JPS59202828A - Core vent for foaming mold - Google Patents

Abstract

PURPOSE:To obtain the core vent without loosening for a long period in use and drop therefrom by using specified composite resin material mixed with specified amount of glass fiber. CONSTITUTION:For resin materials, polyphenylene sulphide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polysulfon and polyether sulfone are cited. Particularly, polyphenylene sulphide has high thermal deformation temperature and moreover is excellent in strength, specially thermal resisting creeping property and high temperature water resisting property, whereby it is most suitable for a core vent. Glass fiber amount is selected in the range of 20-100pts.wt. for 100pts.wt. of said resin material. The glass fiber has 5-20mum diameter and is cut into 0.5-10mm. length, and the so-called chopped strand is used. For the structure of a core vent, the shape having a plurality of pieced holes in perpendicular direction to the base of the columnar core is used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a core vent used in a foam mold, and more particularly to a core vent made of plastic.

For example, the commonly used method for molding expanded polystyrene is to place raw expandable polystyrene beads in an aluminum mold, heat them with system steam from the outside, foam them, and then cool them with water before molding. This mold is used by drilling many holes in order to release the air, foaming gas, etc. inside the mold, and then punching them into the core vent.

This core vent is manufactured by cutting a metal such as brass into a structure as shown in FIG. However, since the shape is complex, cutting and other steps require a great deal of effort, leading to increased costs.

Furthermore, conventional core vents have major drawbacks.

When steam heating and water cooling are performed, 7ζ water droplets adhere to the core vent and are sucked into the mold when the mold is opened, wetting the foam. This necessitates a process of drying the molded product, which inevitably increases costs, and improvements have been desired.

As a method to improve this point, a core vent, which is a columnar body such as a cylinder, in which many small holes of 18 m or less are formed in a ridge has been proposed. Although this method is very effective, it is extremely difficult to penetrate small diameter holes in metal materials, and the only ones that can be commercially produced at present are those made of stainless steel, which is extremely expensive. Moreover, when used for a long period of time, it often swells and falls off due to heat cycles.

The inventors of the present invention have focused on this point and, as a result of intensive study, have decided to use a core vent molded from a composite resin material made by blending a specific type of glass fiber with a specific thermoplastic resin. They discovered that all of the above-mentioned drawbacks could be improved by this method, and arrived at the present invention.

The present invention will be explained in detail below.

As the resin material used in the present invention, a thermoplastic resin with high heat resistance is used. Specifically, polyphenylene sulfide and polycarbonate.

Bo Lib Chirentele 7 Tallate, Boririrun or Getalate.

Examples include polysulfone and polyethersulfone.

Among them, polyphenylene sulfide has a high heat deformation temperature and is excellent in strength, particularly in heat creep resistance and hot water resistance, making it the most suitable material for use as a cycoabent. Thermoplastic resins other than these, such as ABS, polystyrene, and polypropylene, have problems with heat resistance, creep resistance, hot water resistance, etc., and are difficult to use.

The amount of glass fiber is 20 parts by weight per 1-00 parts by weight of the above resin material.
It is selected within the range of parts by weight or more and parts by weight of 100N or less. 20
If it is less than 1 part by weight, it will not be possible to exhibit the vf characteristic of the present invention that does not reduce the removal rate, and furthermore, the strength will be low, so it will be easily damaged during driving, and the dimension MK will also be poor, making it impossible to obtain a satisfactory molded article. Moreover, if it exceeds 100 parts by weight, vo and dynamic properties will be poor, making it extremely difficult to form the fine through holes and slits of the present invention.

Aluminum, steel, etc. are used for foam molding molds, but depending on the metal of these molds, glass fiber filling may be
By adjusting the amount, the effects of the present invention can be effectively exhibited.

The glass fibers usually have a diameter of 5 to 20 μm and are cut into so-called long-length strands having a length of 5 to 10 μm. Although glass fiber is an essential component of the present invention, it is also possible to blend various inorganic fillers in addition to it as required. Inorganic fillers include silica, calcium carbonate, and talc.

Examples include whiskers.

Although various structures can be used for the core vent, in the present invention, one having a shape in which a plurality of through holes exist in a direction perpendicular to the bottom surface of a columnar core is adopted. The shape of the through hole is circular or square.

Polygonal shapes such as triangles and hexagons, other glazed shapes, slit shapes, etc. can be adopted. These through holes may also have a tapered shape. The plurality of through holes do not need to be of one type, nor do they need to be of the same size.

The size of the hole is 100mm” or less in area at the bottom1.
It is preferable that it is 01 m- or more. Also, its depth is 5
It is preferable that it is more than mm.

From the viewpoint of molding, it is advantageous to have larger holes, but if the depth exceeds 6 to 2 and is less than 5 i+m, a problem arises in which water droplets are sucked in when the mold is opened. Furthermore, if Q and DI are less than 2, molding is not only difficult, but also the pressure loss is large and the venting effect is insufficient. When the through hole is in the form of a slit, the slit is preferably 1.0 mm or less [11 urn or more in shape].

It is desirable that the aperture ratio at the bottom surface be 10% or more. If the amount is less than this, the venting effect will be insufficient and the number of pieces to be driven into the mold will increase, causing problems such as a decrease in the strength of the mold and an increase in cost. Further, although there is no particular upper limit to the aperture ratio, it is limited by mechanical strength and is up to about 80%.

The outer shape of the core vent is cylindrical, and may be tapered. The outer diameter is usually about 5 to 30 nm. Further, it is preferable that the length thereof is at least equal to or longer than the thickness of the mold, and that there are no one or four parts. Water accumulates in the fourth part, increasing the chance that water will be sucked into the mold when the mold is opened. Therefore, it is desirable that the depth of the hole is also the same as the length of the core.

The outer periphery may be knurled (9) to prevent it from loosening after driving, if necessary, and the tip may be tapered to facilitate driving.

By using Funao's composite resin material of the present invention as the core vent of the above structure, it can be used for long-term use.
In addition to not falling off, it is extremely difficult to manufacture such a fine structure with metal materials, but it can be mass-produced easily and inexpensively using common molding methods such as injection molding. It can be done.

Furthermore, since resin materials are more water repellent than metals, they are extremely advantageous in that they do not wet the foam, even with large through-holes or wide slits compared to metal core vents.

As explained above, the present invention can greatly improve the various drawbacks of conventional metal core vents, and has extremely great practical effects.

This will be specifically explained below using examples.

Example 1 In the structure illustrated in FIG. 6, the outer diameter of the core is 10B.

Length is 10ai+, medium, α5 in the direction perpendicular to the bottom
Polyphenylene sulfide 1o core vent with 40 circular through holes with an area of M20.

Injection molding was carried out using a machined resin in which 67 overlapping parts of glass fibers (chopped strands) having a length of 3+u+ and a diameter of 13μ were mixed based on the weight part.

Place this into the mold shown in Figure 7 at a pitch of 30Wm,
75C1x480xI We are molding polystyrene foam for packaging electrical products.

The molding conditions were as follows.

1. Filling with expandable polystyrene beads 2. Steam heating at 115°C for 40 seconds 5. Water cooling for 30 seconds 4. Vacuum cooling
The foam molded under these conditions showed no adhesion of water at all, and no drying process was required.

Further, even after 10,000 shots were continuously molded under the above conditions, no sagging of the core vent was observed, and no falling off occurred.

Comparative Example 1 A core vent having the structure described in Example 1 was prototyped using various metal materials, and as a result, it was possible to produce one batch of only stainless steel. This stainless steel core vent was placed in a mold and foam molded under the same conditions as in Example 1. As a result, a small amount of water was observed to adhere to the foam, and drying was necessary. Furthermore, as a result of continuous molding, some sagging occurred at the fourth shot, and three core vents fell off at the seventh shot.

Example 2 In the structure illustrated in FIG. 5, the outer diameter of the core is 10x+a.

A core vent with a length of 10IIIE, a width of Q, and 7 slits of 7 mrx pawned in a direction perpendicular to the bottom was injection molded using the composite resin material of Example 1, and a portion was molded. .

This core vent was placed in a mold and foam molded under the same conditions as in Example 1. As a result, no water was observed to adhere to the foam. 1. As a result of continuous molding, no sagging of the core vent was observed even after 10,000 shots were molded.

Comparative Example 2 As a result of trial manufacturing of a core vent having the structure of Example 2 using various metal materials, it was found that it was virtually impossible to inexpensively mass-produce a narrow and deep slit of 0.7 m.

Example 6 The same test as in Example 1 was conducted except that polyphenylene sulfide was changed to polyethersulfone and the glass fiber was changed to 43 parts by weight. As a result, no water was observed to adhere to the foam.

Further, even after 10,000 shots were continuously molded, no sagging of the core vent was observed.

Example 4 Except that the polyphenylene sulfide in Example 1 was changed to polybutylene phthalate and the glass fiber was changed to 43 parts by weight.
An identical test was conducted. As a result, no water was observed to adhere to the foam. Further, even after 10,000 shots were continuously molded, although some sagging was observed in the core vent, no falling off occurred.

Comparative Example 6 A core vent having the structure of Example 1 was molded from polyphenylene sulfide alone. This core ben) was mounted in a mold and the same test as in Example 1 was conducted.

As a result, the expansion causes cracks in the core vent,
I fell out after the first shot.

Comparative Example 4 - A core vent having the structure of Example 1 was molded from polybutylene phthalate alone. This core vent was attached to a mold and the same test as in Example 1 was conducted.

As a result, it deformed during steam heating and did not function as a vent.

Comparative Example 5 A core vent having the structure of Example 1 was injection molded using a composite ABS resin obtained by mixing 100 N parts of ABS resin with 43 parts of glass fibers having a diameter of 13 μm and a length of 311,111 cm.

This core vent was attached to a mold and the same test as in Example 1 was conducted. As a result, it deformed during steam heating and did not function as a vent.

FIG. 1 is a perspective view of a conventional core vent, and FIG. 2 is a longitudinal sectional view thereof.

3 and 5 are perspective views of the core vent according to the present invention;
and 6 are longitudinal sectional views thereof.

FIG. 7 is a schematic vertical cross-sectional view of a mold equipped with the core vent of the present invention.

1 Mold body 2 Core vent 6 Steam introduction line 4 Cooling water line 5 Drainage line Figure 2 Figure 4 Figure 6 Figure 5 Figure 7

Claims (1)

[Scope of Claims] (1) 20 to 1 part of glass fiber is added to 100 parts by weight of a thermoplastic resin selected from polyphenylene sulfide, polycarbonate, polybutylene phthalate, polyethylene terephthalate, polysulfone, and polyethersulfone.
A core vent for a foam mold molded from a composite resin material filled with 0.00 parts by weight. (2+ The core vent according to claim 1, wherein the thermoplastic resin is polyphenylene sulfide. (3) The core vent according to claim 1, wherein the glass fiber is chopped strand. (4) The core vent according to claim 1, wherein the glass fiber is chopped strand. The structure has a shape in which a plurality of columnar through holes exist in a direction perpendicular to the bottom surface of the columnar object, and the area of one hole on the bottom surface is 31112 or less α01++
rm” or more, the aperture ratio at the bottom is 10 inches or more, and the depth of the through hole is 5+x+i or more.
Core vents as described in any of the paragraphs. (5) The structure of the core vent has a shape in which a plurality of slit-like through holes exist in parallel in a direction perpendicular to the bottom surface of the columnar object, and the width of one slit in the bottom surface is 1 screen or less, 11 mm. Claims 1 to 3 above, wherein the aperture ratio at the bottom surface is 10% or more and the depth of the slit is 5 mm or more.
Core vents as described in any of the paragraphs.