JPH10202677A - Heating type foaming machine with mold of variable vertical interval - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the foaming time and eliminate the generation of unevenness in foaming by monitoring the sensor output at any time and issuing a movement instruction for restoring the sensor output to the desired value to a lifting and lowering movement device in the case the output is beyond the given value. SOLUTION: A pressure sensor 4 for sensing the foaming pressure of a foamed body by contacting is provided on either of an heating top mold 1 or a heating bottom mold 2, and either one of the heating top mold 1 or the heating bottom mold 2 is formed into a fixed mold, while the other is formed into a movable mold moving up and down by a lifting and lowering movement device 6 to provide a movable mold movement up and down freely. The sensor output of the pressure sensor 4 is monitored at any time by the monitoring of a CPU 7 and an instruction device, and when its output is beyond the given value, a movement instruction for restoring the sensor output to the desired value is issued to the lifting and lowering movement device 6. The foaming time is shortened and the generation of unevenness in foaming is eliminated by the arrangement to improve productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a plate-like foam such as a polyolefin foam.

[0002]

2. Description of the Related Art Various apparatuses have been proposed for producing plate-like foams such as polyolefin foams. For example, in Japanese Patent Publication No. 2-42649 according to the present applicant's application, in the two-stage polyolefin foaming method, the intermediate primary foam obtained in the first step is subjected to a second step in which An apparatus is described in which a non-closed mold having a cross-sectional shape and dimensions corresponding to the dimensions is placed in a non-closed mold and foamed by jacket-type steam heating. or,
In Japanese Patent Publication No. Hei 6-22923 also filed by the present applicant, a plurality of box-shaped molds each having a heater or a heat medium flow path provided on the outer surface and having a lower side opened are provided. A plurality of suspending members provided with locking portions at both ends thereof so that the molds to be connected vertically can be connected at a constant interval, lifting means fixed to the uppermost mold for raising and lowering, and the mold An apparatus for producing a foam comprising a fastener for locking in place is described.

[0003]

In the prior art described above, in any case, the upper and lower spaces of the mold in which the intermediate primary foam is placed are set to the thickness of the final product. Since the intermediate primary foam to be secondary foamed is before secondary foaming, its upper and lower thickness is naturally smaller than the vertical spacing of the mold, and is only placed on the upper surface of the lower mold. There will be a gap with the lower surface of the mold.
In other words, in the conventional manufacturing apparatus, it can be said that the upper surface of the intermediate primary foam is a foaming apparatus that indirectly heats the upper surface of the intermediate primary foam through air, and causes a problem in both the heat transfer speed and the heat transfer efficiency. . That is, if the speed and efficiency of heat transfer are poor, the following problems occur. 1) Low productivity because long time is required for heating and foaming. 2) The use of a heat source for heating, for example, steam is large, so that the cost is poor. 3) Prolonged heat foaming increases the generation of a non-foamed layer on the foam surface, and is inferior in material efficiency. In addition, in the conventional manufacturing apparatus, since the upper surface of the intermediate primary foam is indirectly heated, uneven foaming of the upper and lower surfaces may occur.

Accordingly, an object of the present invention is to solve the above-mentioned drawbacks of the conventional manufacturing apparatus, to shorten the foaming time, and to provide a manufacturing apparatus which does not cause uneven foaming.

[0005]

According to the present invention, a box-shaped upper heating mold having a downward opening and having a heating device on the outer surface, and a lower heating mold having a heating device on the outer surface are provided. In the foam mold comprising: a sensor for sensing the foaming pressure of the foam by contacting either the upper heating mold or the lower heating mold; and forming the upper heating mold and the lower heating mold. One of the molds is a fixed mold, and the other is a movable mold that can be moved up and down by a lifting and lowering device.The output of the sensor is monitored as needed, and when the output exceeds a predetermined value, the output of the sensor reaches a desired value. There is provided a heating type foaming machine having a mold with a variable vertical spacing, wherein a monitoring and commanding device for commanding a movement command related to return to the lifting / lowering device is provided. Further, according to the present invention, there is also provided a heating foaming machine in which an upper heating mold and a lower heating mold are arranged in multiple stages in the vertical direction.

[0006]

According to the present invention, a direct heating type heating and foaming machine capable of closely contacting the foam at a constant pressure with both the upper heating mold and the lower heating mold is provided, so that the productivity can be improved. In addition, economic efficiency can be improved. With respect to a multi-stage foaming machine, the effects in the above points are further increased.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of a foaming machine according to the present invention will be described with reference to FIG. The foaming machine basically includes an upper heating mold 1, a lower heating mold 2, and a lateral heating mold 3 provided with a heating means such as a steam jacket. There is no. The greatest feature of the foaming machine of the present invention is that the distance between the upper heating mold 1 and the lower heating mold 2 can be adjusted in a controlled relationship during the heating foaming process.

That is, in the example shown in FIG. 1, the upper heating mold 1 is integrally formed with the horizontal heating mold 3 and is always in a fixed position. On the other hand, the lower heating mold 2 is provided with an elevating / lowering device 6 such as a screw jack or a hydraulic cylinder disposed below the lower heating mold 2, so that the intermediate primary foam is placed in the mold and the foamed product is removed. Not only can the lower heating mold 2 be moved up and down at the time of unloading, but as described below, a controlled downward movement can be made during the progress of secondary foaming of the intermediate primary foam. That is, the contact pressure sensor 4 is provided in the upper heating mold 1, and the sensor unit is arranged so as to be flush with the lower surface of the upper heating mold 1. This contact type pressure sensor 4
Changes the pressure sensed by the sensor into an electrical signal,
Send to PU7. The CPU 7 repeatedly checks the electric signal at a set time interval based on the clock.

In the upper heating mold 1 and the lower heating mold 2 having the above-described structures, the lower heating mold 2 is first lowered by the lifting / lowering device 6, and the intermediate primary foam is placed on the upper surface thereof. After that, the lower heating mold 2 is raised again and stopped at the point where the intermediate primary foam comes into contact with the lower surface of the upper heating mold 1. In such a relationship between the mold and the intermediate primary foam,
Secondary foaming by heating based on the steam jacket is started. The electric signal increased from the contact pressure sensor 4 as the secondary foaming proceeds is sent to the CPU 7. CPU 7
It is sequentially determined whether or not the electric signal is within the reference value. If the electric signal exceeds the reference value (for example, 0.25 kgf / cm ² ), the corresponding command value is picked up from the table, and the elevating device 6 is moved. And move it down by that command value. The downward movement of the lifting / lowering device 6 lowers the lower heating mold 2 and returns the contact pressure between the foaming intermediate primary foam and the upper heating mold 1 to a predetermined value. Hereinafter, as the secondary foaming proceeds, the above operation is repeated, and a constant range of pressure is constantly maintained in the foam.

In the above-described foaming machine, it is understood that the same effect can be obtained even if the mold that can move up and down is the upper heating mold 1 and the lower heating mold 2 is fixed. Let's do it. The foaming machines as described above can be combined in multiple stages to obtain a large number of foams at the same time. FIG. 2 shows the basic concept of such a multi-stage foaming apparatus in which details are omitted, such as a steam jacket. That is, a number of upper heating dies 1 are arranged at equal intervals in the up-down direction, and are fixed to and supported by a plurality of fixed columns 10, 11 erected in the left-right direction and in the front-rear direction. On the other hand, horizontal beam members 12 are fixed to the lower portions of a large number of lower heating molds 3, respectively. , 14. The left and right common pistons 13 and 14 use the hydraulic cylinders 15 and 1 when arranging the intermediate primary foam and taking out the foamed product.
6, 17, 18 and the like, it is moved up and down, and when the intermediate primary foam is foamed, it is moved down to keep the contact pressure of the mold constant.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

Example 1 (closed cell) Low density polyethylene resin (trade name: Mitsubishi Polyethylene LD)
YF-30 MFR: 1.1 g / 10 min. density:
0.920 (manufactured by Mitsubishi Chemical Corporation) 100 parts by weight (hereinafter referred to as "parts") were mixed with 16 parts of azodicarbonamide, 0.4 part of zinc white and 0.5 part of dicumyl peroxide with a mixing roll. The composition obtained by 190x
Fill into a 190 × 40 tmm pressure sealed mold,
After applying an external pressure of kg / cm ² and heating at 150 ° C. for 35 minutes to partially decompose the foaming agent and the crosslinking agent, the pressure was removed to obtain an intermediate primary foam. The intermediate primary foam has a thickness,
It had expanded about 1.6 times both vertically and horizontally. The primary foam is immediately transferred to the variable thickness foaming machine (600 × 6) of the present invention.
(00x maximum thickness of 120 tmm) and sandwiched between two iron plates, and heated with steam at 160 ° C by a jacket method. As a contact type pressure sensor, a Dainisco resin pressure sensor, a product of Dainisco Co., Ltd., was used.
The initial thickness is 72 mm, the bottom plate of the foaming machine starts to drop in 5 minutes after the start of heating, reaches the final thickness in 17 minutes, finishes heating in 19 minutes, cools out, cross-linked polyethylene with uniform fine bubbles A foam was obtained. The foam obtained had an apparent density of 0.03 g / cm ³ . It was confirmed that the displacement of the distance (corresponding to the thickness of the foam) between the upper heating mold and the lower heating mold for maintaining a constant foaming pressure with respect to the heating time forms a curve as shown in FIG. Comparative Example 1 In Example 1, an intermediate primary foam was obtained by the same composition and method as in Example 1, and a conventional jacket-type foaming machine (6
00x600x120tmm) and indirectly 160
The mixture was heated with steam at 25 ° C. for 25 minutes to obtain the same foam as in Example 1. The difference in the foaming time in the second step was 6 minutes.

Example 2 Ethylene vinyl acetate copolymer (trade name: EVA41H,
Vinyl acetate content 16%, manufactured by Mitsubishi Chemical Corporation) 100
Parts, azodicarbonamide 19 parts, activated zinc white 0.02
Parts, 0.04 part of zinc stearate, 0.01 part of urea, and 0.6 part of dicumyl peroxide.
(190x190x40t)
mm) and heated under pressure for 40 minutes to shape the foamable crosslinkable sheet. Next, the obtained foamable crosslinkable sheet was sandwiched between two iron plates of a variable thickness foaming machine (described above) of the present invention similar to that of Example 1, and was heated at 160 ° C. by a jacket type.
With steam. The initial thickness was 40 mm, and the bottom plate started to descend 30 minutes after the start of heating, reached the final thickness in 73 minutes, and finished heating in 75 minutes. After cooling, a foam having thin film cells was obtained. The obtained foam is passed several times between two constant-velocity rolls set at a roll interval of 5 mm,
The cell membrane was broken and the cells were communicated to obtain an open cell. The obtained open cell had an open cell ratio of 100%, an apparent density of 0.03 g / cm ³ , and a thin skin layer. It was confirmed that the displacement of the distance (corresponding to the thickness of the foam) between the upper heating mold and the lower heating mold for maintaining a constant foaming pressure with respect to the heating time forms a curve as shown in FIG. Comparative Example 2 An expandable crosslinkable sheet was obtained by the same composition and in the same manner as in Example 2, and was placed in the same conventional foaming machine as in Comparative Example 1 to obtain 1 sheet.
Foaming was completed 105 minutes after heating at 60 ° C. The difference in foaming time was 30 minutes. In the obtained foam, cells were communicated in the same manner as in Example 2 to obtain an open cell. The obtained open cell had an open cell ratio of 100% and an apparent density of 0.0
It was 3 g / cm ³ and the skin layer was thick.

[Brief description of the drawings]

FIG. 1 is a heating type foaming machine having a single-stage mold according to the present invention.

FIG. 2 is a heating type foaming machine having a multi-stage mold according to the present invention.

FIG. 3 is a curve showing the heating time in the case of a closed cell and the distance between the adjusted upper and lower heating dies.

FIG. 4 is a curve showing the heating time in the case of an open-cell foam and the distance between the adjusted upper and lower heating dies.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper heating mold, 2 ... Lower heating mold, 3 ... Side heating mold, 4 ... Contact pressure sensor, 5 ... Heat exchanger, 6 ... Elevating device, 7 ... CPU, 10, 11 ... Fixed pillar, 12 ... horizontal beam material, 13, 14 ... common piston, 15, 16, 1
7, 18 ... Hydraulic cylinder.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00

Claims (2)

[Claims] 1. A foam mold comprising a box-shaped upper heating mold having a heating device provided on an outer surface thereof and having a box shape opening downward, and a lower heating mold having a heating device provided on an outer surface thereof. Either the upper heating mold or the lower heating mold is provided with a sensor for sensing the foaming pressure of the foam by contact, and one of the upper heating mold and the lower heating mold is a fixed mold, and the other is Is a movable mold that can be moved up and down by a lifting and lowering device, and the sensor output is monitored as needed, and when the output exceeds a predetermined value, a movement command having a relation such that the sensor output returns to a desired value is issued. A heating-type foaming machine having a mold with a variable vertical spacing, comprising a monitoring and commanding device for commanding a lifting / lowering device. 2. The combination of the upper heating device and the lower heating device is arranged in multiple stages in the vertical direction, and a movable mold that can move up and down is connected to a common elevating device. The heating type foaming machine according to claim 1.