JP5063953B2 - Aqueous dispersion and method for producing the same - Google Patents

Description

  The present invention relates to an aqueous dispersion of an olefinic thermoplastic resin and a method for producing the same.

  Aqueous dispersions of olefinic thermoplastic resins are used as adhesives, paints, and the like in order to impart properties such as adhesion, corrosion resistance, gas barrier properties, chipping resistance, and heel mark resistance to articles. Specifically, it is used as a moisture-proofing agent, a film forming agent, a coating agent, a fiber treatment agent, a heat sealing agent, a binder, a primer, and the like. Examples of the article imparted with the above characteristics by the aqueous dispersion include painted articles, coated articles, laminates, inks, cosmetics, and adhesive products. Further, as the aqueous dispersion of the olefin-based thermoplastic resin, a modified olefin-based thermoplastic resin in the aqueous dispersion by crosslinking or graft polymerization is used.

The following methods are known as methods for producing an aqueous dispersion of an olefinic thermoplastic resin.
(1) A method of obtaining an aqueous dispersion by polymerizing radically polymerizable monomers in an aqueous medium by an emulsion polymerization method.
(2) A method of dispersing a kneaded material composed of a thermoplastic resin such as polyolefin and a water-soluble polymer in water (Patent Document 1).
(3) A method in which an aqueous dispersion is obtained by melt-kneading a polyolefin and a carboxyl group-containing polyolefin, and then supplying water or a basic substance-containing aqueous solution to cause phase inversion (Patent Documents 2 and 3).

The method (1) is an advantageous method because an aqueous dispersion can be obtained directly with a relatively small average particle diameter, but it is an advantageous method. Are limited. Therefore, the use of the obtained aqueous dispersion is limited.
On the other hand, according to the methods (2) and (3), various aqueous dispersions can be produced without limitation on the type of olefinic thermoplastic resin.
However, there are problems that the obtained aqueous dispersion contains a large amount of non-emulsified matter, the storage stability and chemical stability of the aqueous dispersion are poor, and the water resistance of the obtained coating film is insufficient. Therefore, the obtained aqueous dispersion is not practically usable.
Japanese Patent Laid-Open No. 51-12835 Japanese Patent Publication No. 7-8933 Japanese Examined Patent Publication No. 7-96647

  Therefore, the object of the present invention is that there is no restriction on the type of olefinic thermoplastic resin, there are few unemulsified products, excellent storage stability and chemical stability, and olefinic thermoplastic that can form a coating film with excellent water resistance. An object is to provide an aqueous dispersion of a resin and a method for producing the same.

The method for producing an aqueous dispersion of the present invention includes an olefinic thermoplastic resin (A), 1 to 20 parts by mass of maleic anhydride-modified polyolefin (B) with respect to 100 parts by mass of the olefinic thermoplastic resin (A), , A step of melt-kneading 1 to 15 parts by mass of α-olefin sulfonate (C) with respect to 100 parts by mass of the olefin-based thermoplastic resin (A) to obtain a melt-kneaded product, and subsequently performing melt-kneading The olefin-based thermoplastic resin (A) is injected into the melt-kneaded product under a pressure higher than the saturated vapor pressure of water at a melt-kneading temperature with respect to 100 parts by mass of the olefin-based thermoplastic resin (A). It has a step of obtaining an aqueous dispersion dispersed in water, and a step of diluting the aqueous dispersion with water to obtain an aqueous dispersion.

The aqueous dispersion of the present invention is obtained by the method for producing an aqueous dispersion of the present invention.
The aqueous dispersion of the present invention preferably has a solid content concentration of 30 to 60% by mass.

The aqueous dispersion of the olefinic thermoplastic resin of the present invention has no limitation on the type of the olefinic thermoplastic resin, there are few non-emulsified products, excellent storage stability and chemical stability, and excellent water resistance. Can be formed.
According to the method for producing an aqueous dispersion of an olefinic thermoplastic resin of the present invention, there is no limitation on the type of the olefinic thermoplastic resin, there are few non-emulsified products, excellent storage stability and chemical stability, and water resistance. It is possible to easily produce an aqueous dispersion of an olefin-based thermoplastic resin that can form an excellent coating film.

<Method for producing aqueous dispersion>
The aqueous dispersion of the present invention is produced through the following steps.
(A) A step of melt-kneading an olefin-based thermoplastic resin (A), an acid-modified polyolefin (B), and an α-olefin sulfonate (C) to obtain a melt-kneaded product.
(B) A step of injecting water into the melt-kneaded product while performing melt-kneading to obtain an aqueous dispersion in which the solid content is dispersed in water.
(C) A step of diluting the aqueous dispersion with water to obtain an aqueous dispersion.

(A) Process:
The olefinic thermoplastic resin (A) is a polymer having a structural unit derived from α-olefin, and usually lacks dispersibility in water. As the α-olefin, ethylene, propylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-hexene, 1-octene, Examples include 1-decene and 1-dodecene.

  Examples of the olefinic thermoplastic resin (A) include polyolefins, copolymers of ethylene and vinyl compounds, copolymers of α-olefins and conjugated dienes or nonconjugated dienes, and the like.

Examples of the polyolefin include an α-olefin homopolymer and an α-olefin random or block copolymer.
Examples of the α-olefin homopolymer include low density polyethylene, high density polyethylene, polypropylene, poly-1-butene, poly-3-methyl-1-butene, poly-4-methyl-1-pentene, poly-3-methyl- 1-pentene and the like can be mentioned.
Examples of the α-olefin random or block copolymer include an ethylene-propylene copolymer, a propylene-butene-ethylene terpolymer, and a polypropylene having a polyethylene portion usually called “block PP”.

  Examples of the copolymer of ethylene and a vinyl compound include an ethylene-vinyl acetate copolymer, an ethylene-vinyl alcohol copolymer, and an ethylene- (meth) acrylic acid copolymer.

  Copolymers of α-olefin and conjugated diene or non-conjugated diene include ethylene-butadiene copolymer, ethylene-ethylidene norbornene copolymer, ethylene-propylene-butadiene terpolymer, ethylene-propylene-dicyclo Examples thereof include a pentadiene terpolymer, an ethylene-propylene-ethylidene norbornene terpolymer, and an ethylene-propylene-1,5-hexadiene terpolymer.

  The olefinic thermoplastic resin (A) may be used alone or in combination of two or more. As an olefin type thermoplastic resin (A), the homopolymer or copolymer of an alpha olefin is preferable.

Examples of the acid-modified polyolefin (B) include the following.
(B-1) A graft polymer obtained by graft polymerization of an unsaturated carboxylic acid or an unsaturated carboxylic acid ester to the olefinic thermoplastic resin (A).
(B-2) A random copolymer of the α-olefin, an unsaturated carboxylic acid or an unsaturated carboxylic acid ester, and, if necessary, the vinyl compound.

Examples of the unsaturated carboxylic acid include (meth) acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid, maleic anhydride, citraconic anhydride and the like.
Examples of the unsaturated carboxylic acid ester include monoalkyl esters of the unsaturated carboxylic acids and dialkyl esters of the unsaturated carboxylic acids. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group.

As for the average molecular weight by the viscosity method of acid-modified polyolefin (B), 1000-15000 are preferable.
The acid value of the acid-modified polyolefin (B) is preferably 10 to 100 mgKOH / g, and more preferably 30 to 80 mgKOH / g.

  The amount of the acid-modified polyolefin (B) is 1 to 20 parts by mass with respect to 100 parts by mass of the olefin-based thermoplastic resin (A), and preferably 5 to 15 parts by mass. When the amount of the acid-modified polyolefin (B) is within this range, the olefin-based thermoplastic resin (A) can be sufficiently dispersed, and the storage stability of the resulting aqueous dispersion becomes good.

  The α-olefin sulfonate (C) is an α-olefin mixture having 12 to 20 carbon atoms (a mixture of isomers such as 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicocene). ), And after reacting with anhydrous sulfuric acid, it is obtained by hydrolysis and is a mixture of various alkenyl sulfonates, 2-hydroxyalkane sulfonates, 3-hydroxyalkane sulfonates, disulfonates, etc. is there.

  The quantity of (alpha) -olefin sulfonate (C) is 1-15 mass parts with respect to 100 mass parts of olefin type thermoplastic resins (A), and 2-8 mass parts is preferable. If the amount of α-olefin sulfonate (C) is 1 part by mass or more, an aqueous dispersion can be obtained. When the amount of the α-olefin sulfonate (C) is 2 parts by mass or more, the storage stability of the obtained aqueous dispersion becomes good, and the water resistance of the obtained coating film becomes good. When the amount of the α-olefin sulfonate (C) is 15 parts by mass or less, the water resistance of the obtained coating film is good. When the amount of the α-olefin sulfonate (C) is 8 parts by mass or less, the water resistance of the obtained coating film is further improved.

As an apparatus used for melt kneading, a pressure kneader is used in a batch system, and a twin screw extruder is used in a continuous system.
The melt kneading temperature is realistically 140 to 250 ° C., but higher temperatures are possible as long as the confidentiality of the apparatus can withstand the water vapor pressure that rises rapidly as the temperature increases.

(B) Process:
When liquid water is poured into the melt-kneaded product and the melt-kneading is continued, so-called phase inversion occurs and an aqueous dispersion in which the solid content is dispersed in water is obtained.
The amount of water is 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass with respect to 100 parts by mass of the olefinic thermoplastic resin (A). If the amount of water is within this range, phase inversion occurs and an aqueous dispersion in a good dispersion state is obtained.

Water is injected under a pressure higher than the saturated vapor pressure of water at the melt kneading temperature. By injecting water under the pressure, it is possible to inject water without boiling water. For example, when melt-kneading is performed at 200 ° C., water is injected under a pressure higher than the saturated vapor pressure of water (15.5 MPa) at 200 ° C.
As an apparatus used for melt kneading, the same apparatus as in step (a) may be used.
The temperature of melt kneading should just be the same temperature as the (a) process.

(C) Process:
The aqueous dispersion obtained in the step (b) has a solid content dispersed in water, but is usually solid because of a small amount of water. By diluting the aqueous dispersion with water, a liquid aqueous dispersion having a solid content dispersed in water can be obtained.
The solid content concentration of the obtained aqueous dispersion is preferably 30 to 60% by mass in the aqueous dispersion (100% by mass).

<Aqueous dispersion>
The solid content concentration of the diluted aqueous dispersion produced by the production method of the present invention is preferably 30 to 60% by mass in the aqueous dispersion (100% by mass).
When the solid content concentration of the aqueous dispersion is 30 mass or more, it becomes difficult to separate when left standing, and the storage stability becomes good. When the solid content concentration of the aqueous dispersion is 60% by mass or less, an appropriate viscosity is obtained, and a uniform aqueous dispersion is obtained.

  The aqueous dispersion of the present invention may contain a dispersant, a stabilizer, a wetting agent, a thickener, a foaming agent, an antifoaming agent, a coagulant, a gelling agent, an antiaging agent, a softening agent, a plasticizer, if necessary. Well-known auxiliary materials, such as an agent, a filler, a coloring agent, a fragrance | flavor, an anti-tack agent, and a mold release agent, may be included.

Since the α-olefin sulfonate (C) is used as the surfactant in the aqueous dispersion of the present invention described above and the method for producing the same, there are few unemulsified products, storage stability and chemical stability. It is possible to form a coating film having excellent properties and water resistance.
Further, in the aqueous dispersion of the present invention and the method for producing the same, the olefinic thermoplastic resin (A) is dispersed in water by a so-called post-emulsification method, so that the olefinic thermoplastic as in the emulsion polymerization method. The kind of resin is not limited.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example.
(Olefin-based thermoplastic resin (A))
(A-1): Ethylene-propylene-diene terpolymer (EPDM) (manufactured by Mitsui Chemicals, “Tuffmer TP-3180”, ethylene unit content 70 mass%, Mooney viscosity 9 (ML _{1 + 4} , 125 ° C)).
(A-2): Propylene-butene-ethylene terpolymer (Degussa, “VESTLAST 891”, 190 ° C. viscosity 80000-150000 mPa · s).
(A-3): Ethylene-vinyl acetate copolymer (Mitsui DuPont, “EVAFLEX 210”, MFR (190 ° C.) 400 g / 10 min, vinyl acetate unit content 28 mass%).

(Acid-modified polyolefin (B))
(B-1): Acid-modified polyethylene wax (Mitsui Chemicals, "Mitsui High Wax 2203A", acid value 30 mg / g, average molecular weight 2700 by viscosity method).

(Α-olefin sulfonate (C))
(C-1): α-olefin sulfonic acid sodium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Neogen AO-90”).
(C-2): Sodium α-olefin sulfonate (manufactured by Lion Corporation, “Lipolane PB-800”).

(Other surfactants)
(C′-3): Sodium dodecyl benzene sulfonate (manufactured by Kao Corporation, “Neopelex No. 6”).

[Example 1]
(A-1) 100 parts by mass, (B-1) 4 parts by mass, and (C-1) 4 parts by mass are each fed to a twin screw extruder via a quantitative feeder, melt-kneaded at 200 ° C., The amount was 108 parts by mass of the melt-kneaded product.

Subsequently, 5 parts by mass of pure water was injected into the melt-kneaded product at 1.8 MPa from an injection nozzle installed in the middle part of the twin screw extruder while being melt-kneaded at 200 ° C. Subsequently, the mixture was melt-kneaded at 200 ° C. to obtain an aqueous dispersion by phase inversion.
The aqueous dispersion was led to a jacketed stack kick mixer and cooled to below the boiling point of water. The solid aqueous dispersion taken out from the stack kick mixer was poured into warm water at 90 ° C. and continuously dispersed to obtain an aqueous dispersion having a solid content of 40% by mass. This aqueous dispersion was evaluated as follows. The results are shown in Table 1.

(Solid content concentration)
Solid content concentration is the mass% of the non-volatile component contained in an aqueous dispersion liquid, and the measurement was implemented at 135 degreeC with the halogen moisture meter by a METTLER TOLEDO company.

(Amount of non-emulsified product)
The amount of the non-emulsified product is obtained by filtering the aqueous dispersion (solid content mass X) with a # 100 mesh stainless steel wire mesh, washing the residue on the mesh with water and drying, and measuring the solid content mass Y of the residue. Determined by
Un-emulsified amount (% by mass) = Y / X × 100.

(Storage stability)
After the aqueous dispersion was stored at 50 ° C. for 1 month in a sealed glass container, the appearance of the aqueous dispersion was observed and evaluated according to the following criteria.
○: No change in appearance compared to before storage.
Δ: Changes in appearance such as formation of a thin film of aggregates on the surface, and nothing remains on the mesh after filtration and washing with a # 100 mesh stainless steel wire mesh.
X: Appearance changes such as the formation of a thin film of aggregates on the surface, and the aggregates remain on the mesh after being filtered and washed with a # 100 mesh stainless steel wire mesh.

(Chemical stability)
A 5 mass% calcium chloride solution was gently added dropwise to 20 g of the solid content of the aqueous dispersion, and then the aqueous dispersion was observed and evaluated according to the following criteria.
A: Even if 1 g or more of 5 mass% calcium chloride solution is dropped, no aggregate is generated.
(Triangle | delta): While a 5 mass% calcium chloride solution is dripped to 1g, an aggregate will generate | occur | produce.
X: An agglomerate is immediately generated around the calcium chloride solution just by dropping one drop of the 5 mass% calcium chloride solution.

(water resistant)
The aqueous dispersion was applied to a glass plate so that the film thickness became 10 μm, and dried at 80 ° C. for 30 minutes with a hot air dryer. The obtained coated plate was allowed to stand at room temperature for one day and then immersed in warm water at 40 ° C. for 10 days. The coated plate was observed and evaluated according to the following criteria.
○: There is no change in the appearance of the painted plate.
Δ: Roughness is felt on the surface of the painted plate.
X: There is a clear change such as swelling on the surface of the coated plate.

[Examples 2 and 3]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 1 except that the amount of (B-1) was changed to the amount shown in Table 1. The results are shown in Table 1.

[Examples 4 and 5]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 2 except that the amount of pure water to be injected was changed to the amount shown in Table 1. The results are shown in Table 1.

Example 6
An aqueous dispersion was obtained in the same manner as in Example 2 except that the amount of warm water in which the aqueous dispersion was dispersed was adjusted to 57.5 parts by mass so that the solid content concentration of the aqueous dispersion was 65% by mass. And evaluated. The results are shown in Table 2.

Example 7
An aqueous dispersion was obtained and evaluated in the same manner as in Example 2 except that (C-1) was changed to (C-2). The results are shown in Table 2.

Example 8
(A-1) is changed to (A-2), (B-1), (C-1) and the amount of pure water to be injected are changed to the amounts shown in Table 2, and the melt-kneading temperature is set to 190 ° C. The pressure at the time of pouring pure water was changed to 1.5 MPa, and the amount of warm water in which the aqueous dispersion was dispersed was adjusted to 336 parts by mass so that the solid content concentration of the aqueous dispersion was 25% by mass. Except for the above, an aqueous dispersion was obtained and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 9
An aqueous dispersion was obtained and evaluated in the same manner as in Example 8 except that the amount of warm water in which the aqueous dispersion was dispersed was adjusted to 135 parts by mass so that the solid concentration of the aqueous dispersion was 45% by mass. Went. The results are shown in Table 2.

Example 10
An aqueous dispersion was obtained and evaluated in the same manner as in Example 9 except that the amounts of (B-1) and (C-1) and the pure water to be injected were changed to the amounts shown in Table 2. The results are shown in Table 2.

Example 11
(A-1) is changed to (A-3), (B-1) and the amount of pure water to be injected are changed to the amounts shown in Table 3, the melt-kneading temperature is changed to 190 ° C., An aqueous dispersion was obtained and evaluated in the same manner as in Example 1 except that the pressure at the time of pouring was changed to 1.5 MPa. The results are shown in Table 3.

Example 12
The aqueous dispersion was changed in the same manner as in Example 11 except that (C-1) was changed to (C-2) and (C-2) and the amount of pure water to be injected were changed to the amounts shown in Table 3. Obtained and evaluated. The results are shown in Table 3.

Example 13
An aqueous dispersion was obtained and evaluated in the same manner as in Example 11 except that the amount of pure water to be injected was changed to the amount shown in Table 3. The results are shown in Table 3.

Example 14
An aqueous dispersion was obtained and evaluated in the same manner as in Example 11 except that (C-1) and the amount of pure water to be injected were changed to the amounts shown in Table 3. The results are shown in Table 3.

[Comparative Example 1]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 2 except that (C-1) was changed to (C′-3). The results are shown in Table 4. There were many unemulsified products, and the storage stability, chemical stability, and water resistance of the coating film were inferior.

[Comparative Example 2]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 2 except that the amount of (B-1) was changed to the amount shown in Table 4 (25 parts by mass). The results are shown in Table 4. There were many unemulsified products, and the storage stability, chemical stability, and water resistance of the coating film were inferior.

[Comparative Example 3]
An aqueous dispersion was obtained in the same manner as in Example 2 except that the amount of (B-1) was changed to the amount shown in Table 4 (0.5 part by mass), but no aqueous dispersion was obtained. It was.

[Comparative Example 4]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 2 except that the amount of (C-1) was changed to the amount shown in Table 4 (20 parts by mass). The results are shown in Table 4. There were many unemulsified products, and the storage stability, chemical stability, and water resistance of the coating film were inferior.

[Comparative Example 5]
An aqueous dispersion was obtained in the same manner as in Example 2 except that the amount of (C-1) was changed to the amount shown in Table 5 (0.5 part by mass), but no aqueous dispersion was obtained. It was.

[Comparative Example 6]
An aqueous dispersion was obtained in the same manner as in Example 2 except that the amount of pure water to be injected was changed to the amount shown in Table 5 (33 parts by mass), but no aqueous dispersion was obtained.

[Comparative Example 7]
An aqueous dispersion was obtained in the same manner as in Example 2 except that the amount of pure water to be injected was changed to the amount shown in Table 5 (0.5 part by mass), but no aqueous dispersion was obtained. .

[Comparative Example 8]
An aqueous dispersion was obtained and evaluated in the same manner as in Example 9 except that (C-1) was changed to (C′-3). The results are shown in Table 5. There were many unemulsified products, and the storage stability, chemical stability, and water resistance of the coating film were inferior.

The aqueous dispersion of the present invention is useful as an adhesive, a paint or the like using an olefinic thermoplastic resin.

Claims (3)

1 to 20 parts by mass of maleic anhydride-modified polyolefin (B) and 100 parts by mass of olefinic thermoplastic resin (A) with respect to 100 parts by mass of olefinic thermoplastic resin (A) and olefinic thermoplastic resin (A). A step of melt-kneading 1 to 15 parts by mass of α-olefin sulfonate (C) with respect to parts to obtain a melt-kneaded product,
While performing melt kneading, 1 to 30 parts by mass of water is added to the melt-kneaded product under a pressure higher than the saturated vapor pressure of water at the melt kneading temperature with respect to 100 parts by mass of the olefinic thermoplastic resin (A). Injecting and obtaining an aqueous dispersion in which the solid content is dispersed in water;
And a step of diluting the aqueous dispersion with water to obtain an aqueous dispersion.   An aqueous dispersion obtained by the method for producing an aqueous dispersion according to claim 1. The aqueous dispersion according to claim 2, wherein the solid content concentration is 30 to 60% by mass.