JPS619402A - Production of emulsion polymer - Google Patents

Abstract

PURPOSE:To produce an emulsion polymer having a relatively high resin content and good mechanical stability by a simple operation, by continuously feeding a pre-emulsion comprising a monomer, water and an emulsifier and feeding an emulsifier separately and intermittently. CONSTITUTION:A pre-emulsion comprising a radical-polymerizable monomer [preferably, a mixture based on at least two (meth)acrylate esters], an emulsifier (nonionic, anionic or amphoteric surfactant or a mixture thereof) and water is continuously fed in the presence of a radical polymerization initiator and emulsion-polymerized. Separately, an emulsifier is intermittently added to the polymerization system at least once. An emulsion polymer having a relatively high resin content and good mechanical stability can be obtained by a simple operation and used in paints, adhesives, textile processing agents, cement admixtures, etc. Since it can be applied as such without the necessity of enhancing its mechanical stability by the addition of a nonionic emulsifier and has a low content of an emulsifier in its final form of application, the properties such as water resistance is improved.

Description

Detailed Description of the Invention (1) Object of the Invention [Field of Industrial Application] The present invention relates to a radically polymerizable monomer, preferably an acrylic ester and/or a methacrylic ester (hereinafter referred to as [(meth)acrylic ester]). This invention relates to a method for producing an emulsion polymer with good mechanical stability, which is obtained by emulsion polymerization of a monomer mixture mainly consisting of It can be used for various purposes such as paper coating agent and fiber processing aid.

[Conventional technology]

When producing an emulsion polymer by emulsion polymerization of a radically polymerizable monomer, conventionally, for example, a part of a pre-emulsion consisting of a radically polymerizable monomer, an emulsifier, and water is added to water containing a polymerization initiator. A method of starting polymerization and continuously adding the remainder of the pre-emulsion and a polymerization initiator (Japanese Patent Application Laid-Open No.
8-208361) was carried out.

[Problem that the invention seeks to solve]

The emulsion polymer obtained in the above conventional technique is as follows.

The mechanical stability is poor, and when the emulsion is passed through a gear pump or reverse roll coater, the emulsion coagulates and often cannot be used as is.

Another method is to add a nonionic emulsifier to the obtained emulsion polymer to stabilize it, but when using a nonionic emulsifier, it is necessary to add a fairly large amount in order to obtain a sufficient effect. Therefore, the viscosity increases, making it unusable (or, because it contains a large amount of emulsifier, physical properties such as water resistance and adhesive performance deteriorate).

(2) Structure of the Invention [Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive studies regarding the above-mentioned problems.

That is, in the present invention, in the presence of a radical polymerization initiator, a pre-emulsion consisting of a radically polymerizable monomer, an emulsifier, and water is continuously supplied to perform emulsion polymerization, and when producing an emulsion polymer, the emulsifier is separately added. This is a method for producing an emulsion polymer, which is characterized in that it is intermittently added to a polymerization system once or twice or more.

The radically polymerizable monomer used in the present invention may be any one that can be radically polymerized, such as acrylic esters (methyl, ethyl, propyl, butyl, and isobutyl acrylate).

tert-butyl, cyclohexyl, 2-ethylhexyl, lauryl, tridecyl, stearyl ester, etc.),
Methacrylic acid esters (methacrylic acid methyl, ethyl, propyl, butyl, isobutyl, isooctyl, tert-butyl, cyclohexyl, 2-ethylhexyl, lauryl, tridecyl, stearyl esters, etc.), acrylonitrile, methacrylateryl, styrene, vinyltoluene, etc. can give. In addition, depending on the purpose and use, acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid (maleic anhydride), maleic acid half ester, etc., and other functional monomers in abundance such as hydroxyalkyl acrylate or methacrylate ( 2-hydroxyethyl, 2-hydroxyprovir,
3-hydroxyprovir), polyalkylene glycol monoacrylate or methacrylate [(polyethylene glycol, polypropylene glycol monoacrylate or methacrylate), N-methylolacrylamide, and etherified products of these with aliphatic alcohols, acrylamide, glycidyl acrylate or Methacrylate, Dia7ton acrylamide, Hydroxydia7ton acrylamide, etc., Vinyl acetate,
Vinyl ethers, vinylpyrrolidone, etc. can also be used. Further, in the present invention, only one type of these monomers may be used, but normally a mixture of two or more types of monomers is used. Among these radically polymerizable monomers, it is preferable to use (meth)acrylic ester as the main component, and it is more preferable to use acrylic ester as the main component.

In the method for producing an emulsion polymer of the present invention, the purpose is achieved by continuously supplying a pre-emulsion consisting of a radically polymerizable monomer, an emulsifier and water, and separately supplying an emulsifier intermittently; The following manufacturing method is suitable.

First, mix and emulsify the monomer, water and emulsifier to make a pre-emulsion, and separate in a reflux condenser.

In a reactor equipped with a thermometer and a stirrer, add 2 of the total amount of water charged.
Add 0 to 80% by weight of initial water, replace the inside of the 2 reactor with nitrogen, and raise the temperature. For example, if the main component is butyl acrylate, the temperature is preferably about 70 to 90°C. Next, a polymerization initiator is added, and then a portion of the pre-emulsion, preferably 10% by weight or less, is added to initiate polymerization.

If the amount of pre-emulsion exceeds 10% by weight, temperature control during polymerization tends to be difficult and viscosity tends to increase. A part of this pre-emulsion and the aqueous polymerization initiator solution may be added in any order, or may be added at the same time. Subsequently, the temperature is maintained and the polymerization is continued while continuously adding the remainder of the pre-emulsion. At this time, some monomers can be directly added instead of the pre-emulsion. When adding this pre-emulsion,
Separately, an emulsifier is added intermittently.

Here, the ratio of the emulsifier added continuously to the emulsifier added intermittently is preferably 1:'o, ot to 1:100, and more preferably 1=10 from i:o, i. preferable. If the amount of emulsifier added intermittently is less than this ratio, the effect of adding the emulsifier will be diminished, and if it is more than this ratio, the total amount of emulsifier added will increase, and the resulting emulsion polymer will be Water resistance and physical property values deteriorate, making it impractical.

The number of times the emulsifier is added intermittently is preferably 1 to 20 times, more preferably 1 to 5 times. If the number of times exceeds 20, it is close to continuous addition.

The effect of intermittent addition tends to be lost.

After the addition of the pre-emulsion is completed, it is best to add an aqueous solution of a polymerization initiator continuously and age it for a while.

In this way, the desired emulsion polymer with good mechanical stability is obtained.

In the method for producing an emulsion polymer of the present invention, a polymerization initiator is not supplied while the pre-emulsion is being added continuously;
It is preferable to feed the pre-emulsion before or in addition to the continuous feeding of the pre-emulsion.

As the emulsifier used in the present invention, one ordinarily used nonionic, anionic, or amphoteric surfactant may be used alone or in combination. The emulsifier used in the pre-emulsion and the emulsifier added during the process may be the same type or different types.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

In addition, in the following, "part" means part by weight, and "%" means weight %. Moreover, all amounts of emulsifier are amounts calculated in terms of pure content. Furthermore, each physical property value was measured by the following method.

(2) Non-volatile content: Weighed after drying at 107°C for 3 hours according to JIS-6833. (Unit: 2%) 2. PH Measured using a glass electrode according to JIS-6833.

3. Adhesive strength Value measured by 180 degree peeling method according to JIS-ZO237. (Unit: g / 25 dragon) 4. Holding force according to JIS-20237 Load: 1 kg, Temperature: 40°C
Measured at 11 hours.

5. Ball tank Measured at an inclination angle of 30 degrees according to JIS-20237.

6. Viscosity Measured at 2.12 rpm with a rotor using a BM type rotational viscometer unless otherwise specified in accordance with JIS-6833.

(Unit: cps) Furthermore, the following abbreviations will be used for each monomer component.

Acrylic acid butyl ester...BA Acrylic acid...AA Acrylic acid-2-ethylhexyl ester...HA Acrylic acid methyl ester...MA Acrylonitrile...AN Styrene...St Dodecyl mercaptan...DM N -Methylol acrylamide...If-MAM methacrylic acid methyl ester...MMA methacrylic acid...
・MAA Example 1 1 (30 parts of A, 40 parts of BA, 30 parts of MA, 5 parts of AA) Sodium polyoxyethylene alkylphenyl ether sulfate (trade name Lehenol WZ, sold by Kao Atlas)
1 part and 32 parts of water were added to prepare a pre-emulsion.

Separately, 30 parts of water was charged into a reactor equipped with a reflux condenser, a temperature needle, and a stirrer.9 After replacing the inside of the reactor with nitrogen, the temperature was raised to 80°C.
0.5 part of ammonium persulfate was added, and then 1% by weight of the pre-emulsion was added to initiate polymerization. Next, the remainder of the pre-emulsion (99% by weight of the total amount)
was continuously added dropwise for 4 hours at a temperature of 80±1°C. Two hours after the start of the dropwise addition, 0.8 part of sodium polyoxyethylene alkyl phenyl ether sulfate was added. After the continuous dropwise addition of the pre-emulsion was completed, 1.0 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80° C. for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 62% and a viscosity of 500%.
cps, PH was 2.0.

This emulsion polymer was neutralized with 25% by weight ammonia water, and an acrylic thickener (trade name: B-
300) and the viscosity at 20,000 cps (BM
The adhesive properties of the thickened product (measured using a mold rotational viscometer, rotor No., 4, 12 rpm) applied to a 50 μm thick polyester film to a thickness of 30 μm (after drying) are as follows:
Adhesive strength was 1000 g/25 l11m, holding force was not deviated, and ball tack was 7. When the same material prepared for measuring adhesive strength was immersed in water, it had good water resistance and no change in appearance was observed after 5 hours.

In addition, when the viscous product was applied to a reverse roll coater, the mechanical stability was good even though no nonionic emulsifier was added during thickening, and the measuring roll did not become dirty even after 2 hours of operation. Ta.

Examples 2 to 7 The same reaction operation as in Example 1 was carried out by changing the composition of the initially charged water and pre-emulsion in Example 1 and the amount of emulsifier added during the process as shown in Table 1. A product was obtained, and the staining of the metering roll of the reverse roll coater, which indicates mechanical stability, was as shown in Table 2.

Table 1 Measuring roll soiling, ○; No soiling occurred even after 2 hours of operation Example 8 70 parts of BA, 30 parts of MA, 3 parts of AA, DMo.

To 1 part, 0.1 part of sodium lauryl sulfate (Hana Airasu Ni, Ni, trade name Koko Maru 2F) and 40 parts of water were added to prepare a pre-emulsion.

Separately, 40 parts of water was charged into a reactor equipped with a reflux condenser, a thermometer, and a stirrer, and the inside of the reactor was replaced with nitrogen, and the temperature was raised to 80°C.
3% by weight of the pre-emulsion was added, and 0.0% ammonium persulfate was added. 5 parts were added to start double polymerization. After 10 minutes, remove the remaining pre-emulsion (9% of the total amount).
7% by weight) was continuously added dropwise for 4 hours at a temperature of 80±1°C. Every hour after the start of the dropwise addition, sodium polyoxyethylene alkyl phenyl ether sulfate was added four times, 2 parts each, for a total of 8 parts. After the continuous dropwise addition of Plenimaresion was completed, 1 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80° C. for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 57% by weight.

Viscosity 700 cps, pH 2.5, Example 1
Example 9: 40 parts of A, 40 parts of BA, 20 parts of MA, 3 parts of AA,
To 1 part of N-MAMo, 2 parts of polyoxyethylene alkylphenyl ether sodium sulfate, 1 part of polyoxyethylene nonylphenyl ether (trade name: Emulgen 910, sold by Kao Atlas), and 40 parts of water were added to make a pre-emulsion. .

Separately, 40 parts of water was charged into a reactor equipped with a reflux condenser, a thermometer, and a stirrer, and the inside of the reactor was replaced with nitrogen, and the temperature was raised to 80°C.
5% by weight of the pre-emulsion and 0.5 part of ammonium persulfate were simultaneously added to initiate double polymerization. 10 minutes after adding the remaining pre-emulsion (95% of the total amount)
% by weight) was continuously added dropwise for 4 hours at a temperature of 80±1''c. Two hours after the start of dropping, 0.04 part of polyoxyethylene nonylphenyl ether, chill was added. Continuous dropping of Plenimaresion was completed. Thereafter, 1 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80°C for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 56.5% by weight.

The viscosity was 900 cps and the PII was 2.3. When the viscosity of Example 1 and If was increased and applied to a roll coater, the measuring roll was slightly stained even after 2 hours of operation, and there was no problem with operation.

Example 10 To 70 parts of HA, 30 parts of MA, 4 parts of AA, 1 part of N-MAMO, and 1 part of DMo, 1 part of sodium polyoxyethylene alkylphenyl ether sulfate and 22 parts of water were added to prepare a pre-emulsion.

Separately, 20 parts of water was charged into a reactor equipped with a reflux condenser, a temperature needle, and a stirrer. After replacing the inside of the reactor with nitrogen, the temperature was raised to 80°C.
1% by weight of the pre-emulsion and 0.5 part of ammonium persulfate were simultaneously added to initiate double polymerization. 10 minutes after adding the remaining pre-emulsion (99% of the total amount)
% by weight) was continuously added dropwise at a temperature of 1° C. for 4 hours. Two hours after the start of dropping, 0.3 part of polyoxyethylene nonylphenyl ether was added. After the continuous dropwise addition of premer resin was completed, 1 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80° C. for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 71.5% by weight.

The viscosity was 900 cps, the pH was 2.3, and the resin content was high and the viscosity was low.

In addition, this emulsion polymer was thickened in the same manner as in Example 1, and an acrylic emulsion type adhesive with a solid content concentration of 50% by weight (trade name: A-2422H, manufactured by Toagosei Chemical Industry Co., Ltd.) was used.
) was applied at a coating speed of 50 m / 1 II in, and when it was dry or coated with a bath roll coater, the distance between the application roll and metering roll was adjusted so that the film thickness was the same as before. When we created a coated product in the same dry state as before, we found that the coating speed was 70 m/mi with the same drying capacity.
I was able to raise it to n.

In addition, the mechanical stability was good, and no staining of the measuring roll occurred even after 2 hours of operation.

Example 11 40 parts of HA, 40 parts of BA, 20 parts of S, t, 5 parts of AA,
A pre-emulsion was prepared by adding 0.05 parts of sodium lauryl sulfate and 40 parts of water.

Separately, 40 parts of water was charged into a reactor equipped with a reflux condenser, a temperature needle, and a stirrer, and after purging the inside of the reactor with nitrogen, the temperature was raised to 80°C.
0.5 part of ammonium persulfate was added, and then 1% by weight of the pre-emulsion was added to initiate polymerization. 10 minutes after the addition, 80 parts of the remainder of the pre-emulsion (99% by weight of the total amount) was continuously added dropwise at a temperature of 1° C. for 4 hours. 24 times every 10 minutes after the start of dropping, add 0 each of sodium polyoxyethylene alkyl phenyl ether sulfate.
．． 25 parts 2 total 6 parts were added. After the continuous dropwise addition of the pre-emulsion, 1 part of a 10% by weight ammonium persulfate aqueous solution was added and the reaction was further maintained at 80"C for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 56.5% by weight, a viscosity of 350 cps, and a pH of 2.2.

This emulsion polymer was thickened in the same manner as in Example 1.
After drying to 0μm thick polyester film to 30μm thick)
The physical properties of the adhesive applied to the adhesive are 400 g/2
5 mm, holding force dropped after 5 minutes, ball tack 8, and when the same item prepared for measuring adhesive strength was immersed in water, it showed relatively good water resistance for 10 hours.

Comparative Example I 30 parts of HA, 30 parts of BA, 40 parts of MA, 3 parts of AA, N-
A pre-emulsion was prepared by adding 1 part of sodium polyoxyethylene alkylphenyl ether sulfate and 40 parts of water to 2 parts of MAMo.

Separately, in a reactor equipped with a reflux condenser, a thermometer, and a stirrer,
After charging 40 parts of water and purging the inside of the 9 reactor with nitrogen,
The temperature was raised to 0.degree. C., 0.5 parts of ammonium persulfate was added, and then 3% by weight of the pre-emulsion was added to initiate polymerization. After one portion of the addition, 80 parts of the remainder of the pre-emulsion (97% by weight of the total amount) was continuously added dropwise at a temperature of 1° C. for 4 hours. After continuous dropping of pre-emulsion, 10
Add 1 part of ammonium persulfate aqueous solution of 2% by weight, and
The reaction was completed by keeping the temperature at 80°C.

The obtained emulsion polymer had a nonvolatile content of 57.3% by weight.

The viscosity was 300 cps and the PII was 2.3. When the viscosity was increased in the same manner as in Example 1 and applied to a roll coater, due to poor mechanical stability, dirt appeared on the metering roll after 1 minute, and operation stopped after 5 minutes. It became impossible.

Comparative Example 2 1-I A pre-emulsion was prepared by adding 3 parts of sodium polyoxyethylene alkylphenyl ether sulfate and 40 parts of water to 70 parts of 1-I A, 30 parts of 5t, and 5 parts of AA.

Separately, 40 parts of water was charged into a reactor equipped with a reflux condenser, a thermometer, and a stirrer, and the inside of the reactor was replaced with nitrogen.
0.5 part of ammonium persulfate was added, and then 1% by weight of the pre-emulsion was added to initiate polymerization. 10 minutes after adding the remaining Lapre emulsion on the left (all i
80 parts of tt7) 9' 9 weight Et%) were continuously added dropwise at a temperature of 1° C. for 4 hours. Two hours after the start of dropping, 0.02 part of sodium lauryl sulfate was added. After the continuous dropwise addition of Plenimaresion was completed, 1 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80°C for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 57.3% by weight.

The viscosity was 300 cps and the PII was 2.3. When the viscosity was increased in the same manner as in Example 1 and applied to a roll coater, due to poor mechanical stability, stains appeared on the metering roll after 2 minutes, and after 15 minutes. I was unable to drive.

Comparative Example 3 BA80 parts, 5t20 parts, AA2 parts, N-MAM0.2
3 parts of sodium polyoxyethylene alkyl phenyl ether sulfate and 40 parts of water were added to the mixture to prepare a pre-emulsion.

Separately, 40 parts of water was charged into a reactor equipped with a reflux condenser, a thermometer, and a stirrer, and the inside of the reactor was replaced with nitrogen at 80°C.
0.5 part of ammonium persulfate was added, and then 3% by weight of the pre-emulsion was added to initiate polymerization. 10 minutes after the addition, 80 parts of the remainder of the pre-emulsion (97% by weight of the total amount) was continuously added dropwise at a temperature of 1° C. for 4 hours. After the continuous dropwise addition of the pre-emulsion was completed, 1 part of a 10% by weight ammonium persulfate aqueous solution was added, and the reaction was further maintained at 80°C for 2 hours to complete the reaction.

The obtained emulsion polymer had a nonvolatile content of 57.3% by weight.

The viscosity was 300 cps and the pH was 2.3. This emulsion polymer was neutralized with 25% by weight aqueous ammonia, and 5 parts of polyoxyethylene nonylphenyl ether was added to increase the mechanical stability. B-300), the viscosity is 20.0
OOcps (B M type rotational viscosity needle, rotor No.
4. Measured at 12 rpm).

50 μm [30 μm W applied to polyester film (after drying), adhesive properties are as follows: adhesive strength 550 g/
25mm, holding force falls in 8 minutes, ball tack is 7,
The same material prepared for measuring adhesive strength was immersed in water and peeled off after 3 hours due to poor water resistance.

(3) Effects of the Invention According to the present invention, an emulsion polymer having a relatively high resin content with particularly good mechanical stability can be obtained by a simple operation, and is industrially useful.

In addition, the emulsion polymer obtained by the present invention has a relatively low viscosity (and is free from stains on the measuring roll when applied to a roll coater, 1) changes in viscosity when strongly stirred, and no formation of coagulates. It also has excellent mechanical stability, which is indicated by the presence or absence of gel, and storage stability, which is indicated by changes in viscosity and the presence or absence of gel when stored at a relatively high temperature for a long period of time.

The emulsion polymer obtained by the present invention can also be used as a paint.

Can be used for adhesives, adhesives, paper coating agents, fiber processing agents, cement admixtures, etc.

Compared to conventional products, it can be coated as is without adding a nonionic emulsifier to increase mechanical stability, and because the amount of emulsifier contained in the final use form is small, physical properties such as water resistance are good. be.

Claims (1)

[Claims] 1. In the presence of a radical polymerization initiator, a pre-emulsion consisting of a radically polymerizable monomer, an emulsifier and water is continuously supplied to perform emulsion polymerization, and when producing an emulsion polymer, the emulsifier is separately added once. Or a method for producing an emulsion polymer, which is characterized in that it is added to the polymerization system intermittently two or more times.