JPH0212965B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for producing stable cationic emulsions with positively charged particle surfaces. Conventionally, synthetic polymer emulsions obtained by emulsion polymerization of vinyl monomers have been used for various purposes such as paints, adhesives, fiber treatment agents, and household pastes. Emulsion particles are usually negatively charged due to the use of anionic or nonionic compounds as protective colloids. As a result, the performance of the emulsion obtained is limited, and at present it cannot be said that it fully satisfies the wide variety of requirements required in many applications including paints and adhesives. Incidentally, in recent years, a method has been proposed for producing a cationic emulsion by carrying out emulsion polymerization using a cationic surfactant or a cationic polymer compound as an emulsifier or protective colloid. This cationic emulsion has a strong affinity for materials whose surfaces are generally negatively charged, such as various fibers, synthetic resin powders, ores, and can be used in combination with cationic compounds, so it can be used as a fiber treatment agent, adhesive, etc. , it is expected to add new performance to asphalt modifiers, etc. As a result of intensive research into a method for producing a cationic emulsion with positively charged particle surfaces, the present inventors discovered that vinyl-based emulsion in the presence of a nonionic water-soluble polymer compound and an anionic water-soluble polymer compound They discovered that by adding a cationic water-soluble polymer compound to a polymer emulsion obtained by emulsion polymerization of polymers, it is possible to improve the adsorption power for negatively charged substances, and this led to the completion of the present invention. Ivy. That is, the method for producing a cationic emulsion according to the present invention involves emulsion polymerization of a vinyl monomer in the presence of a nonionic water-soluble polymer compound and an anionic water-soluble polymer compound to form a polymer emulsion. During production, after the emulsion polymerization reaction is completed, a cationic water-soluble polymer compound is added at least 1.5 times the weight of the anionic water-soluble polymer compound. In the present invention, "after the emulsion polymerization reaction is completed"
Generally, after the vinyl monomer is emulsion polymerized, the emulsion polymerization reaction is aged, and in the case where such aging is carried out, it means after the completion of the aging. Vinyl monomers used in the method of the present invention include, for example, fatty acid vinyl esters such as vinyl acetate and vinyl propionate; methyl acrylate, ethyl acrylate, butyl acrylate,
Examples include acrylic esters such as 2-ethylhexyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; these can be used alone or as a mixture of two or more. . Furthermore, ethylene, styrene, vinyl chloride, etc. which can be copolymerized with these vinyl monomers can also be used as copolymerization components. The amount of the vinyl monomer to be used is appropriately selected depending on the intended use of the resulting cationic emulsion, but it is preferably used in the range of 20 to 60% by weight based on the final emulsion. As the nonionic water-soluble polymer compound used in the present invention, for example, the degree of saponification is 70 to 100%.
modified starches such as polyvinyl alcohol, dextrin, hydroxyethyl starch or hydroxypropyl starch; hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, etc., and these can be used alone or as a mixture of two or more types. The amount of the nonionic water-soluble polymer compound used is preferably 0.5 to 5% by weight based on the final emulsion. Examples of the anionic water-soluble polymer compound used in the present invention include anion-modified polyvinyl alcohol having a carboxyl group as a substituent (alkali saponified product of copolymer of acrylic acid ester and vinyl acetate, carboxymethylated polyvinyl alcohol) ), gum arabic, carboxymethyl cellulose with a low degree of polymerization and low substitution, hydroxylethyl or hydroxypropyl cellulose, or anionic water-soluble polymer compounds derived from hydroxyethylated or hydroxypropylated starch (e.g. (obtained by the reaction of hydroxyethylcellulose and sodium monochloroacetate), and these can be used alone or as a mixture of two or more. It is important that the anionic water-soluble polymer compound used in the method of the present invention has appropriate anionic properties, and the content of anionic functional groups is 0.1 to 2 mmol, preferably 0.2 to 2 mmol, per 1 g of polymer.
A preferred amount is 1.5 mmol, more preferably 0.3 to 1.0 mmol. In the present invention, a cationic water-soluble polymer compound is added to negatively charged polymer emulsion particles obtained using an anionic water-soluble polymer compound, so that the adsorption of the cationic polymer onto the particles is as uniform as possible. Moreover, it has the advantage of being strong. Therefore, an anionic polymer compound with an anion group content of less than 0.1 mmol has insufficient affinity with the cationic water-soluble polymer compound that will be added later.
The adsorption of the cationic water-soluble polymer compound to the emulsion particles is not sufficient, and the performance as a cationic emulsion is deteriorated, which is not preferable. On the other hand, when using an anionic polymer compound with an anion group content exceeding 2 mmol,
Since the anionic nature is too strong, addition of a cationic polymer compound causes aggregation of the emulsion or significantly reduces the stability of the emulsion, which is not preferable. The amount of anionic water-soluble polymer compound to be used may be changed as appropriate depending on the strength of its anionic property, but it is used in the range of 0.05 to 1.0% by weight, preferably 0.1 to 0.5% by weight based on the vinyl monomer. be done. If the amount of the anionic polymer compound used deviates from this range, it is not preferred for the same reason as mentioned above. Examples of the cationic water-soluble polymer compound used in the method of the present invention include the following. (i) Cation-modified hydroxyethyl cellulose,
Cationically modified starch, cationically modified guar gum, such as hydroxyethyl cellulose, starch and guar gum with glycidyl trialkylammonium chloride or 3-halogeno-
Examples include cationic modified products into which a quaternary ammonium group represented by the following formula is introduced by reaction with 2-hydroxypropyltrialkylammonium chloride. (In the formula, R ₁ , R ₂ and R ₃ are the same or different alkyl groups or substituted alkyl groups having 1 to 4 carbon atoms,
X represents a monovalent anion. ) (ii) A polymer of a cationic acrylic ester, methacrylic ester, substituted acrylamide or substituted methacrylamide, and a copolymer with acrylamide, represented by the following structural formula. [In the formula, R ₄ is a hydrogen atom or a methyl group, R ₅ , R ₆ and R ₇ are the same or different hydrogen atoms, and have a carbon number of 1 to 4
an alkyl group or a substituted alkyl group, Z is an oxygen atom or NH, m is an integer of 1 to 10, and X
is a monovalent anion. ] (iii) Polymers of diallyldimethylammonium chloride and copolymers of this with acrylamide. The above cationic polymer compounds can be used alone or in any mixture. The amount of the cationic polymer compound added depends on the type of anionic polymer used when producing the emulsion, but generally it is
It is necessary to add 1.5 times or more, and the amount is usually 0.1 to 5% by weight, preferably 0.3 to 3% by weight based on the emulsion. If the amount of the cationic polymer compound added is less than 1.5 times the weight of the anionic polymer compound, the stability of the resulting cationic emulsion will decrease, and the addition of the cationic polymer compound will cause aggregation of the emulsion. This is not desirable because it causes Also, the amount of cationic polymer compound added is 0.1% by weight based on the emulsion.
If the amount is less than 5% by weight, the effect will be insufficient, and if it is added in an amount exceeding 5% by weight, the effect will almost reach saturation, which is disadvantageous in terms of thickening of the emulsion and ease of administration. In the present invention, the emulsion polymerization of vinyl monomers carried out in the presence of a nonionic water-soluble polymer compound and an anionic water-soluble polymer compound can also be carried out in the absence of an emulsifier, but if necessary, Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, and ethylene oxide propylene oxide block copolymer, and carboxybetaine, sulfobetaine, carboxyalkylimidazolinium, etc. This can be suitably carried out using an amphoteric surfactant, and further a cationic surfactant such as a long-chain alkyl quaternary ammonium salt. There is no particular limit to the amount of these emulsifiers added, but they are generally used in an amount of 0.05 to 5% by weight based on the vinyl monomer. Polymerization initiators that can be used in emulsion polymerization of vinyl monomers in the present invention include:
Any water-soluble radical initiator that can be used in conventional emulsion polymerization, such as potassium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and azo-bis(isobutyl Amidine hydrochloride), etc. There is no particular restriction on the amount of the polymerization initiator used, but it is generally 0.01 to 4% by weight based on the vinyl monomer. In the present invention, the polymerization reaction conditions for emulsion polymerization of the vinyl monomer can be based on general conditions,
For example, the reaction temperature is 40-100℃, preferably 50-90℃
℃, the PH is 3-9, preferably 4-8. In order to adjust the pH of the reaction solution, a pH buffering agent such as sodium carbonate, sodium bicarbonate, dibasic sodium phosphate, dibasic sodium phosphate, etc. can be used as appropriate. After completion of the emulsion polymerization described above, the emulsion polymerization reaction is generally aged, and if necessary, deodorization is performed according to a conventional method, and other common additives (e.g., plasticizers such as dibutyl phthalate and dibutyl adipate, ethylene Freeze stabilizers such as glycol and propylene glycol, preservatives, antifoaming agents, etc.) can be added. As mentioned above, the feature of the present invention is that an emulsion is produced by adding a cationic polymer compound to an emulsion obtained by emulsion polymerization using an anionic polymer compound. By emulsion polymerization using an anionic polymer compound, a protective colloid layer of anionic polymer is formed on the surface of the resulting emulsion particles, and as a result, the added cationic polymer compound is strongly adsorbed onto the emulsion particles. , and the emulsion particles are efficiently and positively charged. As a result, emulsions produced according to the invention are characterized by a high affinity for negatively charged substances. Therefore, when the emulsion according to the present invention is used as a general household paste, for example, when rinsing laundry, the paste is diluted with a large amount of water, resulting in a very low paste concentration. Even in the case where the clothing is negatively charged, the starch is sufficiently adsorbed onto the clothing, reducing loss of starch and allowing for effective gluing. Moreover, this emulsion can also be used for various purposes such as modification of asphalt emulsion and paint adhesive. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited to the following Examples. Example 1 In a 500 ml five-neck separable flask equipped with a thermometer, stirrer, reflux condenser, nitrogen inlet tube, and quantitative dropping device, 5 g of polyvinyl alcohol (saponification degree 85%, polymerization degree 1400) and anion-modified 0.5 g of polyvinyl alcohol (acrylic acid group content 5 mol%, degree of saponification 98%, degree of polymerization 1800) and 85 g of ion-exchanged water were added and dissolved at 80°C. Add this mixture to 40
Cool to ℃, then add a solution of 0.5 g of polyoxyethylene nonyl phenyl ether (average number of added moles of ethylene oxide 50) and 0.5 g of sodium carbonate dissolved in 10 g of ion-exchanged water, and stir for a while to make a homogeneous solution. After adding 10 g of vinyl acetate monomer and continuing stirring for 20 minutes while introducing nitrogen, heating was started in a 70°C water bath. When the internal temperature reaches 60℃, add 0.2g of potassium persulfate to ion-exchanged water.
An initiator solution dissolved in 10 g was added. Starting 10 minutes after the start of polymerization, 90 g of vinyl acetate monomer was continuously added over a period of 2 hours. After the continuous addition was completed, the mixture was aged at 80°C for 1 hour to complete the polymerization reaction. After cooling to room temperature, cation-modified hydroxyethyl cellulose (nitrogen content 1.8% by weight, number of moles of ethylene oxide added is 1.7 moles per anhydroglucose unit,
2% aqueous solution viscosity (25℃) 25cps) solid content 3g
The dissolved aqueous solution was added, heated to 50°C, and stirred for 30 minutes to obtain a cationic emulsion. The solid content concentration of this emulsion was 41.5% by weight. The solid content concentration of this emulsion is 0.03% by weight.
The particles were diluted with tap water so that the pH was 7.0 after dilution, and the charged state of the particles was measured using an electrophoresis measuring device (manufactured by Hitachi). The particles are positively charged, and their electrophoretic velocity is 4.2 (μ cm/sec V)
It was hot. In addition, regarding the obtained emulsion, JIS-K
-6828-1977, freeze stability and high temperature stability tests were conducted, and it was confirmed that the produced emulsion was stable. Example 2 Emulsion polymerization was carried out in the same manner as in Example 1, and cation-modified hydroxyethyl cellulose (same as in Example 1) was added to the obtained emulsion.
The compatibility with the emulsion, the stability and electrophoresis of the resulting cationic emulsion were measured by varying the amount of the cationic emulsion. The results are shown in Table 1.

[Table] The condition of the rougeon was observed with the naked eye.
From Table 1, when the amount of cation-modified hydroxyethyl cellulose added is small, the stability of the emulsion is affected. It is clear that the situation becomes extremely bad. Example 3 Emulsion polymerization was carried out in the same manner as in Example 1 except that 0.5 g of carboxymethyl starch having a different degree of substitution was used in place of the anion-modified polyvinyl alcohol of Example 1. Cation-modified hydroxyethyl cellulose (Example 1) was added to the resulting emulsion.
An aqueous solution of 3 g (solid content) dissolved in 50 g of ion-exchanged water was added and mixed at 50°C to test the compatibility of the cation-modified hydroxyethyl cellulose with the emulsion. The results are shown in Table 2.

[Gluing test]

Mini mini washing machine (manufactured by Matsushita Electric Industry Co., Ltd.) at 25℃
3 of water and make the emulsion at solid concentration.
Make a sizing solution by adding 0.05% by weight, add 150g of cotton broadcloth (No. 60), and run the washing machine for 3 minutes to apply the sizing. Next, after dehydrating for 10 seconds in a dehydrator (using the dehydrating tank of a Toshiba washing machine), air drying, ironing, and measuring the tension hardness using the cantilever method according to JIS-L-1079-1976 (if the numerical value is The larger the size, the harder it is). [Measurement of adsorption rate] In the above-mentioned gluing test, the absorbance of the waste liquid after gluing was completed was measured at a wavelength of 600 nm. (Using a Hitachi spectrophotometer). Separately, a calibration curve of solid content concentration and absorbance of the dispersion liquid was determined for each emulsion, and the solid content concentration of the waste liquid after completion of pasting was determined and the adsorption rate was calculated.

[Table] From Table 3, a cationic emulsion obtained by adding a cationic polymer compound to an emulsion obtained by emulsion polymerization using an anionic polymer compound (Example 1)
Even when using a large amount of water, 20 times the weight of the cloth, as in the sizing test shown here, it is clear that it sufficiently adsorbs to the cloth and has an excellent sizing effect. Example 4 Emulsion polymerization was carried out in the same manner as in Example 1, except that the amount of anion-modified polyvinyl alcohol was changed, and cation-modified hydroxyethyl cellulose (same as in Example 1) 3 was added to the resulting emulsion.
The compatibility of the cation-modified hydroxyethyl cellulose with the emulsion was tested by adding and mixing at 50°C an aqueous solution prepared by dissolving 50 g of ion-exchanged water. The results are shown in Table 4 together with the results of the sizing test and adsorption rate measurement using cotton broadcloth (No. 60) in the same manner as in Test Example 1.

[Table] From Table 4, if the amount of the anionic polymer compound added is large, the emulsion will aggregate due to the addition of the cationic polymer compound, and if the amount of the anionic polymer compound added is small, the adsorption power to the cloth will not be sufficient. That is clear. Example 5 Polyvinyl alcohol (saponification degree
Add 2 g of hydroxyethyl cellulose (98%, polymerization degree 1800), 3 g of hydroxyethyl cellulose (number of moles of ethylene oxide added per anhydroglucose unit, 2% aqueous solution viscosity (25°C) 30 cps), 0.2 g of gum arabic, and 80 g of ion-exchanged water at 80°C. It was dissolved in This liquid was cooled to 40°C, then a solution of 0.5 g of sodium carbonate dissolved in 10 g of ion-exchanged water was added, and after stirring for a while, 10 g of vinyl acetate monomer was added and stirring was continued for 20 minutes while introducing nitrogen. , heating was started in a 70°C water bath. When the internal temperature reached 60°C, an initiator solution containing 0.3 g of potassium persulfate dissolved in 15 g of ion-exchanged water was added. Starting 10 minutes after the start of polymerization, 90 g of vinyl acetate monomer was continuously added over a period of 2 hours. After this continuous addition was completed, the mixture was aged at 80° C. for 1 hour to complete the polymerization reaction.
After cooling to room temperature, cationically modified guar gum (nitrogen content 2.6% by weight, 1% aqueous solution viscosity 43 cps)
An aqueous solution of 2 g dissolved in 50 g of ion-exchanged water was added, heated to 50° C., and stirred for 30 minutes to obtain a cationic emulsion. The solid content concentration of this emulsion was 41.0% by weight, and the electrophoresis speed was +5.3 (μ・
cm/sec·V), and the test results of freeze recovery properties and high temperature stability were also good.

Claims (1)

[Claims] 1. When producing a polymer emulsion by emulsion polymerizing a vinyl monomer in the presence of a nonionic water-soluble polymer compound and an anionic water-soluble polymer compound, the emulsion polymerization reaction 1. A method for producing a cationic emulsion, which comprises adding a cationic water-soluble polymer compound at least 1.5 times the weight of the anionic water-soluble polymer compound after completion of the process. 2 The degree of saponification of the nonionic water-soluble polymer compound
2. The method according to claim 1, which is at least one compound selected from the group of 70 to 100% polyvinyl alcohol, dextrin, modified starch, hydroxyethyl cellulose, methyl cellulose, and hydroxypropyl cellulose. 3. The anionic water-soluble polymer compound is an anionic polymer derived from modified polyvinyl alcohol having a carboxyl group as a substituent, gum arabic, carboxymethyl cellulose with a low degree of polymerization and low degree of substitution, hydroxyethyl or hydroxypropyl cellulose, or starch. The method according to claim 1 or 2, wherein the method is at least one compound selected from the group of water-soluble polymers. 4 The cationic polymer compound is a cation-modified hydroxyethyl cellulose, a cation-modified starch, a cation-modified guar gum, a polymer of a cationic (meth)acrylic acid ester or amide, or a copolymer with acrylamide, and a polymer of diallyldimethylammonium chloride, or Claim 1, which is at least one compound selected from the group of copolymers with acrylamide;
The method according to paragraph 2 or 3.