JP6260933B2 - Emulsifier for emulsion polymerization - Google Patents

Description

  The present invention relates to an emulsifier for emulsion polymerization, which is excellent in emulsion stability during polymerization, and excellent in low foamability and wettability of the resulting polymer emulsion.

  In the field of synthetic resins represented by rubber and plastic industrial products, the shift from solvent-based to water-based polymer emulsion is progressing due to the recent needs for reducing environmental impact. Polymer emulsions are used in a wide range of fields such as paints, adhesives, civil engineering, and fibers, and an emulsifier for emulsion polymerization used in producing polymer emulsions plays an important role.

  Conventionally, various nonionic surfactants are used alone or in combination of two or more as emulsifiers for emulsion polymerization. For example, as an alkylphenyl ether type surfactant in which an alkylene oxide such as ethylene oxide is added to an alkylphenyl ether, it is proposed to use an ethylene oxide adduct of nonylphenol having an HLB of more than 8-12 and up to 12 to 16. (Patent Document 1). In general, alkylphenyl ether type surfactants using octylphenol, nonylphenol and the like have been widely used because of their excellent emulsifiability, no adverse effects on resin polymerization, and low cost. However, due to concerns about impacts on living organisms and the environment, they are shifting to aliphatic alcohols without using alkylphenols. In addition, alkylphenyl ether type surfactants have a problem of easily foaming. For example, when it is used as a paint, if the resulting polymer emulsion tends to foam, defects such as pinholes occur on the coated surface, and a uniform coating film cannot be obtained, causing the appearance of the painted surface to be impaired.

  As an alternative to the alkylphenyl ether type surfactant, a C10 alcohol having at least 3 methyl groups is used, and a compound obtained by adding ethylene oxide or a sulfated compound is used as an emulsifier for emulsion polymerization. (Patent Document 2). This compound has an emulsifying property during polymerization equivalent to that of an alkylphenyl ether type surfactant. However, the obtained polymer emulsion still has a problem of easily foaming.

  For example, when it is used as an adhesive for electronic parts, a polymer emulsion that can be applied more finely and uniformly is demanded as the substrate to be applied is downsized. Therefore, as the performance required for the polymer emulsion, not only low foamability but also excellent wettability is required. If the adhesive is liable to foam or if the wettability is insufficient, a portion where the adhesive is not applied is generated, which causes a decrease in adhesive strength.

  Therefore, a nonionic active agent having a polydispersity of 1.10 to 1.20 obtained by adding propylene oxide or ethylene oxide to an alcohol having a branching degree of 1.8 to 2.4 and having 10 carbon atoms is emulsified. It has been proposed to use as an emulsifier for polymerization (Patent Document 3). This compound is not only excellent in emulsion stability during polymerization, but also can provide a polymer emulsion having low foaming properties. However, the low foaming property is insufficient, and in addition, there is a problem that the wettability is inferior.

  Therefore, an emulsifier for emulsion polymerization that is excellent in both the emulsion stability during polymerization and the low foamability and wettability of the resulting polymer emulsion has been desired.

JP-A-5-170805 JP 2002-308912 A JP 2006-348254 A

  The subject of this invention is providing the emulsifier for emulsion polymerization which is excellent in both the emulsion stability at the time of superposition | polymerization, and the low-foaming property and wettability of the polymer emulsion obtained.

  As a result of intensive studies in order to achieve the above object, as a result of using a compound having a structure in which an oxyethylene group or an oxypropylene group is added to a specific alcohol at a specific ratio, the emulsion stability during polymerization is excellent. In addition, the polymer emulsion obtained has been found to be excellent in low-foaming property and wettability, leading to the present invention.

That is, the emulsifier for emulsion polymerization according to the present invention is obtained by adding 20 to 110 parts by weight of the compound represented by the formula (2) to 100 parts by weight of the compound represented by the formula (1). .

_{^{R 1 O- (AO) a -}} (PO) b -H (1)

(In the formula (1), R ¹ is an alkyl group having 9 carbon atoms, AO is an oxyethylene group or an oxypropylene group, a is the sum of the average added moles of AO, and a = 10 to 35 (AO) 70% by weight or more of (AO) _a is occupied by oxyethylene groups, PO is an oxypropylene group, b is the average number of moles of PO added, and b = 3 to 5, / B = 3-12.)

_{^{R 2 O- (EO) c -}} (PO) d -H (2)

(In the formula (2), R ² is an alkyl group having 9 carbon atoms, EO is an oxyethylene group, PO is an oxypropylene group, c is an average added mole number of EO, and c = 2 to 2. 9 and d is the average number of moles of PO added, d = 2-4, and c / d = 0.6-3.)

  The emulsifier for emulsion polymerization is characterized in that AO of the compound represented by the formula (1) is an oxyethylene group.

  According to the present invention, an emulsifier for emulsion polymerization which is excellent in both the emulsion stability during polymerization and the low foamability and wettability of the resulting polymer emulsion is very useful.

(Compound represented by Formula (1))
R ¹ is an alkyl group having 9 carbon atoms, and is a residue obtained by removing a hydroxyl group from a linear or branched alcohol having 9 carbon atoms. Specifically, a linear n-nonyl group derived from n-nonanol, an isononyl group derived from isononyl alcohol having a methyl branch obtained by an oxo method using n-butene or isobutylene as a raw material, Examples include 3,5,5-trimethylhexyl group derived from 5-trimethyl-1-hexanol. Of the alkyl groups having 9 carbon atoms, isononyl groups having a methyl branch and 3,5,5-trimethylhexyl groups are preferred. In particular, the emulsion stability during polymerization and the low foamability and wettability of the resulting polymer emulsion From the viewpoint, a 3,5,5-trimethylhexyl group having three methyl branches is most preferable.

When R ¹ has 8 or less carbon atoms, the emulsion stability during polymerization and the wettability of the resulting polymer emulsion are inferior.

  AO is an oxyethylene group or an oxypropylene group. In AO, the oxyethylene group and the oxypropylene group may be used in combination, or may be composed of only the oxyethylene group.

  When an oxyethylene group and an oxypropylene group are used in combination, a block adduct or a random adduct may be used. When an oxyethylene group and an oxypropylene group are used in combination, a random adduct is particularly preferable from the viewpoint of improving the handling property by lowering the freezing point of the compound represented by the formula (1).

Moreover, when using together an oxyethylene group and an oxypropylene group, the ratio of the oxyethylene group of (AO) _a part is 70 weight% or more. When the proportion of oxyethylene groups is less than 70% by weight, the emulsifying properties are lowered, and solids are liable to precipitate or gel during polymerization. From this viewpoint, the proportion of the oxyethylene group in the (AO) _a portion is preferably 70 to 90% by weight, and more preferably 70 to 85% by weight.

  The oxypropylene group is a propylene oxide-derived oxypropylene group (methyloxyethylene group).

  a is the average added mole number of AO (oxyethylene group or oxypropylene group). When AO contains both an oxyethylene group and an oxypropylene group, a shows the sum total of each average addition mole number.

  a is 10 to 35. When a is less than 10, the emulsifying property is lowered, and it becomes easy to cause precipitation and gelation of solids during polymerization. From the viewpoint of reducing the freezing point of the compound represented by the formula (1) and improving the handleability, a is more preferably 12 or more, and more preferably 15 or more. Further, when a exceeds 35, the handling property is lowered due to an increase in viscosity or the influence of the freezing point, and therefore a is preferably 30 or less, and more preferably 20 or less.

  PO is an oxypropylene group and is an oxypropylene group (methyloxyethylene group) derived from propylene oxide. b is an average addition mole number of an oxypropylene group, is 3-5, and 3-4 are more preferable. When b is smaller than 3, the resulting polymer emulsion is inferior in low foaming property and wettability, which is not preferable. On the other hand, when b is larger than 5, the emulsifying property is lowered, and it is easy to cause precipitation or gelation of solids during polymerization, which is not preferable.

  a / b is a ratio of the average added mole number a of AO to the average added mole number b of PO, and is 3-12. When a / b is smaller than 3, the emulsifying property is lowered, and it becomes easy to cause precipitation and gelation of solids during polymerization. From this viewpoint, a / b is more preferably 5 or more. Moreover, when a / b is larger than 12, it is not preferable because the resulting polymer emulsion is inferior in low foaming property and leveling property. From this viewpoint, a / b is 12 or less, but 10 or less is more preferable.

  In addition, the compound represented by Formula (1) may be used independently, or may use 2 or more types together.

(Compound represented by Formula (2))
R ² is an alkyl group having 9 carbon atoms, and is a residue obtained by removing a hydroxyl group from a linear or branched alcohol having 9 carbon atoms. Specifically, a linear n-nonyl group derived from n-nonanol, an isononyl group derived from isononyl alcohol having a methyl branch obtained by an oxo method using n-butene or isobutylene as a raw material, Examples include 3,5,5-trimethylhexyl derived from 5-trimethyl-1-hexanol. Of the alkyl groups having 9 carbon atoms, isononyl groups having a methyl branch and 3,5,5-trimethylhexyl groups are preferred. In particular, the emulsion stability during polymerization and the low foamability and wettability of the resulting polymer emulsion From the viewpoint, a 3,5,5-trimethylhexyl group having three methyl branches is most preferable.

When R ² is 8 or less carbon atoms, emulsion stability and the time of polymerization is not preferable because the wettability of the resulting polymer emulsion is poor.

  EO is an oxyethylene group. c is an average addition mole number of an oxyethylene group, and is set to 2-9. When c is larger than 9, it is not preferable because low foamability and wettability of the polymer emulsion to be obtained are lowered. c is preferably from 2 to 8, and more preferably from 2 to 5.

  PO is an oxypropylene group and is an oxypropylene group (methyloxyethylene group) derived from propylene oxide. d is the average number of moles of PO added and is 2-4. When d is smaller than 2, it is not preferable because the resulting polymer emulsion is inferior in low foaming property and wettability. On the other hand, when d is larger than 4, the emulsifiability is lowered, and it is easy to cause solid precipitation or gelation during polymerization. As for d, 3-4 are more preferable.

  c / d is the ratio of the average added mole number c of EO to the average added mole number d of PO, and is 0.6-3. When this is smaller than 0.6, the emulsifying property is lowered, and it is not preferable because solid content is easily precipitated and gelled during polymerization. From this viewpoint, c / d is set to 0.6 or more, and more preferably 0.8 or more. Moreover, when c / d is larger than 3, it is not preferable because the resulting polymer emulsion is inferior in low-foaming property and wettability. From this viewpoint, c / d is more preferably 2 or less.

  In addition, the compound represented by Formula (2) may be used independently, or may use 2 or more types together.

The addition amount of the compound represented by the formula (2) is 20 to 110 parts by weight with respect to 100 parts by weight of the compound represented by the formula (1). When the amount of the compound represented by the formula (2) is lower than 20 parts by weight, the resulting polymer emulsion is inferior in low foaming property and leveling property. From this point of view, the addition amount of the compound represented by formula (2) and 20 parts by weight or more. Moreover, when there are more addition amounts of the compound represented by Formula (2) than 110 weight part, emulsification property will fall and it will become easy to cause precipitation and gelatinization of the solid content at the time of superposition | polymerization. From this viewpoint, the addition amount of the compound represented by the formula (2) is 110 parts by weight or less, and more preferably 100 parts by weight or less.

  The emulsifier composition of the present invention consists of the compound of formula (1) and the compound of formula (2), and the total amount used is usually 0.1 to 20% by weight, preferably based on the monomers described below. Is 1 to 15% by weight.

  The emulsifier of the present invention can be applied to emulsion polymerization of various monomers, and the type of monomer is not particularly limited. Examples thereof include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid. Acid methyl, butyl methacrylate, glycidyl methacrylate, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, acrylamide, methacrylamide, hydroxyethyl ester acrylate, hydroxyethyl ester methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylic acid, Acrylic monomers such as methacrylic acid, aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, divinylbenzene, vinyl acetate, etc. Ester ester monomers, halogenated olefin monomers such as vinyl chloride and vinylidene chloride, conjugated diolefin monomers such as butadiene, isoprene and chloroprene, and others, ethylene, itaconic acid, fumaric acid, maleic acid, methyl maleate, alkyl groups Fluoropolymer monomer having at least one polyfluoro group which is an alkyl group having 1 to 6 carbon atoms in which some or all of the hydrogen atoms are substituted with fluorine atoms and one or more unsaturated groups such as carbon-carbon unsaturated double bonds Etc. These monomers can be used alone or in combination of two or more.

  For emulsion polymerization using the emulsifier of the present invention, conventionally known polymerization initiators can be used without particular limitation. Representative examples include hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, benzyl peroxide, lauryl peroxide, succinyl peroxide, tert-butyl perpivalate, 2,2′- Azobis-2-methylbutyronitrile, 2,2′-azobisisobutyronitrile, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (4 -Methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (2-cyclohexane-1-carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 1,1'- Azobis (1-acetoxy-1-phenylethane), dimethylazobisisobutyrate, 4,4′-azobis (4-cyanovaleric acid) 2,2'-azobis (2-amidinopropane) dihydrochloride, and the like. Redox polymerization can also be performed using sodium hydrogen sulfite, ferrous ammonium sulfate, or the like as a polymerization accelerator. Further, as chain transfer agents, mercaptans such as α-methylstyrene dimer, n-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, carbon tetrachloride, carbon tetrabromide Halogenated hydrocarbons such as may be used.

  Moreover, a solvent can be added in the case of superposition | polymerization. For example, water, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, 2-butanol, tert-butanol, acetone, methyl ethyl ketone, methyl butyl ketone, dimethylformamide, dimethylacetamide, benzene, toluene, xylene, ethyl acetate, etc. Can be mentioned.

  The emulsion polymerization method may be any commonly used method such as a batch polymerization method or a continuous polymerization method. In the case of a batch polymerization method, a solvent, an emulsifier, a monomer and an initiator may be charged all at once, or a monomer and an initiator may be dropped. The polymerization temperature and polymerization time depend on the polymerizability of the monomer and the initiator, but are usually 20 to 130 ° C, preferably 30 to 100 ° C.

  To the polymer emulsion obtained by the above method, stabilizers and thickeners for stabilizing the emulsion and preservatives for preventing spoilage may be added as other components. These may be added before emulsion polymerization or after polymerization. Further, various cationic, anionic, and nonionic surfactants and compounds represented by formula (1) and formula (2) may be added.

  The polymer emulsion obtained using the emulsifier of the present invention is, for example, as a printing ink, paint (for construction, household use, can use, electrodeposition coating, etc.), adhesive, pressure-sensitive adhesive, coating agent, impregnation reinforcing agent, etc. It can be applied to wood, metal, paper, cloth, plastic, glass, ceramic, and other concrete.

Hereinafter, the present invention will be described in more detail with reference to examples.
The synthesis example of the compound represented by Formula (1) concerning this invention is shown. Table 1 shows the synthesized compounds and the compounds used.

(Synthesis Example 1 (Compound 1))
Into a 5 L autoclave, 433 g (3 mol) of 3,5,5-trimethyl-1-hexanol (trade name: Nonanol, manufactured by KH Neochem Co., Ltd.) and 5 g of potassium hydroxide were charged. The temperature rose. Next, 2114 g (48 mol) of ethylene oxide was added dropwise with a dropping device and reacted for 1 hour. Subsequently, 523 g (9 mol) of propylene oxide was dropped with a dropping device and reacted for 2 hours. Thereafter, the reaction product is taken out from the autoclave, neutralized with hydrochloric acid to pH 6-7, and subjected to reduced pressure treatment at 100 ° C. for 1 hour to remove the contained water, and finally the salt is removed by filtration. Thus, 2917 g of a compound represented by 3,5,5-trimethylhexyl-O— (EO) _16- (PO) ₃ —H was obtained.

  Each compound shown in Table 1 was synthesized according to Synthesis Example 1. Table 2 shows the composition, and Table 3 shows the result.

(Preparation of polymer emulsion, emulsion polymerization method, and confirmation of emulsification)
Example 1
In a 300 mL four-necked flask connected with a stirring blade, a nitrogen blowing tube, a thermocouple, and a cooling tube, ion-exchanged water: 90.0 g, 3,5,5-trimethylhexyl-O- (EO) _16- (PO) ₃ represented by -H compound: 2.0 g, 3,5,5-trimethyl-hexyl _{-O- (EO) 4 - (PO} ) 3 represented by -H compounds: charged 2.0 g, uniformly dissolved It was. To this, 2-ethylhexyl acrylate: 40.0 g and potassium persulfate 0.3 g were charged and stirred to uniformly emulsify. While stirring this, the temperature was raised to 40 ° C. in a nitrogen atmosphere and polymerization was carried out for 4 hours to obtain a polymer emulsion.

  In accordance with Example 1 above, emulsion A was prepared by charging Compound A, Compound B, 2-ethylhexyl acrylate, potassium persulfate, and ion-exchanged water in the weights listed in Table 2.

  It means that what is uniformly emulsified at the time of polymerization has excellent emulsifiability, and ○ that obtained a polymer emulsion that was uniformly emulsified, solids precipitated or gelled at the time of polymerization The case where a uniform polymer emulsion was not obtained is indicated by x.

(Foaming test)
Fill the resulting polymer emulsion with 30 mL into a 50 mL screw tube, cap at room temperature, shake up and down 20 times at a rate of 4 times / second, and remove from the liquid level after 1 minute from the end of shaking. The height of the foam was measured. The lower the height of the generated bubbles, the lower the polymer emulsion, and the better it is at 15 mm or less.

(Wettability)
The obtained polymer emulsion was collected in a glass Pasteur pipette, dropped on a polyester film (Toyobo Co., Ltd. Cosmo Shine A4300) and a glass plate (S9224, Matsunami Glass Industrial Co., Ltd.), and dried. The area of the trace was measured. The larger the area after drying, the better the polymer emulsion and the easier it is to apply uniformly, indicating that it is better at 40.0 mm ² or more.

  Examples 1 to 4 using the compounds represented by the formulas (1) and (2) of the present invention were all uniformly emulsified and obtained without precipitation or gelation of solids. The polymer emulsion was excellent in low foaming property and wettability.

Since Comparative Example 1 did not use the compound represented by Formula (1), it gelled during polymerization.
Since the comparative example 2 and the comparative example 3 did not use the compound represented by Formula (2), the obtained polymer emulsion was inferior in wettability.
In Comparative Example 4, since the compound represented by the formula (1) in which the oxypropylene group was not added was used and the compound represented by the formula (2) was not used, the obtained polymer emulsion was wet. It was inferior.

In Comparative Example 5, since the oxypropylene group of the compound represented by the formula (1) was not added, the obtained polymer emulsion was inferior in wettability.
Since Comparative Example 6 did not use the compound represented by Formula (1), it gelled during polymerization.
In Comparative Example 7, since the compound represented by the formula (2) was not used, a solid content was precipitated during the polymerization, and a uniform polymer emulsion could not be obtained.

In Comparative Example 8, the alkyl group of the compound represented by the formula (1) was different and, in addition, the compound represented by the formula (2) was not used, and thus gelled at the time of polymerization.
In Comparative Example 9, since the alkyl group of the compound represented by the formula (1) is different, a solid content was precipitated during the polymerization, and a uniform polymer emulsion was not obtained.

Since the comparative example 10 and the comparative example 11 did not use the compound represented by Formula (1) and Formula (2), the obtained polymer emulsion was inferior to low-foaming property or wettability.
Since Comparative Example 12 did not use the compounds represented by Formula (1) and Formula (2), solid content was precipitated during polymerization, and a uniform polymer emulsion could not be obtained.

Claims (2)

An emulsifier for emulsion polymerization, comprising 20 to 110 parts by weight of a compound represented by formula (2) to 100 parts by weight of a compound represented by formula (1).

_{^{R 1 O- (AO) a -}} (PO) b -H (1)

(In the formula (1), R ¹ is an alkyl group having 9 carbon atoms, AO is an oxyethylene group or an oxypropylene group, a is the sum of the average added moles of AO, and a = 10 to 35 (AO) 70% by weight or more of (AO) _a is occupied by oxyethylene groups, PO is an oxypropylene group, b is the average number of moles of PO added, and b = 3 to 5, / B = 3-12.)

_{^{R 2 O- (EO) c -}} (PO) d -H (2)

(In the formula (2), R ² is an alkyl group having 9 carbon atoms, EO is an oxyethylene group, PO is an oxypropylene group, c is an average added mole number of EO, and c = 2 to 2. 9 and d is the average number of moles of PO added, d = 2-4, and c / d = 0.6-3.) The emulsifier for emulsion polymerization according to claim 1, wherein AO of the compound represented by formula (1) is an oxyethylene group.