JPS5817827A - Aqueous dispersion solution - Google Patents

Abstract

PURPOSE:To provide an aqueous dispersion which is improved of stability and is formulated to be made applicable as internal additive agents for inorg. powder, sizing agents for paper, etc. by using modified PVA contg. cationic groups as a dispersant. CONSTITUTION:An aqueous dispersion wherein modified PVA contg. a copolymer unit as a cationic group in a molecule expressed by general formulasIor II, III, etc. is used as a dispersant. The modified PVA is obtd. by copolymerizing vinyl ester such as vinyl acetate, tertiary amine such as N-(1,1-dimethyl-3-dimethyl aminopropyl)methacrylic amide or a polymerizable monomer such as pyridine, imidazole or the like and saponifying vinyl ester units. The modified PVA has cationic activity, and emulsifies and disperss hydrophobic materials such as pulp and inorg. materials stably in water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous dispersion, and particularly to an aqueous dispersion in which a hydrophobic low-molecular substance is dispersed in an aqueous medium using modified polyvinyl alcohol containing a cab-one group in the molecule. The aqueous dispersion of the present invention is useful because it has excellent adsorption and adhesion properties to many substances such as pulp, inorganic substances, and synthetic resins. It is thought that the use of alcohol (abbreviated as PVA) and the cationic nature of the dispersion particles play an important role.

Conventionally, it has been known to make an aqueous dispersion of hydrophobic substances such as oils, fats, rosin, etc. using an appropriate emulsifier.
Adhesive performance was not sufficient. The surfaces of many substances, such as pulp and inorganic materials, are often anionically charged, so cationic surfactants are used to improve adsorption and adhesion performance through electrochemical action. Although it is possible to create an aqueous dispersion having the following properties, the aqueous dispersion thus created often has poor stability and is not suitable for practical use from the viewpoint of toxicity.

Thus, the present inventors investigated a method for obtaining a cationic aqueous dispersion of a hydrophobic substance, and found that when modified PVA containing a cationic group in the molecule was used as a dispersant,
We have completed the present invention by discovering that highly stable cationic aqueous dispersions can be obtained and exhibit excellent performance when applied as internal additives for inorganic powders or as sizing agents for paper. Until now, the concept of emulsifying and dispersing hydrophobic substances using modified PVA containing cationic groups in the molecule as a dispersion stabilizer was completely unknown. It is presumed that this is because although several modification methods have been proposed, it has been difficult to industrially produce the modification method K111, so it has been unthinkable to use cationic group-modified Pv for emulsifying and dispersing hydrophobic substances. The present invention will be explained in more detail below.The cationic groups contained in the modified PVA used in the present invention are primary amines,
It means a chemical structural unit that dissociates in an aqueous solution and becomes positively charged, such as secondary amine, tertiary amine, la-class ammonium salt, pyridine, pyridinium, imidazole, imidazolinium, sulfonium, and phosphonium. Conventionally reported methods for producing cation-modified PVA include a method in which vinyl pyridine and vinyl acetate are copolymerized and then converted into a chloride;
- A method of copolymerizing vinyl phthalimide or N-vinyl succinimide with vinyl acetate, saponifying it, and decomposing the iden-do group with an alkali or dihydrogen, aminoacetalizing PVA with an acid catalyst or converting it into an amino acid. A method of benzacetalization, a method of reacting PVAK alkoxydimethylamine, glycidyltrimethylammonium hydrochloride or 3-chloro-2-hydroxypropyltrimethylammonium hydrochloride, a method of adding acrylamide to PVA and then introducing an amino group by Hofmann decomposition. Methods are known.

Cation-modified PVA synthesized by this method can be used to produce the aqueous dispersion of the present invention, but the above-mentioned method for producing cation-modified PVA requires the cationization step itself to be carried out industrially. The problem is that it is difficult to obtain high quality products with high water emulsification performance.

On the other hand, the following general formulas (1), (...), (1
) T.

or modified PVA containing a copolymerized unit represented by (IV)
Not only does it exhibit cationic activity, but it is also possible to industrially introduce a cationic group and obtain a degree of saponification of nine depending on the purpose, both in a stable and easy manner.

(Here, R', R'', R' are hydrogen atoms or lower alkyl groups (which may contain substituents) %X'''' anion, A is the nitrogen atom in B Each means a group that connects to the nitrogen atom of the amide group.) (ζwhere, +t', R8, and R' are hydrogen atoms, lower alkyl groups, or phenyl groups, and 11G is an alkyl group (which may contain substituents). ), X- means an anion, respectively.) l is a hydrogen atom or an alkyl group (which may contain a substituent), X- is an anion, and D is a combination of the nitrogen atom in B and the The modified PVA containing the copolymerized units represented by the above general formulas (1) to (IV) can be produced by combining vinyl esters, especially vinyl acetate, and the following. Formulas (a) to (d) CH2,000CH 也CH2-CH-0-D-B (d)(
Cocote, R' ~ R', R' ~ R10, X"-$At
Be D) The meaning is the same as above. ) are copolymerized in the presence of a radical polymerization initiator, and then the copolymer is treated with an alcohol solution [K] or an alkali or an acid catalyst to dissolve the vinyl in the copolymer □. It is effectively and easily produced by partially or highly saponifying the ester unit to form a vinyl alcohol unit depending on the purpose.

In the monomer represented by the general formula (a), 11 is a hydrogen atom or a lower alkyl group, but a water atom or a methyl group is usually preferred. R3 is also a hydrogen atom 1+
is a lower alkyl group, and ♂ usually represents a hydrogen atom, ♂ represents a hydrogen atom or an alkyl group which may contain a substituent, and i represents an X-a anion. R4, R', R'D For ordinary purposes, methyl groups are preferred, but for special purposes, lower alkyl groups such as ethyl groups and propyl groups, and for the purpose of imparting reactivity, methylol groups or cationic groups are preferred. An alkyl group containing a substituent such as an aminoalkyl group is also used for the purpose of improving the density. As X, a halogen atom such as chlorine, sulfur, or iodine, or CHIosoa or Fi CHsCsH*80m is preferable, and a chlorine atom is particularly preferable from the economical, safety, or physical properties of modified PVA. When it is in the form of a Bit quaternary ammonium salt, the effects of the present invention can be expressed even with primary to tertiary amines, which are preferable for ease of handling in the production of modified PVA. A, which is the group that connects the nitrogen atom in the amino group B and the silicon atom of the and group, can be any group as long as it contains a stable bond, but it is usually a linear or linearly branched aliphatic group. Among the monomers represented by the above general formula (a), those in the form of tertiary amines (examples of 04 monomers include the following: N-(2-dimethylaminoethyl) acryl agudo, N -(2-dimethylaminoethyl)methacrylamide, N-(3-dimethylaminopropyl)acrylamide, N-(3-diethylaminopropyl)acrylamide, N-(3-dimethylaminopropyl)methacrylamide, N-(3-diethylaminopropyl)acrylamide, propyl) methacrylamide.

N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, N-(1,1-dimethyl-3-dimethylamino, propyl)methacrylamide.

N-(1,1-diethyl-3-dimethylaminobutyl)
Acrylamide, N-(1-methyl-1,3-diphenyl-3-diethylaminopropyl)methacrylamide,
N-(3-dimethylaminohexyl)acrylamide,
N-(3-methylethylaminopropyl)methacrylamide, N-methyl-N-(3-dimethylaminopropyl)acrylamide, N-(2,2-dimethyl-3-dimethylaminopropyl)acrylamide, N-(2, 2-
dimethyl-3-dimethylaminopropyl) methacrylamide t N-1,2-dimethyl-3-diethylaminopropyl)crotonic acid anode, N-(3,3-dimethyl-
4-dimethylaminobutyl)acrylamide, N-(3
, 3-dimethyl-4-dimethylaminobutyl)methacrylamide, N-(3,3-dimethyl-4-dimethylaminobutyl)crotonic acid adenate.

Among the monomers represented by the above general formula (A), those in the form of quaternary ammonium can be easily obtained by quaternizing the above-mentioned tertiary amine monomer with the following omniscient quaternizing agent. can be obtained. dialkyl sulfate, e.g. dimethyl sulfate,
Diethyl sulfate, dipropyl sulfate, alkyl esters of arylsulfonic acids, such as methanesulfonic acid, benzenesulfonic acid, toluenesulfone 11 and methyl, ethyl, propyl, butyl esters, halogenated Vencil, 1Fllt HajJ
Hensyl chloride or benzyl bromide, alkyl halide.

Examples are methyl chloride, ethyl A, and methyl dihydride.

Examples include ethyl chloride, ethyl bromide, and ethyl chloride.

The monomers represented by the general formula (A) include the following four types of monomers listed above.

N-(1,1-dimethyl-3-diethylaminopropyl)acrylamidotrimethyl-(3-acrylamido-3,3-dimethylpropylnoammonium chloride N-(3-diethylaminopropyl)methacrylate trimethyl-(3-methacrylaminopropyl) Polymerization rate of ammonium chloride (doglovir) in producing the modified PVA of the present invention.

It is excellent in terms of stability of the amide group and economic efficiency during monomer production.

In addition, as the monomer shown in (b) above, for example, 1
-Vinyl Cdazole, 1-vinyl-2-methylimie/
/-le m, 1-vinyl-2-ethylimitasol,
1-vinyl-2-phenylimitasol, 1-vinyl-
2,4,5-)limethylimidazole, etc. ◇In addition, the monomer represented by the above general formula (c) and the monomer represented by the above general formula (b) may be combined with the quaternizing agent described above. It can be easily obtained by quaternization.

Examples of the monomer represented by the above general formula (2) include dimethylaminoethyl vinyl ether, dimethylaminopropyl vinyl ether, quaternized products thereof, and vinyloxyethylamine.

Furthermore, modified PVA in which the cationic group is a copolymerized unit represented by the following general formula (V) or (■) is also effective for the present invention. (The atom Otahiro lower alkyl group, R14 means an alkyl group, and the X-a anion, respectively.) Until now, incorporating a vinylanne copolymer unit into a PVA molecule has been more difficult than expected and is still an effective method. Although not known, the present inventors have discovered that vinyl esters, especially vinyl acetate and N-vinyl alcohol amides, especially N-vinylacetoamide.

N-vinyl-N-methylacetate or N-vinyl-N-methylformamide or methyl-N-vinylcarpamine), ethyl-N-vinylcarpamine)
, tart-phthyl-N-vinylcal A-me)
,) fk-N-ingrobenylcarpamate, ethyl-
N-isopropenyl carba*-t.

tert -7'thyl-N-isopropenylcarba/-
) with unsaturated carbamate compounds such as radical 1
By copolymerizing in the presence of a polymerization initiator and then hydrolyzing the cellulose copolymer, all of the amide groups in the N-vinylalkylamide units or the carbamate groups in the unsaturated carbanate units are hydrolyzed. It has also been found that modified PVA containing any amount of vinylamine units can be produced in this way.

The amount of cationic groups in the cationic group-modified PvA used for preparing the aqueous dispersion of the present invention, the degree of saponification, or the modified PvA
The degree of polymerization of VA is appropriately selected depending on the purpose and is not particularly limited, but it is important to skillfully combine these three elements in producing a highly stable aqueous dispersion. For many purposes, the amount of cationic groups is from 0.01 to 10 mol, and the degree of polymerization is from 100 to 100 mol.
Selected from a range of 4000. In general, partially saponified products with a moderate degree of saponification are better than completely saponified products, with a degree of saponification of 50 to 9.
Particularly preferred is a saponification degree range of 6 molar.

Although there is no limit to the amount of the above-mentioned nine-cation group-modified PVA used in producing the aqueous dispersion of the present invention, a range of 1 to 100 parts per 100 parts of the hydrophobic substance is generally appropriate. Next, as the hydrophobic low-molecular substance used in the present invention, any substance that is hydrophobic or insoluble in water can be used, such as spindle oil.

Mineral oils such as gear oil, paraffin wax, #1 excited paraffin, synthetic oils such as asphalt, lubricants such as dioctyl sebacate, dibutyl phthalate, dipter digipate, tars such as creonate oil, coal tar, etc.
l11 Turpentine oil, tall oil.

Natural products such as rosin and modified rosin, or their modified products;
Vegetable oils such as soybean oil and mustard oil, ben(n).

Aromatic hydrogen atoms such as toluene and xylene, aliphatic hydrocarbons, halogenated hydrogen atoms, methyl n-aelectroketones,
Ketones such as di-n-propyl keto y, ethers, incyanates such as xylylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, caproic acid.

Higher fatty acids such as liluinling and their anhydrides,
Cetyl ketene dimer, -, alkyl ketene dimers such as stearyl ketene dimer, alkenyl succinic anhydride such as dodecenyl succinic anhydride, hexadecenyl succinic anhydride, N-2uryl carbomoyl chloride, N-cetyl carmoyl chloride, etc. Examples include alkyl carhomoyl 1114 bodies, oleyl alcohol, and cetyl alcohol natonohigher alcohols.

When emulsifying and dispersing these hydrophobic substances, it is best to simply stir and mix them into the aqueous solution containing the above-mentioned cationic group-modified PVA. Pressure kneader 9
Pressure nozzle emulsifier.

Mixing and stirring devices such as a screw extruder, an ultrasonic emulsifier, and a homomixer are optionally employed. If the hydrophobic substance is solid, it is necessary to dissolve it in an organic solvent and then disperse it.
A method is also employed in which the paste is kneaded in the presence of water using a pressure kneader or a colloid mill to form a paste, and then water is added to the mixture and stirred to form an aqueous dispersion.

Furthermore, when producing the aqueous dispersion of the present invention, a nonionic, anionic or cationic surfactant may be used in combination as required. However, if a large amount of surfactant is used, the aqueous dispersion is likely to cause disadvantages such as a decrease in water resistance and a decrease in adhesive strength when used for various purposes, so care must be taken depending on the purpose or use.

The aqueous dispersion of the present invention has a wide range of applications and exhibits excellent characteristics as an additive for inorganic powder for molding, a water repellent, a waterproofing agent, an insulating agent, a film forming agent, an internal additive for paper, a sizing agent, etc. do. In particular, since the aqueous dispersion obtained when rosin is used as a hydrophobic substance has cationic properties, it can be fixed in the pulp during the papermaking process without using sulfuric acid, etc. It has great significance.

The present invention will be explained in more detail with reference to Examples below.

Note that "parts" means parts by weight. Example 1 A copolymer of trimethyl-(3-acrylamido-3,3-dimethylglobyl) ammonium chloride and vinyl acetate was saponified to form cationic groups. as trimethyl-(3
- Contains 2 moles of acrylamide-3,3-dimethylglobyl) ammonium chloride units and has a degree of saponification of vinyl acetate units of 85 moles - Viscosity at 20°C of a 14% aqueous solution (by B!!1 viscometer. Same below) ) is 29.0(
! 500 parts of machine oil was added to 1120 parts of an aqueous solution containing 92 parts of this modified PVA, and mixed and stirred for 10 minutes using a homomixer to obtain a pale yellow emulsified dispersion. I got it. The particles of the dispersion had a perfect spherical shape with a particle size of 0.5 to 1 μm, and the zeta potential was +30.2 inV as measured by a zetameter, indicating cationicity. The viscosity of the dispersion was 30°C and 60 rpm.
It was found to be useful as an additive for ceramic powder slurry, and had good internal lubrication and moldability.

Comparative Example 1 In Example 1, unmodified PVA (saponification degree of 88 moles) was used instead of cationically modified PVA.

An aqueous dispersion of machine oil was obtained in exactly the same manner as in Example 1, except that a 4% aqueous solution with a viscosity of 26 cP at 201°C was used. The particles of this dispersion were true spheres with a particle size of 0.7 to 2 μm. The shape showed an anionic zeta potential of -20.0 mV'. The viscosity of the dispersion was 41 at 30°C and 60 rpm.
30 cP, and when it is used as an additive in ceramic powder slurry at °C, the mixing condition is poor and pores are generated inside during sintering. Machine oil was prepared in the same manner as in Example 1, except that cationic group-modified PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and six types of co-i content J1 was used instead. An aqueous dispersion was prepared W4, and the zeta potential of its constituent particles was measured. The results are shown in Table 1.

Table 1 (Note 1) A copolymer of tert-butyl-N-vinyl carbamate and vinyl acetate is treated with sulfuric acid to decompose the carbamate groups, and then the vinyl acetate units are saponified with backing soda to produce vinylamine. PVA containing units
Toshitomo.

(Note 2) A copolymer of N-vinylacetamide and vinyl acetate was saponified, and the aqueous solution of the saponified product was treated with caustic soda at 100°C to decompose the amide groups and convert them into vinylamine units.

Example 11.

42 parts of the same cation-modified PVA used in Example 1, 420 parts of rosin, and 70 parts of water were charged into a pressurized Niguu and kneaded at 150°C for 30 minutes to form a cream-like homogeneous mixture. After cooling, water was added and further stirred to obtain an aqueous dispersion of rosin having a solid content of 50. This aqueous rosin dispersion has excellent storage stability, and its constituent particles exhibit cationic properties with a zeta potential of a + 31.2 mV. For reference, when paper was made by internally adding this aqueous dispersion to pulp, a base paper with excellent sizing was able to be produced.

Comparative Example 2 In Example 11, the cationic group-modified PVA was replaced with unmodified PVA (saponification 188%).

An aqueous rosin dispersion was obtained in exactly the same manner as in Example 11, except that an aqueous solution of 411 (viscosity at 20° C. of 26 aP) was used. The constituent particles of this dispersion had an anionic zeta potential of -18.7 mV.

Reference Example The aqueous dispersions obtained in Example 11 and Comparative Example 2 were used as paper sizing agents and evaluated.

Nadian Standard Freeness 450d.
After adding and mixing an aqueous dispersion of 0.5 - based on pulp dry weight to a 1s aqueous slurry of pulp (LBKP) with a freeness level of pulp (LBKP), paper was made using a TAPPI standard sheet machine so that the weight was 60. . After pressing at 5 (-) for 3 minutes, drying at 105℃ for 1 minute, and then conditioning at 20℃ for 48 hours at 65mm H6, Steckigt size degree (JI
S P 8122) was measured and mourned. The results are shown in Table 2.

Table 2: While the invention product of Example 11 exhibits a high degree of sizing, Comparative Example 2 has extremely low effectiveness. This is thought to be due to the fact that the aqueous dispersion of this Example has cationic properties and has excellent fixing properties to the pulp, whereas Comparative Example 2 does not substantially fix the pulp.

Implementation number 2 Cation-modified PVA4 same as that used in Example 2
Part G was mixed with 1,000 parts of water and dissolved by heating at 941-95°C for about 1 hour. Then, the mixture was cooled to 75°C, 400 parts of stearyl ketene dimer was added, and the mixture was mixed with a homogenizer to give 1
The mixture was mixed and stirred for 0 minutes to homogenize. Add water to this,
It was diluted so that the stearyl ketene dimer content was 30-. The zeta potential of the particles of the dispersion observed is +2
It exhibits cationic properties of 9.5mV and has excellent device stability, with no layer separation even after being left for one hour.

Comparative Example 3 In Example 12, cationic starch (3-chlora-
Stearyl was prepared in the same manner as in Example 12, except that a cationized starch with a nitrogen content of 0.25'36 was used by reacting 2- and droxyprobil trimethylammonicum chloride with starch in the presence of sodium hydroxide. An aqueous dispersion of ketene dimer was obtained. The zeta potential of the constituent particles of this dispersion was +25.5 mV, indicating cationic properties. It was thus found that the cation-modified PVA of the present invention has superior dispersion stability to cationized starch conventionally used as a dispersant.

Patent applicant RiRashi Co., Ltd. Representative Patent Attorney Hyo Honda

Claims (1)

[Claims] (1) An aqueous dispersion obtained by dispersing a hydrophobic low-molecular substance in an aqueous medium using modified polyvinyl alcohol containing a cationic group in the molecule (2) Modified polyvinyl alcohol containing a cationic group in the molecule The aqueous dispersion according to claim 1, wherein the alcohol is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (1). Atom Matata Hirolower AR
', R'a is a hydrogen atom or an alkyl group (which may contain a substituent), r means an anion, and a group connecting the nitrogen atom in MudB and the nitrogen atom of the adane group, respectively. (-) The aqueous dispersion according to claim 1, wherein the modified polyvinyl alcohol containing a cationic group in the molecule is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (1). liquid. (In this ζ, R', R', R' 14 hydrogen atoms, lower alkyl group or expanded phenyl group, expanded alkyl group (may contain substituents) %X- means anion, respectively◇ ) The aqueous dispersion according to item 1 of the patent application, wherein the modified polyvinyl alcohol containing a cationic group in the molecule is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (W). ♂16 is a hydrogen atom or an alkyl group (Lx-, which may contain a substituent, means an anion, and D means an aliphatic group connected to the nitrogen atom and oxygen atom in B, respectively.) ts> In the molecule The aqueous dispersion according to claim 1, wherein the modified polyvinyl alcohol containing a cationic group is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (V) or (Vl). u (-CH, -C-)-(V) /\ L2RLa (Here, R13, R12, H1s line hydrogen atoms are Kuyo lower alkyl groups, R14 is an alkyl group (including substituents,
) and X- each mean an anion. ) (6) The aqueous dispersion according to claims 1 to 5, wherein the hydrophobic low-molecular substance is rosin or modified rosin.