JPS5928217B2 - Manufacturing method of polyolefin aqueous dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing aqueous dispersions of polyolefins with superior properties.

More particularly, it relates to a method for producing stable aqueous dispersions of fine spherical particles without the use of emulsifiers. When using polyolefin for applications such as adhesion of paper, textiles, wood boards, metals, etc., and painting, using an organic solvent solution of polyolefin poses problems in the working environment and flammability. started to be used. Originally, polyolefins are non-polar and have no affinity for water, so in order to make polyolefins into aqueous dispersions, a method is generally adopted in which polyolefins are modified to give polarity and an emulsifier is used.
However, in coatings formed from such aqueous dispersions of polyolefins, emulsifiers often remain, which adversely affects the physical properties of the coating. However, it is generally difficult to obtain stable dispersions without the use of emulsifiers. On the other hand, Special Publication No. 45-29909 or Special Publication No. 46-426
No. 20 proposes a method of producing an aqueous dispersion without using an emulsifier by adding an organic solvent solution of a modified polyolefin to water.

However, the modified polyolefins used in these methods are limited to those having a relatively small molecular weight and a relatively high acid value. Therefore, it is not possible to obtain an aqueous dispersion of a polyolefin with a high molecular weight, or the modified polyolefin to be dispersed dissolves in water due to its high acid value, and in either case, these aqueous dispersions do not yield sufficient amounts of water. The drawback was that a high performance coating could not be obtained. The present inventors dissolved a polyolefin composition consisting of a polyolefin and a modified polyolefin in a water-immiscible organic solvent, and then added and mixed it into a basic aqueous solution. The inventors have now discovered that a stable aqueous dispersion can be obtained without the use of a liquid dispersion, and that a film with excellent performance can also be obtained from this aqueous dispersion, and have thus arrived at the present invention.

That is, the present invention comprises 50 to 99 parts by weight of a polyolefin and 1 to 50 parts by weight of a carboxyl group-containing polyolefin having an intrinsic viscosity [η] of 0.05 to 0.5 and an acid value of 30 to 150. is 1
A water-immiscible organic solvent solution of the polyolefin composition of No. 60 to 60 is poured into water containing a basic compound and maintained at a temperature of 140° C. or higher to be dispersed, and the organic solvent is removed. A method for producing an aqueous dispersion of a polyolefin composition, characterized by:

The polyolefin composition used in the method of the present invention comprises a polyolefin and an intrinsic viscosity [η] of 0.05 to 0.
．． 5 and an acid value of 30 to 150.

Here, the polyolefin used in the polyolefin composition is a homopolymer of 1-olefinically unsaturated hydrocarbons such as ethylene, propylene, 1-butene, 4-methyl-1-benzene, or a 1-olefinically unsaturated hydrocarbon thereof. It is a copolymer of hydrocarbons and other olefins.

More specifically, for example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-benzene, ethylene-propylene copolymer, ethylene-1-
Butene copolymer, ethylene-butadiene copolymer, ethylene-propylene-butadiene copolymer, ethylene-propylene-dicyclopentadiene copolymer, ethylene-
Propylene-ethylidene norbornene copolymer, propylene-1-butene copolymer, propylene-butadiene copolymer, ethylene monovinyl acetate copolymer or its saponified product, ethylene-acrylic ester copolymer, propylene-acrylic ester Examples include copolymers. The method of the present invention is generally applied to low to high molecular weight polyolefins with an intrinsic viscosity [η] in the range of 0.1 to 10. In order to obtain this, it is particularly preferable to use a polyolefin in which [η] is in the range of 0.5 to 5. The carboxyl group-containing polyolefin used in the polyolefin composition has an intrinsic viscosity [η] of 0.05 to 0.5 and an acid value in the range of 30 to 150.

More specifically, an olefin polymer containing a carboxyl group and/or an acid anhydride group obtained by modifying the polyolefin by graft copolymerization with an unsaturated carboxylic acid or its anhydride, Carboxyl group-containing polyolefins modified by oxidation with a containing gas, or carboxyl group- and/or acid anhydride-containing polyolefins produced by direct copolymerization of unsaturated carboxylic acids or their anhydrides. Combination can be mentioned. Among these, it is preferable to use a carboxyl group-containing polyolefin modified by graft copolymerization. Unsaturated carboxylic acids or their anhydrides used for modification include acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, 5-norbornene-23-dicarboxylic acid, maleic anhydride, citraconic anhydride. , itaconic anhydride, 5-norbornene 2,3 dicarboxylic acid anhydride, and the like. In order to obtain a stable aqueous dispersion finely divided by the method of the present invention, the carboxyl group-containing polyolefin must have an intrinsic viscosity [η] of 0.05 to 0.5 and an acid value of 30. Furthermore, it is necessary that the intrinsic viscosity [η] be in the range of 0.06 to 0.45 and the acid value be in the range of 35 to 130.
It is preferable that it is in the range of . Here, the acid value is sample 1
It is the η number of potassium hydroxide required for neutralization per 7.
Even if a carboxyl group-containing polyolefin with an acid value lower than 30 or a carboxyl group-containing polyolefin with a high [η] is used, a stable aqueous dispersion cannot be obtained. The polyolefin composition used in the method of the present invention is a composition comprising 50 to 99 parts by weight of the above polyolefin and 1 to 50 parts by weight of the above carboxyl group-containing polyolefin, and has an overall acid value of 1 to 60. A finely divided, stable aqueous dispersion cannot be obtained from a composition whose composition ratio is outside the above range. Furthermore, if the acid value of the composition is less than 1, a stable aqueous dispersion cannot be obtained;
If the size is larger, only the carboxyl group-containing polyolefin in the composition will dissolve in water, making it impossible to obtain an aqueous dispersion. Among the above polyolefin compositions, the method of the present invention can be applied to a composition comprising 70 to 95 parts by weight of polyolefin and 5 to 30 parts by weight of the above carboxyl group-containing polyolefin and having an overall acid value of 2 to 30. preferable. This polyolefin composition is used in the form of a solution dissolved in a water-immiscible organic solvent.

Here, the water-immiscible organic solvent is a solvent that dissolves the polyolefin composition, is not compatible with water, and easily causes phase separation. More specifically, for example, benzene, toluene, xylene, ethylbenzene, cumene,
Aromatic hydrocarbons such as cymene, diisopropylbenzene, trimethylbenzene, and tetralin, aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, octane, kerosene, and light oil, or a mixed solvent of two or more of these are used. The amount of these solvents to be used in the polyolefin composition is not particularly limited as long as the polyolefin composition is completely dissolved, but it is usually in the range of 5 to 20 times the weight ratio. In order to dissolve the polyolefin composition in these solvents, the solvent is usually heated to a temperature of 140 to 300°C. The aqueous dispersion of polyolefin of the present invention can be obtained by pouring a solution of the polyolefin composition prepared by the above method into hot water containing a basic compound.

The basic compounds used here include inorganic basic compounds such as alkali metal compounds, alkaline earth metal compounds, and ammonia, as well as compounds that exhibit basicity in water, such as organic basic compounds. More specifically, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal oxides such as lithium oxide, sodium oxide, and potassium oxide; lithium methoxide, sodium methoxide, Alkali metal alkoxides such as sodium ethoxide, sodium isopropoxide, potassium butoxide; sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium formate, sodium acetate, potassium acetate,
Weak acid salts of alkali metals such as sodium propionate;
Alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide; alkaline earth metal oxides such as calcium oxide, magnesium oxide, strontium oxide, barium oxide; calcium carbonate, magnesium carbonate Weak acid salts of alkaline earth metals such as , calcium bicarbonate, magnesium bicarbonate; ammonia, hydroxylamine, hydrazine; methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, cyclohexylamine, etc. Examples include amines. The amount of these basic compounds used is usually 0.2 chemical equivalent or more, preferably 0.3 to 1.0 chemical equivalent, relative to the carboxyl group in the polyolefin composition. The amount of water used for dispersing the polyolefin composition is not particularly limited, but it is usually 100 parts by weight or more, preferably 150 to 300 parts by weight, based on 100 parts by weight of the polyolefin composition. of basic compounds are dissolved. The aqueous dispersion of the polyolefin composition of the present invention is produced by pouring the solution of the polyolefin composition prepared by the above method into a heated aqueous solution containing a basic compound to disperse it, and removing the organic solvent. be done.

The temperature of the water containing basic compounds must be kept at 140°C or higher, especially between 150 and 250°C.
It is preferable that the temperature is maintained within the range of ℃. At such temperatures, polyolefin compositions typically have a melt viscosity of 105
cps or less. In the method of the present invention, the operation of dispersing a solution of a polyolefin composition in a high-temperature aqueous solution containing a basic compound is carried out in a pressure-resistant container equipped with a powerful stirring device, such as a colloid mill or a homomixer.
In the dispersion mixing system, after the polyolefin composition and the basic compound-containing high temperature aqueous solution are brought into contact, usually 5 to 3
A stable aqueous dispersion can be obtained by continuing stirring for 0 minutes and simultaneously distilling off the organic solvent, or by continuing stirring and then distilling off the organic solvent. The carboxyl group-containing polyolefin in the aqueous dispersion obtained by the method of the present invention is neutralized into a salt when it is dispersed in an aqueous solution containing a basic compound.

In addition, since the temperature of the aqueous solution is higher than the melting point or softening point of the polyolefin composition, the polyolefin composition becomes spheroidal in water, and is further divided into smaller spherical bodies by applying a large shearing force by stirring. A stable aqueous dispersion is obtained. The average particle size of the particles in the aqueous dispersion of the polyolefin composition obtained by the method of the present invention is 3 μ or less, usually 2 μ or less, and this aqueous dispersion is stable even at high concentrations. It has the characteristic that phase separation does not occur even after long-term storage over several months. The aqueous dispersion of the polyolefin composition obtained by the method of the present invention can be used for applications such as painting and adhesion of paper, textiles, wood boards, metals, etc.

In this case, the above-mentioned aqueous dispersion can be used alone, but pigments, plasticizers, thickeners, fillers, etc. can also be mixed therein as required. Next, the method of the present invention will be specifically explained using examples. Reference example 1 (Preparation of carboxyl group-containing polyethylene) [η] is 0
．． 12. 100y of polyethylene wax with a density of 0.977/ml was dissolved in 1000ml of chlorobenzene at 120°C, and dicumyl peroxide was added to it under a nitrogen atmosphere.
．． 8f of heated melt with acrylic acid 257
They were added dropwise at the same time, and the reaction was continued for an additional 2 hours.

After the reaction was completed, the system was cooled and 500 ml of acetone was added to precipitate carboxyl group-containing polyethylene. After filtering, the cake was washed three times with 500 ml of acetone and dried. The obtained carboxyl group-containing polyethylene had an acid value of 1001 [η] of 0.18 and a melting point of 124°C. Reference Example 2 (Preparation of carboxyl group-containing modified polypropylene) [η
] is 0.08, density is 0.917/M. 1000 y of propylene polymer was heated and melted at 170°C under a nitrogen atmosphere, and 10 y of ditertiary butyl peroxide was added to this with stirring.
ml and 100 t of maleic anhydride heated and melted were added dropwise over 2 hours, and the mixture was reacted at 170° C. for 1 hour.

After the reaction was completed, volatile components such as unreacted maleic anhydride and peroxide decomposition products were removed by keeping the mixture under a vacuum of 5 mmHg for 1 hour while stirring at the same temperature. The acid value of the carboxyl group-containing polypropylene product is 60, [η
] was 0.12, and the melting point was 152°C. Reference Example 3 (Preparation of carboxyl group-containing modified polypropylene) In Reference Example 2, [η] was 0.
10. The same procedure as in Reference Example 2 was carried out except that polyethylene having a density of 0.957/TrLl was used and 80y of maleic anhydride was used.

The acid value of the obtained carboxyl group-containing polyethylene was 45.
Jη] was 0.12, and the melting point was 120°C. Reference example
4 (Preparation of carboxyl group-containing polyethylene) In Reference Example 2, instead of polypropylene, [η] was 0.10,
Modification was carried out in the same manner as in Reference Example 2, except that polyethylene with a density of 0.95 y/ml and 357 maleic anhydride were used.

The acid value of the obtained carboxyl group-containing polyethylene was 20.
, [η] was 0.11, and the melting point was 120°C. Reference Example 5 (Preparation of carboxyl group-containing polyethylene) In Reference Example 1, polyethylene wax 1007 with [η] 0.08 and density 0.977/ml was used, digyl peroxide 1.47 was used, and acrylic acid The procedure was the same as in Reference Example 1 except that 437 was used.

The acid value of the obtained carboxyl group-containing polyethylene was 16.
5, [η] 0.15, melting point 124°C. Example
1 [η] is 0.8, density 0.965y/ml, melting point 130
Acrylic acid graft modified polyethylene wax synthesized in Reference Example 1 ([η] 0.1
8, acid value 100, melting point 124°C) 407, the overall acid value of the composition was 20.

This composition and benzene 20007 were charged into an autoclave and stirred while heating to 180°C to form a uniform solution. 1500 ml of water and 1,57 ml of sodium hydroxide (0.52 equivalent to the carboxyl group in the composition) were placed in a pressure-resistant homomixer with an internal volume 41 connected to the top of the flash distillation column, and heated to 180°C. While stirring at 5000 rpm, a solution of the above-mentioned acrylic acid grafted polyethylene wax and polyethylene composition is supplied by a plunger pump for 4 hours, and at the same time, a mixture of benzene and water is azeotropically removed from the flash distillation column at the top. At the same time, the amount of water distilled off by distillation was added. After further stirring for 30 minutes, the particles in the aqueous dispersion obtained by cooling to room temperature were spherical, the number average particle size was 1μ or less, and the type B viscosity of the dispersion was 7 cps (25°C). Almost no phase separation was observed even after the sample was left for 7 days. Comparative Example 1 The same procedure as in Example 1 was conducted except that sodium hydroxide was not used.

As a result, the composition of polyethylene and acrylic acid graft-modified polyethylene wax was hardly dispersed and was only scattered in the water in the form of lumps with a particle size of 5 to 1 TLTIL. Comparative Example 2 The same procedure as in Example 1 was carried out except that the temperature of the aqueous sodium hydroxide solution used to prepare the aqueous dispersion was changed to 100°C.

The number average particle size of the particles of the composition of polyethylene and acrylic acid graft-modified polyethylene wax in the resulting aqueous dispersion was 50 μm. This aqueous dispersion underwent almost complete phase separation after one day. Example 2 [η] is 1.0, density 0.9407/ml, melting point 123
Ethylene-1-butene copolymer (1-butene content 4
mol%) 28.5k9 [η] is 0.13, acid value 75, melting point 100°C ethylene-acrylic acid copolymer 1.5k9
(Total acid value: 3.75) and 200 kg of hexane were placed in a pressure container and stirred while heating to 210°C to form a homogeneous solution.

Water 601 and potassium hydroxide 1007 (0.89 equivalent to the carboxyl group in the composition) were placed in a pressure vessel with an internal volume of 1001 and equipped with a turbine stirrer and a flash distillation column at the top, and heated to 200°C. ,500rp
A hexane solution of the above-mentioned polyethylene composition was charged into the reactor using a plunger pump over a period of 8 hours while stirring at m, and a mixture of hexane and water was distilled off from the flash distillation column at the top.

Further, while stirring was continued for 1 hour, the amount of water removed by distillation was added, and the particles in the aqueous dispersion obtained by cooling to room temperature were spherical and had a number average particle size of 2μ. The B-type viscosity of the liquid was 8 cps (25°C), and even when the dispersion was left for 7 days, almost no phase separation was observed. Example 3 Polypropylene 1607 with [η] of 0.3, density of 0.917/ml, and melting point of 165°C and maleic anhydride graft-modified polypropylene synthesized in Reference Example 2 ([η] of 0.12, acid value 60, melting point 152°C) 407 (total acid value 12) was mixed with benzene 1
Using a solution dissolved in 5007 under stirring at 200°C,
Dispersion was carried out in the same manner as in Example 1 in a 200° C. aqueous solution containing 1.77 sodium hydroxide (1.0 equivalent to the carboxyl group in the composition).

The particles in the obtained aqueous dispersion were spherical, the number average particle size was 1 μm or less, and the type B viscosity of the aqueous dispersion was 8 cps (25°C
), and even when the aqueous dispersion was allowed to stand for 7 days, almost no phase separation was observed. Example 4 In Example 3, the amount of sodium hydroxide in the aqueous solution was reduced to 0.
．． 57 (The carboxyl acid anhydride group in the composition is 2
The aqueous dispersion obtained was stable, with no phase separation even after standing for 7 days, and the particles in the aqueous dispersion were stable. The number average particle size of the dispersion was 2 μ, which was a little large, but it was spherical and uniform, and the aqueous dispersion was sufficiently usable for practical use.

Example 5 Using the same method as in Example 1, [η] was 1.5 and the density was 0.9.
1607, a 90% saponified product of ethylene monovinyl acetate copolymer (content of vinyl acetate units: 28 wt%) with a melting point of 93°C and the acrylic acid graft-modified polyethylene wax synthesized in Reference Example 1 ([η] is 0). Same as Example 1 except that a composition consisting of .8, acid value 100, melting point 12'C)40f7 (total acid value 20) was used, and the temperature of the sodium hydroxide-containing aqueous solution used for dispersion was 220 ° C. It was operated in the same way.

The particles in the obtained aqueous dispersion were spherical, the number average particle size was 1 μ, and the B type viscosity of the aqueous dispersion was 70.8 (25°C). Even if the aqueous dispersion was left for 7 days, Almost no phase separation was observed. Example 6 In Example 2, [
η] is 0.70, density 0.9207/ml and melting point 1
Ethylene propylene copolymer (propylene content 5 mol%) at 20°C 27k9 and [η] 0.5, melting point 87
℃, density 0.94 t/ml and acid value 62 ethylene-
A composition consisting of 3 kg of methacrylic acid copolymer (total acid value 62) was used, and the basic compound-containing aqueous solution contained 132 t of sodium hydroxide (1.0 equivalent to the carboxyl group in the composition). The same procedure as in Example 2 was carried out except that 170° C. sodium hydroxide aqueous solution 601 was used.

The particles in the resulting aqueous dispersion were spherical and had a number average particle size of 2.
μ, the B-type viscosity of the aqueous dispersion was Cps (25° C.), and almost no phase separation was observed even after standing for 7 days. Example 7 Synthesized using 27.0 kg of ethylene-1-butene copolymer (1-butene content: 4 mol %) with [η] of 2.0 and density of 0.9457/ml in Example 2 and Reference Example 3. A composition (total acid value 45) consisting of 3.0 kg of maleic anhydride graft modified polyethylene with an acid value of 45 and [η] of 0.12 was used, hexane 200k9 was used as a solvent, and a basic compound-containing composition was used. An aqueous solution 601 of potassium hydroxide 165V (1.0 equivalent to the carboxyl group in the above composition) was used as the aqueous solution, and the temperature of the aqueous solution during dispersion was 180°C, and the stirring speed was 350r.
The same procedure as in Example 2 was performed except that pm was used.

The particles in the aqueous dispersion obtained by cooling the temperature to room temperature are spherical and have a number average particle size of 1μ or less, and the B type viscosity of the aqueous dispersion is 1.
3 cps (25° C.), and the aqueous dispersion showed almost no phase separation even after being left for 7 days. Comparative example 3 [η] is 0.8, density 0.9657/ml, melting point 130
℃ polyethylene 120y, [η] 0.11, acid value 20
, a composition consisting of graft-modified polyethylene 807 prepared in Reference Example 4 (total acid value 8) having a density of 0.957/ml and a melting point of 120°C was used, and benzene 200 was used as a solvent.
07, an aqueous solution 15007 of potassium hydroxide 0.87 (1.0 equivalent to the carboxyl group in the above composition) was used as the basic compound-containing aqueous solution, and the temperature of the aqueous solution during dispersion was set to 180°C. , stirring speed 5000 rpm
The operation was carried out in the same manner as in Example 1, with each charging time being 4 hours.

The number average particle size of the particles in the obtained aqueous dispersion was 50μ,
After the dispersion was allowed to stand for 1 hour, phase separation occurred almost completely. Example 8 [η] 6,0, density 0.9807/ml, melting point 136°C
polyethylene 1607 and [η] 0.12, acid value 45,
A composition consisting of graft modified polyethylene 407 prepared in Reference Example 3 having a melting point of 120'C (overall acid value 9.0)
Hexane 20007 was used as the solvent, potassium hydroxide 0.9y (
An aqueous solution 15007 (1.0 equivalent to the carboxyl group in the above composition) was used, and the temperature of the aqueous solution during dispersion was 250°C, and the stirring speed was 5000 r.p.m. p. m. The same procedure as in Example 1 was carried out except that the charging time was changed to 4 hours.

The number average particle diameter of the particles in the obtained aqueous dispersion was 3 μm, and almost no phase separation was observed even when the dispersion was allowed to stand at room temperature for 3 days. Comparative example 4 [η] 0.8, density 0.9657/Me, melting point 130°C
polyethylene 1207 and [η] 0.15, acid value 1
65, a composition consisting of 80y of acrylic acid-grafted modified polyethylene wax synthesized in Reference Example 5 with a melting point of 124°C (total acid value 66), and 9.4y of sodium hydroxide (the above composition) was used as a basic compound-containing aqueous solution. The same procedure as in Example 1 was carried out using 1,500 ml of an aqueous solution of 1 equivalent to the carboxyl group in the product.

Claims (1)

[Claims] 1. 50 to 99 parts by weight of polyolefin, an intrinsic viscosity [η] of 0.05 to 0.5, and an acid value of 30
A water-immiscible organic solvent solution of a polyolefin composition comprising 1 to 50 parts by weight of a polyolefin containing 1 to 150 carboxyl groups and having an overall acid value of 1 to 60,
A method for producing an aqueous dispersion of a polyolefin composition, which comprises dispersing it in water containing a basic compound and maintained at a temperature of 140°C or higher, and removing the organic solvent. 2. The method according to claim 1, wherein at least one solvent selected from the group consisting of aromatic hydrocarbons and aliphatic hydrocarbons is used as the water-immiscible organic solvent. 3. As a polyolefin composition, 70 to 95 parts by weight of a polyolefin having [η] of 0.5 to 5 and a carboxyl group-containing polyolefin having an intrinsic viscosity [η] of 0.06 to 0.45 and an acid value of 35 to 130. 5 to 30 parts by weight, and the total acid value is 2 to 30.
3. The method according to claim 1 or 2, wherein the polyolefin composition is used. 4. The method according to any one of claims 1 to 3, wherein the carboxyl group-containing polyolefin is a carboxyl group-containing polyolefin modified by graft copolymerization of an unsaturated carboxylic acid or its anhydride. 5. The method according to any one of claims 1 to 4, wherein the basic compound-containing aqueous solution is an aqueous solution containing 0.3 to 1.0 equivalents of the basic compound relative to the carboxyl group in the polyolefin composition. . 6 The temperature of the basic compound-containing aqueous solution is 150 to 25
Claims 1 to 5 characterized in that the temperature is 0°C.
Any of the methods listed.