JPS59172511A - Production of latex - Google Patents

Abstract

PURPOSE:To facilitate the production of a latex having a large particle diameter and being excellent in flowability, etc., by emulsion-polymerizing an aliphatic conjugated diene monomer, adding the same monomer when the polymer conversion reaches a specified value and polymerizing the reaction mixture. CONSTITUTION:100pts.wt. polymerizable material comprising an aliphatic conjugated diene (e.g., 1,3-butadiene) or its mixture with an ethylenically unsaturated monomer (e.g., methyl acrylate or acrylonitrile) is emulsion-polymerized in the presence of 50-100pts.wt. water. When the polymer conversion in this emulsion polymerization system reaches 30-80%, 10-50pts.wt. same polymerizable material as that initially charged is added to the emulsion polymerization system, and the reaction mixture is further polymerized to form particles of an average particle diameter >=0.25mum. In this way, the purpose latex suitable for use as a base for graft polymerization is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing latex with large particle size.

Generally, when the particle size of the polymer particles in a conjugated diene polymer latex (hereinafter referred to as "latex particle size") is large, there are the following advantages.

(a) When such a latex is used as a graft base for a synthetic rubber derivative obtained by graft polymerization, such as ABS resin, the resin has high impact resistance.

(b) Since the viscosity of the latex is low, it has good fluidity and is easy to handle even when the latex concentration is considerably high.

However, the latex particle size of conjugated diene polymers obtained by ordinary emulsion polymerization methods is usually 0.05 to 0.1.
5 μm, and it is possible to increase the latex particle size to some extent by adjusting the emulsifier layer, etc., but even in this case, the maximum is about 0.25 μm, and it is not necessary to increase the latex particle size. It can't be called a big thing.

Conventionally, in order to obtain latex with a large latex particle size, a special emulsifier or additive is used, a latex with a small latex particle size is polymerized in advance, and this latex is added to a polymerization reaction system to perform polymerization. So-called seed polymerization method, or latex after polymerization,
Methods that have been used include chemical treatments such as adding acids, alkalis, and salts, or physical treatments such as stirring, pressurization, and freezing to cause latex particles to coalesce and enlarge the particles. .

However, these methods have the following drawbacks. In other words, methods that use special emulsifiers and additives reduce the dispersion stability of the latex and cause multiple latex particles to coalesce.As a result, coagulates often occur in the latex, making it difficult to obtain a homogeneous latex. can't get it. Furthermore, increasing the amount of special components other than polymers in latex may make the chemical properties of the latex unfavorable.

In addition, the seed polymerization method not only requires a separate process to produce latex with a small latex particle size, but also requires suppressing the formation of latex particles with lr irregularities in the A section of the seed pedestal. However, since such conditions are delicate, there are drawbacks such as the fact that the setting is generally difficult.

Furthermore, in the method of enlarging latex particles by chemical or cutting treatment, unnecessary coagulation is likely to occur during the enlarging operation, and the latex particle size is not uniform. Moreover, it has many drawbacks, such as requiring costly equipment and processes due to its enlargement.

As a result of intensive research into a method for producing latex with large latex particle diameters that does not have the above-mentioned drawbacks, the inventors of the present invention discovered that the synthesis of latex particles can be improved by further adding 7-mer in the middle of the polymerization reaction. The inventors have found that this can be effectively achieved, and have completed the present invention based on this detailed study.

In other words, the object of the present invention is to produce homogeneous latex particles with large particle size and excellent fluidity, particularly in graft polymerization, by simple operation without the need for new equipment or complicated processes. An object of the present invention is to provide a method for producing latex suitable for use as a base.

The present invention is characterized by the polymerizable material 100 comprising an aliphatic conjugated diene or a mixture of an aliphatic conjugated diene and an ethylenically unsaturated monomer. Place the container in 50~100 lOO of water.
Emulsion polymerization is carried out in the presence of parts by weight, and when the polymerization conversion rate in this emulsion polymerization system is 30 to 80%,
The point is that 10 to 50 parts by weight of the same polymerizable material as the above polymerizable material is added to the emulsion polymerization system and further polymerized to form particles having an average particle size of 0.25 μm or more.

Next, the present invention will be specifically described.

In the present invention, first, 100 parts by weight of a polymerizable material consisting of an aliphatic conjugated diene or a mixture of an aliphatic conjugated diene and an ethylenically unsaturated monomer is emulsion polymerized in the presence of 50 to 100 parts by weight of water, Subsequently, at a stage when the reaction conversion rate in this emulsion polymerization system reached 30 to 80%, a 10 to 50 fold part of the same polymerizable material as the above polymerizable material was newly added to the emulsion polymerization system. The average particle size of the latex particles is from 0.25 μm to approximately 0.5 μm, and from 0.27 to 0.4 μm.
Manufactures latex.

The aliphatic conjugated diene is a compound mainly having 4 or 5 carbon atoms in its main chain, and includes 1,3-butadiene, isoprene, chloroprene, 1-chlorobutadiene, etc., and particularly 1.3-butadiene. - Butadiene is preferred.

Examples of the ethylenically unsaturated monomer include styrene, α-
Examples include aromatic vinyl compounds such as methylstyrene and vinyltoluene, acrylic esters such as methyl acrylate and ethyl acrylate, methacrylic esters such as methyl methacrylate and ethyl methacrylate, and vinyl cyanide compounds such as acrylonitrile and methacrylonitrile. However, styrene and methyl methacrylate are sometimes preferred.

Among them, it is also possible to use an ethylene monomer having a carboxyl group, but if the proportion of this monomer used becomes large, the dispersion stability of the latex obtained by the first stage polymerization becomes extremely high. As a result, coalescence of latex particles is suppressed, and an increase in the latex particle size is hindered, so its use should rather be avoided.

The amount of water used as a dispersion medium for emulsion polymerization is 50~
The amount is 100 parts by weight, preferably 50 to 90 parts by weight. If the amount used is less than 50 parts by weight, the dispersion stability of the dispersion system will decrease, while if it exceeds 100 parts by weight, it will be impossible to obtain a large latex particle size, both of which will cause practical problems. Although it is preferable to use this water all at once at the start of the reaction, it may be added in portions or continuously to the polymerization reaction system as long as it does not cause any trouble.

In addition, when the polymerization conversion rate in the polymerization reaction reaches 30 to 80 parts, the weight of the newly added polymerizable material is 10 to 50 parts per 100 parts of the polymerizable material at the start of the reaction.
fii part. It is possible to adjust the latex particle size of the obtained latex by changing the concentration of this polymerizable material, but if the amount added is less than 10 points, the effect of increasing the latex particle size is small;
If the reaction time exceeds the critical limit, the time required for the reaction becomes longer and is not practical.

The timing of additional addition of the polymerizable material is not particularly limited as long as the polymerization conversion rate in the polymerization reaction is within the range of 30 to 80%, and as long as this condition is satisfied, the timing of the addition can be changed. However, if the polymerization conversion rate is outside this range, that is, if the polymerization conversion rate is 30
Even if the polymerizable material is added below 80% or above 80%, there is almost no effect of increasing the latex particle size.

In the latex manufacturing method according to the present invention, a normal emulsion polymerization method can be used, and the reaction temperature is 450 or higher,
Preferably it is 60C or higher. In order to further enhance the effect of increasing the latex particle size in the present invention, 1 part by weight or more of an alkali metal salt, such as sodium chloride, potassium chloride, sodium phosphate, potassium phosphate, sodium carbonate, carbonic acid, potassium, etc., may be added to the reaction system. It is desirable to add.

The amount of emulsifier used in emulsion polymerization is preferably 1 to 4 parts by weight. If the amount used is less than 1 part by weight, the dispersion stability of the polymerizable material will be insufficient and the reaction rate will be extremely low, while if it exceeds 4 parts by weight, the fractional stability of the resulting latex will be high. This makes it difficult for the latex particles to coalesce with each other, which undesirably reduces the effect of increasing the latex particle size. Examples of the emulsifier include disproportionated rosin acid and alkali metal salts of higher fatty acids, and these may be used alone or in combination of two or more.

It is still desirable to add a formaldehyde condensate of sodium naphthalene sulfone as an auxiliary emulsifier.

Examples of the polymerization initiator include water-soluble peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate;
Alternatively, examples thereof include organic hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, and para-menthane hydroperoxide.

There is no restriction on the use of additives such as chain transfer agents such as 2.tertiary dodecyl mercaptan.

As described above, according to the present invention, the average particle size of latex particles can be reduced to 0 by the simple operation of adding polymerizable material without requiring special equipment or complicated processes.
．． Very large particles of 25 to 0.45 μm can be obtained reliably. Incidentally, if emulsion polymerization is performed without additionally adding a polymerizable material, the latex particle size of the obtained latex will be 0.1 to 0.2 μm smaller in average particle size than when additionally adding a polymerizable material. Become.

The cause of this effect of increasing the latex particle size in the present invention is not necessarily clear, but it is clearly larger than if it were considered that the polymer particles that had already been generated by the additional addition of the polymerizable material were further grown by polymerization. Since it has latex particles and a container, it is thought that the additionally added polymerizable material causes the latex particles that have already been formed to coalesce together.

The latex having a large latex particle size obtained by the production method of the present invention has the following features. (a) This latex can be used for various purposes, but in particular, it can be used as a graft base for synthetic rubber derivatives obtained by graft polymerization, such as ABS resin, to make this synthetic rubber derivative highly impact resistant. It can be a sexual thing.

(b) This latex has a low viscosity and good fluidity even when the latex concentration is quite high.
Easy to handle and cost effective in various uses and processes.

Examples of the present invention will be described below, but the present invention is not limited thereto.

Note that "parts" represent parts by weight.

Example 1 (1) Production of latex Materials having the following composition were placed in a stainless steel autoclave equipped with a stirrer, and a polymerization reaction was carried out at a temperature of 60C.

1.3-Butadiene 100 parts water
70 parts disproportionated potassium rosinate
2 parts potassium oleate 0.4
Part formalin condensate of sodium naphthalene sulfonate 0.2 parts Potassium carbonate 1.2 parts Potassium persulfate
0.3 parts tertiary dodecyl mercaptan
0.2 parts When the polymerization conversion rate in this reaction reached 50 parts, another 25 parts of 1,3-butadiene was added to make the total amount of 1,3-butadiene 125 parts (from that at the start of the reaction). The reaction was further continued until the polymerization conversion rate with respect to the additionally added phase) reached 90% to obtain a latex. Note that the time required for the entire reaction was 50 hours. When the latex particle size and amount of coagulated material of the latex thus obtained were measured, the latex particle size was as large as 0.29 μm, and the amount of coagulated material was 0.0 μm.
The content was very low, less than 11% by weight. Note that these values were obtained by the following method.

, Latex particle size: Average particle size measured by observing latex treated with osmic acid using an electron microscope.

The weight of the coagulated product obtained by filtering the coagulated latex using a 120-mesh filter medium.

(2) Production of ABS resin 25 parts of the latex obtained in the above method and a substance having the following composition were placed in a stainless steel autoclave equipped with a stirrer, and a polymerization reaction was carried out at a temperature of 60C for 4 hours.

Styrene 50 parts Acrylonitrile 25 parts Disproportionated potassium rosinate
2 parts Potassium hydroxide 0.1 part Glucose 0.5 part Sodium birophosphate 0.5f [S ferrous sulfate
0.02 parts tertiary dodecyl mercaptan 0.5fil water
200 parts cumene hydroperoxide 0.5 part Next, 2,4 parts was added to the latex obtained by this reaction.
One part of -di-t-butyl para-cresol was added to the mixture, and dilute sulfuric acid was further added to solidify it, followed by filtration, washing with water, and drying to obtain a resin powder. This resin powder was pelletized using a 40-inch diameter extruder at a temperature of 200 tons and a rotation speed of 6 orpm, and then pelletized using a 5-ounce injection molding machine at a temperature of 2
AB molded at 00C, gauge pressure 85kV'crIr2
A molded piece of S resin was obtained.

The flow value and impact strength of this molded piece of ABS resin were measured. The results are shown in Table 1 along with other data. Note that the flow value and impact resistance are values measured by the following method.

Flow tester: Koka type flow tester (nozzle diameter law, length 2m, load 30kg/crr;', manufactured by Shimadzu Corporation)
Direct measurement at a temperature of 200C.

Impact strength: Measured according to ASTM D256 at a temperature of 23C. Examples 2-5. Comparative Examples 1 to 3 Four types of examples were compared in exactly the same manner as in Example 1, except that the regression addition filter or additional addition timing (polymerization conversion rate of the reaction system) of the single substance was set to the values shown in Table 1. A total of 74 latexes of three types were obtained for the examples.

For each of these latexes, the particle size of the latex and the quality of the coagulated material were measured by the method described above. The results are the first
Shown in the table. Furthermore, using these seven types of valley latex as a graft base, ABS was prepared in exactly the same manner as in Example 1.
The flow value and impact strength of the resin molded pieces obtained were measured by the methods described above. The results are also shown in Table 1.

According to the above experimental results, in Example 2 of the present invention, the effect of increasing the latex particle size was great, moreover, almost no coagulum was generated in the latex, and furthermore, the fluidity and impact properties were excellent. It turned out to be ABS resin.

Comparative Example 4 A latex was obtained in exactly the same manner as in Example 1, except that 40 parts of water was used instead of 70 parts in the production of latex in Example 1. When the latex particle size of this latex and the coagulum were measured using the method described above, the latex particle size was 0.30 μm, which was very satisfactory, but the coagulum was 4.2% by weight, which was large. It's not practical.

Comparative Example 5 70 parts of water in the production of latex of Example 1 was replaced with 110 parts of water.
A latex was obtained in the same manner as in Example 1, except that the latex particle size and coagulum of this latex were measured by the method described above, and it was found that no coagulum remained.
Although the latex particle size was small at 0.11% by weight and no problem, the latex particle size was as small as 0.22 μm, which was disappointing.

Examples Example 1 Polymerizable materials in the production of latex 1.3
- 100 parts of butadiene was mixed with 90 parts of 1.3-butadiene and 10 parts of styrene, and 25 parts of the polymerizable material to be added was 22.5 parts of 3-butadiene and 2.5 parts of styrene. A latex was obtained in the same manner as in Example 1 except for the above. When the latex particle diameter and the amount of coagulated material of this latex were measured by the method described above, the latex particle size was as large as 0.31 μm, and the amount of coagulated material was Good results were obtained with an amount of 0.01% by weight or less.

Furthermore, a molded piece of ABS resin was obtained in the same manner as in Example 1 except that this latex was used as the graft base.

This molded piece of ABS resin was processed using the method described above.
When Ih11t% impact strength was measured, the flow value was 12.
*1 O-3 cc/sec, and the impact strength was 49 kg (Company) - good results were obtained in both cases.

Comparative Example 6 A latex was obtained in exactly the same manner as in Example 6, except that no additional polymerizable material was added. When the latex particle size and coagulum of this latex were measured using the method described above, the coagulum was fine at 0.01 μm or less, which was not a problem, but the latex particle size was 0.21 μm, which was small. Ta.

Furthermore, a molded piece of ABS resin was obtained in exactly the same manner as in Example 1 except that this latex was used as kraft paste.

When the l&dynamic value and #yield strength of this molded piece of ABS resin were measured using the methods described above, the flow value was 10X.
The impact strength was 10-3 CC/sec and 39 hits/slip.

Claims (1)

[Claims] 1) Polymerizable material 100 made of an aliphatic conjugated diene or a mixture of an aliphatic conjugated diene and an ethylenically unsaturated monomer
parts by weight were subjected to emulsion polymerization in the presence of 50 to 100 parts by weight of water, and the polymerization conversion rate in this emulsion polymerization system was 30.
~80%, add 10 to 50 parts by weight of the same polymerizable material as the above polymerizable material to the emulsion polymerization system and further polymerize to form particles with an average particle size of 0.25 μm or more. A method for producing latex characterized by: 2) The aliphatic conjugated diene is 1,3-butadiene, and the ethylenically unsaturated monomer is selected from aromatic vinyl compounds, acrylic esters, meth, lyrylic esters, acrylonitrile, and methacrylonitrile.
2. A method for producing latex according to claim 1, which is a process for producing latex.