JPS5916574B2 - Dispersion manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified polyolefin dispersion.

Since polyolefins such as polyethylene and polypropylene are typical non-polar substances, it is known that their adhesion to metals and other films is extremely low.

Various proposals have been made to improve the adhesive properties of polyolefins. For example, (1) chemical treatments such as the sulfuric acid monochromate method are effective if heated, but wet methods This results in poor workability, and the use of acid causes corrosion to the reactor and other parts. Therefore, this method is one that is only rarely implemented today for basic research or for comparison with other surface treatment methods. Industrially, (2) a chemical treatment in which an unsaturated carboxylic acid is grafted onto a polyolefin; further subdivided into (a) a polyolefin is heated and dissolved in a hydrocarbon solvent, and an unsaturated carboxylic acid is grafted in the presence of a radical catalyst. (b)
) A method in which a finely ground polyolefin is charged in water containing a surfactant, made into a suspended state, and an unsaturated carboxylic acid is grafted in the presence of a radical catalyst, and (c) a method in which a polyolefin, a radical initiator, and an unsaturated carboxylic acid are grafted together. A method of pre-stirring with a pencil mixer, charging it into an extruder, and grafting using a mechanochemical method; (3) a surface treatment method of creating polar groups by oxidizing the surface of polyolefin with air, oxygen or ozone; 4) Flame treatment in which polyethylene is brought into direct contact with city gas or carbonized gas flame, (5) Discharge treatment by corona discharge, (6) Surface graft treatment in which polar substances are grafted onto the polyolefin surface to improve adhesion, and When subdivided, (a) 60Co as a radiation source
(b) methyl methacrylate, and (b) methyl methacrylate. , a method of grafting maleic anhydride onto a polyolefin using a radical catalyst, (7) a heat treatment in which polyethylene powder or J5 sheet is placed on a metal surface and heated to 200 to 300°C, and (8) a method of grafting an inorganic filler onto a polyolefin. There is also a blending process that mixes the A polyolefin having good adhesive properties has been obtained by the above method or a combination thereof.

However, with these methods, in the food-related field,
It has the following drawbacks: That is, in the chemical treatment (1), an acid, in the chemical treatment (2), an unreacted unsaturated carboxylic acid, a radical catalyst, and a surfactant, and in the surface grafting treatment (6), an unreacted monomer, a radical catalyst, , (8)
In the blending process, the inorganic filler remains in the resin, and the resin needs to be washed, and the washing process takes a long time. Also, these residues are often not removed even after prolonged cleaning. In fields other than food-related, it has the following drawbacks. In the chemical treatment (1), a large amount of water must be used to remove acids and the like from the resin, and wastewater treatment is necessary because the wastewater contains chromium ions. Since the chemical treatment (2) uses solvents, monomers, and radical catalysts, there are risks of fire and toxicity during the work. Furthermore, in the method (2)-(b) using a surfactant, the adhesion may not be sufficiently improved because of the surfactant. Treatments (3), (4) and (5) do not provide sufficient adhesion. In the surface grafting treatment using radiation (6), the radiation irradiation equipment is expensive and dangerous. The applicant of this patent has already filed a patent application (Japanese Patent Application No. 138694/1983) for an inner coating composition for cans, which is characterized by dispersing polyolefin into which a polar group has been introduced in a solid state in a solvent. ing.

As a result of further research into polyolefin paints that do not cause food hygiene problems due to residual monomers and have excellent adhesion to metals, etc., the present invention developed an untreated polyolefin paint that has not introduced any polar groups into a hydrocarbon paint. Solvent 1
A modified polyolefin dispersion is obtained by heating and dissolving a polyolefin in a mixed solvent of a hydrocarbon solvent and a non-hydrocarbon solvent, irradiating the polyolefin with ultraviolet rays, and cooling the dispersion. This was done based on the knowledge that it has excellent adhesion and poses no food hygiene problems. The modified polyolefin dispersion according to the present invention can be applied as it is as an inner coating composition for X cans, an anchor coating agent, other coatings, or as an adhesive, or can be applied by a conventional spray drying method. The solvent and the modified polyolefin are separated, and the resulting finely powdered modified polyolefin can be applied to powder coatings, hot melt materials, and others.

The polyolefin used in the present invention is not particularly limited, but desirably, when used in food-related fields, a polyolefin containing no additives such as antioxidants is appropriately selected.

When modified polyolefin containing additives is used in food-related fields, the additives may migrate into the food. The hydrocarbon solvent and non-hydrocarbon organic solvent in the present invention are not particularly limited, but the solvent may be appropriately selected depending on the intended use.

Solvents used in the present invention include hydrocarbon solvents with relatively low boiling points such as benzene, hexane, heptane, and mineral spirits, aromatic hydrocarbons such as toluene and xylene, and fatty acids such as isooctanenonane and decane. group hydrocarbons, methylzig.

−． Alicyclic hydrocarbons such as xane, ethylcyclohexane, decahydronaphthalene, or relatively high-boiling hydrocarbons such as solvent naphtha may be used depending on the application. Other solvents used with the above hydrocarbons include alcohol solvents such as ethanol, methanol, propanol, isopropanol, butanol, octanol, cetyl alcohol, and diacetone alcohol, and ester solvents such as ethyl acetate, butyl acetate, and cellosolve acetate. , methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isoborone, and other ketone solvents; ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and other ethers; halogenated hydrocarbon solvents such as carbon tetrachloride and trichloroethylene.

If only a hydrocarbon solvent, especially a hydrocarbon solvent with a boiling point higher than the melting point of the polar group-containing polyolefin, is used alone, it may clog the gun during spraying, resulting in a system that is difficult to coat.

In addition, when using only non-hydrocarbon solvents, a whitening phenomenon due to resin precipitation is observed after coating or in the early stages of baking, due to resin precipitation before the resin particles harden, and if baking is performed with this whitening phenomenon still occurring, a uniform and smooth coating will be obtained. It may not be possible to form a film. Therefore, when used as an inner surface coating for can manufacturing, the ratio of hydrocarbon solvent to non-hydrocarbon organic solvent is approximately 100/0 to 70/30 (by weight), preferably 1.
It is preferable to appropriately select from about 00/0 to 90/10 depending on the type of each solvent and polar group-containing polyolefin. In the practice of the present invention, the weight ratio of polyolefin and solvent is 1/100 to 30/1001, preferably 5/1.
It is about 100 to 20/100.

In the practice of the present invention, a wax having a melting point of 70 to 120°C, preferably 90 to 120°C is added to the polyolefin.
It is effective to use about 10 parts by weight of 051 to 10 parts by weight because the rate of occurrence of pinholes in the formed coating film is further reduced. The method of irradiating ultraviolet rays is not particularly limited, but for example, a part of the side surface of the reactor may be made of quartz glass and ultraviolet rays may be irradiated from the side, or a portion of the upper part of the reactor may be made of quartz and ultraviolet rays may be irradiated from the top.

The adhesiveness of modified polyolefin has a correlation with the amount of ultraviolet irradiation, and when the amount of ultraviolet irradiation is large, the irradiation time and distance from the solution surface should be selected appropriately. The irradiation atmosphere is not particularly limited and may be air, oxygen, or nitrogen. The polyolefins modified according to the invention exhibit good adhesion to metals such as tinplate and aluminum, polyolefins, and plastics such as epoxy resins.

In addition, it is manufactured based on polyolefin, and has excellent processability and
General properties such as strength and chemical resistance completely retain the properties of the base polyolefin. Furthermore, since no components other than polyolefin and solvent are used, there is no toxicity after the solvent evaporates, and it is safe from a food hygiene perspective. Further, the volatilized solvent can be recovered and reused. Hereinafter, the present invention will be specifically explained with reference to Examples.

Example "Central part" refers to parts by weight. Example 1 Low density polyethylene (F227O manufactured by Asahi Tau Co., Ltd., melt index 7, softening point approximately 110°C)
20 parts of xylene and 80 parts of xylene are placed in a reaction vessel with quartz glass on top, and heated to 85°C while stirring to completely dissolve.

Stirring is performed while irradiating with a 2KW ultraviolet lamp through the quartz glass at the top. The distance between the liquid level and the lamp was 20 cm, and irradiation was performed for 10 hours. 100 in dilution can
A weight part of cold xylene was charged, and a xylene solution of modified polyethylene was added dropwise with stirring to obtain a milky white dispersion with an average particle size of 15 μm. 100 parts by weight of isopropanol was added to this to form a paint. The obtained dispersion is
It is stable not only immediately after preparation, but also after 3 months of use, and does not clog the gun during painting. Comparative Example 1 Adhesion was tested in the same manner as in Example 1 except that no ultraviolet irradiation was performed, and no practical strength was shown at all.

Example 2 Low density polyethylene (Mitsui Polychemical Co., Ltd. Mirason 68 melt index 23, softening point 110°C) 20
1 part, 70 parts of ethylcyclohexane, and 10 parts of methyl isobutyl ketone are placed in a reaction vessel with a quartz glass base, and heated to 100°C while stirring to completely dissolve.

Stirring is performed while irradiating with a 2KW ultraviolet lamp through the quartz glass at the top.

Is the distance between the liquid level and the lamp 20? The irradiation was carried out for 12 hours. A dilution can was charged with 100 parts by weight of cold ethylcyclohexane, and a solution of modified polyethylene in ethylcyclohexane was added dropwise while stirring to obtain a milky white dispersion with an average particle size of about 15 μm. To this was added 100 parts by weight of methyl isobutyl ketone to form a paint. This paint is stable not only immediately after preparation, but also after 3 months of use, and does not clog the gun during painting. Example 3 A modified polyolefin produced in Example 1 using toluene instead of xylene and methyl ethyl ketone instead of isopropanol was spray-dried to obtain fine powder.

This was applied to an aluminum plate preheated to 160° C. by electrostatic coating to a thickness of 30 μm. The adhesion according to the cross-cut test method was 100/100, and the bending resistance and boiling resistance for 30 minutes were good. Example 4 Polypropylene (Mitsui Polychemical Co., Ltd. F63O,
10 parts (melt index: 9.01, softening point: 145°C) and 90 parts of Solbetsuso 1150 (aromatic petroleum solvent, trade name manufactured by Shell Chemical Co., Ltd.) were placed in a reaction pot with quartz glass on top, and heated to 120°C while stirring. Dissolves completely when heated.

Stirring is performed while irradiating with a 2KW ultraviolet lamp through the quartz glass at the top. Is the distance between the liquid level and the lamp 20? The irradiation was carried out for 10 hours. A dilution can was charged with 50 parts by weight of cold cellosolve acetate, and a solution of modified polypropylene was added dropwise while stirring to obtain a milky white dispersion with an average particle size of 15 μm. This dispersion was coated with a roll coater.
It was uniformly applied on an aluminum plate at a ratio of 0 cd/100 cd and baked at 200°C for 5 minutes.

As a result of the resistance test within the obtained coating, the smoothness was good as a result of visual inspection, and the adhesion was 100/10 by the goblin test.
0, and the bending resistance and retort resistance were good. It was sufficiently practical for use in retort food. Example 5 A paint obtained by stirring 20 parts of the dispersion produced in Example 1 and 80 parts of an epoxy phenol paint was coated with a roll coater at 70 TIV! /100Cd was uniformly applied on a tin plate and baked at 180°C for 5 minutes.

Claims (1)

[Claims] 1 Polyolefin is heated and dissolved in one or more hydrocarbon solvents, or a mixed solution of a hydrocarbon solvent and a non-hydrocarbon organic solvent, and then irradiated with ultraviolet rays to modify the polyolefin. A method for producing a modified polyolefin dispersion, which comprises tightening and cooling.