JPH0159298B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous polymer dispersion in which a high molecular compound, so-called a polymer, is dispersed in water using a dispersant. The aqueous polymer dispersion obtained by carrying out the present invention is useful as a coating material for paper, aluminum foil, film, etc., and as an adhesive. polyethylene wax, low density polyethylene,
A method of producing an aqueous polymer dispersion, a so-called emulsion, by dispersing a polymer such as an ethylene/vinyl acetate copolymer in water using a dispersant such as a surfactant or a protective colloid agent is known. For example, an emulsion of polyethylene wax is obtained by adding polyethylene wax heated and melted using a homomixer to hot water in which a large amount of a surfactant has been dissolved under stirring.
In addition, emulsions of low density polyethylene, chlorinated polypropylene, etc. are prepared by first dissolving these polymers using a large amount of organic solvent, and then heating the solution with a protective colloid agent such as polyvinyl alcohol, methylcellulose, or polyvinylpyrrolidone. It is obtained by adding and mixing in water using a homomixer and then removing the organic solvent. However, since the aqueous dispersions obtained by these methods use a large amount of water-soluble surfactants or protective colloids, the resulting films have low mechanical strength or are difficult to coat on hydrophobic materials such as films and aluminum foils. Adhesion to the surface is often insufficient. Furthermore, in the latter method using the aid of an organic solvent, a small amount of the organic solvent remains in the aqueous dispersion, which imposes great restrictions on the use of this aqueous dispersion in the field of food packaging base materials. The present inventors manufactured and studied various dispersants for the purpose of improving the drawbacks of the prior art, and found that
The inventors have discovered that by using a neutralized product of a specific acrylic copolymer, a film with practically sufficient mechanical strength can be obtained without reducing the adhesion to the substrate, and the present invention has been achieved. That is, the present invention uses a specific polymer compound selected from polyolefin thermoplastic resins, waxes, rubbers, and adhesives as component (A). and/or (B) Ingredients [In the formula, R ₁ is H or CH ₃ ; R ₂ is a C ₁ to _{C 4} alkylene group or a hydroxy-substituted alkylene group; R ₃ and R ₄ are H or a C _{1 to 4} alkyl group; R ₅ is C _{1 ~22} alkyl groups, alkenyl groups, cycloalkyl groups, or aralkyl groups; A is O or NH] A copolymer of the above components (A) and (B) is partially or completely neutralized with an acid. The present invention provides a method for producing an aqueous polymer dispersion, characterized in that the neutralized product is dispersed in water at a temperature equal to or higher than the plasticizing temperature of the polymer. In the practice of the present invention, the specific polymer compounds to be dispersed in water include medium density polyethylene, low density polyethylene, ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer and its ester,
Or its salts, so-called crystalline ethylene copolymers mainly composed of ethylene such as ethylene/propylene random copolymers, crystalline propylene mainly composed of propylene such as propylene/hexene copolymers, propylene/butene copolymers, etc. Polyolefin thermoplastic resins with a melting point of 50 to 130℃ such as copolymers; waxes with a melting point of 50 to 130℃ such as polyethylene waxes, low molecular weight polyamides, and ester waxes; polybutylene, polyisobutylene, and ethylene/propylene. Polymer rubber, ethylene
Rubber substances with a Bigard softening point of 50 to 130°C, such as propylene-diene terpolymer rubber; softening points (ring and ball method) of petroleum resins, terpene resins, rosin, etc., of 50 to 130°C
It is selected from 130℃ adhesives. In order to obtain an aqueous dispersion with fine particle sizes, these polymer compounds must be subjected to a load according to JIS K-6760.
2.16Kg, the melt index measured at 190℃ is 1g/10 minutes to 2000g/10 minutes, preferably 2 to 1500
g/10 minutes. Note that the melting point or softening point of the polymer compound is 130℃.
If it exceeds this amount, it becomes difficult to obtain a uniform aqueous dispersion. Next, a partially or completely neutralized product of the acrylic copolymer that disperses these polymer compounds in water is prepared by combining the following components (A) and (B), and if necessary, other polymerizable monomers. It is produced by partially or completely neutralizing the copolymer obtained by copolymerizing with an acid. (A) Ingredients:

[Formula] and/or teeth

[Formula] (B) Component: [Definitions of R ₁ to R ₅ and A in the formula are the same as above]. The above component (A) includes N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and N,N-dimethylaminoethyl (meth)acrylate. ) acrylamide, N,
N-dimethylamino-2-hydroxypropyl (meth)acrylate, 4-vinylpyridine, 2
- Examples include vinylpyridine. (B) Component acrylic ester (meth)
Methyl acrylate, ethyl (meth)acrylate,
Butyl (meth)acrylate, (meth)acrylic acid 2
-Ethylhexyl, lauryl (meth)acrylate,
(meth)stearyl acrylate, cyclohexyl (meth)acrylate, allyl (meth)acrylate,
Examples include alkyl, alkenyl, cycloalkyl, and aralkyl esters of acrylic acid or methacrylic acid such as benzyl (meth)acrylate.
These may be used alone or in combination of two or more. In addition to these monomers of component (A) and component (B), polymerizable monomers such as vinyl acetate, styrene, vinyl ether, etc. are used as necessary. For component (B), the molar fraction of acrylic ester i of component (B) in the copolymer component is Mi, and the number of carbon atoms in the acrylic ester i is
If Ni is the sum of the products of Mi and Ni (Σ Mi
It is preferable to select and use component (B) in such a proportion that Ni) has a value of 0.5 to 10, preferably 1 to 8. When Σ Mi Ni is less than 0.5 mol, the lipophilicity of the neutralized copolymer is weak, and when it exceeds 10, the lipophilicity is too strong, making it impossible to produce a stable aqueous dispersion in either case. These polymerizable monomers such as component (A) and component (B) are (A)
Component 10-80 mol%, preferably 15-75 mol%, (B)
The components are reacted in a proportion of 90 to 20 mol%, preferably 85 to 25 mol%, in the presence of a polymerization initiator at 0 to 180°C, preferably 40 to 120°C, for 0.5 to 20 hours, preferably 2 to 10 hours. , a copolymer is produced. This polymerization reaction is preferably carried out in the presence of water or a hydrophilic solvent such as ethyl alcohol, isopropyl alcohol, or cellosolve. Examples of the polymerization initiator include azobisisobutyronitrile, t-butylperoxyisobutyrate, 1,1-bis(t-butylperoxy)cyclohexene, and t-butylperoxybenzoate. If the amount of component (A) is less than 10 mol%, the hydrophilicity of the neutralized copolymer obtained will be weak, and if it exceeds 80 mol%, the hydrophilicity of the neutralized product will be too strong, resulting in a stable aqueous polymer dispersion. Unable to produce liquid. If the amount of component (B) is less than 20 mol%, the lipophilicity of the neutralized product of the resulting copolymer will be weak, and if it exceeds 90 mol%, the lipophilicity of the neutralized product will be too strong. It is not possible to obtain a stable aqueous polymer dispersion. Examples of acids that neutralize this copolymer include formic acid, acetic acid, hydrochloric acid, phosphoric acid, and nitric acid. Among these, when using formic acid, acetic acid, and hydrochloric acid, which are volatile at room temperature, the aqueous dispersion When drying to form a film, these acids are liberated from the neutralized product and the hydrophobicity of the dispersant increases, resulting in good water resistance of the film. Neutralization reaction is carried out by combining the copolymer and acid at 20-100°C with a reaction temperature of 0.1~
This is carried out by reacting for 3 hours. In addition, before producing the copolymer, component (A) is neutralized in advance with these acids, and this is polymerized with monomers such as component (B) to produce a neutralized product of the copolymer. It's okay. The amount of acid used for neutralization constitutes the copolymer
It is 10 to 100 mol% of component (A). The partially or completely neutralized product of this copolymer is generally preferably water-soluble, but has a particle size of 0.01 to 5 μm.
It may be a poorly water-soluble solid. This is because the neutralized product itself is a polymer and forms a film. However, if the compatibility between the polymer compound to be dispersed and the neutralized product is poor, the transparency of the film will decrease, so a water-soluble material is preferable. This neutralized product is generally diluted with water and used as a dispersant. The amount used is 2 to 30 parts by weight, preferably 3 to 15 parts by weight in terms of solid content, per 100 parts by weight of the polymer compound to be dispersed.
If the amount is less than 2 parts by weight, a stable aqueous dispersion cannot be produced. If the amount exceeds 30 parts by weight, the mechanical strength of the film will not be suitable for practical use, and the adhesion of the film to substrates such as paper, aluminum foil, and film will decrease. To produce an aqueous dispersion of a polymer compound using this neutralized product as a dispersant, the molten polymer compound is added to water containing the neutralized product, a homomixer,
This is carried out by uniformly stirring using an extruder or the like. The most preferred embodiment is to use a multi-screw extruder having two or more screws in the casing, as disclosed in JP-A No. 56-2149, to supply the polymer compound from the hopper of the extruder, and to heat and melt it. It is produced by kneading and further kneading with an aqueous solution of a neutralized copolymer supplied from at least one liquid supply port provided in the compression zone and/or metering zone of the extruder. Alternatively, a polymer compound and an aqueous solution of a neutralized copolymer are supplied through the hopper of an extruder, heated to a temperature 15°C higher than the plasticization temperature of the polymer compound, and kneaded with a screw. It is also manufactured. Generally, the amount of water used is such that the solid content concentration of the resulting aqueous dispersion is 20 to 65% by weight. In addition to neutralized products of the above-mentioned polymer compounds and copolymers,
Antifoaming agents, viscosity modifiers, anionic surfactants, nonionic surfactants, antioxidants for resins, etc. may also be blended. The aqueous polymer dispersion produced in this way has polymer compound particles with an average particle size of 5μ or less,
The particles having a particle size of 1 μm or less are dispersed in water at 10% by weight or more, preferably 20% by weight or more, and have a viscosity at 25° C. of 10 to 10,000 centipoise, preferably 50 to 5,000 centipoise. This aqueous polymer dispersion can be used as a modifier for paints, adhesives, ink binders, adhesives, and emulsions, depending on the type of polymer compound used. Next, the present invention will be explained in further detail by giving Examples and Comparative Examples. Note that % and parts in the examples are based on weight unless otherwise specified. Example 1 N,N-dimethylaminoethyl methacrylate
62.9 parts (0.4 mol), butyl methacrylate 71 parts (0.5 mol), lauryl methacrylate 25.4 parts (0.1 mol) and 200 parts of isopropyl alcohol were placed in a 4-tub system equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel. Pour into a neck flask, replace with nitrogen gas, and add 2,2'-azobisisobutyronitrile 0.9
was added as a polymerization initiator, and the polymerization reaction was carried out at 80°C for 4 hours. Then 24 parts (0.4 mol) of acetic acid
After neutralizing with water, water was added while distilling off the isopropyl alcohol to finally obtain a viscous aqueous solution of the dispersant (Σ Mi Ni = 3.2) with a solid content of 35%. Ethylene/vinyl acetate copolymer [Ebu Afflex 220 (trade name) manufactured by Mitsui Petrochemical Industries; vinyl acetate content 28%, melting point 74°C, MFR = 150 g/10 minutes]
It was continuously fed from the hopper of a co-rotating intermeshing twin-screw extruder (Ikegai Tekko Co., Ltd. trade name PCM45, triple thread shallow groove type, L/D=30) at a rate of 100 parts/hour. Further, 22.9 parts of the dispersant aqueous solution (8 parts solids) was added to water through the supply port provided in the vent part of the same extruder.
While continuously supplying an aqueous solution diluted with 147.1 parts at a rate of 170 parts/hour under pressure using a gear pump (discharge pressure 3 Kg/cm ² G), the heating temperature (cylinder temperature, the same hereinafter) was 130°C, and the screw Rotation speed 100rpm
The mixture was continuously extruded to obtain a milky white aqueous polymer dispersion (solid content concentration 40%). The average particle size of the dispersed polymer particles in this aqueous polymer dispersion was determined by microscopic observation, and was found to be approximately 1 μm.
It was hot. Furthermore, when this polymer aqueous dispersion was applied to a polyethylene film and dried by heating at 90°C, it showed good adhesion and did not whiten even when the coated film was immersed in water for 1 hour (water resistance was sufficient). Examples 2 to 5, Comparative Example 1 A post-emulsified polymer aqueous dispersion was obtained under the same conditions as in Example 1 except that various polymer compounds shown in Table 1 were used. Table 1 shows the polymer average particle size, stability, and water resistance of the film of this dispersion. Furthermore, the melting point is 136℃ and the melt index is 0.5.
A good resin aqueous dispersion could not be obtained with high density polyethylene having a high density of 100 g/10 min.

[Table] *Softening point Examples 6 to 10, Comparative Examples 2 to 4 Same as Example 1 except that a copolymer was obtained using the monomers shown in Table 2 and this was neutralized with acid (0.4 mol). An aqueous solution of a dispersant was obtained in the same manner. Using this, ethylene and
An aqueous dispersion of vinyl acetate copolymer was prepared. The average particle size and stability of the polymer in the resulting aqueous dispersion and the water resistance of the film were as shown in Table 2. The abbreviations in the table are as follows. DMMA: N,N-dimethylaminoethyl methacrylate EA: Ethyl acrylate BMA: Butyl methacrylate LMA: Lauryl methacrylate SMA: Stearyl methacrylate 4-Vp: 4-vinylpyridine

【table】

Claims (1)

[Scope of Claims] 1. A polyolefin thermoplastic resin with a melting point of 50 to 130°C, a wax with a melting point of 50 to 130°C, a rubber with a Vicard softening point of 50 to 130°C, and a softening point of 50 to 130 according to the ring and ball method. Component (A): 100 parts by weight of a polymer compound selected from adhesives at ℃ and/or (B) Ingredients [In the formula, R ₁ is H or CH ₃ ; R ₂ is a C ₁ to _{C 4} alkylene group or a hydroxy-substituted alkylene group; R ₃ and R ₄ are H or a C _{1 to 4} alkyl group; R ₅ is C _{1 ~~ 22} alkyl, alkenyl, cycloalkyl, or aralkyl groups; A is O or NH. ] Using 2 to 30 parts by weight of a neutralized product obtained by partially or completely neutralizing the copolymer of the above components (A) and (B) with an acid, at a temperature equal to or higher than the plasticizing temperature of the polymer. A method for producing an aqueous polymer dispersion, which comprises dispersing it in water. 2 Component (B) constituting the copolymer is calculated as follows: where the molar fraction of acrylic ester i of component (B) in the copolymer component is Mi, and the number of carbon atoms in the acrylic ester i is Ni. Component (B) is selected and used in a ratio such that the sum of the products of Mi and Ni (ΣMi Ni) is from 0.5 to 10. Production method. 3. The method according to claim 1, wherein the acid is selected from formic acid, acetic acid, and hydrochloric acid.