from the resin film of (14) said (13) is provided.
Moreover, according to this invention, the solar cell module backsheet obtained from the protective sheet of (15) said (14) is provided.

The present invention provides a PVDF composition containing PVDF, a colorant, and fine powdery PTFE as a crystal nucleating agent. For example, when a film is formed, the breaking elongation of MD and TD due to change with time Thus, there is an effect that a resin film in which a difference (anisotropy) in mechanical characteristic values such as the above does not increase so much can be obtained. As described above, the resin molded body of the present invention can be used as a protective sheet for resin films, various members, and equipment because the problem of anisotropic change with time is solved. As an effect.

FIG. 1 is a DSC curve at a temperature drop when a crystal nucleating agent (BN, PTFE) is used and when a crystal nucleating agent is not used.

1. Vinylidene fluoride resin PVDF used in the present invention means a homopolymer of vinylidene fluoride and a vinylidene fluoride copolymer mainly composed of vinylidene fluoride. That is, in the present invention, the vinylidene fluoride resin is at least one selected from the group consisting of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer.

The vinylidene fluoride homopolymer is a polymer using only vinylidene fluoride as a polymerizable monomer.
The vinylidene fluoride copolymer is a copolymer using vinylidene fluoride and a monomer copolymerizable therewith as a polymerizable monomer.

Examples of monomers copolymerizable with vinylidene fluoride include perfluoroalkyl such as hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, vinyl fluoride, perfluoromethyl vinyl ether, and perfluoroethyl vinyl ether. Can be mentioned. Moreover, ethylene, propylene, etc. which do not have a fluorine can also be copolymerized.

Examples of the vinylidene fluoride copolymer include a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, a vinylidene fluoride-chlorotrifluoroethylene copolymer, and a vinylidene fluoride-tri A fluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene terpolymer, a vinylidene fluoride-chlorotrifluoroethylene-hexafluoropropylene terpolymer, and a mixture of two or more thereof. Can be mentioned.

The vinylidene fluoride copolymer has a copolymerization ratio with vinylidene fluoride, that is, the copolymerization ratio of the copolymerizable monomer is 100 mol of the total amount of the copolymerizable monomer with vinylidene fluoride. %, It is usually 15 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less. When the copolymerization ratio of the copolymerizable monomer is 15 mol% or less, the vinylidene fluoride copolymer becomes a thermoplastic resin having crystallinity. The lower limit of the copolymerization ratio of the copolymerizable monomer is preferably 1 mol%. If the copolymerization ratio of the copolymerizable monomer becomes too high, the vinylidene fluoride copolymer loses crystallinity and becomes an elastomer.

Therefore, at least one selected from the group consisting of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer having a copolymerization ratio of 15 mol% or less can be used as PVDF. Among PVDF, vinylidene fluoride homopolymer and vinylidene fluoride-hexafluoropropylene copolymer having a copolymerization ratio of hexafluoropropylene units of 15 mol% or less are excellent in heat resistance, melt moldability, and mechanical properties. From the viewpoints of antifouling property, solvent resistance, secondary workability, etc., it is preferable.

The intrinsic viscosity of PVDF is preferably in the range of 0.7 to 1.5 dl / g, more preferably 0.8 to 1.3 dl / g. The intrinsic viscosity of PVDF is a logarithmic viscosity at 30 ° C. measured using a Ubbelohde viscometer for a solution in which 4 g of PVDF is dissolved in 1 liter of N, N-dimethylformamide.
The melting point of PVDF is a value measured from an endothermic peak at the time of temperature rise of a differential scanning calorimeter (DSC), and is usually within a range of 130 to 185 ° C., preferably 160 to 185 ° C.

2. Methacrylate-based resin In the PVDF composition of the present invention, a methacrylate-based resin may be mixed in order to improve properties such as processability and adhesiveness of PVDF. The methacrylate resin is a methacrylic acid alkyl ester homopolymer, a copolymer containing methacrylic acid alkyl ester as a main component, or a mixture of two or more of these polymers.

The copolymer having a methacrylic acid alkyl ester as a main component is a copolymer of a methacrylic acid alkyl ester and a monomer copolymerizable therewith.
When the total amount of the methacrylic acid alkyl ester and the copolymerizable monomer is 100 mol%, the copolymerizable monomer is usually less than 50 mol%, preferably less than 40 mol%, more preferably It is less than 30 mol%.

Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, etc. Among them, methyl methacrylate is preferable.
For example, a homopolymer of methyl methacrylate (hereinafter sometimes abbreviated as “PMMA”) uses only methyl methacrylate as a polymerizable monomer.

Monomers that can be copolymerized with alkyl methacrylates include alkyl methacrylates other than the principal alkyl methacrylates; alkyl alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Styrene monomers such as styrene and α-methylstyrene; nitrile monomers such as acrylonitrile and methacrylonitrile; vinyl monomers such as vinyl acetate;

Among these methacrylate resins, PMMA is preferable because it improves compatibility with PVDF and, for example, when a resin film is formed, improves adhesiveness with other resin films.
If the amount of the methacrylate resin is too large, properties such as weather resistance of PVDF may be impaired. If the amount is too small, for example, the properties of the resin film may be impaired.

3. Colorant In the PVDF composition of the present invention, a colorant is added. The colorant is not particularly limited as long as it does not impair the color tone and hiding power (light scattering property) of the PVDF composition, but the color tone and hiding power (light scattering property) are particularly excellent. Inorganic pigments and black pigments can be preferably used. Examples of inorganic pigments include TiO ₂ (titanium oxide), Al ₂ O ₃ .nH ₂ O, [ZnS + BaSO ₄ ], CaSO ₄ .2H ₂ O, BaSO ₄ , PbCO ₃ .Pb (OH) _2, etc. TiO ₂ (titanium oxide) which is a white pigment is preferable. The black pigment is preferably carbon black, and is not particularly limited as long as it is carbon black that is usually used for solar battery backsheets, etc., and furnace black, channel black, acetylene black, thermal black, etc. can be used. Carbon black whose surface has been modified with a carboxyl group or the like can also be used.

4). Fine powdery PTFE crystal nucleating agent In the PVDF composition of the present invention, a fine powdery PTFE crystal nucleating agent is added. The fine powdery PTFE is finely powdered, and the component forming the nucleating agent is necessarily formed by including PTFE. For example, tetrafluoroethylene homopolymer, tetrafluoroethylene and copolymerizable therewith It is important that the copolymer is a copolymer with a fluorine-based monomer other than tetrafluoroethylene or a modified PTFE, and thereby the effect as the crystal nucleating agent of the present invention can be exhibited. In order for PTFE to be finely divided, the average particle size of the primary particles is usually 0.01 to 4 μm, preferably 0.01 to 3 μm, more preferably 0.01 to 2 μm, and still more preferably 0.01 to 1 μm. Even if the fine powdery PTFE crystal nucleating agent used in the present invention is used in combination with a colorant, or is used in combination with a colorant and, if desired, a methacrylate resin or a heat stabilizer, it is suitable for PVDF. It is characterized by excellent dispersibility and sufficient effect as a crystal nucleating agent.

That is, in the present invention, it is a PVDF composition having an average particle size of PTFE of usually 0.01 to 4 μm. The average particle size is measured by a laser refraction / scattering method.

5. PVDF Composition The PVDF composition of the present invention is a PVDF composition comprising PVDF, a colorant, and finely powdered PTFE as a crystal nucleating agent.
A PVDF composition containing 1 to 50% by weight of a colorant and 0.01 to 5% by weight of finely divided PTFE is preferable when the PVDF composition is 100% by weight.
The PVDF composition of the present invention preferably contains 40 to 99.99% by mass of PVDF, assuming 100% by mass of the PVDF composition.
Furthermore, the PVDF composition containing methacrylate resin may be sufficient.

When the total weight of PVDF and methacrylate resin is 100 parts by mass when the methacrylate resin is included, the PVDF and methacrylate resin mixing ratio of PVDF is 60 parts by mass or more and less than 100 parts by mass, preferably 65 parts by mass. 95 parts by mass or less, more preferably 70 parts by mass or more and 90 parts by mass or less, and the methacrylate resin exceeds 0 part by mass and 40 parts by mass or less, preferably 5 parts by mass or more and 35 parts by mass or less, more preferably 10 parts by mass. The amount is 30 parts by mass or less. If the amount of the methacrylate resin is small, the adhesive effect cannot be obtained, and if the amount of the methacrylate resin is too large, the weather resistance and electrical characteristics, which are the characteristics of PVDF, may be deteriorated.

The content of the colorant of the present invention is 1 to 50% by mass, preferably 2 to 45% by mass, more preferably 3 to 40% by mass, when the PVDF composition is 100% by mass. In particular, since it is used as a colored film for a back sheet for a solar cell module, when titanium oxide is used, the titanium oxide is 15 to 50% by mass, preferably 20 to 50% by mass, more preferably 22 to 50% by mass. Is within the range.

The content of the fine powdery PTFE crystal nucleating agent of the present invention is such that when the PVDF composition is 100% by mass, the amount of PTFE added is 0.01-5% by mass, preferably 0.01-4.5% by mass. More preferably, the content is 0.05 to 3% by mass, and particularly preferably 0.1 to 2% by mass.
That is, in the present invention, the PVDF composition has an addition amount of PTFE of 0.01 to 5% by mass when the PVDF composition is 100% by mass.

In particular, when a methacrylate resin is used, when the PVDF composition is 100% by mass, the amount of PTFE added is 0.01 to 3% by mass, preferably 0.05 to 2.7% by mass. More preferably, the content is 0.1 to 1.8% by mass.
That is, in the present invention, when a methacrylate resin is used, the PVDF composition has an addition amount of PTFE of 0.01 to 3 mass% when the PVDF composition is 100 mass%.

If the amount of fine powdered PTFE added is small, the effect as a crystal nucleating agent cannot be obtained, while if it is large, the effect as a crystal nucleating agent is saturated and meaningless, and if too much, the properties as PVDF may be impaired. .
When fine powdery PTFE is added to PVDF as a crystal nucleating agent, the crystallization temperature is measured from the exothermic peak when the temperature is lowered by a differential scanning calorimeter (DSC).

The crystallization temperature is usually 8 to 30 ° C. higher than the crystallization temperature of PVDF to which no crystal nucleating agent is added. Preferably, it is increased by 10 to 28 ° C, more preferably 12 to 25 ° C.
That is, the present invention is a PVDF composition using PVDF in which the crystallization temperature of PVDF added with a crystal nucleating agent is 8 to 30 ° C. higher than the crystallization temperature of PVDF when no crystal nucleating agent is added.

The particle size and addition amount of fine powdered PTFE are adjusted so as to achieve such a crystallization temperature.
Further, the temperature difference between the melting point of PVDF and the crystallization temperature is usually 45 to 15 ° C., preferably 43 to 20 ° C., more preferably 40 to 25 ° C.
That is, the present invention is a PVDF composition using PVDF in which the temperature difference between the crystallization temperature and the melting point of PVDF added with a crystal nucleating agent is 45 to 15 ° C.

5-1. Heat Stabilizer In the PVDF composition of the present invention, a heat stabilizer is added as necessary. The heat stabilizer is used to prevent a decrease in heat resistance due to the addition of a colorant such as titanium oxide. By using a colorant and a heat stabilizer in combination, a colored film free from molding processing, thermal decomposition and thermal discoloration over time can be obtained.

It is known that when a large amount of a colorant such as titanium oxide is used as a back sheet for a solar cell module, the heat resistance of PVDF is lowered. In that case, a heat stabilizer is added. Examples of the heat stabilizer include polyhydroxymonocarboxylic acid calcium salt, aliphatic carboxylic acid calcium salt having 5 to 30 carbon atoms, calcium carbonate, calcium hydroxide, zinc oxide, and magnesium oxide. In addition, talc known as a filler is also known to have an effect as a heat stabilizer.

The content of the heat stabilizer of the present invention is within the range of 0 to 10% by mass, preferably 0.2 to 6% by mass, more preferably 0.3 to 3% by mass, when the PVDF composition is 100% by mass. It is.

If the content ratio of the heat stabilizer is too small, the heat stabilization effect is reduced, and if the content ratio of the heat stabilizer is too large, the color tone and mechanical characteristics of the resin film may be adversely affected.

5-2. Other Thermoplastic Resins The PVDF composition of the present invention contains PVDF as a resin component and, if necessary, a methacrylate resin, in order to improve properties such as processability, impact resistance, adhesion, and heat resistance. If desired, other thermoplastic resins can be contained.

Other thermoplastic resins include polyolefins such as polyethylene and polypropylene; polyamides such as nylon 6 and nylon 66; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; acrylic resins other than methacrylate resins; polystyrene and polyacrylonitrile , Polyvinyl chloride, polyoxymethylene, polycarbonate, polyphenylene oxide, polyester urethane, poly m-phenylene isophthalamide, poly p-phenylene terephthalamide, and the like.
The other thermoplastic resin is 0 to 15% by mass, preferably 0 to 12% by mass, and more preferably 0 to 10% by mass when the PVDF composition is 100% by mass.
When there are too many other thermoplastic resins, there exists a possibility that characteristics, such as a weather resistance of PVDF, may be impaired.

If desired, the PVDF composition of the present invention may contain a pigment dispersant, an ultraviolet absorber, a light stabilizer, a matting agent, a lubricant, a color adjuster, a processing aid, a mechanical property improver (for example, an elastomer such as an acrylic elastomer). ) And other additives selected from the above. These additives are used in proportions suitable for each as desired.
The amount of the additive is independently 15% by mass or less, preferably 10% by mass or less, when the PVDF composition is 100% by mass.

When these additives are used, the lower limit of the content ratio is usually 0.001% by mass and in many cases 0.01% by mass, when the PVDF composition is 100% by mass.

6). Resin molded body, resin film, protective sheet, back sheet for solar cell module The PVDF composition of the present invention is usually PVDF, a colorant, and fine powdered PTFE, and if necessary, a methacrylate resin and / or a thermal stabilizer. Can be prepared by a dry blending method. PVDF powder or pellets are fed into an extruder together with fine powdered PTFE, colorant, and optionally a methacrylate resin and / or heat stabilizer, melt kneaded, melt extruded into strands, cut and pelleted It can also be blended by conversion. When other additives and / or other thermoplastic resins are used, they can be contained in the blending step or the pellet step.

Such a blend can be fed to an extruder and melt extruded as a film (including sheets).
In this manner, the PVDF composition of the present invention can form a resin molded body.

6-1. Resin film As a resin molded body, the PVDF composition of the present invention can be formed into a film by supplying it to an extruder and melt-extruding it into a film form from a T-die placed at the tip of the extruder. it can. In the present invention, the resin film includes not only a film having a thickness of less than 250 μm but also a sheet (including a plate) having a thickness of 250 μm to 3 mm, preferably 250 μm or more and less than 2.5 mm. That is, the resin molded body is a resin molded body that is a resin film.

The lower limit of the thickness of the resin film is usually 2 μm, preferably 3 μm, more preferably 4 μm, and particularly preferably 5 μm. The upper limit value of the thickness of the resin film is preferably 500 μm, more preferably 300 μm, still more preferably 200 μm, and particularly preferably 120 μm. If the thickness of the resin film is too thin, the mechanical properties are deteriorated. If the thickness of the resin film is too thick, flexibility may be impaired or weight reduction may be difficult. The thickness of the resin film can exhibit good characteristics particularly in the range of 5 to 100 μm.

6-2. Protective sheet The resin film obtained from the PVDF composition of the present invention has abrasion resistance and weather resistance, and further has adhesiveness and, for example, when a resin molded body such as a film is formed, by heat treatment, the elongation at break etc. The anisotropy of the mechanical strength is improved, and it can be used as a protective sheet for various members / equipment ranging from daily goods to electrical / electronic parts. That is, the resin film is a resin molded body that is a protective sheet.

In that case, a single layer or a multilayer can be used. In the case of multi-layers, various lamination methods such as wet lamination using an adhesive, dry lamination, co-extrusion lamination, injection molding lamination injection press, and in-mold molding are possible.

6-3. Back sheet for solar cell module In the present invention, when a back sheet for a solar cell module is used as a protective sheet, a single-layer resin film comprising the PVDF composition of the present invention, the resin film and other resin films (for example, PET film), a multilayer film composed of the resin film and a moisture-proof film, a composite material composed of the resin film and a tempered glass plate, and a composite of the resin film and a metal plate The composite material is used as a composite material in which the resin film is combined with two or more of other resin films, a moisture-proof film, a tempered glass plate, and the like. That is, the protective sheet is a resin molded body that is a solar cell module backsheet. Multilayer films and composite materials can have an adhesive layer between each layer. Examples of the moisture-proof film include a composite film in which a deposited film of an inorganic oxide such as silicon oxide or aluminum oxide is formed on one surface of a base film. Moreover, the resin film and EVA sheet | seat which consist of the PVDF composition of this invention can be compounded, and it can also be set as the sealing material of a photovoltaic cell.

6-4. Accelerated test This is a test method for evaluating anisotropy change with time, and may be abbreviated as the initial stage of production of a resin molded body or resin film obtained from the composition of the present invention (hereinafter referred to as “initial stage of formation”). ) Is a test for evaluating whether the elongation at break can be maintained at room temperature for several months (approximately three months).
In this acceleration test, after performing an acceleration test at 80 ° C. for 60 minutes, the elongation at break in the TD direction and the MD direction were measured.

In this case, the ratio of the TD-direction breaking elongation of the resin molded article after the acceleration test at 80 ° C. for 60 minutes corresponding to standing at room temperature for several months and the TD-direction breaking elongation of the resin molded article at the beginning of formation ((80 ° C. for 60 minutes) TD-direction elongation at break of resin molded body after acceleration test) / (TD-direction elongation at break of formed resin body) × 100) (ratio:%) is usually within the range of 60 to 100%, preferably Is 70 to 100%, more preferably 80 to 100%.

That is, in the present invention, the ratio of the TD direction breaking elongation of the resin molded article after the accelerated test (80 ° C. for 60 minutes) to the TD direction breaking elongation of the resin molded article at the beginning of formation ((accelerated test (80 ° C. for 60 minutes) TD direction breaking elongation of the later resin molded body) / (TD direction breaking elongation of the initial resin molded body) × 100) (ratio:%) is in the range of 60 to 100%. is there.

In the present invention, the ratio between the TD direction breaking elongation of the resin molded body after the acceleration test (80 ° C. for 60 minutes) and the MD direction breaking elongation of the resin molded body after the acceleration test (80 ° C. for 60 minutes) ((acceleration TD direction elongation at break of resin molded body after test (80 ° C. for 60 minutes) / (MD direction elongation at break of resin molded body after accelerated test (80 ° C. for 60 minutes)) × 100) (ratio:%) In general, it is 50 to 90%, preferably 55 to 90%, more preferably 60 to 90%.

6-5. Pressure cooker test Further, a pressure cooker test (hereinafter sometimes abbreviated as "PCT test") was performed to measure long-term durability, assuming that the resin molded body was exposed to sunlight outdoors. Then, the breaking elongation of TD direction and MD direction was measured.
In this PCT test, a pressure cooker tester was used, a test was conducted at a temperature of 121 ° C., a relative humidity of 100% RH, 2 atm, and 96 hours, and the elongation at break was measured.

In the present invention, after the PCT test, the ratio of the TD rupture elongation of the resin molded product after the PCT test and the MD rupture elongation of the resin molded product after the PCT test ((TDT rupture elongation after the PCT test) / (PCT The MD direction breaking elongation after test) is usually 30 to 70%, preferably 35 to 70%, more preferably 40 to 70%.

7). Heat treatment The accelerated test (80 ° C. for 60 minutes) can be said to be heat treatment. Looking at Example 1 in Table 1 to be described later, the TD after 60 minutes at 80 ° C. was measured by an accelerated test (heat treatment) at 80 ° C. for 60 minutes, even though the TD fracture elongation at the beginning of formation was 68.0%. The elongation at break is the same as 68.0%.

On the other hand, in the case of Comparative Example 1 (without nucleating agent), the TD breaking elongation after 60 minutes at 80 ° C. was 30.0% even though the initial TD breaking elongation was 79.0%. And has fallen significantly. Further, in the case of Comparative Example 2 (nucleating agent BN), the TD breaking elongation after 80 minutes at 80 ° C. was greatly increased to 31.0% even though the initial TD breaking elongation was 69.0%. It is falling.
From these results, it is understood that when fine powdery PTFE is used as the crystal nucleating agent, a decrease in the TD fracture elongation is suppressed by the acceleration test (heat treatment).

This means that when fine powdered PTFE is used as the crystal nucleating agent, the change in anisotropy with time is less likely to occur, but further, for example, the change in anisotropy is less likely to occur by performing heat treatment after a certain period of time. The period is extended.
The temperature and time of the heat treatment are usually 40 to 120 ° C. and 30 to 200 minutes, preferably 50 to 110 ° C. and 40 to 150 minutes, more preferably 60 to 100 ° C. and 45 to 100 minutes.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The measuring method of the crystallization temperature of the resin film which consists of a PVDF composition of this invention, and breaking elongation is as follows.

(Crystallization temperature)
Using a differential scanning calorimeter DSC7 manufactured by PerkinElmer Co., Ltd., using as a sample 10 mg of the melt-extruded and cooled solidified product of the blend prepared in Example 1, Comparative Example 1 and Comparative Example 2 described later, in a nitrogen gas atmosphere, The temperature was raised from 30 ° C. to 250 ° C. at a rate of 10 ° C./min, then held at 250 ° C. for 1 minute, and then lowered from 250 ° C. to 30 ° C. at a rate of 10 ° C./min, DSC curve Asked. The exothermic peak temperature in the temperature lowering process in this DSC curve was defined as the crystallization temperature (Tc2) (° C.).

(Measurement of elongation at break)
Using a tensile tester (“RTM-100” manufactured by Toyo Baldwin Co., Ltd.), the measurement was performed under the conditions of an initial sample length of 100 mm and a crosshead speed of 300 mm / min in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%.

(Accelerated test)
After heat treatment at 80 ° C. for 60 minutes, the elongation at break was measured.
(PCT test)
Using a pressure cooker tester, a test at a temperature of 121 ° C., a relative humidity of 100% RH, 2 atm, and 96 hours was conducted to promote environmental measures, and then the elongation at break was measured.

[Example 1]
PVDF (Kureha W # 850) 47.71% by weight, PMMA (Asahi Kasei Chemicals Delpowder-560F) 9.97% by weight, acrylic processing aid (Mitsubishi Rayon Metabrene P-530A, Metabrene S-2006) 20% by mass, cetyl 2-ethylhexanoate (Exepearl manufactured by Kao) 1.10%, titanium oxide (DuPont Taipure R101) 30.0% by mass, calcium carbonate (Takehara Chemical Industries SL2500, Shiroishi Industrial Co., Ltd., Brilliant-1500 2.50% by mass, fine powdered PTFE (KTL-500F manufactured by Kitamura Co., Ltd .: average particle diameter of 0.3 μm by laser refraction / scattering method) 0.30% by mass, calcium stearate 0.50% by mass, acetylene black 0. Blended 02% by mass, cylinder temperature 190 ° C, twin screw extruder (Toshiba ) After making the compounds, a single-screw extruder (manufactured by Pla Giken), molten at a resin temperature of 230 ° C. extruded, and cooled with a cooling roll of 90 ° C., to produce a 20μm thick film.
Using this film, the elongation at break of the untreated film at the beginning of formation, the accelerated and firm film and the PCT and firm film was measured.
The breaking elongation of the film was measured in the MD direction and the TD direction, respectively. The measurement results are shown in Tables 1 and 2.

[Comparative Example 1]
In Example 1, the powdered PTFE was not added as Comparative Example 1, PVDF (Kureha W # 850) 48.01% by mass, PMMA (Asahi Kasei Chemicals Delpowder-560F) 9.97% by mass, acrylic System processing aids (Metbrene P-530A, Metabrene S-2006, manufactured by Mitsubishi Rayon) 8.20% by mass, cetyl 2-ethylhexanoate (Exepal, manufactured by Kao) 1.10%, titanium oxide (Typure R101, manufactured by DuPont) 30. Example 1 from what blended 00 mass%, calcium carbonate (SL2500 made by Takehara Chemical Industry, Brilliant-1500 made by Shiroishi Kogyo Co., Ltd.) 2.50 mass%, calcium stearate 0.50 mass%, and acetylene black 0.02 mass% The breaking elongation of the film produced under the same conditions as in Example 1 was measured under the same conditions as in Example 1. It was. The measurement results are shown in Tables 1 and 2.
[Comparative Example 2]
In Example 1, instead of the fine powdered PTFE, PTFE was replaced with boron nitride (SCPI manufactured by ESK) as a crystal nucleating agent in Comparative Example 2, and PVDF (Kureha W # 850) 47.71. % By mass, PMMA (Del powder 560F manufactured by Asahi Kasei Chemicals), 9.97% by mass, acrylic processing aids (Metbrene P-530A, Metabrene S-2006 manufactured by Mitsubishi Rayon), 8.20% by mass, cetyl 2-ethylhexanoate ( Exopearl made by Kao) 1.10%, titanium oxide (DuPont Taipure R101) 30.00% by mass, calcium carbonate (SL2500 made by Takehara Chemical Industry, Brilliant-1500 made by Shiroishi Industrial Co., Ltd.) 2.50% by mass, boron nitride (Germany) ESK Company SCP1) 0.30% by mass, calcium stearate 0.50% by mass, AS From a blend of polyphenylene black 0.02% by mass, the elongation at break of the film prepared under the same conditions as in Example 1 was measured under the same conditions as in Example 1.
The measurement results are shown in Tables 1 and 2.

[Discussion]
Tables 1 and 2 show the following.
When there was no crystal nucleating agent (Comparative Example 1: 30% by mass of TiO ₂ ), the ratio of TD fracture elongation after acceleration test (80 ° C. for 60 minutes) / TD fracture elongation at the beginning of formation was 38.0%. there were.

The ratio of TD break elongation after the accelerated test (80 ° C. for 60 minutes) of Comparative Example 1 / MD break elongation after the accelerated test (80 ° C. for 60 minutes) was 24.8%.
As described above, the anisotropy of the resin molded body was increased by the acceleration test (it can be said that the anisotropy increased as the numerical value of the above ratio decreased).

When the crystal nucleating agent is finely powdered PTFE (Example 1), the ratio of TD rupture elongation after acceleration test (80 ° C. for 60 minutes) / TD rupture elongation at the beginning of formation is 100%.
The ratio of the TD break elongation after the accelerated test (80 ° C. for 60 minutes) of Example 1 / MD break elongation after the accelerated test (80 ° C. for 60 minutes) is 68%. As described above, the anisotropy of the molded resin did not increase so much by the accelerated test (it can be said that the anisotropy decreases as the numerical value of the ratio increases).
When the crystal nucleating agent is boron nitride (Comparative Example 2), the ratio of TD fracture elongation after accelerated test (80 ° C. for 60 minutes) / TD fracture elongation at the beginning of formation is 44.9%.

The ratio of the TD break elongation after the accelerated test (80 ° C. for 60 minutes) of Comparative Example 2 / MD break elongation after the accelerated test (80 ° C. for 60 minutes) is 30.1%.
Thus, the anisotropy of the resin molding increased by the accelerated test.

Furthermore, after a severe PCT test, when fine powdery PTFE was used as the crystal nucleating agent (Example 1), the elongation at break in the MD direction and the TD direction was no crystal nucleating agent (Comparative Example 1), A better numerical value was shown than in the case of the nucleating agent boron nitride (Comparative Example 2).

That is, the ratio of TD break elongation / MD break elongation after the PCT test was 49.4% in Example 1. On the other hand, in Comparative Example 1, it was 15.3%, and in Comparative Example 2, it was 28.6%. Clearly, Example 1 is better in terms of anisotropy than Comparative Examples 1 and 2.

Thus, when the fine powdery PTFE of the present invention is added as a crystal nucleating agent, the TD fracture elongation does not decrease and the anisotropy increases so much even after the accelerated test (80 ° C./60 minutes). do not do. Even after the PCT test at a temperature of 121 ° C., a relative humidity of 100% RH, 2 atm, and 96 hours, the breaking elongation in the MD direction and the TD direction is better than that without the crystal nucleating agent and the crystal nucleating agent boron nitride. showed that.

The PVDF composition of the present invention improves the weather resistance, chemical resistance, abrasion resistance, electrical properties, and processability of PVDF by adding fine powdery PTFE as a coloring agent and crystal nucleating agent to PVDF. In addition to being excellent, when a resin molded body is formed, a resin molded body in which anisotropy of mechanical strength such as elongation at break is not so increased even after an acceleration test corresponding to standing at room temperature for several months (that is, after aging). It can be obtained and its utility value can be greatly expanded in industry.

Claims (15)

1. A vinylidene fluoride resin composition containing a fine powdery tetrafluoroethylene resin as a vinylidene fluoride resin, a colorant, and a crystal nucleating agent.
2. 2. The fluoride according to claim 1, which contains 1 to 50% by weight of a colorant and 0.01 to 5% by weight of a finely divided tetrafluoroethylene resin when the vinylidene fluoride resin composition is 100% by weight. Vinylidene resin composition.
3. The vinylidene fluoride resin composition according to claim 1 or 2, wherein the colorant is titanium oxide.
4. The vinylidene fluoride resin composition according to any one of claims 1 to 3, wherein the fine powdery tetrafluoroethylene resin has an average particle diameter of 0.01 to 4 µm.
5. The vinylidene fluoride resin composition according to any one of claims 1 to 4, further comprising a methacrylate resin.
6. The mixing ratio of the vinylidene fluoride resin and the methacrylate resin is such that when the total mass of the vinylidene fluoride resin and the methacrylate resin is 100 parts by mass, the vinylidene fluoride resin is 60 parts by mass or more and less than 100 parts by mass. The vinylidene fluoride resin composition according to claim 5, wherein the methacrylate resin is more than 0 parts by mass and 40 parts by mass or less.
7. The vinylidene fluoride resin composition according to any one of claims 1 to 6, wherein the vinylidene fluoride resin is at least one selected from the group consisting of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer. .
8. The vinylidene fluoride resin composition according to claim 5, wherein the methacrylate resin is polymethyl methacrylate.
9. The vinylidene fluoride resin composition according to any one of claims 1 to 8, further comprising a heat stabilizer.
10. A resin molded body formed from the vinylidene fluoride resin composition according to any one of claims 1 to 9.
11. Ratio between the TD direction breaking elongation of the resin molded body after the acceleration test (80 ° C. for 60 minutes) and the TD direction breaking elongation of the resin molded body at the beginning of formation (the resin after the accelerated test (80 ° C. for 60 minutes) The resin molded article according to claim 10, wherein the TD-direction breaking elongation of the molded article / TD-shaped elongation at break at the beginning of formation x 100) is in the range of 60 to 100%.
12. The resin molded body according to claim 10, wherein the resin molded body is heat-treated.
13. A resin film obtained from the resin molded body according to any one of claims 10 to 12.
14. A protective sheet obtained from the resin film according to claim 13.
15. A back sheet for a solar cell module obtained from the protective sheet according to claim 14.

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