JP2009001764A - Primer composition, ordinary temperature surface-hardening method, and surface-treated molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a primer composition that is used for coating a surface of an object to be coated; to provide an ordinary temperature surface-hardening method by using the primer composition, in which the object to be coated is surface-treated by using an exclusive primer composition to enhance adhesion and then is surface-hardened by using the ordinary temperature surface-hardening coating agent; and to provide a surface-treated molded product such as a synthetic resin molded product or a metal molded product coated with the hardened film. <P>SOLUTION: A resin obtained by modifying a specific amorphous polypropylene resin with maleic anhydride is used as the surface treating primer applied to a non-adherent object to be coated. A specific inorganic-organic composite coating agent surface-hardened at an ordinary temperature is used. The surface treated molded product is obtained by using the resin primer and the coating agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a primer composition for coating a surface of a coated body and a method using the primer composition. In order to improve adhesion to the coated body, the primer treatment is performed using a dedicated primer composition, and the surface is treated at room temperature. The present invention relates to surface curing using a curing coating agent, and further to providing a surface processed molded product such as a synthetic resin molded product or a metal molded product coated with the cured film.

Environmentally friendly non-chlorine modified polypropylene primer has been proposed as a primer for painting and surface coating to improve adhesion to synthetic resin moldings such as difficult-to-adhere polypropylene and mirror-finished metal moldings such as stainless steel .
For example, Patent Document 1 proposes a primer that has no stickiness of the coating film, is excellent in low-temperature heat sealability, and exhibits good adhesion to polyolefin.
However, the basic structure of this polypropylene-based elastomer is an elastomer structure that has a segment of repeating units with some crystallinity, so that the adhesion boiling test (water resistance) for mirror-finished metal is insufficient. There was a problem.
Patent Document 2 proposes a primer for coating polyolefin resin.
Since the basic structure of the polymer in this case also has crystallinity derived from isotactic chains, there are problems such as insufficient adhesion to mirror-finished metal in boiling tests (water resistance). It was.

In general, synthetic resins such as polyolefin resins, (meth) acrylic resins, and polycarbonates are widely used in various applications because of their features such as easy moldability, light weight, and impact resistance.
However, since the surface of the synthetic resin is easily scratched and easily charged, the appearance is remarkably deteriorated due to scratches or adhering dust. Therefore, a method of providing a cured film on the surface has been proposed.
For example, Patent Document 3 proposes a surface coating mainly composed of a polymerizable compound having a (meth) acryloyloxy group or a silane-based thermopolymerizable compound. Due to the photopolymerization reaction by irradiation with active energy rays such as ultraviolet rays and electron beams, there was a problem that expensive ultraviolet rays irradiation and a heating device were required.

JP 2001-311036 A JP 2007-002117 A JP 09-048950 A

  The present invention is a method for surface-coating a coated body made under such circumstances. In order to improve adhesion to the coated body, the surface treatment is performed at room temperature by applying a primer treatment with a dedicated primer composition. The object of the present invention is to provide a surface-treated molded product such as a synthetic resin molded product or a metal molded product coated with the cured film by surface curing using a coating agent.

As a result of intensive studies to achieve the above-mentioned object, the present inventors have applied a solvent-soluble product of a resin component obtained by modifying a specific amorphous polypropylene-based resin with maleic anhydride to a difficult-to-adhere coating. It has been found that the above problems can be solved by using as a primer composition to be treated and using a specific inorganic-organic composite coating agent that is surface-cured at room temperature.
That is, in the present invention, an amorphous polypropylene resin synthesized with a metallocene catalyst having a weight average molecular weight of 70,000 to 200,000 and a molecular weight distribution (Mw / Mn) of 5 or less was modified with maleic anhydride. Maleic anhydride-modified polypropylene resin having a maleic acid modification rate of 0.3 to 10.0% by weight and a weight average molecular weight of 40,000 to 150,000, alicyclic hydrocarbon and ester type Applying a primer composition comprising 75 to 85% by weight of a mixed solvent or an aromatic hydrocarbon and a ketone-based mixed solvent to a hard-to-adhere coating such as polypropylene, polyethylene terephthalate or polycarbonate, and inorganic-organic composite Mold coating agent forms an inorganic siloxane matrix with nanosilica and silane coupling agent, Those that sometimes form a hybrid cross-linked structure with organic functional groups, or those that are hydrolyzed and contain non-organic polymers, or based on a silicon resin with a terminal -SiOH type, acrylic modified, urethane modified, amide modified, The problem is solved by using a melamine-modified one.

The effect of the invention of claim 1 will be explained. By dissolving a resin modified with maleic anhydride in a mixed solvent with respect to an amorphous polypropylene resin, it is excellent in water resistance and further has adhesion and blocking resistance. A solvent-based primer for a difficult-to-adhere adhesive coating is provided.
According to the invention of claim 2, there is provided an environmentally-friendly water-based emulsion primer that does not contain a solvent for a hard-to-adhere coating having excellent water resistance and excellent adhesion and blocking resistance.
The effect of the invention of claim 3 will be explained. A simplified coating method in which room temperature surface curing is possible with the combination of the primer composition and the inorganic-organic composite coating agent, and no expensive ultraviolet irradiation or heating device is required. Is provided.
If the effect of invention of Claim 4 is demonstrated, the hybrid coating cured film which does not produce a crack even if it will apply thickly will be provided.
According to the invention of claim 5, a cured coating film having good hardness and weather resistance and good flexibility and film forming property is provided.
Further, the effect of the invention of claim 6 will be described. Polyalkenes such as polyethylene and polypropylene, which have been difficult-to-adhere coatings, polyolefin resins such as cyclopentene polymers and norbornene ring-opening polymers, PET and PEN, and the like. Surface processing such as polyester resin, (meth) acrylic resin, polystyrene resin, MS resin, AS resin, ABS resin, polycarbonate resin, cellulose acetate butyrate resin, or other synthetic resin or metal surface such as aluminum, stainless steel, silver, copper, etc. A molded article is provided.

The primer composition for pretreating the coating of the present invention comprises an amorphous polypropylene resin modified with maleic anhydride and an alicyclic hydrocarbon and ester mixed solvent or an aromatic hydrocarbon and ketone mixed solvent. It is characterized by comprising.
The amorphous polypropylene resin is obtained by copolymerizing propylene, ethylene, butene and other monomers.
The weight average molecular weight of the amorphous polypropylene resin is 70,000 to 200,000, preferably 70,000 to 150,000. If the weight average molecular weight is in the above range, maleic anhydride modification treatment is easy and a highly adhesive resin can be obtained. The molecular weight distribution (Mw / Mn) is 5 or less, preferably 4 or less, more preferably 3 or less. Blocking resistance improves because molecular weight distribution is 5 or less. The molecular weight distribution is a numerical value calculated from a weight average molecular weight (Mw) and a number average molecular weight (Mn) measured by gel permeation chromatography (GPC).
The intrinsic viscosity [η] of the amorphous polypropylene resin is preferably 0.7 to 10 dl / g. If it is the said range, coexistence of the adhesiveness of a resin composition and blocking resistance will be attained. From the above viewpoint, it is preferably 0.9 to 8 dl / g, and more preferably 1.2 to 7 dl / g.
The intrinsic viscosity [η] is measured using an Ubbelohde viscometer in 135 ° C. tetralin.
The polypropylene-based resin of the present invention is an amorphous polypropylene-based resin that does not have an elastomer structure with a segment of a repeating unit that is partially crystalline. By using the amorphous polypropylene resin, water resistance is improved along with the adhesiveness of the resin composition.
Suggested scanning calorimetry (DSC) can be used as a non-crystalline standard. In the temperature range of −100 to 200 ° C., a crystal melting peak with a crystal melting heat amount of 1 J / g or more and a crystallization heat amount of 1 J / g or more. It is preferred that none of the crystallization peaks are observed. The heat of crystal fusion and the heat of crystallization can be measured under the following conditions.
(I) About 5 mg of a sample is heated from room temperature to 200 ° C. at a temperature rising rate of 30 ° C./min, and then kept at 200 ° C. for 5 minutes.
(Ii) The temperature is decreased from 200 ° C. to −100 ° C. at a temperature decreasing rate of 10 ° C./min, and then kept at −100 ° C. for 5 minutes.
(Iii) The temperature is increased from −100 ° C. to 200 ° C. at a temperature increase rate of 10 ° C./min.
The peaks observed in the above (ii) and (iii) are a crystallization peak and a crystal melting peak, respectively. In the present invention, it is preferable that there is no peak of 1 J / g or more.

  In the present invention, it is preferable to use an amorphous polypropylene resin produced with a metallocene catalyst. By using an amorphous polypropylene resin synthesized with a metallocene catalyst, the blocking resistance of the resin composition is improved. Examples of the metallocene catalyst include, for example, JP-A-58-19309, JP-A-60-35005, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008. JP, JP 61-130314, JP 3-163088, JP 4-268307, JP 9-12790, JP 9-87313, JP 11-80233. And metallocene catalysts described in JP-A-10-508055 and the like.

In the present invention, a conventionally known technique can be used as a method of modifying an amorphous polypropylene resin with maleic anhydride, and the method is not particularly limited. For example, after melting an amorphous polypropylene resin, a method of adding an organic peroxide and maleic anhydride, or after dissolving an amorphous polypropylene resin in a solvent such as toluene or xylene, And a method of adding maleic anhydride. A twin-screw extruder used for acid modification and dynamic crosslinking of polyolefin elastomers can also be used, but from the viewpoint of increasing the addition reaction rate of maleic anhydride, special stirring that controls the reaction temperature with a heat medium It is preferable to use a reaction kettle with wings.
The molecular weight of the maleic anhydride-modified amorphous polypropylene resin has a weight average molecular weight of 40,000 to 150,000, preferably 70,000 to 120,000. If it is less than 40,000, the adhesion performance may be lowered, and if it exceeds 150,000, handling becomes difficult due to high viscosity. The maleation rate is 0.3 to 10% by weight, preferably 1 to 4% by weight. If the amount is less than 0.3% by weight, it is difficult to lower the adhesive performance and make it an aqueous emulsion. If the amount exceeds 10% by weight, it is difficult to handle due to high viscosity. In the present invention, the maleation rate means the ratio of maleic anhydride to the component (A) and / or the component (B). The melt viscosity is preferably 25,000 to 45,000 mPa · s at 185 ° C., more preferably 27,000 to 33,000 mPa · s. If it is less than 25,000 mPa · s, the adhesion performance may be lowered, and if it exceeds 45,000 mPa · s, handling becomes difficult. The acid value is preferably 5 to 20 mgKOH / g, more preferably 8 to 15 mgKOH / g. When it is less than 5 mgKOH / g, it is difficult to make an aqueous emulsion, and when it exceeds 2 OmgKOH / g, handling becomes difficult due to high viscosity.
A primer composition can be obtained by dissolving the maleic anhydride-modified amorphous polypropylene resin in an alicyclic hydrocarbon and ester mixed solvent or an aromatic hydrocarbon and ketone mixed solvent. As cycloaliphatic hydrocarbon solvents, cyclohexane, methylcyclohexane, etc., ester solvents, ethyl acetate, butyl acetate, etc., aromatic hydrocarbon solvents, toluene, xylene, etc., ketone solvents, Examples thereof include methyl ethyl ketone and methyl isobutyl ketone, and the mixing ratio of the mixed solvent is preferably 75 to 85% by weight. If it is less than 75% by weight, it becomes difficult to dissolve the resin.
In addition, this maleic anhydride-modified amorphous polypropylene resin can be used as an aqueous emulsion in place of the mixed solvent.
A water-based emulsion can be adjusted by adding an emulsifier, alcohol, and water.
The solid content concentration is preferably 20 to 40% by weight, more preferably 25 to 35% by weight.

On the other hand, the coating agent is characterized by using an inorganic-organic composite coating agent.
Generally, an inorganic-only coating agent has good hardness and weather resistance, but tends to cause shrinkage cracks. In addition, an organic-only coating agent has good flexibility and film-forming properties, but has drawbacks in hardness and weather resistance.
In recent years, various companies have proposed and commercialized inorganic-organic composite coating agents (hybrid coating agents) that take advantage of the characteristics of inorganic and organic materials and do not cause cracks even when thickly applied. For example, by forming an inorganic siloxane matrix with aqueous nanosilica and a silane coupling agent, and simultaneously forming a hybrid cross-linked structure with organic functional groups, the coating agent for forming a room temperature inorganic coating film having crack resistance, or its hydrolysis Examples thereof include a coating agent containing a non-organic polymer, or a coating agent that is modified with acrylic, urethane, amide, or melamine based on a silicon resin having a terminal -SiOH type.

By using the coating agent, the surface of the adherend can be cured at room temperature, and expensive ultraviolet irradiation and a heating device are not required.
The shape of the adherend molded article can be selected as appropriate depending on the application, but a sheet, a film, a plate shape and the like are preferable.
Furthermore, the coating agent can be coated by an ordinary application method, and various application methods such as brush coating, spraying, dipping, and roll can be selected.
The thickness of the coating film formed at this time is preferably about 20 to 50 μm as a dry coating film.

    As described above, by using a primer excellent in adhesiveness, blocking resistance and water resistance, and combining the above-mentioned inorganic-organic composite type coating agent, polyalkene such as polyethylene / polypropylene and cyclopentene heavy polymers which are hard-to-adhere coatings. Synthesis of polyolefin resins such as polymers and norbornene-based ring-opening polymers, polyester resins such as PET and PEN, (meth) acrylic resins, polystyrene resins, MS resins, AS resins, ABS resins, polycarbonate resins, and cellulose acetate butyrate resins A room temperature curing coating method for a resin or a metal surface such as aluminum, stainless steel, silver, or copper becomes possible.

  The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

The physical properties in the examples were evaluated as follows.
(1) Surface hardness: Pencil hardness was tested in accordance with JISK-5400.
(2B-4B)
(2) Adhesion: Inspection of coating agent adhesion on the test piece
Evaluation ◎ (good adhesion), △ (partially peeled), × (completely peeled)
(3) Water resistance: boiling for 30 minutes
Evaluation ◎ (no change), △ (milky), × (peeling)
(4) Steel wool resistance: 500 gf load 100 reciprocations
Evaluation ◎ (No scratches), △ (Some scratches), × (Scratches)

Production Example 1 (Production of maleic anhydride-modified amorphous polypropylene resin composition)
100 parts by weight of “Tough Selenium SCC25” (manufactured by Sumitomo Chemical Co., Ltd.) was sequentially added to a four-necked flask equipped with a nitrogen supply pipe and a cooler in an oil bath and equipped with a stirring blade and a thermometer. The temperature was raised to 170 ° C. over 3 hours. When the resin temperature in the system reached around 170 ° C., the system was rotated at 250 rpm to keep the system at a uniform temperature of 170 ° C. During this time, the dropping funnel was kept at 60 ° C., and 4 parts by weight of molten maleic anhydride (Nippon Yushi Co., Ltd.) and 1 part by weight of organic peroxide “Parhexa 25B” (Nippon Yushi Co., Ltd.) were added. Hold in each dropping funnel. When the inside of the system was uniform and stable, the maleic anhydride and the organic peroxide were added dropwise at a weight ratio of 4: 1. Ten minutes after the start of the dropping, the stirring speed was increased to 500 rpm to keep the stirring at a high speed, and a predetermined amount was dropped sequentially, and the reaction was performed at a system temperature of 150 to 170 ° C. for about 2 hours in a nitrogen atmosphere. After completion of the dropwise addition, the finishing reaction was performed at 150 to 160 ° C. for about 1 hour with high-speed stirring. The physical properties of the obtained maleic anhydride-modified amorphous polypropylene resin composition are as follows: maleation ratio is 1.3% (unreacted maleic anhydride is 0.1% or less), and melt viscosity is 27, at 185 ° C. The acid value was 100 mPa · s, the acid value was 12.6 mgKOH / g, and the weight average molecular weight was 81,610 (measured by GPC method).

Production Example 2 (Production of maleic anhydride-modified polypropylene resin composition)
Maleic anhydride-modified polypropylene resin composition according to the method described in Production Example 1 except that “VESTPLAST # 750” (polypropylene resin manufactured by Degussa AG: resin manufactured with Ziegler Natta catalyst) was used instead of “Tufselen SCC25” The product was synthesized. As for the physical properties of the resin composition, the maleation ratio was 1.3% (unreacted maleic anhydride was 0.1% or less), the melt viscosity was 23,000 mPa · s at 185 ° C., and the acid value was 29.9 mgKOH / g, The weight average molecular weight was 51,000 (measured by GPC method).

Example 1 (Manufacture of primer 1 and performance evaluation sample manufacture)
The maleic anhydride-modified amorphous polypropylene resin composition obtained in Production Example 1 was added to 64 parts by weight of a methylcyclohexane solvent, heated to 100 ° C. over 1.5 hours, and further completely dissolved over 1 hour. After cooling to 70 ° C., 16 parts by weight of ethyl acetate was additionally added and stirred for 30 minutes to obtain a primer composition having a solid content of 20% by mass and a viscosity of 84.3 mPa · s (25 ° C.).
The primer 1 was applied to a surface of a polypropylene test piece sample (length 70 mm × width 180 mm × thickness 5 mm) so that the surface was traced and dried.
After drying, an inorganic-organic nanocomposite “SSG Coat HB21A” manufactured by Nitto Boseki Co., Ltd. and an inorganic-organic hybrid coating agent “Compobrid CSS-H” manufactured by Atomics Co., Ltd. are applied by a flow coating method and 50% at room temperature. Humidity was allowed to stand for 4 days (room temperature curing) to obtain performance evaluation samples 1-A and 1-B.

Example 2 (Manufacture of water-based primer 2 and performance evaluation sample manufacture)
100 parts by weight of the maleic anhydride-modified amorphous polypropylene resin composition obtained in Production Example 1 and 31.5 parts by weight of methylcyclohexane are placed in a 1 L apparatus equipped with a helical ribbon blade and a cooler, and the resin is added over 4 hours. After melting and dissolving, the temperature was raised to 97 ° C. at 60 rpm. After 30 minutes, a mixed alcohol solution of 7.5 parts by weight of normal propyl alcohol (NPA) and 50.4 parts by weight of isopropyl alcohol (IPA) was added and stirred for 30 minutes to keep the temperature in the system at 85 ° C. Thereafter, 16.0 parts by weight of Esomine S / 25 (manufactured by Lion Akzo Co., Ltd.) and 4.0 parts by weight of deformer 399 (manufactured by Sannobuco Co., Ltd.) were added and stirred for 10 minutes. 28.4 parts by weight) was added, and the system temperature was raised to 100 ° C. Thereafter, the rotational speed of the stirring blade was gradually increased to 500 rpm, and a small amount of 470 parts by weight of ion-exchanged water was dropped over 8 hours. During this time, a very small amount of a mixture of methylcyclohexane, NPA / IPA alcohol, and water was distilled out of the system from the 1L cooling circulation line by 40 batch operations. After completion of the ion-exchange water injection, the system was stirred for about 30 minutes, the temperature in the system was lowered to 60 ° C., and filtered through 250 mesh to extract the water-based primer. The water-based primer composition has a solid content concentration of 29.4% by weight, pH 9.9, an average particle diameter of 1 to 1.5 μm, a viscosity of 29.0 mPa · s (25 ° C.), and the residual solvent is 0.17% by weight of NPA. IPA was 0.48% by weight and methylcyclohexane was 0% by weight.
Performance evaluation samples 2-A and 2-B were obtained using this primer 2 in the same manner as in Example 1.

Comparative Example 1 (Manufacture of primer 3 and manufacture of performance evaluation sample)
Instead of Production Example 1, the maleic anhydride-modified polypropylene resin composition obtained in Production Example 2 is mixed with 64 parts by weight of methylcyclohexane, heated to 100 ° C. over 1.5 hours, and further over 1 hour. After complete dissolution, the mixture was cooled to 70 ° C., 16 parts by weight of ethyl acetate was added, and the mixture was stirred for 30 minutes to obtain a primer composition having a solid content of 20% by mass and a viscosity of 92.0 mPa · s (25 ° C.). .
Performance evaluation samples 3-A and 3-B were obtained using this primer 3 in the same manner as in Example 1.

Comparative example 2 (manufacture of primer 4 and manufacture of performance evaluation sample)
Instead of the maleic anhydride-modified amorphous polypropylene-based resin composition obtained in Production Example 1, a commercially available polypropylene-based elastomer maleate having a part of crystallinity was used, and methyl cyclohexane and ethyl acetate were used instead. A primer composition having a solid content of 20% by weight and a viscosity of 83.5 mPa · s (25 ° C.) was obtained by the method described in Example 1 except that toluene and methyl ethyl ketone were used.
Performance evaluation samples 4-A and 4-B were obtained using this primer 4 in the same manner as in Example 1.

Comparative Example 3 (Production of primer-free performance evaluation sample)
Only a solvent without primer was applied to the surface of one side of a polypropylene test piece sample (length 70 mm × width 180 mm × thickness 5 mm) and dried.
In the same manner as in Example 1, performance evaluation samples 5-A and 5-B were obtained.

実施例−１および２はすべて要求性能を満足している。The performance evaluation was performed with A and B of the test piece samples 1 to 5 obtained in Examples 1-2 and Comparative Examples 1-3. The results are shown in Table-1.

Examples 1 and 2 all satisfy the required performance.

Claims (6)

Maleic acid modification in which an amorphous polypropylene resin synthesized with a metallocene catalyst having a weight average molecular weight of 70,000 to 200,000 and a molecular weight distribution (Mw / Mn) of 5 or less is modified with maleic anhydride. 15 to 25% by weight of maleic anhydride-modified polypropylene resin having a rate of 0.3 to 10.0% by weight and a weight average molecular weight of 40,000 to 150,000, a mixed solvent or aromatic of alicyclic hydrocarbon and ester A primer composition comprising 75 to 85% by weight of a hydrocarbon and ketone mixed solvent. Maleic acid modification in which an amorphous polypropylene resin synthesized with a metallocene catalyst having a weight average molecular weight of 70,000 to 200,000 and a molecular weight distribution (Mw / Mn) of 5 or less is modified with maleic anhydride. Primer composition of an aqueous emulsion comprising 15 to 25% by weight of maleic anhydride-modified polypropylene resin having a rate of 0.3 to 10.0% by weight, a weight average molecular weight of 40,000 to 150,000, and 75 to 85% by weight of water object. A ground treatment means for ground-treating the surface of the coated body with the primer composition according to claim 1 or 2, and an adherend coating for coating the ground-coated body with an inorganic-organic composite coating agent. A room temperature surface curing method comprising: means; and curing means for curing the surface of the adherend at room temperature. An inorganic-organic composite coating agent that forms an inorganic siloxane matrix with nanosilica and a silane coupling agent and at the same time forms a hybrid cross-linked structure with organic functional groups, or a hydrolytic type that contains a non-organic polymer. The room temperature surface curing method according to claim 3, wherein: 4. The room temperature surface according to claim 3, wherein the inorganic-organic composite coating agent is an acrylic-modified, urethane-modified, amide-modified, or melamine-modified material having a terminal -SiOH type silicon resin as a base material. Curing method. A surface-finished molded article, the surface of which is coated with the surface curing method according to claim 3, 4 or 5.