JP2015030850A - Polyvinyl acetal film excellent in transparency and heat breaking phenomenon suppression - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyvinyl acetal film which has excellent transparency and in which a heat breaking phenomenon can be suppressed.SOLUTION: The polyvinyl acetal film is characterized in that when a laminated glass sheet is produced by using the polyvinyl acetal film and the abutted surface of the polyvinyl acetal film on a glass sheet is checked, a ratio of the complex elastic modulus (GPa), which is calculated by nanoindentation measurement using a scanning probe microscope (SPM), of the uppermost part of a convex part and that (GPa) of the lowermost part of a concave part is 0.90 or lower and another ratio of the hardness (GPa), which is calculated by nanoindentation measurement using the SPM, of the uppermost part of the convex part and that (GPa) of the lowermost part of the concave part is also 0.90 or lower.

Description

  The present invention relates to a polyvinyl acetal film. More specifically, the present invention relates to a polyvinyl acetal film that is excellent in transparency when it is made into laminated glass, has good adhesion to glass, and hardly causes a thermal cracking phenomenon.

  Polyvinyl acetal typified by polyvinyl butyral is excellent in adhesiveness and compatibility with various organic and inorganic substrates and solubility in organic solvents. Various adhesives, binders for ceramics, various inks, paints, etc. It is widely used as a safety glass interlayer.

  Among these, a film containing polyvinyl acetal and a plasticizer is widely used as an interlayer film for laminated glass because it is excellent in adhesiveness and transparency with glass, mechanical strength and flexibility.

  The interlayer film for laminated glass has an effect on transparency and glass adhesiveness when it is made into laminated glass depending on the surface state, but usually the air generated between the glass and the film is removed by embossing. The shape is given and it is produced by combining glass and a film by thermocompression bonding (for example, refer to Patent Document 1).

  In addition, these laminated glasses have poor adhesion between the glass and film due to wrinkles, cracks, voids, and unevenness remaining at the interface, and due to imbalance between the glass and film bonding surfaces, the glass is exposed to sunlight and the surrounding low temperature. When the temperature difference from the part is remarkably generated, a thermal cracking phenomenon may occur in which the thermal stress is generated and the glass is broken. Although the thermal cracking phenomenon has been discussed in many literatures, it is necessary to use tempered glass for laminated glass or to process glass such as meshed glass, so the use as laminated glass is limited (for example, , See Patent Document 2).

Japanese Patent Laid-Open No. 6-127983 JP 2004-076458 A

  This invention solves the said subject, and it aims at providing the polyvinyl acetal film which is excellent in transparency and can suppress a heat crack phenomenon.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a polyvinyl acetal film satisfying a specific requirement is excellent in transparency and is less susceptible to thermal cracking, leading to the present invention. It was. That is, when the laminated glass is used, the hardness of the uppermost portion of the convex portion calculated by nanoindentation measurement with a scanning probe microscope (hereinafter abbreviated as “SPM”) on the surface of the film in contact with the glass. Said subject is achieved by providing the polyvinyl acetal film whose ratio of (GPa) and the hardness (GPa) of the lowest part of a recessed part is 0.90 or less.

  The polyvinyl acetal film of the present invention has a difference in the composite elastic modulus between the convex portion and the concave portion on the surface, and the convex portion having a low composite elastic modulus is more easily deformed than the concave portion when bonded to glass, and the glass and the film during thermocompression bonding. While letting the air layer created between them escape, the glass adhesiveness is maintained by preferentially changing the shape of the projections. For this reason, laminated glass with few wrinkles, cracks, voids, and minute irregularities remaining at the interface can be easily produced, and furthermore, there is no adhesion unevenness at the interface between the glass and the film, so that laminated glass with less thermal stress is obtained. Can do.

It is an example of the impression image after probe press-fit at the time of nanoindentation measurement of the polyvinyl acetal film obtained in the Example by SPM. It is an example of the load-displacement curve at the time of carrying out nanoindentation measurement of the polyvinyl acetal film obtained in the Example by SPM. It is an example of the figure showing the film surface of the polyvinyl acetal film concerning embodiment of this invention.

  The polyvinyl acetal film of the present invention has a micro uneven shape on the film surface in contact with the glass when it is made into a laminated glass, and the hardness of the uppermost portion of the convex portion of the film surface calculated by SPM nanoindentation measurement and It is preferable that the ratio is the polyvinyl acetal film having a ratio of the hardness of the lowermost portion of the recess, that is, (the hardness of the uppermost portion of the convex portion) / (the hardness of the lowermost portion of the concave portion) of 0.90 or less.

  The composite elastic modulus and hardness of the concave and convex portions on the film surface are measured by SPM. In the SPM measurement of the polyvinyl acetal film of the present invention, the load and the displacement of the press-in depth are detected by press-fitting a fine probe to the surface of the sample by a nanoindentation method, and the obtained load− The composite elastic modulus and hardness can be theoretically calculated from the displacement curve (unloading curve).

  In the SPM nanoindentation method, an imaging image at the time of probe press-fitting and a load-displacement curve at the time of probe press-fitting are obtained. As obtained data, for example, data as shown in FIGS. 1 and 2 is obtained. From the imaging of the film surface by SPM, the uppermost part of the convex part and the lowermost part of the concave part are visually identified before the probe is press-fitted, and the composite elastic modulus and hardness are calculated based on the load-displacement curve at each point. An indentation image after the probe press-fitting of the film surface, in which the composite elastic modulus and hardness are actually measured, is obtained as an image using the SPM imaging function as shown in FIG. By observing the residual depth and contact depth at that time from the load and contact area of the probe by this measurement, load-displacement curves at the time of press-fitting and unloading are shown as shown in FIG. The load-displacement curve (press-fit) is a curve indicating the load for each displacement applied to the probe until the probe is pushed in. The load-displacement curve (unloading) is the load applied to the probe after the probe has been pushed in. It is a curve which shows the load for every displacement until it becomes zero. In addition, each value including the composite elastic modulus and hardness generally obtained by the SPM nanoindentation method is W.S. C. Oliver and G.M. M.M. Pharr: J.M. Mater. Res. 7, 1564 (1992).

を用いて、算出できる。スティフネスＳは、荷重−変位曲線における除荷曲線の傾きから算出される。なお、前記除荷曲線の傾きは、高変位時における除荷曲線の傾き、つまり、プローブを圧入後、除荷の開始直後における除荷曲線の傾きを指す。接触投影面積Ａｃは、接触深さ（所定の圧入深さと最大荷重における除荷曲線の勾配から求められる接触点の周辺表面での表面変位の差）とプローブの幾何学的形状固有の定数および補正項から所定の式により求められる。 About the composite elastic modulus Er in this measurement, the equation (1) is calculated from the stiffness S and the contact projected area Ac:

Can be used to calculate. The stiffness S is calculated from the slope of the unloading curve in the load-displacement curve. The slope of the unloading curve refers to the slope of the unloading curve at the time of high displacement, that is, the slope of the unloading curve immediately after the start of unloading after inserting the probe. The contact projected area Ac is the contact depth (difference in surface displacement at the peripheral surface of the contact point determined from the slope of the unloading curve at a predetermined press-fit depth and maximum load), a constant and correction specific to the probe geometry. It is calculated | required by a predetermined formula from a term.

を用いて、算出できる。最大荷重Ｗｍａｘは、プローブを所定の圧入深さまで圧入した際における荷重を指すものである。 Regarding the hardness H in this measurement, the formula (2):

Can be used to calculate. The maximum load Wmax indicates a load when the probe is press-fitted to a predetermined press-fitting depth.

  The measurement conditions of the SPM nanoindentation method can be appropriately set. For example, the indentation pressure is 50 μN and the upper limit of the indentation depth is 200 nm.

  The polyvinyl acetal film of the present invention always has a concave elastic modulus and a convexity as measured by the SPM nanoindentation method. Accordingly, (the composite elastic modulus at the top of the convex portion) / (the composite elastic modulus at the bottom of the concave portion) or (the hardness of the uppermost portion of the convex portion) / (the hardness of the lowest portion of the concave portion) is always 1.00 or less. Become. If (the composite elastic modulus of the uppermost part of the convex part) / (composite elastic modulus of the lowermost part of the concave part) or (the hardness of the uppermost part of the convex part) / (the hardness of the lowermost part of the concave part) decreases, the composite elasticity On the contrary, (the composite elastic modulus at the uppermost part of the convex part) / (the composite elastic modulus at the lowermost part of the concave part) or (the hardness of the uppermost part of the convex part) / ( If the hardness of the lowermost part of the concave portion is close to 1.00, it means that there is no unevenness in the composite elastic modulus or hardness.

  The polyvinyl acetal film of the present invention has a ratio of the composite elastic modulus at the top of the convex portion and the bottom of the concave portion measured by the SPM nanoindentation method, that is, (the composite elastic modulus at the top of the convex portion). ) / (Combined elastic modulus at the bottom of the recess) is preferably 0.90 or less, and more preferably 0.70 or less. Further, (composite elastic modulus at the uppermost portion of the convex portion) / (composite elastic modulus at the lowermost portion of the concave portion) is more preferably 0.40 or more. By using a film satisfying such a range as an interlayer film for laminated glass, it is possible to obtain a laminated glass which is excellent in transparency and hardly causes a thermal cracking phenomenon.

  Further, the ratio of the hardness at the uppermost part of the convex part on the film surface to the lowermost part of the concave part, ie, (the hardness of the uppermost part of the convex part) / (the hardness of the lowest part of the concave part) is 0.90 or less, .70 or less is preferable. Further, (the hardness of the uppermost portion of the convex portion) / (the hardness of the lowermost portion of the concave portion) is more preferably 0.50 or more. By using a polyvinyl acetal film satisfying such a range as an interlayer film for laminated glass, it is possible to obtain a laminated glass that is excellent in transparency and hardly causes a thermal cracking phenomenon.

  When the ratio of the composite elastic modulus at the top of the convex part on the film surface and the bottom of the concave part measured by the SPM nanoindentation method is larger than 0.90, the difference in the composite elastic modulus between the concave part and the convex part is small. For this reason, the air escape generated between the glass and the film is insufficient, or the embossed shape is transferred as it is, and the devised shape of the embossed shape and strict management of temperature and humidity are required. In addition, when the ratio of the hardness at the uppermost portion of the film surface convex portion and the lowermost portion of the concave portion measured by the SPM nanoindentation method is larger than 0.90, similarly, the difference in hardness between the concave portion and the convex portion is For this reason, there is insufficient air escape between the glass and the film, or a state in which the embossed shape is transferred as it is, and it is necessary to devise the embossed shape and strictly control the temperature and humidity.

  The surface roughness of the polyvinyl acetal film is determined by a 10-point average surface roughness Rz obtained from a laser microscope. The 10-point average surface roughness Rz was obtained by extracting only the reference length from the roughness curve in the direction of the average line, and measuring from the average line of the extracted portion in the direction of the vertical magnification. The sum of the average absolute value of the altitude and the average absolute value of the altitude of the bottom valley from the lowest valley bottom to the fifth, and this value is expressed in micrometers (μm). JIS B0601 ( 1994).

  The surface roughness of the polyvinyl acetal film of the present invention preferably has an Rz value of 30 μm or more, more preferably 50 to 70 μm, and even more preferably 60 to 69 μm. For this reason, when the Rz value is smaller than 30 μm, air escape between the glass and the film may be insufficient, and when the Rz value is larger than 70 μm, the embossed shape is transferred as it is. It is because it may become such a state.

  The transparency of the laminated glass of the present invention can be evaluated by measuring the haze value with a haze meter. The apparatus uses a single-beam photometry method according to JIS K 7105 as D65 light, and uses a value when a haze value of 0.6% is used as a calibration standard plate as a reference value. The haze value is obtained from the diffuse transmittance and the total light transmittance, and a value calculated by (diffuse transmittance) / (total light transmittance) × 100 is used. The haze is preferably 1.0% or less, and most preferably 0.3% or less.

  About the glass adhesiveness of the polyvinyl acetal film of this invention, after crimping | bonding a polyvinyl acetal film and glass, after passing for 48 hours, it measures by measuring 90 degree peel adhesive force (N / 20mm) by an autograph. it can. As measurement conditions for 90 ° peel adhesive strength, for example, the peel angle is 90 °, the tensile speed is 300 mm / min, the temperature is 23 ° C., and the relative humidity is 50% RH. The peel adhesive strength is preferably 12 (N / 20 mm) or more, and more preferably 17 (N / 20 mm) or more.

  The polyvinyl acetal film of the present invention is obtained, for example, by kneading polyvinyl butyral, triethylene glycol di-2-ethylhexanoate as a plasticizer, and magnesium acetate tetrahydrate with a twin screw extruder, and using an extrusion die. Can be obtained and pressure-welded with an embossing roll having irregularities on the surface.

  The form of the polyvinyl acetal film of the present invention may be a single layer film or a laminated film. The production method is not particularly limited, and can be produced by a conventionally known method such as coextrusion molding, multilayer injection molding, or dry lamination. Further, in the case of a laminated film, in-die lamination in which the components of each layer are brought into contact with each other in the die or outside-die lamination in which the components are brought into contact with each other outside the die may be used. Moreover, although extrusion temperature is suitably selected, 150-300 degreeC is preferable and 180-250 degreeC is more preferable.

  Although the thickness of the polyvinyl acetal film of this invention is not specifically limited, It is preferable that it is 0.1 mm-2 mm, and it is more preferable that it is 0.15-1 mm. In order to make the ratio of the composite elastic modulus of the concavo-convex part 0.90 or less, it is necessary to increase the peripheral speed ratio (close to 1) and reduce the bank size as the film becomes thinner. In the case of a laminated film, the outer layer is preferably 0.05 mm or more from the viewpoint of surface irregularities.

  The polyvinyl acetal film of the present invention needs to have fine irregularities on at least one outermost surface. The shape of the concavo-convex shape is not particularly limited, but in consideration of the handleability (foaming property) when bonded to glass, a concavo-convex structure is formed on the surface of the film by a conventionally known method such as melt fracture or embossing. Is preferred.

  The production method of the polyvinyl acetal film having a composite elastic modulus difference or hardness difference in the uneven portion of the film surface is not particularly limited, but a roll obtained by embossing a nip roll at the die exit is used, A method is preferred in which an appropriate amount of resin is retained and is produced by bank molding in which a film is gradually fed from between the rolls.

  In the bank molding, as the molding conditions of the film having unevenness on the surface, for example, the resin temperature is 150 to 300 ° C., the roll temperature is 20 to 60 ° C., and the nip roll at the die outlet is the first roll from the die side, By managing the peripheral speed difference between the first roll and the second roll in the range of 0.5 to 0.9 by the peripheral speed ratio (= first roll / second roll) when the two rolls are used, the bank size is It becomes 1-10 mm, and the film from which the composite elastic modulus and hardness in the convex part and concave part of a surface differ is obtained. The resin temperature is preferably 180 to 250 ° C, and more preferably 190 to 220 ° C. When the resin temperature is lower than 150 ° C., the extrusion discharge amount becomes insufficient and the productivity tends to be inferior. When the resin temperature is higher than 300 ° C., the material is likely to be deteriorated. The roll temperature is preferably 25 to 50 ° C, and more preferably 35 to 45 ° C. When the roll temperature is lower than 20 ° C., anisotropy is likely to occur due to the orientation of the film. When the roll temperature is higher than 60 ° C., the film sticks to the roll, so that winding tends to be difficult. The peripheral speed ratio between the first roll and the second roll is preferably 0.5 to 0.8, and more preferably 0.55 to 0.75. When the peripheral speed ratio of the first roll and the second roll is smaller than 0.5, the resin pool becomes too much and the film shape is not stable, causing wrinkles and unevenness, and when larger than 0.9, There is no resin pool and it cannot be said that bank molding.

  The bank size of the polyvinyl acetal film of the present invention is preferably 1 to 10 mm, more preferably 1 to 8 mm, and further preferably 1 to 2 mm. As shown in FIG. 3, the bank size indicates the size of a resin pool portion (bank) generated on the upstream side of the gap between the first roll and the second roll, and from the film surface to the peripheral edge of the bank portion. Refers to the maximum distance.

  As a method for producing a film having a composite elastic modulus difference or hardness difference in the uneven portion of the film surface, in addition to bank molding, when embossing with a roll in film molding, rolls having different hardness in the convex portion and the concave portion are used. The method to use is mentioned. In this case, by making the convex part of the roll a hard material and making the concave part a material softer than the convex part, the composite elastic modulus and hardness of the concave part of the film can be made higher than the composite elastic modulus and hardness of the convex part. it can.

  Next, the polyvinyl acetal used in the present invention will be described. The average amount of hydroxyl groups of the polyvinyl acetal used in the present invention is not particularly limited, but is preferably 20 to 40 mol%, more preferably 23 to 38 mol%, and further preferably 25 to 36 mol%. Preferably, the content is 26 to 29 mol%. When the average hydroxyl group content of polyvinyl acetal is less than 20 mol%, the mechanical strength and the adhesion to glass may be reduced, and when the average hydroxyl group amount exceeds 40 mol%, the compatibility with the plasticizer is remarkably high. It tends to decrease.

  The degree of acetalization of the polyvinyl acetal is not limited, but is preferably 50 to 78 mol%, more preferably 60 to 74 mol%, and still more preferably 65 to 73 mol%. When the degree of acetalization of the polyvinyl acetal is less than 50 mol%, the compatibility with the plasticizer may be significantly reduced, and when the degree of acetalization exceeds 74 mol%, the mechanical strength of the film tends to be reduced. is there.

  The vinyl ester residue amount of polyvinyl acetal is not particularly limited, but is preferably 0.01 to 15 mol%, more preferably 0.01 to 10 mol%, and 0.01 to 5 mol%. More preferably. When the amount of vinyl ester residues is less than 0.01 mol%, it is difficult to produce industrially inexpensively, and when the amount of vinyl ester residues exceeds 15 mol%, the film is used for a long time. The vinyl ester residue is hydrolyzed, and the film tends to be colored by the generated carboxylic acid.

  The polyvinyl acetal used in the present invention is produced using polyvinyl alcohol as a raw material. Polyvinyl alcohol can be obtained by polymerizing a vinyl ester compound and saponifying the resulting polymer. it can. As a method for polymerizing the vinyl ester compound, conventionally known methods such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. As a polymerization initiator used for the polymerization, an azo initiator, a peroxide initiator, a redox initiator, or the like can be appropriately selected. For the saponification reaction, conventionally known alcoholysis or hydrolysis using an alkali catalyst or an acid catalyst can be applied. Among them, a saponification reaction using methanol as a solvent and a caustic soda (NaOH) catalyst is simple and most preferable.

  Examples of vinyl ester compounds include conventionally known carboxylic acid vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., with vinyl acetate being particularly preferred.

  Further, when the vinyl ester compound is polymerized, it can be copolymerized with other monomers as long as it does not contradict the gist of the present invention. Examples of other monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, and n-butyl acrylate. Acrylates such as i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-methacrylate Methacrylic acid esters such as propyl, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethyl acetate Acrylamide derivatives such as amide, N, N-dimethylacrylamide, diacetone acrylamide, acrylamide propane sulfonic acid and salts thereof, acrylamide propyl dimethylamine and salts thereof, quaternary salts thereof, N-methylol acrylamide and derivatives thereof; -Methacrylamide derivatives such as methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamideamidopropylamine and salts thereof, quaternary salts thereof, N-methylolmethacrylamide and derivatives thereof; methyl vinyl ether , Ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl Vinyl ethers such as til vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl acetate and allyl chloride Allyl compounds such as maleic acid ester or maleic anhydride, vinylsilyl compounds such as vinyltrimethoxysilane, isopropenyl acetate, and the like. These monomers are usually used in a proportion of less than 10 mol% with respect to the vinyl ester compound.

  The viscosity average polymerization degree of polyvinyl alcohol used as a raw material for the polyvinyl acetal used in the present invention is not particularly limited, and is appropriately selected depending on the application. The viscosity average polymerization degree of polyvinyl alcohol is preferably 150 to 3000, more preferably 200 to 2500, and still more preferably 1000 to 2500. If the viscosity average polymerization degree of polyvinyl alcohol is less than 150, the strength may be insufficient when formed into a film, and if the viscosity average polymerization degree of polyvinyl alcohol is more than 3000, the handleability of the resulting resin may deteriorate. is there.

  The polyvinyl acetal used in the present invention can be obtained, for example, by the following method, but is not limited thereto. First, an aqueous solution of polyvinyl alcohol having a concentration of 3 to 30% by mass is adjusted to a temperature range of 80 to 100 ° C., and the temperature is gradually cooled over 10 to 60 minutes. When the temperature of the aqueous solution is lowered to −10 to 30 ° C., an aldehyde and an acid catalyst are added, and an acetalization reaction is performed for 30 to 300 minutes while keeping the temperature constant. Thereafter, the reaction solution is heated to a temperature of 30 to 80 ° C. over 30 to 200 minutes, and the temperature is maintained for 1 to 6 hours. Next, the reaction liquid is preferably cooled to room temperature and washed with water, and then neutralized by adding a neutralizing agent such as an alkali, if necessary, washed with water and dried to obtain the polyvinyl acetal used in the present invention. can get.

  It does not specifically limit as an acid catalyst used for acetalization reaction, Any organic acid and inorganic acid can be used, For example, an acetic acid, paratoluenesulfonic acid, nitric acid, a sulfuric acid, hydrochloric acid etc. are mentioned. Among these, hydrochloric acid, sulfuric acid, and nitric acid are preferably used from the viewpoint of performing a stable acetalization reaction.

  Although the aldehyde used for the acetalization reaction of this invention is not specifically limited, It is preferable to use the polyvinyl acetal acetalized with the C1-C8 aldehyde. Examples of the aldehyde having 1 to 8 carbon atoms include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, 2-ethylbutyraldehyde, n-octylaldehyde, 2-ethylhexylaldehyde, benzaldehyde and the like. These may be used alone or in combination of two or more. Among these, aldehydes having 4 to 6 carbon atoms, particularly n-butyraldehyde, are preferably used in terms of transparency and adhesiveness to glass. That is, as the polyvinyl acetal, polyvinyl butyral is particularly preferable.

  The polyvinyl acetal film of the present invention may contain an antioxidant, an ultraviolet absorber, a plasticizer, an adhesion improver, and other additives as long as it is not contrary to the gist of the present invention.

  When the antioxidant is added to the polyvinyl acetal film of the present invention, the kind thereof is not particularly limited, and examples thereof include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among these, phenols System antioxidants are preferred, and alkyl-substituted phenolic antioxidants are particularly preferred.

  Examples of the phenolic antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, and octadecyl-3- (3,5-dit- Butyl-4-hydroxyphenyl) propionate, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), 4,4′-butylidene-bis (4-methyl-6-tert-butylphenol), 4 , 4′-butylidene-bis (6-tert-butyl-m-cresol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), bis (3-cyclohexyl-2-hydroxy-5-methyl) Phenyl) methane, 3,9-bis (2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) -2, , 8,10-tetraoxaspiro [5.5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2, 4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate) methane, Alkyl-substituted phenolic compounds such as triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate); 6- (4-hydroxy-3,5-di-t-butylanilino)- 2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3,5-dimethylanilino) -2,4-bis-octylthio-1, , 5-triazine, 6- (4-hydroxy-3-methyl-5-t-butylanilino) -2,4-bis-octylthio-1,3,5-triazine, 2-octylthio-4,6-bis- ( And triazine group-containing phenolic compounds such as 3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine.

  Examples of phosphorus antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, and tris (2-t-butyl). -4-methylphenyl) phosphite, tris (cyclohexylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphosphite, 9,10-dihydro-9-oxa-10-phos Faphenanthrene-10-oxide, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9 , 10-Dihydro-9-oxa-10-phosphaf Monophosphite compounds such as nanthrene; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-ditridecylphosphite), 4,4′-isopropylidene-bis (phenyl-dialkyl (C12 ~ C15) phosphite), 4,4'-isopropylidene-bis (diphenylmonoalkyl (C12-C15) phosphite), 1,1,3-tris (2-methyl-4-ditridecyl phosphite-5- and diphosphite compounds such as t-butylphenyl) butane and tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylene phosphite. Of these, monophosphite compounds are preferred.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, lauryl stearyl 3,3′-thiodipropionate, pentaerythritol-tetrakis- (Β-lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane.

  These antioxidants can be used alone or in combination of two or more. The addition amount of the antioxidant is preferably 0.001 to 5% by mass and more preferably 0.01 to 1% by mass with respect to the mass of the film. If the antioxidant is less than 0.001% by mass relative to the mass of the film, a sufficient antioxidant effect may not be obtained, and even if the antioxidant is more than 5% by mass, a remarkable effect can be expected. Absent.

  When adding a ultraviolet absorber to the polyvinyl acetal film of this invention, the kind is not specifically limited. As the ultraviolet absorber used, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] -2H— Benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2 Benzotriazole ultraviolet absorbers such as' -hydroxy-5'-t-octylphenyl) benzotriazole; 2,2,6,6-tetramethyl-4- Piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-dit -Butyl-4-hydroxybenzyl) -2-n-butylmalonate, 4- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3- ( Hindered amine ultraviolet absorbers such as 3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) -2,2,6,6-tetramethylpiperidine; 2,4-di-t-butylphenyl-3 , 5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, and the like.

  The addition amount of these ultraviolet absorbers is preferably 0.001 to 5% by mass and more preferably 0.01 to 1% by mass with respect to the mass of the film. If the amount of the ultraviolet absorber is less than 0.001% by mass, a sufficient ultraviolet absorbing effect may not be obtained, and even if the amount of the ultraviolet absorber exceeds 5% by mass, a remarkable effect cannot be expected. These ultraviolet absorbers may be used alone or in combination of two or more.

  The plasticizer to be added to the polyvinyl acetal film of the present invention includes carboxylic acid ester plasticizers such as monovalent carboxylic acid esters and polyvalent carboxylic acid esters, phosphoric acid ester plasticizers, and organic phosphites. In addition to plasticizers and hydroxycarboxylic acid ester plasticizers, polymer plasticizers such as polyesters, polycarbonates, and polyethers can also be used.

  As monovalent carboxylic acid ester plasticizers, monovalent carboxylic acids such as butanoic acid, isobutanoic acid, hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octylic acid, 2-ethylhexanoic acid, lauric acid and the like , A compound obtained by a condensation reaction with a polyhydric alcohol such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol and glycerin. Specific examples of the compound include triethylene glycol di-2-ethylhexanoate, triethylene glycol diisobutanoate, triethylene glycol di-2-hexanoate, triethylene glycol di-2-ethylbutanoate, triethylene glycol dilaurate, Ethylene glycol di-2-ethylhexanoate, diethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-2-ethylhexanoate, tetraethylene glycol diheptanoate, PEG # 400 di-2-ethylhexanoate, tri Examples include ethylene glycol mono-2-ethylhexanoate and glycerin tri-2-ethylhexanoate. Here, PEG # 400 represents polyethylene glycol having an average molecular weight of 350 to 450.

  Polyvalent carboxylic acid ester plasticizers include adipic acid, succinic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and other methanol, ethanol, butanol, hexanol , 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, compounds obtained by a condensation reaction with a monohydric alcohol having 1 to 12 carbon atoms such as benzyl alcohol. . Examples of specific compounds include dihexyl adipate, di-2-ethylhexyl adipate, diheptyl adipate, dioctyl adipate, di-2-ethylhexyl adipate, di (butoxyethyl) adipate, di (butoxyethoxyethyl) adipate , Mono (2-ethylhexyl) adipate, dibutyl phthalate, dihexyl phthalate, di (2-ethylbutyl) phthalate, dioctyl phthalate, di (2-ethylhexyl) phthalate, benzylbutyl phthalate, didodecyl phthalate, etc. For example, but not limited to.

  Phosphoric acid or phosphorous acid plasticizers include phosphoric acid or phosphorous acid and methanol, ethanol, butanol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol , Compounds obtained by a condensation reaction with an alcohol having 1 to 12 carbon atoms such as butoxyethoxyethanol and benzyl alcohol. Specific examples include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate, tri (butoxyethyl) phosphate, tri (2-ethylhexyl) phosphite. ) And the like.

  Hydroxycarboxylic acid ester plasticizers include hydroxycarboxylic acid monohydric alcohol esters; methyl ricinoleate, ethyl ricinoleate, butyl ricinoleate, methyl 6-hydroxyhexanoate, ethyl 6-hydroxyhexanoate, 6-hydroxyhexanoic acid Polybutyl alcohol ester of butyl, hydroxycarboxylic acid; ethylene glycol di (6-hydroxyhexanoic acid) ester, diethylene glycol di (6-hydroxyhexanoic acid) ester, triethylene glycol di (6-hydroxyhexanoic acid) ester, 3-methyl 1,5-pentanediol di (6-hydroxyhexanoic acid) ester, 3-methyl-1,5-pentanediol di (2-hydroxybutyric acid) ester, 3-methyl-1,5-pentanediol di (3- Hi Roxybutyric acid) ester, 3-methyl-1,5-pentanediol di (4-hydroxybutyric acid) ester, triethylene glycol di (2-hydroxybutyric acid) ester, glycerin tri (ricinoleic acid) ester, L-tartaric acid di (1 -(2-ethylhexyl)), castor oil and the like.

  Polyester plasticizers include oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexane Polycarboxylic acid such as dicarboxylic acid, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5 -Pentanediol, 3-methyl 2,4-pen Diol, 1,2-heptanediol, 1,7-heptanediol, 1,2-octanediol, 1,8-octanediol, 1,2-nonanediol, 1,9-nonanediol, 2-methyl-1, 8-octanediol, 1,2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4 Carboxyl obtained by alternately copolymerizing polyhydric alcohols such as cyclohexanediol, 1,2-bis (hydroxymethyl) cyclohexane, 1,3-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxymethyl) cyclohexane Ring-opening polymerization of acid polyesters and lactone compounds such as ε-caprolactone Examples thereof include carboxylic acid polyesters obtained. The terminal structure of these polyesters is not particularly limited, and may be a hydroxyl group or a carboxyl group, or may be an ester bond obtained by reacting a terminal hydroxyl group or a terminal carboxyl group with a monovalent carboxylic acid or a monohydric alcohol.

  Polycarbonate plasticizers include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5- Pentanediol, 3-methyl-2,4-pentanediol, 1,2-heptanediol, 1,7-heptanediol, 1,2-octanediol, 1,8-octanediol, 1,2-nonanediol, 1 , 9-nonanediol, 2-methyl-1,8-octanediol, , 2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1, Transesterification of polyhydric alcohols such as 2-bis (hydroxymethyl) cyclohexane, 1,3-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxymethyl) cyclohexane and carbonates such as dimethyl carbonate and diethyl carbonate And a polycarbonate compound obtained by alternating copolymerization. Although the terminal structure of these polycarbonate compounds is not particularly limited, a carbonate group or a hydroxyl group is preferable.

  Polyether plasticizers include polyethylene glycol, poly (1,2-propylene glycol), poly (1,3-propylene glycol), poly (1,2-butylene glycol), poly (1,3-butylene glycol) , Poly (1,4-butylene glycol), poly (2,3-butylene glycol), etc., ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1, Examples thereof include a random copolymer or a block copolymer of two or more compounds selected from 3-butylene glycol, 1,4-butylene glycol, and 2,3-butylene glycol.

  When using a plasticizer in this invention, it may be used independently and may use 2 or more types together. Although the usage-amount of a plasticizer is not specifically limited, It is preferable that it is 1-100 mass parts with respect to 100 mass parts of polyvinyl acetal contained in a polyvinyl acetal film, It is more preferable that it is 5-70 mass parts, 20-20. More preferably, it is 60 parts by mass. If the amount of plasticizer used relative to 100 parts by mass of polyvinyl acetal in the polyvinyl acetal film is less than 1 part by mass, a sufficient plasticizing effect may not be obtained, and the amount of plasticizer used may be increased from 100 parts by mass. However, a marked plasticizing effect cannot be obtained.

  The polyvinyl acetal film of this invention is used suitably for the use of the intermediate film for laminated glasses. Below, the case where the film of this invention is used for the use of the intermediate film for laminated glasses is demonstrated. The glass used when the film of the present invention is used as an interlayer film for laminated glass is not particularly limited. In addition to inorganic glass such as float plate glass, polished plate glass, mold plate glass, mesh plate glass, heat ray absorbing plate glass, polymethacrylic acid Conventionally known organic glasses such as methyl and polycarbonate can be used, and these may be colorless, colored, transparent or non-transparent. These may be used alone or in combination of two or more. Moreover, the thickness of the glass is not particularly limited, but is preferably 100 mm or less, and more preferably 10 mm or less from the viewpoint of actual use used as laminated glass such as for buildings and automobiles.

  Furthermore, by using the polyvinyl acetal film of the present invention as a filler for a solar cell module, it is suitably used in fields where sound insulation is required, in particular, building-integrated solar cells such as BIPV.

  The laminated glass of the present invention can be produced by a conventionally known method. Examples thereof include a method using a vacuum laminator device, a method using a vacuum bag, a method using a vacuum ring, and a method using a nip roll. . In addition, a method of adding to the autoclave process after provisional pressure bonding can be additionally performed.

In the case of using a vacuum laminator device, for example, a known device used for manufacturing a solar cell is used, and the pressure is 100 to 200 ° C., particularly 130 to 160 ° C. under a reduced pressure of 1 × 10 ^{−6 to} 3 × 10 ⁻² MPa. Laminated at temperature. A method using a vacuum bag or a vacuum ring is described in, for example, European Patent No. 1235683, and is laminated at 130 to 145 ° C. under a pressure of about 2 × 10 ⁻² MPa, for example.

  In the case of using a nip roll, for example, there is a method in which after the first temporary press-bonding at a temperature not higher than the flow start temperature of the plasticized polyvinyl acetal, the temporary press-bond is further performed under a condition close to the flow start temperature. Specifically, for example, after heating to 30 to 70 ° C. with an infrared heater or the like, degassing with a roll, further heating to 50 to 120 ° C., and then bonding or temporarily adhering by pressing with a roll. .

  The autoclave process that is additionally performed after the temporary pressure bonding depends on the thickness and configuration of the module and the laminated glass, but is, for example, 0.5 to 2 at a temperature of 130 to 145 ° C. under a pressure of 0.1 to 0.15 MPa. Implemented for hours.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following examples, “%” means “% by mass” unless otherwise specified.

  About polyvinyl acetal films obtained in Examples and Comparative Examples, 10-point average surface roughness measured with a laser microscope, composite elastic modulus and hardness in SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass The property was evaluated by the following method. The evaluation results are shown in Table 1.

(Measurement of 10-point average surface roughness Rz)
According to JIS B0601 (1994) and JIS B0031 (1994), 10-point average surface roughness Rz obtained from a laser microscope (manufactured by Keyence Corporation, VK-X200) was determined for the obtained film. The 10-point average surface roughness Rz was obtained by extracting only the reference length from the roughness curve in the direction of the average line, and measuring from the average line of the extracted portion in the direction of the vertical magnification. The sum of the average value of the absolute values of the altitude and the average value of the absolute values of the altitudes of the bottom valley from the lowest valley floor to the fifth was obtained, and this value was expressed in micrometers (μm).

(Measurement of composite elastic modulus and hardness in SPM nanoindentation measurement)
About the obtained film, the composite elastic modulus and hardness were measured by nanoindentation method using SPM (manufactured by Hitachi High-Tech Co., Ltd., multifunction SPM device). The measurement conditions are as follows: the temperature is 25 ° C., the relative humidity is 25% RH, the indentation pressure is 50 μN (indentation for 3 seconds), and the upper limit of the indentation depth is 200 nm. Depth displacement was detected. Based on the indented image obtained after the probe is press-fitted, the uppermost part of the convex part and the lowermost part of the concave part are identified visually, and the hardness and composite elasticity are determined from the load-displacement curve (unloading curve) at each point The rate was theoretically calculated by the method described above, and the average value was obtained.

(Measure haze)
About the obtained laminated glass, based on JISK7105, the haze value was evaluated with the haze meter (the Suga Test Instruments company make, XZ-1). The haze meter is a single-beam photometry method with D65 light as the measurement light, and a standard value when a haze value of 0.6% is used as the calibration standard plate, (diffuse transmittance) / (total light transmittance) × The value calculated at 100 was calculated as the haze value. The evaluation of haze is shown in three stages of A to C. A range of 0.3% or less is A, a range of 0.4 to 1.0% is B, and a range of 1.1% or more is C.

(Evaluation of glass adhesion)
After the polyvinyl acetal film and the glass were pressure-bonded, after 48 hours had elapsed, the 90 ° peel adhesive strength (N / 20 mm) was measured by an autograph to evaluate the adhesion of the obtained film to the glass. The measurement conditions for 90 ° peel adhesive strength were a peel angle of 90 °, a tensile speed of 300 mm / min, a temperature of 23 ° C., and a relative humidity of 50% RH. The evaluation of glass adhesion was shown in three stages of A to C. A range of 17 to 20 N / 20 mm was A, a range of 12 to 16 N / 20 mm was B, and a range of 0 to 11 N / 20 mm was C.

Example 1
In a 100 L SUS container equipped with a reflux condenser, thermometer, and squid type stirring blade, 660 parts of ion exchange water 8100 parts by mass, polyvinyl alcohol (hereinafter referred to as PVA) (viscosity average polymerization degree 1700, saponification degree 99 mol%) The mass part was charged (PVA concentration 7.5%), and the contents were heated to 95 ° C. and completely dissolved. Next, after gradually cooling to 5 ° C. with stirring at 120 rpm, 435 parts by mass of n-butyraldehyde and 540 ml of 20% hydrochloric acid were added, and a butyralization reaction was performed for 150 minutes. Thereafter, the temperature was raised to 50 ° C. over 60 minutes, held for 120 minutes, and then cooled to room temperature. The precipitated resin was washed with ion-exchanged water, an excess amount of aqueous sodium hydroxide solution was added, washed again, and dried to obtain polyvinyl butyral (hereinafter referred to as PVB). The resulting PVB had a butyralization degree (average acetalization degree) of 69 mol%, a vinyl acetate group content of 1 mol%, and a vinyl alcohol group content of 30 mol%. The degree of butyralization of PVB and the content of the remaining vinyl acetate groups were measured according to JIS K6728.

  100 parts by weight of the PVB obtained above, 38 parts by weight of triethylene glycol di-2-ethylhexanoate as a plasticizer, 0.048 parts by weight of magnesium acetate tetrahydrate, biaxially at a resin temperature of 200 ° C. When kneading using an extruder and extruding with a die, both the first roll and the second roll are embossed rolls having an Rz of 70 μm, the roll temperature is 30 ° C., and the peripheral speed of the first roll and the second roll By adjusting the ratio to 0.75, the bank size at the time of film formation was adjusted to 2 mm to obtain a polyvinyl acetal film having a film thickness of 760 μm. About this film, the composite elastic modulus and hardness in Rz and SPM nanoindentation measurement were measured.

Moreover, the laminated glass was obtained using this film as an intermediate film for laminated glass. The laminated glass was laminated at 140 ° C. under a reduced pressure of 2 × 10 ⁻² MPa using a vacuum laminator apparatus, and autoclaved for 2 hours at a temperature of 140 ° C. under a pressure of 0.1 MPa after temporary pressure bonding. About the obtained laminated glass, haze and glass adhesiveness were evaluated. The evaluation results are shown in Table 1.

(Example 2)
Melting was performed in the same manner as in Example 1 except that the bank size was adjusted to 2 mm by setting the roll temperature to 35 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.70. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

Example 3
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 2 mm by setting the roll temperature to 25 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.80. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

Example 4
Melting was carried out in the same manner as in Example 1 except that the bank size was adjusted to 2 mm by setting the roll temperature to 40 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.65. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 5)
Melting was carried out in the same manner as in Example 1 except that the bank size was adjusted to 3 mm by setting the roll temperature to 30 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.70. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 6)
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 3 mm when the roll temperature was 25 ° C. and the peripheral speed ratio between the first roll and the second roll was 0.75. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 7)
Melting was carried out in the same manner as in Example 1 except that the bank size was adjusted to 3 mm by setting the roll temperature to 40 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.60. Extrusion was performed to obtain a film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 8)
Melting was carried out in the same manner as in Example 1 except that the bank size was adjusted to 1 mm by setting the roll temperature to 30 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.80. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

Example 9
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 1 mm by setting the roll temperature to 25 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.90. Extrusion was performed to obtain a film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 10)
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 1 mm by setting the roll temperature to 40 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.70. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 11)
Melting was performed in the same manner as in Example 1 except that the bank size was adjusted to 5 mm by setting the roll temperature to 30 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.65. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 12)
It was melted by the same method as in Example 1 except that the bank size was adjusted to 5 mm by setting the roll temperature to 25 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.70. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 13)
It was melted by the same method as in Example 1 except that the bank size was adjusted to 5 mm when the roll temperature was 40 ° C. and the peripheral speed ratio between the first roll and the second roll was 0.55. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 14)
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 10 mm by setting the roll temperature to 30 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.60. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 15)
It was melted in the same manner as in Example 1 except that the bank size was adjusted to 10 mm by setting the roll temperature to 25 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.65. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 16)
Melting was performed in the same manner as in Example 1 except that the bank size was adjusted to 10 mm by setting the roll temperature to 40 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.50. Extrusion was performed to obtain a polyvinyl acetal film having a thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 17)
PVB was synthesized by the same method as in Example 1 except that n-butyraldehyde was changed to 514 parts by mass to obtain a polyvinyl acetal film. The resulting PVB had a butyralization degree of 78 mol%, a vinyl acetate group content of 1 mol%, and a vinyl alcohol group content of 21 mol%. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Example 18)
PVB was synthesized by the same method as in Example 1 except that n-butyraldehyde was changed to 340 parts by mass to obtain a polyvinyl acetal film. The resulting PVB had a butyralization degree of 52 mol%, a vinyl acetate group content of 1 mol%, and a vinyl alcohol group content of 47 mol%. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 1)
Set the roll temperature to 30 ° C, and make the peripheral speed of the first roll and the second roll the same, so that the bank size is not provided, and the clearance between the first cooling roll and the second cooling roll at the die outlet is Except for 720 μm, melt extrusion was performed in the same manner as in Example 1 to obtain a polyvinyl acetal film. A laminated glass was obtained by the same method as in Example 1 using the obtained film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 2)
Set the roll temperature to 40 ° C. and set the peripheral speed of the first roll and the second roll to be the same, so that the bank size is not provided and the clearance between the first cooling roll and the second cooling roll at the die outlet is set. Except that the thickness was 750 μm, melt extrusion was performed in the same manner as in Example 1 to obtain a film. A laminated glass was obtained by the same method as in Example 1 using the obtained film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 3)
Set the roll temperature to 40 ° C. and set the peripheral speed of the first roll and the second roll to be the same, so that the bank size is not provided and the clearance between the first cooling roll and the second cooling roll at the die outlet is set. Except for 720 μm, melt extrusion was performed in the same manner as in Example 1 to obtain a polyvinyl acetal film. A laminated glass was obtained by the same method as in Example 1 using the obtained film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 4)
Set the roll temperature to 25 ° C, and make the peripheral speed of the first roll and the second roll the same, so that the bank size is not provided, and the clearance between the first cooling roll and the second cooling roll at the die outlet is Except for 720 μm, melt extrusion was performed in the same manner as in Example 1 to obtain a polyvinyl acetal film. A laminated glass was obtained by the same method as in Example 1 using the obtained film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 5)
The roll temperature is 25 ° C., the bank size is not provided when the first roll and the second roll have the same peripheral speed, and the clearance between the first cooling roll and the second cooling roll at the die outlet is 750 μm. Except for the above, melt extrusion was performed in the same manner as in Example 1 to obtain a film. A laminated glass was obtained by the same method as in Example 1 using the obtained film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

(Comparative Example 6)
Except for using PVB used in Example 18, adjusting the bank size to 2 mm when the film was formed by setting the roll temperature to 25 ° C. and the peripheral speed ratio of the first roll to the second roll to 0.80. Then, melt extrusion was performed in the same manner as in Example 1 to obtain a polyvinyl acetal film having a film thickness of 760 μm. Moreover, the laminated glass was obtained by the method similar to Example 1 using this film. Table 1 shows the evaluation results of Rz, composite elastic modulus and hardness in the SPM nanoindentation measurement, haze and glass adhesion when made into laminated glass.

  As can be seen from Table 1, the polyvinyl acetal film (interlayer film for laminated glass) of the example in which the ratio of (the composite elastic modulus at the top of the convex part) / (the composite elastic modulus at the bottom of the concave part) satisfies the requirements of the present invention ) Has a low haze when it is made into a laminated glass and is excellent in adhesion to glass. Therefore, it is excellent in transparency and excellent in suppressing thermal cracking. As can be seen from the examples, the haze of the film having a 10-point average surface roughness in the range of 60.0 to 69.9 Rz is 0.3% or less. The ratio of (combined elastic modulus at the top of the convex portion) / (combined elastic modulus at the bottom of the concave portion) is 0.40 to 0.69, and (composite elastic modulus at the top of the convex portion) / ( It can be seen that the film having a composite elastic modulus at the bottom of the concave portion having a ratio of 0.50 to 0.69 is particularly excellent in haze and glass adhesion.

  The polyvinyl acetal film of the present invention is excellent in transparency and can suppress thermal cracking. Therefore, in the present invention, the film having a difference in the composite elastic modulus and hardness of the uneven portion on the surface is an interlayer film for laminated glass that is required to have excellent adhesion to glass, excellent transparency, and suppression of thermal cracking. Preferably used.

1 Film surface 2 Top of convex part 3 Bottom of concave part

Claims (9)

It is a film containing polyvinyl acetal and a plasticizer, and at least one of the film surfaces has a concavo-convex shape, and the hardness at the top of the convexity (GPa) calculated by SPM nanoindentation measurement and the hardness at the bottom of the concave ( GPa) is a polyvinyl acetal film having a ratio of 0.90 or less. The polyvinyl acetal film of Claim 1 whose 10-point average surface roughness Rz of the said film surface is 50-70 micrometers. The polyvinyl acetal film according to claim 1 or 2, wherein the ratio of the hardness (GPa) of the uppermost portion of the convex portion to the hardness (GPa) of the lowermost portion of the concave portion is 0.70 or less. The polyvinyl acetal film in any one of Claims 1-3 whose ratio of the hardness (GPa) of the uppermost part of a convex part and the hardness (GPa) of the lowest part of a recessed part is 0.50 or more. The polyvinyl acetal film in any one of Claims 1-4 whose 10-point average surface roughness Rz of a film surface is 60-69 micrometers. The intermediate film for laminated glasses which consists of a polyvinyl acetal film in any one of Claims 1-5. The solar cell sealing material which consists of a polyvinyl acetal film in any one of Claims 1-5. Laminated glass comprising the interlayer film for laminated glass according to claim 6. The solar cell module containing the solar cell sealing material of Claim 7.

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