Resin sheet and method for producing same

Abstract

The present invention addresses the problem of providing a resin sheet which has excellent heat resistance, which has a surface shape that conforms to the surface shape of glass when sandwiched between glass sheets as an interlayer film for laminated glass, and which is less likely to cause a gauge band in a wound roll body. The problem is resolved by a resin sheet containing a polyvinyl acetal resin, wherein the storage modulus E'(140) at 140°C is 0.4-7.0 MPa and unevenness in thickness is not more than 20.0%.

Description

Resin sheet and method for producing the same

[0001] The present invention relates to a resin sheet, and more particularly to a resin sheet used as an interlayer film for laminated glass.

[0002] Laminated glass is a composite glass in which a resin sheet made of a thermoplastic resin such as polyurethane, ethylene-vinyl acetate copolymer, or polyvinyl acetal resin is interposed between a plurality of plate-shaped glasses.

[0003] Since laminated glass is safe because glass fragments are less likely to scatter even when it is damaged by an external impact, it is widely used as front glass, side glass, rear glass of vehicles such as automobiles, and window glass of aircraft, buildings, etc.

[0004] In recent years, the required performance for laminated glass has become higher, and the laminated glass interlayer film that constitutes the laminated glass is also required to maintain excellent transparency regardless of the production conditions of the laminated glass, and to have excellent heat resistance and penetration resistance.

[0005] Patent Document 1 describes an acetalized product of an ethylene vinyl alcohol copolymer in which a symmetry coefficient representing an acetalization degree distribution and a melting peak temperature / midpoint glass transition temperature ratio representing a degree of crystallinity are adjusted to specific ranges, respectively. The resin sheet of Patent Document 1 has improved self-supporting properties and creep resistance in a high-temperature environment while maintaining high transparency and penetration resistance.

[0006] Patent Document 2 describes a modified vinyl acetal resin for an interlayer film of laminated glass in which the molar ratios of ethylene units and vinyl alcohol units constituting the resin and the acetalization degree are adjusted to specific ranges, respectively. The resin of Patent Document 2 is excellent in impact resistance and heat resistance, and is suitably used as a structural laminated glass interlayer film that requires penetration resistance and self-supporting properties in a high-temperature environment.

[0007] Patent Document 3 is an unpublished prior application. Patent Document 3 describes a laminated glass interlayer containing an α-olefin-modified polyvinyl acetal resin and a plasticizer of a specific structure. The laminated glass interlayer of Patent Document 3 can form laminated glass with excellent puncture resistance, edge peel resistance, and heat and moisture resistance.

[0008] International Publication No. 2022 / 220085, International Publication No. 2020 / 196186, Japanese Patent Application No. 2023-219053

[0009] Resins with excellent heat resistance have a high storage modulus and therefore are resistant to plastic deformation. However, resin sheets for heat-resistant laminated glass interlayers, which have a relatively high storage modulus, have problems such as the surface protrusions not being easily flattened even when compressed with glass, leading to residual optical distortion within the laminated glass interlayer and a decrease in transparency.

[0010] Furthermore, resin sheets are typically manufactured, stored, and distributed in roll form for reasons of productivity and handling. With each winding, variations in thickness of the resin sheet roll are amplified, deformation increases, and circumferentially extending band-shaped protrusions (also called gauge bands) are generated. When gauge bands are formed on a roll of resin sheet for laminated glass interlayers, the unwound resin sheet is significantly deformed, and when compressed with glass, the optical distortion remaining inside the laminated glass interlayer increases even further.

[0011] The present invention solves the aforementioned problems, and its objective is to provide a resin sheet that has excellent heat resistance, whose surface shape conforms to the surface shape of the glass when sandwiched between glass as an interlayer in laminated glass, and which is less prone to generating gauge bands when wound into a roll.

[0012] The present invention provides the following embodiments: [1] A resin sheet comprising a polyvinyl acetal resin, wherein the storage modulus E'(140) at 140°C is 0.4 to 7.0 MPa, preferably 1.0 to 4.0 MPa, more preferably 1.5 to 3.0 MPa, and in one embodiment 0.5 to 2.5 MPa, and the thickness uniformity is 20.0% or less, for example 12.5% ​​or less, preferably 12.0% or less, more preferably 8.0% or less, even more preferably 6.6% or less, even more preferably 5.0% or less, especially preferably 4.0% or less, and particularly preferably 3.0% or less.

[0013] [2] A resin sheet according to Embodiment 1, wherein the storage modulus E'(50) at 50°C is 20.0 to 600.0 MPa, preferably 30.0 to 200.0 MPa, more preferably 60.0 to 100.0 MPa, and in one embodiment 20.0 to 84.0 MPa.

[0014] [3] A resin sheet according to embodiment 1 or 2, wherein the storage modulus E'(70) at 70°C is 9.0 to 50.0 MPa, preferably 12.0 to 30.0 MPa, more preferably 14.0 to 20.0 MPa, and in one embodiment 9.0 to 19.5 MPa.

[0015] [4] A resin sheet according to any of embodiments 1 to 3, wherein the storage modulus E'(100) at 100°C is 2.0 to 20.0 MPa, preferably 4.0 to 15.0 MPa, more preferably 6.0 to 12.0 MPa, and in one embodiment 2.0 to 10.0 MPa.

[0016] [5] A resin sheet according to any of embodiments 1 to 4, wherein the haze of the resin sheet having a thickness of 900 μm, measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000, is 1.5% or less, preferably 0.7% or less, more preferably 0.55% or less, even more preferably 0.5% or less, even more preferably 0.45% or less, and particularly preferably 0.39% or less.

[0017] [6] A resin sheet according to any of embodiments 1 to 5, wherein the resin sheet having a thickness of 900 μm is immersed in water at 25°C for 300 hours, left for 24 hours under atmospheric conditions of 23°C and 50% RH, and then measured at a measurement temperature of 20°C under conditions compliant with JIS K7136:2000, the haze is 5.0% or less, preferably 4.5% or less, more preferably 3.5% or less, and even more preferably 2.5% or less.

[0018] [7] A resin sheet according to any of embodiments 1 to 6, including recovered raw materials.

[0019] [8] A resin sheet according to any one of embodiments 1 to 7, comprising a compound having a structure in which a hydrocarbon group having 6 or more carbon atoms, preferably 6 to 30, more preferably 8 to 22, even more preferably 10 to 20, and even more preferably 12 to 14, is bonded to a polyoxyalkylene group.

[0020] [9] The resin sheet of embodiment 8, wherein the compound is contained in 5 to 40 parts by mass, preferably 8 to 25 parts by mass, more preferably 10 to 22 parts by mass, even more preferably 12 to 19 parts by mass, and even more preferably 14 to 17 parts by mass, and in one embodiment 15 to 20 parts by mass, per 100 parts by mass of polyvinyl acetal resin.

[0021]

[10] A resin sheet according to any one of embodiments 1 to 9, wherein the polyvinyl acetal resin is an α-olefin modified polyvinyl acetal resin.

[0022]

[11] A resin sheet according to any one of embodiments 1 to 10, which is a melt-mixed extruded resin sheet.

[0023]

[12] A method for producing a resin sheet, comprising: melt-kneading a resin containing polyvinyl acetal resin having a storage modulus E'(140) at 140°C of 0.4 to 7.0 MPa, preferably 1.0 to 4.0 MPa, more preferably 1.5 to 3.0 MPa, and in one embodiment 0.5 to 2.5 MPa; melt-extruding the melt-kneaded material into a sheet; and solidifying the sheet-like melt-kneaded material on a casting drum.

[0024]

[13] A method for producing a resin sheet according to embodiment 12, wherein the melt-mixing temperature is 120 to 230°C, preferably 130 to 200°C, and more preferably 140 to 180°C.

[0025]

[14] A method for producing a resin sheet according to embodiment 12 or 13, wherein the specific energy of the melt kneading is 0.05 kWh / kg or more, preferably 0.10 kWh / kg or more, more preferably 0.15 kWh / kg or more, and even more preferably 0.20 kWh / kg or more.

[0026]

[15] A method for manufacturing a resin sheet according to any of embodiments 12 to 14, wherein the temperature of the casting drum is 10 to 120°C, preferably 20 to 90°C, and more preferably 25 to 60°C.

[0027]

[16] A method for producing a resin sheet according to any of embodiments 12 to 15, wherein the resin that is melt-kneaded includes recovered raw materials.

[0028]

[17] A method for producing a resin sheet according to any one of embodiments 12 to 16, wherein the resin to be melt-kneaded contains a compound having a structure in which a hydrocarbon group having 6 or more carbon atoms is bonded to a polyoxyalkylene group.

[0029]

[18] A laminated glass interlayer comprising a resin sheet according to any of embodiments 1 to 10.

[0030]

[19] Laminated glass interlayer including the resin sheet of embodiment 11.

[0031]

[20] Laminated glass having a plurality of glass plates and a laminated glass interlayer according to embodiment 18 disposed between the plurality of glass plates.

[0032]

[21] Laminated glass having a plurality of glass plates and a laminated glass interlayer according to embodiment 19 disposed between the plurality of glass plates.

[0033]

[22] Laminated glass having a plurality of glass plates and a laminated glass interlayer comprising a resin sheet of embodiment 5, or a resin sheet of embodiment 5 which is a melt-kneaded extruded resin sheet, disposed between the plurality of glass plates, wherein the haze measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000 is 1.5% or less, preferably 0.7% or less, more preferably 0.5% or less, and even more preferably 0.39% or less.

[0034]

[23] Laminated glass comprising a plurality of glass plates and a laminated glass interlayer comprising a resin sheet of embodiment 6, or a resin sheet of embodiment 6 which is a melt-kneaded extruded resin sheet, disposed between the plurality of glass plates, wherein the haze measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000 is 5.0% or less, preferably 4.5% or less, more preferably 3.5% or less, and even more preferably 2.5% or less.

[0035] The present invention provides a resin sheet that exhibits excellent heat resistance, whose surface shape conforms to the surface shape of the glass when sandwiched between layers of glass as an interlayer, and which is less prone to the formation of gauge bands when wound into a roll. As a result, the present invention can provide a resin sheet roll with excellent axial flatness and laminated glass without optical distortion. Furthermore, the present invention provides a resin sheet with excellent moisture resistance and transparency.

[0036] This is a schematic diagram showing a method for measuring the heat resistance of a sheet.

[0037] One embodiment of the present invention will be described in detail below, but the scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, if multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range.

[0038] (Resin Composition) The resin sheet of the present invention is formed from a resin composition containing polyvinyl acetal resin. Polyvinyl acetal resin has excellent flexibility, adhesion, and transparency, and a resin sheet containing polyvinyl acetal resin can easily satisfy the performance requirements of a laminated glass interlayer. In a preferred embodiment, the resin sheet of the present invention includes a melt-kneaded extruded resin sheet of the above resin composition.

[0039] Polyvinyl acetal resin is produced from polyvinyl alcohol resin and aldehydes by known methods. Polyvinyl alcohol resin can be obtained, for example, by polymerizing vinyl ester monomers and saponifying the resulting polymer.

[0040] The polyvinyl acetal resin used in the present invention preferably includes an α-olefin-modified polyvinyl acetal resin. An α-olefin-modified polyvinyl acetal resin refers to an acetalized product of an α-olefin-vinyl alcohol copolymer having α-olefin units in the main chain. An α-olefin-modified polyvinyl acetal resin can be obtained, for example, by acetalizing an aldehyde with a vinyl alcohol resin copolymerized with α-olefin (hereinafter referred to as an α-olefin vinyl alcohol copolymer) in the presence of an acidic catalyst. In this specification, a resin composition containing a polyvinyl acetal resin may be referred to as a "resin composition," and an α-olefin-modified polyvinyl acetal resin may be referred to as a "modified polyvinyl acetal resin."

[0041] Examples of α-olefin vinyl alcohol copolymers include those obtained by copolymerizing an α-olefin with a vinyl ester monomer and saponifying the resulting copolymer. Examples of α-olefins include ethylene, propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 4-methyl-1-pentene, vinylcyclohexane, and the like. Among these, ethylene is a preferred α-olefin.

[0042] Conventional methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization can be applied to copolymerize α-olefins and vinyl ester monomers. Depending on the polymerization method, azo initiators, peroxide initiators, redox initiators, etc., can be appropriately selected as polymerization initiators. For saponification reactions, conventional methods such as alcohol decomposition using alkaline or acid catalysts and hydrolysis can be applied, and among these, saponification reactions using methanol as a solvent and caustic soda (NaOH) as a catalyst are simple.

[0043] Although there is no particular limitation on the saponification degree of the α-olefin vinyl alcohol copolymer, it is preferably 95 mol% or more, more preferably 98 mol% or more, still more preferably 99 mol% or more, and even more preferably 99.9 mol% or more.

[0044] Examples of the vinyl ester monomer that serves as a raw material for the α-olefin vinyl alcohol copolymer include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, vinyl benzoate, etc. Among them, vinyl acetate is particularly preferred.

[0045] The content of the α-olefin unit in the α-olefin vinyl alcohol copolymer is, for example, 5 to 80 mol%, preferably 20 to 60 mol%, more preferably 25 to 50 mol%, still more preferably 30 to 46 mol%, and even more preferably 35 to 42 mol%. By satisfying this range, the α-olefin unit of the modified polyvinyl acetal resin described later can be adjusted to a suitable range.

[0046] The melt mass flow rate (MFR) of the α-olefin vinyl alcohol copolymer at 190 °C and a load of 2.16 kg is, for example, 0.1 to 50 g / 10 min, preferably 1 to 20 g / 10 min, more preferably 5 to 10 g / 10 min, and in one form, 3 to 8 g / 10 min. By satisfying this range of the MFR, the MFR of the modified polyvinyl acetal resin and the resin composition described later can be adjusted to a suitable range. Incidentally, the MFR can be measured by a method conforming to JIS K7210-1:2014.

[0047] Although there is no particular limitation on the method for producing the modified polyvinyl acetal resin of the present invention, it can be produced by a known production method. For example, a method in which an aldehyde is added to an α-olefin vinyl alcohol copolymer solution under acidic conditions for an acetalization reaction, or a method in which an aldehyde is added to an α-olefin vinyl alcohol copolymer dispersion under acidic conditions for an acetalization reaction, etc. can be mentioned.

[0048] After neutralizing the reaction product obtained after the acetalization reaction with an alkali, washing with water and removing the solvent, the target modified polyvinyl acetal resin is obtained.

[0049] The solvent for producing the modified polyvinyl acetal resin is not particularly limited, and examples thereof include water, alcohols, dimethyl sulfoxide, and a mixed solvent of water and alcohols.

[0050] The dispersion medium for producing the modified polyvinyl acetal resin is not particularly limited, and examples thereof include water and alcohol.

[0051] The catalyst for the acetalization reaction is not particularly limited, and either an organic acid or an inorganic acid may be used. Examples thereof include acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, hydrochloric acid, carbonic acid, etc. In particular, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid are preferably used because the washing after the reaction is easy.

[0052] The aldehyde used in the acetalization reaction is not particularly limited and includes, for example, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexylaldehyde, benzaldehyde, isobutyraldehyde, 2-ethylhexylaldehyde, 2-methylbutyraldehyde, trimethylacetaldehyde, 2-methylpentylaldehyde, 2,2-dimethylbutyraldehyde, 2-ethylbutyraldehyde, 3,5,5-trimethylhexylaldehyde, 7-octenal, citral, citronellal, and acro Examples of aldehydes used include lein, crotonaldehyde, 2,3,4-trihydroxybenzaldehyde, 3,4,5-trihydroxybenzaldehyde, 2,4,5-trihydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 2,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, 3-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, and 5-hydroxybenzaldehyde. In terms of heat resistance and optical properties, butyraldehyde, benzaldehyde, and isobutylaldehyde are preferred. These aldehydes may be used individually or in combination of two or more.

[0053] The alkali used to neutralize the reaction product is not particularly limited and includes, for example, sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium carbonate, sodium bicarbonate, potassium carbonate, and the like.

[0054] The α-olefin unit content of the modified polyvinyl acetal resin used in the present invention is, for example, 5 to 80 mol%, preferably 20 to 60 mol%, more preferably 25 to 50 mol%, even more preferably 30 to 46 mol%, even more preferably 35 to 42 mol%, and in one embodiment, 38 to 44 mol%. If the above percentage of α-olefin units is less than 5 mol%, the impact resistance and heat and moisture resistance of the modified polyvinyl acetal resin used in the present invention tend to decrease, and if it exceeds 80 mol%, the heat resistance tends to be impaired.

[0055] The vinyl alcohol unit content of the modified polyvinyl acetal resin used in the present invention is, for example, 20 to 70 mol%, preferably 25 to 55 mol%, more preferably 35 to 45 mol%, even more preferably 38 to 43 mol%, and in one embodiment, 34 to 43 mol%, based on the total monomer units constituting the resin. If the aforementioned proportion of vinyl alcohol units is less than 20 mol%, heat resistance and adhesiveness tend to deteriorate. On the other hand, if the aforementioned proportion of vinyl alcohol units is 70 mol% or more, coloring tends to deteriorate.

[0056] The acetal units in the modified polyvinyl acetal resin used in the present invention represent acetalized vinyl alcohol units, and are, for example, 5 to 50 mol%, preferably 10 to 35 mol%, more preferably 15 to 25 mol%, and even more preferably 18 to 22 mol%. If the acetal unit content is less than 5 mol%, the modified polyvinyl acetal resin used in the present invention tends to have high crystallinity, which can lead to poor transparency. Furthermore, if the acetal unit content is 50 mol% or more, heat resistance and glass adhesion tend to be impaired.

[0057] The MFR of the modified polyvinyl acetal resin used in the present invention at 140°C and a 21.6 kg load is, for example, 0.1 to 30 g / 10 min, preferably 5 to 25 g / 10 min, and more preferably 10 to 20 g / 10 min. By satisfying this range of MFR, the MFR of the resin composition described later can be adjusted to a suitable range.

[0058] (Compounds having a structure in which a hydrocarbon group Z having 6 or more carbon atoms is bonded to a polyoxyalkylene group) The resin composition used in the present invention preferably contains a compound having a structure in which a hydrocarbon group Z having 6 or more carbon atoms is bonded to a polyoxyalkylene group. The polyoxyalkylene group referred to herein has a structure represented by the formula -(AO)n- [wherein A is an alkylene group and n is an integer]. In this specification, "polyoxyalkylene" may be written as "POA".

[0059] The number of carbon atoms in the alkylene A of the POA group is, for example, 2 to 4, preferably 2. Specific examples of alkylene A include ethylene, propylene, and butylene. Among these, ethylene is the preferred alkylene A. The average number of repeats n of the oxyalkylene group AO is, for example, 1 to 30, preferably 1 to 20, more preferably 1 to 15, even more preferably 2 to 9, and even more preferably 3 to 7. If n is outside the above range, the balance between hydrophilicity and hydrophobicity becomes poor, and the compatibility between the POA alkyl ether and the modified polyvinyl acetal resin tends to decrease.

[0060] The hydrocarbon group is thought to have low polarity and exhibit affinity with the poly-α-olefin portion of the modified polyvinyl acetal resin. The POA group is thought to have high polarity and exhibit affinity with the acetal group and hydroxyl group of the modified polyvinyl acetal resin. Furthermore, it is thought that the compound exhibits excellent compatibility with the modified polyvinyl acetal resin due to the bonding of the hydrocarbon group and the POA group. Compounds with this structure exhibit a plasticizing effect on the modified polyvinyl acetal resin. Therefore, by including the compound as a plasticizer in the modified polyvinyl acetal resin composition, the puncture resistance of the laminated glass interlayer and laminated glass is improved.

[0061] In a preferred embodiment, the compound comprises a POA alkyl ether in which a hydrocarbon group Z having 6 or more carbon atoms and a POA group are linked by an ether bond. That is, the POA alkyl ether referred to herein preferably has a structure in which an alkylene oxide AO [wherein A is an alkylene group] is added to a monohydric or polyhydric alcohol Z[-OH]x [wherein Z is a hydrocarbon group and x is the valence of the alcohol].

[0062] In such cases, the valency x of the alcohol is, for example, 1 to 12, preferably 1 to 6, more preferably 1 to 3, and even more preferably 1. As x increases, hydrophilicity increases and compatibility with the resin tends to decrease.

[0063] The number of carbon atoms in the hydrocarbon group Z is, for example, 6 or more, preferably 6 to 30, more preferably 8 to 22, even more preferably 10 to 20, and even more preferably 12 to 14. When the number of carbon atoms of Z is within the above range, the affinity with the polyolefin and butyral portions of the modified polyvinyl acetal resin is further improved. If Z is less than 6, hydrophilicity increases and compatibility with the resin tends to decrease.

[0064] Examples of hydrocarbon groups include aliphatic, aromatic, and alicyclic hydrocarbons. The hydrocarbon groups may be saturated or unsaturated, but saturated hydrocarbon groups are preferred due to their resistance to discoloration and plasticizing properties. Examples of aliphatic hydrocarbon groups include linear or branched alkyl groups having the aforementioned range of carbon atoms. A compound consisting of one of the aforementioned structures may be used, or two or more may be used in combination.

[0065] In one preferred embodiment, the alcohol is a secondary alcohol. In this case, the hydrocarbon group Z includes a branched alkyl group.

[0066] In one preferred embodiment, the POA alkyl ether has a structure represented by the following formula.

[0067] Z-[O-(AO)n-H]x... (I)

[0068] In formula (I), Z is a linear or branched alkyl group having 6 or more carbon atoms, x is an integer from 1 to 12, AO is an oxyalkylene group having 2 to 4 carbon atoms, and n is an integer from 1 to 30.

[0069] The compound is preferably present in an amount of 5 to 40 parts by mass per 100 parts by mass of polyvinyl acetal resin. If the compound content is less than 5 parts by mass, the penetration resistance of the laminated glass tends to decrease, and if it exceeds 40 parts by mass, the edge delamination resistance of the laminated glass tends to decrease, and it also tends to bleed out more easily. The compound content is preferably 8 to 25 parts by mass, more preferably 10 to 22 parts by mass, even more preferably 12 to 19 parts by mass, even more preferably 14 to 17 parts by mass, and in one embodiment 15 to 20 parts by mass per 100 parts by mass of polyvinyl acetal resin.

[0070] (Other components) The resin composition used in the present invention may contain other thermoplastic resins in addition to polyvinyl acetal resin and the compound. The other thermoplastic resins are not particularly limited, but examples include (meth)acrylic resins and ionomer resins.

[0071] If the resin composition contains the other thermoplastic resins mentioned above, the content thereof is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on the total mass of the resin composition. If the content of other thermoplastic resins in the resin composition exceeds 20% by mass, the transparency, impact resistance, and adhesion to substrates such as glass tend to decrease.

[0072] The resin composition used in the present invention may further contain, as necessary, additives such as a second plasticizer, antioxidant, ultraviolet absorber, adhesion improver, blocking inhibitor, silane coupling agent, pigment, dye, and functional inorganic compound. Alternatively, if necessary, the content of plasticizers and various additives may be reduced by extraction or washing, and then the plasticizers and various additives may be added again.

[0073] When the resin composition contains the above-mentioned additives, the content thereof is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total mass of the resin composition. If the content of various additives exceeds 20% by mass, problems such as insufficient self-supporting properties (heat resistance) under high-temperature conditions and bleeding when used for a long period of time as a laminated glass interlayer tend to occur.

[0074] In particular, because the second plasticizer has a high effect of reducing self-supporting properties (heat resistance) under high-temperature conditions due to its properties, its content is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass, and even more preferably 0 to 0.1% by mass, relative to the total mass of the resin composition.

[0075] The second plasticizer is not particularly limited, but examples include triethylene glycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylhexanoate, di-(2-butoxyethyl)-adipate (DBEA), di-(2-butoxyethyl)-sebacate (DBES), di-(2-butoxyethyl)-azelaic acid, di-(2-butoxyethyl)-glutarate, di-(2-butoxyethoxyethyl)-adipate (DBEEA), di-(2-butoxyethoxyethyl)-sebacate (DBEES), di-(2-butoxyethoxyethyl)-azelaic acid, di-(2-butoxyethoxyethyl) Examples include di(2-2-hexoxyethyl)-glutarate, di(2-2-hexoxyethyl)-adipate, di(2-2-hexoxyethyl)-sebacate, di(2-2-hexoxyethyl)-azelaic acid, di(2-2-hexoxyethyl)-glutarate, di(2-2-hexoxyethoxyethyl)-adipate, di(2-2-hexoxyethoxyethyl)-sebacate, di(2-2-hexoxyethoxyethyl)-azelaic acid, di(2-2-hexoxyethoxyethyl)-glutarate, di(2-2-butoxyethyl)-phthalate and / or di(2-butoxyethoxyethyl)-phthalate. Among these, it is preferable that the plasticizer has a sum of 28 or more carbon atoms and oxygen atoms in its molecule. Examples include triethylene glycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylhexanoate, di-(2-butoxyethoxyethyl)-adipate, and di-(2-butoxyethoxyethyl)-sebacate. The above plasticizers may be used individually or in combination of two or more.

[0076] Furthermore, the resin composition may contain an antioxidant. Examples of antioxidants that can be used include phenolic antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Among these, phenolic antioxidants are preferred, and alkyl-substituted phenolic antioxidants are more preferred.

[0077] Examples of phenolic antioxidants include acrylate compounds such as 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate or 2,4-di-t-amyl-6-(1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl)phenyl acrylate, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, octadecyl-3-(3,5-)di-t-butyl-4-hydroxyphenyl)propionate, and 2,2 '-Methylene-bis(4-methyl-6-t-butylphenol), 4,4'-Butylidene-bis(4-methyl-6-t-butylphenol), 4,4'-Butylidene-bis(6-t-butyl-m-cresol), 4,4'-Thiobis(3-methyl-6-t-butylphenol), bis(3-cyclohexyl-2-hydroxy-5-methylphenyl)methane, 3,9-bis(2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8,10-tetra Oxaspiro[5,5]undecane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-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 or alkyl-substituted phenol compounds such as triethylene glycol bis(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate), 6-( Examples include triazine group-containing phenolic compounds such as 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-1,3,5-triazine, 6-(4-hydroxy-3-methyl-5-t-butylanilino)-2,4-bis-octylthio-1,3,5-triazine, or 2-octylthio-4,6-bis-(3,5-di-t-butyl-4-oxyanilino)-1,3,5-triazine.

[0078] Examples of phosphorus-based antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, tris(dinonylphenyl) phosphite, tris(2-t-butyl-4-methylphenyl) phosphite, tris(cyclohexylphenyl) phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, or These include monophosphite compounds such as 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, and diphosphite compounds such as 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis(phenyl-dialkyl(C12-C15) phosphite), 4,4'-isopropylidene-bis(diphenylmonoalkyl(C12-C15) phosphite), 1,1,3-tris(2-methyl-4-di-tridecyl phosphite-5-t-butylphenyl)butane or tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphite. Among these, monophosphite compounds are preferred.

[0079] Examples of sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, laurylstearyl 3,3'-thiodipropionate, pentaerythritol-tetrakis-(β-lauryl-thiopropionate), and 3,9-bis(2-dodecylthioethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane.

[0080] These antioxidants can be used individually or in combination of two or more. The amount of antioxidant added is preferably 0.001 to 5 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of polyvinyl acetal resin. These antioxidants may be added when manufacturing the modified polyvinyl acetal resin used in the present invention. Alternatively, they may be added to the resin composition when molding the resin sheet of the present invention.

[0081] Furthermore, the resin composition may also contain an ultraviolet absorber. Examples of ultraviolet absorbers used include benzotriazole-based ultraviolet absorbers such as 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, or 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, and 2,2,6,6-tetramethyl-4-pipet Examples include hindered amine-based UV absorbers such as lysyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate or 4-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)-1-(2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl)-2,2,6,6-tetramethylpiperidine, and benzoate-based UV absorbers such as 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate or hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate. The amount of these UV absorbers added is preferably 10 to 50,000 ppm by mass relative to the polyvinyl acetal resin, and more preferably in the range of 100 to 10,000 ppm. These UV absorbers can be used individually or in combination of two or more. These UV absorbers may be added when manufacturing the polyvinyl acetal resin used in the present invention. Alternatively, they may be added to the resin composition when molding the resin sheet of the present invention.

[0082] Furthermore, the resin composition may contain an adhesion modifier. Examples of adhesion modifiers used include those disclosed in WO03 / 033583A1, with alkali metal salts and / or alkaline earth metal salts of organic acids being preferred, particularly potassium acetate and / or magnesium acetate. Other additives, such as silane coupling agents, may also be added. The optimal amount of adhesion modifier varies depending on the additive used and the location where the resulting module or laminated glass will be used. However, it is generally preferable to adjust the adhesion strength of the resulting sheet to glass so that it is between 3 and 10 in the Pummel test (described in WO03 / 033583A1, etc.). It is particularly preferable to adjust it to 3 to 6 when high penetration resistance is required, and to 7 to 10 when high glass shatter resistance is required. When high glass shatter resistance is required, omitting the adhesion modifier is also a useful method.

[0083] Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyldiethoxysilane, and N-(2-aminoethyl)-3-aminopropyldiethoxysilane.

[0084] These silane coupling agents can be used individually or in combination of two or more. The amount of silane coupling agent is preferably 0.001 to 5 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of polyvinyl acetal resin. These silane coupling agents may be added when manufacturing the modified polyvinyl acetal resin used in the present invention. Alternatively, they may be added to the resin composition when molding the resin sheet of the present invention.

[0085] The resin composition used in the present invention can be manufactured by appropriately selecting the above components and mixing them by a commonly used method that is known in itself.

[0086] The MFR of the resin composition at 140°C and a 21.6 kg load is, for example, 1 to 50 g / 10 min, preferably 3 to 30 g / 10 min, and more preferably 10 to 20 g / 10 min. If the MFR is less than 1 g / 10 min, sufficient processability (fluidity) cannot be obtained within the appropriate molding temperature range during molding, requiring an increase in the molding temperature, and as a result, the resulting molded article tends to be easily discolored. If the MFR exceeds 50 g / 10 min, sufficient melt tension cannot be obtained within the appropriate molding temperature range during molding, and problems such as deterioration of film formation stability and surface texture of the molded article tend to occur.

[0087] (Resin Sheet) The thickness of the resin sheet of the present invention is not particularly limited, but is preferably 100 to 3,000 μm, more preferably 400 to 2,500 μm, even more preferably 700 to 1,500 μm, and even more preferably 800 to 1,000 μm, and may be, for example, 900 μm. If the resin sheet is thinner than 100 μm, it tends to be difficult to satisfy the penetration resistance performance of the laminated glass, and if it is thicker than 3,000 μm, the cost of the sheet itself is high and the cycle time of the lamination process tends to be long, which is undesirable. The thickness of the resin sheet is the average value (d) obtained by measuring a sheet sample of 300 mm in the TD direction × 300 mm in the MD direction using a dial gauge type thickness gauge at 10 mm intervals in the TD direction and MD direction, as described in the examples. The resin sheet may be used as a single molded sheet, or two or more molded sheets can be stacked to adjust to the desired thickness.

[0088] The resin sheet of the present invention is a resin sheet with excellent heat resistance. Therefore, the storage modulus E'(140) of the resin sheet of the present invention, under measurement conditions of a temperature of 140°C and a frequency of 1 Hz, is 0.4 to 7.0 MPa, preferably 1.0 to 4.0 MPa, more preferably 1.5 to 3.0 MPa, and in one embodiment, 0.5 to 2.5 MPa. By having the E'(140) of the resin sheet within the above range, changes in shape and dimensions can be minimized when the resin sheet is used in high-temperature regions.

[0089] The resin sheet of the present invention has a storage modulus E'(50) of preferably 20.0 to 600.0 MPa, more preferably 30.0 to 200.0 MPa, even more preferably 60.0 to 100.0 MPa, and in one embodiment, 20.0 to 84.0 MPa, under measurement conditions of a temperature of 50°C and a frequency of 1 Hz. When the E'(50) of the resin sheet is 20.0 MPa or higher, the storage stability of the sheet roll is improved even under normal conditions, and when it is 600.0 MPa or lower, the penetration resistance of the laminated glass is improved, and the handling of the resin sheet is improved, such as when cracking occurs during transport such as when winding or post-processing.

[0090] The resin sheet of the present invention has a storage modulus E'(70) of preferably 9.0 to 50.0 MPa, more preferably 12.0 to 30.0 MPa, even more preferably 14.0 to 20.0 MPa, and in one embodiment 9.0 to 19.5 MPa, under measurement conditions of a temperature of 70°C and a frequency of 1 Hz. When the E'(70) of the resin sheet is 9.0 MPa or higher, the storage stability of the sheet roll is improved even in high-temperature environments, and when it is 50.0 MPa or lower, adhesion to the casting drum during molding and elongation between the casting drum and the conveyor roll can be suppressed, thereby improving the quality of the resin sheet.

[0091] The resin sheet of the present invention preferably has a storage modulus E'(100) of 2.0 to 20.0 MPa, more preferably 4.0 to 15.0 MPa, even more preferably 6.0 to 12.0 MPa, and in one embodiment, 2.0 to 10.0 MPa, under measurement conditions of a temperature of 100°C and a frequency of 1 Hz. When the E'(100) of the resin sheet is 2.0 MPa or higher, the occurrence of wrinkles is suppressed when the sheet is molded by applying heat, and thickness unevenness of the resulting molded body is suppressed. When the E'(100) of the resin sheet is 20.0 MPa or lower, damage to the sheet is suppressed when the sheet is molded by applying heat, and it becomes easier to maintain shapeability for molds with complex shapes.

[0092] The resin sheet of the present invention has minimal thickness variation and excellent flatness. Because of its excellent flatness, when sandwiched between glass as an interlayer in laminated glass, the surface shape of the resin sheet can conform to the surface shape of the glass. Therefore, there is no need to correct the convex shape of the resin sheet surface by compression and plastic deformation with the glass, and optical distortion is not formed inside the laminated glass interlayer. Furthermore, because the resin sheet with excellent flatness does not amplify thickness variations even when multiple sheets are stacked, gauge bands are less likely to occur on the roll body wound from the resin sheet.

[0093] The resin sheet of the present invention has a thickness unevenness of 20.0% or less, for example, 12.5% ​​or less, preferably 12.0% or less, more preferably 8.0% or less, even more preferably 6.6% or less, even more preferably 5.0% or less, especially preferably 4.0% or less, and particularly preferably 3.0% or less. Thickness unevenness refers to the difference between the maximum thickness and minimum thickness of the resin sheet, expressed as a percentage of the average thickness. The thickness unevenness of the resin sheet can be determined by cutting a sheet sample obtained by cutting the resin sheet from the center in the TD direction to a size of 300 mm in the TD direction × 300 mm in the MD direction, and measuring it at 10 mm intervals in the TD and MD directions using a dial gauge type thickness gauge. The formula for calculating the thickness unevenness from the obtained measured values ​​is shown below.

[0094] Thickness variation (%) = ((dmax - dmin) / d) × 100

[0095] In the formula, dmax is the maximum value of the measured thickness of the resin sheet, dmin is the minimum value of the measured thickness of the resin sheet, and d is the average value of the measured thickness of the resin sheet. The thickness variation of the resin sheet can be determined in more detail according to the measurement conditions described in the examples.

[0096] The MD direction (MD is an abbreviation for Machine Direction) corresponds to the longitudinal direction of the sheet raw material during sheet manufacturing. The TD direction (TD is an abbreviation for Transverse Direction) corresponds to the width direction of the sheet raw material during sheet manufacturing. The same applies hereafter.

[0097] The resin sheet of the present invention, when a 900 μm thick resin sheet that has not been subjected to water absorption is measured at a measurement temperature of 20°C, has a haze of, for example, 1.5% or less, preferably 0.7% or less, more preferably 0.55% or less, even more preferably 0.5% or less, even more preferably 0.45% or less, and particularly preferably 0.39% or less. When the haze is within the above range, the transparency is further improved. Since the transparency of the resin sheet increases as the haze is smaller, the lower limit is not particularly limited and may be, for example, 0.01% or more. In this specification, the haze of the resin sheet is measured using a haze meter under conditions compliant with JIS K7136:2000.

[0098] Furthermore, the resin sheet of the present invention is obtained by immersing a 900 μm thick resin sheet in water at 25°C for 300 hours, leaving it for 24 hours under conditions of a temperature of 23°C and a 50% RH atmosphere, and then measuring the haze at a measurement temperature of 20°C, which is, for example, 5.0% or less, preferably 4.5% or less, more preferably 3.5% or less, and even more preferably 2.5% or less. When the haze is within the above range, the moisture resistance is good.

[0099] The resin sheets may have surface irregularities to prevent them from sticking together and to improve degassing during the lamination process. Conventional methods can be used to create these irregularities, such as creating a melt fracture structure by adjusting the extrusion conditions, or creating an embossed structure on the extruded sheet. Conventional methods can be used for the depth and shape of the embossing.

[0100] (Method for Manufacturing Resin Sheets) The resin sheets of the present invention are manufactured using a melt-kneading extrusion method. Specifically, first, polyvinyl acetal resin, a plasticizer, and additives, if necessary, are supplied to the extruder. At this time, the polyvinyl acetal resin and other additives such as plasticizers may be supplied simultaneously from the raw material inlet, or they may be supplied separately from different inlets with a time difference, taking into consideration the differences in usage and properties. When supplying the raw materials, it is preferable to blow in an inert gas from the raw material inlet to prevent the raw materials from coming into contact with oxygen.

[0101] Recycled materials may be used as at least part of the raw materials. This makes it possible to obtain a resin sheet containing recycled materials, which is a preferred embodiment of the present invention. Recycled materials refer to recycled materials recovered in the process of manufacturing the resin sheet of the present invention. Specifically, examples include sheet scraps, sheet edges, and other non-product parts generated in the process of manufacturing the sheet of the present invention; off-spec products; etc., which can be crushed and used as needed.

[0102] By including recovered raw materials, resource conservation is achieved, and the fusion of raw materials is reduced during the process leading up to their entry into the extruder. This leads to greater dispersion of the raw materials, improving extrusion stability during film formation. As a result, variations in the thickness of the resulting resin sheets are suppressed, improving the quality of the resin sheets and enhancing moldability and post-processing capabilities.

[0103] The content of recovered raw materials in the resin sheet of the present invention may be 1 to 100% by mass, 10 to 90% by mass, 20 to 80% by mass, or 30 to 70% by mass.

[0104] The raw materials supplied to the extruder are kneaded and melted to form a resin composition. This resin composition has the heat resistance required for the resin sheet of the present invention and exhibits a predetermined storage modulus E'.

[0105] The temperature of the resin composition during melt mixing is adjusted to, for example, 120 to 230°C, preferably 130 to 200°C, and more preferably 140 to 180°C. If the melt mixing temperature is too high, the polyvinyl acetal resin will decompose, and the content of volatile substances will increase. Conversely, if the melt mixing temperature is too low, the content of volatile substances will also increase. In order to efficiently remove volatile substances, it is preferable to remove them by reducing the pressure from the vent port of the extruder.

[0106] Thorough melt-mixing should be carried out. This allows plasticizers and other substances to be uniformly dispersed in the resin composition. For example, by using a twin-screw extruder, increasing the screw rotation speed, and mixing for a long time, sufficient energy can be imparted to the resin composition. The energy required per unit weight of the melt-mixed material is called the specific energy, and it can be calculated from the power consumption of the extruder. For example, the power consumption (kW) and extrusion rate (kg / h) per hour are measured during steady-state operation of the extruder. From the obtained measurements, the specific energy of melt-mixing (kWh / kg) can be determined using the following formula.

[0107] Specific energy [kWh / kg] = Motor power [kW] / Extrusion rate [kg / h]

[0108] The specific energy of the melt kneading process is adjusted to, for example, 0.05 kWh / kg or more, preferably 0.10 kWh / kg or more, more preferably 0.15 kWh / kg or more, and even more preferably 0.20 kWh / kg or more. This improves the transparency and moisture resistance of the resulting resin sheet, reduces thickness variations, and shrinks the gauge band of the roll body. The kneading process is controlled by controlling the variation in the extrusion amount using a gear pump, and the resin pressure fluctuation range at the gear pump outlet is adjusted to preferably ±20% or less, more preferably ±15% or less, even more preferably ±10% or less, and even more preferably ±5% or less. This further enhances the aforementioned advantages.

[0109] Next, the molten and kneaded resin composition is extruded from the die into a sheet. For example, a T-die is used, which has a lip spacing corresponding to the desired thickness of the resin sheet and a width dimension corresponding to the desired width of the resin sheet.

[0110] The sheet-like molten mixture extruded from the die is then brought into contact with a casting drum to cool and solidify, forming it into a sheet.

[0111] The temperature of the casting drum is adjusted to, for example, 10 to 120°C, preferably 20 to 90°C, and more preferably 25 to 60°C. If the temperature of the casting drum is below 10°C, the molten mixture does not adhere well to the metal casting rolls, resulting in optical distortion, thicker variations, and poor haze. Conversely, if the temperature of the casting drum exceeds 120°C, the molten mixture adheres too closely to the metal casting rolls, resulting in optical distortion, thicker variations, and poor haze.

[0112] (Laminated Glass Interlayer) The resin sheet of the present invention is useful as a laminated glass interlayer. This laminated glass interlayer is particularly preferred as an interlayer for laminated glass used as a structural material due to its excellent adhesion to substrates such as glass, transparency, and self-supporting properties. Furthermore, it is suitable not only as an interlayer for laminated glass used as a structural material, but also as an interlayer for laminated glass used in various applications such as mobile bodies such as automobiles, buildings, and solar cells. In addition, due to its adhesion to various substrates, it is also useful as an adhesive or interlayer adhesive sheet for paper, wood, and plastics, as well as a protective sheet for glass surfaces, but its applications are not limited to these.

[0113] (Laminated Glass) Laminated glass can be produced by inserting and laminating the resin sheet of the present invention between two or more sheets of glass made of inorganic or organic glass. There are no particular restrictions on the glass to be laminated with the laminated glass interlayer of the present invention, but in addition to inorganic glass such as float glass, tempered glass, wired glass, and heat-absorbing glass, conventionally known organic glass such as polymethyl methacrylate and polycarbonate can be used. There are no particular restrictions on the thickness of the glass, but 1 to 10 mm is preferred, and 2 to 6 mm is more preferred.

[0114] The interlayer used in the laminated glass of the present invention may consist only of a layer (x) containing the above-mentioned polyvinyl acetal resin or resin composition, or it may be a multilayer film containing at least one layer (x). The multilayer film is not particularly limited, but examples include a two-layer film in which layer (x) and other layers are laminated, and a three-layer film in which other layers are arranged between two layers (x). The thickness of layer (x) is preferably 100 to 3,000 μm, more preferably 400 to 2,500 μm, even more preferably 700 to 1,500 μm, and for example, even more preferably 900 μm.

[0115] Other layers include layers containing known resins. Examples of such resins include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polytetrafluoroethylene, acrylic resin, polyamide, polyacetal, polycarbonate, polyethylene terephthalate and polybutylene terephthalate among polyesters, cyclic polyolefin, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, liquid crystal polymer, and polyimide. The other layers may also contain additives such as plasticizers, antioxidants, ultraviolet absorbers, light stabilizers, antiblocking agents, pigments, dyes, heat-shielding materials (e.g., inorganic or organic heat-shielding materials with infrared absorption capabilities), and functional inorganic compounds, as needed.

[0116] The lamination method for obtaining the above-mentioned laminated glass can be any known method, such as using a vacuum laminator, a vacuum bag, a vacuum ring, or a nip roll. Additionally, a method of immersing the glass in an autoclave after temporary bonding can also be performed.

[0117] When using a nip roll, for example, one method is to perform the first temporary bonding at a temperature below the flow initiation temperature of the resin composition, and then perform another temporary bonding under conditions close to the flow initiation temperature. Specifically, for example, one method is to heat to 30 to 70°C with an infrared heater, then degas with a roll, and then heat again to 50 to 120°C before pressing and bonding or temporary bonding with a roll.

[0118] The autoclave process, which is performed as an additional step after the initial bonding, is carried out for approximately 2 hours at a temperature of 130 to 150°C under a pressure of approximately 1 to 1.5 MPa, although this varies depending on the thickness and configuration of the module and laminated glass.

[0119] The laminated glass of the present invention preferably exhibits excellent transparency. For example, the haze of laminated glass formed from a 900 μm thick resin sheet of the present invention with an unwater-absorbed interlayer, measured at a measurement temperature of 20°C, is preferably 1.5% or less, more preferably 0.7% or less, even more preferably 0.5% or less, and even more preferably 0.39% or less. Furthermore, the haze of laminated glass formed from a resin sheet of the present invention with an interlayer immersed in 25°C water for 300 hours and left for 24 hours under conditions of a temperature of 23°C and a 50% RH atmosphere, measured at a measurement temperature of 20°C, is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 3.5% or less, and even more preferably 2.5% or less. In this specification, the haze of laminated glass is measured using a haze meter under conditions compliant with JIS K7136:2000.

[0120] Because the laminated glass of the present invention has excellent transparency, impact resistance, and heat resistance, it can be suitably used in automotive windshields, automotive side windows, automotive sunroofs, automotive rear windows, head-up display glass, laminates for facades, exterior walls and roofs, panels, doors, windows, walls, roofs, sunroofs, soundproof walls, display windows, balconies, railing walls and other building materials, partition glass members for conference rooms, solar panels, and the like.

[0121] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0122] <Example 1> (1) Synthesis of ethylene-modified polyvinyl butyral resin EVOH1 (MFR (190°C, 2.16 kg) 3.5 g / 10 min, ethylene unit content 38 mol%, degree of saponification 99.98 mol%), an ethylene vinyl alcohol copolymer (hereinafter referred to as "EVOH") synthesized by the method described in Patent No. 7354455, was dispersed in 377 parts by mass of water, and 20.0 parts by mass of isobutyraldehyde was added. The resulting dispersion was heated to 60°C under stirring. Stirring was continued for 2 hours to impregnate the EVOH with isobutyraldehyde. Then, at 60°C, 10 parts by mass of 1 M hydrochloric acid was added to the dispersion to carry out the butyralization reaction. 2 hours after the first addition of hydrochloric acid, 40 parts by mass of 1 M hydrochloric acid was added, and the butyralization reaction was carried out for a further 4 hours. The butyralized product produced by butyralization was in a solid state.

[0123] Subsequently, the butyralization reaction was stopped by neutralizing the dispersion with 75 parts by mass of 1 M sodium hydroxide. To neutralize the solid interior of the butyral, the dispersion was stirred at 60°C for a further 8 hours. The neutralized butyral was filtered off, and the butyral was washed by adding 500 parts by mass of deionized water and stirring at 60°C for 6 hours.

[0124] The butyral compound was filtered off, and 500 parts by mass of deionized water was added to the butyral compound. The mixture was stirred at 60°C for 6 hours to perform a second wash of the butyral compound. The wash water was filtered off, and vacuum drying was carried out at 60°C for 8 hours to obtain 113 parts by mass (100% yield) of pelletized ethylene-modified polyvinyl butyral resin (PVB1). The MFR of the resin (PVB1) was measured at 190°C and under a load of 2.16 kg using the method described above. The measurement results are shown in Table 1.

[0125] (2) A polyethylene glycol alkyl ether ("TERGITOL 15-S-5" (trade name), manufactured by Dow Chemical, hereinafter sometimes referred to as "EO5") was prepared in which Z is 12 to 14, x is 1, the number of carbon atoms in AO is 2, and n is 5 in the manufacturing formula (I) of the resin sheet. In this specification, "polyethylene glycol" may be written as "PEG". Also, "polyethylene glycol" is synonymous with "polyoxyethylene", and refers to a POA in which the alkylene group is an ethylene group.

[0126] A sheet was formed using 100 parts by mass of resin (PVB1) and 20 parts by mass of PEG alkyl ether (EO5) as follows. First, nitrogen purging was performed from the raw material inlet using 99.99% pure nitrogen adjusted to a flow rate of 4.0 L / min to prevent oxygen contamination from the outside. Then, PVB1 was added from the raw material inlet, and EO5 was added by dripping with a liquid pump (model number: NP-KX-500, manufactured by Nippon Precision Science Co., Ltd.) using a vented twin-screw compounding extruder "KZW48-45" (product name, manufactured by Technovel Co., Ltd., L / D: 45, bore diameter: 48 mmφ), adjusting the total extrusion rate to 70 kg / h.

[0127] The mixture was melt-kneaded for a sufficient amount of time in a twin-screw extruder at a cylinder temperature of 160°C and a screw rotation speed of 450 rpm. The extruder was operated steadily, and the power consumption (kW) and extrusion rate (kg / h) were measured. The specific energy (kWh / kg) of the melt-kneaded mixture was calculated from the obtained measurements. The calculation results are shown in Table 1.

[0128] Next, the outlet pressure of the gear pump (manufactured by Kyowa Finetech Co., Ltd., model number: HDD-45 / CDD-45) was adjusted to 2.0 MPa, and foreign matter was removed using a 200-mesh stainless steel filter. The molten mixture was then extruded into a sheet from a T-die (T-die width: 1,050 mm, gap thickness of the T-die lip: 1,000 μm), solidified on a casting drum (mirror-finish metal roll) maintained at a surface temperature of 40°C, and a resin sheet with a thickness of 900 μm and a width of 1,000 mm was formed. This sheet was then wound onto a 3-inch paper core to obtain a 50 m roll. The MFR of the obtained resin sheet was measured using the method described above under conditions of 140°C and a load of 21.6 kg. The measurement results are shown in Table 1.

[0129] (3) Characteristics of the resin sheet The characteristics of the obtained resin sheet were measured and evaluated as follows. The results are shown in Table 1.

[0130] [Thickness Variation] A resin sheet was cut from the center in the TD direction to a size of 300 mm in the TD direction x 300 mm in the MD direction to create a sheet sample. Thickness was measured at 10 mm intervals from both ends of the sheet sample in the TD direction and at 10 mm intervals from both ends in the MD direction using a dial gauge type thickness gauge (JIS B7503:2017 compliant, "PEACOCK® UPRIGHT DIAL GAUGE (graduation 0.001 mm, measurement range 2 mm, model No. 25, measuring probe 5 mmφ flat type)" manufactured by Ozaki Seisakusho Co., Ltd.) at 31 points in each direction in the TD direction and 31 points in each direction in the MD direction, for a total of 961 points.

[0131] The maximum (dmax), minimum (dmin), and average (d) values ​​of the measured values ​​were determined, and the thickness variation (%) was calculated using the aforementioned formula. Three measurements were taken, and the average of the resulting thickness variation (%) was calculated.

[0132] [Haze of Resin Sheet] A test specimen measuring 50 mm in the TD direction and 50 mm in the MD direction was cut from the center of the resin sheet in the TD direction to obtain a test specimen. The haze of the obtained test specimen was measured using a haze meter (Suga Test Instruments Co., Ltd. "HZ-1" (product name)) according to the method described above. A low haze value indicates that the resin sheet has excellent transparency. This measurement was performed while maintaining the temperature of the resin sheet at 20°C.

[0133] [Haze of Resin Sheet After Water Absorption] A test specimen measuring 50 mm in the TD direction and 50 mm in the MD direction was cut from the center of the resin sheet in the TD direction to obtain a test specimen. The obtained test specimen was immersed in water at 25°C for 300 hours, and then left for 24 hours under conditions of 23°C and 50% RH. The haze of the test specimen was measured using a haze meter (Suga Test Instruments Co., Ltd. "HZ-1" (product name)) according to the method described above. A low haze value indicates that the resin sheet has excellent transparency. This measurement was performed while maintaining the temperature of the resin sheet at 20°C. The following criteria were used for evaluation. An evaluation result of "S" is the best. An evaluation result of "A" or "B" indicates that the sheet has good haze after water absorption.

[0134] (Judgment Criteria) "S": Haze after water absorption is 2.5% or less "A": Haze after water absorption is 3.5% or less "B": Haze after water absorption is 4.5% or less "C": Haze after water absorption is greater than 4.5%

[0135] [Storage Modulus E'] A test specimen measuring 5 mm in the TD direction and 20 mm in the MD direction was cut from the center of the sheet in the TD direction to obtain a test specimen. Based on JIS K7244-1:1998, the storage modulus E' of the sheet at each temperature (50°C, 70°C, 100°C, 140°C) was determined using the Rheogel-E4000 dynamic viscoelasticity measuring device manufactured by UBM Co., Ltd.

[0136] Measurements were performed only in the MD direction of the sheet under the following conditions, and the average value of the results of three measurements was taken as the storage modulus E' of the sheet.

[0137] • Measurement method: Dynamic viscoelasticity measurement (sine wave) • Measurement mode: Temperature dependent • Chuck: Tensile • Waveform: Sine wave • Excitation type: Stop excitation • Chuck distance: 10 mm • Specimen width: 5 mm • Frequency: 1 Hz • Measurement temperature: -50°C to 180°C • Heating rate: 3°C / min • Measurement atmosphere: Under air

[0138] [Heat Resistance] Figure 1 is a schematic diagram showing the method for measuring the heat resistance of the sheet. First, the center 1 in the TD direction 4 of the sheet was defined, and with this as the center, the TD directions 4-1, 4-2, and 4-3 were divided into 25 mm, 50 mm, and 25 mm sections, respectively, and marked with an oil-based marker. A test piece 2 was cut out with a length of 30 mm from end to end in the MD direction 5. The test piece 2 was left for 24 hours under conditions of a temperature of 25°C and a 65% RH atmosphere without any load applied from above to regulate the humidity of the test piece 2.

[0139] Next, a support column 3 with a width 11 of 50 mm and a height 12 of 30 mm was prepared, double-sided tape was attached to its top surface, and the test piece 2 was attached to the support column 3 so that the sides and center 1 of the test piece 2 coincided with the sides and center of the support column 3.

[0140] The support column 3, to which sheet 2 was attached, was placed in a 150°C hot air oven for 4 minutes, then removed and left for more than 30 minutes under conditions of 23°C and 50% RH. After that, the difference between the height 8 of the support column and the heights of both ends of the sheet was determined as follows, and this was defined as the amount of deflection.

[0141] The height 6 at the right edge is defined as the height from the ground to the center 9 at the right edge in the MD direction, the height 7 at the left edge is defined as the height from the ground to the center 10 at the left edge in the MD direction, and the heights at both ends of the sheet are the average of the height 6 at the right edge and the height 7 at the left edge.

[0142] The heat resistance of the sheets was evaluated by comparing the amount of deflection before and after storage in an oven. The heat resistance was evaluated according to the following evaluation criteria. A result of "S" is the best. In addition, sheets with a result of "A" or "B" were judged to have good heat resistance.

[0143] (Judgment Criteria) "S": Deflection before and after storage in the oven is 1.0 mm or less "A": Deflection before and after storage in the oven is 1.5 mm or less "B": Deflection before and after storage in the oven is 2.0 mm or less "C": Deflection before and after storage in the oven exceeds 2.0 mm

[0144] [Gauge band of product roll] After manufacturing as described above and leaving the resulting roll body for 24 hours under conditions of a temperature of 23°C and a 50% RH atmosphere, the surface was visually inspected, and if a band-shaped convex portion extending in the circumferential direction was observed, the height of the convex portion was measured with a caliper, and a step of 2 μm or more was identified as a gauge band and evaluated as follows. A result of "S" is the best.

[0145] (Criteria for evaluation) "S": No gauge band "A": Gauge band of 2 μm or more but less than 5 μm is present "B": Gauge band of 5 μm or more is present

[0146] (4) A roll of laminated glass with a thickness of 900 μm, a width of 1,000 mm, and a length of 50 m was cut from the center of the TD direction of the surface layer, measuring 300 mm in the TD direction and 300 mm in the MD direction. This cut was sandwiched between two pieces of float glass with a thickness of 2.7 mm and placed in a vacuum laminator (Nisshinbo Mechatronics Co., Ltd., 1522N). The inside of the vacuum laminator was depressurized at 150°C for 1 minute. While maintaining the depressurized state and temperature, it was pressed at 30 kPa for 5 minutes to obtain a temporary bond. The obtained temporary bond was placed in an autoclave and treated at 150°C and 1.2 MPa for 30 minutes to obtain laminated glass. The thickness of the laminated glass interlayer was 900 μm.

[0147] (5) Characteristics of Laminated Glass The characteristics of the obtained laminated glass were measured and evaluated as follows. The results are shown in Table 1.

[0148] [Optical Distortion of Laminated Glass] The optical distortion of laminated glass was visually evaluated according to the following evaluation criteria using a distortion tester (model number SVP-10-II, manufactured by Toshiba Corporation). A result of "S" is the best. Furthermore, a result of "A" or higher was judged to be at a level that does not pose any problems in practical use.

[0149] (Judgment Criteria) "S": No noticeable polarization irregularities are visible on the surface of the laminated glass. "A": Minor polarization irregularities (such as streaky or irregular shapes) are visible. "B": More severe polarization irregularities (such as streaky or irregular shapes) are visible than in "A".

[0150] [Haze of Laminated Glass] The haze of the obtained test specimens was measured using a haze meter (HZ-1 (product name) manufactured by Suga Test Instruments Co., Ltd.) according to the method described above. A low haze value indicates that the laminated glass has excellent transparency. This measurement was performed while the temperature of the laminated glass was kept at 20°C.

[0151] [Haze of laminated glass using resin sheet after water absorption] A test specimen was obtained by cutting a 300 mm x 300 mm section from the center of the TD direction of the surface layer of a roll body with a thickness of 900 μm, a width of 1,000 mm, and a length of 50 m. The obtained test specimen was immersed in water at 25°C for 300 hours, and then left for 24 hours under conditions of 23°C and a 50% RH atmosphere. The test specimen was then sandwiched between two 2.7 mm thick float glass sheets and placed in a vacuum laminator (Nisshinbo Mechatronics Co., Ltd. 1522N), and the inside of the vacuum laminator was reduced in pressure at 150°C for 1 minute. A temporary bond was obtained by pressing at 30 kPa for 5 minutes while maintaining the reduced pressure and temperature. The obtained temporary bond was placed in an autoclave and treated at 150°C and 1.2 MPa for 30 minutes to obtain laminated glass. The thickness of the laminated glass interlayer was 900 μm.

[0152] The haze of the obtained laminated glass was measured using a haze meter (Suga Test Instruments Co., Ltd. "HZ-1" (product name)) according to the method described above. A low haze value indicates that the laminated glass has excellent transparency. This measurement was performed while maintaining the temperature of the laminated glass at 20°C. The results were judged based on the following criteria. A result of "S" is the best. A result of "A" or "B" indicates that the haze of the laminated glass after water absorption is good.

[0153] (Judgment Criteria) "S": Laminated glass haze is 2.5% or less "A": Laminated glass haze is 3.5% or less "B": Laminated glass haze is 4.5% or less "C": Laminated glass haze exceeds 5.0%

[0154] [Edge delamination resistance] After leaving the laminated glass in an atmosphere of 85°C-85% RH, the presence or absence of delamination between the interlayer and the glass at the periphery (edge) of the laminated glass was visually observed, and the edge delamination resistance was evaluated by the time until delamination occurred.

[0155] (Evaluation Criteria) S: No peeling after 2000 hours or more A: Peeling occurs between 300 hours and 2000 hours B: Peeling occurs in less than 300 hours

[0156] [Ball Drop Test (Penetration Resistance)] The edges of the laminated glass were fixed to a support frame and held horizontally. A 2.26 kg steel ball was then dropped from a predetermined height onto the center of the laminated glass test piece. The height at which the steel ball did not penetrate half of the laminated glass pieces was defined as the ball drop height, and the results were evaluated according to the following criteria. A result of S or A in the ball drop test indicates that the laminated glass has superior penetration resistance. This test was conducted while maintaining the temperature of the laminated glass at 23°C.

[0157] (Evaluation Criteria) S: 5m or more A: 1.5m or more but less than 5m B: Less than 1.5m

[0158] <Examples 2-6> Resin sheets and laminated glass were manufactured in the same manner as in Example 1, except that the molding conditions for the resin sheet were changed as shown in Table 1, and their properties were tested. The results are shown in Table 1.

[0159] <Example 7> Ethylene-modified polyvinyl butyral resin (PVB2) was synthesized in the same manner as in Example 1, except that 28.0 parts by mass of isobutyraldehyde was used instead of 20.0 parts by mass of isobutyraldehyde. The characteristic values ​​of the resin (PVB2) are shown in Table 1.

[0160] Resin compositions, resin sheets, and laminated glass were manufactured in the same manner as in Example 1, except that PVB2 was used instead of PVB1, and their properties were tested. The results are shown in Table 1.

[0161] <Example 8> Instead of using 100 parts by mass of EVOH1, 100 parts by mass of EVOH2 (MFR (190°C, 2.16 kg) 10 g / 10 min, ethylene unit content 44 mol%, degree of saponification 99.98 mol%) synthesized by the method described in Patent No. 7354455 was used, and 18.0 parts by mass of isobutyraldehyde was used instead of 20.0 parts by mass of isobutyraldehyde. Ethylene-modified polyvinyl butyral resin (PVB3) was synthesized in the same manner as in Example 1. The characteristic values ​​of the resin (PVB3) are shown in Table 1.

[0162] Resin compositions, resin sheets, and laminated glass were manufactured in the same manner as in Example 1, except that PVB3 was used instead of PVB1, and their properties were tested. The results are shown in Table 1.

[0163] <Example 9> As a recovered raw material, the resin sheet manufactured in Example 1 was crushed using a pulverizer, solidified using a granulator, and molded into pellets.

[0164] Resin sheets and laminated glass were manufactured in the same manner as in Example 1, except that a blend of 80 parts by mass of PVB1 and 20 parts by mass of the recovered raw material was used instead of 100 parts by mass of PVB1, and their properties were tested. The results are shown in Table 1.

[0165] <Example 10> (1) Synthesis of ethylene-modified polyvinyl butyral resin EVOH1 (MFR (190°C, 2.16 kg) 3.5 g / 10 min, ethylene unit content 38 mol%, degree of saponification 99.98 mol%), an ethylene vinyl alcohol copolymer (hereinafter referred to as "EVOH") synthesized by the method described in Patent No. 7354455, was dispersed in 377 parts by mass of water, and 20.0 parts by mass of isobutyraldehyde was added. The resulting dispersion was heated to 60°C under stirring. Stirring was continued for 2 hours to impregnate the EVOH with isobutyraldehyde. Then, at 60°C, 10 parts by mass of 1 M hydrochloric acid was added to the dispersion to carry out the butyralization reaction. 2 hours after the first addition of hydrochloric acid, 40 parts by mass of 1 M hydrochloric acid was added, and the butyralization reaction was carried out for a further 4 hours. The butyralized product produced by butyralization was in a solid state.

[0166] Subsequently, the butyralization reaction was stopped by neutralizing the dispersion with 75 parts by mass of 1 M sodium hydroxide. To neutralize the solid interior of the butyral, the dispersion was stirred at 60°C for a further 8 hours. The neutralized butyral was filtered off, and the butyral was washed by adding 500 parts by mass of deionized water and stirring at 60°C for 6 hours.

[0167] The butyral compound was filtered off, and 500 parts by mass of deionized water was added to the butyral compound. The mixture was stirred at 60°C for 6 hours to perform a second wash of the butyral compound. The wash water was filtered off, and vacuum drying was carried out at 60°C for 8 hours to obtain 113 parts by mass (100% yield) of pelletized ethylene-modified polyvinyl butyral resin (PVB1). The MFR of the resin (PVB1) was measured at 190°C and under a load of 2.16 kg using the method described above. The measurement results are shown in Table 1.

[0168] (2) A polyethylene glycol alkyl ether (Tergitol 15-S-7, a product name of Dow Chemical, hereinafter sometimes referred to as "EO7") was prepared in which Z is 12 to 14, x is 1, AO has 2 carbon atoms, and n is 7 in the manufacturing formula (I) of the resin sheet.

[0169] A sheet was formed using 100 parts by mass of resin (PVB1) and 20 parts by mass of PEG alkyl ether (EO7) as follows. First, nitrogen purging was performed from the raw material inlet using 99.99% pure nitrogen adjusted to a flow rate of 4.0 L / min to prevent oxygen contamination from the outside. Then, PVB1 was added from the raw material inlet, and EO7 was added by dripping with a liquid pump (model number: NP-KX-500, manufactured by Nippon Precision Science Co., Ltd.) using a vented twin-screw compounding extruder "KZW48-45" (product name, manufactured by Technovel Co., Ltd., L / D: 45, bore diameter: 48 mmφ), adjusting the total extrusion rate to 70 kg / h.

[0170] The mixture was melt-kneaded for a sufficient amount of time in a twin-screw extruder at a cylinder temperature of 160°C and a screw rotation speed of 450 rpm. The extruder was operated steadily, and the power consumption (kW) and extrusion rate (kg / h) were measured. The specific energy (kWh / kg) of the melt-kneaded mixture was calculated from the obtained measurements. The calculation results are shown in Table 1.

[0171] Next, the outlet pressure of the gear pump (manufactured by Kyowa Finetech Co., Ltd., model number: HDD-45 / CDD-45) was adjusted to 2.0 MPa, and foreign matter was removed using a 200-mesh stainless steel filter. The molten mixture was then extruded into a sheet from a T-die (T-die width: 1,050 mm, gap thickness of the T-die lip: 1,000 μm), solidified on a casting drum (mirror-finish metal roll) maintained at a surface temperature of 40°C, and a resin sheet with a thickness of 900 μm and a width of 1,000 mm was formed. This sheet was then wound onto a 3-inch paper core to obtain a 50 m roll. The MFR of the obtained resin sheet was measured using the method described above under conditions of 140°C and a load of 21.6 kg. The measurement results are shown in Table 1.

[0172] (3) Properties of the resin sheet The properties of the obtained resin sheet were measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0173] (4) A roll of laminated glass with a thickness of 900 μm, a width of 1,000 mm, and a length of 50 m was cut from the center of the TD direction of the surface layer, measuring 300 mm in the TD direction and 300 mm in the MD direction. This cut was sandwiched between two pieces of float glass with a thickness of 2.7 mm and placed in a vacuum laminator (Nisshinbo Mechatronics Co., Ltd., 1522N). The inside of the vacuum laminator was depressurized at 150°C for 1 minute. While maintaining the depressurized state and temperature, it was pressed at 30 kPa for 5 minutes to obtain a temporary bond. The obtained temporary bond was placed in an autoclave and treated at 150°C and 1.2 MPa for 30 minutes to obtain laminated glass. The thickness of the laminated glass interlayer was 900 μm.

[0174] (5) Characteristics of Laminated Glass The characteristics of the obtained laminated glass were measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0175] <Example 11> Resin sheets and laminated glass were manufactured in the same manner as in Example 10, except that 15 parts by mass of EO5 and 5 parts by mass of di-(2-butoxyethyl)-adipate ester (DBEA, manufactured by Tokyo Chemical Industry Co., Ltd.) were used instead of 20 parts by mass of EO7, and their properties were tested. The results are shown in Table 1.

[0176] <Example 12> A polyethylene glycol alkyl ether (product name "NONION EH-208" manufactured by NOF Corporation, hereinafter sometimes referred to as "EH-208") was prepared, in which Z is 8, x is 1, AO has 2 carbon atoms, and n is 8 in formula (I).

[0177] Resin sheets and laminated glass were manufactured and their properties tested in the same manner as in Example 10, except that 20 parts by mass of EH-208 were used instead of 20 parts by mass of EO7. The results are shown in Table 1.

[0178] <Comparative Example 1> 100 parts by mass of PVB1 and 20 parts by mass of di-(2-butoxyethyl)-adipate ester (DBEA, manufactured by Tokyo Chemical Industry Co., Ltd.) were melt-kneaded for 5 minutes at a chamber temperature of 160°C and a rotation speed of 60 rpm using a Laboplast Mill (product name "4M150" manufactured by Toyo Seiki Seisakusho Co., Ltd.). The contents of the chamber were removed and cooled to obtain a resin composition. The MFR of the obtained resin composition was measured by the above method under the conditions of 190°C and a load of 2.16 kg. The measurement results are shown in Table 1.

[0179] The resulting resin composition was heated at 180°C and subjected to a load of 50 kgf / cm². ２ A resin sheet with a thickness of 900 μm was obtained by compression molding at a pressure of 50 MPa for 5 minutes. The properties of the obtained resin sheet were measured as follows. The measurement results are shown in Table 1.

[0180] <Comparative Example 2> Resin sheets and laminated glass were manufactured in the same manner as in Comparative Example 1, except that "TERGITOL 15-S-5" manufactured by Dow Chemical Company was used instead of di-(2-butoxyethyl)-adipate ester (DBEA, manufactured by Tokyo Chemical Industry Co., Ltd.), and their properties were tested. The results are shown in Table 1.

[0181] <Comparative Example 3> Resin sheets and laminated glass were manufactured in the same manner as in Comparative Example 1, except that only 100 parts by mass of PVB1 was used, and their properties were tested. The results are shown in Table 1.

[0182] <Comparative Example 4> Polyvinyl butyral resin (PVB4) was synthesized in the same manner as in Example 1, except that 100 parts by mass of polyvinyl alcohol (MFR (190°C, 2.16 kg) 2 g / 10 min, degree of saponification 97 mol%) was used instead of 100 parts by mass of EVOH1, and 60.0 parts by mass of isobutyraldehyde was used instead of 20.0 parts by mass of isobutyraldehyde. The characteristic values ​​of the resin (PVB4) are shown in Table 1.

[0183] Resin sheets and laminated glass were manufactured in the same manner as in Comparative Example 1, except that PVB4 was used instead of PVB1, and their properties were tested. The results are shown in Table 1.

[0184]

[0185]

[0186]

[0187] 1...Center, 2...Test specimen, 3...Support column, 4...TD direction, 5...MD direction, 6...Height of the right end, 7...Height of the left end, 8...Height of the support column, 9...Center of the right end, 10...Center of the left end, 11...Width of the support column, 12...Length of the support column.

Claims

1. A resin sheet containing polyvinyl acetal resin, having a storage modulus E'(140) at 140°C of 0.4 to 7.0 MPa, and a thickness variation of 20.0% or less.

2. The resin sheet according to claim 1, wherein the storage modulus E'(50) at 50°C is 20.0 to 600.0 MPa.

3. The resin sheet according to claim 1, wherein the storage modulus E'(70) at 70°C is 9.0 to 50.0 MPa.

4. The resin sheet according to claim 1, wherein the storage modulus E'(100) at 100°C is 2.0 to 20.0 MPa.

5. The resin sheet according to claim 1, wherein the haze of the resin sheet having a thickness of 900 μm is 1.5% or less when measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000.

6. The resin sheet according to claim 1, wherein the resin sheet having a thickness of 900 μm is immersed in water at 25°C for 300 hours, left for 24 hours under conditions of a temperature of 23°C and a 50% RH atmosphere, and the haze measured at a measurement temperature of 20°C under conditions compliant with JIS K7136:2000 is 5.0% or less.

7. The resin sheet according to claim 1, comprising recovered raw materials.

8. The resin sheet according to claim 1, comprising a compound having a structure in which a hydrocarbon group having 6 or more carbon atoms is bonded to a polyoxyalkylene group.

9. The resin sheet according to claim 8, wherein the compound is contained in 5 to 40 parts by mass per 100 parts by mass of polyvinyl acetal resin.

10. The resin sheet according to claim 1, wherein the polyvinyl acetal resin is an α-olefin-modified polyvinyl acetal resin.

11. A resin sheet according to any one of claims 1 to 10, which is a melt-mixed extruded resin sheet.

12. A method for producing a resin sheet, comprising: melting and kneading a resin containing polyvinyl acetal resin having a storage modulus E'(140) of 0.4 to 7.0 MPa at 140°C; melting and extruding the molten mixture into a sheet; and solidifying the sheet-like molten mixture on a casting drum.

13. The method for producing a resin sheet according to claim 12, wherein the melting and kneading temperature is 140 to 180°C.

14. The method for producing a resin sheet according to claim 12, wherein the specific energy of the melt kneading is 0.05 kWh / kg or more.

15. The method for manufacturing a resin sheet according to claim 12, wherein the temperature of the casting drum is 20 to 90°C.

16. The method for producing a resin sheet according to claim 12, wherein the resin that is melt-kneaded includes recovered raw materials.

17. The method for producing a resin sheet according to claim 12, wherein the resin that is melt-kneaded contains a compound having a structure in which a hydrocarbon group having 6 or more carbon atoms is bonded to a polyoxyalkylene group.

18. A laminated glass interlayer comprising a resin sheet according to any one of claims 1 to 10.

19. A laminated glass interlayer comprising the resin sheet described in claim 11.

20. Laminated glass having a plurality of glass plates and a laminated glass interlayer according to claim 18 disposed between the plurality of glass plates.

21. Laminated glass having a plurality of glass plates and a laminated glass interlayer according to claim 19 disposed between the plurality of glass plates.

22. Laminated glass comprising a plurality of glass plates and a laminated glass interlayer comprising the resin sheet according to claim 5, or the resin sheet according to claim 5 which is a melt-kneaded extruded resin sheet, disposed between the plurality of glass plates, wherein the haze measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000 is 1.5% or less.

23. Laminated glass comprising a plurality of glass plates and a laminated glass interlayer comprising the resin sheet according to claim 6, or the resin sheet according to claim 6 which is a melt-kneaded extruded resin sheet, disposed between the plurality of glass plates, wherein the haze measured at a measurement temperature of 20°C and under conditions compliant with JIS K7136:2000 is 5.0% or less.

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