JPS6328441B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surfactant for emulsion polymerization of unsaturated monomers. More specifically, in the emulsion polymerization of ethylenically unsaturated monomers, conjugated diene unsaturated monomers, or mixtures of these monomers, it is possible to achieve high surface tension, extremely low foaming, and good mechanical stability. The present invention relates to a surfactant for emulsion polymerization that can provide a suitable emulsion. Emulsions, which are so-called emulsions of various polymeric substances, are now widely used as paints, fiber processing agents, adhesives, paper processing agents, and the like. This is because emulsions use water as a solvent, which is advantageous in terms of environmental pollution and safety for the human body compared to so-called solvent-based emulsions. However, in the production of emulsions, anionic surfactants such as alkylbenzene sulfonates, alkyl sulfate ester salts, higher fatty acid salts, polyoxy A nonionic surfactant such as ethylene alkyl phenyl ether, alone or in a mixture, is used at a concentration of 0.1% relative to the raw material monomer.
The amount of emulsions used is 5% by weight, and the emulsions thus produced have high foaming properties and low surface tension, causing various problems in production and use. For example, high foamability brings about disadvantages such as a large charging volume during emulsion production and insufficient observation of the reaction state.
Furthermore, when the emulsion is used for painting, etc., bubbles may cause pinholes. In addition, if the surface tension is low, the adhesive strength tends to be weak when emulsions are used as adhesives, and when used as fiber processing agents, the permeability of emulsions into fibers is too high and the characteristics of the fibers themselves are affected. becomes difficult to take advantage of. Furthermore, it has been pointed out that since the activator is nonvolatile, it remains in the film prepared from the emulsion and causes a decrease in the water resistance, adhesion, tensile strength, heat resistance, weather resistance, etc. of the film. has been done. The present inventors recognized this current situation, and as a result of intensive research based on the idea that these problems could theoretically be solved by eliminating the low molecular weight surfactant in the emulsion, we found that ~
After oligomerizing a tertiary amino group-containing monomer as an essential monomer component using 22 alkyl mercaptan as a chain transfer agent, 3
When used as a surfactant for emulsion polymerization, an oligomer of a specific molecular weight obtained by oxidizing a class amino group to form an amine oxide produces an emulsion with extremely low foaming properties, high surface tension, and excellent polymerization and mechanical stability. found that it can be prepared,
The present invention has been completed. That is, the present invention uses carbon atoms of 6 to 22 as chain transfer agents.
An emulsion consisting of an amine oxide group-containing polymer compound with an average molecular weight of 1,000 to 10,000 obtained by polymerizing or copolymerizing a tertiary amino group-containing monomer as an essential monomer component using an alkyl mercaptan, and then oxidizing the tertiary amino group. A surfactant for polymerization is provided. The alkyl mercaptan having 6 to 22 carbon atoms according to the present invention may be linear or branched, and the raw material for the alkyl group may be a natural one or cracking of low polymerized paraffin of ethylene or propylene. Artificially produced mercaptans may also be used, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, octadecyl mercaptan, hexadecyl mercaptan, and tetradecyl mercaptan. Particularly preferred are octyl mercaptan and dodecyl mercaptan. The amount of alkyl mercaptan used varies depending on the type of tertiary amino group-containing monomer and the molecular weight of the desired product, but is usually 2 to 20 mol %, preferably 5 to 10 mol %, based on the monomer. The tertiary amino group-containing monomer according to the present invention preferably has an acryloyl group, a methacryloyl group, a styryl group, an allyl group, or a methallyl group, such as (meth)allyldimethylamine, dimethylaminoethyl (meth)acrylate, diethylamino Ethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylaminoethyl polyethoxy (meth)
Acrylate, dimethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)
Examples include acrylamide and dimethylaminomethylstyrene. Among these, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, etc. are preferred in terms of ease of acquisition. The oligomer containing the tertiary amino group-containing monomer of the present invention as an essential component preferably contains 30 mol% or more of the tertiary amino group-containing monomer unit, more preferably 50 mol% or more. be. The monomer other than the tertiary amino group-containing monomer may be any copolymerizable monomer, such as a styrene compound,
(meth)acrylic acid (hydroxy)esters,
Examples include fatty acid esters of vinyl alcohol, (meth)acrylamide, and (meth)acrylonitrile. The polymerization (or copolymerization) can be carried out by any method such as solution polymerization or bulk polymerization, but is preferably carried out in a lower alcohol solvent or a lower alcohol-water mixed solvent. Usually the polymerization temperature is 40-100°C, preferably 60-80°C. If necessary, an inert gas such as nitrogen can be introduced into the reaction system to create an oxygen-free atmosphere. The polymerization reaction is conveniently carried out in the presence of known initiators such as peroxides, persulfates or azobis compounds. Examples of the initiator include hydrogen peroxide, azobis-(isobutyronitrile), potassium persulfate, ammonium persulfate, lauroyl peroxide, and t-butyl peroxide. The amount of initiator is from 0.1 to 5 g per mole of monomer. After polymerization, the tertiary amino group is oxidized with an oxidizing agent to form an amine oxide. Examples of the oxidizing agent include hydrogen peroxide, peracetic acid, ammonium persulfate, sodium persulfate, potassium persulfate, and the like. When the reaction is carried out using a lower alcohol solvent, an aqueous solution of the surfactant of the present invention can be obtained by adding an appropriate amount of water and removing the alcohol content by topping after the reaction is completed. Conveniently, the aqueous solution is subjected to emulsion polymerization as a 10-50% strength solution. It is also important that the molecular weight of the amine oxide group-containing polymer compound of the present invention is in the range of 1,000 to 10,000. The molecular weight can be adjusted by adjusting the ratio between the amount of monomer and the amount of alkyl mercaptan. When the molecular weight of the amine oxide group-containing polymer compound is less than 1000, the foaming properties of the emulsion produced increase and the surface tension decreases, while when the molecular weight exceeds 10000, the viscosity of the produced emulsion becomes too high. This is not practical as it may be difficult to handle. The surfactant for emulsion polymerization of the present invention has an amine oxide group in its hydrophilic portion. As a surfactant belonging to this category, JP-A-51-
No. 23530 discloses a product in which a tertiary amino group-containing monomer is simply polymerized and then converted into an amine oxide. However, this one
It is difficult to say that the balance between hydrophilic and hydrophobic groups is sufficient,
The performance as a surfactant for emulsion polymerization cannot be said to be fully satisfactory. However, since the surfactant for emulsion polymerization of the present invention is manufactured using an alkyl mercaptan having 6 to 22 carbon atoms as a chain transfer agent, a hydrophobic group is always present at the end of the molecule, making it hydrophilic. It has an extremely appropriate balance with hydrophobicity, making it an excellent emulsifier in emulsion polymerization. By using the surfactant for emulsion polymerization of the present invention, emulsion polymerization of monomers can be carried out advantageously, and the resulting emulsion also has excellent performance. The emulsion polymerization reaction using the surfactant for emulsion polymerization of the present invention can be carried out by a known method. For example, for 100 parts by weight of monomer, 80 parts by weight of water
~200 parts by weight, 0.5 surfactant for emulsion polymerization of the present invention
~10 parts by weight, an appropriate amount of a polymerization initiator, and if necessary, an inorganic salt, a chain transfer agent, etc. are added, and a polymerization reaction is carried out under a nitrogen atmosphere by setting an appropriate temperature. The monomers used here include aromatic vinyl monomers such as styrene and α-methylstyrene, acrylic acid or methacrylic acid esters such as methyl acrylate, butyl acrylate, and methyl methacrylate, vinyl chloride, and vinylidene chloride. Examples include vinyl halides such as, vinyl esters such as vinyl acetate, and conjugated dienes such as butadiene and isoprene. These monomers may be used alone or as a mixture of two or more. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Note that all parts in the examples are based on weight. <Synthesis of amine oxide oligomer> Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 to 3 By synthesizing tertiary amino group-containing oligomers with the raw material composition shown in Table 1 and oxidizing them with hydrogen peroxide. An amine oxide oligomer was obtained. The molecular weight of the oligomer was determined by gel permeation chromatography using polyethylene glycol as a standard substance.
In addition, for oligomerization, 400 parts of isopropyl alcohol and 0.8 parts of azobisisobutyronitrile are mixed and dissolved in 100 parts of the raw materials, and the mixture is dissolved under a nitrogen gas atmosphere.
This was done by stirring at 75°C for 8 hours. After the completion of the oligomerization reaction, hydrogen peroxide in an amount equivalent to the tertiary amino group was added, and the oxidation reaction was carried out at 65°C for 3 hours. Then, 500 parts of ion-exchanged water was added and the isopropyl alcohol and water were removed by topping. Amine oxide oligomer was obtained as a 20% aqueous solution.

【table】

[Table] <Preparation of emulsion Part 1> Surfactants obtained in Synthesis Examples 1 to 4 and Synthesis Comparative Examples 1 to 3 and commercially available anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and Oxyethylene (n=
4) Using sodium nonyl phenyl ether sulfate as a surfactant for emulsion polymerization, emulsion polymerization was carried out in the following manner to prepare an emulsion. In other words, distilled water is placed in a four-neck separable flask equipped with a reflux condenser, stirrer, dropping funnel, and nitrogen inlet tube.
After adding 140 parts of ammonia water, 1.3 parts of a surfactant for emulsion polymerization, and 1.5 parts of methacrylic acid to adjust the pH of aqueous ammonia to 4 to 4.5, the temperature was raised to 80°C under a nitrogen atmosphere. Drop 1/10 of a mixture of 15 parts of styrene, 50 parts of butyl acrylate, and 35 parts of methyl methacrylate from the dropping funnel,
Next, 10 parts of an aqueous solution containing 0.5 part of ammonium persulfate was added under stirring to initiate a polymerization reaction. Five minutes after the start of the reaction, the remaining monomer mixture was added dropwise over 2 hours, and the mixture was further aged at 80°C for 1 hour to obtain an emulsion. The pH of the emulsion was adjusted to 8.0 with aqueous ammonia, and the surface tension, foaming properties, polymerization stability, mechanical stability, polymerization rate, and particle size of the emulsion were measured. The results are shown in Table-2.

[Table] C: Sodium polyoxyethylene (n=4) nonylphenyl ether sulfate The measurement method for each item in Table 2 is as follows. ●Surface tension: The emulsion was diluted with distilled water to make the resin content 5%, and measured using the Wilhelmy method at 23°C. ●Foaming property: Pour 100ml of the emulsion diluted to a 5% resin content into a 500ml graduated cylinder, and use a stirrer (Japan Serco Co., Ltd. model).
IMT8S15) for 5 minutes, the total volume of the sample including the generated bubbles was measured, and calculated as a magnification of the original sample volume. ●Polymerization stability: The emulsion was passed through a 100-mesh wire mesh, and the amount that did not pass through was calculated as the percentage by weight of the total polymer. ●Mechanical stability: Calculated as the percentage by weight of the total polymer that was generated when 50 g of the emulsion was stirred for 5 minutes at a rotational speed of 1000 rpm under a load of 10 kg/cm ² using a Marlon method stability tester, and the amount that did not pass through the 100 mesh wire mesh was calculated based on the total polymer. did. ●Polymerization rate: Calculated as the weight percent of the emulsion solid content relative to the theoretical solid content. ●Particle size: Measured by simple turbidity method. <Preparation of emulsion Part 2> As a surfactant for emulsion polymerization, the one in Synthesis Example 1 of the present invention and the commercially available sodium polyoxyethylene (n=4) nonyl phenyl ether sulfate (commercial product C) were used. Then, copolymerization reactions of styrene/methyl methacrylate, styrene/ethyl acrylate, and methyl methacrylate/ethyl acrylate were carried out in the same manner as described above to obtain emulsions. The surface tension, foaming properties, etc. of the emulsion were measured using the methods described above. The results are shown in Table-3.

[Table] As is clear from Tables 2 and 3, some synthetic comparative examples and commercially available products are equivalent to or better than the products of the present invention in terms of the mechanical stability or foaming properties of the prepared emulsions. There are some products that show performance above and above, but they are dependent on surface tension, foaming properties, polymerization stability,
It does not necessarily satisfy all requirements for mechanical stability. On the other hand, the product of the present invention can provide an emulsion that satisfies all of these and has desirable physical properties.

Claims (1)

[Scope of Claims] 1. Obtained by polymerizing or copolymerizing a tertiary amino group-containing monomer as an essential monomer component using an alkyl mercaptan having 6 to 22 carbon atoms as a chain transfer agent, and then oxidizing the tertiary amino group. average molecular weight
A surfactant for emulsion polymerization consisting of a polymer compound containing 1,000 to 10,000 amine oxide groups. 2. Claim No. 2, wherein the tertiary amino group-containing monomer is one or more selected from the group consisting of dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and dimethylaminopropyl methacrylamide. The surfactant for emulsion polymerization according to item 1.