JPS5928565B2 - Latex manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a low-viscosity and low-foaming polymer latex by emulsion polymerization of a vinyl type monomer or a conjugated diolefin type monomer.

During emulsion polymerization of vinyl-type monomers and conjugated diolefin-type monomers, these monomers are solubilized in surfactant micelles used as emulsifiers, and polymerization initiator radicals enter the micelles. It is believed that this is when emulsion polymerization begins. Therefore, the solubilization process of these monomers by surfactants greatly influences the polymerization process of the monomers. For example, the rate of polymerization is proportional to surfactant concentration, and the number of latex particles produced is correlated to the number of micelles initially present in the water. In addition, the obtained latex particles must be stabilized by adsorption of surfactants, and must be stable against temperature changes, frictional effects, and the addition of dyes, pigments, fillers, etc. until the next use process. No. For this reason, emulsifier compositions that do not consist of a single surfactant but contain multiple surfactants have been used for emulsion polymerization.

In such an emulsifier, an anionic surfactant such as sodium alkylbenzenesulfonate or sodium lauryl sulfate is usually used as a main agent. but,
When emulsion polymerization is performed using these emulsifiers, the produced latex has foaming properties. For this reason, foaming occurs when latex is used as an emulsion paint or when various additives are added before resin processing, resulting in a decrease in workability and, furthermore, a decrease in the quality of various final products. This will cause problems. In addition, in the emulsion polymerization process, the polymerization is usually stopped when a polymerization rate of about 95 to 100% is reached, and a stripping operation is performed to remove unreacted monomers by steam distillation. This results in lower workability due to foam treatment and prevention of latex loss due to foam. moreover,
In this case, the concentrating operation after the stripping operation will also be hindered by the foaming. For this reason, attempts have been made to use polymeric emulsifiers that have solubilizing power for vinyl monomers and the like and have low foaming properties.

Among these, low polymers are preferred over high molecular ones so that the produced latex does not become highly viscous. As such polymer emulsifiers, anionic oligomers and telomers into which lipophilic groups such as alkyl groups have been introduced have been proposed, such as styrene-maleic acid copolymers, octyl mercaptan, etc. A cotelomer of acrylonitrile and acrylic acid using C. as a chain transfer agent [C. P. ROe. J
．． COllOldandInterfaceSci. ,
37, 93 (1971)], teloma such as acrylic acid having an alkyl sulfone or alkyl sulfoxide end (Japanese Patent Publication Nos. 47-21811, 47-34832, etc.), and naphthalenesulfonic acid-formaldehyde condensates. However, such polymeric emulsifiers have drawbacks such as the chemical structure and degree of polymerization distribution differing from rod to rod, resulting in inconsistent performance, difficulty in controlling HLB, and poor dispersion stability.

The present inventors conducted extensive research to develop a low polymer emulsifier (oligosoap) that overcomes the drawbacks of conventional polymer emulsifiers, and obtained it by polymerizing without using a chain transfer agent or solvent. A water-soluble derivative of an alkyl vinyl ether-maleic acid derivative alternating low polymer (having an average number of repeating units of several tens or less, preferably 10 or less) has excellent solubilizing power and emulsifying power for vinyl monomers, and has low emulsifying power. It has been found that it has foaming properties and low toxicity, and is superior to its monomer as an emulsifier for emulsion polymerization.

As a result of further research on the emulsion polymerization method of vinyl monomers using this emulsifier, we found that by using this emulsifier together with a nonionic surfactant such as a predetermined molar ethylene oxide adduct of nonylphenol, It has been discovered that it is possible to increase the polymerization rate, and to produce a latex with excellent dispersion stability, low viscosity, low foaming, and low toxicity, and stable against fillers such as calcium carbonate.
That is, in the present invention, when emulsion polymerizing a vinyl type monomer or a conjugated diolefin type monomer, as an emulsifier,
General formula [In the formula, R is an alkyl group having 1 to 20 carbon atoms, X and Y represent a hydrogen atom, an alkali metal, an ammonium ion, an amino group, or an alkyl group, and the alkyl vinyl ether component and maleate among the constituent components When at least one of the acid derivative components is bulky, the average number n of repeating units is 3 to 10, and when neither component is bulky, the average number n is 11 or more and several tens or less.

], more preferably this co-low polymer and HLBl7. The present invention provides a method for producing latex using an emulsion polymerization method using an ethylene oxide-added nonionic surfactant having a molecular weight of 0 to 18.5.

In the present invention, the bulky monomer means a p-Tert octyl group or an isobutyl group in the case of an alkyl vinyl ether, and in the case of a maleic acid derivative, a maleic acid derivative other than maleic anhydride, such as diethyl maleate. etc.

Therefore, non-bulky monomers mean alkyl vinyl ethers or maleic acid derivatives other than those mentioned above.

The alkyl vinyl ether-maleic acid derivative alternating co-low polymer used in the method of the present invention is a novel oligosoap with a narrow polymerization degree distribution, which allows the maleic acid derivative and the alkyl vinyl ether to be transferred without using a chain transfer agent. It can be obtained by reacting without a solvent and further saponifying or esterifying the obtained alternating copolymer.

To explain this in more detail, first, a maleic acid derivative and a linear or branched alkyl vinyl ether having 1 to 20 carbon atoms are alternately copolymerized preferably at a molar ratio of about 1:1. At this time, preferably a small amount of a polymerization initiator is added. If a maleic acid derivative and an alkyl vinyl ether are subjected to bulk polymerization with stirring in an inert atmosphere such as nitrogen or carbon dioxide gas or in air without using a solvent or a chain transfer agent, polymerization occurs rapidly and generates heat. Although the temperature is high, a low polymer having a repeating unit number of several dozen or less and an extremely narrow polymerization degree distribution width can be obtained. The low copolymer thus obtained is saponified or esterified with an alkali or alcohol, and then purified by a conventional method to obtain the desired alternating low copolymer. In addition, in the present invention, HLBl7. It is preferable to use an ethylene oxide-added nonionic surfactant having a molecular weight of 0 to 18.5. Examples of such ethylene oxide-added nonionic surfactants include polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, and the like. Among these, H.L.B.
7. O ~ 18,5, in the case of ethylene oxide adduct of nonylphenol, ethylene oxide 30 ~ 60
Corresponds to a molar adduct. Further, the concentration of the alkyl vinyl ether maleic acid derivative (oligosoap) as an emulsifier is usually set in the range of 0.1 to 8% by weight, preferably 0.5 to 5% by weight in the aqueous solution. Further, the amount of the ethylene oxide-added nonionic surfactant is preferably selected from a range of 0.5 to 8% by weight, although it is better to have a larger amount. It is preferable to use the ethylene oxide-added nonionic surfactant in half to twice the amount of the oligosoap. Vinyl monomers to which the method of the present invention is applied include styrene, methacrylic acid,
Preferred are methacrylic ester, acrylic acid, acrylic ester, vinyl chloride, acrylonitrile, ethylene, isobutylene, and the like.

Moreover, butadiene is a preferable example of the conjugated diolefin type monomer. In the method of the present invention,
The polymerization operation is carried out according to a conventional method using a known polymerization initiator.

According to the method of the present invention, the oligosoap with a narrow polymerization degree distribution represented by the above general formula has no variation depending on the production rod, has excellent surface activity, and has no foaming property, so it can be processed by stripping. There is no fear of foaming during the process, and the workability of latex production is greatly improved.

Therefore, the latex obtained by the method of the present invention also has no foaming properties and is suitable for use in the fields of emulsion paints and various resin processing.

Furthermore, this latex has low toxicity, is non-stick, has excellent dispersion stability, mechanical stability, and has excellent stability against the addition of fillers. Next, the present invention will be explained in more detail based on reference examples and examples.

Reference example n-dotecyl vinyl ether 63.77 (0.30 mol), diethyl maleate 51,77 (0.30 mol) and di-tert-butyl peroxide 9.07 (0.1
When 0 mol) is placed in an 11-volume separable three-necked flask and heated to 120°C at normal pressure while stirring in a nitrogen stream, the temperature continues to rise rapidly, reaches a maximum of about 200°C, and then decreases.

During this time, the reaction was completed within 60 minutes. Next, the reaction solution was allowed to cool to room temperature, methanol was added, and the methanol-insoluble portion was separated and dried, and the yield was 37.27.

According to the boiling point increase method, n of this alternating copolymer is 8 on average,
It was a mixture of dimers or more. The oligomer 1 thus obtained was dissolved in ethanol, and 95% of the ester groups of the oligomer 1 were saponified with an aqueous sodium hydroxide solution to obtain a water-soluble surface active substance.

Example 1 95% of the acid groups of the n-dodecyl vinyl ether-diethyl maleate alternating copolymer (average n-8) obtained according to the reference example were placed in a 500 ml four rose Paraflu flask. 150 ml of mixed aqueous solution containing 5.67 ml of oligosoap saponified with NaOH, 2.27 ml of 40 mol ethylene oxide adduct of nonylphenol, and 100 ml of styrene.
m1 and potassium persulfate 0.257, length 5.5
The rotation speed is 250 r. with cTn semicircular stirring blade. p.
r11. Heat to 70℃ while stirring and add 1 liter of nitrogen gas.
Emulsion polymerization was carried out at a flow rate of 50 ml/Mm.

The time required to complete the polymerization was 32 minutes, and the coagulation was 2.67 minutes.
was produced, but the mechanical stability of the produced latex according to the Marlon stability test was 0%. The surface tension of the latex thus obtained is 35 dyne/CrL.
However, there was almost no foaming property. Example 2 Emulsion polymerization was carried out in the same manner as in Example 1 except that 40 moles of ethylene oxide adduct of nonylphenol was not added. The particle size of the latex produced with 0% physical stability was 711λ.

Similar results were obtained when a 40 mole ethylene oxide adduct of decyl vinyl ether-maleic acid alternating copolymer and nonylphenol was used in place of the alternating copolymer and nonylphenol ethylene oxide adduct.

Example 3 Oligosoap 4.0 in which 45% of the acid groups of n-butyl vinyl ether-diethyl maleinoate alternating copolymer (average n-8) prepared according to Reference Example were saponified with NaOH.
When emulsion polymerization was carried out in the same manner as in Example 1 except that 150 WLI of a mixed aqueous solution containing 4.57 mols of ethylene oxide adduct of nonylphenol was used, the time required to complete the polymerization was 56 minutes, and the coagulated product 1 .27 was produced, but the mechanical stability of the produced latex according to the Marlon stability test was 0%, indicating excellent stability.

Further, this latex was not sticky and had almost no foaming property, and the dispersion stability was not impaired even when calcium carbonate was added. The volume average particle diameter of the produced latex particles was 784λ. Comparative Example 150ml of an aqueous solution containing 4.3y of sodium lauryl sulfate as an emulsifier
When emulsion polymerization was carried out in the same manner as in Example 3 except that Example 1 was used, the time required to complete the polymerization was 36 minutes, and although there was no coagulum, the latex foamed significantly.

The particle size of the obtained latex was 720λ. Example 4 In an 11-volume four-piece separable flask, 100% of the acid groups of an alternating copolymer of doditer vinyl ether-diethyl maleate (average N5) prepared according to the reference example was quenched with NaOH. Add 400ml of an aqueous solution containing 4.07ml of converted oligosoap and 0.547ml of potassium persulfate to a length of 5.5? With semicircular stirring blades, the rotation speed is 250 r.
p. n1. The mixture was heated to 70° C. while stirring, and nitrogen gas was introduced at a flow rate of 150 ml.

Then, 300 ml of a mixed monomer of ethyl acrylate and methyl methacrylate (mixing ratio 7:3) was added dropwise using a funnel to perform emulsion polymerization. The monomer dropwise addition was completed over 30 minutes.

There are no coagulums and the mechanical stability of the obtained latex is 5.
It was %.

Claims (1)

[Claims] 1. A vinyl type monomer or a conjugated diolefin type monomer,
For emulsion polymerization, as an emulsifier, the general formula ▲ mathematical formula,
There are chemical formulas, tables, etc.▼ [R in the formula is an alkyl group having 1 to 20 carbon atoms,
X and Y represent a hydrogen atom, an alkali metal, an ammonium ion, an amino group, or an alkyl group, and when at least one of the alkyl vinyl ether component and the maleic acid derivative component in the constituent components is bulky, the average number of repeating units n is 3. ~10, when neither component is bulky, the average n is 11 or more and several tens or less. ] A method for producing latex by an emulsion polymerization method, characterized by using an alternating co-low polymer type surfactant represented by the following.