WO2025187601A1 - Poudre de résine - Google Patents

Poudre de résine

Info

Publication number
WO2025187601A1
WO2025187601A1 PCT/JP2025/007401 JP2025007401W WO2025187601A1 WO 2025187601 A1 WO2025187601 A1 WO 2025187601A1 JP 2025007401 W JP2025007401 W JP 2025007401W WO 2025187601 A1 WO2025187601 A1 WO 2025187601A1
Authority
WO
WIPO (PCT)
Prior art keywords
resin powder
particles
pva
mol
polymerization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/007401
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English (en)
Japanese (ja)
Other versions
WO2025187601A8 (fr
Inventor
真輔 新居
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kuraray Co Ltd
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Kuraray Co Ltd
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Filing date
Publication date
Application filed by Kuraray Co Ltd filed Critical Kuraray Co Ltd
Publication of WO2025187601A1 publication Critical patent/WO2025187601A1/fr
Publication of WO2025187601A8 publication Critical patent/WO2025187601A8/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F216/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
    • C08F216/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an alcohol radical
    • C08F216/04—Acyclic compounds
    • C08F216/06—Polyvinyl alcohol ; Vinyl alcohol
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/12—Hydrolysis
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating

Definitions

  • the present invention relates to a resin powder.
  • PVA Vinyl alcohol polymer
  • PVAc saponifying polyvinyl ester
  • PVA is typically obtained by radically polymerizing vinyl acetate in a methanol solvent to obtain a methanol solution of vinyl acetate polymer, followed by the addition of an alkaline catalyst for saponification.
  • the PVA composition obtained through saponification, which contains the solvent, is then subjected to drying and other processes to obtain a PVA resin powder (see Patent Document 1, etc.).
  • PVA resin powders containing PVA generally have the disadvantage of poor drying efficiency. In order to shorten the drying process and save energy during the production of resin powders, thereby reducing production costs, it is desirable to improve the drying efficiency of resin powders. Furthermore, PVA resin powder obtained after drying may be re-dried after undergoing treatment with a liquid (for example, the synthesis of modified PVA, a process known as post-modification), or moisture-absorbed PVA resin powder may be re-dried as needed. Even when such re-drying is performed, it is desirable for the PVA resin powder to have high drying efficiency.
  • a liquid for example, the synthesis of modified PVA, a process known as post-modification
  • the resin powder is an aggregate of a plurality of particles (PVA particles), and these plurality of particles (PVA particles) include a plurality of bubble-containing particles.
  • the resin powder may be composed solely of a plurality of these particles (PVA particles).
  • the resin powder according to one embodiment of the present invention has improved drying efficiency compared to conventional resin powders.
  • the reason for this is not entirely clear, but it is speculated that the resin powder contains a sufficient amount of bubble-containing particles, which increases its surface area.
  • the center of the particle is less likely to be heated sufficiently when dried by heating, making it difficult for the volatile components in the center of the particle to volatilize.
  • the presence of bubbles suppresses this phenomenon, which is speculated to be another reason for the improved drying efficiency.
  • the ease of drying resin powders containing PVA is greatly influenced by the physical properties of the PVA itself (degree of saponification, degree of polymerization, presence or absence of modified species and amount of modification, etc.) and the particle size of the resin powder. Therefore, in this specification, “improved drying efficiency” means that the drying time is sufficiently shortened compared to a resin powder of substantially the same particle size that uses the same type of PVA.
  • “Same type of PVA” refers to PVA with the same degree of saponification, degree of polymerization, presence or absence of modified species, and amount of modification.
  • Modified species refers to monomers other than vinyl esters.
  • Amount of modification refers to the content of monomer units derived from these other monomers relative to the total monomer units in the PVA.
  • the resin powder according to one embodiment of the present invention has a low content of organic volatile matter and a high rate of dissolution in water. This is presumably because the resin powder contains a sufficient amount of bubble-containing particles, resulting in a sufficiently increased surface area. Furthermore, because the surface area of the resin powder is sufficiently increased, it is believed that the reactivity of the resin powder when subjected to post-modification, etc., is also good.
  • PVA is a polymer containing vinyl alcohol units as monomer units.
  • PVA is typically obtained by saponifying polyvinyl ester.
  • the lower limit of the vinyl alcohol unit content relative to all monomer units in PVA is preferably 35 mol%, more preferably 50 mol%, even more preferably 70 mol%, and may be 80 mol%, 85 mol%, 90 mol%, or 95 mol%.
  • the vinyl alcohol unit content in PVA increases, drying generally tends to take longer. Therefore, when the present invention is applied to a resin powder containing PVA with a high vinyl alcohol unit content, the advantage of improved drying efficiency is particularly pronounced.
  • the lower limit of the saponification degree of the PVA is preferably 35 mol%, more preferably 50 mol%, even more preferably 70 mol%, and may be 80 mol%, 85 mol%, 90 mol%, or 95 mol%.
  • the saponification degree of the PVA increases, drying generally tends to take longer. Therefore, when the present invention is applied to a resin powder containing a PVA with a high saponification degree, the advantage of improved drying efficiency is particularly pronounced.
  • the upper limit of the saponification degree may be 100 mol%, but is preferably 99.99 mol%, more preferably 99 mol%, or may be 98 mol%, 95 mol%, or 90 mol%.
  • the saponification degree is a value measured by the method described in JIS K6726:1994.
  • PVA may contain other monomer units in addition to vinyl alcohol units and vinyl ester units.
  • Monomers (modified species) that provide the other monomer units include ⁇ -olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene; acrylic acid, methacrylic acid; acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; maleic acid and its derivatives such as maleic acid, monomethyl maleate, and dimethyl maleate; acrylamide derivatives such as N-methylacrylamide and N-ethylacrylamide; methacrylamide derivatives such as N-methylmethacrylamide and N-ethylmethacrylamide; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and n-butyl vinyl ether; ethylene
  • the upper limit of the content (modification amount) of the other monomer units relative to the total monomer units in the PVA may preferably be 20 mol%, and more preferably 10 mol%.
  • the upper limit of the content of the other monomer units may be 5 mol%, 3 mol%, 1 mol%, or 0.1 mol%.
  • the lower limit of the content of the other monomer units may be, for example, 0.1 mol%, or 1 mol%.
  • the viscosity-average degree of polymerization of the PVA is not particularly limited, but its lower limit is preferably 200, more preferably 250, even more preferably 400, and particularly preferably 600, and may be 1,000, 1,500, or 2,000. As the viscosity-average degree of polymerization of the PVA increases, drying generally tends to take longer. Therefore, when the present invention is applied to a resin powder containing a PVA with a high viscosity-average degree of polymerization, the advantage of improving drying efficiency is particularly easily achieved.
  • the upper limit of the viscosity-average degree of polymerization is preferably 5,000, more preferably 4,500, and even more preferably 3,500, and may be 3,000, 2,500, or 2,000.
  • the viscosity-average degree of polymerization of the PVA is equal to or less than the upper limit, drying time can be shortened.
  • the resin powder according to one embodiment of the present invention may contain components other than PVA.
  • Non-volatile components other than PVA that may be contained in the resin powder include resins other than PVA, surfactants, additives such as plasticizers, and various compounds used during production.
  • the upper limit of the volatile content in a resin powder according to one embodiment of the present invention may be, for example, 5.0% by mass or 4.0% by mass, but is preferably 3.0% by mass. Having a volatile content equal to or less than this upper limit can improve handleability, etc.
  • the lower limit of the volatile content may be, for example, 0.1% by mass, or 0.5%, 1.0%, or 1.5% by mass.
  • the organic volatile matter and volatile matter content of a resin powder according to one embodiment of the present invention can be measured in accordance with JIS K6726:1994. For example, if the volatile matter content of a resin powder measured in accordance with the above standard is 3.0% by mass, it is clear that the organic volatile matter content is 3.0% by mass or less.
  • the lower limit of the average particle diameter of the resin powder according to one embodiment of the present invention is 100 ⁇ m, preferably 150 ⁇ m, more preferably 300 ⁇ m, and even more preferably 400 ⁇ m.
  • the average particle diameter is increased, facilitating the production of solutions such as aqueous solutions, preventing scattering and adhesion to walls, and reducing the risk of dust explosions, thereby improving handleability.
  • the average particle diameter of a resin powder increases, it generally tends to take longer to dry. Therefore, when the present invention is applied to resin powders with a relatively large average particle diameter, the advantage of improving drying efficiency is particularly pronounced.
  • the upper limit of the average particle diameter is 2,000 ⁇ m, preferably 1,500 ⁇ m, more preferably 1,000 ⁇ m, and even more preferably 850 ⁇ m. Setting the average particle diameter at or below this upper limit can shorten drying time.
  • the average particle diameter of the resin powder is a value measured in accordance with the method described in JIS K7369:2009.
  • a resin powder according to one embodiment of the present invention contains particles having a particle diameter of 106 to 1,000 ⁇ m.
  • the lower limit of the number of bubble-containing particles (bubble particle count) among 100 particles randomly selected from the particles having a particle diameter of 106 to 1,000 ⁇ m contained in the resin powder is 10, preferably 15, more preferably 20, even more preferably 30, and even more preferably 40, 45, or 50. Having a bubble-containing particle count equal to or greater than the lower limit can improve drying efficiency, etc.
  • the upper limit of the bubble-containing particle count may be 100, or may be 90, 80, 70, or 60.
  • bubble-containing particles can be obtained by introducing a gas into a slurry or solid containing PVA, for example, in the saponification process or a subsequent process.
  • the number of bubble-containing particles can be adjusted by adjusting the amount of gas introduced, etc.
  • the lower limit of the average bubble size in the bubble-containing particles of the resin powder according to one embodiment of the present invention is 1 ⁇ m, preferably 10 ⁇ m, more preferably 30 ⁇ m, even more preferably 40 ⁇ m, and even more preferably 50 ⁇ m.
  • the upper limit of the average bubble size is preferably 200 ⁇ m, more preferably 100 ⁇ m. By setting the average bubble size at or below this upper limit, it is possible to increase the productivity of the resin powder.
  • the average bubble size is the average value of the size of bubbles of 1 ⁇ m or more contained in the bubble-containing particles (bubble size).
  • the average bubble size can be adjusted, for example, by the pore size of a filter used when introducing gas into a slurry or solid containing PVA.
  • the number of bubble-containing particles and average bubble size of resin powder are determined using the following method.
  • 100 particles are randomly extracted from the resin powder particles with a particle diameter of 106 to 1,000 ⁇ m.
  • Particles with a particle diameter of 106 to 1,000 ⁇ m can be selected as particles that pass through a sieve with a nominal opening of 1,000 ⁇ m (16 mesh) but do not pass through a sieve with a nominal opening of 106 ⁇ m (150 mesh).
  • the mechanical sieving can be performed, for example, using the method described in JIS K7369:2009.
  • Each extracted particle is observed using a microscope to determine the presence or absence of bubbles and to measure the bubble size (bubble diameter). Observation and measurement of each particle using a microscope are performed from directly above each particle placed on a horizontal plane.
  • the bubble size is the diameter of the circle; if the bubbles are elliptical, the bubble size is the major axis.
  • the average bubble size is the average value of the bubble sizes of bubbles 1 ⁇ m or larger contained in the observed bubble-containing particles.
  • Bubbles include not only completely closed bubbles (those present inside the particle) but also those that are not completely closed (those with a circular or elliptical recessed surface shape that is thought to be caused by bubbles). Even for bubbles that are not completely closed (those with a circular or elliptical recessed surface shape that is thought to be caused by bubbles), the diameter or major axis is considered to be the bubble size.
  • the gas contained in the bubbles of the bubble-containing particles contains an inert gas. Furthermore, from the standpoint of handleability, etc., it is preferable that the gas contained in the bubbles of the bubble-containing particles is an inorganic substance. From these standpoints and from the standpoint of production costs, the gas contained in the bubbles of the bubble-containing particles is preferably air or nitrogen, and more preferably nitrogen. The nitrogen content in the gas contained in the bubbles of the bubble-containing particles is preferably 78% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more.
  • the content of particles having a particle diameter of 106 to 1,000 ⁇ m is not particularly limited, but the lower limit is preferably 50% by mass, more preferably 60% by mass, and even more preferably 70% by mass. Meanwhile, the upper limit of the content of particles having a particle diameter of 106 to 1,000 ⁇ m may be 100% by mass, 99% by mass, or 95% by mass. By keeping the content of particles having a particle diameter of 106 to 1,000 ⁇ m within the above range, drying efficiency is further improved.
  • the content of particles having a particle diameter of 106 to 1,000 ⁇ m in the resin powder can be determined according to the method described in JIS K7369:2009, using a sieve with a nominal mesh size of 1,000 ⁇ m (16 mesh) and a sieve with a nominal mesh size of 106 ⁇ m (150 mesh).
  • the bulk density is not particularly limited, but the upper limit is preferably 0.7 g/mL, more preferably 0.6 g/mL, and even more preferably 0.55 g/mL.
  • the lower limit of the bulk density is preferably 0.4 g/mL.
  • the bulk density of the resin powder is Resin powder is poured into a 100 mL measuring cylinder up to 100 mL under conditions of 25°C and 50% RH, and the mass is measured from the volume (100 mL) and the mass (unit: g) of the resin powder placed in the measuring cylinder.
  • the upper limit of the product of its average particle size ( ⁇ m) and its bulk density (g/mL) is preferably 700 ⁇ m ⁇ g/mL, more preferably 500 ⁇ m ⁇ g/mL, even more preferably 400 ⁇ m ⁇ g/mL, and even more preferably 350 ⁇ m ⁇ g/mL, 320 ⁇ m ⁇ g/mL, or 300 ⁇ m ⁇ g/mL.
  • the product of the average particle size ( ⁇ m) and bulk density (g/mL) of the resin powder is equal to or less than the upper limit, it means that the bulk density is low relative to the particle size.
  • the lower limit of this product may be, for example, 100 ⁇ m ⁇ g/mL, 150 ⁇ m ⁇ g/mL, or 200 ⁇ m ⁇ g/mL.
  • the resin powder according to one embodiment of the present invention can be used in a variety of applications, examples of which are given below, but are not limited thereto.
  • Vinyl chloride dispersant applications Dispersion stabilizers and dispersion aids for suspension polymerization of vinyl chloride and vinylidene chloride.
  • Coating applications Sizing agents, fiber processing agents, leather finishing agents, paints, anti-fogging agents, metal corrosion inhibitors, zinc plating gloss agents, antistatic agents.
  • Adhesives and binder applications Adhesives, pressure sensitive adhesives, rewet adhesives, various binders, additives for cement and mortar.
  • Dispersion stabilizer applications Dispersion stabilizers for organic and inorganic pigments in paints and adhesives, dispersion stabilizers for emulsion polymerization of various vinyl compounds, post-emulsifiers for bitumen, etc.
  • Paper processing applications Paper strength enhancers, oil and solvent resistance agents, smoothness improvers, surface gloss improvement aids, fillers, barrier agents, light resistance agents, water resistance agents, dye and color developer dispersants, adhesion improvers, binders.
  • Agricultural applications Pesticide binders, pesticide spreaders, agricultural coating agents, soil improvement agents.
  • Medical and cosmetic uses granulation binders, coating agents, emulsifiers, patches, binders, film formulation base materials, film-forming agents (8)
  • Viscosity adjusters thickeners, rheology adjusters (9)
  • Flocculants flocculants for suspended and dissolved substances in water, metal flocculants (10)
  • Molded products fibers, pipes, tubes, leak-proof membranes, water-soluble fibers for chemical lace, sponges (12)
  • Resin raw materials raw materials for polyvinyl butyral, raw materials for photosensitive resins, raw materials for graft polymers, raw materials for various gels (13)
  • the method for producing the resin powder of the present invention is not particularly limited, it is preferable to incorporate gas bubbles into particles during any of the general PVA production processes, such as polymerization, saponification, washing, drying, and pulverization. In this production method, it is preferable to introduce a gas into the system to obtain a solid product containing PVA and having gas bubbles formed therein.
  • the term "in system” may refer to a liquid, gel, or solid mixture containing PVA.
  • the term “in system” may refer to a liquid, gel, or solid mixture containing at least one of the reactants and products used in producing PVA.
  • the term "in system" in the saponification step may refer to the reaction liquid during the saponification reaction.
  • a portion of the reaction liquid in the saponification reaction liquid may be in a gel or solid state.
  • the introduction of gas into the system is preferably carried out during the saponification step. That is, it is preferable to introduce a gas into the reaction liquid when saponifying a vinyl ester polymer to obtain PVA.
  • vinyl ester monomers are polymerized to obtain vinyl ester polymers.
  • Methods for polymerizing vinyl ester monomers include well-known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Of these methods, bulk polymerization, which is carried out without a solvent, and solution polymerization, which is carried out using a solvent such as alcohol, are preferred, with solution polymerization, in which polymerization is carried out in the presence of a lower alcohol, being more preferred.
  • the lower alcohol alcohols having 3 or fewer carbon atoms are preferred, with methanol, ethanol, n-propanol, and isopropanol being more preferred, and methanol being even more preferred.
  • vinyl ester monomers examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate. Of these, vinyl acetate is preferred.
  • Initiators used in the polymerization reaction include known initiators such as azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); and organic peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate.
  • azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)
  • organic peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate.
  • other copolymerizable monomers can be copolymerized within the scope of the present invention.
  • examples of such other monomers include the monomers (modified species) that provide the other monomer units described above.
  • the upper limit of the amount of these other monomers used varies depending on the purpose and application of the monomers, but is preferably 20 mol%, more preferably 10 mol%, based on the total amount of monomers.
  • the upper limit of the amount of the other monomer units used may be 5 mol%, 3 mol%, 1 mol%, or 0.1 mol%.
  • the lower limit of the amount of the other monomers used may be, for example, 0.1 mol% or 1 mol%.
  • a chain transfer agent may be present to adjust the degree of polymerization of the resulting PVA.
  • chain transfer agents include aldehydes such as acetaldehyde, propionaldehyde, butyraldehyde, and benzaldehyde; ketones such as acetone, methyl ethyl ketone, hexanone, and cyclohexanone; mercaptans such as 2-hydroxyethanethiol; thiocarboxylic acids such as thioacetic acid; and halogenated hydrocarbons such as trichloroethylene and perchloroethylene. Of these, aldehydes and ketones are preferred.
  • the amount of chain transfer agent added is determined based on the chain transfer constant of the chain transfer agent and the desired degree of polymerization of the PVA, but generally, 0.1 to 10% by mass of the vinyl ester used is preferred.
  • the vinyl ester polymer is saponified in an alcohol solution using an alkaline catalyst to obtain PVA.
  • the saponification reaction of the vinyl ester polymer can be carried out by alcoholysis or hydrolysis using a conventional basic catalyst such as sodium hydroxide, potassium hydroxide, or sodium methoxide.
  • solvents that can be used in the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. These can be used alone or in combination of two or more. Among these, it is preferable to use methanol or a mixed solution of methanol and methyl acetate as the solvent and carry out the saponification reaction in the presence of sodium hydroxide, as this is simple and convenient.
  • a gas into the system (reaction liquid) during the saponification step it is preferable to introduce a gas into the system (reaction liquid) during the saponification step to obtain a solid product containing PVA and in which bubbles have formed.
  • Methods for introducing a gas into the system during the saponification step include mixing the vinyl ester polymer and alkali catalyst while entraining the gas, and directly introducing bubbles into the mixture of the vinyl ester polymer and alkali catalyst immediately before the formation of a PVA gel. It is not necessary to continuously introduce the gas into the system from start to finish of the saponification step; it is sufficient to introduce the gas into the system during at least part of the saponification step.
  • the gas introduced into the system i.e., the gas contained in the bubbles formed, is not particularly limited and may include air, nitrogen, carbon dioxide, etc., with nitrogen being preferred.
  • the number of bubble-containing particles in the resulting resin powder can be adjusted, for example, by the amount of gas introduced into the system. Furthermore, the gas can be introduced into the system through a foaming filter with a specified pore size. This makes it easier to adjust the size of the bubbles formed.
  • the pore size of the filter is preferably, for example, 1 to 300 ⁇ m, and more preferably 5 to 200 ⁇ m.
  • the solid material containing PVA obtained through the saponification process is typically washed, dried, and pulverized to obtain a resin powder.
  • the washing can be carried out using an alcohol such as methanol.
  • the drying conditions are not particularly limited, but the drying temperature can be, for example, 50°C or higher and 120°C or lower, or 60°C or higher and 100°C or lower.
  • the drying time can be, for example, 1 hour or higher and 24 hours or lower, or 2 hours or higher and 20 hours or lower, or 16 hours or lower, 12 hours or lower, or 6 hours or lower.
  • Organic volatile matter content The content of organic volatile matter in the resin powder was determined by the method described in JIS K6726:1994.
  • Number of bubble-containing particles and average bubble size Particles having a particle diameter of 106 to 1,000 ⁇ m were selected by the sieving described above, and 100 particles were randomly selected from these particles. The number of bubble-containing particles and the average bubble size were measured for these particles based on images taken at a magnification of 100 times using a digital microscope VHX-900 manufactured by Keyence Corporation.
  • Example 1 Production of PVA1 A 3-L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, and initiator addition port was charged with 1,125 g of vinyl acetate and 375 g of methanol (75% by mass of vinyl acetate: 25% by mass of methanol), and the system was purged with nitrogen for 30 minutes while bubbling with nitrogen. The reactor was heated, and when the internal temperature reached 60°C, 0.5 g of 2,2'-azobisisobutyronitrile (AIBN) was added to initiate polymerization. When the conversion reached 50%, the mixture was cooled and the polymerization was terminated. The solids concentration at the time of termination of polymerization was 37.0%.
  • AIBN 2,2'-azobisisobutyronitrile
  • Example 1 resin powder of PVA1.
  • the viscosity-average degree of polymerization of PVA1 was 1,700, the degree of saponification was 98.5 mol%, the organic volatile content of the resin powder of PVA1 was 2.7 mass%, the average particle size was 550 ⁇ m, the content of particles (predetermined particles) having a particle size of 106 to 1,000 ⁇ m was 85 mass%, the number of bubble-containing particles was 55, the average bubble size was 50 ⁇ m, the bulk density was 0.49 g/mL, and the product of the average particle size and the bulk density was 269.5 ⁇ m g/mL.
  • the value of the ratio (T/T') for the resin powder of PVA1 was 0.42.
  • the value of the ratio (T/T') was also evaluated according to the following criteria.
  • the resin powder of PVA1 was evaluated as A, and an excellent effect of improving drying efficiency due to the inclusion of air bubbles was recognized. (standard) A: Less than 0.50 B: 0.50 or more and less than 0.65 C: 0.65 or more and less than 0.75 D: 0.75 or more
  • Example 6 After 3 hours, the polymerization was terminated by cooling when the conversion reached 30%. Subsequently, saponification was carried out using the same method as in Example 1 and the conditions listed in Table 1 to produce the resin powder of Example 6 (PVA6 resin powder). Furthermore, a PVA6' resin powder was obtained under the same production conditions as for the PVA6 resin powder, but without introducing nitrogen. In the resin powder of PVA6', which was used as a standard for evaluating drying efficiency, the number of bubble-containing particles was less than 5. The resin powder of Example 6 (resin powder of PVA6) was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3. PVA6 and PVA6' were ethylene-modified PVAs, and the degree of modification was determined by 1H -NMR.
  • Example 7 A 3L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, comonomer dropping port, and initiator addition port was charged with 1200 g of vinyl acetate, 300 g of methanol, and 0.71 g of monomethyl maleate (MMM), and the system was purged with nitrogen for 30 minutes while bubbling with nitrogen. Furthermore, a comonomer solution with a concentration of 10% by mass was prepared by dissolving MMM in methanol as a delay solution, and nitrogen was purged by bubbling with nitrogen gas. The reactor temperature was then increased, and when the internal temperature reached 60°C, 1.0 g of 2,2'-azobisisobutyronitrile (AIBN) was added to initiate polymerization.
  • AIBN 2,2'-azobisisobutyronitrile
  • the delay solution was added dropwise to maintain a constant monomer composition (ratio of vinyl acetate and MMM) in the polymerization solution, and the polymerization was continued for 3 hours at 60°C. After cooling, the polymerization was terminated. Subsequently, saponification was carried out using the same method as in Example 1 and the conditions listed in Table 1, to produce the resin powder of Example 7 (PVA7 resin powder). Furthermore, a resin powder of PVA7' was obtained under the same production conditions as the resin powder of PVA7, but without introducing nitrogen. The resin powder of PVA7', which served as the standard for evaluating drying efficiency, had less than five bubble-containing particles. The resin powder of Example 7 (resin powder of PVA7) was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3. PVA7 and PVA7' were MMM-modified PVAs, and the degree of modification was determined by 1H -NMR.
  • Comparative Example 1 A resin powder of Comparative Example 1 (a resin powder of PVA8) was produced under the same conditions as in Example 1, except that the amount of nitrogen introduced was changed to 0.05 L/min.
  • the resin powder of Comparative Example 1 (a resin powder of PVA8) was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.
  • Comparative Example 2 A resin powder of Comparative Example 2 (a resin powder of PVA9) was produced under the same conditions as in Example 2, except that the amount of nitrogen introduced was changed to 0.05 L/min.
  • the resin powder of Comparative Example 2 (a resin powder of PVA9) was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.
  • the resin powder of the present invention has excellent productivity due to improved drying efficiency, and can be used for a variety of applications, including synthetic fiber raw materials, film raw materials, emulsifying dispersants, and adhesives.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

L'invention fournit une poudre de résine qui comprend un polymère à base d'alcool vinylique, et dont l'efficacité de séchage est améliorée. Plus précisément, l'invention concerne une poudre de résine qui comprend un polymère à base d'alcool vinylique, dont le diamètre particulaire moyen est compris entre １００ et ２０００μｍ, et qui présente un nombre supérieur ou égal à 10 de particules présentant des bulles supérieures ou égales à １μｍ parmi 100 particules prélevées arbitrairement parmi des particules de diamètre particulaire compris entre １０６ et １０００μｍ.
PCT/JP2025/007401 2024-03-04 2025-03-03 Poudre de résine Pending WO2025187601A1 (fr)

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JP2024-032334 2024-03-04
JP2024032334 2024-03-04

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WO2025187601A1 true WO2025187601A1 (fr) 2025-09-12
WO2025187601A8 WO2025187601A8 (fr) 2025-10-02

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TW (1) TW202547892A (fr)
WO (1) WO2025187601A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015186745A1 (fr) * 2014-06-04 2015-12-10 株式会社クラレ Poudre d'alcool polyvinylique et son procédé de production
JP2019065059A (ja) * 2016-02-10 2019-04-25 株式会社クラレ グラフト共重合体からなる粉末及びその製造方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015186745A1 (fr) * 2014-06-04 2015-12-10 株式会社クラレ Poudre d'alcool polyvinylique et son procédé de production
JP2019065059A (ja) * 2016-02-10 2019-04-25 株式会社クラレ グラフト共重合体からなる粉末及びその製造方法

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TW202547892A (zh) 2025-12-16
WO2025187601A8 (fr) 2025-10-02

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