JPH11189608A - Reactive emulsifier and production of polymer emulsion by emulsion polymerization using the same as emulsifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an aqueous polymer emulsion which can form a coating film or an adhesive film excellent in water resistance. SOLUTION: There are provided a reactive emulsifier comprising a macromonomer prepared by introducing a radically polymerizable group into one end of a polymer comprising epoxy-containing (meth)acrylate units, ω- alkoxypolyalkylene glycol mono(meth)acrylate units, and, optionally, other vinyl monomer units and a process for producing a polymer emulsion, comprising emulsion-polymerizing a radically polymerizable monomer in the presence of the reactive emulsifier in an aqueous medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reactive emulsifier comprising a macromonomer having a polymer skeleton having a specific functional group and a method for producing a polymer emulsion by emulsion polymerization using the same as an emulsifier. According to the polymer emulsion obtained by the present invention, a coating film or an adhesive film having extremely excellent water resistance can be obtained.

[0002]

2. Description of the Related Art Aqueous polymer emulsions, which take advantage of their non-polluting properties, good workability, and resource savings, are used in paints, adhesives, paper processing agents, fiber processing agents,
It is used for a wide range of applications such as mortar modifiers. Conventionally, aqueous polymer emulsions are most commonly emulsion polymerized using low molecular weight compounds such as sodium alkyl benzene sulfonate, polyoxyethylene alkyl allyl ether sulfate or polyoxyethylene nonyl phenyl ether as an emulsifier. It was manufactured by. However, the aqueous polymer emulsion produced by the above-mentioned method has a problem that the water resistance of a dried and formed film is inferior due to a low molecular weight emulsifier.

As a method for solving the above problems, a method of emulsion-polymerizing an unsaturated monomer in the presence of a polymer emulsifier, or a method having a radically polymerizable unsaturated group and being incorporated as a part of a polymer at the time of emulsion polymerization. There is an emulsion polymerization method using an emulsifier having a characteristic, ie, a reactive emulsifier (for example,
JP-A-5-154369 and JP-A-9-314
No. 4 publication). However, the water resistance of the film formed from the polymer emulsion obtained by the above method,
In each case, it was still a step away. As an example of a reactive emulsifier, polyethylene glycol mono (meth) acrylate was also known, but it was poor in copolymerizability with other unsaturated monomers used as a main component of emulsion polymerization,
The water resistance of the resulting polymer emulsion was still not satisfactory because it was likely to remain unreacted.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous polymer emulsion which can form a coating film or an adhesive film having excellent water resistance.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, according to the emulsion polymerization using a reactive emulsifier comprising a radical polymerizable macromonomer having a specific structure, The present inventors have found that an aqueous polymer emulsion that forms a film having extremely excellent water resistance can be obtained, and have completed the present invention. That is, the present invention provides a (meth) acrylate unit having an epoxy group, ω
A reactive emulsifier comprising a macromonomer obtained by introducing a radical polymerizable group at one end of a polymer comprising an alkoxypolyalkylene glycol mono (meth) acrylate unit and optionally another vinyl monomer unit,
Further, it is a method for producing a polymer emulsion by emulsion polymerization using the reactive emulsifier. Hereinafter, the present invention will be described in more detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the macromonomer in the present invention has a radical polymerizable group at one end of a specific polymer skeleton having an epoxy group or the like.
A macromonomer consisting of a polymer skeleton having an epoxy group is a novel compound, and the present inventors have filed a patent application for the same (Japanese Patent Application No. 8-326003).
issue). A macromonomer having a polymer skeleton having an epoxy group includes a polymer having an epoxy group in a molecular chain and having a hydroxyl group at one end (hereinafter sometimes referred to as a base polymer) and a monomer having an isocyanate group. Can be produced by reacting

The above-mentioned base polymer is obtained by subjecting (meth) acrylate having an epoxy group, ω-alkoxypolyalkylene glycol mono (meth) acrylate and other vinyl monomers to a radical in an organic solvent in the presence of hydroxyalkyl mercaptan. It can be produced by polymerizing. The polymerization temperature is preferably from 50 to 140 ° C,
As the polymerization solvent, ethyl acetate, butyl acetate, methyl isobutyl ketone, toluene, xylene and the like can be preferably used. Examples of the polymerization initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanecarbonitrile, benzoyl peroxide, toluoyl peroxide, butylperoxypivalate, and butylperoxyoctanoate. The preferred amount is 0.1 to 3 parts by weight per 100 parts by weight of the monomer.

Examples of the hydroxyalkyl mercaptan include hydroxyethyl mercaptan, hydroxybutyl mercaptan, hydroxyhexyl mercaptan and the like. The hydroxyalkyl mercaptan acts as a chain transfer agent in the polymerization reaction and binds to one end of the base polymer. Therefore, the preferred amount of the hydroxyalkyl mercaptan used is an amount equimolar to the obtained base polymer, and specifically, the base polymer: hydroxyalkyl mercaptan = 1: (0.8 to 1.3)
(Molar ratio). The number of moles of the obtained base polymer is
It is determined by the weight of the monomer to be subjected to polymerization and the number average molecular weight of the polymer. For example, when trying to obtain a base polymer having a number average molecular weight of 5,000 using 100 g of the monomer, the number of moles of the obtained polymer is 0.02, so that the molecular weight of hydroxyalkyl mercaptan is 78.13.
If hydroxyethyl mercaptan is used, the amount used is preferably 1.56 g (0.02 mol). The preferred number average molecular weight of the base polymer is from 1,000 to 30,000
0.

Examples of the (meth) acrylate having an epoxy group include glycidyl acrylate, glycidyl methacrylate, and 3,4-epoxycyclohexylmethyl methacrylate. The amount of the (meth) acrylate having an epoxy group to be used is preferably such that an average of 2 to 5 epoxy groups can be introduced per one molecule of the base polymer. If the number of epoxy groups in one molecule of the base polymer is less than 2 on average, the proportion of the base polymer containing no epoxy group increases, while if it exceeds 5 on average, the resulting macromonomer is used as a raw material. The weather resistance of the film formed from the polymer emulsion obtained by the above-mentioned method tends to decrease. The preferred ratio of the (meth) acrylate monomer unit having an epoxy group in the base polymer is 1% by weight based on the total amount of all the monomer units constituting the polymer.
５０50% by weight.

The ω-alkoxypolyalkylene glycol mono (meth) acrylate includes methoxy polyethylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, butoxy polypropylene glycol mono (meth) acrylate, benzyloxy polyethylene glycol (meth) acrylate. A) acrylate, methoxypolyethylene glycol polypropylene glycol mono (meth) acrylate and methoxypolytetramethylene glycol polyethylene glycol mono (meth) acrylate.

The number of carbon atoms of the alkyl in the ω-alkoxy group is preferably 7 or less, more preferably methyl and ethyl. When the alkyl group has more than 7 carbon atoms, the hydrophobicity becomes strong, and the emulsifying performance tends to decrease when the alkyl group is formed into a macromonomer. ω-alkoxypolyalkylene glycol mono (meth)
The molecular weight of the acrylate is preferably from 2 to 50, more preferably from 3 to 30, in terms of the degree of polymerization of the alkylene glycol. When the degree of polymerization of the alkylene glycol exceeds 50, the water resistance of the film formed from the obtained polymer emulsion tends to decrease. ω-alkoxypolyalkylene glycol mono (meth)
The number of carbon atoms of the alkylene in the alkylene glycol unit constituting the acrylate is preferably 2 or 3, and particularly preferably 2. A preferred ratio of the ω-alkoxypolyalkylene glycol mono (meth) acrylate unit in the base polymer is:
It is 50 to 99% by weight in terms of% by weight based on the total amount of all the monomer units constituting the polymer. Ω-alkoxypolyalkylene glycol mono (meth) in base polymer
If the proportion of the acrylate unit is less than 50% by weight, the emulsifying power required for emulsion polymerization tends to be insufficient, while if it exceeds 99% by weight, it becomes difficult to use other monomers.

The base polymer can also be produced by copolymerizing (meth) acrylate monomer having an epoxy group and ω-alkoxypolyalkylene glycol mono (meth) acrylate with another vinyl monomer. Examples of other vinyl monomers include (meth) acrylate, vinyl carboxylate, (meth) acrylonitrile, styrene, perfluoroalkylethyl (meth) acrylate, and perfluoroalkyl (meth) acrylate. When the polymer emulsion is required to have adhesion to an inorganic base material or dispersion,
Other vinyl monomers such as dimethylaminoethyl (meth) acrylate, N-alkyl (meth) acrylamide, (meth) acrylamide, or alkoxyethyl (meth) acrylate may be used. A preferable ratio of the vinyl monomer unit in the base polymer is a percentage by weight based on the total amount of all the monomer units constituting the polymer.
And 0 to 40% by weight.

A macromonomer can be produced by reacting a monomer having an isocyanate group with a base polymer having a hydroxyl group at one end obtained by the above method. Examples of the monomer having an isocyanate group (hereinafter referred to as an isocyanate compound) include isocyanate methacrylate, isocyanatoethyl methacrylate, and 3-isopropenyl-α, α-dimethylbenzyl isocyanate. Preferably, 3-isopropenyl-α, α-dimethylbenzyl isocyanate is excellent in stability against moisture. The amount of the isocyanate compound to be used is at least equal to the amount of the hydroxyl group introduced at one terminal of the base polymer, and specifically, preferably 1.0 to 2 times the molar amount of the hydroxyl group. After the reaction,
When a large amount of the isocyanate compound remains, the excess isocyanate may be inactivated with methanol or ethanol.

In order to accelerate the addition reaction between the hydroxyl group and the isocyanate group of the base polymer, dibutyltin dilaurate, dimethyltin dilaurate, tetrabutyldiacetoxystannoxane, lead octoate, lead naphthenate, tertiary amine or quaternary amine It is preferable to add an appropriate amount of a secondary ammonium salt or the like as a catalyst. The reaction is preferably carried out in an organic solvent inert to isocyanate groups, and can be usually carried out in a solution of a base polymer obtained by solution polymerization in an organic solvent. The reaction temperature is preferably from 50 to 140C.

The present invention is a reactive emulsifier comprising a radical polymerizable macromonomer (hereinafter simply referred to as a macromonomer) obtained by the above method, and there is no particular limitation on the use of the reactive emulsifier of the present invention. An example of a preferred use of the reactive emulsifier comprising the macromonomer is an emulsifier for emulsion polymerization for producing an aqueous polymer emulsion. In order to use the macromonomer as an emulsifier for emulsion polymerization, it is necessary to separate the macromonomer from the organic solvent solution, that is, to remove the organic solvent.
The organic solvent may be removed using a thin film evaporator or an evaporator. The organic solvent content of the macromonomer used as an emulsifier for emulsion polymerization is preferably 5% by weight or less.

The invention in which the above macromonomer is used for aqueous emulsion polymerization of an ethylenically unsaturated monomer will be described below. As the ethylenically unsaturated monomer (hereinafter referred to as emulsion polymerization monomer) to be used for polymerization, a monomer or a monomer mixture suitable for aqueous emulsion polymerization can be preferably used. Acid esters, vinyl carboxylate, (meth) acrylonitrile, styrene, perfluoroalkyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, N-alkyl (meth) acrylamide, (meth) acrylic acid, maleic acid, itaconic acid, Maleic anhydride, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphoxyethyl methacrylate, 3-chloro-2 acid phosphoxypropyl methacrylate and the like can be mentioned. Similarly to the above monomers, alkali metal salts, ammonium salts or amine salts of monomers having an acidic group such as a carboxyl group, a sulfo group or a phospho group can also be used.

A more preferred monomer for emulsion polymerization is a monomer mixture containing a monomer having a functional group which reacts with an epoxy group (hereinafter referred to as an epoxy-reactive monomer). The epoxy-reactive monomer is a monomer having an acidic group such as a carboxyl group, a sulfo group or a phospho group, and specifically includes (meth) acrylic acid, maleic acid, itaconic acid, maleic anhydride, and styrene. Sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate and the like can be mentioned. The proportion of the epoxy-reactive monomer used is 0.1 to 10% by weight based on the total amount of all the monomers to be subjected to the aqueous emulsion polymerization.
And more preferably 0.1 to 5% by weight. 0.1% by weight of epoxy reactive monomer used
If it is less than 10%, the stability of the polymer emulsion is low. On the other hand, if it exceeds 10% by weight, the water resistance of the film tends to be poor. In addition,
The total monomers based on the above weight% are the sum of the macromonomer and the monomer for emulsion polymerization. Since most of the epoxy-reactive monomers are hydrophilic monomers, the use of them makes it possible to obtain an aqueous polymer emulsion having excellent dispersion stability. In the present invention, an epoxy-reactive monomer unit in an aqueous polymer emulsion reacts with an epoxy group introduced into the emulsion by the macromonomer during film formation by the emulsion,
As a result of the crosslinking of the polymers, a film having extremely excellent water resistance is obtained.

The preferred amount of the macromonomer used in the emulsion polymerization is from 1 to 30 based on the total amount of all the monomers.
%, More preferably 1 to 20% by weight. If the amount of the macromonomer is less than 1% by weight, the emulsifying power is poor, while if it exceeds 30% by weight, the water resistance of the obtained polymer emulsion is reduced.

The polymerization initiator used in the emulsion polymerization may be any commonly used radical generating compound, such as potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, butylcumyl peroxide, benzoyl peroxide, Toluoyl peroxide and azobisisobutyronitrile. Further, a chain transfer agent such as mercaptoethanol, 2-propanethiol, 1-butanethiol, thiophenol or dodecylmercaptan may be used for adjusting the molecular weight of the obtained polymer. Further, if necessary, other nonionic emulsifiers, anionic emulsifiers and nonionic anionic emulsifiers may be used in appropriate amounts.

In the emulsion polymerization, various known methods can be employed for adding each component to the polymerization vessel. In each case, the polymerization temperature and time are generally temperatures;
~ 90 ° C, time; preferably 1-10 hours. Specifically, there are the following methods. Pre-emulsion method: A macromonomer, a vinyl monomer having a carboxyl group, other vinyl monomers and ion-exchanged water are previously mixed by a homomixer,
A method in which a pre-emulsion is obtained, and the pre-emulsion is supplied to a pot at one time or continuously, and polymerization is carried out while supplying a polymerization initiator at one time or continuously. All-monomer supply method: A part of ion-exchanged water, an emulsifier and a polymerization initiator are charged in a kettle in advance, and all the monomers including the macromonomer are continuously supplied therein while stirring the content liquid. To polymerize. Macromonomer initial charging method: Part of ion-exchanged water,
A method in which a macromonomer and a polymerization initiator are charged into a kettle, and the monomer is supplied therein to perform polymerization.

When an acidic group-containing monomer is used in the emulsion polymerization, it is preferable to neutralize the acidic group in the polymer after termination of the polymerization. A polymer emulsion having an unneutralized acidic group has poor dispersion stability, and tends to block when left unneutralized. As the base for neutralization, diethylamine, dimethylamine, diethanolamine, methylethanolamine, piperidine, triethylamine, dimethylethanolamine, triethanolamine and the like are preferable.

Uses of the aqueous polymer emulsion obtained by the above method include paints, coating agents, adhesives, pressure-sensitive adhesives, impregnating reinforcing agents and the like. As a base material on which this is applied, there are metal, paper, wood, glass, concrete and the like. Examples and Comparative Examples below,
The present invention will be described more specifically. In addition, the part in each example means a weight part.

[0023]

[Production Example 1] (Production of macromonomer A) Toluene 10
A mixture of 0 parts and 1.0 part of 2-mercaptoethanol was heated to 90 ° C. under a nitrogen stream and stirred, and 95 parts of methoxypolyethylene glycol monomethacrylate (average degree of polymerization of ethylene oxide: 9) and glycidyl were added to the liquid. 5 parts of methacrylate and 1 part of azobisisobutyronitrile were added dropwise over 4 hours. By further heating for 2 hours, a toluene solution of an epoxy group-containing polymer having a hydroxyl group at one terminal having a number average molecular weight of 9,100 was obtained. To the resulting solution was added dibutyltin dilaurate 0.1.
One part was added and dehydrated with a molecular sieve, and when the water content in the solution became 200 ppm or less, 3.9-isopropenyl-α, α-dimethylbenzyl isocyanate was added.
A solution obtained by diluting a part (1.5-fold mol of mercaptoethanol) with 10 parts of toluene was added dropwise, and the mixture was heated at 70 ° C. for 3 hours. After that, it was cooled to room temperature, and then ethanol was added.
Five parts were added to deactivate the excess isocyanate. Thereafter, the solvent was removed with a spray dryer to obtain 98 parts of a fine powdery wax-like macromonomer. Its number average molecular weight is 9,500 and its weight average molecular weight is 21,
000.

[0024]

Example 1 First, 20 parts of macromonomer A, 20 parts of butyl methacrylate, 30 parts of styrene, 20 parts of ethyl acrylate, 1 part of methacrylic acid, 9 parts of hydroxyethyl methacrylate, and 30 parts of ion-exchanged water were mixed by a homomixer and premixed. The emulsion was adjusted. In a glass flask equipped with a stirrer, a dropping funnel, a nitrogen gas inlet tube and a thermometer, 70 parts of ion-exchanged water and 0.1% potassium persulfate were added.
After adding 4 parts and 0.7 parts of ammonium carbonate and replacing the gas phase with nitrogen, the solution was kept at 80 ° C., and the pre-emulsion was added dropwise over 2 hours. After the dropwise addition, the temperature was maintained at 80 ° C. for another hour to complete the polymerization. Then, the desired aqueous polymer emulsion was obtained by neutralizing with triethylamine until the pH became 8.

The following physical properties of the obtained polymer emulsion were measured. a. Storage stability test: After the emulsion was stored at 25 ° C. for one week, the appearance was visually evaluated. b. Water resistance test of coating film; apply emulsion to steel plate,
After drying at 25 ° C. for 2 weeks, the test piece was immersed in water for 2 days, and the whitening state was visually observed. c. Grid: Filter and dry with a 200 mesh net and weigh the amount of aggregates. As a result, the results of storage stability test and water resistance test,
All were good, and the grid amount was 0.1 part.

[0026]

Production Example 2 (Production of Comparative Macromonomer B) 90 parts of methoxypolyethylene glycol monomethacrylate (average degree of polymerization of ethylene oxide: 23) and 10 parts of cyclohexyl methacrylate were polymerized to form a polymer skeleton of the macromonomer. Except for the above, a macromonomer (containing no epoxy group) was synthesized in the same manner as in Production Example 1. The number average molecular weight of this macromonomer was 9,200, and the weight average molecular weight was 22,000.

[0027]

Comparative Example 2 Aqueous emulsion polymerization was carried out in the same manner as in Example 1 using a prepolymer comprising the following monomers. That is, a pre-emulsion was prepared by mixing 20 parts of macromonomer B, 20 parts of butyl methacrylate, 20 parts of styrene, 30 parts of ethyl acrylate, 5 parts of methacrylic acid, 5 parts of hydroxyethyl methacrylate, and 30 parts of ion-exchanged water with a homomixer. The physical properties of the obtained aqueous polymer emulsion were measured in the same manner as in Example 1. As a result, the storage stability test; poor, water resistance test;

[0028]

Example 2 Aqueous emulsion polymerization was carried out in the same manner as in Example 1 using a prepolymer comprising the following monomers. That is, 10 parts of macromonomer A, 10 parts of methyl methacrylate, 30 parts of butyl methacrylate, 10 parts of styrene, 32 parts of ethyl acrylate, 5 parts of methacrylic acid, 3 parts of hydroxyethyl methacrylate, and 30 parts of ion-exchanged water were mixed by a homomixer and premixed. The emulsion was adjusted. For the obtained aqueous polymer emulsion, the same physical properties as in Example 1 were measured. As a result, the results of the storage stability test and the water resistance test were all good, and the grid amount was 0.1 part. Was.

[0029]

Comparative Example 3 As a commercially available reactive emulsifier, 10 parts of Eleminol JS-2 (manufactured by Sanyo Chemical Industries, an anionic surfactant having an ethylenically unsaturated bond introduced into an alkyl succinate having a styrene sulfonic acid unit) Was replaced with the macromonomer A in Example 2, and the same operation was performed. The physical properties of the obtained aqueous polymer emulsion were measured in the same manner as in Example 1. As a result, a storage stability test; good, a water resistance test; slightly poor, and the grid amount was 0.1 part.

[0030]

According to the reactive emulsifier comprising a macromonomer of the present invention, an aqueous polymer emulsion having excellent storage stability can be produced, and a film formed from the emulsion has excellent water resistance. The emulsion can be preferably used as a paint, a coating material, an adhesive, a pressure-sensitive adhesive and the like.

Claims (3)

[Claims] 1. A radical polymerizable group at one end of a polymer comprising an epoxy group-containing (meth) acrylate unit, an ω-alkoxypolyalkylene glycol mono (meth) acrylate unit and optionally other vinyl monomer units. A reactive emulsifier consisting of a macromonomer introduced. 2. A method for producing a polymer emulsion, comprising subjecting a radically polymerizable monomer to emulsion polymerization in an aqueous medium in the presence of the reactive emulsifier. 3. A method for producing a polymer emulsion according to claim 2, wherein a radical polymerizable monomer having a functional group reactive with an epoxy group and another radical polymerizable monomer are emulsion-polymerized. .