JPH0586402B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polymer obtained by emulsion polymerizing a monomer mixture mainly consisting of radically polymerizable monomers, preferably acrylic esters and/or methacrylic esters (hereinafter collectively referred to as "(meth)acrylic esters"). The present invention relates to an emulsion polymer composition with a high resin content, and more particularly, to an emulsion polymer composition with a high resin content, low viscosity, and stability. In recent years, there has been a strong movement toward synthesizing emulsion polymers with high non-volatile content, as it has been pointed out that they have advantages such as lowering production costs, transportation costs, and storage costs per non-volatile content, and increasing drying speed. . Conventional examples of emulsion polymers with high non-volatile content include:
For example, vinylidene-based polymers as shown in Example 1 of JP-A-56-122874, which are produced by a conventional one-stage emulsion polymerization method, are known. However, it is generally difficult to obtain emulsion polymers with a high non-volatile content by increasing the resin concentration, and even polymers mainly composed of (meth)acrylic acid esters have a high resin content, low viscosity, and are stable. However, it was insufficient to obtain an emulsion polymer with a high temperature. Therefore, in order to obtain a high non-volatile content, it has been necessary to add inorganic fillers such as calcium carbonate, organic fillers such as liquid paraffin and chlorinated paraffin, or use special chemicals.
However, in the case of adding an inorganic filler, the number of steps increases due to the addition of the filler, it is difficult to disperse the filler uniformly, water resistance decreases depending on the type of filler, and adhesive performance decreases in the case of adhesives. There are various problems with paints, such as a decrease in gloss. Further, even when an organic filler is used, various problems such as the above-mentioned performance deterioration and the organic filler oozing out during use, so-called oil leakage, occur. The present inventors have conducted extensive research on emulsion polymer compositions that can be obtained mainly from (meth)acrylic acid esters, which have a high resin content, low viscosity, and are stable without requiring the combination of fillers or special chemicals. As a result, the inventors discovered that a composition obtained by a special two-stage polymerization method was suitable for the purpose, and based on this knowledge, they completed the present invention. That is, the present invention uses 0.001 to 0.01 parts by weight of the emulsifier per 100 parts by weight of the radically polymerizable monomer,
Further emulsion polymerization of the radical polymerizable monomer in a polymer emulsion consisting of polymer particles with an average particle size of 0.3 to 0.5 μm obtained by emulsion polymerization of the radical polymerizable monomer in an aqueous medium. A method for producing a highly concentrated aqueous emulsion with a resin concentration of 60% by weight or more, characterized by: The radically polymerizable monomers used in the first stage emulsion polymerization to obtain the aqueous emulsion in the present invention include acrylic esters (methyl, ethyl, propyl, butyl, isobutyl, tertiarybutyl, cyclohexyl, 2-ethylhexyl,
acrylic esters such as lauryl, tridecyl, and stearyl), methacrylic esters (methyl,
Mainly usable are methacrylic acid esters such as ethyl, propyl, butyl, isobutyl, tertiary butyl, cyclohexyl, 2-ethylhexyl, lauryl, tridecyl, and stearyl), acrylonitrile, methacrylonitrile, styrene, vinyltoluene, and the like. Also a small amount of functional monomer,
For example, acrylic acid, methacrylic acid, itaconic acid, maleic acid (maleic anhydride), maleic acid half ester, acrylamide, glycidyl acrylate, glycidyl methacrylate, N-methylolacrylamide, etc. can also be used. Further, in the present invention, one kind or a mixture of two or more kinds of these monomers may be used. As the radically polymerizable monomer, 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 addition, as the radically polymerizable monomer used in the second stage, acrylic esters (methyl, ethyl, propyl, butyl, isobutyl, tertiary butyl, cyclohexyl, 2-ethylhexyl,
acrylic esters such as lauryl, tridecyl, and stearyl), methacrylic esters (methyl,
Mainly usable are methacrylic acid esters such as ethyl, propyl, butyl, isobutyl, tertiary butyl, cyclohexyl, 2-ethylhexyl, lauryl, tridecyl, and stearyl), acrylonitrile, methacrylonitrile, styrene, vinyltoluene, and the like. 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 small amounts of other functional monomers such as hydroxyalkyl acrylates or methacrylates (2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl), polyalkylene glycol monoacrylates or methacrylates (polyethylene glycol, polypropylene glycol), etc. monoacrylate or methacrylate), N-methylol acrylamide, and etherified products thereof with aliphatic alcohols, acrylamide, glycidyl acrylate or methacrylate,
In addition to diacetone acrylamide and hydroxy diacetone acrylamide, vinyl acetate, vinyl ethers, vinyl pyrrolidone, etc. can also be used. In the present invention, only one of these monomers may be used, but a mixture of two or more monomers is usually used. In the present invention, an emulsifier is used in an amount of 0.001 to 0.01 parts by weight per 100 parts by weight of the radical polymer,
It is necessary to emulsion polymerize the monomer in an aqueous medium to obtain a polymer emulsion consisting of polymer particles having an average particle size of 0.3 to 0.5 μm. If the amount of emulsifier is less than 0.001 parts by weight, emulsion polymerization will be difficult, whereas if it exceeds 0.01 parts by weight, it will be difficult to carry out emulsion polymerization in the second stage emulsion polymerization using the polymer emulsion obtained in the first stage emulsion polymerization as the polymerization medium. , aqueous emulsion with high concentration and low viscosity cannot be obtained. Similar to the first stage emulsion polymerization, the radically polymerizable monomer in the second stage emulsion polymerization is mainly composed of (meth)acrylic acid esters, from the viewpoint of mechanical stability and low viscosity of the resulting emulsion polymer. It is preferable to use it as a main component, and it is more preferable to use an acrylic ester as a main component. In the first stage emulsion polymerization in the present invention,
As emulsifiers, nonionic, anionic or amphoteric surfactants commonly used in emulsion polymerization can be used alone or in combination, and as polymerization initiators, persulfates such as ammonium persulfate, potassium persulfate or Water-soluble radical initiators such as water-soluble oxides can be used. Regarding the method of charging monomers and other polymerization operations, it is preferable to use the methods described below. Mix and emulsify using monomer, water and emulsifier,
Make a pre-emulsion and place 5-50% of the total charge in a separate reactor equipped with a reflux condenser, thermometer, and stirrer.
Add initial water, preferably 10-30% by weight;
The inside of the reactor is replaced with nitrogen and the temperature is raised. For example, if the main component is butyl acrylate, the temperature is preferably about 70 to 90°C. Next, a portion of the pre-emulsion, for example several percent, and an aqueous polymerization initiator solution are added to initiate polymerization. Subsequently, polymerization is continued while maintaining the temperature and continuously adding the remainder of the pre-emulsion and an aqueous polymerization initiator solution. At this time, some monomers can be directly added instead of the pre-emulsion. After the addition of the pre-emulsion is completed, it is preferable to further add an aqueous polymerization initiator solution and age the mixture for a while, thereby obtaining the first stage emulsion polymer. It is necessary that the average particle size (hereinafter simply referred to as "particle size") of the emulsion polymer obtained here is 0.3 to 0.5 μm. If the particle size is less than 0.3 μm, the viscosity will increase when the concentration is increased in the next second stage polymerization, and the desired aqueous emulsion with low viscosity and high resin content cannot be obtained. Anything exceeding this limit is difficult to manufacture. The particle size in the present invention is obtained by measurement using a simple turbidity method (Soichi Muroi, "Chemistry of Polymer Latex", Kobunshi Kankakai (1970), p. 116, etc.) according to the following method and conditions. Refers to the particle size in terms of polymethyl methacrylate. Specifically, approximately 1 g of a sample of the present emulsion is placed in a 100 ml weighing flask using an analytical balance. Immediately after weighing, add 30 ml of distilled water and add additional water to bring the total volume to 100 ml. Transfer 1 to 5 ml of the diluted sample using a pipette to another 100 ml measuring flask, and add distilled water to make 100 ml. Mix the contents of the second flask thoroughly and place a portion in a 1 cm (±0.01 cm) silica cell. The cell is mounted on a Beckman DU™ spectrophotometer and the optical density is measured using a 1.5 mm slit width at a wavelength of 610 millimicrons. The above operation is performed three or more times to obtain three or more sets of different values of nonvolatile content concentration and optical density. The relationship between the nonvolatile content concentration and the optical density obtained here is approximated to a linear equation using the least squares method, and the optical density at a nonvolatile content concentration of 0.03% is calculated. The following relationship exists between the optical density D and the particle diameter d: 〓D=〓d+c. Here c is a constant. Using a methyl methacrylate polymer whose particle size is known in advance, a calibration curve of 〓D−〓d is created. Here, the previously determined optical density D of the sample is applied to the calibration curve, and the particle size (in terms of methyl methacrylate polymer) derived from the calibration curve is regarded as the particle size of this sample. Next, in the second stage of polymerization, the emulsion polymer obtained in the first stage, the aforementioned radically polymerizable monomer, an emulsifier, and a polymerization initiator are used to carry out emulsion polymerization in a conventional manner to obtain the desired emulsion. Obtain a polymer. The aqueous emulsion in the present invention is preferably produced by the following method. First, a pre-emulsion is made using monomer water and an emulsifier. At this time, the ratio of monomer to water is determined depending on the concentration of the target emulsion polymer. Also, as the emulsifier, anionic emulsifiers are preferred. The emulsion polymer obtained in the first stage or its diluted product with water is used instead of the initial water in the same reactor as in the first stage reaction. Emulsion polymer obtained in this first stage/
The water ratio (weight ratio) is preferably 60/40 or more,
More preferably 70/30 to 90/10. This amount is preferably 5 to 50% by weight, more preferably 10 to 30% by weight of the total amount charged. Next, the inside of the reactor is purged with nitrogen and the temperature is raised. (For example, if the main component is butyl acrylate, the temperature is preferably about 70 DEG to 90 DEG C.) Next, a portion of the pre-emulsion, such as several percent, and a polymerization initiator are added to initiate polymerization. The subsequent operations are similar to the first stage polymerization. The particle size of the emulsion polymer produced in the second stage polymerization is
It is about 0.4 μm. The aqueous emulsion obtained by the present invention has a resin content of
60% by weight or more, the viscosity is relatively low, and the mechanical stability is shown by changes in viscosity when vigorously stirred, the presence or absence of precipitates, and the viscosity when stored in a relatively high temperature place for a long period of time. It also has excellent storage stability, as indicated by the presence or absence of changes and gel formation. Furthermore, the aqueous emulsion obtained by the present invention can be used for applications such as paints, adhesives, pressure-sensitive adhesives, paper coating agents, fiber processing agents, cement admixtures, etc., and the manufacturing cost, transportation cost, and storage cost of these products are lower than in the past. Costs etc. can be reduced significantly. Furthermore, when applying the aqueous emulsion obtained by the present invention or the above-mentioned products using the same, the drying speed can be increased due to the high nonvolatile content. In addition, since an aqueous emulsion with a high non-volatile content can be obtained without adding inorganic or organic fillers, the addition of these can reduce the adhesive performance of adhesives, reduce the gloss of paints, and reduce the amount of organic fillers. Problems such as oil leakage do not occur. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the following, parts refer to parts by weight, and % refers to parts by weight.
% means weight %. Moreover, all amounts of emulsifier are amounts calculated in terms of pure content. Furthermore, the measurement of each physical property value was performed by the following method. 1 Non-volatile content Weighed after drying at 107℃ for 3 hours according to JIS-K6833. (Unit: %) 2 PH Measured using a glass electrode according to JIS-K6833. 3 Adhesive strength Value measured by 180 degree peeling method according to JIS-Z0237. (Unit: g/25mm) 4 Holding force Measured according to JIS-Z0237, load 1Kg, temperature 40℃,
Measured for 1 hour. 5 Pole Tack Measured at an inclination angle of 30° according to JIS-Z0237. 6 Viscosity Unless otherwise specified according to JIS-K6833,
Rotor No. 2, 12r.p. using a BM type rotational viscometer.
Measured at m. (Unit: cps) In addition, the following abbreviations will be used for each component such as monomer. 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...N-MAM , methacrylic acid methyl ester...MMA, methacrylic acid...MAA Example 1 Acrylic acid ester copolymer first stage 900 parts of BA, 100 parts of AA, 500 parts of water, sodium lauryl sulfate (Henkel Hakusui Co., Ltd., trade name: Texapon L-100) ) 0.05 part (purity equivalent) was added to make a pre-emulsion. Separately, 850 parts of water was put into a reactor equipped with a reflux condenser, a thermometer, and a stirrer. After purging the inside of the reactor with nitrogen, the temperature was raised to 80°C, 3% of the pre-emulsion was added, and then 10% of the pre-emulsion was added. 30 parts of ammonium persulfate aqueous solution was added to initiate polymerization. followed by the remainder of the pre-emulsion (97% of the total amount) and
10 parts of 10% ammonium persulfate aqueous solution continuously
The mixture was added dropwise for 4 hours at a temperature of 80±1°C. After dropping, add 0.5 part of 10% ammonium persulfate solution,
The temperature was further maintained at 80°C for 2 hours to obtain a first stage emulsion polymer. Characteristics Non-volatile content 42% Particle size 0.40μm PH 1.8 2nd stage 800 parts of HA, 200 parts of BA, 20 parts of AA Sodium polyoxyethylene alkyl phenol ether sulfate (Nippon Nyukazai Co., Ltd. trade name Newcol 560SN) 18
(purity equivalent) and 250 parts of water were added to make a pre-emulsion. Separately, 400 parts of the emulsion polymer obtained in the first stage was charged into a reactor equipped with a reflux condenser, a thermometer, and a stirrer.
After purging the inside of the reactor with nitrogen, the temperature was raised to 80°C, 1% of the pre-emulsion was added, and then 20 parts of a 10% ammonium persulfate aqueous solution was added to initiate polymerization.
Subsequently, the remainder of the pre-emulsion (99% of the total amount) and 30 parts of a 10% ammonium persulfate aqueous solution were continuously added dropwise at a temperature of 80±1° C. for 4 hours. After the dropwise addition was completed, 1 part of a 10% 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 has a non-volatile content of 71% and a viscosity of
It was 300 cps and PH2.0, with a high resin content and low viscosity. This emulsion polymer was neutralized with 25% ammonia water,
Acrylic emulsion type thickener (Nippon Acrylic Co., Ltd.
The viscosity was measured using Primal ASE-60 (trade name: Primal ASE-60).
20000cps (BM type viscometer, rotor No.4, 12r.pm
The adhesive properties of the product thickened to 30 μm (after drying) applied to a 50 μm thick polyester film were adhesive strength of 300 g/25 mm, holding power without deviation, and ball tack of 8. In addition, this thickened product was conventionally coated with an acrylic emulsion type adhesive with a solid content concentration of 50% (trade name A-2422H, manufactured by Toagosei Kagaku Kogyo Co., Ltd.) at a coating speed of 50 m/min and dried. When coating was performed using a three-roll reverse roll coater, the distance between the coating roll and metering roll was adjusted to obtain the same coating thickness as before, and a coated product in the same dry state as before was created. , we were able to increase the coating speed to 70m/min. Examples 2 to 8 The first stage composition obtained in Example 1 was used to carry out the second stage reaction. Second stage When the composition of the second stage pre-emulsion of Example 1 was changed as shown in Table 1 and the same reaction operation as in Example 1 was performed, the products shown in Table 2 were obtained.
When the adhesive performance was measured in the same manner as in Example 1, the performance was as shown in Table 2.

【table】

[Table] Examples 9 to 11 and Comparative Examples 1 to 2 Stage 1 Using the preemulsion having the composition shown in Table 3, the same reaction operation as in Example 1 was carried out to obtain the emulsion polymer shown in Table 4. Second Stage Using the emulsion polymer obtained in the first stage and using the pre-emulsion having the composition shown in Table 5, the same operations as in Example 1 were carried out to obtain the emulsion polymers shown in Table 6.

【table】

【table】

【table】

[Table] Examples 12 to 14 and Comparative Example 3 1st stage Using a pre-emulsion having the composition shown in Table 7, 600 parts of water was put into the same reactor as in Example 1, and after purging the inside of the reactor with nitrogen, the temperature was 80°C. The pre-emulsion was added in the amount shown in Table 8, and the same operations as in Example 1 were carried out to obtain emulsion polymers shown in Table 9. Second Stage Using the emulsion polymer obtained in the first stage and using a pre-emulsion having the composition shown in Table 10, the same operations as in Example 1 were carried out to obtain the emulsion polymers shown in Table 11.

【table】

[Table] *% of total amount of pre-emulsion

【table】

【table】

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[Table] Comparative Example 4 Polymerization by conventional method 900 parts of BA, 100 parts of MAA, 200 parts of water, sodium polyoxyethylene alkyl phenol ether sulfate (Nippon Nyukazai Co., Ltd., trade name Newcol)
560SN) was added to make a pre-emulsion. 200 parts of water was charged into the same reactor as in Example 1,
After purging the inside of the reactor with nitrogen, the temperature was raised to 80°C, and 3% of the pre-emulsion was added, followed by 30 parts of a 10% ammonium persulfate aqueous solution to initiate polymerization. Then add the remainder of the pre-emulsion (97% of the total amount)
80%) and 10 parts of a 10% ammonium persulfate aqueous solution
When the mixture was added dropwise for 4 hours at a temperature of ±1°C, an emulsion polymer with extremely high viscosity was obtained. Characteristic values are nonvolatile content 71%, viscosity 75000cps (BH
(Measured using a rotary viscometer rotor No. 6 and 10 rpm). Comparative example 5 1st stage 850 parts of water was charged into the same reactor as in Example 1,
Heat with stirring under a nitrogen stream until the reaction system reaches 80%
When the temperature reaches ℃, add 950 parts of BA, 50 parts of MAA, 500 parts of water.
1.5 parts of sodium lauryl sulfate and 2 parts of a 10% ammonium persulfate aqueous solution were added dropwise over 4 hours to obtain a first stage emulsion polymer. Characteristic values Non-volatile content 42% Particle size 0.08 μm Second stage 400 parts of the emulsion polymer obtained in the first stage was charged into the same reactor as in Example 1, and the same operation was carried out using the same raw materials as in Example 1. When this was carried out, an emulsion polymer with extremely high viscosity was obtained. Characteristic values Non-volatile content 70% Viscosity 45000 cps (measured at BH type rotational viscometer rotor No. 6, 10 r.p, m. 25°C) Comparative example 6 1st stage 900 parts of BA, 100 parts of AA, 250 parts of water, alkylbenzene A pre-emulsion was prepared by adding 1.5 parts of ammonium sulfonate (trade name Newcol 210S, manufactured by Nippon Nyukazai Co., Ltd.). Thereafter, the same operations as in Example 1 were performed to obtain a first stage emulsion polymer. Characteristic values Non-volatile content 42% PH 4.3 Particle size 0.05μm 2nd stage 400 parts of the emulsion polymer obtained in the 1st stage was charged into the same reactor as in Example 1. When this operation was carried out, an emulsion polymer with extremely high viscosity was obtained. Characteristic values Non-volatile content 70% Viscosity 58000 cps (measured with BH type rotational viscometer rotor No. 6, 10 r.pm at 25°C) Comparative example 7 1st stage 900 parts of BA, 100 parts of AA, 250 parts of water, octylphenoxyethoxy Sodium ethyl sulfate (Nippon Nyukazai Co., Ltd., trade name Newcol 861S) 0.009 part (pure content)
I tried to make a pre-emulsion by adding this, but although it was partially emulsified, the whole was not emulsified well. Next, this partially emulsified pre-emulsion and
An attempt was made to perform the first stage of emulsion polymerization using a mixture of water and monomers in the same manner as in Example 1, but many solid particles were generated and the emulsion polymerization could not be used for the second stage. I couldn't get anything.

Claims (1)

[Claims] 1. Obtained by emulsion polymerizing the radically polymerizable monomer in an aqueous medium using 0.001 to 0.01 parts by weight of an emulsifier per 100 parts by weight of the radically polymerizable monomer.
A highly concentrated aqueous emulsion with a resin concentration of 60% by weight or more, characterized in that a radically polymerizable monomer is further emulsion polymerized in a polymer emulsion consisting of polymer particles with an average particle size of 0.3 to 0.5 μm. Production method.