JPS62140679A - Production of resin molding - Google Patents

Abstract

PURPOSE:To provide a moist slippery feel to the surface of a resin molding by coating a paint consisting of a block type polyisocyanate prepolymer and foaming agent, etc., onto the surface of the resin molding and heating the coating after predrying, then subjecting the cured surface of the coated film to buffering, etc. CONSTITUTION:A paint compsn. essentially consisting of a chief material composed of the block type polyisocyanate prepolymer as well as the foaming agent, chain extender and fillers consisting of very small spherical bodies is coated on the surface to be coated of the resin molding. The paint compsn. coated on the surface to be coated of the resin molding is then predried to form the coated film. Foam is formed in the coated film by heating the coated film and at the same time is cured. The cured surface of the coated film is subjected to a surface treatment by means for brushing, blasting, buffing, etc. As a result, the moist slippery feel is provided to the surface and the resin molding having the ornamental surface which is rich in the high-grade feel is obtd.

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 coated with pile-flocked, suede-like, and fabric-like fabrics for the purpose of protecting and decorating the molded base material. Various decorative treatments have been applied, such as applying synthetic leather and coating with 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 texture of a solid 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 in addition, it is necessary to apply them to match the surface shape of the resin molded product, and the winding of the terminal part must be made in a separate process. 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 it lacks 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 developed a method for manufacturing resin molded products with a soft decorative skin that has a slimy feel. This is the heading that led to the present invention.

Structure of the Invention (Means for Solving the Problems) That is, the present invention provides (al) a base material made of a block polyisocyanate prepolymer, a foaming agent, a chain extender, and a microscopic (bl) a step of pre-drying the paint composition applied to the surface to be painted of the resin molded article to form a coating film; (C)
a step of forming air bubbles in the coating film and curing the coating film by heating the coating film; By devising a method for manufacturing resin molded products that is characterized by the following steps,
This is an attempt to solve the above problems.

(Function) The coating composition of the present invention is applied to the surface of a resin molded product or a resin molded product that has been subjected to the known decoration treatment, and the block type polyisocyanate prepolymer is heated after preliminary drying. The blocks come off and urethane bonds occur, and the foaming agent generates fine bubbles, forming a coating film with a soft texture.

In addition, the above coating film, together with the action of the filler consisting of microspheres in the coating composition, gives it a slimy appearance and feel, and is particularly effective when treated with flocked resin. When the above-mentioned coating film is formed on a molded article, a soft, suede-like decorative skin with a 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 main components of this coating composition are a main ingredient made of a block-type polyisocyanate prepolymer, a blowing agent, a chain extender, and a filler made of minute spherical bodies. What is a blocked polyisocyanate prepolymer? A blocking agent such as a terminal -N CO group such as an alcohol, a phenol, or an acetate is used. It is a polyisocyanate prepolymer that is inactive at room temperature and obtained by blocking with.

Examples of the polyisocyanate prepolymers include isocyanate prepolymers such as hexamethylene diisocyanate (HMDI), tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (MDI). , especially those with a molecular weight of 700 to 500
A non-yellowing HMDI prepolymer with a yellowing content of about 0 is the most suitable isocyanate for forming a soft coating film.

In addition, it is preferable to use the 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 suitable weight ratio is about 1:1.

Furthermore, polyols for forming the block type polyisocyanate prepolymer include polyethylene adipate (PEA) and polybutylene adipate (PB).
A) Polyester polyols such as polyhexamethylene adipate (PHA) and polycaprolactone (PCL) and polyethers such as polyoxypropylene diol (PPG), polytetramethylene glycol ether (PTMG), and polyoxyethylene diol (PEG) Although polyols can be used, polyester polyols are suitable for forming a soft coating film, and it is difficult to obtain coating film strength with polyether polyols.

In addition, the foaming agents include chemical foaming agents that thermally decompose rubber or synthetic resin at a predetermined temperature to generate N2, CO□, etc., and capsules made of synthetic resin microcapsules containing organic solvents such as low-molecular-weight alkanes. Although there are foaming agents, 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. If the amount of the blowing agent is less than 1 part by weight, the coating film will have a poor soft feel, and if it exceeds 50 parts by weight, the texture of the coating will become rough and the abrasion resistance will also decrease.

Furthermore, as a chain extender, a cationic surfactant with a molecular weight of 400 or more obtained by reacting a higher fatty acid such as stearic acid or behenic acid with an amino group-containing compound such as aminoethylethanolamine, diethyltriamine, or polyethylene polyamine is used. 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, and if it is less than 5 parts by weight, the soft feel of the coating film will be poor, and if it exceeds 40 parts by weight. The adhesive strength, abrasion resistance, weather resistance, etc. of the paint film will decrease.

Next, in order to reduce the tank size of the paint film, obtain a smooth and soft texture, reduce internal friction, and improve weather resistance, lubricants made of microspheres such as polystyrene, crosslinked polystyrene, and acrylic resin are used. It is effective to add

The particle size of the lubricant is preferably from several microns to several hundred microns, and the amount added is from 5 to 20 parts by weight, but not more than 5 parts by weight, based on 100 parts by weight of the block polyisocyanate prepolymer dispersion. There is no effect mentioned above,
Moreover, 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 become expensive.

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 various other molding methods.
As the resin base material, ABS resin, polystyrene resin (PS
), vinyl chloride resin (PVC), acrylonitrile-styrene copolymer resin (AS), ethylene-vinyl acetate copolymer resin (EVA), polyethylene (PE), polypropylene (
P P), thermoplastic resins such as acrylic resins, reaction-curing resins such as urethane resins, epoxy resins, polyester resins, polyamide resins, and thermosetting resins such as phenol resins, melamine resins, urea resins, formaldehyde resins, etc. Examples include synthetic 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, the method of the present invention will be explained in order of steps. First, the surface of the resin molded article to be coated is degreased, and then the coating composition is uniformly spray-coated.

There are various Vg 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.

Note that polyolefin-based 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 brimer or plasma treatment. Adhesion to the coating composition can be improved by adding a treatment step.

Next, the coating film is pre-dried by leaving the resin molded product at room temperature or drying it with warm air. In this pre-drying step, it is necessary to dry the coating film surface at least until it is dry to the touch, otherwise the gas in the blowing agent will scatter from the coating film surface when the coating film surface is heated in the next step. Numerous pores are formed on the surface of the coating film, resulting in loss of smoothness of the coating surface.

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.

Also, at this time, the foaming agent foams and creates fine air 1 in the coating film.
Since a package is formed, it is necessary to select a foaming agent that produces a package near 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 example]

Hereinafter, a first embodiment of a method for manufacturing an instrument panel (hereinafter abbreviated as an instrument panel), which is an interior component for a vehicle, will be described with reference to FIGS. 1 to 3.

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. Next, a soft intermediate layer made of vinyl chloride resin was coated on the surface side of the instrument panel base material, and a urethane adhesive was further applied to the surface of the soft intermediate layer, and then a length of 0.
An instrument panel was manufactured by flocking colored piles made of short polyamide fibers with a diameter of 4 mm and a fineness of 1 denier.

Table 1 (The parts in the table are @placed parts.) Next, after removing dust etc. attached to the pile surface by air blowing the instrument panel surface which has been subjected to the flocking process, apply the above coating composition. was evenly sprayed onto the instrument panel surface.

Thereafter, it was pre-dried by blowing hot air at about 50° C. for 30 minutes to form a coating film with an average thickness of about 100 μm 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 soft intermediate layer 3a made of vinyl chloride resin. . Furthermore, an adhesive layer 4 made of a urethane adhesive is coated on the surface of the soft intermediate layer 33, and the adhesive layer 4 is coated with a colored polyamide short fiber having a length Q of 4 am and a fineness of 1 denier. Pile 5 is flocked.

A coating film 6 made of the coating composition is almost uniformly applied to the surface of the pile 5.

Next, use a hot air dryer to dry only the surface of the coating film 60 by approximately 1
Heated at a temperature of 20°C to 130°C for 40 seconds. Due to this heating, the microcapsules of the packaging agent are torn and the coating film 6
Many fine bubbles are formed inside, and the coating film 6
hardening progresses.

After the coating film 6 was completely cured, its surface was brushed using a nylon brush to separate one to several flocked piles 5 at a time.

If this state is shown in Fig. 2.3, each or several of the piles 5 has a coating film 6 with many fine air bubbles 7 inside.
is formed.

Due to the synergistic effect of the soft feel of the pile 5 itself and the soft coating film 6, the surface of the instrument panel has a suede-like appearance and feel with a smooth and slimy feel, 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, the colored pile 5 made of short polyamide fibers with a length of 0.4cm-1 and a fineness of I denier was used.
In general, the pile suitable for the method of the present invention has a length of 0, 1-1.2 denier and a fineness of 0.1-7 denier, and piles made of polyester fibers in addition to the above-mentioned polyamide fibers may also be used. good.

As described above, according to the method of this embodiment, the simple process of applying a coating composition to the surface of a flocked resin molded product and then applying surface treatment produces a soft suede-like appearance. It is possible to obtain a decorated resin molded product that has a soft feel to the touch. What's more, the decorated 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 example]

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. 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 buckskin-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. After drying and forming a soft coating film 6 with an average thickness of 150 μm on the nonwoven fabric, 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 N3b, as well as the feel of the polished coating III 6, and has an improved appearance. The product not only has a soft feel, but also has a unique hackskin-like decorative skin that has a slimy texture that is not found in nonwoven fabrics.

[Third Example]

Figure 5.6 shows a third embodiment in which the method of the present invention is also applied to a center pillar garnish.The center pillar garnish with a U-shaped cross section used in this embodiment is made of ABS resin injection molded. The body is a base material 2, and a soft coating film 6 having a large number of fine bubbles 7 inside is coated on the surface thereof.

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. A soft coating film 6 with an average thickness of 100 μm was formed 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 long brush.

As described above, a large number of fine air 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, makes it look soft. Not only does it give a nice feel, but it also has a 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 examples, but can be applied by varying the blending ratio of each raw material in Table 1, or by performing surface treatment such as puffing or blasting instead of the brushing described above. 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 can be applied not only to the above-mentioned instrument panels and pillar garnishes, but also to a wide range of resin molded products, such as vehicle interior parts such as console box lids and armrests, and various residential interior decoration products. In this case, it is possible to obtain a decorative product that has an unprecedented shisotori and slimy feel and is full of luxury.

Furthermore, since the method of the present invention forms a decorated skin by spray coating, it is possible to obtain a decorated skin with a beautiful multicolor pattern on l1iJjJL by changing the color of the pigment and dye 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 a resin molded product having a slimy texture and a decorative skin full of luxury. Demonstrate the effect of what you can do. In addition, there is no need for the conventional process of attaching a decorative skin that is manufactured in a separate process to match the surface shape of the resin molded product, and the process of painting and surface treatment, which is similar to the process of painting and surface treatment, creates a soft and luxurious appearance. This is an excellent invention that also has the effect of reducing the manufacturing cost of the product because a decorated skin can be obtained.

[Brief explanation of drawings]

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, 4 is a sectional view of the center pillar garnish of the second embodiment, FIG. 5 is a sectional view of the center pillar garnish of the third embodiment, and FIG. 6 is a partially enlarged sectional view of FIG. 5. ■, 2... Base material, 3... Intermediate layer, 5... Pile, 6 ・
・Tsufunimembrane, 7 ・・Qi a. Patent applicant Toyoda Gosei Co., Ltd. Think Chemical Industry Co., Ltd. Agent Patent attorney Hironobu Onda Figure 1 Figure 4 b

Claims (1)

[Claims] 1. (a) On the surface to be painted of the resin molded product, a main ingredient consisting of a block type polyisocyanate prepolymer, a foaming agent,
(b) pre-drying the coating composition applied to the surface of the resin molded article to be coated; (c) forming bubbles in the coating film by heating the coating film and curing the coating film; (d) brushing the surface of the cured coating film;
A method for producing a resin molded product, comprising a step of surface treatment by means such as blasting or buffing.