JP2602153B2 - Aqueous dispersion for resin molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous dispersion for a resin molded article, and more particularly to an aqueous dispersion for a resin molded article suitable for a primer or a paint used for a polyolefin resin molded article and a method for producing the same.

[0002]

2. Description of the Related Art Polyolefin resins such as polypropylene are widely used as plastics for home electric appliances and automobile parts because of their excellent resin properties and low cost. In this case, since the polyolefin resin is a non-polar resin, it is difficult to apply or adhere to a molded article of the resin. It is common to undercoat.

However, since chlorinated polyolefins are used by dissolving them in aromatic organic solvents such as toluene and xylene which are harmful to the human body, there is a problem that safety and environmental problems arise. Therefore, a method of converting a chlorinated polyolefin into an aqueous dispersion has been attempted (for example, JP-A Nos. 1-153778 and 1-2565).
No. 56 and No. 2,284,973), however, also in this method, it is difficult to completely eliminate the use of an aromatic organic solvent, and there is a defect that the obtained coating film has poor light resistance.

On the other hand, a method for producing an aqueous dispersion of a modified polyolefin as a primer has been attempted (for example, Japanese Patent Publication No. 42175/1972 and 5842207/1983).
No. 59-28217, JP-A-59-47244.
Nos. JP-A-1-256549, JP-A-286724 and JP-A-39350). However, since the modified polyolefin resin contains a large amount of other components, the adhesion of the coated film is deteriorated, and the use of an aromatic organic solvent cannot be eliminated at all, and the modified polyolefin resin contains the organic solvent. Since it is converted into an aqueous dispersion as it is, there is a disadvantage that a post-step for removing the organic solvent is required.

By the way, the present inventors have already proposed an aqueous dispersion composition containing a modified polyolefin and a polyol as main components without using an aromatic organic solvent and having excellent performance as a primer. Has been paid. However, the composition has a drawback that it is necessary to adjust the content of the polyol or the like depending on the use to be used, and the composition is complicated.

[0006]

The present inventors have conducted intensive studies in order to solve the above-mentioned drawbacks. As a result, when a specific modified polyolefin, a surfactant and a basic substance are dispersed in water, The inventors have found that good results can be obtained as primers and the like, and have reached the present invention.

Accordingly, it is an object of the present invention to improve the coating properties and adhesion of a resin molded product by forming an excellent coating film as a primer without using an organic solvent at all and easy to handle. To provide an aqueous dispersion for a resin molded article (referred to as an aqueous dispersion).

[0008]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
A carboxyl group-containing modified propylene-α-olefin copolymer having a melting point of 120 ° C. or less and an acid value of 10 to 150 and a number average molecular weight of 2,000 to 20,000, and an HLB of 9 to 16 A carboxyl group-modified propylene-α-olefin is used as a nonionic surfactant.
An aqueous dispersion for a resin molded article comprising 1 to 25% by weight of a basic substance and 0.4 chemical equivalent or more relative to the carboxyl group in a water and a method for producing the same. Achieved.

The carboxyl group-containing modified propylene {α} olefin copolymer used in the present invention is propylene
The α-olefin copolymer can be easily produced by graft copolymerizing a polymerizable double bond and a monomer having a carboxyl group or an acid anhydride having a polymerizable double bond. The propylene {α} olefin copolymer can be easily obtained by random or block copolymerization of propylene and α─ olefin, but in the present invention, a random copolymer having a low melting point may be used. preferable.

The α─ olefin is not particularly limited and can be appropriately selected from known ones. Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene and the like. Among these, it is particularly preferable to use ethylene or 1-butene from the viewpoint of the physical properties of the obtained resin. These may be used in combination of two or more.

The proportion of the propylene component in the above copolymer is preferably 55 to 85 mol%. 55 mol%
When the content is below, the adhesiveness of the coating when the aqueous dispersion is used as a primer or the like for a polyolefin resin molded article is poor, and when it is 85 mol% or more, the melting point of the copolymer becomes high and the aqueous dispersion is produced. It becomes difficult.

Examples of monomers having a polymerizable double bond and a carboxyl group or acid anhydrides having a polymerizable double bond include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, Examples thereof include citraconic acid, allylsuccinic acid, mesaconic acid, and aconitic acid.

These monomers are preferably graft-copolymerized so that the resulting copolymer has an acid value of 10 to 150. When the acid value is 10 or less, it is difficult to produce an aqueous dispersion, and when it is 150 or more, the water resistance of the obtained aqueous dispersion is deteriorated. Particularly preferred acid values are
It is in the range of 30 to 120. Here, the acid value is 1 g of resin.
The amount of potassium hydroxide (KOH) required to neutralize is a numerical value expressed in mg.

It is easy to graft copolymerize a monomer having a polymerizable double bond and a carboxyl group or an acid anhydride having a polymerizable double bond to a propylene {α} olefin copolymer by using a known polymerization method. Can be done. As a preferable graft copolymerization method, a method in which a propylene {α} olefin copolymer is heated and melted at a temperature equal to or higher than the melting point, then the above-described monomer is added, and the graft copolymerization is performed in the presence of a radical generator.

Specifically, a propylene {α} olefin copolymer is added to a reaction vessel equipped with a powerful stirrer (a Banbury mixer, kneader or extruder may be used), and a temperature of about 150 to 300 ° C. The monomer and the radical generator are added within the range, and the polymerization reaction is performed by stirring, and the obtained product is pelletized by a known method.

The radical generator can be appropriately selected from known radical generators. Preferred radical generators include organic peroxides. Specific examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, 2,5-dimethyl 2,5-di (t-butylperoxy) hexine 3, and di-t}. Butyl peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, cumene hydroperoxide and the like. These are appropriately selected and used depending on the reaction temperature.

The number average molecular weight of the modified propylene {α} olefin copolymer is preferably in the range of 2,000 to 20,000. When the molecular weight is 2,000 or less, although an aqueous dispersion can be produced, the cohesive force of the copolymer is weak, so that the adhesion between the coating film and the polyolefin resin molded product when used as a primer or the like is deteriorated. I do. Also,
If it exceeds 20,000, an aqueous dispersion cannot be produced. The number average molecular weight can be easily measured using gel permeation chromatography (GPC).

The modified propylene {α} olefin copolymer preferably has a melting point of 120 ° C. or lower. When a material having a temperature of 120 ° C. or higher is used, an aqueous dispersion cannot be produced. The preferred range of the melting point is 9
0-120 ° C. Here, the melting point of the polymer can be easily measured using a differential scanning calorimeter (DSC).

The nonionic surfactant used in the present invention comprises:
From the viewpoint of maintaining the stability of the aqueous dispersion during and after the production and improving the film forming property of forming a film by applying to a resin molded product, the nonionic surfactant having an HLB of 9 to 16 is used. It is preferably an agent. When a nonionic surfactant having an HLB of 9 or less or 16 or more is used,
If an aqueous dispersion cannot or cannot be obtained,
The aqueous dispersion has poor stability. Where HLB
Is an index indicating the ratio between the hydrophilic group and the hydrophobic group, and is represented by the following formula. HLB = 20 × weight of hydrophilic group / molecular weight of surfactant

Specific examples of the nonionic surfactant include:
Examples thereof include polyoxyethylene alkyl esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, sorbitan alkyl esters, and polyglycerin esters. These may be used in combination. The amount of the nonionic surfactant used is preferably from 1 to 25% by weight, particularly preferably from 3 to 15% by weight, based on the modified propylene-α-olefin copolymer. The amount of the above surfactant is less than 1% by weight
And the stability of the aqueous dispersion becomes poor, exceeding 25% by weight.
In addition, the adhesion and water resistance of the coating film deteriorate.

Incidentally, an appropriate amount of an anionic surfactant or a fluorine-based surfactant may be used in combination. In the present invention, a basic substance is used from the viewpoint of maintaining good stability of the aqueous dispersion. The basic substance can be appropriately selected and used from known basic substances.

Specific examples of the basic substance include sodium hydroxide, potassium hydroxide, ammonia, methylamine,
Ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N 、 methyldiethanolamine, dimethylamine, diethylamine, triethylamine, N, N─dimethylethanolamine, 2
{Dimethylamino} 2-methyl-1-propanol, 2
{Amino-2-methyl} propanol, morpholine and the like. Among them, ethanolamine,
It is preferable to use an amine having a hydroxyl group, such as 2-amino-2-methyl-1-propanol.

The amount of the basic substance to be used is preferably at least 0.4 chemical equivalent to the carboxyl group of the carboxyl group-containing modified propylene {α} olefin copolymer used, and particularly preferably from 0.4 to 1 equivalent. It is preferably in the range of 0.5 chemical equivalents, and most preferably in the range of 0.5 to 1.2 chemical equivalents. When the amount is less than 0.4 chemical equivalent, the stability of the obtained aqueous dispersion is poor.

The aqueous dispersion for a resin molded article of the present invention is prepared by melting a carboxyl group-containing modified propylene {α} olefin copolymer and then adding a nonionic surfactant and a basic substance to the composition. The polymer can be easily produced by gradually adding water and dispersing in water so that the temperature is maintained at or above the melting point of the polymer.

The heating temperature may be higher than the melting point, but is preferably in the range of 90 to 120 ° C., and more preferably under pressure.
On the other hand, the temperature of the water to be added is preferably in the range of 80 to 98 ° C. As the amount of water added increases, the viscosity of the system increases rapidly, and upon further addition of water, the phase transitions from water-in-oil (W / O) to oil-in-water (O / W),
After that, it becomes an aqueous dispersion which can be optionally diluted with water.

The above operation can be easily performed using a colloid mill, a reactor (a kettle) equipped with a stirrer, or a kneader. From the viewpoint of efficient stirring, the stirrer of the device is preferably powerful. Modified propylene {α}
The solvent may be added to the olefin copolymer to perform the above operation, and the solvent may be distilled off in a later step. However, it is preferable to perform the operation without a solvent from the viewpoint of preventing environmental pollution and the like.

The aqueous dispersion of the present invention can be used as it is or by adding a pigment or other aqueous resin, as a primer for coating or bonding a resin molded product. As the resin molded product, a polyolefin-based resin molded product is particularly preferable from the viewpoint of adhesiveness.

As a coating method when used as a primer, a known roll coating method, spray coating method, brush coating method, or the like can be used. The aqueous dispersion of the present invention can also be used as a component of a top coat, a coating agent for a polyolefin film, a resin component for an ink, or a component for a resin molded product, particularly an adhesive for a polyolefin resin molded product.

[0029]

The aqueous dispersion for resin molded articles of the present invention is easy to handle and, when used as a primer or an adhesive component for resin molded articles, improves the paintability and adhesion of the resin molded articles. can do. In addition, the production method of the present invention does not use an organic solvent at all, and therefore does not pollute the environment and is a production method with sufficient safety.

[0030]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Modified propylene containing a carboxyl group
Production example of {α} olefin copolymer In a four-necked flask equipped with a stirrer, a condenser and a dropping funnel, propylene / butene copolymer (containing 75 mol% of propylene as a component) 300
g, and heated and melted, 25 g of maleic anhydride and 5 g of dicumyl peroxide were added dropwise over 3 hours while stirring while maintaining the temperature of the system at 180 ° C., and the reaction was further continued for 3 hours.

After the completion of the reaction, the obtained reaction product is poured into a large amount of acetone, and purified to obtain a carboxyl-containing modified propylene / butene copolymer having an acid value of 55 with the anhydride ring opened. A polymer was obtained. As measured by GPC, the number average molecular weight of the obtained copolymer was 8,000
It was 0. The melting point measured by DSC is 95
° C.

The number average molecular weight is determined by dissolving a sample in tetrahydrofuran (THF) and subjecting the sample to HLC４０ at 40 ° C.
It was determined from a value measured using 8020 (trade name of GPC manufactured by Tosoh Corporation) and a calibration curve prepared using a polystyrene standard sample. The melting point was measured using a DSC 20 (trade name of DSC manufactured by Seiko Instruments Inc.).

Production Example 2 Propylene-butene copolymer 3
Was replaced with a propylene / ethylene copolymer (containing 70 mol% of a propylene component), the amount of maleic anhydride used was changed to 40 g, and dicumyl peroxide 5
g was replaced with 8 g of di-t-butyl peroxide,
A modified propylene-ethylene copolymer containing a carboxyl group and having an acid value of 120 was obtained in exactly the same manner as in Production Example 1. When the number average molecular weight and the melting point of the obtained copolymer were measured in exactly the same manner as in Production Example 1, each was 6,000.
And 98 ° C.

Production Example 3 Propylene-butene copolymer 3
The same procedure as in Production Example 1 was repeated except that 00 g was replaced with propylene (ethylene copolymer (containing 50 mol% of propylene component)). A butene copolymer was obtained. The number average molecular weight and melting point of the obtained copolymer were measured in exactly the same manner as in Production Example 1 and found to be 24,000 and 125 ° C., respectively.

Embodiment 1 Production of Aqueous Dispersion 100 g of the modified copolymer obtained in Production Example 1 was charged into a 1-liter flask equipped with a stirrer, and was heated and melted.
B is 14.1 nonionic surfactant (Nonion NS-
212: 12 g of Nippon Yushi Co., Ltd.) was added, and then ethanolamine (0.7 chemical equivalent) was added. The obtained composition is kept at 100 ° C., and water 3 at 90 ° C.
00g was added little by little with vigorous stirring to obtain a milky white aqueous dispersion.

Evaluation Test 1. Stability The above aqueous dispersion was left for one month, and the stability of the dispersion was visually evaluated. The results are as shown in Table 1.

2. Coating Film Test The above aqueous dispersion was applied to a polypropylene resin plate by using a spray, dried at 80 ° C. for 15 minutes, and then a two-pack type urethane top coat was applied to the coated surface of the plate.
Leave at room temperature for 0 minutes, then use a hot air drier at 80 ° C.
For 30 minutes and left for 1 day to obtain a test piece.

Adhesion Cuts reaching the substrate were made in the vertical and horizontal directions at intervals of 1 mm using a cutter so that the number of grids was 100 on the surface of the coating film of the obtained test specimen. After adhering the cellophane adhesive tape on the surface of the obtained grid-like cut, the film was peeled off at an angle of 180 ° with respect to the coating film surface, and the number of eyes remaining without peeling the coating film And the adhesion was evaluated. The results are as shown in Table 1.

Gasoline resistance A cut was made on the surface of the obtained test piece by using a cutter on the surface of the coating film, and then the coating film was visually immersed in regular gasoline for 4 hours. Observed and evaluated. The results are as shown in Table 1.

[0041]

[Table 1]

Embodiments 2 to 5 An aqueous dispersion was obtained in exactly the same manner as in Example 1 except that the composition was changed as shown in Table 2.
An evaluation test was performed in exactly the same manner as in Example 1. The results are as shown in Table 1.

Comparative Examples 1-2. An aqueous dispersion was obtained in exactly the same manner as in Example 1 except that the composition was changed as shown in Table 2.
An evaluation test was performed in exactly the same manner as in Example 1. The results are as shown in Table 1.

[0044]

[Table 2]

Claims (3)

(57) [Claims] (1) a melting point of 120 ° C. or less and an acid value of 10 to 1;
50 and a number average molecular weight of 2,000 to 20,
Carboxyl group-containing modified propylene-α-
An olefin copolymer and a non-ionic surfactant having an HLB of 9 to 16 are modified propylene containing a carboxyl group.
-An aqueous dispersion for a resin molded product obtained by dispersing a basic substance in water in an amount of 1 to 25% by weight based on the α-olefin copolymer and 0.4 or more chemical equivalents based on the carboxyl group. 2. A modified propylene-α-containing carboxyl group.
The aqueous dispersion for a resin molded product according to claim 1, wherein the propylene component in the olefin copolymer is 55 to 85 mol%. 3. The melting point is 120 ° C. or less and the acid value is 10-1.
50 and a number average molecular weight of 2,000 to 20,
Carboxyl group-containing modified propylene-α-
After melting the olefin copolymer, a nonionic surfactant having an HLB of 9 to 16 is modified with a carboxyl group-containing modified resin.
1 to 25 times with respect to the propylene-α-olefin copolymer
%, And a composition obtained by adding at least 0.4 basic chemical equivalent to the carboxyl group is dispersed in water by adding water at a temperature not lower than the melting point of the copolymer. A method for producing an aqueous dispersion for a resin molded product.