JP2008056747A - Method for preparing polyolefin resin emulsion and polyolefin resin emulsion obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a polyolefin resin emulsion, whereby the amount of surfactant used can be reduced and physical properties of a coating can be improved, and the polyolefin resin emulsion obtained thereby. <P>SOLUTION: The preparation method used comprises a step of adding a polyolefin resin solution to a surfactant phase containing a surfactant, water and a polyhydric alchol at a weight ratio of surfactant/polyhydric alcohol/water=10/(1-30)/(15-45) to form an O/D gel emulsion whose continuous phase is the surfactant phase and a step of adding water to the gel emulsion so that the continuous phase changes from the surfactant phase to an aqueous phase to yield an O/W emulsion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polyolefin resin emulsion and a polyolefin resin emulsion obtained thereby.

  Polyolefin-based resins such as polypropylene have high chemical stability, are inexpensive, have a good balance of physical properties, and are recyclable, so the amount used is automobile parts, household appliances, household Increasing year by year, mainly for molded products for household goods.

  However, since the polyolefin-based resin does not contain a functional group rich in reactivity on the surface, it has a drawback that it is difficult to be applied and adhesion is difficult.

  For this reason, in the case of coating or adhesion to a polypropylene-based substrate, modified (including chlorinated) polyolefins having relatively good adhesion have been used in the paint, adhesive or ink field.

  However, when using the above-mentioned polyolefin-based resins, aromatic organic solvents such as toluene and xylene are generally used, which is a problem from the viewpoint of health and safety and environmental pollution.

  In recent years, due to consideration for these environmental problems, water-based systems have been actively studied, and attempts to produce aqueous dispersions have been made (for example, Patent Documents 1 to 4).

  However, in the prior art, the addition amount of the surfactant used in the emulsification process is large, and the deterioration of the physical properties of the polymer due to this is regarded as a problem. That is, conventionally, for emulsification of a polyolefin-based resin, a phase inversion emulsification method has been used in which a surfactant is mixed in a polymer solvent solution and then water is gradually added to perform phase change.

  In this method, a large amount of a surfactant is required to emulsify and stabilize the hydrophobic polymer, which causes a decrease in the physical properties of the polymer after the emulsion is used.

On the other hand, a surfactant phase emulsification method (D phase emulsification method) is known as an emulsification method other than the phase inversion emulsification method (Non-patent Document 1). However, this is difficult to mix due to the step of gradually adding the substance to be emulsified to the surfactant phase formed by the surfactant, polyhydric alcohol and water, and emulsification of the polymer solution with high viscosity It was not applied to.
JP-A-5-209006 JP-A-5-287251 JP-A-6-287521 Japanese Patent Laying-Open No. 2005-163030 Literature on D phase emulsification method: Journal of Chemical Society of Japan, 1983, (10), pp. 1399 to 1404, “Preparation of O / W emulsion with fine emulsified droplets by surfactant (D) phase emulsification method”

  The present invention has been made in view of the above, and provides a production method for obtaining a polyolefin resin emulsion in which the amount of surfactant used is reduced and the film properties are improved, and a polyolefin resin emulsion obtained thereby. With the goal.

  In order to solve the above-described problems, the method for producing a polyolefin resin emulsion of the present invention comprises a surfactant, water, and a polyhydric alcohol, wherein the surfactant / polyhydric alcohol / water = 10/1 to 30/15. A polyolefin-based resin solution is added to a surfactant phase contained in a ratio (however, a weight ratio) within a range of ˜45 to form an O / D type gel emulsion in which the continuous phase is a surfactant phase. And a step of adding water to the gel emulsion to change the continuous phase from a surfactant phase to an aqueous phase to form an O / W emulsion.

  In the above, the amount of the surfactant used is preferably 1 to 15% by weight based on the polyolefin resin.

  The polyolefin resin emulsion of the present invention is obtained by the above production method, and the average particle diameter of the emulsified droplets is preferably 0.1 to 5 μm.

  According to the production method of the present invention, it is possible to obtain a polyolefin resin emulsion capable of reducing the amount of the surfactant used conventionally and improving the physical properties of the film.

  The polyolefin resin referred to in the present invention includes polyolefin, chlorinated polyolefin, and modified polyolefin modified with unsaturated carboxylic acid and / or acid anhydride.

  Polyolefin is a homopolymer of ethylene or propylene, or ethylene or propylene and other comonomers such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc. It is a random copolymer or block copolymer with 2-6 α-olefin comonomers. Two or more kinds of these comonomers may be copolymerized.

  The chlorinated polyolefin means one in which a part of hydrogen atoms in the polyolefin is replaced with chlorine.

  Furthermore, the polyolefin modified with an unsaturated carboxylic acid and / or an acid anhydride refers to a polyolefin modified with an α, β-unsaturated carboxylic acid or an acid anhydride thereof.

  Examples of α, β-unsaturated carboxylic acids or acid anhydrides used in the modification reaction include maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, mesaconic acid, itaconic acid, itaconic anhydride, Examples include aconitic acid and anhydrous aconitic acid. These monomers may be used alone, but when two or more of these monomers are used in combination, the physical properties of the coating film are often improved.

  The polyolefin resin produced by a known method can be used, and the production method of the polyolefin resin emulsion of the present invention is not limited at all by the production method and the degree of modification.

  In the present invention, the polyolefin resin emulsion is produced using a so-called surfactant (D) phase emulsification method (hereinafter referred to as D phase emulsification method). The D phase emulsification method is described in “Creation of O / W emulsion having fine emulsified droplets by surfactant (D) phase emulsification method” (Journal of Chemical Society of Japan, 1983, (10), pages 1399 to 1404). The first step of forming an O / D type gel emulsion by adding oil to the surfactant phase (D phase) containing water and polyhydric alcohol, and adding water to this gel emulsion Then, it is an emulsification method comprising a second stage in which the continuous phase is changed from a surfactant to water to obtain an O / W emulsion.

  In order to obtain a polyolefin resin emulsion by the D phase emulsification method in the present invention, as a first step, a small amount of water is added to a surfactant and a dihydric or higher hydroxyl group-containing compound (polyhydric alcohol) solvent, and isotropic. A liquid is prepared, and a polyolefin resin solution (oil phase) is added to this with stirring to form a transparent gel that is soluble in water. This is diluted in water in the second stage, and the continuous phase is surface-active. What is necessary is just to change from an agent phase to an aqueous phase. Here, the polyolefin resin solution is a solution obtained by dissolving a polyolefin resin in an aromatic organic solvent such as toluene or xylene.

  The blending ratio of the surfactant, polyhydric alcohol and water in preparing the isotropic liquid is in parts by weight and is in the range of surfactant / polyhydric alcohol / water = 10/1 to 30/15 to 45. Preferably, the surfactant / polyhydric alcohol / water is within the range of 10/5 to 20/20 to 40.

  When the ratio of the polyhydric alcohol is more than 30 parts, even if the polyolefin resin solution is added, it is separated into two phases and it becomes difficult to form the D phase. On the other hand, if the amount is less than 1 part, the gel viscosity is high and the stirring effect is low, so that a long stirring time is required to obtain an emulsion having a uniform particle size, and the production efficiency is lowered.

  When the proportion of water exceeds 45 parts, even if the polyolefin resin solution is added, it is separated into two phases and it becomes difficult to form the D phase. On the other hand, if it is less than 15 parts, it becomes a high-viscosity gel when a small amount of plasticizer is added, the stirring effect becomes low, a long stirring time is required to make an emulsion with a uniform particle size, and the production efficiency is low. Go down.

  The amount of the surfactant is preferably 1 to 15% (% by weight, the same applies hereinafter) with respect to the polyolefin resin. The amount of the surfactant is preferably smaller from the viewpoint of improving the physical properties of the coating film of the resin emulsion. In this sense, the amount is more preferably 3 to 7%.

  In the present invention, a nonionic surfactant is used as the surfactant. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, Sugar fatty acid esters and the like can be appropriately used alone or as a mixture of two or more. The HLB value is preferably 12 to 20, and outside this range, the compatibility with the polyolefin resin deteriorates and emulsification tends to be difficult.

  The D-phase emulsification method is usually an emulsification method using a nonionic surfactant as described above, but a small amount of an ionic surfactant may be used in combination. Examples of ionic surfactants include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, N-acyl amino acid salts, carboxylates, phosphate esters and other anionic surfactants, alkyl ammonium salts, and the like. Examples include amphoteric surfactants such as cationic surfactants, alkyl (amido) betaines, and alkyldimethylamine oxides.

  The polyhydric alcohol is not particularly limited, and the following divalent, trivalent, tetravalent or higher alcohols can be used.

  Examples of dihydric alcohols include ethylene glycol, polyoxyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,2-, 1,3- and 1,4-butylene glycol, 2-ethylhexanediol, etc. , And these alkylene oxide adducts.

  Examples of the trihydric alcohol include glycerin, trimethylolpropane and the like, and alkylene oxide adducts thereof.

  Examples of the tetrahydric or higher polyhydric alcohol include glucose, sucrose, sorbit, pentaerythritol and the like, and alkylene oxide adducts thereof.

  These may be used as a mixture of two or more. Of these, ethylene glycol and propylene glycol are preferred.

  The emulsion obtained by the production method of the present invention preferably has an average particle size of the emulsion droplets of 0.1 to 5 μm. When the average particle size of the emulsified droplets is less than 0.1 μm, the viscosity of the emulsion becomes high and handling becomes difficult, and when it exceeds 5 μm, the storage stability is deteriorated.

  Examples of the present invention are shown below, but the present invention is not limited to the following examples.

[Example 1]
Add 5 parts of nonionic surfactant Neugen EA-177 (Daiichi Kogyo Seiyaku Co., Ltd.), 1 part of ethylene glycol and 20 parts of water to the emulsifier (TK machine mix manufactured by Tokushu Kika Kogyo Co., Ltd.) It was dissolved uniformly. A solution prepared by dissolving 100 parts of maleic anhydride / acrylic modified polyolefin resin (Nippon Paper Chemical Co., Ltd. aurolene) in 200 parts of toluene under stirring of the anchor (rotation speed: 60 rpm) was gradually added over 1 hour. At the end of the addition, it was blue and had a transparent gel. Stirring was further continued for 30 minutes, and 250 parts of water was added to obtain an emulsified dispersion. Thereafter, toluene was distilled off under reduced pressure to obtain a milky white emulsion having a solid content of 31% and an average particle size (measured with a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation) of 0.5 μm.

[Example 2]
The same operation as in Example 1 was performed except that 3 parts of a nonionic surfactant DKS NL-180 (Daiichi Kogyo Seiyaku Co., Ltd.), 2.5 parts of propylene glycol and 31 parts of water were added to the emulsifier. A milky white emulsion having a solid content of 30% and a particle size of 0.6 μm was obtained.

[Comparative Example 1]
Add 5 parts of Neugen EA-177 (Daiichi Kogyo Seiyaku Co., Ltd.) to a solution of 100 parts of maleic acid / acrylic modified polyolefin resin (Nippon Paper Chemical Co., Ltd. aurolene) in 200 parts of toluene. And completely dissolved. Thereafter, 20 parts of water was added all at once under stirring of the anchor (rotation speed: 60 rpm). However, the oil layer separated and could not be emulsified.

[Comparative Example 2]
Add 20 parts Neugen EA-177 (Daiichi Kogyo Seiyaku) to a solution of 100 parts maleic acid / acrylic modified polyolefin resin (Nippon Paper Chemical Co., Ltd. aurolene) in 200 parts toluene. Dissolved. Thereafter, 20 parts of water was added at once under stirring of the anchor (rotation speed: 60 rpm) to confirm phase inversion. Stirring was performed for 30 minutes after phase inversion, and 250 parts of water was added to obtain an emulsified dispersion. Thereafter, toluene was distilled off under reduced pressure to obtain a milky white emulsion having a solid content of 30% and an average particle size of 0.8 μm.

[Primer test]
Primer tests were performed on the emulsions obtained in the above Examples and Comparative Examples. That is, after wiping an ultra-high-rigidity polypropylene plate that has not been surface-treated with isopropanol, it was applied to a dry film thickness of 10 μm and dried at 80 ° C. for 20 minutes. Next, a two-pack type top coat white coating was applied so that the dry film thickness was 40 μm, and allowed to stand at room temperature for 15 minutes, and then baked at 80 ° C. The test piece was allowed to stand at room temperature for 3 days, and then the following evaluation was performed. The results are shown in the table.

[Adhesiveness]
On the coated surface, 100 grids reaching the substrate at 1 mm intervals were made, and a cellophane adhesive tape was stuck on the coated surface and peeled off in the 180-degree direction to show the number of grids on which the coating film remained.

[Hot water resistance]
The test piece was immersed in warm water at 40 ° C. for 240 hours, the state of the coating film was visually observed, and then the adhesion was examined by the cross-cut test.

The polyolefin resin emulsion obtained by the present invention can be used as a paint, primer, ink, adhesive, or sealing resin. Moreover, it is also possible to mix | blend and use resin, such as aqueous acryl, urethane, and polyester.

Claims (3)

A method for producing a polyolefin resin emulsion,
In the surfactant phase containing surfactant, water and polyhydric alcohol in a ratio (however, weight ratio) within the range of surfactant / polyhydric alcohol / water = 10/1 to 30/15 to 45, Adding a polyolefin-based resin solution to form an O / D type gel emulsion in which the continuous phase is a surfactant phase;
A method for producing a polyolefin resin emulsion, comprising: adding water to the gel emulsion to change the continuous phase from a surfactant phase to an aqueous phase to obtain an O / W emulsion.   The method for producing a polyolefin resin emulsion according to claim 1, wherein the surfactant is used in an amount of 1 to 15% by weight based on the polyolefin resin. A polyolefin resin emulsion obtained by the production method according to claim 1 or 2, wherein the emulsion droplets have an average particle diameter of 0.1 to 5 µm.