JPH0318515B2 - - Google Patents

Description

[Detailed description of the invention]

Object of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing decorative resin molded products used for vehicle interior parts, residential interior decoration parts, and the like. (Prior art) The surfaces of resin molded products such as vehicle interior parts, such as instrument panels, armrests, and pillar garnishes, are treated with flocking using panels and suede-like finishes for the purpose of protecting and decorating the molded base material. Various decorative treatments have been applied, such as fabric-like synthetic leather, and paint containing fillers such as beads. Furthermore, various decorative treatments are applied to the surfaces of various interior decoration products for homes made of resin molded products for the same purpose as described above. (Problems to be Solved by the Invention) However, the above various decoration processes have the following problems. That is, although the flocked hair has a soft feel, it lacks the solid feel of the material, and moreover, it tends to attract dust due to static electricity. In addition, in the case of applying suede-like or fabric-like synthetic leather, these synthetic leathers must be manufactured in a separate process, and since it is necessary to apply it to match the surface shape of the resin molded product, the winding of the terminal part must be The manufacturing process is complicated, and the cost of the product is high, as many other processes are required, such as embedding treatment, and if the surface shape of the resin molded product is complex, a lot of time is required for pasting. Furthermore, in the case of treatments that apply paint containing resin beads to the surface of a resin molded product to give it a visually soft feel (such as ravi painting), since the paint film itself is hard, The drawback is that it is not soft to the touch and does not provide a luxurious feel. In view of the above problems, the present inventors have conducted repeated research on various decorative materials and paints for resin molded products, and have found that:
The present invention was achieved by discovering a method for manufacturing a resin molded product having a soft decorative skin that has a firm and slimy feel. Structure of the Invention (Means for Solving the Problems) That is, the present invention provides (a) a base material consisting of a block type polyisocyanate pyrepolymer, a foaming agent, a chain extender, (b) Preliminarily drying the coating composition applied to the surface of the resin molded article to form a coating film. (c) heating the coating film to form bubbles in the coating film and curing the coating film; (d) brushing the surface of the cured coating film;
The above-mentioned problems have been solved by devising a method for producing a resin molded article, which comprises the steps of surface treatment by means such as blasting and buffing. (Function) By applying the coating composition of the present invention to the surface of a resin molded article or a resin molded article that has been subjected to the above-mentioned known decoration treatment, pre-drying and heat treatment, the block-type polyisocyanate prepolymer is coated. The block comes off and urethane bonding occurs, and
The foaming agent generates fine bubbles, forming a coating film with a soft texture. In addition, the above coating film, in combination with the action of the filler consisting of microspheres in the coating composition, gives a smooth and slimy feel both in appearance and touch. When the above-mentioned coating film is formed on a product, a decorated skin with a suede-like soft and luxurious feel can be obtained. (Example) First, the coating composition used in the method of the present invention will be explained. As mentioned above, the coating composition includes a main ingredient consisting of a block type polyisocyanate prepolymer,
The main ingredients are a blowing agent, a chain extender, and a filler consisting of minute spherical bodies. Here, the block type polyisocyanate prepolymer is a polyisocyanate prepolymer containing a terminal -NCO group containing alcohols, phenols, acetate, etc. It is a polyisocyanate prepolymer that is inactive at room temperature and obtained by blocking with a blocking agent such as ethyl acetate, ε-caprolactam, diethyl malonate, acetylacetone, hydrocyanic acid, or acidic sodium sulfite. Examples of the polyisocyanate prepolymers include isocyanate prepolymers such as hexamethylene diisocyanate (HMDI), tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). In particular, a non-yellowing HMDI prepolymer with a molecular weight of about 700 to 5000 is the most suitable isocyanate for forming a soft coating film. In addition, it is preferable to use the above block type polyisocyanate prepolymer by dispersing it in water using a nonionic, anionic or cationic surfactant. In this case, the block type polyisocyanate prepolymer and water A weight ratio of about 1:1 is appropriate. Further, polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate (PHA), polycaprolactone (PCL), and polyoxygen Polyether polyols such as propylene diol (PPG), polytetramethylene glycol ether (PTMG), and polyoxyethylene diol (PEC) can be used, but polyester polyols are suitable for forming soft coatings. However, in the case of polyether-based polyols, it is difficult to obtain coating film strength. In addition, the foaming agent is a chemical foaming agent that thermally decomposes rubber or synthetic resin at a predetermined temperature to generate N ₂ , CO ₂ , etc., and an organic solvent such as a low-molecular-weight alkane encapsulated in a synthetic resin microcapsule. There is a capsule foaming agent, but it is preferable to use a capsule foaming agent whose temperature can be easily controlled, and the amount thereof is 1 to 50 parts by weight per 100 parts by weight of the dispersion of the block type polyisocyanate prepolymer. be. If the amount of the blowing agent is less than 1 part by weight, the soft texture of the coating film will be poor, and if it exceeds 50 parts by weight, the texture of the coating film will become rough and the abrasion resistance will also decrease. Furthermore, as chain extenders, cationic surfactants with a molecular weight of 400 or more are obtained by reacting higher fatty acids such as stearic acid and behenic acid with amino group-containing compounds such as aminoethylethanolamine, diethyltriamine, and polyethylpolyamine. is appropriate. In addition, the blending amount is 5 to 40 parts by weight per 100 parts by weight of the dispersion of the block type polyisocyanate prepolymer,
If it is less than 5 parts by weight, the soft texture of the coating film will be poor, and 40
If the amount exceeds 1 part by weight, the adhesive strength, abrasion resistance, weather resistance, etc. of the coating film will decrease. Next, we reduce the tackiness of the paint film, giving it a firm, soft texture and reducing its internal friction.
In order to improve weather resistance, it is effective to add a lubricant made of microspheres such as polystyrene, crosslinked polystyrene, and acrylic resin. The particle size of the lubricant is preferably several microns to several hundred microns, and the amount added is 5 to 20 parts by weight, and 5 parts by weight, based on 100 parts by weight of the dispersion of the block type polyisocyanate prepolymer. If the amount is less than 20 parts by weight, the above-mentioned effect will not be obtained, and if it exceeds 20 parts by weight, the soft texture of the coating film will be poor and the cost of the coating composition will be high. Furthermore, the above coating composition contains organic or inorganic pigments or dyes. In addition, various additives that are normally added, such as anti-sag agents, anti-settling agents, and leveling agents, may be added. Next, a resin molded article to which the method of the present invention is applied will be explained. In other words, resin molded products are those obtained by injection molding, blow molding, extrusion molding, and other various molding methods, and the resin base materials include ABS resin, polystyrene resin (PS), vinyl chloride resin (PVC),
Acrylonitrile-styrene copolymer resin (AS),
Thermoplastic resins such as ethylene-vinyl acetate copolymer resin (EVA), polyethylene (PE), polypropylene (PP), acrylic resin, reaction-curable resins such as urethane resin, epoxy resin, polyester resin, polyamide resin, or phenolic resin, Examples include various synthetic resins such as thermosetting resins such as melamine resins, urea resins, and formaldehyde resins, and thermoplastic elastomers made of the above-mentioned thermoplastic resins and various rubber components may also be used. Further, the resin molded products used in the method of the present invention include those whose surfaces have been previously subjected to a well-known flocking process or those to which a soft decorative skin has been pasted. Next, to explain the method of the present invention in the order of its steps, first, after degreasing the surface to be painted of the resin molded product,
The coating composition is uniformly spray applied. There are various coating methods such as spray coating, dipping, and brush coating, but since it is necessary to form a coating film with a uniform thickness in the method of the present invention, it is preferable to use spray coating. Although the thickness varies depending on the type of resin molded product, it is usually preferably several tens of microns to several hundred microns. In addition, polyolefin thermoplastic resins such as PP and PE, thermoplastic elastomers containing these resins, reaction-curing resins, thermosetting resins, etc. have poor adhesion to paints, so do not use them before applying primer or plasma treatment. Adhesion to the coating composition can be improved by adding a treatment step. Next, leave the resin molded product at room temperature or
Alternatively, the coating film is pre-dried by drying with warm air. In this pre-drying step, it is necessary to dry the coating surface at least until it is dry to the touch.
Otherwise, when the coating surface is heated in the next process, the gas in the blowing agent will scatter from the coating surface, resulting in countless pores forming on the coating surface and loss of smoothness on the coating surface. Become. After preliminary drying, the surface of the coating film is heated at a predetermined temperature. The temperature at this time is the temperature necessary for the blocking agent of the block type polyisocyanate prepolymer to dissociate, and is usually 100°C or higher. Then, when the blocking agent dissociates, the polyisocyanate prepolymer and chain extender react to form urethane bonds and cure the coating film. Further, at this time, the foaming agent foams to form fine bubbles in the coating film, so it is necessary to select a foaming agent that foams at around the dissociation temperature of the blocking agent. Next, after the coating film is completely cured, its surface is treated by brushing, buffing, shot blasting, or the like. Since the texture of the coating surface changes slightly due to the difference in surface treatment means, a wide variety of decorated molded products can be obtained even when the same coating composition is used. FIRST EMBODIMENT Hereinafter, a first embodiment of a manufacturing method of an instrument panel (hereinafter abbreviated as an instrument panel), which is an interior part for a vehicle, will be explained according to FIGS. 1 to 3.
explain. A coating composition was prepared in advance by blending the raw materials shown in Table 1. On the other hand, a vehicle instrument panel base material was manufactured by injection molding polypropylene resin. Then,
A soft intermediate layer made of vinyl chloride resin is coated on the surface side of the instrument panel base material, and a urethane adhesive is applied to the surface of the soft intermediate layer, followed by coloring made of short polyamide fibers with a length of 0.4 mm and a fineness of 1 denier. An instrument panel was manufactured by flocking the pile.

【table】

[Table] Next, the surface of the instrument panel that had been subjected to the flocking process was air-blown to remove dust and the like adhering to the pile surface, and then the coating composition was uniformly sprayed onto the surface of the instrument panel. Thereafter, it was pre-dried by blowing warm air at about 50°C for 30 minutes to form a coating film with an average thickness of about 100μ on the pile. This state is shown in FIG. 1. The upper and outer surfaces of the instrument panel base material 1, which is an injection molded product of polypropylene resin and has a substantially U-shaped cross section, are covered with a cartilage intermediate layer 3a made of vinyl chloride resin. . moreover,
An adhesive layer 4 made of a urethane adhesive is coated on the surface of the soft intermediate layer 3a, and colored piles 5 made of short polyamide fibers having a length of 0.4 mm and a fineness of 1 denier are flocked to the adhesive layer 4. has been done. A coating film 6 made of the coating composition is almost uniformly applied to the surface of the pile 5. Next, only the surface of the coating film 6 was heated for 40 seconds at a temperature of about 120°C to 130°C using a hot air dryer. By this heating, the microcapsules of the foaming agent are ruptured, many fine bubbles are formed inside the coating film 6, and the coating film 6 is cured. After the coating film 6 was completely cured, the surface was brushed using a nylon brush to separate one to several flocked piles 5 at a time. If this state is shown in FIGS. 2 and 3, each or several piles 5 have many fine air bubbles 7 inside.
A coating film 6 having the following properties is formed. The surface of the instrument panel has a suede-like appearance and feel with a firm and slimy feel due to the synergistic effect of the soft feel of the pile 5 itself and the soft coating film 6, giving it an unprecedented sense of luxury. I was able to get a new instrument panel. Furthermore, since the surface of the instrument panel is coated with a coating film 6 of urethane resin, it also has the property of being less likely to generate static electricity. In this example, colored pile 5 made of short polyamide fibers with a length of 0.4 mm and a fineness of 1 denier was used, but in general, piles suitable for the method of the present invention have lengths of 0.4 mm and 1 denier.
A pile having a diameter of 0.1 to 1.2 mm and a fineness of 0.1 to 7 denier may be used in addition to the above-mentioned polyamide fibers. As described above, according to the method of this embodiment, the simple process of applying a coating composition to the surface of a resin molded product that has been subjected to flocking processing, and then subjecting it to surface treatment,
A decorated resin molded product having a soft suede-like appearance and feel can be obtained. What's more, the decorative skin has an unprecedented smooth and slimy feel, creating a unique sense of luxury not found in conventional products such as flocked products or synthetic leather. Second Embodiment Figure 4 shows a second embodiment in which the method of the present invention is applied to a center pillar garnish, which is also an interior part for a vehicle. The center pillar garnish is ABS
A nonwoven fabric is integrally attached as an intermediate layer 3b to the surface of a base material 2 made of resin by an in-mold molding method. A backskin-like soft coating film 6 is formed on the surface of the intermediate layer 3b. The method of this example is similar to the first example, in which a coating composition obtained by blending the raw materials shown in Table 1 is spray-coated onto the surface of the nonwoven fabric, and warm air at about 50°C is blown for 30 minutes to prepare the coating composition. Average film thickness on dry nonwoven fabric: approx.
After forming a soft coating film 6 of 150μ, the coating film 6 was completely cured, and the surface was further brushed using a nylon brush. Therefore, the center pillar garnish obtained by the method of this example has the soft feel and feel of the nonwoven fabric itself constituting the intermediate layer 3b, as well as the feel of the polished coating film 6. The product not only looks soft to the touch, but also has a unique buckskin-like decorative skin that has a firm and slimy feel that non-woven fabrics do not have. Third Embodiment Figures 5 and 6 show a third embodiment in which the method of the present invention is also embodied in a center pillar garnish. Nishi has a base material 2 made of an injection molded product of ABS resin, and a soft coating film 6 having a large number of fine bubbles 7 inside is coated on the surface of the base material 2. In this example method, a coating composition obtained by blending the raw materials shown in Table 1 is spray-coated onto the surface of the base material 2, and the base material is pre-dried by blowing warm air at about 50°C for 30 minutes. After forming a soft coating film 6 with an average thickness of about 100 μm on the surface of the coating film 2, the coating film 6 was completely cured, and the surface of the coating film 6 was further brushed using a nylon brush. As described above, a large number of fine bubbles 7 are formed inside the coating film 6 obtained by the method of this example, and this, together with the action of the filler made of microspheres, gives it a soft appearance. Not only does it give a soft feel, but it also has a firm, slimy feel to the touch, creating a calm and luxurious feel that cannot be obtained from conventional soft vinyl chloride resin skin materials. It should be noted that the method of the present invention is not limited to the above-mentioned embodiments, and may be modified by variously changing the blending ratio of each raw material in Table 1, or by performing surface treatment such as buffing or blasting instead of the above-mentioned brushing. By employing this method, it is possible to subtly change the texture of the coating film surface. In addition, the method of the present invention is applicable not only to the above-mentioned instrument panels and pillar garnishes, but also to console box slides,
It can be applied to a wide range of resin molded products, such as vehicle interior parts such as armrests and various residential interior decoration products, and in all cases, it has an unprecedented smooth and slimy feel and is decorated with a luxurious feel. You can get the product. Furthermore, since the method of the present invention forms a decorated skin by spray coating, it is possible to easily obtain a decorated skin with a beautiful multicolored pattern by changing the colors of pigments and dyes in the paint composition. There is also an advantage. Effects of the Invention As detailed above, by applying the above manufacturing method to various resin molded products, it is possible to obtain resin molded products that have a firm, slimy feel and a decorative skin that gives a luxurious feel. Demonstrate the effect of what you can do. In addition, there is no need to attach a decorative skin manufactured in a separate process to match the surface shape of the resin molded product, as in the past, and the simple process of painting and surface treatment creates a soft and luxurious finish. This is an excellent invention that also has the effect of reducing the manufacturing cost of the product because a decorative skin can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of the instrument panel of the first embodiment, FIG. 2 is a partially enlarged sectional view of FIG. 1,
Fig. 3 is an enlarged sectional view of the coating film applied to the pile, Fig. 4 is a sectional view of the center pillar garnish of the second embodiment, and Fig. 5 is a sectional view of the center pillar garnish of the third embodiment. Sectional view, and Figure 6 is the 5th
It is a partially enlarged sectional view of the figure. 1, 2... Base material, 3... Intermediate layer, 5... Pile, 6... Paint film, 7... Bubbles.

Claims (1)

[Scope of Claims] 1 (a) A resin molded article containing a main ingredient consisting of a block-type polyisocyanate prepolymer, a foaming agent, a chain extender, and a filler consisting of minute spherical bodies on the surface to be painted of a resin molded product. (b) Pre-drying the coating composition applied to the surface of the resin molded article to form a coating film; (c) Heating the coating film. (d) brushing the surface of the cured coating film;
A method for producing a resin molded product, comprising the steps of surface treatment by means such as blasting and buffing.