JP3434036B2 - Method for producing crosslinked polymer particles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing crosslinked polymer particles which are excellent in heat resistance, monodispersibility and dispersibility in a medium during particle synthesis.

[0002]

BACKGROUND OF THE INVENTION Crosslinked polymer particles used for various purposes can be obtained by an emulsion polymerization method, a seed emulsion polymerization method, or a dispersion suspension polymerization method. However, in the emulsion polymerization method, it is difficult to increase the particle size when the degree of crosslinking is increased to improve heat resistance, and the seed emulsion polymerization method requires several steps.
The dispersion suspension polymerization method has a problem that it is difficult to obtain particles having good monodispersity. Further, such crosslinked polymer particles are mainly polymerized and synthesized in an aqueous medium, but they often aggregate in the aqueous medium during synthesis, resulting in poor dispersibility.

[0003]

The inventors of the present invention have made earnest studies in view of the above circumstances, and as a result, have a high degree of crosslinking and are excellent in heat resistance.
The inventors have found a manufacturing method in which the particle size of crosslinked polymer particles having excellent monodispersibility and excellent dispersibility in the medium at the time of particle synthesis can be easily controlled, and the present invention has been completed.

That is, the gist of the present invention is ethylene glycol.
30-70% by weight of cold dimethacrylate, methyl ac
Relate or methyl methacrylate 2 to 20% by weight
And 20 to 70% by weight of divinylbenzene are polymerized in an aqueous medium in the presence of a water-soluble anionic polymerization initiator and an anionic emulsifier to form crosslinked polymer particles having an average particle diameter of 0.1 to 2 μm. In producing, the concentration of the water-soluble anionic polymerization initiator at the start of the reaction is 0.01% by weight or more with respect to the aqueous medium, and the concentration of the anionic emulsifier is 0.1% by weight or less with respect to the aqueous medium. In addition, a method for producing crosslinked polymer particles is characterized in that a part of the monomer is added to carry out initial polymerization, then the remaining monomer is continuously added, and then additional polymerization is carried out.

The present invention will be described in detail below. In the present invention, at least the following three components (a) to (c) are used as the polymerizable monomer that is a raw material of the crosslinked polymer particles. The ratio of each component in the (a) ethylene glycol dimethacrylate (b) acrylic acid lower alkyl ester or methacrylic acid lower alkyl ester (C) divinylbenzene crosslinked polymer particles is not particularly limited, but is preferably as follows. Is. That is, ethylene glycol dimethacrylate is preferably 30-
70% by weight, particularly preferably 40 to 70% by weight.

Acrylic acid lower alkyl ester or methacrylic acid lower alkyl ester is preferably 2 to 20% by weight, particularly preferably 5 to 10% by weight, and vinylbenzene is preferably 20 to 70% by weight.
Particularly preferably, it is 30 to 50% by weight. When the amount of ethylene glycol dimethacrylate is less than 30% by weight, the particles may be easily aggregated in the reaction system during the polymerization reaction, or the dispersibility of the obtained particles in the polyester composition may be poor. Further, when the amount of ethylene glycol dimethacrylate exceeds 70% by weight, the degree of crosslinking of the obtained particles may be low or it may be difficult to increase the particle size. When the degree of cross-linking of the cross-linked polymer particles is low, the heat resistance is poor, for example, particles are aggregated in a medium during a particle synthesis reaction, and when the obtained particles are contained in a polyester composition, a polyester composition There is a tendency that the dispersibility of the inside becomes insufficient.

If the amount of acrylic acid lower alkyl ester or methacrylic acid lower alkyl ester is less than 2% by weight, particles may aggregate in the medium during the particle synthesis reaction,
The reaction speed may become slow. If it exceeds 20% by weight, the degree of crosslinking of the obtained particles tends to be low. When the amount of divinylbenzene is less than 20% by weight, the degree of crosslinking of the obtained particles tends to be low. Also, 70
When the content is more than weight%, the particle synthesis reaction rate tends to decrease, and particles tend to aggregate in the reaction system during the reaction.
Further, a polymerizable monomer other than these three components (a) to (c) may be contained as long as it is about 1 to 5%. Examples of such a polymerizable monomer include 1,4-butanediol diacrylate, n-butyl acrylate, ethylene glycol monomethacrylate, neopentyl glycol dimethacrylate, and styrene. Especially 1, 4
When 1 to 5% of butanediol diacrylate is mixed, the dispersibility of particles in the aqueous medium of the particle synthesis reaction system is improved.

In the present invention, a part of the above monomers is initially polymerized, and then the remaining monomers are continuously added,
It is necessary to continue additional polymerization. By this additional polymerization, cross-linked polymer particles having a large particle size can be satisfactorily obtained.
The initial polymerization referred to in the present invention refers to the polymerization reaction stage until the polymerization reaction rate of the initially added monomer reaches 90 to 100%. In the present invention, the amount of monomers initially mixed with water is preferably 10 to 30% of the total amount of monomers.
In the present invention, the monomer composition used for the initial polymerization and the monomer composition used for the additional polymerization may be slightly different, but generally, the same composition is preferable. In the present invention, a water-soluble anionic polymerization reaction initiator is used as the polymerization reaction initiator. Examples of the water-soluble anionic polymerization reaction initiator include potassium persulfate, sodium persulfate, ammonium persulfate, and the like, and particularly preferable one is potassium persulfate.
The amount of the polymerization reaction initiator is such that the concentration of the initiator at the start of the reaction is 0.01% by weight or more, preferably 0.0
1 to 1% by weight. When the concentration of the polymerization initiator is less than 0.01% by weight, the particle size of the crosslinked polymer particles is too small, and the particle size can be increased by increasing the amount.
Further, a water-soluble anionic polymerization reaction initiator may be additionally added during the polymerization reaction. This is an effective method when it is desired to increase the particle size of the particles.

On the other hand, examples of anionic emulsifiers added at the start of the polymerization reaction include sodium lauryl sulfate, sodium polyoxyethylene lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and polyoxyethylene alkylphenyl ether sulfate ammonium salt. Of these, particularly preferred is sodium polyoxyethylene lauryl sulphate. The amount of the anionic emulsifier needs to be such that the anionic emulsifier concentration in the reaction system at the start of the polymerization reaction is less than the critical micelle formation concentration. That is, when the concentration is higher than the critical micelle formation concentration, the particle polymerization reaction time becomes long,
It becomes difficult to obtain particles having a large particle size. Specifically, the concentration of the anionic emulsifier in the reaction system at the start of the polymerization reaction is 0.1% by weight or less, preferably 0.1 to 0.001% by weight, more preferably water, in the reaction system. 0.0
It is from 05 to 0.05% by weight. Further, in the present invention, after the polymerization has progressed to a certain degree, it is also possible to additionally add an anionic emulsifier, particularly when the particle size of the crosslinked polymer particles is small or the particle concentration of the reaction system is high, the reaction This is an effective method for preventing particle aggregation in the system. In this case, the total amount of emulsifier used may exceed 0.1% by weight.

The timing of additional addition is preferably such that the polymerization reaction rate (initial polymerization + addition polymerization) is 5 to 90%. In addition, in terms of operation, it is desirable to perform additional polymerization after the initial polymerization. In this case, sodium lauryl sulfate is particularly preferable as the additional anionic emulsifier. The crosslinked polymer particles after polymerization, if necessary, improve the long-term dispersibility in the medium or the dispersibility in the polyester composition when added as a filler to the polyester composition. In addition, the cross-linked polymer particles may be surface-treated after the completion of the polymerization reaction. For example, surface treatment with an anionic surfactant, particularly an alkyldiphenyl ether type anionic surfactant having two or more sulfonic acid groups, is effective. The average particle size of the crosslinked polymer particles of the present invention is 0.1 to 2 μm. This average particle size can be controlled by adjusting the concentrations of the polymerization initiator and the emulsifier at the start of polymerization, the polymerization time, and the like.

If the average particle size is less than 0.1 μm, the particles tend to aggregate during the particle polymerization reaction, and when the particles are added particles for polyester film, the slipperiness of the film is insufficient. Not preferable. Also, 2
If it exceeds μm, the particle polymerization reaction time becomes extremely long, which is not practical. The polymerization temperature in the present invention is usually 20 to 100 ° C., preferably 3 for both initial polymerization and additional polymerization.
It is 0 to 90 ° C. The polymerization reaction rate is usually 90% or more, preferably 95% or more. The polymerization mixture containing the crosslinked polymer particles after polymerization is usually recovered by spray-drying the particles, or ethylene glycol is added to the polymerization mixture and water is distilled off to recover as an ethylene glycol slurry. The crosslinked polymer particles obtained by the present invention are particularly useful as additive particles for polyester films. The polyester film to which the particles are added has excellent smoothness and smoothness, and is suitable for, for example, a base film for a long time magnetic tape or a base film for a high density magnetic recording tape.

[0012]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof. The measuring methods and definitions of various physical properties and characteristics in the examples are as follows. In addition, “part” in the examples and comparative examples means “part by weight”. (1) Average particle size The maximum and minimum diameters of each particle are measured by observing the particles with a scanning electron microscope, and the arithmetic average is calculated to be the particle size (diameter) of each particle.
And The particle size was measured for at least 100 particles, and the arithmetic mean thereof was taken as the average particle size. (2) 3 g of a particle water dispersion sample in which the particle concentration in the particle-containing aqueous medium after the reaction of synthesizing the dispersible particles of the crosslinked polymer particles in the medium is adjusted to 1% by weight
600 mesh wire mesh filter (filtration area 5 cm ² )
The following evaluation criteria were used for evaluation according to the conditions filtered. Rank A (good): A total of 500 g of the particle aqueous dispersion sample can be filtered. Rank B: 250 g or more and less than 500 g of the particle water dispersion sample can be filtered. Rank C (bad): The filter is clogged when less than 250 g of the particle water dispersion sample is filtered. (3) Number of Coarse Protrusions on Polyester Film Surface Aluminum was vapor-deposited on the film surface, and measurement was performed using a two-beam interference microscope. The measurement wavelength was 0.54 μm, and the number of protrusions showing interference fringes of third order or higher was measured. The values are shown by measuring the surface 10 cm ² of the film. The better the dispersibility of the crosslinked polymer particles in the polyester, the smaller the number of such high-order coarse and coarse projections.

Example 1 [Production of cross-linked polymer particles] In 500 parts of demineralized water, 0.1 part of water-soluble polymerization initiator potassium persulfate and 0.1 part of polyoxyethylene lauryl sulfate sodium as an anionic emulsifier.
After adding 5 parts and dissolving uniformly, a mixed solution of 0.13 part of methyl methacrylate, 1.6 part of ethylene glycol dimethacrylate, 0.75 part of divinylbenzene and 0.025 part of 1,4-butanediol diacrylate. Was added. Then, at 70 ° C with stirring under a nitrogen gas atmosphere
At the stage of carrying out the polymerization reaction for 2 hours at room temperature, after adding 0.05 part of sodium lauryl sulfate, 0.53 part of methyl methacrylate and ethylene glycol dimethacrylate.
A mixed solution of 7 parts, 3.2 parts of divinylbenzene and 0.11 part of 1,4-butanediol diacrylate was continuously added dropwise to the reaction system at a constant rate over 7 hours. The average particle size of the obtained particles was 0.30 μm.

[Production of Polyester Film] 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. It takes 4 hours from the start of the reaction 230
The temperature was raised to 0 ° C. to substantially end the transesterification reaction. Next, 0.1 part of the above-mentioned crosslinked polymer particles was added as an ethylene glycol slurry, and phosphoric acid 0.03
Parts, antimony trioxide 0.003 parts, and germanium dioxide 0.002 parts were added to carry out a polycondensation reaction to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61. The obtained polymer was extruded into a sheet form from an extruder at 285 ° C., and an amorphous sheet was obtained using an electrostatic applied cooling method. Then, it was stretched 4.0 times in the longitudinal direction at 90 ° C., then stretched 3.5 times in the transverse direction at 100 ° C. with a tenter, and then again 1 time.
The film was stretched 1.2 times in the machine direction at 30 ° C. and finally heat-set at 200 ° C. to obtain a polyethylene terephthalate film having a thickness of 8 μm.

Example 2 [Production of crosslinked polymer particles] Of the production conditions shown in Example 1, 0.13 parts of methyl methacrylate and 1.3 parts of ethylene glycol dimethacrylate were added to the demineralized water before the reaction was started. A mixture of 1.1 parts of divinylbenzene and 0.025 part of 1,4-butanediol diacrylate, which was continuously added dropwise during the reaction to obtain 0.53 parts of methyl methacrylate and ethylene glycol dimethacrylate. 5.28 parts, divinylbenzene 4.57 parts and 1,4-butanediol diacrylate 0.11 parts in the same manner as in Example 1 except that the total polymerization reaction time was 10 hours. Crosslinked polymer particles having an average particle size of 0.30 μm were obtained. [Production of Polyester Film] Polyethylene terephthalate containing crosslinked polymer particles was obtained in the same manner as in Example 1 except that 0.1 part of the above crosslinked polymer particles was added as an ethylene glycol slurry, and the thickness was 8 μm. I got a film of.

Example 3 [Production of crosslinked polymer particles] Of the production conditions shown in Example 1, 0.3 parts of potassium persulfate dissolved in water before the start of the reaction and polyoxyethylene sodium lauryl sulfate content In the same manner as in Example 1 except that 0.05 part of potassium persulfate was additionally added after 6 hours of the polymerization reaction time and the total polymerization reaction time was 12 hours. Cross-linked polymer particles having a diameter of 0.50 μm were obtained.

Comparative Example 1 [Production of Crosslinked Polymer Particles] Of the production conditions, the amount of potassium persulfate dissolved in water before the start of the reaction was reduced to 0.02 part, and the amount of sodium polyoxyethylene lauryl sulfate was adjusted to 0.02 part. Crosslinked polymer particles having an average particle size of 0.30 μm were obtained in the same manner as in Example 1 except that the amount was 225 parts. However, the total polymerization reaction time took as long as 24 hours, and for reference, it was difficult to increase the particle size even if the reaction was continued for a longer time. Further, the filterability of the obtained particle water dispersion is poor,
The dispersibility of the particles was poor. [Production of Polyester Film] Polyethylene terephthalate containing crosslinked polymer particles was obtained in the same manner as in Example 1 except that 0.1 part of the above crosslinked polymer particles was added as an ethylene glycol slurry. A film having a thickness of 8 μm was obtained in the same manner as in.

Comparative Example 2 [Production of Crosslinked Polymer Particles] Of the production conditions, the amount of potassium persulfate dissolved in water before the start of the reaction was 0.2 part, and the amount of sodium polyoxyethylene lauryl sulfate was 0.75 part. Crosslinked polymer particles having an average particle size of 0.30 μm were obtained in the same manner as in Example 1 except that the amount was increased. The resulting aqueous particle dispersion had poor filterability and poor particle dispersibility. [Production of Polyester Film] Polyethylene terephthalate containing crosslinked polymer particles was obtained in the same manner as in Example 1 except that 0.1 part of the above crosslinked polymer particles was added as an ethylene glycol slurry. A film having a thickness of 8 μm was obtained in the same manner as in.

Comparative Example 3 [Production of Crosslinked Polymer Particles] Of the production conditions, 0.66 parts of methyl methacrylate, 8.3 parts of ethylene glycol dimethacrylate, 3.95 parts of divinylbenzene and 1,4-butane were added to demineralized water. Diol diacrylate 0.13
Example 1 except that 5 parts of the mixed solution was added and the monomer mixed solution was not continuously added during the reaction.
In the same manner as above, crosslinked polymer particles having an average particle size of 0.30 μm were obtained. [Production of Polyester Film] Polyethylene terephthalate containing crosslinked polymer particles was obtained in the same manner as in Example 1 except that 0.1 part of the above crosslinked polymer particles was added as an ethylene glycol slurry. A film having a thickness of 8 μm was obtained in the same manner as in. that's all,
The obtained results are summarized in Table 1 below.

[0020]

[Table 1] The abbreviations in the above table are as follows. MMA:
Methyl methacrylate; EGDM: ethylene glycol dimethacrylate; DVB: divinylbenzene;
BGDA: 1,4-butanediol diacrylate

[0021]

[Table 2]

[0022]

According to the method of the present invention, excellent heat resistance,
Crosslinked polymer particles having monodispersity can be obtained, and the dispersibility in the medium at the time of particle synthesis is excellent, and the industrial value of the present invention is high.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08F 220/20 C08F 2/22-2/30 C08F 212/36

Claims (3)

(57) [Claims] 1. Ethylene glycol dimethacrylate 3
0-70% by weight, methyl acrylate or methyl meta
2-20% by weight of acrylate and 20 of divinylbenzene
In producing crosslinked polymer particles having an average particle size of 0.1 to 2 μm by polymerizing a monomer containing 0.1 to 70% by weight in an aqueous medium in the presence of a water-soluble anionic polymerization initiator and an anionic emulsifier. , The concentration of the water-soluble anionic polymerization initiator at the start of the reaction is 0.0 with respect to the aqueous medium
1% by weight or more, the concentration of the anionic emulsifier is 0.1% by weight or less with respect to the aqueous medium, and a part of the monomer is added for initial polymerization, and then the remaining monomer is continuously added. A method for producing crosslinked polymer particles, which comprises performing additional polymerization. 2. Methyl acrylate or methylmethac
Characterized in that the relate is methyl methacrylate
The method for producing crosslinked polymer particles according to claim 1. 3. The crosslinked polymer particles are 1,4-butanedio.
Characterized by containing 1 to 5% by weight of diol diacrylate
The method for producing the crosslinked polymer particles according to claim 1 or 2.
Law.