JPH08108431A - Treatment of surface of polyolefin molding material and production of molding - Google Patents

Abstract

PURPOSE: To provide a polyolefin molding material improved in surface characteristics such as coating film adherence and adhesiveness, and provide also a molding consisting of the material. CONSTITUTION: A method of treating the surface of polyolefin molding material comprises exposing a powdery or granular polyolefin molding material in a gas having a boron partial pressure of 0.1-13% to modify its surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a polyolefin molding material having improved surface properties such as coating film adhesion and adhesion.

[0002]

2. Description of the Related Art Polyolefins are widely used in a wide variety of fields. For example, when they are used as automobile parts, they are usually painted, and when they are laminated with other base materials, adhesives and the like are used. Glue with. However, since polyolefin does not have a polar group in its structure, the adhesiveness of the paint is weak when attempting to paint, and the adhesiveness to the adhesive is weak when attempting to adhere. In order to improve the coating film adhesion and adhesiveness, surface modification such as applying a primer or plasma treatment after washing the surface of the polyolefin molded body with trichloroethane vapor has been performed. .

However, in the trichloroethane vapor cleaning, restrictions on the use of trichloroethane have been strengthened due to the fear of the vapor having an effect on the environment. Further, not only the primer application is expensive, but also the number of coating steps is increased and the coating cost is high. There is a drawback that Further, in the plasma processing method, an expensive apparatus has to be used, and it has been difficult to uniformly process a compact having a complicated shape or a large size.

In order to omit these treatments, many methods for improving the paintability of polyolefin have been proposed in recent years. For example, JP-A-3-157168 and the like describe that a composition obtained by adding a diene polymer having a hydroxyl group at a terminal to an elastomer-containing polyolefin has improved adhesiveness with a coating material. In addition, JP-A-4-
No. 103640 proposes a composition in which a hydroxyl group-containing ethylene copolymer and a carboxyl group-containing ethylene copolymer are added to an elastomer-containing polyolefin. However, with these compositions, not only the adhesiveness with paints is not yet sufficient, but also the deterioration of physical properties due to their addition is inevitable.

On the other hand, it is well known that the surface of a synthetic polymer film is modified with fluorine gas, but in this case,
This is a treatment for imparting water repellency by substituting hydrogen atoms on the film surface with fluorine atoms, and is rather a treatment for lowering paintability. Further, JP-A-3-126734 describes that the wettability of the surface of a molded article is improved by treating with a mixed gas of fluorine and oxygen or fluorine, oxygen and an inert gas. However, it has been shown that treatment with a high concentration of fluorine gas causes deterioration of surface wettability.

[0006]

SUMMARY OF THE INVENTION According to the present invention, while maintaining moldability and mechanical strength, coating adhesion is improved to such an extent that trichloroethane cleaning and primer treatment can be omitted, and the coating is uniformly modified. It is an object of the present invention to provide a polyolefin molding material having a uniform coating film adhesion that can be applied to a molded product having a complicated shape.

[0007]

[Means for Solving the Problems]

[Summary of the Invention] The present invention, in order to solve the above problems,
It has been found that the above-mentioned problems can be achieved by subjecting a polyolefin molding material to a specific surface treatment, rather than a molded body, and completed.

That is, the present invention discloses that "a powdery or granular polyolefin molding material is exposed to a gas having a fluorine partial pressure of 0.1 to 13% to modify the surface of the molding material. A method for surface treatment of a characteristic polyolefin molding material,
And a method for producing a molded body characterized by molding the treated molding material. "

[Detailed Description of the Invention] Polyolefin molding material The above-mentioned polyolefin molding material is a powdery or granular olefin polymer or a composition thereof which is generally used for molding. Here, the powdery or granular form is a powdery or granular form that is usually produced by polymerization, or a granular form that is easy to provide for molding through steps such as granulation or sheeting and then cutting. Means This olefin polymer is a homopolymer of α-olefin, a copolymer of α-olefins or a copolymer with other unsaturated monomer having α-olefin as a main constituent component, As specific olefins, for example, olefins having about 2 to 12 carbon atoms such as ethylene, propylene, butene-1, 3-methylpentene-1, 4-methylpentene-1, hexene-1, octene-1 are suitable. Is.

Other unsaturated monomers include, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylic acid, maleic anhydride or derivatives thereof; vinyl such as vinyl acetate and vinyl butyrate. Esters; unsaturated aromatic monomers such as styrene, methylstyrene and divinylbenzene; vinyltrimethoxysilane, γ-
Examples thereof include vinylsilane such as methacryloxypropyltrimethoxysilane. The content of the other unsaturated monomer in the olefin polymer may be in the range where α-olefin is the main component unless the effects of the present invention are significantly impaired, but is generally 30% by weight or less, and particularly 15% by weight or less. It is preferably less than or equal to weight%.

Among them, preferred olefin polymers are
They are ethylene-based polymers and propylene-based polymers. As the ethylene polymer, a low density ethylene homopolymer produced by a high pressure method, a copolymer containing ethylene as a main component and vinyl acetate, acrylic acid, acrylate, methacrylic acid, methacrylate, etc .; High-density ethylene homopolymer produced by, ethylene and propylene containing ethylene as a main component, butene-1, and hexene-
1, copolymers with other α-olefins such as octene-1, and the like. The copolymer is not limited to a binary copolymer,
It may be a ternary or higher copolymer.

As the propylene-based polymer, in addition to a propylene homopolymer, a copolymer of propylene containing propylene as a main component and another α-olefin such as ethylene, butene-1, and hexene-1. Etc. The copolymer is not limited to a binary copolymer, and may be a ternary or higher copolymer, and may be any copolymer type such as block, random or graft.

Further, the content of the ethylene-based copolymer and the propylene-based copolymer in the range not significantly impairing the effects of the present invention, for example, 30% by weight or less, particularly 15% by weight.
Other unsaturated monomers mentioned above may be included. These polyolefins may be used in combination of two or more.

In particular, considering the use as a member for automobiles, it is required that the moldability and the mechanical strength are high, so that the MFR (melt flow rate measured according to ASTM-D1238) is 0. 0.01 to 200 g
/ 10 minutes, preferably 0.1 to 100 g / 10 minutes, particularly preferably 0.5 to 50 g / 10 minutes, and JIS-K
Bending elastic modulus measured according to 7203 is 1,000 to
25,000 kg / cm ² , preferably 2,000-2
Polyolefins in the range of 10,000 kg / cm ² are preferably used. Among them, ethylene-propylene copolymers are preferable, and particularly, the ethylene content is 1 to 40% by weight.
The block copolymer of is preferable.

The polyolefin molding material may optionally contain components other than the above components unless the effects of the present invention are significantly impaired. Examples of such optional components include elastomer components and other resin components, antioxidants, heat stabilizers, light stabilizers, colorants, antistatic agents, conductive agents, dispersants, and molecular weights for the purpose of adjusting physical properties and appearance. Regulator, cross-linking agent, cross-linking aid, nucleating agent, filler, lubricant, foaming agent, flame retardant, flame retardant aid, processing aid, neutralizing agent, heavy metal deactivator,
A plasticizer etc. can be mentioned.

Above all, it is preferable to contain the elastomer component in an amount of 15 to 80% by weight, further 15 to 75% by weight, and especially 15 to 70% by weight, since impact resistance and flexibility can be imparted without causing blocking. As the elastomer component, α-such as ethylene, propylene, butene-1, and pentene-1 from the viewpoint of compatibility with the polyolefin.
Olefin copolymers or α-olefin and diene copolymers are preferred. These copolymers are JIS-K6
The initial elastic modulus measured according to 301 is 400 kg / c
It is preferably amorphous or low crystalline with m ² or less, particularly 200 kg / cm ² or less. Specifically, ethylene-propylene copolymer rubbers, ethylene-propylene-diene copolymer rubbers, ethylene-butene-1 copolymer rubbers, and other ethylene-based copolymer rubbers, particularly ethylene-propylene-based copolymer rubbers. Is preferred.

Gas with a partial pressure of fluorine of 0.1 to 13% The gas used for surface-treating the polyolefin molding material in the present invention has a partial pressure of fluorine of 0 when the total gas pressure is 100%. 0.1 to 13%, preferably 0.1 to 10
%, Particularly preferably 0.1 to 8%, that is, a gas containing fluorine with a low partial pressure. When the partial pressure of fluorine is less than this range, it is difficult to sufficiently improve the surface properties such as coating adhesion and adhesiveness. On the other hand, when it exceeds this range, the treated surface becomes water repellent and the surface properties are deteriorated. It's not good because it happens.

This gas may have any composition as long as the partial pressure of fluorine is within the above range, but an inert gas which may contain oxygen and a mixed gas of fluorine are preferable. A suitable partial pressure of oxygen is selected within the range of 80% or less. Further, as the inert gas, helium, neon,
Gases of Group 0 elements of the Periodic Table of Elements such as argon, nitrogen, carbon dioxide, etc. are preferably used. The mixed gas may be mixed with other gas including dry air.

Conditions for surface treatment: A polyolefin molding material having a fluorine partial pressure of 0.1 to 13 is used.
In order to surface-treat the molding material by exposing it to a gas having a concentration of 100%, it is generally preferable to fill the molding material in a sealed container equipped with a stirring mechanism and to perform stirring while exposing to the gas. . The treatment time depends on the partial pressure of fluorine, the amount of the molding material to be treated, the treatment device, etc., but is in a range where the treatment effect is exhibited without water repellency, that is, generally 0.01 to 60 minutes, preferably It is 0.1 to 30 minutes, particularly preferably 0.5 to 20 minutes. In addition, the treatment temperature is generally appropriately selected from the range of not less than the embrittlement temperature of the polyolefin specified by JIS-K7216 and not more than the melting temperature, preferably not more than the heat distortion temperature specified by JIS-K7207.

Molding of Molded Article The surface-treated powdery or granular polyolefin molding material obtained by the above-mentioned method is kneaded with an optional melt-kneading machine by a usual melt-kneading machine, and preferably molded. It is granulated and molded by various molding machines to obtain a molded product having a mold shape, a film shape, a sheet shape, a plate shape or the like. At this time, the molding material optionally mixed with optional components may be directly molded by various molding machines. As the molding method, injection molding, compression molding,
Extrusion molding (sheet molding, blow molding, pipe molding, etc.),
Usual molding methods such as calender molding and foam molding can be applied, but among them, injection molding is in close contact with the coated molded article, and is preferable in terms of the effect of coating property. In particular, when the molded product is a member for automobiles, the coatability is improved while maintaining the moldability and mechanical strength, which is particularly effective.

Coating of Molded Article In order to obtain an automobile member or the like coated with the surface-treated polyolefin molding material obtained by the method of the present invention, the molded article obtained by the above-mentioned molding method is used. The paint is applied to the surface of to form a coating film on the surface. At this time,
The paint can be applied directly. As a coating method, a construction method in which the primer coating is removed from the conventional coating process can be adopted. Also, the plasma treatment process can be omitted. An auxiliary surface treatment such as degreasing treatment before coating the coating material may be performed.

The degreasing treatment is generally carried out immediately before coating in order to remove dusts, process oils and the like that inevitably adhere to the surface of the molded product. Specifically, an organic solvent solution or its vapor,
A cleaning method using water, water vapor, acid, alkali solution, surfactant or the like is adopted. As a means for applying the coating material, conventionally known coating methods such as spray coating, brush coating, roller coating and the like can be adopted.

As the paint, generally-used paints such as acrylic, epoxy, polyester, urethane, alkyd, melamine, and fluorine can be used. Of these, acrylic, polyester, urethane and melamine paints are preferably used.

[0024]

The present invention will be further described below with reference to specific examples. Examples 1 to 6 and Comparative Examples 1 to 5 <Constituent Components of Sample> As an olefin resin, 4500
J (Propylene homopolymer powder manufactured by Mitsubishi Chemical Corporation, MFR9
g / 10 minutes), 7400AG (Propylene-ethylene block copolymer powder manufactured by the same company, MFR 7 g / 10 minutes), 6
500J (Propylene-ethylene random copolymer powder manufactured by the same company, MFR 10g / 10 minutes), F100 (Ethylene homopolymer pellets manufactured by the same company, MFR 0.4g / 10 minutes)
4 types were used. In addition, EP57P (ethylene-propylene-diene copolymer rubber manufactured by Japan Synthetic Rubber Co., Ltd., iodine value 15, Mooney viscosity 88) was used as the olefin elastomer. Further, as a cross-linking agent, Perhexin 25B (2,5-dimethyl-2,5-di (t-butylperoxy) hexin-3 manufactured by NOF CORPORATION, half-life of 145
Was used for 1.7 hours).

<Surface Treatment with Fluorine-Containing Gas> For each of the powders or pellets of the above-mentioned olefin resin, 150 g of the powder or pellet was placed in a closed reactor having resistance to fluorine, evacuated, and then fluorine, oxygen and nitrogen were added. The mixed gas having the partial pressure shown in Table 1 is introduced to adjust the internal pressure to 10
It was set to 1,080 Pa (760 torr). After the temperature in the container was set to 23 ° C. and the treatment was performed for 5 minutes, the mixed gas was evacuated and nitrogen was introduced to return the internal pressure to the atmospheric pressure to obtain each surface-treated olefin resin powder or pellet. The resin used in the comparative example was not treated.

<Molding> The compounding composition shown in Table 1 was rotated by a Labo Plastomill at a set temperature of 200 ° C. to rotate at 60 rpm.
Melt and knead for 4 minutes at 120 ° C. by hot pressing at 200 ° C.
A flat plate sample of mm × 120 mm × 2 mm was molded.

<Evaluation of coatability> The obtained flat plate sample was degreased by washing with a 0.15% by weight aqueous solution of Mama Lemon (a household neutral detergent manufactured by Lion Corporation) for 3 minutes and then with steam for 6 minutes.
After wiping off water on the surface, the sample was left for 12 hours at room temperature to obtain a coated sample. The following two-component acrylic urethane-based paint was spray-coated with an air spray gun to a coating thickness of about 40 μm, and then 80
It was baked and dried at 30 ° C. for 30 minutes. Paint 1: Superior FII White (Nippon Paint Co., Ltd.) Paint 2: Superior FII Silver Metallic (Nippon Paint Co., Ltd.) Paint 3: Nippon Bee Chemical Co., Ltd. Black

The coating film adhesion was evaluated in the cross-cut test as follows. Vertical and horizontal 1 orthogonal to the sample surface with a single-edged razor
One parallel line was drawn at 1 mm intervals to make 100 grids. Cellophane adhesive tape (JIS-Z
1522) was sufficiently pressure-bonded, kept at an angle of about 30 degrees with the coating surface, and peeled off at once in front, the state of the part surrounded by the grids was observed, and the number of grids that did not peel was recorded. The results are shown in Table 1.

[0029]

[Table 1]

[0030]

INDUSTRIAL APPLICABILITY According to the present invention, a molding material having improved surface properties such as coating film adhesion and adhesiveness, and thus a molded product thereof, can be obtained. This is particularly useful for automobile parts.

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Claims (6)

[Claims] 1. A polyolefin characterized by exposing a powdery or granular polyolefin molding material to a gas having a fluorine partial pressure of 0.1 to 13% to modify the surface of the molding material. Surface treatment method for molding material. 2. The surface treatment method for a polyolefin molding material according to claim 1, wherein the polyolefin is an ethylene polymer or a propylene polymer. 3. The polyolefin has an elastomer component of 1
The surface treatment method for a polyolefin molding material according to claim 1, which contains 5 to 80% by weight. 4. The surface treatment method for a polyolefin molding material according to claim 4, wherein the elastomer component is an ethylene copolymer rubber. 5. The surface treatment method for a polyolefin molding material according to claim 1, wherein the gas is a mixed gas of an inert gas which may contain oxygen and fluorine. 6. A powdery or granular polyolefin molding material is exposed to a gas having a fluorine partial pressure of 0.1 to 13% to modify the surface of the molding material, which is then molded. A method for producing a molded article, which is characterized in that