JP2002097292A - Method of forming coating on crystalline thermoplastic resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a cured coating on the surface of a crystalline thermoplastic resin molding having excellent adhesion and appearance. SOLUTION: This method of forming a coating on a resin molding comprises the steps of roughening at least a part of surface of a crystalline thermoplastic resin molding, especially of polybutyleneterephthalate resin or polyphenylene sulfide resin molding, so that the surface roughness being 10 μm<=Rz<=40 μm (where Rz means an average roughness for 10 points), coating the roughened surface with two-pack curable resin composition, especially urethane resin composition or epoxy rein composition, and curing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a cured coating film having excellent adhesion strength on a surface of a molded article of a crystalline thermoplastic resin with a good appearance.

[0002]

2. Description of the Related Art Conventionally, the coating of a crystalline thermoplastic resin has
Pretreatment such as corona discharge treatment and flame treatment was required. However, these treatments have low adhesion strength of paint,
Also, it was necessary to make a huge capital investment. For this reason, there has been a demand for a method for obtaining a cured coating film having a high adhesion strength and a good appearance by using a conventionally used paint, adhesive, and printing ink, and performing a simple treatment.

[0003]

An object of the present invention is to provide a method for forming a cured coating film having excellent adhesion strength on a crystalline thermoplastic resin with a good appearance.

[0004]

Means for Solving the Problems When forming a coating film on the surface of a crystalline thermoplastic resin, the present inventors have tried various methods for realizing a coating with good appearance and excellent adhesion strength. The method was examined. As a result, they found that by roughening the surface of the crystalline thermoplastic resin molded article to a specific state, the surface area was increased and the anchor effect was improved, so that a uniform cured coating film with high adhesion strength was obtained. The present invention has been completed.

That is, a first aspect of the present invention is that at least a part of the surface of a crystalline thermoplastic resin molded product has a surface roughness of 10%.
After roughening so that μm ≦ Rz ≦ 40 μm (where Rz is a ten-point average roughness), the two-part curable resin composition is applied as a coating film on the roughened surface and cured. To provide a method for forming a coating film on a resin molded product. The second aspect of the present invention is
The first method for forming a coating film according to the present invention, wherein the roughening is performed by sand blasting, shot blasting, or liquid honing is provided. A third aspect of the present invention is that the crystalline thermoplastic resin is
The first or second coating film forming method of the present invention, which is a polybutylene terephthalate resin or a polyphenylene sulfide resin, is provided. A fourth aspect of the present invention provides the coating film forming method according to any one of the first to third aspects of the present invention, wherein the two-part curable resin composition is a urethane resin composition or an epoxy resin composition. A fifth aspect of the present invention provides the coating film forming method according to any one of the first to fourth aspects of the present invention, wherein the coating film is for painting, printing or bonding.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

As the crystalline thermoplastic resin used in the present invention, polybutylene terephthalate (PBT) resin,
Polyphenylene sulfide (PPS) resin and the like can be mentioned. In addition, an amorphous thermoplastic resin, for example, an ABS resin, an acrylic resin, a polycarbonate resin, a phenoxy resin, or the like may be used in combination with the crystalline thermoplastic resin. Various resin additives, fillers, and reinforcing materials can be added to the resin. In particular, examples of the reinforcing material include fibrous materials such as glass fiber, carbon fiber, aramid fiber, and whisker. In addition, a granular or powdery filler such as glass beads, talc, and mica may be used alone or in combination. In particular, in the case of baking after application, a material containing a reinforcing material is preferable.

The molded article used in the present invention may be one obtained by molding the above resin by any one of extrusion molding, injection molding, compression molding, vacuum molding, blow molding and foam molding.

As a method for roughening the surface of the molded article, a physical method such as sand blasting, shot blasting, and liquid honing can be used. The injection processing is a method of applying pressure to a grinding material (projection material) or accelerating by a centrifugal force, injecting from a nozzle, and colliding the grinding material with the surface of a molded product to roughen the surface. In shot blasting, a steel shot, a steel grid, a wire cut, abrasive grains, glass beads, an organic solid, or the like is used as a shot material. Projection methods include centrifugal projection, air acceleration, belt projection,
There are various methods such as water injection. Sand blasting is also called dry blasting, and is a method in which abrasive grains are jetted by air. The liquid honing is also referred to as wet-type blasting, and is a method of blasting abrasive grains with a liquid such as water. As the abrasive (projection material), a metallic abrasive, in particular, an alumina abrasive is preferable. However, glass beads having a spherical surface do not have a very good grinding effect. Number of abrasives is 100-22
0 is preferred. In the case of liquid honing, the liquid is preferably a solvent inert to the coating, especially water. Grinding conditions depend on the type, shape, concentration, etc. of the abrasive,
It can be appropriately adjusted so as to obtain a predetermined surface roughness.

By the above method, a desired portion of the surface of the resin molded product can be roughened so that the surface roughness is 10 μm ≦ Rz ≦ 40 μm (where Rz is a ten-point average roughness). This increases the surface area, improves the anchor effect of the coating film on the surface of the resin molded product, and reduces the dripping of the coating liquid. Surface roughness of resin molded product is 10μm
If less than 40 μm, the adhesion strength and coating efficiency of the coating film are low,
If it exceeds m, the surface will be affected by irregularities and the appearance will be poor. The part of the surface to be roughened may be the entire surface, a part thereof, one surface, or both surfaces.

On the roughened molded product surface, a coating film of the two-component curable resin composition is formed. Examples of the two-part curable resin composition include commonly used two-part urethane resins and two-part epoxy resins. Although a one-part curable resin composition may be used, a two-part curable resin composition has a more remarkable effect.

The two-pack type urethane resin comprises a polyisocyanate and an active hydrogen compound (polyol) as main raw materials, a catalyst, other chain extenders, a curing agent and the like. As the isocyanate, tolylene diisocyanate (T
DI), diphenylmethane diisocyanate (MD
I), polymeric MDI (MDI), tolidine diisocyanate (TODI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HMD)
I) aromatic or aromatic polyisocyanates such as isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), paraphenylene diisocyanate, hydrogenated XDI and hydrogenated MDI; isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI) and the like; and other lysine diisocyanates (LDI) and tetramethyl xylesodiisocyanate (TMXDI).

The polyol has a weight average molecular weight of 20.
Those from 0 to 100,000 are widely used and are classified into polyether polyols, polyester polyols and other polyols. Examples of polyether polyols include polypropylene glycol (PPG), polytetramethylene glycol (PTMG), and polymer polyols (polymerized acrylonitrile / styrene in PPG), PHD polyols, and modified products such as polyether polyamines. No. Examples of the polyester polyol include a condensation-based polyester polyol, a lactone-based polyester polyol, and a polycarbonate polyol. Condensation polyester polyols include condensation dehydration products of dibasic acids (mainly adipic acid) with glycols (ethylene glycol, 1,4 butanediol) and triols (trimethylolpropane). Other polyols include polybutadiene polyol (butadiene having a hydroxyl group at the end and a copolymer), acrylic polyol (a polyol having a hydroxyl group introduced into an acrylic copolymer), partially saponified EVA (ethylene-
(Vinyl acetate copolymer). Other examples include phenolic polyols, phosphorus-containing polyols and halogen-containing polyols as flame-retardant polyols, fluorine polyols, low-cost polyester polyols produced from PET resin waste and DMT residues, and the like. In addition, pigments, fillers, catalysts and other additives may be blended. Organometallic and amine catalysts can be used as the catalyst. Among the polyurethane resin paints, the one-pack type polyurethane resin paints include a lacquer type / moisture-curable type which does not require heating and a block isocyanate-curable type which requires heating, and can be used in the same manner as the two-part type. Has a more remarkable effect of surface roughening.

The two-pack type epoxy resin may be any of glycidyl ether type, glycidyl ester type, glycidylamine type and alicyclic type. The glycidyl ether type is a bifunctional type such as a general-purpose bisphenol A type, a low-viscosity biswaenol F type, a heat-resistant bisphenol S type or a biphenyl type, a flame-retardant brominated bisphenol A type, a bisphenol AF type, and a naphthalene. Fluorene type, non-yellowing hydrogenated bisphenol A type, and the like. As polyfunctional type, phenol novolak type,
Orthocresol novolak type, bisphenol A novolak type, trishydroxyphenylmethane type, tetraphenylolethane type, etc., are highly reactive with the curing agent, and the cured product is excellent in heat resistance, water resistance and the like. These can be used alone or in combination to impart properties.

Glycidyl ester type epoxy resins include carboxylic acid types such as phthalic acid derivatives and synthetic fatty acids;
The phthalic acid hydrogenated type or the like is used in combination with an acid anhydride curing agent for electrical insulation, weather resistance, and tracking resistance for outdoor equipment insulation. Further, a synthetic fatty acid type resin such as a flexible dimer acid or the like may be used.

The glycidylamine type resin includes tetraglycidyldiaminediphenylmethane (TGDDM),
Examples thereof include triglycidyl isocyanurate (TGIC), hydantoin type, 1,3-bis (N, N-diglycidylammonomethyl) cyclohexane (TETRAD-D) type, aminophenol type, aniline type, and toluidine type. These have characteristics of heat resistance and low viscosity (low melt viscosity), and are used for composite materials, powder coatings, and adhesives.

The curing agent used for the epoxy resin is diethylene triamine (DE) as a polyamine.
TA), triethylenetetramine (TETA), meta-xylylenediamine (MXDA), isophoronediamine (IPDA), 1,3-bisaminomethylcyclohexane (1,3BAC), diaminodiphenylmethane (MD
Z), m-phenylenediamine (MPDA), diaminodiphenylsulfone (DDS), dicyandiamide (D
1CY), organic acid dihydrazide; these modified products include polyamide (dimer acid modified), ketimine (ketone modified), epoxide modified (epoxy adduct), thiourea modified, Mannich modified, Michael addition modified; , Dodecenyl succinic anhydride (DDSA), polyazeleic anhydride (PAPA), hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), methylnadic anhydride (MNA), trimellitic anhydride (THA) , Pyromellitic anhydride (P
MDA), benzophenonetetracarboxylic acid (BTD)
A), tetrabromophthalic anhydride (TBPA), heptonic anhydride (HET); other novolak type phenol resins, phenolic polymers, polymercaptan, polysulfide, thioester, thioether, isocyanate prepolymer, blocked isocyanate; Acid-containing polyester resin; benzyldimethylamine (BDMA) in a catalyst-added organic acid type;
2,4,6-trisdimethylaminomethylphenol (EMDA), 2-methylimidazole (2MZ),
- ethyl 4- methylimidazole (EM), 2-heptadecyl imidazole (HD 12), BF ₃ monoethylamine, BF ₃ piperazine; as the ultraviolet-curable, Bunsuteddo salts such as aromatic sulfonium salts, aromatic diazonium salts; resole Phenol resin; methylol group-containing urea resin; methylol group-containing melamine resin.

According to the above-mentioned method, a coating film having extremely excellent adhesion can be formed on a crystalline thermoplastic resin molded product which is originally poor in coatability.
It can be formed economically so that the adhesion of the coating film is kept good for a long time. INDUSTRIAL APPLICABILITY The present invention can be used for a door handle of a vehicle, a roof rail, a reflector of a lamp, a personal computer, a mobile phone, an exterior of a housing part, and the like.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. (Resin used) Polybutylene terephthalate resin containing 30% by weight of glass fiber: DURANEX ^™ 3300 manufactured by Polyplastics Co., Ltd. Polyphenylene sulfide resin containing 40% by weight of glass fiber: FORTRON ^™ 1 manufactured by Polyplastics Co., Ltd.
140A6 (Surface roughness) Using a commercially available surface roughness meter, JIS B0
According to the method described in No. 601, the surface roughness of the roughened resin molded product was measured. The measurement result is the ten-point average roughness (R
z: unit μm). (Initial adhesion: according to JIS K5400 grid tape method) After leaving the coated product indoors for 24 hours, 11 cuts were made on the coated product at 1 mm intervals vertically and horizontally with a cutter knife, and the completed 100 1 mm pieces A cellophane tape (manufactured by Nichiban, 18 mm in width specified by JIS) is stuck on the square square with a length of about 50 mm, and the tape is completely adhered to the coating by rubbing with an eraser. One to two minutes after the tape is applied, one end of the tape is pinched with a finger to keep the tape perpendicular to the coated surface, and the tape is momentarily peeled off, and the peeling state of the painted portion is observed. The results were evaluated according to JIS 5400. (Appearance) According to JIS K5400 7.1 (5) Evaluation of Appearance of Coating Film. That is, ○ is normal, Δ is partly uneven due to the effect of surface roughening, and × is uneven as a whole.

Example 1 Using a polybutylene terephthalate resin containing 30% by weight of glass fiber, a flat resin molded product of 10 cm long × 10 cm wide × 3 mm thick was prepared using an injection molding machine. Next, using a liquid honing device, a commercially available brown alumina abrasive (particle size: # 100,
One side of the molded article was roughened under the conditions of an injection pressure of 5 atm and an injection time of 10 seconds using Japanese Industrial Standard R6111). At this stage, the surface roughness of the roughened surface of the molded article was measured. Table 1 shows the results. Next, a two-part curable urethane-based primer is applied to the roughened surface using air spray.
It was dried at 20 ° C. for 30 minutes. Thereafter, a two-component curable urethane-based paint was overcoated and dried at 80 ° C. for 30 minutes. After drying, the film was cooled to room temperature, and the thickness and adhesion of the coating film were evaluated. The thickness of the coating film is in accordance with JIS K5400 3.5,
For the measurement, a commercially available eddy current type film thickness meter was used. Table 1 shows the results.

Example 2 The same procedure as in Example 1 was carried out except that a polyphenylene sulfide resin containing 40% by weight of glass fiber was used. Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated, except that a brown alumina abrasive having a particle size of # 220 was used and the injection pressure was changed to 4 atm. Table 1 shows the results.

Example 4 A polybutylene terephthalate resin containing 30% by weight of glass fiber was used.
The same procedure as in Example 1 was carried out except that a roughening treatment was carried out at an injection pressure of 3 atm using 50 brown alumina abrasives. Table 1 shows the results.

Example 5 A polyphenylene sulfide resin containing 40% by weight of glass fiber was used, and the particle size was # 2.
The same procedure as in Example 1 was carried out except that a roughening treatment was performed at an injection pressure of 3 atm using 20 brown alumina-based abrasives. Table 1 shows the results.

[Comparative Examples 1 and 2] The same procedures as in Examples 1 and 2 were carried out except that the surface of the molded article was not subjected to a roughening treatment in advance. Table 2 shows the results.

[Comparative Examples 3 and 4] In Example 1 and Example 2, except that a commercially available brown alumina abrasive (particle size: # 46) was used, Example 1 (Comparative Example 3) and Example 2 ( Roughening treatment was performed in the same manner as in Comparative Example 4). Table 2 shows the results.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

According to the present invention, a coating film having high coating efficiency and excellent adhesion strength can be formed on a crystalline thermoplastic resin.

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Claims (5)

[Claims] 1. The method of claim 1, wherein at least a part of the surface of the crystalline thermoplastic resin molded product has a surface roughness of 10 μm ≦ Rz ≦ 40 μm.
(Where Rz is a ten-point average roughness), and then a two-part curable resin composition is applied as a coating film on the roughened surface and cured. Coating method. 2. The coating film forming method according to claim 1, wherein the roughening is performed by sand blast, shot blast, or liquid honing. 3. The coating film forming method according to claim 1, wherein the crystalline thermoplastic resin is a polybutylene terephthalate resin or a polyphenylene sulfide resin. 4. The method for forming a coating film according to claim 1, wherein the two-part curable resin composition is a urethane resin composition or an epoxy resin composition. 5. The method for forming a coating film according to claim 1, wherein the coating film is for coating, printing or bonding.