JPH0637526B2 - Method for producing microgel with improved film-forming property - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a microgel having excellent film-forming properties.

[Prior Art and Problems to be Solved by the Present Invention] Conventionally known microgels have the drawback of poor film forming properties.

Since the microgel has a cross-linked structure, it has the advantages of excellent solvent resistance, hardness, heat-softening resistance, etc., but it has the disadvantage of poor film formation, especially film formability. ing.

For this reason, there have been many demands for microgels having excellent film-forming properties that take advantage of the features of conventional microgels.

Conventionally known microgels tended to have very poor film-forming properties as the gel content increased.

For example, a microgel having a gel content of 40 to 70% by weight cannot form a uniform and continuous film, and when the gel content becomes 70 to 96% by weight, a film which is durable even when heat-treated is formed. Do not form. Further, when the gel content is 96% by weight or more, no film is formed even if heat treatment at 150 ° C. is performed.

The present invention solves all of the problems of the prior art, excellent solvent resistance of the microgel, hardness,
It is intended to provide a method for producing a microgel having excellent film-forming property by taking advantage of heat-softening resistance.

The gel content described in the present invention means that the content of the microgel is 40%.
Dry for 16 hours at ℃ to form a film, then at 105 ℃ 3
It is heat-treated for an hour, trichlene-extracted for 3 hours using a Soxhlet extractor, and the residue is shown divided by the weight before extraction.

[Means for Solving the Problems] The present invention is directed to "the following B monomer or monomer as a seed (seed) of 100 parts by weight of the following microgel (as solid content) and without the use of an emulsifier. A method for producing a microgel with improved film-forming property, which comprises adding 1 to 100 parts by weight of a body mixture and performing two-step emulsion polymerization to form a shell around a seed.

A. Emulsifying a monomer composed of a mixture of a monomer selected from lower alkyl esters of acrylic acid or methacrylic acid and another polymerizable monomer copolymerizable with these monomers in an aqueous medium. When polymerizing, the concentration in the system is 10 ^-8 mo
Reaction of oligoester acrylate system using redox catalyst in the presence of divalent transition metal ion in the range of l / to 10 ^-6 mol / and having two or more (meth) acryloyl groups in one molecule as an emulsifier. A microgel obtained by reacting with a strong emulsifier.

B. The solubility coefficient (X) is 0.1 to 10. Does not have two or more polymerizable unsaturated groups and has a glass transition temperature of 11
A monomer or monomer mixture that forms a polymer or copolymer at 0 ° C or lower.

However, the solubility coefficient M _i : weight of each monomer m _i : solubility of each monomer in water at 20 ° C., 1
00 or more is 100, and 0.01 or less is 0. It is.

In order to solve this problem, the present inventors believe that the film forming property is poor because the microgel has a crosslinked structure,
We thought that it would be better to form a resin shell having good film-forming properties on the surface of such microgel particles, and tried to carry out two-step emulsion polymerization of various monomers using this microgel as a seed. .

As a result, they have found that the problem can be solved by carrying out a two-step polymerization of a specific monomer without using an emulsifier, and completed the present invention.

According to the invention, the gel content is in a wide range, for example 5 to
It is possible to produce a microgel having a film-forming property of 96% or more, and a microgel having a high gel content of 40% or more and particularly having a room-temperature film-forming property. It cannot be manufactured without the invention.

Thus, the fact that the high gel content microgel obtained according to the present invention has extremely good film-forming property has not been known at all in the past and could not be carried out, and was obtained for the first time by the present invention. It is a new excellent effect.

In the present invention, the gel content is 9 as a seed.
Use 0% by weight or more of microgel,
A microgel having a final gel content of 70% by weight or more and improved film-forming properties by stage emulsion polymerization is excellent in various film properties and is particularly preferable.

Further, in the present invention, it is also possible to divide the specific monomer used in the two-step emulsion polymerization into two or more and carry out the multi-step emulsion polymerization.

In the present invention, a known redox such as potassium persulfate and sodium thiosulfate having an equimolar concentration of 1.0 × 10 ^{−3 to} 1.0 × 10 ⁻² mol / is used as a polymerization initiator for producing the microgel of A. A catalyst is used, but for the production of transparent ultrafine polymer latex,
As a polymerization accelerator, the concentration in the system is 5.0 × 10 ^{−8 to} 7.5 × 1.
It is indispensable to add a trace amount of divalent transition metal ions of 0 ^-6 mol /. Particularly preferable transition metal ions are divalent copper ions such as cupric sulfate and cupric chloride,
It is a divalent iron ion such as iron (II) sulfate ammonium salt.

As the reactive emulsifier, an alkali salt of a phosphoric acid ester of oligoester (meth) acrylate having two or more (meth) acryloyl groups in one molecule or polyethylene glycol having a hydrophilic ethylene oxide group in the molecule. Di (alkylene methacrylate) phosphate, a derivative oligoester acrylate And polyoxypropylene polyoxyethylene glycol diacrylate And so on.

The reactive emulsifier (1) is an anionic phosphoric acid ester, and is easily dissolved in water when the pH is adjusted to 4 to 7 with aqueous ammonia. The reactive emulsifier (2) is a nonionic type.

Commercially available products include New Frontier A-229E and New Frontier N-250Z (both are trade names, registered trademarks of Dai-ichi Kogyo Seiyaku Co., Ltd.).

These reactive emulsifiers may be a known anionic surfactant used alone or in ordinary emulsion polymerization, for example, long-chain sodium α-olefinsulfonate, alkyldiphenyloxyethylene alkylallyl ether sulfate ester salt,
More preferably, the anionic reactive emulsifier Eleminol JS-2 (registered trademark of Mitsubishi Kasei) Latemul S-180.
It is preferably used in combination with a sulfosuccinic acid-based reactive emulsifier such as (registered trademark of Kao Corporation), and the weight composition ratio thereof is preferably 1: 3 to 3: 1. The concentration of the emulsifiers alone or in the mixture is 0.5 to 2 with respect to the aqueous medium.
0 wt% It is desirable to use in the range of 2 to 10 wt%.

The monomers used are alkyl acrylates having 1 to 12 carbon atoms in the alkyl group and methacrylic acid alkyl esters having 1 to 12 carbon atoms in the alkyl group. And a monomer copolymerizable with these, for example, styrene, vinyl acetate, a vinyl ester of a saturated carboxylic acid branched at the α-position, acrylic acid, methacrylic acid,
Itaconic acid, acrylonitrile, acrylamide, N-
Methylol acrylamide, 2-hydroxyethyl methacrylate, etc. can also be used together.

A preferable monomer composition is a weight ratio, and in the case of methyl methacrylate / butyl acrylate, 30/70 to 90/1.
0, 1 for methyl methacrylate / ethyl acrylate
0/90 to 90/10, 40/60 to 90/1 in the case of methyl methacrylate / 2-ethylhexyl acrylate
0 or the like.

The obtained microgel is ultrafine particles having a particle size of 50 nm or less, and its dispersion stability is remarkably good even when the solid content concentration in the aqueous medium is 40 to 45% by weight.

In the present invention, the monomer B for forming a shell on the surface of the microgel obtained above has a solubility coefficient (X) of 0. It must be in the range of 1-10.

The solubility coefficient (X) is calculated by the following formula.

Solubility coefficient M _i : weight of each monomer m _i : solubility of each monomer in water at 20 ° C., 1
00 or more is 100, and 0.01 or less is 0.

And, as the second condition, the monomer or the monomer mixture having no two or more polymerizable unsaturated groups must be used.
Further, as the third condition, it must be a monomer or a mixture of monomers that forms a polymer or copolymer having a glass transition temperature of 110 ° C. or lower.

If a monomer or a mixture of monomers that does not satisfy this condition is used, it is not possible to obtain the microgel having excellent film-forming properties, which is the object of the present invention.

The glass transition temperature, solubility, and solubility coefficient (X) of typical monomers are as follows.

In the present invention, as a particularly useful monomer as the monomer B, one kind selected from methyl acrylate, ethyl acrylate, butyl acrylate, 2-methoxy acrylate, 2-ethoxyethyl acrylate, methyl methacrylate, ethyl methacrylate or It is a combination of two or more kinds.

Monomers such as 2-ethylhexyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate and styrene having a solubility coefficient (X) of 0.1 or less, and acrylic acid and methacrylic acid having a solubility coefficient (X) of 10 or more, Monomers such as itaconic acid, acrylamide, N-methylol acrylamide, and 2-hydroxyethyl methacrylate cannot be used alone,
It can be used in combination.

Monomer 90.1-9 having a solubility coefficient (X) of 0.1 or less
9.9 parts by weight and solubility coefficient (X) is 10 or more, especially 10
It can be used in combination with 9.9 to 0.1 part by weight of the monomer of 0. These monomer mixtures can also be used in combination with the above particularly useful monomers.

Using 100 parts by weight or less of a monomer having a solubility coefficient (X) of 0.1 or less in combination with 100 parts by weight of the above particularly useful monomer, and a monomer having a solubility coefficient (X) of 100. It is also possible to use up to 5 parts by weight in combination with 100 parts by weight of the above particularly useful monomers.

The above-exemplified monomers and monomer mixtures have a solubility coefficient (X) of 0.1 to 10 and a glass transition temperature of 11
It is a monomer or a mixture of monomers that forms a polymer or copolymer at 0 ° C. or lower, and is particularly useful in the present invention, but is not limited thereto.

In order to carry out the two-stage polymerization of the B monomer using the A microgel as a seed, 100 parts by weight of the solid content of the microgel is used.
1 to 100 parts by weight of the monomer or mixture of monomers B may be emulsion polymerized without using an emulsifier, preferably using a redox polymerization catalyst such as potassium persulfate and sodium thiosulfate. If an emulsifier is used, it should never be used as the B monomer will complete the formation of new particles.

[Effect] The microgel produced by the method of the present invention and having improved film-forming property has excellent adhesiveness, and the film obtained by drying at room temperature and heat-treating as necessary has solvent resistance, hardness and heat-softening resistance. It has excellent properties.

It also has excellent water whitening resistance and film tensile strength.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1 100 equipped with a gas inlet pipe, a reflux condenser and a stirring device
Using a 0 ml four-necked frothable flask, distilled water 48
New Frontier A22 as a reactive emulsifier in 0 ml
20 g of 9E (registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.) is dissolved and 28
% Ammonia water is added in a small amount to adjust the pH and keep at 50 ° C.
As a polymerization monomer, 270 g (mixing ratio 60:40) of a mixed monomer of butyl acrylate and methyl methacrylate was dispersed and emulsified in a polymerization flask by 27 g (10% by weight of the mixed monomer) to maintain a constant stirring state. However, a redox initiator composed of an equimolar amount of potassium persulfate-sodium thiosulfate in the presence of a trace amount of copper sulfate (concentration in system 1.0 × 10 ⁻⁷ mol /) (concentration in system 3.0 × 10 ^{− 3} mol /
) At 50-60 ° C. and pH 4-7 to start the first stage polymerization. Then, the remaining 243 g of the mixed monomer was added dropwise over 120 minutes to carry out polymerization while preventing the temperature rise due to the heat of polymerization. Polymerization was carried out for 90 minutes to complete the first stage polymerization to obtain a microgel.

The gel content of the obtained microgel was 94% or more, as is clear from Comparative Example 1. The average particle size was 30 nm.

A redox initiator (concentration in the system: 6.0 × 10 ⁻⁴ mol /) consisting of equimolar amount of potassium persulfate-sodium thiosulfate was newly added to the obtained microgel, and the mixture was heated at 50 ° C. to 6 ° C.
While maintaining the temperature at 0 ° C., 30 g of ethyl acrylate was added dropwise over 15 minutes to carry out the second-stage polymerization.
Polymerization was carried out for 0 minutes, a small amount of 28% ammonia water was added to adjust the pH, and the second-stage polymerization was completed to obtain a microgel having improved film-forming properties.

The microgel with improved film-forming property has a solid content concentration of 39.5% by weight, a viscosity of 60 cP, an average particle size of 32 nm, and a gel content of 85.
%Met.

-Viscosity was measured with a BL type viscometer at 12 rpm and 25 ° C.

-The average particle size was measured by the turbidity method.

・ Gel content is 40 ℃ × 16hr.
A sample heat-treated at 05 ° C. for 3 hours was used as a sample, and heat extraction was performed for 3 hours in a Soxhlet using trichlene as a solvent. From the extraction residue after re-drying, the gel content was calculated by the following formula.

Comparative Example 1 Only the first-stage polymerization was carried out in the same manner as in the first-stage polymerization of Example 1 except that 300 g of the mixed monomer used in the first-stage polymerization of Example 1 was used. A small amount of aqueous ammonia was added to adjust the pH to obtain a microgel.

The microgel has a solid content concentration of 40.3% by weight and a viscosity of 70c.
P, average particle size 30 nm, gel content 94%.

Examples 2 to 7 In Example 1, the amounts of the mixed monomers used in the first-stage polymerization and the types and amounts of the monomers used in the second-stage polymerization were changed as shown in Table 1. A microgel having an improved film-forming property was obtained in the same manner as in Example 1 except for the above.

The physical properties of the obtained microgel having improved film-forming properties are shown in Table 1.

As is clear from Comparative Example 1, the gel content of the microgels obtained by the first-stage polymerization in Examples 1 to 7 was 94% or more.

Comparative Examples 2 to 7 In Example 1, the amounts of the mixed monomers used in the first-stage polymerization and the types and amounts of the monomers used in the second-stage polymerization were changed as shown in Table 2. A microgel was obtained in the same manner as in Example 1 except that the following conditions were applied.

Comparative Example 2 is an example using a mixed monomer having a glass transition temperature of 110 ° C. or higher.

Comparative Example 3 is an example using a mixed monomer having a solubility coefficient (X) of 10 or more.

Comparative Example 4 is an example using a mixed monomer having a solubility coefficient (X) of 0.1 or less.

Comparative Example 5 is an example in which an emulsifier was used in combination in the second-stage polymerization, although the glass transition temperature and the solubility coefficient were within the ranges.

Comparative Example 6 is an example in which the glass transition temperature and the solubility coefficient are within the ranges, but the amount of the monomer used is 100 parts by weight or more.

Comparative Example 7 uses the reactive emulsifier of Comparative Example 6 in an amount of 20 g.
Was reduced to 10 g to lower the gel content and the second stage polymerization was carried out.

Example 8 100 equipped with gas inlet tube, reflux condenser and stirring device
Using a 0 ml four-necked frothable flask, distilled water 48
New Frontier A22 as a reactive emulsifier in 0 ml
16 g of 9E (registered trademark of Dai-ichi Kogyo Seiyaku Co., Ltd.) was dissolved and 2
A small amount of 8% ammonia water is added to adjust the pH, and the temperature is kept at 50 ° C. 240 g of a mixed monomer of butyl acrylate and methyl methacrylate as a polymerization monomer (mixing ratio 60:40)
First, 24 g (10% by weight of the mixed monomer) was dispersed and emulsified in a polymerization flask, and a certain amount of copper sulfate (concentration in the system was 1.0 × 10 ⁻⁷ mol /) was added while maintaining a constant stirring state. And a redox initiator consisting of an equimolar amount of potassium persulfate-sodium thiosulfate (concentration in system: 3.0 × 10 ⁻³ mol
/) To start the first stage polymerization at 50 to 60 ° C. and pH 4 to 7. Then, 216 g of the remaining mixed monomer was added dropwise over 120 minutes to carry out polymerization while preventing the temperature from rising due to the heat of polymerization. Polymerization was carried out for 90 minutes to complete the first stage polymerization to obtain a microgel.

As is clear from Comparative Example 8, the gel content of the obtained microgel was 80% or more.

A redox initiator (concentration in the system: 6.0 × 10 ⁻⁴ mol /) consisting of equimolar amount of potassium persulfate-sodium thiosulfate was newly added to the obtained microgel, and the mixture was heated at 50 ° C. to 6 ° C.
While maintaining the temperature at 0 ° C., 60 g of ethyl acrylate was added dropwise over 15 minutes to carry out the second-stage polymerization.
Polymerization was carried out for a minute, a small amount of 28% ammonia water was added to adjust the pH, and the second-stage polymerization was completed to obtain a microgel having improved film-forming properties.

The microgel with improved film-forming property has a solid content concentration of 39.5% by weight, a viscosity of 65 cP, an average particle size of 33 nm, and a gel content of 62.
%Met.

Comparative Example 8 300 parts of the mixed monomer used in the first step of Example 8 was used.
Only the first-stage polymerization was performed in the same manner as in the first-stage polymerization of Example 8 except that g was used, and 28% ammonia water was added in a small amount to adjust the pH to obtain a microgel.

Microgel has a solid content of 39.6% by weight and a viscosity of 60 cP
The average particle size was 32 nm and the gel content was 80%.

Example 9 100 equipped with gas inlet tube, reflux condenser and stirring device
Distilled water 45 using a 0 ml four-necked frothable flask
New Frontier A22 as a reactive emulsifier in 0 ml
Dissolve 5 g of 9E (registered trademark of Dai-ichi Kogyo Seiyaku Co., Ltd.)
% Ammonia water is added in a small amount to adjust the pH, and the temperature is kept at 50 ° C. 240 g of a mixed monomer of butyl acrylate and methyl methacrylate as a polymerization monomer (mixing ratio 60:40)
First, 24 g (10 wt% of the mixed monomer) was dispersed and emulsified in the polymerization flask, and while maintaining a constant stirring state,
A redox initiator composed of an equimolar amount of potassium persulfate-sodium thiosulfate in the presence of a trace amount of copper sulfate (concentration in system 1.0 × 10 ⁻⁷ mol /) (concentration in system 3.0 × 10 ⁻³ mo
The first stage polymerization is initiated at 50-60 ° C. at a pH of 4-7. Then, 216 g of the remaining mixed monomer was added dropwise over 120 minutes to carry out polymerization while preventing the temperature from rising due to the heat of polymerization. 90 minutes of polymerization to complete the first stage polymerization,
A microgel was obtained.

As is clear from Comparative Example 9, the gel content of the obtained microgel was 52% or more.

A redox initiator (concentration in the system: 6.0 × 10 ⁻⁴ mol /) consisting of equimolar amount of potassium persulfate-sodium thiosulfate was newly added to the obtained microgel, and the mixture was heated at 50 ° C. to 6 ° C.
While maintaining the temperature at 0 ° C., 60 g of ethyl acrylate was added dropwise over 15 minutes to carry out the second-stage polymerization.
Polymerization was carried out for a minute, a small amount of 28% ammonia water was added to adjust the pH, and the second-stage polymerization was completed to obtain a microgel having improved film-forming properties.

The microgel having improved film-forming property has a solid content concentration of 39.9% by weight, a viscosity of 10 cP, an average particle diameter of 40 nm, and a gel content of 35.
%Met.

Comparative Example 9 The mixed monomer used in the first step of Example 9 was 300
Only the first-stage polymerization was carried out in the same manner as in the first-stage polymerization of Example 9 except that g was used, and a small amount of 28% aqueous ammonia was added to adjust the pH to obtain a microgel.

The microgel has a solid content concentration of 40.2% by weight and a viscosity of 40c.
P, average particle size 34 nm, gel content 52%.

Test Example 1 Microgels having improved film-forming properties obtained in Examples 1 to 9,
And the microgels obtained in Comparative Examples 1 to 5 and 7 to 9 were tested for appearance of dried film, water whitening resistance of film, solvent resistance of film, tensile strength and elongation of film by the following methods. The test results are shown in Table 3.

-Appearance of film After drying for 16 hours at 40 ° C so that the film thickness is 0.2 mm, observe the state of film formation.

×: There are many small cracks.

C: Some cracks are recognized.

○: A uniform film that is transparent and has no cracks.

-Water whitening resistance of film: A film dried at 40 ° C for 16 hours is immersed in room temperature water and the whitening state of the film is observed.

X: Whitening or swelling of the film.

Δ: Whitening is slightly observed after 48 hours.

○: No abnormality was observed even after 48 hours.

・ Solvent resistance of the coating 40 so that the thickness of the coating is 0.1mm on the glass plate.
A film is formed by drying at 16 ° C. for 16 hours, and a few drops of xylene are dropped on the film. Observe the state when the xylene was dropped and the state of the film after the xylene was volatilized.

×: The film is completely dissolved by dripping xylene, or innumerable cracks are generated in the film after volatilizing xylene.

△: A little shrinkage is observed in the xylene dropping part of the film.

○: No abnormality is found on the film.

・ Tensile strength and elongation of the film: A film with a thickness of 0.2 mm was prepared under the drying conditions of 40 ° C and 16 hours, left in a constant temperature and humidity chamber (20 ° C, 65RH) for 24 hours or more, and pulled by an autograph. Measure strength and elongation.

・ Adhesion of film 40 on the glass plate so that the film thickness is 0.1mm.
After drying at 16 ° C. for 16 hours to form a film and cross-cutting, cellophane tape is pressure-bonded and peeled off to observe the state.

×: Completely peeled.

Δ: Some peeling was observed.

○: No peeling occurred.

Example 10 100 equipped with gas inlet tube, reflux condenser and stirring device
Using a 0 ml four-necked frothable flask, distilled water 48
New Frontier A22 as a reactive emulsifier in 0 ml
20 g of 9E (registered trademark of Dai-ichi Kogyo Seiyaku Co., Ltd.) was dissolved and 2
A small amount of 8% ammonia water is added to adjust the pH, and the temperature is kept at 50 ° C. 240 g of a mixed monomer of butyl acrylate and methyl methacrylate as a polymerization monomer (mixing ratio 60:40)
First, 24 g (10% by weight of the mixed monomer) was dispersed and emulsified in a polymerization flask, and while maintaining a constant stirring state,
A redox initiator consisting of an equimolar amount of potassium persulfate-sodium thiosulfate in the presence of a trace amount of copper sulfate (concentration in system 1.0 × 10 ⁻⁷ mol /) (concentration in system 3.0 × 10 ⁻³ mo
The first stage polymerization is initiated at 50-60 ° C. at a pH of 4-7. Then, 216 g of the remaining mixed monomer was added dropwise over 120 minutes to carry out polymerization while preventing the temperature from rising due to the heat of polymerization. 90 minutes of polymerization to complete the first stage polymerization,
A microgel was obtained.

The gel content of the obtained microgel was 94% or more.

A redox initiator (concentration in the system: 6.0 × 10 ⁻⁴ mol /) consisting of equimolar amount of potassium persulfate-sodium thiosulfate was newly added to the obtained microgel, and the mixture was heated at 50 ° C. to 6 ° C.
While maintaining the temperature at 0 ° C., 60 g of methyl methacrylate was added dropwise over 15 minutes to carry out the second-stage polymerization, and further 6
Polymerization was carried out for 0 minutes, a small amount of 28% ammonia water was added to adjust the pH, and the second-stage polymerization was completed to obtain a microgel having improved film-forming properties.

The microgel with improved film-forming properties has a solid content concentration of 39.5% by weight, a viscosity of 70 cP, an average particle diameter of 31 nm, and a gel content of 85.
%Met.

Test Example 2 For the microgel obtained in Example 10 with improved film-forming property and the microgel obtained in Comparative Example 1, 1 film was formed.
In the same manner as in Test Example 1 except that heat treatment was performed at 50 ° C. for 20 minutes, the appearance of the film, the water whitening resistance of the film, the solvent resistance of the film,
The adhesion of the coating was tested.

The test results are shown in Table 4.

Claims (1)

[Claims] 1. A seed (seed) of 100 parts by weight of the following microgel (converted to solid content) of 1 to 100 parts by weight of the monomer or monomer mixture of the following B without using an emulsifier. A method for producing a microgel having improved film-forming properties, which comprises adding and performing two-step emulsion polymerization to form a shell around a seed. A. Emulsifying a monomer composed of a mixture of a monomer selected from lower alkyl esters of acrylic acid or methacrylic acid and another polymerizable monomer copolymerizable with these monomers in an aqueous medium. When polymerizing, the concentration in the system is 10 ^-8 mo
Reaction of oligoester acrylate system using redox catalyst in the presence of divalent transition metal ion in the range of l / to 10 ^-6 mol / and having two or more (meth) acryloyl groups in one molecule as an emulsifier. A microgel obtained by reacting with a strong emulsifier. B. The solubility coefficient (X) is 0.1 to 10. Does not have two or more polymerizable unsaturated groups and has a glass transition temperature of 11
A monomer or monomer mixture that forms a polymer or copolymer at 0 ° C or lower. However M _i : weight of each monomer m _i : solubility of each monomer in water at 20 ° C., 1
00 or more is 100, and 0.01 or less is 0.