JPH0615030Y2 - Core vents for vapor permeation of foam molds - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a vapor-permeable core vent for a foam molding die, which is improved so as to prevent clogging caused by adhesion of foamed molten resin.

[Prior art]

Thermoplastic pre-expanded resin particles (hereinafter, simply referred to as expanded particles) are filled in the cavity of the mold, the expanded particles are heated and foamed by using steam as a heating medium, and the expanded particles are heat-sealed to each other to form an expanded molded article. The mold walls of the male and female molds of the mold device that can be manufactured are, for example, in Japanese Utility Model Laid-Open No. 56-16561.
As disclosed in Japanese Patent Publication No. 2 and Japanese Utility Model Publication No. 58-48112, a large number of vapor holes (generally called core vents) are mounted. The steam holes are formed by providing a large number of slits or small holes in the one-end closed surface portion of the cylindrical body made of aluminum.

[Problems to be solved by the device]

When the material of the foamed molded product is foamed particles formed of polystyrene or cross-linked polyethylene, the change in melt viscoelasticity due to the temperature change during molding is small, so there is little occurrence of clogging in the steam holes, but the above material is When the particles are crystalline expanded particles such as polypropylene and polyethylene which are not cross-linked (Japanese Patent Laid-Open Nos. 58-25334 and 62).
-212131), when the temperature of the expanded particles exceeds the melting point of the resin, the melt viscoelasticity is significantly reduced,
The molten resin invades the slits or small holes forming the vapor holes due to the foaming pressure and the restoring force against the compression filling. Due to this, when the molded product is released from the mold, the resin that has entered the slits and small holes will be cut off from the molded product, and the resin will remain on the steam hole side, causing clogging (usually 500 ~
Clogging begins to occur after 600 molding operations). When clogging occurs, it is necessary to stop the molding work and replace the core vents with ones that do not have clogging, but the number of core vents mounted on the mold is large, and the replacement work takes a considerable amount of time. It takes effort. Therefore,
There is a problem that productivity is lowered due to the suspension of the molding operation. Therefore, the object of the present invention is particularly effective when applied to small-hole type core vents, and the coefficient of friction against the molten resin is lowered to prevent clogging and improve the releasability. It is to provide a core vent for vapor permeation of a molding die.

[Means for Solving the Problems]

In order to achieve the above object, the core benz of the mold for foam molding, which is a feature of the present invention, is a core benz based on an aluminum cylindrical body having a large number of small holes formed in a closed surface at one end. Then, an intermediate layer of aluminum oxide integrally formed with these on the surface of the tubular body including the small holes, and a surface layer formed by adsorbing and binding a fluorohydrocarbon polymer to the intermediate layer are sequentially formed. It is provided.

[Action]

Since the surface layer of the tubular body including the small holes is formed of the fluorohydrocarbon polymer adsorbed and bonded to the intermediate layer, the adhesion of the molten resin can be prevented and the problem of clogging can be solved.

【Example】

Embodiments of the present invention will be described below with reference to the accompanying drawings. Reference numeral 1 denotes a tubular body made of aluminum which is a base material of the core benz. One end closed surface portion 2a thereof is provided with a large number of small holes 3 for permeation and the other end surface portion 2b side is opened. ing. Then, an intermediate layer 4 of aluminum oxide integrally formed with the surface of the tubular body 1 including the hole wall surface of the small holes 3 is further adsorbed and bonded to the intermediate layer 4 with a fluorohydrocarbon polymer. The formed surface layer 5 is sequentially provided to form a core benz. The surface layer 5 is formed as a film in which the fluorohydrocarbon polymer penetrates into the gaps and pores of the intermediate layer 4 as shown in FIG. 2. As disclosed in JP-B-52-39059, the surface of aluminum is corroded by a strong inorganic acid (etchin
g) and then forming small holes or recesses on the surface, applying a fluorocarbon resin on it and sintering, or aluminum material,
About 112 to 13 kept at a low temperature of about -3.9 to 4.4 ° C
In a sulfuric acid aqueous solution having a concentration of 5 g / g, the voltage was about 24 to 90 V and the current density was gradually increased from about 25 to 60 amps / Ft ² while stirring with air, and anodization was performed on the substrate surface. A porous adsorbent aluminum oxide layer composed of irregular coarse crystal particles is formed integrally with a substrate, and the aluminum oxide layer is impregnated with an aqueous dispersion of a fluorohydrocarbon polymer having a particle size of 2 μm or less. A method of forming a fluorohydrocarbon polymer film by drying is known. Next, an example of manufacturing an in-mold foam body using a mold equipped with core vents will be described, and then the clogging state of the steam holes according to the present invention and the comparative example will be compared. The method shown in Example 1 of JP-A No. 62-198444 (compression filling, in-mold heating particle fusion bonding method) using expanded particles of ethylene / propylene copolymer having a bulk density of 28 g / Was molded by. A mold having a width of 300 mm, a length of 300 mm, and a height of 50 mm was used to manufacture a molded product having an inner volume of 4.5. The mold of this molding machine is not provided with the core vent according to the present invention (product of the present invention), the slit type core vent having the same surface layer 5 as the present invention (Comparative Example I), and the surface layer 5. Ordinary aluminum small-hole type core vents (Comparative Example II) and ordinary aluminum slit-type Koabentsu (Comparative Example III) not equipped with the surface layer 5 are mounted respectively to mold the in-mold foam. The work was performed, and the number of shots at which each core benzine was clogged with the polypropylene resin and steam heating was insufficient was examined with the molding step as one shot. The results are shown in the table below. The diameter of the small hole is 0.5mm and the width of the slit is 0.5mm.
Is.

[Effect of device]

The present invention is as described above, and is formed by providing an intermediate layer of aluminum oxide on the surface of an aluminum tubular body which is a base material of core benz and adsorbing and binding a fluorohydrocarbon polymer to the intermediate layer. Since the surface layers are provided in sequence, adhesion of molten resin is prevented by this surface layer, and the mold releasability of the core benz from the molded product is also improved, as compared with the conventional core benz as can be confirmed in the table above. It is remarkably excellent in terms of preventing clogging, has excellent durability, and is extremely effective in achieving higher productivity.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a side sectional view and FIG. 2 is an enlarged sectional view of a portion A in FIG. In the figure, 1 is a cylindrical body, 2a is a closed end surface portion, 3 is a small hole, 4
Is an intermediate layer, and 5 is a surface layer.

Claims (1)

[Scope of utility model registration request] 1. A core benz based on a cylindrical body made of aluminum having a large number of small holes formed at one end closed surface portion, the core benz including the small holes being integrated with these on the surface of the cylindrical body. For the vapor permeation of a foam molding die, characterized in that an intermediate layer of aluminum oxide formed on the intermediate layer is further provided with a surface layer formed by adsorbing and binding a fluorohydrocarbon polymer to the intermediate layer. Core Benz.