JPH037491B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a decorative and protective molding in which a transparent polyurethane layer with a regular meniscus is formed on the upper surface of a band-shaped base made of synthetic resin. Specific examples of this molding include automobile side moldings, bumper moldings, rocker moldings, interior decoration strips, and the like. <Prior art> The above-mentioned type of decorative and protective molding (hereinafter referred to as "mall") is, for example, as shown in Fig. 1, which is a band-shaped synthetic resin strip with edge-shaped edges on both sides. It is manufactured by a method (so-called potting) of forming a transparent polyurethane layer 2 having a positive meniscus by pouring a liquid polyurethane material of an appropriate viscosity onto the upper surface 1a of the base body 1 and curing it (Japanese Patent Laid-Open No. 58-221741 (Refer to the publication number, etc.) In addition, in the illustration, 3 is double-sided adhesive tape,
4 is release paper. As the above-mentioned polyurethane material, a so-called two-component type material consisting of a polyol component and a polyisocyanate component is often used, which has excellent physical properties from the viewpoint of abrasion resistance and impact resistance. Usually, in this case, the upper surface 1a of the strip base body (usually made of PVC) has a
A colored coating film 5 is formed by applying and curing urethane paint. <Problems to be Solved by the Invention> However, when a polyurethane material is poured onto this colored coating film and heated and cured, bubbles tend to occur between the colored coating film 5 and the transparent polyurethane layer 2. This generation of bubbles can be solved by setting the heating temperature to 50° C. or lower and curing time to several hours, but this is not desirable from the viewpoint of productivity. <Means for Solving the Problems> In order to solve the above-mentioned problems, the inventors of the present invention made extensive efforts in development and came up with a method for manufacturing a decorative and protective molding having the following configuration. A urethane catalyst is applied to the top surface of the synthetic resin band-shaped base body, and after drying, a polyurethane material consisting of a polyol component and a polyisocyanate component is poured and cured to form a transparent polyurethane with a positive meniscus on the top surface of the band-shaped base body. It is characterized by forming a layer. Each configuration of the above means will be explained in detail below (see FIG. 1). Here, we will take as an example the case where a urethane coating film is formed on the top surface of a band-shaped base body, but if the material of the band-shaped base body is ABS or polyamide, a transparent polyurethane layer is formed directly on the top surface of the band-shaped base body without intervening a urethane coating film. Even if foam is formed, a urethane coating is not necessary when bubbles occur. (1) The base body 1 is made of polyvinyl chloride (PVC), acrylonitrile butadiene styrene terpolymer (ABS), nylon (polyamide), polycarbonate, acrylonitrile styrene copolymer (AS), ionomer, etc., which have excellent heat resistance and impact resistance. Molded by extrusion or injection using synthetic resin material. (2) The urethane paint that forms the urethane coating may be either a polyol-curing type (two-component type) or a moisture-curing type (one-component type), but when used for automotive moldings, weather-resistant, flexible From the viewpoint of properties and the like, a two-component type consisting of a polyether polyol and an aliphatic polyisocyanate is preferable, and a colored paint is usually used. (3) The above-mentioned urethane paint is usually diluted to an appropriate viscosity with an organic solvent exemplified below and applied onto a substrate by dip coating, spray coating, brush coating, knife coating, roll coating, or the like. Organic solvents: acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, xylene, methyl acetate, ethyl acetate, isopropyl acetate, trichloroethylene, 1,
1,1-trichloroethane, dimethylformamide. (4) Examples of the above-mentioned catalyst include the following amine-based or organotin-based catalysts, which usually promote the urethanization reaction. Amine type...methylamine, ethylamine,
Propylamine, isoproamine, butylamine, hydrazine, triethylenediamine,
Dimethylethanolamine, triethanolamine, and phenolic salts of 1,8-diazabicyclo(5,4,0)undecene-7 (DBU). Organotin-based...dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin diesterate, tributyltin acetate, tributyltin octoate, tributyltin laurate, dioctyltin diacetate, dioctyltin dilaurate,
Diethyltin dioleate, monomethyltin dioleate. (5) The above catalyst is propyl alcohol or the same type of solvent as it was used to dilute the above urethane paint.
It is diluted to 0.5-10 wt% and applied using the conventional application method described above. If the catalyst is in liquid form, it may be used as is. Furthermore, from the viewpoint of leveling properties, it is desirable to add a silicone foam stabilizer. (6) The transparent polyurethane layer 2 is formed by potting a polyurethane material consisting of a polyol component and a polyisocyanate component, which has been sufficiently degassed under reduced pressure, onto the upper surface 1a of the base body 1. At this time, a heavy metal compound-based or amine-based catalyst that is commonly used for curing polyurethane is added to the polyurethane material. Furthermore, from the viewpoint of long-term quality stabilization of polyurethane, antioxidants and ultraviolet absorbers are added,
It is also possible to add a surfactant from the viewpoint of improving leveling properties, shortening defoaming time, etc. Naturally, these agents are used that do not reduce the transparency of the cured polyurethane product. The polyol component may be polyether-based or polyester-based, but the former is preferred from the viewpoint of flexibility. The polyisocyanate component may be either aliphatic or aromatic, but the former is preferred from the viewpoint of weather resistance. Examples of the polyether polyols include polypropylene glycol, polypropylene triol, polyethylene glycol, etc., and mixtures thereof, as well as alkylene oxide polyadducts of ethylene diamine, alkylene oxide polyadducts of bisphere A, and the like. The above aliphatic isocyanates include not only the original aliphatic group but also alicyclic ones, such as hexamethylene diisocyanate (HMDI), xylene diisocyanate (XDI), hydrogenated xylene diisocyanate (hydrogenated XDI), and 4,4'-methylene bis dicyclohexyl diisocyanate (H12MDI),
Methylcyclohexyl diisocyanate (hydrogenated)
TDI), isophorone diisocyanate (IPDI)
Non-yellowing products such as
Usually, from the viewpoint of handling, these are used in the form of polyol adducts or polymers with low volatility, to which a triol or the like is added. (7) Heat curing is usually carried out using a heating means such as a dryer or heating furnace at a temperature of 60 to 100°C.
Do this for 10 to 30 minutes. If the temperature exceeds 100℃, the base material will
In the case of PVC, etc., it softens and deforms, which is undesirable.
A high-speed urethane curing reaction is not induced at temperatures below 60°C. <Function> The reason why bubbles are no longer generated at the interface between the transparent polyurethane layer and the cured polyurethane coating is not clear, but it is presumed to be as follows. The reason for the generation of bubbles is that when the polyurethane material is poured onto the top surface of the base (including the urethane colored coating), the moisture drawn into the interface between the top surface of the base and the urethane material reacts with the polyisocyanate in the urethane material. _CO2 is generated. In that case,
When a catalyst is present on the top surface of the base, the polyisocyanate component reacts with the polyol component before it reacts with moisture, and because almost no moisture reacts, CO ₂ , which causes bubbles, is not generated. <Effects of the Invention> The method for manufacturing a decorative and protective molding of the present invention includes applying a catalyst for polyurethane before pouring and curing a polyurethane material consisting of a polyol component and a polyisocyanate component onto the upper surface of a synthetic resin base. By applying the coating, no bubbles are generated at the interface between the transparent polyurethane layer and the upper surface of the strip-shaped base body, even if the transparent polyurethane layer is cured at high temperatures (60 to 100°C), as will be confirmed in the following examples. Therefore, when a decorative and protective molding having a polyurethane transparent layer with a normal meniscus is manufactured by potting, the curing time of the transparent polyurethane layer can be significantly shortened, and productivity can be greatly improved. <Examples> Hereinafter, the present invention will be described in more detail based on Examples. Here, "part" indicates the number of parts mixed.
means "parts by weight" unless otherwise specified. (1) Preparation of the painted strip-shaped base body The following PVC compound was extruded at a temperature of 130 to 140°C into a rectangular cross section with a thickness of 4.5 mm x width of 40 mm and cut into 10 cm pieces. A urethane paint was spray-coated to a dry film thickness of 20 to 30 μm, and then dried at 80° C. for 1 hour. PVC compound polymer 100 parts DOP 70 Epoxidized soybean oil 5 Barium stearate 1 Zinc stearate 1 Dibutyltin gylaurate 1 Urethane paint (manufactured by Fujikura Kasei Co., Ltd.) Soflex 300 (base agent) 9 parts Rethane PG-60 (curing agent) 1 TZ-004 (thinner) 9 (2) Application of catalyst Each catalyst shown in Table 1 was coated with isopropyl alcohol (Example
Dilute with 5wt% silicone foam stabilizer (except for No. 11) to the indicated concentration and apply by dip coating.
It was dried at 60°C for 5 minutes. If the next potting step is carried out with moisture remaining, bubbles may occur. (3) Potting After degassing the polyol component and isocyanate component of the polyurethane material below under reduced pressure (conditions: 50°C x 5 mmHg x 1 hour), they are mixed in the indicated amounts and degassed again under vacuum (conditions: 50°C). ℃×5
mmHg x 5 minutes) and preheated to 70°C in the shape of a PVC base body (rectangular cross section; width 37 mm).
× height 10 mm) at a concentration of 0.2 g/cm ² and the time required for the surface to become sticky (curing time) was measured at the indicated curing temperature. Each curing time is
Shown in the table. In addition, in Comparative Examples 1 and 2, the catalyst coating step among the above steps was omitted. Polyurethane material; Propylene oxide adduct of bisphenol A (OH value = 310) 10 times propylene oxide, ethylene oxide adduct of bisphenol A (OH value = 78) 10 Dibutyltin dilaurate 0.01 Prepolymer of hexamethylene diisocyanate (NCO20%) 17 (4) Presence or absence of foam generation Each of the molds of Examples and Comparative Examples obtained by each of the above methods was visually judged. The results are shown in Table 1, and the examples that included a catalyst coating step generated almost no bubbles, whereas the comparative examples that did not apply a catalyst did so at a relatively low temperature of less than 50°C. Bubbles were generated unless the polyurethane transparent layer was cured over a long period of time.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an example of a molding to which the method of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Band-shaped base body, 1a... Upper surface of the band-shaped base body, 2... Transparent polyurethane layer, 5... Colored coating film.

Claims (1)

[Scope of Claims] 1. When manufacturing a decorative and protective molding in which a transparent polyurethane layer with a positive meniscus is formed on the upper surface of a band-shaped base made of synthetic resin, a catalyst for urethane is applied to the upper surface of the band-shaped base. A method for producing a decorative and protective molding, comprising the steps of: after coating and drying, a polyurethane material consisting of a polyol component and an isocyanate component is poured and cured to form the transparent polyurethane layer.