JPH0138409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the production of aqueous dispersion compositions. More specifically, the present invention relates to a method for producing a novel aqueous dispersion composition that can be advantageously used for thermal adhesives, coating agents, surface treatment agents, etc. for paper, metals, plastics, etc. [Prior Art] Aqueous dispersion compositions of modified copolymers of ethylene, α,β-unsaturated carboxylic acids, and α,β-unsaturated carboxylic acid metal salts are disclosed in, for example, JP-A-57-137339. However, the grafting efficiency was low and the stability of the aqueous dispersion was poor. In this proposal, an anionic surfactant is used as a dispersion aid, but
Such surfactants can often be a hindrance in the use of dispersion compositions of this type. For example, it is well known that they adversely affect the adhesion, water resistance, etc. of coating films obtained from dispersion compositions. The same proposal also proposes an aqueous dispersion that does not contain such a surfactant. However, in this case, since acrylic acid, which is hydrophilic but also acidic, is used as the modifying monomer, it may be difficult to stabilize the reaction system during emulsion modification polymerization, and in some cases, the emulsion dispersion may may cause aggregation. The same publication also proposes a dispersion composition that uses an ionomer with a reduced ethylene content as a raw material and does not contain a surfactant, but as the ethylene content decreases, the rigidity of the ionomer decreases. In the use of the dispersion composition, it is not necessarily preferable in terms of physical properties. [Problems to be solved by the invention] The present invention solves the problems of the prior art described above,
The object of the present invention is to propose a method for producing a novel aqueous dispersion composition that provides excellent physical properties and has fewer difficulties during production. [Summary of the invention] The present invention provides ethylene (a), α,
A group consisting of a copolymer (A) consisting of a β-unsaturated carboxylic acid (b) and an α,β-unsaturated carboxylic acid metal salt (c), a styrenic hydrocarbon and an α,β-unsaturated carboxylic acid ester When graft polymerizing the monomer (B) selected from the above (b) and (c) as the copolymer (A),
(c)
The gist of this invention is a method for producing an aqueous dispersion composition, characterized in that graft polymerization is carried out without using a surfactant, using a copolymer having a content molar ratio of (b) in the range of 1.2 to 1.8. . [Ionomer (A)] The ionomer (A) used in the present invention has a specific component content. That is, ethylene
(a), an α,β-unsaturated carboxylic acid (b) and an α,β-unsaturated carboxylic acid metal salt (c), and the total content of (b) and (c) is 4 to 10 mol%. within a range, preferably within a range of 4.5 to 6 mol%, and the molar ratio of (c) to (b) is within a range of 1.2 to 1.8;
Preferably it is in the range of 1.3 to 1.5. If the total content of (b) and (c) is outside the above-mentioned essential range, that is, 4 mol% or less, a uniform and stable dispersion cannot be obtained without using a surfactant.
If the amount exceeds mol%, the modified resin loses its rigidity, and when a dispersion of the modified product is used in an adhesive or a heat sealing material, adhesive strength, water resistance, chemical resistance, etc. are significantly reduced. If the molar ratio of (c) to (b) is outside the above-mentioned essential range, it will be difficult to obtain a uniform and stable aqueous dispersion of the emulsified modified product without using a surfactant, and the graft efficiency decreases. Examples of the α,β-unsaturated carboxylic acid (b) which is a component of the ionomer (A) include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, etc. metal salt
Examples of (c) include sodium, potassium, and lithium salts of the above acids. A particularly preferred component (b) is methacrylic acid, and a particularly preferred component (c) is methacrylic acid sodium salt. The above (a), (b) and
In addition to component (c), esters of the α,β-unsaturated carboxylic acids, such as linear or branched lower alkyl esters of acrylic acid or methacrylic acid, ammonium salts of the α,β-unsaturated carboxylic acids, and acetic acid. Vinyl esters such as vinyl, pinyl alcohol, etc. may be contained, but the content of these in a stable aqueous dispersion should be usually less than half of the molar content of the α,β-unsaturated carboxylic acid metal salt (c). preferred for obtaining. In addition, in calculating the above-mentioned essential ranges of components (a), (b), and (c), the content of the other components shall be included in component (c). [Monomer (B)] Monomers to be graft-polymerized to the above ionomer (A) in an aqueous dispersion state include, for example, styrene hydrocarbons such as styrene, α-methylstyrene, and vinyltoluene, methyl (meth)acrylate,
(meth)ethyl acrylate, (meth)propyl acrylate, (meth)acrylate n-butyl, (meth)acrylate
sec-butyl acrylate, (meth)acrylic acid iso
Examples include (meth)acrylic acid alkyl esters such as -butyl and 2-ethylhexyl (meth)acrylate, among which styrene, n-butyl acrylate, methyl methacrylate and the like are preferred. These monomers are styrenic hydrocarbons or α, β
-Unsaturated carboxylic acid esters may be used alone or in combination. monomer
The amount of (B) used is based on 100 parts by weight of ionomer (A).
Usually 10 to 2000, preferably 50 to 1000. As mentioned above, the aqueous dispersion composition of the present invention containing a graft-modified ionomer can be obtained without using a surfactant or a hydrophilic monomer, but within a range that does not impair the stability of the dispersion. Hydrophilic monomers such as (meth)acrylic acid, acrylonitrile, and acrylamide may be used together with styrenic hydrocarbons or α,β-unsaturated carboxylic acid esters. However, for the reasons mentioned above, it is more preferable not to use it. [Production] According to the present invention, the aqueous dispersion composition can be obtained by emulsion graft polymerization of the monomer (B) in an aqueous dispersion state of the ionomer (A). Aqueous dispersions of ionomers (A) are disclosed in, for example, JP-A-51-
It can be obtained by the method disclosed in No. 62890.
Furthermore, when performing grafting, a persulfate or an organic peroxide is usually used as a polymerization initiator, but graft polymerization is performed without using a surfactant. Examples of these initiators include ammonium persulfate and benzoyl peroxide-dimethylaniline. Specific examples of the manufacturing method are as shown in Examples. [Aqueous dispersion composition] The aqueous dispersion composition obtained in the present invention contains a homo(co)polymer of monomer (B) in addition to a grafted product in which monomer (B) is grafted onto ionomer (A). However, it is usually not necessary to remove this when used for each purpose. The total concentration (solid content concentration) of both the graft material and the homo (co)polymer in the composition obtained according to the present invention is usually 10 to 60% by weight, preferably 20 to 50% by weight. In addition to the above-mentioned components, the composition obtained by the present invention may include various emulsifiers, thickeners, pigments, PH regulators, binders, etc., depending on the purpose and within the range that does not impair the effects of the present invention.
It may contain a dispersing aid, a film-forming aid, a lubricant, an antiblocking agent, a coloring agent, and the like. [Effects] The aqueous dispersion composition obtained in the present invention has high grafting efficiency because it contains a grafted product in which a monomer (B) is grafted onto a specific ionomer (A), and stable dispersion can be achieved without using a surfactant. It can maintain its condition and exhibits the following excellent physical properties in various applications. [Applications] The aqueous dispersion composition obtained in the present invention can be used, for example, in the applications described in JP-A-57-137339. That is, it can be applied directly to paper, metals, and plastics to provide a thermal adhesive with excellent adhesive strength. It is also possible to thermally bond the coating films formed by this coating or the coating film and other paper, metal, or plastic by heat sealing. For example, a vinylidene chloride resin layer is coated on a biaxially oriented polypropylene film, polyester film, nylon film, etc. to impart gas barrier properties, and the composition according to the present invention is applied as a heat-sealing layer on the vinylidene chloride resin layer. Can be coated. Further, an anchor coating agent may be used for the purpose of further improving the adhesion between these films and the coating film made of the composition of the present invention. In this case, the aforementioned film may be previously coated with an anchor coat, and the composition of the present invention may be applied thereon to form a heat-sealable coating. The anchor coating agent in this case varies depending on the type of film to be coated, but polyethyleneimine, polyester, polyurethane, polyether, organic titanium, polybutadiene, and the like can be used. The base materials used for coating the composition obtained in the present invention generally include papers such as kraft paper, high-quality paper, and coated paper, metal foils and sheets made of aluminum and iron, and sheets such as aluminum and chrome. Examples of plastics include polyethylene, ethylene vinyl acetate copolymer, and ethylene ionomer. Ethylene resins such as, polystyrene AS resins, etc.
Examples include polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, polyester, and nylon, and it goes without saying that these materials can be applied to sheets, films, molded products, foams, and other shapes of all kinds. Naturally, copolymers such as vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer, and mixtures thereof are also included. In addition to the above-mentioned thermal bonding, the composition obtained in the present invention also has the following properties:
It can also be used as a coating agent and surface treatment agent for various materials. The coating film formed from the composition obtained in the present invention has high tensile strength, is flexible, transparent, has excellent thermal adhesion and heat sealing properties, is resistant to blocking, and is water resistant. It also has excellent properties. Hereinafter, the present invention will be specifically explained with reference to Examples. [Example] Example 1 A copolymer of ethylene, methacrylic acid, and its Na salt, which is an aqueous ionomer resin containing 2.2 mol% of methacrylic acid and 3.2 mol% of its Na salt, with a solid content concentration of 25% by weight. A trace amount of potassium persulfate was added as a polymerization initiator to 400 parts by weight of the dispersion, and 100 parts by weight of styrene was added dropwise while heating to 80°C to carry out emulsion polymerization. As a result, a milky white uniform product with a solid content of 40% by weight was obtained. A stable aqueous dispersion was obtained. The polymer obtained by drying this aqueous dispersion is
The ungrafted polystyrene was removed by heating at 75°C for 2 hours in MEK, and the styrene grafting efficiency was found to be 71% based on its weight. When the polymer particles of the obtained aqueous dispersion were observed with an electron microscope, the particles after emulsion polymerization were spherical as before polymerization, but they were uniformly enlarged, and no new particles were observed. It was confirmed that the polymerization of was proceeding inside the ionomer particles, not in the aqueous phase. Examples 2 to 6, Comparative Examples 1 to 3 Table 1 shows the results when aqueous dispersions of ionomer resins having different compositions were subjected to emulsion modification in the same manner as in Example 1 without using a surfactant. 【table】

Claims (1)

[Claims] 1 In an aqueous dispersion state, a styrenic hydrocarbon is added to a copolymer (A) consisting of ethylene (a), an α,β-unsaturated carboxylic acid (b), and an α,β-unsaturated carboxylic acid metal salt (c). When graft polymerizing the monomer (B) selected from the group consisting of An aqueous dispersion composition characterized by carrying out graft polymerization without using a surfactant using a copolymer in which the molar ratio of (c) to (b) is in the range of 1.2 to 1.8. How things are manufactured.