JPS62116145A - Synthetic-resin hollow body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

5.

[゛Industrial application field]

The present invention relates to an improvement in a product in which a large number of sealed hollow bodies are arranged on a sheet by molding a synthetic resin film.

[Conventional technology]

Generally called "bubble cushioning material", "air cap", "
``cell mat'', ``air bag'' or ``air mat''
Synthetic resin hollow bodies such as those mentioned above, which are given product names such as , are widely used as cushioning materials and heat insulating materials, and are sometimes used as toys or as packaging materials for cosmetic effects. Various manufacturing techniques for this type of synthetic resin hollow body have been proposed, among which the manufacturing methods such as those disclosed in Japanese Patent Publication No. 38-330, Japanese Patent Publication No. 40795-1972, and Japanese Patent Publication No. 44357-1972 are representative. It is. The principle is that a synthetic resin film is molded using vacuum forming or other means with many dents (called a "cap film"), and a flat film (called a "pack film") or a film with similar dents. The purpose of this method is to bond a film with another film provided with a film to form a large number of sealed chambers. FIGS. 1A and 1B show typical examples of synthetic resin hollow bodies produced in this manner. By the way, when using conventional technology, what is sealed in this sealed chamber is the air that was nearby. Moreover, since this air is in contact with the synthetic resin film that has been heated to the plasticizing temperature, the temperature is at or around 100° C., and when the hollow product is cooled to room temperature, the volume contracts. For example, if air at 100°C is cooled to 20°C, its volume will be (273+20> / (273+100) =
It becomes 0.79 (times). Regarding an actual product, the height of the sealed chamber of the product is approximately 415 mm compared to the depth of the recess of the mold used for molding the cap film. The volumetric contraction of the air in the closed chamber not only reduces the height of the closed chamber and prevents the full utilization of synthetic resin materials, but also gives the product an unfavorable appearance with wrinkles on the top surface of the closed chamber. become. Therefore, the actual product is
It is not the ideal type shown in Figure 2, but the type shown in Figure 2.
The top portion 2a has a wrinkled cross-sectional shape. As a solution to this problem, it was devised to manufacture synthetic resin hollow bodies in a high-pressure chamber (1983-
32232>, but it is difficult to implement and the manufacturing cost is high, so it has not been put into practical use. On the other hand, the present inventor has discovered that gases other than air, liquids, etc.
The authors have researched the purpose of enclosing a medium containing solids in the colander, adopted the inflation method of film forming, and completed a method that achieved this purpose by blowing the desired medium into an inflation tube, which has already been disclosed. (Unexamined Japanese Patent Publication No. 60-99631M>.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems, to have a fully sealed chamber and a height not less than the depth of the mold, and thus to have a high degree of buffering force and heat insulation. To provide a synthetic resin hollow body which has a high commercial value, has good properties, is free from wrinkles and has an excellent appearance. Quantitative measurement by team (means for solving the problem) To explain with reference to the drawings, the synthetic resin hollow body of the present invention has a large number of four parts, as shown in FIG. 1A and B. In a synthetic resin hollow body 1 formed by gluing together a synthetic resin film 2 and a flat film 3 to form a large number of sealed chambers, the transmittance to the synthetic resin film in the sealed chamber 4 is lower than the transmittance of air. It is characterized by gas being sealed in. Various thermoplastic resins can be used as the synthetic resin to form the film, but low density polyethylene (LDPE)
are typical, and LDPE and high density polyethylene (
Blends of HDPE> are also used. L-LDPE is also a useful material. The gas to be sealed in the sealed chamber must meet the condition that its permeability to the synthetic resin film used is lower than that of air.
You can use anything you like as long as it is harmless. Practical use is also advantageous in that N2 is easily available, inexpensive, and safe. If desired, the degree of expansion of the hollow body can be arbitrarily controlled by mixing and sealing a plurality of gases having different permeability. The method described in JP-A-60-99631 mentioned above can be used to manufacture a synthetic resin hollow body having a sealed chamber filled with a specific gas. Other methods may also be used, for example, by using existing equipment and placing the entire device under an N2 gas atmosphere.
Since this operation can be performed under normal pressure, it goes without saying that this is easier than using a high-pressure chamber. [Function] In the synthetic resin hollow body of the present invention, the closed chamber that was filled immediately after manufacture deforms due to volumetric contraction as the sealed gas cools, and as a result, the height decreases and wrinkles form on the surface. It is the same as a product, but if you leave it unattended, the sealed chamber expands and becomes full again, which lasts for a long time. To explain the mechanism, as shown in FIG. 3A, gas G is sealed in a sealed chamber that is contracted immediately after manufacture, and air, that is, 02+N2, is present around it. Gas G tries to go out of the room, and 02 and N2 try to go into the room, passing through the film that forms the sealed room. The air permeability is 02 and N for the synthetic resin film.
It can be seen as a weighted average of the transmittance of 2, so due to the difference in transmittance, the amount of gas G escaping to the outdoors is
The amount of gas entering the room is more dominant, and the amount of gas existing in the sealed room increases. The intrusion of gas from the outside appears to stop when the pressure inside the sealed chamber increases and the amount that enters and the amount that comes out are balanced. The situation in which the expansion of the sealed chamber is completed in this manner is as shown in FIG. 3B. The following values have been measured as transmittance for LDPE, which is a typical film material (unit: cm - c
m/cm2・sec-axHQ). o2: 2.8 N2: 0.97 When using the N2 recommended above as the filler gas, N2
Since 02 has a much higher transmittance, 02 actively enters the sealed chamber from the outside. Considering that 02 continues to enter until the gas composition in the sealed room becomes the same as the surrounding air, the N2 in the air is 78% by volume, and 02 is 2
Assuming that it accounts for 1%, (7B+21＞/7B=1.27 (times),
There is room for the volume of N2 contracted by the aforementioned cooling to be recovered to 0.79x1.27=1.00 (times). That is, when N2 is filled in, the volume of the sealed chamber almost completely recovers to the volume at the time of manufacture. The temperature of the gas to be sealed is 10
If it is lower than 0℃, the operating temperature of the synthetic resin hollow body is 2
It will be easily understood that the closed chamber will expand better if the temperature is higher than 0°C. If a synthetic resin hollow body is manufactured using a cap film mold that gives the cross-sectional shape shown in Figure 1B, and the amount of gas in the sealed chamber exceeds the design value, the top part will be shaped as shown in Figure 4. The product will be raised in a dome shape. Note that the lower the permeability of the sealed gas to the film, the more likely the sealed chamber will expand, so it can be said that it is generally preferable.
However, if too much gas enters from the outside,
If the film is thin, the sealed chamber may not be able to withstand the increased pressure and may break, so care must be taken. (Example 1) d=0.9229/ClR3, MFR=0.8 DP
E is used as the material, and the basis weight is 509/7Ff.
A gas-filled synthetic resin hollow body was manufactured by the method disclosed in No. 99631. The concave portion of the cap film molding die was cylindrical, with a diameter of 10 m and a depth of 4 m. The sealed gas is N2, and the temperature at the time of filling is about 100°C. Immediately after manufacturing the synthetic resin hollow body, when it has cooled to room temperature,
The sealed chamber was wrinkled as shown in FIG. 2, but expanded in about 2 hours after being left to stand, and became full as shown in FIG. 1B. When we took out the gas in the sealed room and analyzed it by GC, it was found that 02
existence was confirmed. The conventional product made using the same mold had a height of 3.2 m per piece, but the height of the product according to the present invention was 3.2 m.
It had a height of 9mm. When we measured the compressive strength (i.e., compressive elastic modulus, compressive strength at break), static buffer coefficient, and compressive creep properties of the product of the present invention, we found that the product outperformed conventional products in all cases, indicating that this product is excellent as a cushioning material. It was confirmed that the product had excellent performance. (Example 2) The same LDPE as in Example 1 was used, but the basis weight was 100.
A synthetic resin hollow body was manufactured under the same conditions except that the ratio was 9/m. The expansion of the sealed chamber was completed approximately 4 hours after production, resulting in a hollow body having the cross-sectional shape shown in FIG. 1B. [Example 3] The same LDPE as in Example 1 was used as the material, but N was sealed.
A synthetic resin hollow body was manufactured under the same conditions except that the temperature of the two gases was 70°C. The expansion of the sealed chamber was completed in about 2 hours during production, and it swelled up into a dome shape as shown in Figure 4. Although this hollow body had slight wrinkles on the ridge of the sealed chamber, it did not damage the product value, and each piece had a height of 4.1 inches. [Example 4] The same LDPE as in Example 1 was used as the material, and it was also made from JP-A-60
A synthetic resin hollow body filled with N2 gas was manufactured by the method disclosed in No. 99631. The temperature when N2 is sealed is 70°C. In this example, the concave part of the cap film mold is 10 m in diameter and 4 J in height.
It was made into a hemispherical shape of 11111. The expansion of the sealed chamber was completed in 2 hours during the manufacturing process, and it became a solid hemisphere as shown in FIG. No wrinkles occurred in this hemisphere. [Example 5] L-L of d=0.9229/ClR3, VFR-0,8
Made of DPE, basis weight 50g/Td, JP-A-60
A synthetic resin hollow body filled with N2 gas at 70° C. was manufactured by the method disclosed in No. 99631. The cap film molding die had the same cylindrical recess as in Examples 1 to 3. Approximately 4 hours after production, the sealed chamber expanded and assumed the solid shape shown in FIG. 1B.

Example 6 Example 2 was repeated under the same conditions except that sulfur hexafluoride SF6 was used as the filler gas. After 1.5 hours of manufacture, the solid shape shown in FIG. 1B was obtained. After that, it continued to expand, and the expansion of the sealed chamber stopped after about 6 hours of production, and it took on the dome shape shown in Figure 4. Since SF6 has a lower transmittance than N2 as well as 02, it is thought that not only 02 but also N2 entered the sealed chamber, and the internal and external pressures were balanced in the state shown in FIG.

[Example 7] Roughly one layer of LDP was added to the synthetic resin hollow body obtained in Example 3.
The E film 5 was volatilized and laminated to obtain a product 1A having the structure shown in FIG. In order to evaluate bending rigidity, we extended a cantilever set in the horizontal direction and examined the limit of deflection due to its own weight, and found that the conventional product already showed deflection at an extended length of 120 am, whereas the product of this example Even 300#1I11 did not bend. τ Example 8 LD with d=0.922g/CrIt3, MFR=0.8
Using a material with aluminum powder kneaded into PH, the basis weight is 50g/
Example 3 was repeated at rd. Three sheets of the obtained synthetic resin hollow bodies were laminated to form a product 1B having the structure shown in FIG. The conventional one made by laminating three synthetic resin hollow bodies had a total thickness of 9.6 m, but this example had a total thickness of 12.3 m.
There was m1m. In addition, the average thermal conductivity measured in accordance with the method specified in JIS A 1412 is 0.04 kcal/m・h
Calculating the thermal resistance using r.degree. C. results in the following numbers. (Unit: hr/'C/kcal) Conventional product:
0.24 Example: 0.31

[Example 9] LD with d=0.922g/CIIt3, MFR=0.8
A synthetic resin hollow body filled with N2 gas at 100° C. was manufactured using PE and yellow color master kneaded together at 150 g/f by the method disclosed in JP-A-60-99631. In this example, the concave portion of the cap film molding die is in the shape of a diamond with a -side length of 10 mm and a depth of 4 seconds. Approximately 2 hours after production, the sealed chamber expanded and took on the shape shown in FIGS. 8A and 8B. Generally, a prismatic sealed chamber loses its shape if the internal gas pressure is insufficient, resulting in an unfavorable appearance, but the product of this example had a correct geometric shape and was beautiful. 1 Skin 541 The synthetic resin hollow body of the present invention has a closed chamber filled with gas! 1. Has high ability as a shock material. In particular, when used by filling the empty spaces of a package, fewer sheets than conventional products are required because of the sufficient height. For example, if a product with a height of 4.1M according to the present invention is used, compared to a conventional product with a height of 3.2Nn manufactured using the same mold, the product will have a height of 2.
You can save 2% on the materials department. The three-layered product shown in FIG. 6 has high bending rigidity and is "strong" as shown in Example 7. This property is also useful depending on the application. When the synthetic resin hollow body of the present invention is used as a heat insulating material, it has a higher thermal resistance value than a conventional product manufactured using the same material, so it has higher performance. This fact is as shown in Example 8. Since the synthetic resin hollow body of the present invention has no wrinkles on the top surface of the closed chamber, it has a very beautiful appearance and has high commercial value. In particular, this effect is remarkable when a closed chamber having a shape other than a columnar shape as shown in FIG. 8A and Example 9 is created, since the shape is maintained correctly. The fact that a synthetic resin hollow body has a cosmetic effect not only increases its own commercial value, but also increases the value of products packaged using it. Regardless of whether the method of JP-A-60-99631 is used as a manufacturing technique or the conventional method, the synthetic resin hollow body of the present invention can be easily manufactured, and its cost is 2 times lower than that of conventional products.
An increase of about 3% is sufficient.

[Brief explanation of drawings]

FIGS. 1A and 1B show typical embodiments of the synthetic resin hollow body of the present invention, with A being a plan view and B being a sectional view. FIG. 2 is an enlarged sectional view of a conventional synthetic resin hollow body. 3A and 3B are explanatory diagrams of the mechanism by which the sealed chamber expands in the synthetic resin hollow body of the present invention, where A shows the state before expansion and B shows the state after expansion, respectively. FIG. 4 is an enlarged sectional view showing a state in which the sealed chamber of the synthetic resin hollow body of the present invention is expanded beyond the design value. FIG. 5, FIG. 6, and FIG. 7 are all sectional views corresponding to FIG. 1B, showing other embodiments of the synthetic resin hollow body of the present invention. 8A and 8B also show still another embodiment of the synthetic resin hollow body of the present invention, where A is a plan view corresponding to FIG. 1A, and B is a cross section corresponding to FIG. 1B. It is a diagram. 1... Synthetic resin hollow body 2... Cap film 3... Pack film 4... Sealed chamber Patent applicant Kawakami Sangyo Co., Ltd. Agent Patent attorney Souo Suga 11th! IA Figure 1 B Figure 2 Figure 3 A Figure 3 B Figure 4 Figure 5 Figure 8 B

Claims (2)

[Claims] (1) In a synthetic resin hollow body formed by gluing together a synthetic resin film with many recesses and a flat film to form a large number of sealed chambers, the permeability of air to the synthetic resin film in the sealed chamber is A synthetic resin hollow body characterized by being filled with a gas lower than the (2) The synthetic resin hollow body according to claim 1, wherein the synthetic resin film is a polyethylene film and the sealed gas is nitrogen.