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
  • C08F2/00—Processes of polymerisation
  • C08F2/04—Polymerisation in solution
  • C08F2/06—Organic solvent
• • 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
  • C08F118/00—Homopolymers 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 acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
  • C08F118/02—Esters of monocarboxylic acids
  • C08F118/04—Vinyl esters
  • C08F118/08—Vinyl acetate
• • 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
  • C08F14/00—Homopolymers and 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 a halogen
  • C08F14/02—Monomers containing chlorine
  • C08F14/04—Monomers containing two carbon atoms
  • C08F14/06—Vinyl chloride
• • 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
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/34—Higher-molecular-weight carboxylic acid esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/52—Natural or synthetic resins or their salts

Definitions

• the present invention relates to a polyvinyl alcohol-based resin, and more specifically, a polyvinyl alcohol-based resin suitable as a dispersant used for suspension polymerization of a vinyl-based compound during the production of polyvinyl chloride, a method for producing a polyvinyl alcohol-based resin, and a dispersant. And dispersants for suspension polymerization.
• a polyvinyl alcohol-based resin (hereinafter, "polyvinyl alcohol” may be abbreviated as "PVA") is obtained by saponifying a polymer obtained by polymerizing a vinyl ester-based monomer such as vinyl acetate. It has a vinyl alcohol structural unit corresponding to the degree of saponification and a vinyl ester structural unit remaining without saponification. Further, the PVA-based resin is dehydrated and deacetic acid by heat treatment to have a structure having a double bond in the main chain, and the PVA-based resin having such a structure is suspended during the production of polyvinyl chloride. It is used in applications such as dispersion stabilizers and water retention materials. It is also known that the strength can be improved by heat-treating a film or fiber made of a PVA-based resin.
• the double bond in the PVA-based resin acts as a starting point for adsorption to the vinyl chloride monomer and subsequent graft reaction during suspension polymerization of the vinyl chloride monomer. Therefore, the greater the number of such double bonds, the higher the polymerization stability. It is generally known to be excellent.
• Patent Document 3 In order to solve the above problems, it has been proposed to perform heat treatment using a twin-screw extruder (for example, Patent Document 3).
• the PVA-based resin described in Patent Document 3 is a polyvinyl alcohol-based resin having a carbonyl group in the molecule and a residual fatty acid ester group having a block character of 0.5 or more, and is 0.1 weight by weight of the polyvinyl alcohol resin.
• the absorbance at 215 nm, 280 nm, and 320 nm according to the ultraviolet absorption spectrum of the% aqueous solution is 0.1 or more, and the ratio of the absorbance at 320 nm / the absorbance at 280 nm is 0.3 or more.
• the above-mentioned PVA-based resin is obtained by strongly heat-treating it in order to improve the polymerization stability.
• a strongly heat-treated PVA-based resin With a strongly heat-treated PVA-based resin, the block character of the obtained PVA-based resin becomes high, so that the dispersibility decreases, and when the above-mentioned PVA-based resin is used as a dispersant for suspension polymerization, it becomes porous. There was a problem that it was difficult to obtain vinyl chloride resin.
• the present invention provides a PVA-based resin having a high content of double bonds in the resin and excellent dispersibility in order to enhance the polymerization stability of a suspended polymer (for example, polyvinyl chloride) during polymerization. It is an object of the present invention to provide a dispersant using the PVA-based resin and a dispersant for suspension polymerization used in the production of polyvinyl chloride.
• the ratio (B / A) of the absorbance (B) at 320 nm in the ultraviolet absorption spectrum when the polyvinyl alcohol-based resin is a 0.1 wt% aqueous solution to the block character (A) is 0.6 or more.
• [3] A dispersant made of the polyvinyl alcohol-based resin according to the above [1] or [2].
• [5] The above-mentioned [1] or [2], which comprises a step of polymerizing a monomer composition containing a vinyl ester-based monomer while introducing a gas containing oxygen to obtain a vinyl ester-based polymer.
• a PVA-based resin having a high content of double bonds in the resin and a small block character value can be obtained. Therefore, when such a PVA-based resin is used as a dispersant for suspension polymerization, the polymerization stability of the suspension polymerization (for example, polyvinyl chloride) can be improved, and the dispersion stability can also be improved. It is presumed.
• the polyvinyl alcohol-based resin of the present invention will be described in detail, but these are examples of desirable embodiments and are not specified in these contents.
• the weight-based ratio (percentage, parts, etc.) is the same as the mass-based ratio (percentage, parts, etc.).
• the polyvinyl alcohol-based resin of the present invention (hereinafter referred to as PVA-based resin) has a block character (A) of less than 0.4 and absorbs ultraviolet rays when the polyvinyl alcohol-based resin is made into a 0.1 wt% aqueous solution.
• the absorbance (B) at 320 nm in the spectrum is 0.2 or more.
• the PVA-based resin of the present invention has a block character (A) of less than 0.4, preferably 0.25 or more and less than 0.4, more preferably 0.3 or more and less than 0.4, and further preferably 0. It is 35 or more and less than 0.4.
• the block character (A) is less than 0.4, the dispersion stability ability of the PVA-based resin is improved. If the value of the block character (A) is too large, the plasticizer absorbability of the vinyl resin obtained by suspension polymerization is lowered or the particle size is reduced when the PVC resin is used as the dispersant for suspension polymerization. The distribution tends to be wide, and if the value of (A) is too small, the polymerization stability tends to deteriorate.
• Such block character (A) is a 3- (trimethylsilyl) -2,2,3,3-d 4 -propionate sodium salt (3- (trimethylsilyl) productic-2,2,3,3-d as an internal standard substance.
• Block character (A) (OH, OR) / 2 (OH) (OR) (However, (OH, OR), (OH), and (OR) are all calculated by mole fraction.
• (OH) is the degree of saponification calculated by the integration ratio of 13 C-NMR.
• Mole fraction for example, when vinyl acetate is used as the fatty acid vinyl, (OR) indicates the mole fraction of the acetoxy group at that time.
• the block character indicates the degree of the average chain length of the fatty acid ester unit in the polyvinyl alcohol resin, and the larger the value, the shorter the average chain length of the remaining fatty acid ester block (the randomness of the fatty acid ester unit is). (High) is shown.
• the block character and its measurement method are described in detail in Povar (Publisher: Polymer Publications, 1984) and Macromolecules, 10,532 (1977).
• the absorbance (B) at 320 nm in the ultraviolet absorption spectrum when the PVA-based resin of the present invention is a 0.1% by weight aqueous solution is 0.2 or more, preferably 0.25 or more, and more preferably 0.30. That is all.
• the value of the absorbance (B) is at least the above lower limit value, the amount of double bonds of the PVA-based resin tends to be sufficient, and the polymerization stability when the PVA-based resin is used as a dispersant for suspension polymerization. Is improved.
• the upper limit is not particularly limited, but is about 1.5 from the viewpoint of manufacturability.
• the value of the absorbance (B) is too small, the formation of double bonds in the PVA-based resin is small, and therefore, when the PVA-based resin is used as various dispersants, the surface activity tends to decrease. Further, if the value of the absorbance (B) is too large, the average particle size of the obtained polyvinyl chloride or the like becomes too small when the PVA-based resin is used as a dispersant for suspension polymerization, resulting in poor handleability. Tends to be.
• the ratio (B / A) of the absorbance (B) at 320 nm in the ultraviolet absorption spectrum when the PVA-based resin of the present invention is a 0.1 wt% aqueous solution to the block character (A) is 0. It is preferably .5 or more, and more preferably 0.6 or more.
• (B / A) is at least the above lower limit value, the polymerization stability is improved when used as a dispersant for suspension polymerization, which is preferable. If the ratio (B / A) is too small, the surface activity ability tends to be low and the suspension polymerization stability tends to be lowered when used as a dispersant for suspension polymerization such as vinyl chloride.
• the upper limit is not particularly limited, but is about 3 from the viewpoint of productivity.
• the absorbance of a 0.1 wt% aqueous solution of a PVA-based resin is measured using an ultraviolet-visible near-infrared spectrophotometer (for example, "V-560" (trade name) manufactured by JASCO Corporation). It is a value obtained by.
• the absorbance is measured using a sample container (cell) having an optical path length of 1 cm.
• the PVA-based resin is a homopolymer of a vinyl ester-based monomer or a copolymer of a vinyl ester-based monomer and another monomer (hereinafter, these are referred to as "vinyl ester-based polymers". It is a resin obtained by saponifying) with an alkali catalyst or the like.
• the saponification degree of the PVA-based resin of the present invention is preferably 60 mol% or more, more preferably 65 to 98 mol%, more preferably 67 to 90 mol%, still more preferably 69 to 88 mol%, in particular. It is preferably 70 to 82 mol%. Since the PVA-based resin of the present invention has an acetic acid group (hydrophobic group) in addition to a hydroxyl group (hydrophilic) in the molecule, it has a surface active ability and can be uniformly dispersed in a dispersion medium. If the saponification degree is too low, the water dispersibility tends to decrease. Therefore, the saponification degree is preferably 60 mol% or more. The saponification degree is a value measured in accordance with JIS K 6726: 1994.
• the average degree of polymerization of the PVA-based resin of the present invention is preferably 100 to 4000, more preferably 200 to 3000, and particularly preferably 200 to 2000. If the average degree of polymerization is too low, the surface activity tends to be low, and when used as a dispersant for suspension polymerization of vinyl chloride, aggregation is likely to occur during suspension polymerization. On the contrary, if the average degree of polymerization is too high, the viscosity of the PVA-based resin aqueous solution increases, and the handleability tends to decrease.
• the average degree of polymerization can be measured in accordance with JIS K 6726: 1994.
• a PVA-based resin heat-treated to make the amount of double bonds in the resin sufficient is prone to yellowing, and is obtained when such a PVA-based resin is used as a dispersant for suspension polymerization.
• the hue of a resin such as vinyl chloride may deteriorate.
• the PVA-based resin of the present invention when the PVA-based resin of the present invention is obtained, the content of double bonds can be relatively increased without heat treatment, so that the PVA-based resin of the present invention tends to have a relatively small YI value and suppresses yellowing. Easy to excel.
• the PVA-based resin of the present invention has a block character (A) of less than 0.4 and has an absorbance of 320 nm in the ultraviolet absorption spectrum when the PVA-based resin is used as a 0.1 wt% aqueous solution.
• B) is 0.2 or more.
• a method for obtaining a PVA-based resin having a block character (A) of less than 0.4 and an absorbance (B) of 320 nm in an ultraviolet absorption spectrum of a 0.1 wt% aqueous solution of 0.2 or more will be described. ..
• Examples of such a method include the following methods (i) to (iv).
• (Ii) A method of radically polymerizing a monomer composition containing a vinyl ester-based monomer in the coexistence of oxygen and an aldehyde, and saponifying the obtained vinyl ester-based polymer.
• (Iii) A method of reacetic acidizing a vinyl alcohol-based resin having a double bond and saponifying the obtained vinyl ester-based polymer.
• (Iv) A method in which a monomer composition containing a vinyl ester-based monomer is radically polymerized in the coexistence of formaldehyde, and the obtained vinyl ester-based polymer is saponified.
• the method (i) or (ii) described above is preferable from the viewpoint of productivity.
• the monomer composition as a starting material contains a vinyl ester-based monomer.
• Vinyl ester-based monomers include, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl palmitate, vinyl stearate and other linear or branched saturated fatty acids. Vinyl ester and the like can be mentioned. From a practical point of view, it is preferable to use vinyl acetate as the vinyl ester-based monomer. For example, it is preferable to use vinyl acetate alone or in combination with vinyl acetate and a fatty acid vinyl ester compound other than vinyl acetate. ..
• the polymerization of the monomer composition containing the vinyl ester-based monomer there are no particular restrictions on the polymerization of the monomer composition containing the vinyl ester-based monomer, and a known polymerization method can be arbitrarily used.
• solution polymerization is carried out using an alcohol having 1 to 3 carbon atoms such as methanol, ethanol or isopropyl alcohol as a solvent.
• alcohol having 1 to 3 carbon atoms such as methanol, ethanol or isopropyl alcohol
• bulk polymerization, emulsion polymerization, and suspension polymerization are also possible.
• any means such as split charging and batch charging may be used as the method for charging the vinyl ester-based monomer.
• the polymerization reaction is carried out using known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, azobisdimethylvaleronitrile and azobismethoxyvaleronitrile.
• the polymerization reaction temperature is selected from the range of 40 ° C. to about boiling point.
• the step of polymerizing the monomer composition containing the vinyl ester-based monomer to obtain the vinyl ester-based polymer is preferably carried out under conditions containing oxygen.
• a vinyl ester-based polymer is obtained by polymerizing a monomer composition containing a vinyl ester-based monomer while introducing a gas containing oxygen or before polymerization. Is preferable, and it is more preferable to polymerize the monomer composition containing the vinyl ester-based monomer while introducing a gas containing oxygen to obtain a vinyl ester-based polymer.
• the method for introducing the gas containing oxygen is not particularly limited, but for example, introduction by blowing (bubbling) is preferable.
• a PVA-based resin having a relatively large absorbance (B) and a relatively small block character (A) value can be obtained. Furthermore, since the content of the double bond can be made relatively large without undergoing heat treatment, the obtained PVA-based resin and the resin obtained when the PVA-based resin is used as a dispersant for suspension polymerization Yellowing is less likely to occur. Therefore, according to the method for producing a PVA-based resin of the present invention, a PVA-based resin having excellent polymerization stability and dispersion stability and excellent yellowing suppression when used as a dispersant for suspension polymerization can be obtained.
• the method for introducing the gas containing oxygen can be arbitrarily selected, but it is preferable to introduce a gas diluted with an inert gas such as nitrogen, argon or helium so that the oxygen concentration becomes 1% by mass to 9% by mass. .. If the oxygen concentration is less than 1% by mass, a sufficient amount of oxygen is not introduced into the reaction field, and it tends to be difficult to obtain PVA having the desired formyl end. If it exceeds 9% by mass, the explosive limit oxygen concentration of vinyl acetate (9 to 10% by mass) is reached or exceeded, so that safety concerns are likely to occur.
• an inert gas such as nitrogen, argon or helium
• the method of introducing a gas containing oxygen into the reaction system can be arbitrarily selected, but the method of performing polymerization using a polymerization solution directly bubbled to the polymerization solution or performing polymerization while directly bubbling the polymerization solution is in the reaction system. Since the contact area between and oxygen can be increased, the introduction efficiency is good.
• the amount of oxygen to be introduced can be arbitrarily selected, but the amount of oxygen supplied per minute with respect to the amount of monomer is preferably 25 mL or less. If it exceeds 25 mL, it is not preferable in terms of productivity. Moreover, since the reaction efficiency tends to deteriorate when the amount is 0.1 mL or less, the oxygen supply amount is preferably 0.1 mL or more.
• the introduction time of the gas containing oxygen is preferably 0 to 3 hours, preferably 15 minutes to 1 hour, although it depends on the size of the manufacturing equipment and the flow rate of the gas. More preferred.
• a chain transfer agent in the polymerization of the monomer composition.
• the chain transfer agent include ethanol, methanol, 1-propanol and the like as alcohols
• aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde and benzaldehyde as ketones.
• acetone, methyl ethyl ketone, hexanone, cyclohexanone and the like can be mentioned.
• alcohols and / or aldehydes are preferably used, and methanol and acetaldehyde are particularly preferable, because the structure after polymerization is similar to that of the final product.
• the amount of the chain transfer agent added varies slightly depending on the chain transfer constant of the chain transfer agent to be added, the degree of polymerization of the target PVA-based resin, etc., but any amount can be added.
• the amount of the chain transfer agent added is usually preferably 0.1 to 200% by weight, more preferably 0.5 to 150% by weight, still more preferably 1. It is 0 to 130% by weight, particularly preferably 1.3 to 100% by weight.
• the method of charging the chain transfer agent may be an initial batch preparation or may be charged at the time of the polymerization reaction. By charging the chain transfer agent by any method, the molecular weight distribution of the PVA-based resin can be controlled.
• the vinyl ester-based monomer may be used alone, but if necessary, the vinyl ester-based monomer and the vinyl ester-based monomer and the polymerizable monomer are combined.
• the PVA-based resin of the present invention is a modified PVA-based resin obtained by using a vinyl ester-based polymer obtained by copolymerizing a vinyl ester-based monomer with a vinyl ester-based monomer and a polymerizable monomer. It may be.
• Examples of the monomer polymerizable with the vinyl ester-based monomer include vinyl groups such as glycidyl (meth) acrylate, glycidyl (meth) allyl ether, 3,4-epoxycyclohexyl (meth) acrylate, and allyl glycidyl ether.
• Monomer having an epoxy group monomer having two or more allyl groups such as triallyloxyethylene, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane, diallyl phthalate, etc .; allyl acetate , Allyl ester-based monomers such as acetoacetic acid vinyl ester, acetoacetate allyl ester, diacetacetate allyl ester; acetoacetoxyalkyl (meth) acrylate such as acetoacetoxyethyl (meth) acrylate, acetoacetoxypropyl (meth) acrylate; Acetoxyethyl crotonate, acetoacetoxypropyl crotonate, etc.
• acetoacetoxyalkyl crotonate 2-cyanoacetoacetoxyethyl (meth) acrylate; divinylbenzene; ethylene glycol di (meth) acrylate, 1,2-propylene glycol di (meth) Alkylene glycols such as acrylate, 1,3-propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate.
• olefins such as ethylene, propylene, 1-butene, isobutene; halogenated olefins such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride; olefin-based monomers such as ethylene sulfonic acid; butadiene-1,3 , 2-Methylbutadiene, 1,3 or 2,3-dimethylbutadiene-1,3,2-chlorobutadiene-1,3 and other diene-based monomers; 3-butene-1-ol, 4-pentene-1 -All, 5-Hexen Hydroxy group-containing ⁇ -olefins such as -1,2-diol and glycerin monoallyl ether, and derivatives such as acylated products thereof; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2- Hydroxymethylvinylidene diacetates such as methyleneprop
• Amids such as nitriles, methacrylamides and diacetoneacrylamides, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid and AMPS (2-acrylamide-2-methylpropan sulfonic acid) or salts thereof.
• vinylalkyldialkoxysilanes such as vinyltriethoxysilane, vinyltrimethoxysilane, vinyltripropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane; ⁇ - (meth) acryloxipropyltrimethoxy ⁇ - (meth) acryloxypropyltrialkoxysilane such as silane, ⁇ - (meth) acryloxypropyltriethoxysilane; ⁇ - (meth) acryloxypropylmethyldimethoxysilane, ⁇ - (meth) acryloxipropylmethyldiethoxy.
• Examples thereof include ⁇ - (meth) acryloxipropylalkyldialkoxysilane such as silane; vinyltris ( ⁇ -methoxyethoxy) silane and hydroxymethylvinylidene diacetate.
• ⁇ - (meth) acryloxipropylalkyldialkoxysilane such as silane
• vinyltris ( ⁇ -methoxyethoxy) silane and hydroxymethylvinylidene diacetate.
• hydroxymethylvinylidene diacetate include 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyronyloxy-2-methylenepropane. And so on.
• (meth) acrylate means “acrylate and / or methacrylate”, and the same applies to "(meth) allyl” and “(meth) acrylo”.
• the content of the vinyl ester-based monomer and the polymerizable monomer is preferably 20 mol% or less, and more preferably 10 mol% or less in the monomer composition.
• Saponification can be carried out by a known method, and is usually carried out in the presence of an alkali catalyst or an acid catalyst by dissolving the vinyl ester polymer in alcohol and ester.
• the alcohol include alcohols having 1 to 6 carbon atoms such as methanol, ethanol and butanol.
• the ester include esters having 3 to 8 carbon atoms such as methyl acetate, ethyl acetate, and butyl acetate.
• the alcohol and ester used during saponification can be used in any combination, but from the viewpoint of productivity, methanol and methyl acetate are preferably used.
• the concentration of the vinyl ester polymer in the alcohol and the ester is preferably selected from the range of 1 to 70% by weight from the viewpoint of solubility.
• an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, or an alkali catalyst such as alcoholate
• an aqueous inorganic acid solution such as hydrochloric acid or sulfuric acid, or an organic acid such as p-toluenesulfonic acid
• the amount of such a catalyst used is preferably 1 to 100 mmol equivalent, more preferably 1 to 40 mmol equivalent, and even more preferably 1 to 30 mmol equivalent with respect to the vinyl ester monomer.
• the reaction temperature at the time of saponification is not particularly limited, but is preferably, for example, 10 to 70 ° C, and more preferably selected from the range of 20 to 50 ° C.
• the PVA-based resin of the present invention may be a modified PVA-based resin obtained by post-modifying the obtained PVA-based resin.
• Examples of the method for producing a modified PVA-based resin by post-modification include a method of acetoacetate esterification, acetalization, urethanization, etherification, grafting, phosphoric acid esterification, and oxyalkyleneization of a PVA resin. Be done.
• the PVA-based resin obtained by saponification is then dried, and the PVA-based resin obtained by such saponification includes at least one of a salt and a hydroxide of a divalent or trivalent metal. One may be contained.
• Examples of the divalent to trivalent metal include magnesium, calcium, zinc, aluminum and the like.
• Specific examples of these metal salts or hydroxides include magnesium acetate tetrahydrate, calcium acetate, calcium propionate, magnesium butyrate, magnesium carbonate, magnesium hydroxide, zinc acetate, aluminum hydroxide and the like.
• One type may be used alone, or two or more types may be used in combination.
• magnesium acetate tetrahydrate and calcium acetate are preferable because they are soluble in water and / or methanol and are easy to handle industrially.
• the method of containing a salt and / or a hydroxide of a divalent or trivalent metal is not limited, and for example, the above compound may be directly added to a paste before saponification, a slurry after saponification, or the like.
• it is dissolved in alcohol such as methanol, ethanol, propanol, or water, and added to a slurry of PVA-based resin after saponification in the form of a solution having a concentration of about 3 to 15% by weight, and distributed to PVA-based resin.
• alcohol such as methanol, ethanol, propanol, or water
• the PVA-based resin obtained as described above is saponified and then dried to become a powdery PVA-based resin.
• the drying method include vacuum drying, normal pressure drying, hot air drying and the like.
• the drying time is usually 10 minutes to 20 hours, preferably 1 hour to 15 hours, and the drying temperature is usually 40 to 140 ° C., more preferably 40 to 120 ° C., particularly preferably 50 ° C. or higher and 100 ° C. Is less than.
• the PVA-based resin of the present invention obtained as described above has excellent hue because coloring (yellowing) is suppressed, and can be suitably used for various purposes.
• Applications of the PVA-based resin of the present invention include, for example, the following.
• Mold-related products Fibers, films, sheets, pipes, tubes, leak-proof films, provisional films, chemical laces, water-soluble fibers, etc.
• Adhesives Adhesives for wood, paper, aluminum foil, plastics, etc., adhesives, re-wetting agents, binders for non-woven fabrics, binders for various building materials such as gypsum board and fiberboard, binders for powder granulation , Additives for cement and mortar, hot melt type adhesives, pressure sensitive adhesives, adhesives for anionic paints, etc.
• Coating agents Clear coating agent for paper, pigment coating agent for paper, internal sizing agent for paper, sizing agent for textile products, warp paste, textile processing agent, leather finishing agent, paint, antifogging agent, Metal corrosion inhibitor, brightener for zinc plating, antistatic agent, conductive agent, provisional paint, etc.
• Blending agents for hydrophobic resins Antistatic agents for hydrophobic resins, hydrophilicity-imparting agents, composite fibers, films and other additives for molded products, etc.
• Dispersant-related Dispersant for color developer of coating liquid for heat-sensitive color-sensitive layer, paint, ink, water-based color, pigment dispersion stabilizer such as adhesive, vinyl chloride, vinylidene chloride, styrene, (meth) acrylate , Dispersion stabilizer for suspension polymerization of various vinyl compounds such as vinyl acetate.
• Emulsion dispersion stabilizer-related various acrylic monomers, ethylenically unsaturated compounds, emulsifiers for emulsion polymerization of butadiene compounds, hydrophobic resins such as polyolefins and polyester resins, post-emulsifiers such as epoxy resins, paraffins and bitumens.
• Thickener-related Thickeners for various aqueous solutions, emulsions, petroleum drilling fluids, etc.
• Coagulant-related Coagulants for suspensions and dissolved substances in water, drainage agents for pulp and slurries, etc.
• Exchange resin, etc . Ion exchange resin, chelate exchange resin, ion exchange membrane, etc.
• the PVA-based resin of the present invention is particularly useful as a dispersion stabilizer for suspension polymerization of various vinyl compounds such as vinyl acetate and vinyl chloride, and particularly as a dispersion stabilizer for suspension polymerization of vinyl chloride compounds. It is useful.
• the PVA-based resin of the present invention When the PVA-based resin of the present invention is used as a dispersant, examples of the dispersant include polymerizable monomers and powders.
• the PVA-based resin of the present invention is particularly preferably used as a dispersant for suspension polymerization using a polymerizable monomer as a dispersion.
• examples of the polymerizable monomer to be suspended polymerization include vinyl chloride, vinylidene halide, vinyl ether, vinyl acetate, vinyl benzoate, acrylic acid, methacrylic acid, maleic acid or its anhydride, ethylene, propylene, styrene and the like. Can be mentioned.
• the PVA-based resin of the present invention is suitably used for homopolymerization of vinyl chloride or copolymerization of vinyl chloride and a monomer copolymerizable with vinyl chloride.
• the amount of the PVA-based resin used in the present invention may be appropriately adjusted according to the monomer to be suspended-polymerized. For example, when it is used for suspension polymerization of a vinyl chloride-based monomer, for example, a vinyl chloride-based resin is used. It is preferably used in an amount of 5 parts by weight or less with respect to 100 parts by weight of the monomer, more preferably 0.01 to 1 part by weight, still more preferably 0.02 to 0.2 parts by weight. If the amount used is too large, the amount of PVA-based resin that does not act as a dispersant tends to increase.
• the PVA-based resin of the present invention is added as a dispersant to water or a heated water medium, and a vinyl chloride-based monomer is dispersed to carry out the polymerization in the presence of an oil-soluble catalyst. Is preferable.
• the powder is added as it is in the state of water, an organic solvent such as alcohol, ketone, ester, etc., or a solution in which the PVA-based resin is dissolved in a mixed solvent of these organic solvents and water.
• an organic solvent such as alcohol, ketone, ester, etc.
• a solution in which the PVA-based resin is dissolved in a mixed solvent of these organic solvents and water examples thereof include a method and a method of adding the PVA-based resin in the state of a dispersion in which the PVA-based resin is dispersed in the above solvent.
• the timing of addition it may be added all at once at the initial stage of polymerization, or may be added separately in the middle of polymerization.
• polymer substances can be used in combination.
• the polymer substance include PVA-based resins other than the PVA-based resin of the present invention.
• PVA-based resin unmodified PVA, the above-mentioned modified PVA-based resin, and the like can be used.
• polymerization aid examples include various surfactants and inorganic dispersants, and the PVA-based resin of the present invention can also be used as the polymerization aid.
• the polymerization catalyst may be any oil-soluble catalyst, for example, benzoyl peroxide, lauroyl peroxide, diisopropylperoxydicarbonate, ⁇ , ⁇ '-azobisisobutyronitrile, ⁇ , ⁇ '-azobis-2. , 4-Dimethyl-Valeronitrile, acetylcyclohexylsulfonyl peroxide or mixtures thereof are used.
• Example 1 [Manufacture of PVA-based Resin (PVA-1) of the Present Invention] 100 parts by weight of vinyl acetate and 100 parts by weight of methanol are charged in a polymerization can, and heated while supplying an oxygen / nitrogen (5:95, volume ratio) mixed gas to the liquid phase at 120 mL / min, vinyl acetate is heated at a boiling point. 0.4% by weight of azobisisobutyronitrile (AIBN) was charged into a polymerization can and polymerization was started. The polymerization was stopped when the polymerization rate reached 73.2% by weight after about 7 hours of the reaction time. Then, unpolymerized vinyl acetate was removed and saponified by a conventional method to obtain a PVA-based resin (polymerization degree 590, saponification degree 71.8 mol%).
• AIBN azobisisobutyronitrile
• YI value ⁇ Measurement of yellow index (YI value)> A 0.1% aqueous solution of PVA-based resin (PVA-1) was prepared. The YI value of such an aqueous solution was measured using a colorimeter "CM-3600A” (trade name) manufactured by Konica Minolta Co., Ltd. The results are shown in Table 1.
• Example 2 Manufacture of PVA-based Resin (PVA-2) of the Present Invention
• 100 parts by weight of vinyl acetate, 2.0 parts by weight of acetaldehyde, and 4.9 parts by weight of methanol are charged in a polymerization can, and heated while supplying an oxygen / nitrogen (5:95, volume ratio) mixed gas to the liquid phase at 120 mL / min.
• an oxygen / nitrogen (5:95, volume ratio) mixed gas to the liquid phase at 120 mL / min.
• AIBN azobisisobutyronitrile
• Sodium acetate is added to a saponified slurry of a PVA-based resin (polymerization degree 630, saponification degree 71.7 mol%) having a resin content of 12% so that the amount of sodium acetate after shaking off is 1% by weight based on the PVA-based resin. In addition, it was shaken off. Next, a 20% methanol solution of magnesium acetate tetrahydrate as a metal compound was added to the PVA-based resin prepared above so that magnesium acetate was 2% by weight based on the PVA-based resin, and then dried to acetic acid. A PVA-based resin containing 2% by weight of magnesium and 1% by weight of sodium acetate was obtained.
• the obtained resin was heat-treated at 140 ° C. to obtain a PVA-based resin (PVA-3).
• PVA-3 the block character (A 3 ), the ultraviolet absorption spectrum at 320 nm (B 3 ), and the YI value were measured in the same manner as in Example 1. The results are shown in Table 1.
• Sodium acetate is added to a saponified slurry of a PVA-based resin (polymerization degree 630, saponification degree 71.7 mol%) having a resin content of 12% so that the amount of sodium acetate after shaking off is 1% by weight based on the PVA-based resin. In addition, it was shaken off. Next, a 20% methanol solution of magnesium acetate tetrahydrate as a metal compound was added to the PVA-based resin prepared above so that magnesium acetate was 2% by weight based on the PVA-based resin, and then dried to obtain acetic acid. A PVA-based resin (PVA-5) containing 2% by weight of magnesium and 1% by weight of sodium acetate was obtained. With respect to the obtained PVA-based resin (PVA-5), the block character (A 5 ), the ultraviolet absorption spectrum at 320 nm (B 5 ), and the YI value were measured in the same manner as in Example 1. The results are shown in Table 1.
• the PVA-based resins of Examples 1 and 2 can achieve both a high double bond amount and a small block character value as compared with the PVA-based resins of Comparative Examples 1 to 3.
• the PVA-based resins of Examples 1 and 2 have a lower YI value than the PVA-based resins of Comparative Example 1 in which the amount of double bonds is relatively close.
• a PVA-based resin having excellent polymerization stability, dispersibility and yellowing suppression during polymerization was obtained.
• the PVA-based resin of the present invention Since the PVA-based resin of the present invention has a large amount of double bonds, it has excellent suspension polymerization stability when used as a dispersant for suspension polymerization, and further, when used as various dispersants, during polymerization. Excellent polymerization stability. Further, since the value of the block character is small, the PVA-based resin of the present invention has high surface activity and excellent dispersibility when used as various dispersants. The PVA-based resin of the present invention is particularly useful as a dispersant for suspension polymerization of vinyl chloride-based monomers.

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• 2021
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