Polyvinyl acetal resin, interlayer film for laminated glass containing the same, and method for manufacturing the same.

Abstract

The objective is to provide a polyvinyl acetal resin, an interlayer film for laminated glass containing the same, and a method for manufacturing the same. [Solution] The present invention relates to a specific surface area of ​​0.1000 to 1.4000 m² measured by the BET method. 2 / g, apparent specific gravity of 0.200~0.350 g / cm³ 3 The present invention provides a polyvinyl acetal resin having a D50 particle size of 75.0 to 187.5 μm. The polyvinyl acetal resin of the present invention can be used in various applications such as interlayers for laminated glass, paints, or adhesives. Products made from the polyvinyl acetal resin of the present invention have excellent optical properties such as low yellowness, high transmittance, and high brightness. Furthermore, products made after leaving the polyvinyl acetal resin at room temperature for 48 hours maintain the aforementioned good optical properties and exhibit excellent stability and durability.

Description

[Technical Field]

[0001] The present invention relates to polyvinyl acetal products, and more particularly to polyvinyl acetal resin, interlayer films for laminated glass containing the same, and methods for producing the same, but the present invention is not limited to these. [Background technology]

[0002] Polyvinyl acetal resin exhibits excellent adhesion and compatibility with various inorganic and organic substrates, excellent solubility in organic solvents, and superior optical properties. Therefore, it is widely used in various adhesives, ceramic adhesives, various inks and paints, and as an interlayer for laminated glass in automobiles and buildings.

[0003] Polyvinyl acetal resin is a resin composition obtained by condensing polyvinyl alcohol and an aldehyde. The manufacturing method generally includes the steps of preparing an aqueous solution of polyvinyl alcohol, carrying out an acetalization reaction, washing with water to remove impurities, and performing a drying procedure to remove excess moisture.

[0004] In recent years, the industry has seen increasing demands for the durability and optical properties of polyvinyl acetal resins. For example, in order to obtain interlayers for laminated glass with excellent properties, products made from polyvinyl acetal resin must have low yellowness, high brightness, and high transmittance. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Conventional polyvinyl acetal resins often suffer from problems such as excessively low transmittance and brightness, and high yellowness. In this regard, the inventors have found that pores exist between polyvinyl acetal resin particles and when particles aggregate. During the washing and drying process in the manufacturing process, if the pores are too small, impurities and residual acids are not easily washed away with water and tend to get mixed into the pores of the polyvinyl acetal resin, causing the polyvinyl acetal resin to yellow during the subsequent drying process. If the pores are too large, the resin easily absorbs moisture when left after the drying process, causing hydrolysis and yellowing of the polyvinyl acetal resin. Referring to Figure 1, the term "pore" as used herein refers to "mesopore A" formed between polyvinyl acetal resin particles P when they aggregate to form aggregates, and "macropore B" formed between aggregates.

[0006] Referring further to Figure 1, in addition to the mesopores and macropores defined above, the term "pore" as used herein also includes "micropores C," which are pores present on the surface of polyvinyl acetal resin particles that have surface roughness. Micropores may adsorb impurities remaining after the reaction, and may also adsorb airborne particles when the finished product is left standing. If too many impurities are adsorbed, the optical properties of the polyvinyl acetal resin may deteriorate (e.g., transmittance is too low, brightness is too low). [Means for solving the problem]

[0007] To solve the above problems, one aspect of the present invention relates to a specific surface area measured by the BET method (hereinafter referred to as BET specific surface area) of 0.1000 to 1.4000 m². 2 / g, apparent specific gravity of 0.200~0.350 g / cm³ 3 The present invention provides a polyvinyl acetal resin with a D50 particle size of 75.0 to 187.5 μm.

[0008] According to some embodiments of the present invention, the polyvinyl acetal resin is a polyvinyl acetoacetal resin, a polyvinyl butyral resin, or a vinyl acetal polymer = acetal = butyral.

[0009] According to some preferred embodiments of the present invention, the specific surface area of the polyvinyl acetal resin measured by the BET method is 0.1000 to 0.5000 m 2 / g.

[0010] According to some preferred embodiments of the present invention, the apparent specific gravity of the polyvinyl acetal resin is 0.217 to 0.314 g / cm 3 3.

[0011] According to some preferred embodiments of the present invention, the D50 particle size of the polyvinyl acetal resin is 100.0 to 187.5 μm.

[0012] According to some embodiments of the present invention, the degree of acetalization of the polyvinyl acetal resin is 75.0 to 85.0% by weight.

[0013] According to some embodiments of the present invention, the hydroxyl group content of the polyvinyl acetal resin is 15.0 to 25.0% by weight.

[0014] According to some embodiments of the present invention, the number average molecular weight of the polyvinyl acetal resin is 15,000 to 160,000.

[0015] According to some embodiments of the present invention, the moisture content of the polyvinyl acetal resin is less than 0.10% by weight.

[0016] Another aspect of the present invention provides a laminate including a first glass plate, a second glass plate disposed opposite to the first glass plate, and an intermediate film disposed between the first glass plate and the second glass plate and made of the aforementioned polyvinyl acetal resin.

[0017] According to some embodiments of the present invention, the yellowness of the laminate is less than 3.0.

[0018] According to some embodiments of the present invention, the transmittance of the laminate is greater than 87.5%.

[0019] According to some embodiments of the present invention, the lightness L* value of the laminate is greater than 90.0, and the chromaticity b* value is greater than 0 and less than 3.0.

[0020] According to some embodiments of the present invention, when the intermediate film is left standing for 48 hours in an environment of a temperature of 23°C and a relative humidity of 25% before being disposed between the first glass plate and the second glass plate, the yellowness of the laminate is less than 3.0.

[0021] According to some embodiments of the present invention, when the intermediate film is left standing for 48 hours in an environment of a temperature of 23°C and a relative humidity of 25% before being disposed between the first glass plate and the second glass plate, the transmittance of the laminate is greater than 87.5%.

[0022] According to some embodiments of the present invention, when the intermediate film is left standing for 48 hours in an environment of a temperature of 23°C and a relative humidity of 25% before being disposed between the first glass plate and the second glass plate, the lightness L* value of the laminate is greater than 90.0, and the chromaticity b* value is greater than 0 and less than 3.0.

[0023] Another aspect of the present invention provides a method for producing the polyvinyl acetal resin described above, comprising the following steps (A) to (D): (A) Preparation of an aqueous polyvinyl alcohol solution: An acid catalyst and a nonionic surfactant are added to an aqueous polyvinyl alcohol solution having a solid content of 8 to 14% by weight, and dissolved at the dissolution temperature, the concentration of the nonionic surfactant being 0.05 to 4.00% by weight; (B) Acetalization reaction: An aldehyde is added to the aqueous polyvinyl alcohol solution, and an acetalization reaction is carried out at a reaction temperature of 15 to 80°C; (C) Washing with water: Sodium hydroxide is added to a pH of 10 to stop the reaction, and then washed with water to remove impurities and residual acid; (D) Drying: The resin is dried at a drying temperature to obtain the polyvinyl acetal resin.

[0024] According to some embodiments of the present invention, in step (A), the dissolution temperature is 85 to 95°C.

[0025] According to some embodiments of the present invention, in step (B), the aldehyde is acetaldehyde, butyraldehyde, or a mixture thereof.

[0026] According to some embodiments of the present invention, in step (D), the drying temperature is 60 to 70°C.

[0027] According to some embodiments of the present invention, in step (D), the water content of the polyvinyl acetal resin is less than 0.1% by weight.

[0028] Another aspect of the present invention provides an interlayer film for laminated glass containing the aforementioned polyvinyl acetal resin. [Effects of the Invention]

[0029] The polyvinyl acetal resin of the present invention can be used in a variety of applications, such as interlayers for laminated glass, paints, or adhesives. Products made from the polyvinyl acetal resin obtained from the technical details of the present invention possess excellent optical properties such as low yellowness, high transmittance, and high brightness. Furthermore, products made after leaving the polyvinyl acetal resin at room temperature for 48 hours maintain the aforementioned good optical properties and exhibit excellent stability and durability.

[0030] To better understand the above-mentioned and other objectives, features, advantages, and embodiments of the present invention, they will be described below with reference to the drawings. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram showing micropores, mesopores, and macropores related to one embodiment of the present invention. [Modes for carrying out the invention]

[0032] To provide a more detailed and complete description of the present invention, the following is provided as an illustrative description of embodiments and specific examples of the present invention, but this is not the only way to carry out or operate specific examples of the present invention. In this specification and the appended claims, unless the context indicates otherwise, "one" and "the" may also be interpreted as plural.

[0033] In this specification and the attached claims, unless otherwise specified, "distributed on something" can be interpreted as directly or indirectly contacting the surface of an object through adhesion or other means, and the identification of such surface shall be determined based on the meaning of the surrounding context / paragraphs of the specification and common sense of the art to which this specification belongs.

[0034] The numerical ranges and parameters defining this invention are approximate, but the relevant numerical values ​​in the specific examples are presented here as accurately as possible. However, any numerical value inevitably includes the standard deviation of the individual test method. The term "approximately" as used herein indicates that the actual value is within the acceptable standard error of the mean and is determined by the opinion of a person of ordinary skill in the art to which this invention pertains.

[0035] [Polyvinyl acetal resin] One aspect of the present invention relates to a material whose specific surface area measured by the BET method (hereinafter referred to as the BET specific surface area) is 0.1000 to 1.4000 m². 2 / g, apparent specific gravity of 0.200~0.350 g / cm³ 3 The present invention provides a polyvinyl acetal resin with a D50 particle size of 75.0 to 187.5 μm.

[0036] As used herein, "polyvinyl acetal resin" means a resin obtained by a condensation reaction between polyvinyl alcohol and an aldehyde. The polyvinyl alcohol is a polymer obtained by saponifying a vinyl ester polymer obtained by polymerizing vinyl ester monomers, and the degree of saponification of polyvinyl alcohol is usually 70.0 to 99.9 mol%, specifically a value within the range of any two of the following values, for example, 70.0 mol%, 75.0 mol%, 80.0 mol%, 85.0 mol%, 90.0 mol%, 95.0 mol%, 99.0 mol%, or 99.9 mol%.

[0037] Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl octanoate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl trimethylacetate, vinyl 2,2,4,4-tetramethylpentanoate, and vinyl tert-valerate. However, the present invention is not limited to these, although vinyl acetate is preferred. The vinyl ester polymer is preferably a polymer obtained using one or more vinyl ester monomers as monomers, and more preferably a polymer obtained using one vinyl ester monomer as monomers. The vinyl ester polymer may also be a copolymer of one or more vinyl ester monomers and other copolymerizable monomers.

[0038] Examples of copolymerizable monomers include olefins having 3 to 30 carbon atoms such as ethylene, propylene, 1-butene, and isobutylene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate Methacrylic acid esters such as propyl, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid or its salts, acrylamidepropyldimethylamine or its salts, N-methylolacrylamide and its Examples include acrylamide derivatives such as derivatives; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salts, methacrylamidepropyldimethylamine or its salts, N-methylolmethacrylamide or its derivatives; N-vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; vinyl ethers such as 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 ether, dodecyl vinyl ether, and stearyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or its salts, its esters, or its anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate. Furthermore, the vinyl ester polymer may have one or more structural units derived from these copolymerizable monomers.

[0039] The aldehyde can generally be an aldehyde having 1 to 10 carbon atoms, such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-hexanal, n-octylaldehyde, n-nonanal, benzaldehyde, or a combination thereof. Aldehydes, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, n-valeraldehyde, or a combination thereof are preferred, and aldehydes, n-butyraldehyde, isobutyraldehyde, or a combination thereof are more preferred. According to a preferred embodiment of the present invention, the polyvinyl acetal resin is a resin obtained by condensing polyvinyl acetal resin, polyvinyl butyral resin, or polyvinyl alcohol with acetaldehyde and butyraldehyde.

[0040] As used herein, "D50 particle diameter" refers to the particle diameter corresponding to a cumulative frequency of 50% (D50) in the particle diameter distribution. The physical meaning of D50 is that 50% of the particles have a diameter greater than this value, and 50% of the particles have a diameter smaller than this value. According to some embodiments of the present invention, the D50 particle diameter of the polyvinyl acetal resin is 75.0 to 187.5 μm, specifically, a value within the range of any two of the following values, for example, 75.0 μm, 100.0 μm, 125.0 μm, 150.0 μm, 175.0 μm, or 187.5 μm, and preferably 100.0 to 187.5 μm. Without being bound by any particular theory, the inventors have found that the size of the mesopores formed in the polyvinyl acetal resin is related to the D50 particle diameter, and that yellowing occurs in the polyvinyl acetal resin if the D50 particle diameter is too large or too small. In other words, by controlling the D50 particle diameter of the polyvinyl acetal resin, it is possible to partially avoid the occurrence of yellowing, which helps to achieve the effects of the present invention.

[0041] As used in this specification, the "apparent specific gravity" refers to the numerical value of the apparent specific gravity measured according to the test method described in JIS K 6720-2:1999 standard. According to some embodiments of the present invention, the apparent specific gravity of the polyvinyl acetal resin is 0.200 to 0.350 g / cm 3 and specifically, it is a value below or within the range between any two of the following values, for example, 0.200 g / cm 3 , 0.220 g / cm 3 , 0.240 g / cm 3 , 0.260 g / cm 3 , 0.280 g / cm 3 , 0.300 g / cm 3 , 0.320 g / cm 3 , 0.340 g / cm 3 or 0.350 g / cm 3 and preferably it is 0.217 to 0.314 g / cm 3 . Without being bound by a specific theory, the inventors of the present invention found that the size of the macropores formed by the polyvinyl acetal resin is related to the apparent specific gravity, and if the numerical value of the apparent specific gravity is too large or too small, yellowing occurs in the polyvinyl acetal resin. In other words, by controlling the numerical value of the apparent specific gravity of the polyvinyl acetal resin, the occurrence of yellowing can be partially avoided, which is helpful for achieving the effects of this application.

[0042] As used in this specification, the "BET specific surface area" refers to the numerical value of the specific surface area measured according to the method described in ISO 15901-2:2022 "Method for measuring the specific surface area of powders (solids) by gas adsorption", for example, the nitrogen gas adsorption method. According to some embodiments of the present invention, the BET specific surface area of the polyvinyl acetal resin is 0.1000 to 1.4000 m 2 / g, and specifically, it is a value below or within the range between any two of the following values, for example, 0.1000 m 2 / g, 0.2000 m 2 / g, 0.3000 m 2 / g, 0.4000 m 2 / g, 0.5000 m 2 / g, 0.6000 m 2 / g, 0.7000 m2 / g, 0.8000m 2 / g, 0.9000m 2 / g, 1.0000m 2 / g, 1.1000m 2 / g, 1.2000m 2 / g, 1,3000m 2 / g or 1,4000m 2 The value is / g, preferably 0.1000~0.8000m 2 / g, more preferably 0.1000~0.5000m 2 The value is / g. Although not bound by any particular theory, the ability of the micropores of the polyvinyl acetal resin to adsorb impurities and suspended particles is related to the size of the BET specific surface area. If the BET specific surface area is too large or too small, the optical properties and durability (stability) of the polyvinyl acetal resin will decrease. In other words, by controlling the BET specific surface area value of the polyvinyl acetal resin, it is possible to partially avoid the decrease in optical properties and stability / durability, which helps to achieve the effects of the present invention.

[0043] In this specification, the "degree of acetalization" of polyvinyl acetal resin is a value expressed as a weight percentage obtained by dividing the amount of ethylene groups to which acetal groups are bonded by the total amount of ethylene groups in the main chain, and is measured according to the test method described in JIS K6728:1977. According to some embodiments of the present invention, the degree of acetalization of the polyvinyl acetal resin is 75.0 to 85.0% by weight, specifically a value within the range of any two of the following values, for example, 75.0% by weight, 77.0% by weight, 79.0% by weight, 81.0% by weight, 83.0% by weight, or 85.0% by weight, and preferably 78.3 to 80.8% by weight.

[0044] In this specification, the "hydroxyl group content" of the polyvinyl acetal resin refers to the weight percentage obtained by dividing the amount of ethylene groups to which hydroxyl groups are bonded by the total amount of ethylene groups in the main chain, and is measured according to the test method described in JIS K6728:1977. According to some embodiments of the present invention, the hydroxyl group content of the polyvinyl acetal resin is 15.0 to 25.0% by weight, specifically, the values ​​listed below or within the range of any two of these values, for example, 15.0% by weight, 16.0% by weight, 17.0% by weight, 18.0% by weight, 19.0% by weight, 20.0% by weight, 21.0% by weight, 22.0% by weight, 23.0% by weight, 24.0% by weight, or 25.0% by weight, and is preferably 18.2 to 20.7% by weight.

[0045] In this specification, the "degree of acetylation" of the polyvinyl acetal resin is a value expressed as a weight percentage obtained by dividing the value obtained by subtracting the amount of ethylene groups to which acetal groups are attached and the amount of ethylene groups to which hydroxyl groups are attached from the total amount of ethylene groups in the main chain by the total amount of ethylene groups in the main chain, and is measured according to the test method described in JIS K6728:1977. In some embodiments of the present invention, the degree of acetylation of the polyvinyl acetal resin is 0.1 to 5.0% by weight, for example, 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5.0%, and is preferably 0.5 to 2.0% by weight.

[0046] As used herein, "number-average molecular weight" refers to the statistical average value of the molecular weights of all polymer chains in a polyvinyl acetal resin and is used to characterize the molecular weight distribution. According to some embodiments of the present invention, the number-average molecular weight of the polyvinyl acetal resin is 15,000 to 160,000, specifically, within the range of the following values ​​or any two of these values, for example, 15,000, 25,000, 35,000, 45,000, 55,000, 65,000, 75,000, 85,000, 95,000, 105,000, 115,000, 125,000, 135,000, 145,000, 155,000, or 160,000, preferably 17,656 to 150,254.

[0047] The polyvinyl acetal resins used herein generally have a water content within a specific range. According to some embodiments of the present invention, the water content of the polyvinyl acetal resin is less than 0.10% by weight, specifically, for example, less than 0.10% by weight, less than 0.08% by weight, less than 0.06% by weight, less than 0.04% by weight, or less than 0.02% by weight.

[0048] Furthermore, in cases where no adverse effects occur, the aforementioned polyvinyl acetal resin may further contain softeners, stabilizers, antioxidants, heat stabilizers, anti-aging agents, UV shielding agents, UV absorbers, flame retardants, lubricants, flow aids, crosslinking agents, colorants, dyes, pigments, fillers, preservatives, antifungal agents, antistatic agents, coupling agents, chelating agents, dispersants, adhesion modifiers, moisture resistance improvers, fluorescent whitening agents, infrared absorbers, infrared shielding agents, or combinations thereof.

[0049] Examples of the softening agent, also called a plasticizer, include monobasic acid esters, polybasic acid esters, organic phosphoric acid, organic phosphorous acid, or combinations thereof. Specifically, examples include triethylene glycol bis(2-ethylhexanoate), 3GO, tetraethylene glycol bis(2-ethylhexanoate), triethylene glycol-bis-(2-ethylbutanoate), tetraethylene glycol-bis-(2-ethylbutanoate), triethylene glycol-di-heptanoate, tetraethylene glycol-di-heptanoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, hexylcyclohexyl adipate, diisononyl adipate, and Bis[2-(2-butoxyethoxy)ethyl] dipic acid, polyadipic acid ester, propylene glycol dibenzoate, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diisononyl phthalate, dibutoxyethyl terephthalate, castor oil, methyl castor oil ester, soybean oil, epoxidized soybean oil, or a combination thereof.

[0050] Examples of the aforementioned antioxidants include phenolic antioxidants, sulfuric antioxidants, and phosphorusic antioxidants. The phenolic antioxidants are antioxidants having a phenol skeleton, and specifically include, for example, 2,6-di-tert-butylp-cresol (BHT), butylated hydroxyanisole (BHA), 2,6-di-tert-butyl-4-ethylphenol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)stearylpropionate, 2,2′-methylenebis(4-methyl-6-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis(3-methyl-6-tert-butylphenol), and 1,1,3-tris(2-methylphenyl) These include droxy-5-tert-butylphenyl)butane, tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane, 1,3,3-tris(2-methyl-4-hydroxy-5-tert-butylphenol)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, bis(3,3′-tert-butylphenol)butyric acid glycol ester, bis(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid)ethylenebis(oxyethylene), or combinations thereof. The phosphorus-based antioxidants are antioxidants containing a phosphorus atom, and specifically include, for example, tridecyl phosphite, tris(tridecyl) phosphite, triphenyl phosphite, tris(nonylphenyl) phosphite, bis(tridecyl)pentaerythritol diphosphite, bis(decyl)pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, 2,2′-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, and 4,4′-butylidenebis(3-methyl-6-t-butylphenyl ditridecyl phosphite).

[0051] [Method for producing polyvinyl acetal resin] Another aspect of the present invention provides a method for producing the polyvinyl acetal resin described above, comprising the following steps (A) to (D): (A) Preparation of an aqueous polyvinyl alcohol solution: An acid catalyst and a nonionic surfactant are added to an aqueous polyvinyl alcohol solution having a solid content of 8 to 14% by weight, and dissolved at the dissolution temperature, the concentration of the nonionic surfactant being 0.05 to 4.00% by weight; (B) Acetalization reaction: An aldehyde is added to the aqueous polyvinyl alcohol solution, and an acetalization reaction is carried out at a reaction temperature of 15 to 80°C; (C) Washing with water: Sodium hydroxide is added to a pH of 10 to stop the reaction, and then washed with water to remove impurities and residual acid; (D) Drying: The resin is dried at a drying temperature to obtain the polyvinyl acetal resin.

[0052] In step (A), the polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is obtained by saponifying a vinyl ester polymer obtained by polymerizing vinyl ester monomers, and the degree of saponification of the vinyl ester monomer, vinyl ester polymer, and polyvinyl alcohol is as defined above.

[0053] According to some embodiments of the present invention, in step (A), the solid content of the aqueous polyvinyl alcohol solution is 8 to 14% by weight, specifically, within the range of the following values ​​or any two of these values, for example, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, or 14% by weight. Without being bound by any particular theory, the inventors have found that the apparent specific gravity of the polyvinyl acetal resin is related to the solid content of the aqueous polyvinyl alcohol solution. If the solid content concentration of the aqueous polyvinyl alcohol solution is too high, the apparent specific gravity of the polyvinyl acetal resin may become too high, and conversely, if the solid content concentration of the aqueous polyvinyl alcohol solution is too low, the apparent specific gravity of the polyvinyl acetal resin may become too low.

[0054] In step (A), the acid catalyst may be, for example, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, or sulfonic acid, preferably hydrochloric acid, nitric acid, or sulfuric acid, but more preferably hydrochloric acid, and both its concentration and amount used are not limited by the present invention.

[0055] According to some embodiments of the present invention, in step (A), the concentration of the nonionic surfactant is 0.05 to 4.00% by weight, specifically, within the range of the following values ​​or any two of these values, for example, 0.05% by weight, 0.50% by weight, 1.00% by weight, 1.50% by weight, 2.00% by weight, 2.50% by weight, 3.00% by weight, 3.50% by weight, or 4.00% by weight. Without being bound by any particular theory, the inventors have found that the size of the D50 particle diameter of the polyvinyl acetal resin is affected by the concentration of the nonionic surfactant. If the concentration of the nonionic surfactant is too high, the polyvinyl acetal resin becomes more prone to suspension, and the D50 particle diameter of the polyvinyl acetal resin becomes too small. Conversely, if the concentration of the nonionic surfactant is too low, the polyvinyl acetal resin becomes more prone to aggregation, and the D50 particle diameter of the polyvinyl acetal resin becomes too large. Examples of the nonionic surfactants include alkyl ether type surfactants such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether, alkylphenyl ether type surfactants such as polyoxyethylene octylphenyl ether, alkyl ester type surfactants such as polyoxyethylene laurate, alkylamine type surfactants such as polyoxyethylene laurylamine ether, alkylamide type surfactants such as polyoxyethylene laurate, polypropylene glycol ether type surfactants such as polyoxyethylene polyoxypropylene ether, alkanolamide type surfactants such as lauric acid diethanolamide and oleic acid diethanolamide, or allylphenyl ether type surfactants such as polyoxyalkylene allylphenyl ether.

[0056] According to some embodiments of the present invention, in step (A), the melting temperature is 85 to 95°C, specifically a value within the range of any two of the following values, for example, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C.

[0057] According to one embodiment of the present invention, in step (B), the aldehyde is an aldehyde having 1 to 10 carbon atoms, such as formaldehyde, aldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-hexanal, n-octylaldehyde, n-nonanal, benzaldehyde, or a combination thereof, preferably aldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, n-valeraldehyde, or a combination thereof, more preferably aldehyde, n-butyraldehyde, isobutyraldehyde, or a combination thereof.

[0058] According to some embodiments of the present invention, in step (B), the reaction temperature of the acetalization reaction is 15 to 80°C, specifically, within the range of the following values ​​or any two of these values, for example, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C. Without being bound by any particular theory, the inventors have found that the size of the BET specific surface area of ​​the polyvinyl acetal resin is related to the reaction temperature of the acetalization reaction. If the reaction temperature of the acetalization reaction is too high, the reaction becomes too vigorous, resulting in a rough surface of the polyvinyl acetal resin produced and an excessively large BET specific surface area. Conversely, if the reaction temperature of the acetalization reaction is too low, the BET specific surface area becomes too small.

[0059] The drying apparatus used in step (D) is not limited by the present invention. According to some embodiments of the present invention, the drying temperature is 60 to 70°C, specifically a value within the range of any two of the following values, for example, 60°C, 62°C, 64°C, 66°C, 68°C, or 70°C. According to a preferred embodiment of the present invention, the water content of the polyvinyl acetal resin obtained in step (D) is less than 0.10% by weight. Without being bound by any particular theory, the inventors have found that if the water content is too high, the polyvinyl acetal resin becomes prone to adhesion and has a significant effect on the apparent specific gravity and D50 particle size.

[0060] [Laminate and method for manufacturing the same] Another aspect of the present invention provides a laminate comprising a first glass plate, a second glass plate disposed opposite to the first glass plate, and an interlayer made of the aforementioned polyvinyl acetal resin disposed between the first glass plate and the second glass plate.

[0061] The terms "first glass plate" and "second glass plate" are not limited in this invention. According to some embodiments of this invention, one or both of the first glass plate and the second glass plate may be inorganic glass plates such as float glass, air-cooled tempered glass, chemically strengthened glass, and double-glazed glass, or they may be transparent resin substrates, specifically, acrylic resin substrates, polycarbonate substrates, cyclic olefin polymer substrates, and polyester substrates.

[0062] According to some embodiments of the present invention, the yellowness of the laminate is less than 3.0, specifically for example, less than 3.0, less than 2.5, less than 2.0, less than 1.5, less than 1.0, or less than 0.5. According to another embodiment of the present invention, the transmittance of the laminate is greater than 87.5%, specifically for example, greater than 87.5%, greater than 88.0%, greater than 89.0%, greater than 90.0%, greater than 91.0%, greater than 92.0%, greater than 93.0%, greater than 94.0%, greater than 95.0%, greater than 96.0%, greater than 97.0%, greater than 98.0%, or greater than 99%. According to another embodiment of the present invention, the lightness L* value of the laminate is greater than 90.0, specifically for example, greater than 90.0, greater than 91.0, greater than 92.0, greater than 93.0, greater than 94.0, greater than 95.0, or greater than 96.0. The chromaticity b* value of the laminate is greater than 0 and less than 3.0, specifically for example, greater than 0 and less than 3.0, greater than 1 and less than 3.0, greater than 2 and less than 3.0, greater than 0 and less than 2.0, or greater than 1 and less than 2.0. According to a preferred embodiment of the present invention, the yellowness of the laminate is less than 3.0, the transmittance is greater than 87.5%, the lightness L* value is greater than 90.0, and the chromaticity b* value is greater than 0 and less than 3.0.

[0063] According to some preferred embodiments of the present invention, when the interlayer is left for 48 hours in an environment of 23°C and 25% relative humidity before being placed between the first glass plate and the second glass plate, the yellowness of the laminate is still less than 3.0. According to some other preferred embodiments of the present invention, when the interlayer is left for 48 hours in an environment of 23°C and 25% relative humidity before being placed between the first glass plate and the second glass plate, the transmittance of the laminate is still greater than 87.5%. According to some yet another preferred embodiment of the present invention, when the interlayer is left for 48 hours in an environment of 23°C and 25% relative humidity before being placed between the first glass plate and the second glass plate, the lightness L* value of the laminate is still greater than 90.0, and the chromaticity b* value is greater than 0 and less than 3.0. In a particularly preferred embodiment of the present invention, when the interlayer is left for 48 hours in an environment of 23°C and 25% relative humidity before being placed between the first glass plate and the second glass plate, the yellowness of the laminate is still less than 3.0, the transmittance is still greater than 87.5%, the lightness L* value is still greater than 90.0, and the chromaticity b* value is still greater than 0 and less than 3.0.

[0064] In the present invention, the method for manufacturing the laminate is not particularly limited, but it is preferable to include a step of sandwiching an interlayer between a first glass plate and a second glass plate and hot pressing it with a hot press machine.

[0065] [Interlayer for laminated glass] Another aspect of the present invention provides an interlayer for laminated glass containing the polyvinyl acetal resin described above. According to some embodiments of the present invention, the interlayer for laminated glass may have a single-layer structure, preferably with a thickness of 0.2 to 2.0 mm, and more preferably with a thickness of 0.38 to 1.52 mm. According to another embodiment of the present invention, the interlayer for laminated glass may have a two-layer structure including a first layer and a second layer bonded to the upper or lower surface of the first layer, wherein the thickness of the first layer is preferably 0.11 to 0.15 mm, more preferably 0.13 mm, and the thickness of the second layer is preferably 0.32 to 0.35 mm. According to some preferred embodiments of the present invention, the interlayer for laminated glass may have a structure in which the interlayer is sandwiched between upper and lower protective layers. In addition to the three-layer structure, those skilled in the art may add a fourth, fifth, or sixth layer, etc., as needed, and similarly, it is preferable that the interlayer and protective layers are alternately laminated. Specifically, the thickness of the intermediate layer is preferably 0.11 to 0.15 mm, and more preferably 0.13 mm. The thickness of the protective layer is preferably 0.32 to 0.35 mm, and more preferably 0.335 mm. The thickness of the interlayer for laminated glass is preferably 0.5 to 2 mm, and more preferably 0.75 to 0.85 mm, for example, 0.75, 0.76, 0.77, 0.78, 0.80, 0.82, or 0.85 mm. The method for manufacturing the interlayer for laminated glass is not particularly limited in this invention. [Examples]

[0066] The present invention will be described in detail below with reference to specific examples. However, it should be understood that these specific examples are intended to aid in understanding the present invention and are not intended to limit the scope of the invention in any way.

[0067] 1. Preparation of polyvinyl acetal resin Herein, the present invention provides a non-limiting method for preparing polyvinyl acetal resin. Non-limiting examples of polyvinyl acetal resin (Examples 1-8) and comparative examples of polyvinyl acetal resin (Comparative Examples 1-6) were prepared by a method similar to that disclosed below.

[0068] The following are the main steps common to the production of polyvinyl acetal resin in this example and the comparative example. Table 1 below shows in detail the differences in one or more process parameters between this example and the comparative example. 1. Preparation of polyvinyl alcohol aqueous solution: Add approximately 0.1-0.2% by weight of hydrochloric acid with a concentration of 38.5% by volume and polyoxyethylene lauryl ether with a predetermined concentration to a polyvinyl alcohol aqueous solution having a predetermined solid content, and dissolve in the polyvinyl alcohol aqueous solution at a dissolution temperature of 85-95°C. 2. Acetalization reaction step: A predetermined aldehyde (specifically, an aldehyde, butyraldehyde, or a mixture of an aldehyde and butyraldehyde, in a volume ratio of 3:1) is added to the aqueous polyvinyl alcohol solution, and the acetalization reaction is carried out at a predetermined reaction temperature. 3. Washing process: Add a 50 vol% sodium hydroxide aqueous solution to the reaction solution until the pH reaches 10 to stop the reaction, wash with 60°C water for 1.5 hours, and then wash three times with 25°C water for 0.5 hours each to remove impurities and residual acid. 4. Drying process: Dry at a drying temperature of 65°C to obtain polyvinyl acetal resin with a moisture content of less than 0.10% by weight.

[0069] [Table 1]

[0070] [Table 2]

[0071] 2.Analysis method Herein, the present invention provides methods for analyzing and testing polyvinyl acetal resins of Examples 1 to 8 and Comparative Examples 1 to 6 described above.

[0072] Moisture content The water content of the polyvinyl acetal resins in Examples 1-8 and Comparative Examples 1-6 was measured using the constant temperature oven method.

[0073] Test method: 2 g (initial weight) of polyvinyl acetal resin is accurately weighed onto an aluminum foil dish, dried in an oven at 105°C ± 2°C for 2 hours, removed and placed in a desiccator for 10 minutes, the remaining weight is accurately weighed again, and the moisture content is calculated using the following formula.

[0074]

number

[0075] Hydroxyl group content The hydroxyl group content of this invention is measured according to the test method described in JIS K6728:1977.

[0076] Degree of acetylation The degree of acetylation in this invention is measured according to the test method described in JIS K6728:1977.

[0077] Acetalization degree The degree of acetalization in this invention is measured according to the test method described in JIS K6728:1977.

[0078] number average molecular weight The molecular weight distribution of polyvinyl acetal resin is measured by gel permeation chromatography (GPC). The polyvinyl acetal resin is dissolved in tetrahydrofuran (THF), and GPC analysis is performed under the following conditions. The number-average molecular weight (Mn) is calculated as the area ratio of the corresponding polystyrene standard (Waters PS STD).

[0079] Equipment: Waters 1515 PUMP system Detector: Waters 2414 RI Elution conditions: 1.0 ml / min (mL / min), THF Column:Waters Styragel HR5 THF, Waters Styragel HR4 THF, Waters, Styragel HR3 THF, Waters Styragel HR1 THF

[0080] BET specific surface area The BET specific surface area of ​​the present invention is measured according to the test method described in ISO 15901-2:2022.

[0081] Equipment: Micromeritics ASAP 2060 Specific Surface Area Analyzer

[0082] Sample preparation and testing method: Before testing, the polyvinyl acetal resin is placed in an oven at 50°C for 24 hours to remove moisture, so that the water content of the polyvinyl acetal resin is less than 0.1% by weight. Then, the specific surface area is measured under a nitrogen gas atmosphere using a Micromeritics ASAP 2060 specific surface area analyzer.

[0083] Apparent specific gravity The apparent specific gravity of this invention is measured according to the test method described in JIS K 6720-2:1999.

[0084] Sample preparation: Before testing, the polyvinyl acetal resin is placed in an oven at 50°C for 24 hours to remove moisture, so that the moisture content of the polyvinyl acetal resin is less than 0.10% by weight.

[0085] D50 particle size Sample preparation: Before testing, the polyvinyl acetal resin is placed in an oven at 50°C for 24 hours to remove moisture, so that the moisture content of the polyvinyl acetal resin is less than 0.10% by weight.

[0086] Testing equipment: Sieve conforming to ASTM E11-01 international standard.

[0087] Pre-treatment for testing: Sieves of 60, 80, 100, 150, 200, and 270 mesh were washed with pure water, then dried in an oven at a drying temperature of 105°C. After cooling, the weight of each sieve was measured individually.

[0088] Test method Stack sieves of 1.60, 80, 100, 150, 200, and 270 mesh sizes from top to bottom in that order. 2. Place 100g of precisely weighed polyvinyl acetal resin on the top layer (60-mesh sieve), 3. Test using a vibrating sieve for 20 minutes. 4. Obtain a particle size distribution graph, calculate the proportion of each layer, and then calculate the particle size corresponding to a cumulative frequency of 50% (D50).

[0089] 3. Evaluation Methods and Results Herein, the present invention provides a method for evaluating laminates made from polyvinyl acetal resin in Examples 1 to 8 and Comparative Examples 1 to 6, and results corresponding to the above analysis.

[0090] Sample preparation (1) Place the polyvinyl acetal resin in an oven at 50°C for 24 hours, then sandwich the polyvinyl acetal resin between two pieces of clean, transparent glass, the two pieces of transparent glass being circular with a diameter of 9 cm and a thickness of 3 mm, and then hot press it in a hot press machine at 150°C for 3 minutes. (2) The polyvinyl acetal resin is left in an environment with a temperature of 23°C and a relative humidity of 25% for 48 hours. Then the polyvinyl acetal resin is sandwiched between two pieces of clean, transparent glass, the two pieces of transparent glass being circular with a diameter of 9 cm and a thickness of 3 mm. After that, it is hot-pressed in a hot press machine at a temperature of 150°C for 3 minutes.

[0091] Evaluation of yellowness The evaluation of yellowness in this invention is carried out according to the ASTM D1925 procedure. Since ASTM D1925 was discontinued in 1995, the relevant measurement procedure can be carried out according to ASTM E313.

[0092] Equipment and Instruments: Color meter ZE 2000 colorimeter Test method: A Color meter ZE 2000 colorimeter was used to analyze the yellowness of the two types of laminates by shining the light 3.5 cm inward from the outer edge of each. Evaluation method: If the yellowness value is less than 3, it is considered a pass; if the yellowness value is greater than 3, it is considered a fail.

[0093] Evaluation of lightness L* value and chromaticity b* value Equipment and Instruments: Color meter ZE 2000 colorimeter Test method: A Color meter ZE 2000 colorimeter was used to analyze the chromaticity of the two types of laminates by shining the light 3.5 cm inward from the outer edge of each. Evaluation method: A product is considered acceptable if the lightness L* value is greater than 90.0 and the chromaticity b* value is greater than 0 and less than 3.0. If the evaluation results show that the lightness L* value is 90.0 or less and the chromaticity b* value is 0 or less or 3.0 or greater, the product is considered unacceptable.

[0094] Evaluation of Transmittance The transmittance of the present invention is evaluated according to the test method described in ASTM D1003.

[0095] Equipment and Instruments: Nippon NDH2000 Haze Meter Test method: Transmittance will be measured using a Nippon NDH2000 Haze meter. Evaluation method: If the transmittance is greater than 87.5%, it will be considered a pass; if the transmittance is 87.5% or less, it will be considered a fail.

[0096] Furthermore, Table 2 shows the analysis results of the BET specific surface area, apparent specific gravity, and D50 particle diameter of the polyvinyl acetal resins of Examples 1 to 8 and Comparative Examples 1 to 6, as well as the evaluation results of the yellowness, lightness (L*), chromaticity (b*), and transmittance of the laminates corresponding to the said polyvinyl acetal resins.

[0097] [Table 3]

[0098] [Table 4]

[0099] As can be seen from Table 2, the BET specific surface area of ​​the polyvinyl acetal resins in Examples 1 to 8 is 0.1000 to 1.4000 m² in all cases. 2 The values ​​are in the range of / g, and the apparent specific gravity is all between 0.200 and 0.350 g / cm³. 3 The particles are within the range of 75.0 to 187.5 μm, and the D50 particle size is in the range of 75.0 to 187.5 μm. The optical properties of the laminates containing these polyvinyl acetal resins, such as yellowness, chromaticity, and transmittance, are all excellent (pass). The polyvinyl acetal resin has good stability / durability (i.e., even after the polyvinyl acetal resin has been left standing, the optical properties of the laminate made therefrom are still good).

[0100] Conversely, in Comparative Examples 1 to 6, at least one of the BET specific surface area, apparent specific gravity, or D50 particle diameter of the polyvinyl acetal resins falls outside the above range. Laminates containing these polyvinyl acetal resins cannot simultaneously obtain excellent evaluations of yellowness, chromaticity, and transmittance. Furthermore, after leaving the polyvinyl acetal resins at room temperature for 48 hours, it can be observed that their optical properties are even less ideal, indicating a lack of stability and durability.

[0101] In short, the polyvinyl acetal resin of the present invention can be used in a variety of applications, such as interlayers for laminated glass, paints, or adhesives. Products made from the polyvinyl acetal resin obtained from the technical details of the present invention possess excellent optical properties such as low yellowness, high transmittance, and high brightness. Furthermore, products made after leaving the polyvinyl acetal resin at room temperature for 48 hours maintain the aforementioned good optical properties and exhibit excellent stability and durability.

[0102] All ranges provided herein are intended to include each specific range within a given range, and combinations of subranges between given ranges. Furthermore, any range expressed herein includes the endpoint unless otherwise specified. Thus, the range 1–5 includes, in particular, 1, 2, 3, 4, and 5, and subranges such as 2–5, 3–5, 2–3, 2–4, and 1–4.

[0103] All publications and patent applications cited herein are incorporated herein by reference, and for all purposes, individual publications or patent applications are specifically and individually indicated as being incorporated herein by reference. In the event of any conflict between this Specified and any publication or patent application incorporated herein by reference, this Specified shall prevail. [Explanation of Symbols]

[0104] A Mesoporia B Macropore C Micropore P Polyvinyl acetal resin particles

Claims

1. The specific surface area measured by the BET method (hereinafter referred to as BET specific surface area) is between 0.1000 and 1.4000 m². ２ / g, apparent specific gravity of 0.200-0.350 g / cm³ ３ Polyvinyl acetal resin with a D50 particle size of 75.0 to 187.5 μm.

2. The polyvinyl acetal resin according to claim 1, which is a polyvinyl acetal resin, a polyvinyl butyral resin, or a vinyl acetal polymer = acetal = butyral.

3. The specific surface area measured by the BET method is between 0.1000 and 0.5000 m². ２ The polyvinyl acetal resin according to claim 1, wherein the amount is / g.

4. The apparent specific gravity is 0.217–0.314 g / cm³. ３ The polyvinyl acetal resin according to claim 1.

5. The polyvinyl acetal resin according to claim 1, wherein the D50 particle size is 100.0 to 187.5 μm.

6. The polyvinyl acetal resin according to claim 1, wherein the degree of acetalization is 75.0 to 85.0% by weight.

7. The polyvinyl acetal resin according to claim 1, wherein the hydroxyl group content is 15.0 to 25.0% by weight.

8. The polyvinyl acetal resin according to claim 1, wherein the number average molecular weight is 15,000 to 160,000.

9. The polyvinyl acetal resin according to claim 1, wherein the water content is less than 0.10% by weight.

10. A method for producing polyvinyl acetal resin according to any one of claims 1 to 9, (A) Preparation step of polyvinyl alcohol aqueous solution: An acid catalyst and a nonionic surfactant are added to a polyvinyl alcohol aqueous solution having a solid content of 8 to 14% by weight, and dissolved in the polyvinyl alcohol aqueous solution at the dissolution temperature, the concentration of the nonionic surfactant being 0.05 to 4.00% by weight. (B) Acetalization reaction step: Add an aldehyde to the aqueous polyvinyl alcohol solution and carry out the acetalization reaction at a reaction temperature of 15 to 80°C. (C) Washing process: Add sodium hydroxide to bring the pH down to 10 to stop the reaction, then wash with water to remove impurities and residual acid. (D) Drying process: Dry at a drying temperature to obtain polyvinyl acetal resin. A manufacturing method that includes processes such as those mentioned above.

11. The manufacturing method according to claim 10, wherein in step (A), the melting temperature is 85 to 95°C.

12. The manufacturing method according to claim 10, wherein in step (B), the aldehyde is acetaldehyde, butyraldehyde, or a mixture thereof.

13. The manufacturing method according to claim 10, wherein in step (D), the drying temperature is 60 to 70°C.

14. The manufacturing method according to claim 10, wherein in step (D), the water content of the polyvinyl acetal resin is less than 0.10% by weight.

15. An interlayer for laminated glass comprising the polyvinyl acetal resin according to any one of claims 1 to 9.

Images