JPH03122125A - Production of aqueous dispersion of polyolefin composition - Google Patents

Abstract

PURPOSE:To obtain aqueous dispersion of ultrafine spherical particles not causing phase separation without using a surfactant in producing an aqueous dispersion of polyolefin by blending a polyolefin composition in a molten state with a basic substance and water by adding an ester. CONSTITUTION:50-99 pts. wt. polyolefin (preferably one having <=5 dl/g intrinsic viscosity) and 1-50 pts. wt. carboxyl group- or acid anhydride group-containing polyolefin (preferably one having 0.04-1 dl/g intrinsic viscosity and 20-150 acid value) are heated and melted to give a polyolefin composition in a molten state, which is added and blended with a water dispersion medium comprising >=0.2 chemical equivalent based on carboxyl group or acid anhydride group in the composition of a basic substance (e.g. sodium) and water heated to 120-300 deg.C, cooled to room temperature and mixed with an ester (preferably ester of 1-4C aliphatic monocarboxylic acid and 1-4C alcohol) to give an aqueous dispersion of polyolefin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention provides a method for producing an aqueous dispersion of a polyolefin composition, which is resistant to phase separation and has fine spherical particles, even without the use of a surfactant. The present invention relates to a method for producing an aqueous dispersion of a polyolefin composition such that an aqueous dispersion of a polyolefin composition can be obtained.

Technical Background of the Invention When using polyolefins for adhesion, lamination, painting, or coating of paper, metal, etc., rather than dissolving the polyolefin in an organic solvent and using it as a polyolefin solution, it is used as an aqueous dispersion of polyolefin. It is more advantageous to use it because it does not worsen the working environment and there is no risk of fire or ignition. For this reason, a method for obtaining an aqueous dispersion of polyolefin using a surfactant has been developed. However, in this method, the surfactant remains in the resulting coating film, which may adversely affect the physical properties of the resulting coating film.

In order to solve these problems, the present applicants filed the Japanese Patent Publication No. 58-4220? In this issue, without using surfactants,
A method of emulsifying a polyolefin composition is presented. According to this method, it is stated that it is necessary to add a basic substance to the aqueous dispersion of the polyolefin composition.

In such an aqueous dispersion of a polyolefin composition, it is preferable that the particle size of the polyolefin particles in the aqueous dispersion is small in terms of the uniformity and density of the resulting film, the stability of the emulsion, and the like. The particle size of the polyolefin particles in the aqueous dispersion is related to the amount of a basic substance such as potassium hydroxide added during emulsification, and generally becomes smaller as the amount of the basic substance increases. However, if a large amount of basic substance is used to increase the pH of the aqueous dispersion, safety during operation or miscibility with other additive chemicals will decrease.

For this reason, a method is generally used in which an acid is added to an aqueous dispersion of a polyolefin composition having a high pH to neutralize the dispersion. However, according to research conducted by the present inventors, it has been found that when an acid is added to an aqueous dispersion of a polyolefin composition, a phenomenon occurs in which the added acid creates a locally acidic atmosphere, making it easier for polyolefin particles to aggregate. It was done.

Purpose of the Invention The present invention provides an aqueous dispersion of a polyolefin composition that is stable and nearly neutral without agglomeration of polyolefin particles and can be efficiently produced at a high concentration. The purpose is to provide a manufacturing method for.

Summary of the Invention The object of the present invention is to obtain 50 to 99 parts by weight of a polyolefin and 1 part of a polyolefin containing a carboxyl group or an acid anhydride group.
A polyolefin composition in a molten state consisting of ~50 parts by weight, a basic substance and water in an amount of 0.2 chemical equivalents or more relative to the carboxyl group or acid anhydride group in the composition, and at a temperature of 120 to 300 ° C. When producing a polyolefin aqueous dispersion by mixing with an aqueous dispersion medium heated to
This is achieved by adding an ester to the aqueous dispersion to produce an aqueous dispersion of the polyolefin composition.

According to the present invention, polyolefin particles do not aggregate, and a stable and nearly neutral aqueous dispersion of a polyolefin composition can be efficiently produced at a high concentration.

DETAILED DESCRIPTION OF THE INVENTION A method for producing an aqueous dispersion of a polyolefin composition according to the present invention will be specifically described below.

In the present invention, as the polyolefin, (i) ethylene,
Waxes, resins, rubber-like materials, etc. made of single or copolymers of α-olefinic unsaturated hydrocarbons such as propylene, 1-butene, and 4-methyl-1-pentene are used, and specifically, polyethylene, polypropylene, poly-
1-butene, poly-4methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-α-butene copolymer, etc. are used.

Further, in the present invention, as the polyolefin, (i) a rubbery copolymer of two or more of the above α-olefins and a conjugated or non-conjugated diene, such as an ethylene-propylene-butadiene copolymer, an ethylene-propylene-dicyclopentadiene copolymer; polymer, ethylene propylene-ethylidenenorbornene copolymer, ethylene-propylene-1□5-hexadiene copolymer, isobutyne-isoprene copolymer,
(iii) Copolymers of α-olefins and conjugated or non-conjugated dienes, such as ethylene-butadiene copolymers, ethylene-ethylidene norbornene copolymers, (1v
) α-olefins, especially copolymers of ethylene and vinyl acetate, and completely or partially saponified products thereof; (V) Grafts obtained by grafting the above-mentioned conjugated or non-conjugated dienes or vinyl acetate onto α-olefins alone or copolymers. Copolymers and completely or partially saponified products thereof, or (vl) compositions consisting of two or more of the above polymers or copolymers are used.

In the present invention, in order to obtain sufficiently fine particles, it is preferable that [η] of the polyolefin is 5 dI/g or less.

Further, the carboxyl group- or acid anhydride group-containing polyolefin used in the present invention is an olefin polymer containing a carboxyl group and/or an acid anhydride group, and specifically, the above α-olefin and the α-, β- Copolymers with unsaturated carboxylic acids and modified polyolefins obtained by grafting α,β-unsaturated carboxylic acids or their anhydrides onto polyolefins are commonly used.

Polyolefins containing carboxyl groups or acid anhydride groups are
The [η] is usually 0.04 to 1 dl/g, preferably 0.
06~0.8dA! /g, and its acid value is 20-15
0, preferably 25 to 130.

Here, the intrinsic viscosity [η] is the viscosity determined from the measured value of reduced viscosity in a decalin solution at 135°C.

Moreover, the acid value is the number of potassium hydroxides required for neutralization per gram of sample polyolefin.

Examples of the α,β-unsaturated carboxylic acid used in deriving a polyolefin containing a carboxyl group or an acid anhydride group include monocarboxylic acids and dicarboxylic acids.

As monocarboxylic acids, specifically, aliphatic carboxylic acids containing 6 or less carbon atoms, preferably 4 or less carbon atoms, such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid, are used, and as dicarboxylic acids, Specifically, aliphatic carboxylic acids such as maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, 5-
Norbornene-2,3-dicarboxylic acid, its nuclear methyl substituted product, its endomethylene group halogen substituted product, etc. are used. Such acids may be anhydrous.

In the polyolefin composition used in the present invention, the polyolefin is used in an amount of 50 to 99 parts by weight, and the carboxyl group-containing polyolefin is used in an amount of 1 to 50 parts by weight.

In addition, basic substances include alkali metals, alkaline earth metals, substances that act as bases in water such as ammonia and amines, alkali metal oxides, hydroxides, weak acid salts, hydrides, and alkaline earth metals. Substances that act as bases in water, such as oxides, hydroxides, weak acid salts, and hydrides, and alkoxides of these metals are used. Specifically, the following compounds are used as such basic substances.

Examples of alkali metals include sodium and potassium; examples of alkaline earth metals include calcium, strontium, and barium; specific examples of amines include inorganic amines such as hydroxylamine and hydrazine. Organic amines such as , methylamine, ethylamine, ethanolamine, and cyclohexylamine are used, and oxides, hydroxides, and hydrides of alkali metals and alkaline earth metals include sodium oxide, peroxide, etc. Sodium, potassium oxide, potassium peroxide, calcium oxide, strontium oxide, barium oxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, sodium hydride, potassium hydride, calcium hydride, etc. Examples of weak acid salts of alkali metals and alkaline earth metals include sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, sodium acetate, potassium acetate, and calcium acetate. Specific examples of ammonia and amine compounds include ammonium hydroxide, quaternary ammonium compounds such as tetramethylammonium hydroxide, and hydrazine hydrate.

The ester may be one that can be hydrolyzed by excess basic substance and neutralize the basic substance.Specifically, methyl formate, ethyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate are used. , octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, ethyl caproate, ethyl chloroacetate, ethyl dichloroacetate, ethyl hydroxyacetate, ethyl acrylate, methyl methacrylate, ethyl crotonate, etc. Carboxylic acid esters, aliphatic polycarboxylic acid polyesters such as diethyl oxalate, dibutyl malonate, dimethyl succinate, diethyl glutarate, diethyl malate, triethyl citrate, diethyl chlorosuccinate, diethyl maleate, dimethyl fumarate, cyclohexane carboxylate Alicyclic carboxylic acid esters such as ethyl benzoate, aromatic carboxylic acid esters such as ethyl benzoate, benzyl benzoate, methyl toluate, methyl anisate, dimethyl phthalate, γ-butyrolactone, δ-valerolactone, coumarin, phthalide Lactones such as methyl benzenesulfonate, sulfonic acid esters such as methyl benzenesulfonate, and inorganic acid esters such as dimethyl sulfate, ethyl nitrate, triethyl phosphate, and diethyl carbonate are used.

Among these, esters of aliphatic monocarboxylic acids having 1 to 4 carbon atoms and alcohols having 1 to 4 carbon atoms, and/or esters of aliphatic polycarboxylic acids having 2 to 8 carbon atoms and alcohols having 1 to 4 carbon atoms. Polyester is preferred.

In the present invention, when producing an aqueous dispersion of a polyolefin composition, a pressure-resistant container equipped with a strong stirring blade, preferably a high-performance dispersion means that generates a large shear force, such as a colloid mill, a ball mill, a roll mill, a homogeneous A mixer or the like is used.

Next, a specific example of a method for producing an aqueous dispersion of a polyolefin composition according to the present invention will be described.

Usually 0.2 chemical equivalent or more, preferably 0.3 to 1.0 chemical equivalent to the carboxyl group or acid anhydride group in the polyolefin composition charged into the pressure container (the acid anhydride group has two carboxyl groups) ) and water, and the system is heated to a melting point higher than the melting point of the polyolefin and the carboxyl group- or acid anhydride group-containing polyolefin constituting the polyolefin composition, preferably the polyolefin composition. Heat to a temperature at which the melt viscosity of the substance becomes 105 cps or less. This temperature varies greatly depending on the type of polyolefin or carboxyl group- or acid anhydride group-containing polyolefin, but is usually 120~
300°C, more preferably 30°C or more higher than the melting point of the high melting point component in the polyolefin composition, and 300°C or more
Preferably, the temperature is up to 00°C.

The polyolefin composition is heated and melted in a separate container equipped with a mixing means, and after thorough mixing, it is gradually charged into the water using a pump or the like, or the polyolefin composition is simultaneously melted and mixed using an extruder, etc. in a pressure container. Gradually charge into water. The charging rate is preferably between 1 and 100 g per 1000 ml of water in 10 minutes. The amount of water used in the polyolefin composition to be dispersed may be equal to or more than the same amount by weight, but from a practical point of view it should be 20 to 100% by weight.
It is enough to choose.

After charging a predetermined amount of the polyolefin composition into the dispersion system, it is usually post-stirred for 30 minutes or more, and then cooled to room temperature to form a spherical shape with a number average particle size of 3 μm or less per 100 particles, usually 2 μm or less. An aqueous dispersion of a polyolefin composition in which phase separation hardly occurs is obtained. After the aqueous dispersion of the polyolefin composition is prepared in this manner, an ester is added to the aqueous dispersion for neutralization.

In the present invention, an ester is added instead of an acid in order to neutralize the excess basic substance and bring the pH close to neutral. At this time, the ester is first hydrolyzed in a basic atmosphere,
Neutralization is performed by the generated acid. The amount of ester added can be arbitrarily determined depending on the pH of the target aqueous dispersion.

The ester may be added at any time, but it is preferably when the temperature of the aqueous dispersion has cooled to below the melting point of the polyolefin composition used.

Effects of the Invention According to the present invention, it is possible to efficiently produce a highly concentrated aqueous dispersion of a polyolefin composition that is stable and nearly neutral without agglomeration of polyolefin particles.

Examples Examples of the present invention will be described below. In addition, the measurement of physical property values in Examples was performed by the following method.

[η]; Determined from the measured value of reduced viscosity in a decalin solution at 135°C.

Density: Determined by density gradient method.

Melting point: Determined by differential thermal analysis.

Particle size: Measured using a Coulter counter.

Example 1 [η is 0.22 dl/g, density is 0.98 g/g]
Polyethylene 180 with a melting point of 3 and a melting point of 126°C
0g, [η] is 0.16, density is 0.93, melting point is 107°C, and acid value is 30 KOH/g.
200 g of carboxyl group-containing polyethylene was added and mixed and melted at 140° C. to prepare a molten polyolefin compound. - Potassium hydroxide aqueous solution was prepared by dissolving 22.4 g of potassium hydroxide in 8000 g of water.

Next, the above polyolefin composition was put into a pressure-resistant homomixer having an internal capacity of 0.51 at a flow rate of 1280 g/waiting time and the above potassium hydroxide aqueous solution was put at a flow rate of 1500 g/waiting time,
While heating to 140° C. and stirring at 11,000 rpm, continuous emulsification was carried out using a homomixer for a retention time of 10 minutes. After completion, the particles in the aqueous dispersion obtained by cooling to room temperature were spherical and had an average particle size of 3.1 μm. Also, type B viscosity is 82
0 (23°C) and the pH was 9.5.

Next, 200 g of the obtained aqueous dispersion was heated to 60°C,
After adding 6.8 g of ethyl acetate and continuing stirring for 2 hours,
I took out the contents. 1 on the way, 0.5 hours later and 1 hour later
The above measurements were performed by sampling 0 ml each.

The results are shown in Table 1.

Table 1 Physical properties of aqueous dispersion before and after addition of ethyl acetate 2 Before addition 9.5 3
．． 10.5 hours later 8.9 3.2〃8.
8 3.3 2 ” 8.6
The quality of the aqueous dispersion obtained after 3.32 hours was unchanged from that before addition, except for the pH of the system.

Example 2 In Example 1, ethyl formate 5 was used instead of ethyl acetate.
．． After adding 9 g and continuing stirring for 0.5 hour, the contents were taken out and the following measurements were performed in the same manner as in Example 1.

The results are shown in Table 2.

Before addition 9.5 3.
After adding 1 8.6
3.2 Comparative Example 1 When 11.1 g of acetic acid diluted to 10% by weight was added to 200 g of the same emulsion as in Example 1 while being stirred at 60°C, local aggregation of emulsion particles immediately occurred. was generated, a uniform emulsion could not be obtained, and the liquid portion was not neutralized at the same pH as the original, making it impractical.

Claims (1)

[Scope of Claims] 1. A polyolefin composition in a molten state consisting of 50 to 99 parts by weight of a polyolefin and 1 to 50 parts by weight of a polyolefin containing a carboxyl group or an acid anhydride group, and contains a basic substance and water of 0.2 chemical equivalent or more, and 120 to 3
A method for producing an aqueous dispersion of a polyolefin composition, which comprises adding an ester to the aqueous dispersion when the aqueous dispersion is produced by mixing the aqueous dispersion medium heated to a temperature of 0.000C. 2. The intrinsic viscosity [η] of the polyolefin is 5 dl/g or less, and the intrinsic viscosity [η] of the carboxyl group-containing polyolefin is 5 dl/g or less.
η] is 0.04 to 1 dl/g, the manufacturing method according to claim 1. 3. The acid value of the carboxyl group-containing polyolefin is 20 to 1.
50. The manufacturing method according to claim 1, wherein the manufacturing method is 50.