JPS6129361B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a synthetic resin emulsion. Conventionally, synthetic resin emulsions have been synthesized using anionic surfactants, cationic surfactants, or nonionic surfactants as emulsifiers, but it is necessary to change the amount and composition ratio of the emulsifier depending on the polymerization monomer, polymerization conditions, etc. It's annoying and
Furthermore, since the emulsifier is mixed into the emulsion as an impurity, the emulsion film has a drawback of poor water resistance, weather resistance, heat resistance, etc. Furthermore, when an acrylic monomer is used as the synthetic resin, the emulsifier alone produces a large amount of aggregates during polymerization, resulting in only an emulsion with poor mechanical stability. The purpose of the present invention is to perform emulsion polymerization in a stable manner without generating aggregates, to provide an emulsion with excellent mechanical stability, pigment compatibility, etc., and to provide a coating film obtained from the emulsion. An object of the present invention is to provide a method for producing a synthetic resin emulsion having excellent water resistance, heat resistance, weather resistance, etc. That is, the gist of the present invention is to emulsion polymerize radically polymerizable monomers by using polybutadiene having a hydrophilic group at the terminal and a maleated isoprene resin obtained by adding a maleic compound to an isoprene resin as an emulsifier. A method for producing a synthetic resin emulsion is provided. The polybutadiene used in the present invention has a hydrophilic group such as a carboxyl group, a hydroxyl group or an amino group at the end of its molecule, and the number of hydrophilic groups in one molecule is preferably equal to or less than the number of ends of the molecule, More preferably it is 2 or less. The above-mentioned polybutadiene preferably has a cis-1,4 structure or a cis-1,2 structure, and is a polymer mainly composed of butadiene,
In addition to a homopolymer of butadiene, it may also be a copolymer with a small amount of a copolymerizable monomer such as acrylonitrile or styrene. Also, if the molecular weight of polybutadiene is too small, the water resistance and alkali resistance of the emulsion film will decrease, and if it is too large, the polymerization stability will deteriorate.
300~30000 is preferable, more preferably 500~
It is 5000. Further, the above-mentioned hydrophilic group may be any group having hydrophilic properties, but is preferably a carboxyl group, an amino group, or a hydroxyl group. The amount of polybutadiene used is not limited in any way, but it is generally preferred to add 5 to 60 parts by weight per 100 parts by weight of the radically polymerizable monomer. Since the polybutadiene used in the present invention has hydrophilic groups at the terminals, compared to emulsifiers in which hydrophilic groups are randomly added to the main chain of the polybutadiene, such as maleated polybutadiene, there are hydrophobic groups between the hydrophilic groups. It is presumed that the chain length of the hydrocarbons representing the hydrocarbon moieties can be more uniformly regulated, and that a synthetic resin emulsion with high emulsifying ability and excellent pigment miscibility and water resistance has been obtained. Further, in the present invention, polybutadiene having a hydrophilic group at the terminal and a maleated isoprene resin obtained by adding a maleic compound to an isoprene resin are used together as emulsifiers. The isoprene resin used in the present invention is a polymer mainly composed of isoprene, and may be a copolymer with a small amount of a copolymerizable monomer such as butadiene or 1,3-pentadiene in addition to an isoprene homopolymer. . If the molecular weight of isoprene resin is too small, the emulsifying ability will be low when a maleic compound is subjected to an addition reaction to form an emulsifier.
Also, if the molecular weight is too large, the viscosity will be high when dissolved in water and only a small amount can be added, so the number average molecular weight is preferably 500 to 150,000, and 1000 to 1000.
100000 is more preferred. Maleic compounds used in the present invention include:
Examples include maleic acid, maleic anhydride, maleic anhydride derivatives such as maleic anhydride monomethyl ester and maleic anhydride diethyl ester, maleimide, and maleic anhydride is preferably used. In the present invention, the above-mentioned isoprene resin and the above-mentioned maleic compound are subjected to an addition reaction to form a maleated isoprene resin, and any known method may be adopted for this synthesis method, for example, stirring the isoprene resin and the maleic compound. Methods such as heating to a high temperature (approximately 200°C) while stirring, or adding isoprene resin and maleic compound to a solvent and heating to a high temperature (approximately 200°C) while stirring may be adopted. Although the reaction can be carried out without a catalyst during this synthesis, it is preferable to add a peroxide catalyst such as penzoyl peroxide. The acid value of the above maleated isoprene resin is not particularly limited, but if it is less than 20, the emulsifying ability will be low and a good emulsion cannot be obtained, and if the acid value is more than 350, the emulsifying ability will be low and The maleated isoprene resin preferably has an acid value of 20 to 350, more preferably 50 to 200, since the water resistance of the film formed from the obtained emulsion is reduced. The amount of maleated isoprene resin to be used is not limited in any way, but it is generally preferred to use 5 to 60 parts by weight per 100 parts by weight of the radically polymerizable monomer. Also, regarding the ratio of the polybutadiene to the maleic isoprene resin, the weight ratio of the polybutadiene to the maleic isoprene resin is 1 or less because as the latter polybutadiene increases, polymerization stability, pigment miscibility, etc. increase. preferable. In the present invention, when emulsion polymerization is carried out using the above-mentioned polybutadiene having a hydrophilic group at the terminal and the above-mentioned maleated isoprene resin together as an emulsifier, methylamine, ethylamine, triethanolamine, ammonia, sodium hydroxide, ammonium carbonate, It is preferably used after being neutralized with hydrochloric acid or acetic acid. In order to dissolve the polybutadiene and maleated isoprene resin well in water, it is preferable to use a solvent capable of dissolving the resin, such as isoprene pyl alcohol, benzyl alcohol, butyl cellosolve, butyl carbitol, etc. alcohols, esters such as butyl cellosolve acetate, butyl acetate, and amines such as triethylamine and triethanolamine. The radically polymerizable monomers used in the present invention are monomers generally used in emulsion polymerization, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Acrylic acid alkyl esters such as methyl methacrylate, methacrylic acid alkyl esters such as butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, styrene, α-methylstyrene, vinyl acetate, vinyltoluene, vinylpyridine, butadiene, isoprene, chloroprene. , acrylonitrile, methacrylonitrile, etc., and these monomers may be used alone or as a mixture of two or more, and the above monomers may further include acrylic acid, methacrylic acid,
Hydrophilic monomers such as itaconic acid, acrylamide, methacrylamide, dimethylaminoethyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate may be used in combination. . In the present invention, any known emulsion polymerization method may be employed except for the use of the maleated isoprene resin described above. For example, emulsion polymerization may be carried out by irradiation with radical-generating radiation such as gamma rays or electron beams or by adding a radical polymerization initiator.
Examples of radical polymerization initiators include peroxides such as benzoyl peroxide, cumene hydroperoxide, and hydrogen peroxide; azo compounds such as azobisisobutyronitrile; persulfate compounds such as ammonium persulfate and potassium persulfate; Examples include redox catalysts such as chlorine compounds, combinations of the persulfate compounds and reducing sulfoxy compounds, and combinations of perchloric acid compounds and reducing sulfoxy compounds. The monomers, polymerization initiators, etc. may be added by any known method such as a batch addition method, a divided addition method, a continuous addition method, a monomer addition method, an emulsion addition method, etc. In addition, methods are used to make the reaction proceed smoothly, such as purging the reaction system with nitrogen, raising the temperature of the reaction system after the reaction is completed to remove residual monomers, and adding special catalysts. Good too. In addition, if necessary, a conventionally known anionic emulsifier,
A cationic emulsifier, a nonionic emulsifier, a water-soluble polymeric emulsifier such as carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, etc. may be used in combination. In the present invention, emulsion polymerization is carried out by using a polybutadiene having a hydrophilic group at the end and a maleated isoprene resin obtained by adding a maleic compound to an isoprene resin as an emulsifier. Since the emulsifying agent contains a hydrophilic group such as a carboxyl group at the terminal, it has a high emulsifying ability.Furthermore, since the above maleated isoprene resin is used in combination, the emulsifying ability of the emulsifying agent used in the present invention is extremely high, and it can be used in emulsion polymerization. It is suitably used as an emulsifier for polymers, and the polymerization is stable without the generation of aggregates, and the resulting emulsion has excellent mechanical stability, storage stability, pigment miscibility, etc.
It has great adhesive strength. Furthermore, since the emulsifier used in the present invention is a polymer and has an unsaturated group in its molecule, it crosslinks with each other as shown in the change in gel fraction (Table 1) described below. The film made from the synthesized emulsion has excellent water resistance, heat resistance, weather resistance, etc. It also has excellent miscibility with other water-soluble resins, and can be used in combination with epoxy resins, phenol resins, urea resins, melamine resins, etc. to modify it, depending on the purpose of use. Furthermore, by adding a desiccant such as cobalt naphthenate or magnesium naphthenate, which are commonly used in paints, the water resistance and oil resistance of the film can be further improved. Therefore, in the production method of the present invention, it is possible to produce an emulsion that can be used in paints, adhesives, resin processing, etc. and exhibits excellent performance. Next, embodiments of the present invention will be described. The method for measuring water resistance etc. is as follows. 1 Average particle size Measured by turbidity method using Sakurada method. 2. Presence or absence of gel formation The emulsion was passed through an 80-mesh wire mesh to examine the formation of gel. 3 Viscosity Measured at 20℃ and 10rpm using a BM type viscometer. 4 Solvent miscibility Add 1 g of butyl cellosolve to 10 g of emulsion, mix, and filter through an 80-mesh wire mesh.
The ratio of the weight of the residue obtained by drying to the weight of the solid content in the previous emulsion is expressed as a percentage. 4 Gel Decomposition The emulsion film was immersed in tetrahydrofuran at 20°C for 24 hours and overdried with a 200 mesh wire mesh, and the ratio of the residue was expressed in weight percent. 5 Water Absorption The emulsion film was immersed in water at 20°C for 3 days, and the weight increase was expressed as a percentage of the original film. 6 Water Whitening Resistance The emulsion film was immersed in water at 20°C for 3 days, the transmittance of light having a wavelength of 700 mμ was measured, and the ratio to the transmittance of the film before immersion was expressed as a percentage. Example 1 The average molecular weight
29000 isoprene resin (manufactured by Tarare, trade name
LIR-30), 40 g of maleic anhydride, and 2 g of dibutyl malonate were supplied, and the system was purged with nitrogen. Next, the temperature was raised to 175° C. with stirring, and the mixture was reacted for 4 hours to obtain a yellow solid maleated isoprene resin composition. The resulting composition had an average molecular weight of 67,000 and an acid value of 95. 32 g of the above composition was placed in a separable flask equipped with a stirrer, a thermometer, a cooling tube, a nitrogen introduction tube, and a dropping funnel, and polybutadiene having a carboxyl group at the end (number average molecular weight 1350, acid value
65), 200 g of water, 9 g of 28% aqueous ammonia, and 30 g of butyl cellosolve were supplied and dissolved by stirring at 50° C. while purging with nitrogen. Next, 160 g of butyl acrylate, cobalt naphthenate industrial grade cazoline solution (metal content 8% by weight) and potassium persulfate 0.2
After supplying 70 g of water in which g was dissolved, the temperature was raised to 70° C. for reaction. The reaction proceeded uniformly and no gel was generated. The resulting emulsion had a pH of 9.0, a viscosity of 90 cps, a solids content of 38.9%, an emulsion particle size of 128 mμ, and a solvent miscibility of 0.79%.
Next, apply the obtained emulsion onto a glass plate.
A sheet having an average thickness of 200μ was obtained by drying at 20°C. The obtained sheet is hard and transparent, and its water absorption rate is
The water whitening resistance was 34.7%, and the water whitening resistance was 52.0%. In addition, the gel fraction of the dried sheet was measured and the first
Shown in the table. Example 2 A synthetic resin emulsion was prepared under the same conditions as in Example 1 except that polybutadiene having a hydroxyl group at the end (number average molecule 1350, acid value 66) was used instead of the polybutadiene having a carboxyl group at the end of Example 1. I got it. Table 1 shows the physical properties of the emulsion obtained and the properties of a sheet obtained by coating the emulsion on a glass plate under the same conditions as in Example 1. 【table】

Claims (1)

[Claims] 1. Emulsion polymerization of radically polymerizable monomers using polybutadiene having a hydrophilic group at the terminal and a maleated isoprene resin obtained by adding a maleic compound to an isoprene resin as an emulsifier. A method for producing a synthetic resin emulsion, characterized by: 2. The method for producing a synthetic resin eardillon according to claim 1, wherein the polybutadiene having a hydrophilic group at its terminal has a number average molecular weight of 300 to 30,000. 3 The number average molecular weight of isoprene resin is 500~
150,000, the method for producing a synthetic resin emulsion according to claim 1. 4. The manufacturing method according to claim 1, wherein the maleic compound is maleic anhydride. 5 The acid value of maleated isoprene resin is 20 to 350
The manufacturing method according to claim 1.