JPH04239055A - Composition for release sheet - Google Patents

Abstract

PURPOSE:To provide the title compsn. giving a release sheet which increases the production speed and can be used repeatedly in a process for producing a polyurethane foam. CONSTITUTION:The title compsn. is obtained by compounding 100 pts.wt. thermoplastic polyurethane resin contg. 0.1-3.0 pts.wt. unsatd. higher fatty acid amide wax with 0.1-5.0 pts.wt. silicone resin powder having a particle diameter of 5-30mum. Excellent release and slip properties of a release sheet prepd. from the compsn. together with the recovery effect due to stretchability of a polyurethane foam facilitate the production of the foam, contributing to a reduction in the foaming cycle. As the sheet itself is stretchable, it can be used repeatedly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a mold release sheet used to facilitate the removal of a molded product from a mold when a foamed molded product such as polyurethane is cast.

0002

[Prior Art] Conventionally, when manufacturing foam molded products such as polyurethane, a release agent such as silicone or wax is applied to the surface of the mold in advance in order to make it easier to remove the cast foamed molded product from the mold. A coating method was used.

However, in this method, the mold release agent must be applied every molding cycle, which not only complicates the work process, but also causes the mold release agent to scatter around when applied by spraying, etc. The problem was that the working environment deteriorated. In addition, in order to improve this problem, conventionally, polyolefin films such as polyethylene and polypropylene, water-soluble resin films such as polyvinyl alcohol, Teflon sheets, etc. are placed in the mold in place of the above-mentioned mold release agent. A method of casting and foaming in a mold has been proposed.
1360, JP 60-178012, JP 61-125815, etc.) All of these release sheets have poor flexibility and elasticity, so the temperature and pressure at the time of foaming make it difficult for the mold to hold. The uneven shape cannot be directly reflected in the molded product, so a release sheet must be forcibly adsorbed onto the mold surface using a method such as vacuum suction before the foamable resin is cast. , a mold with a complicated structure is required, and although a sheet that has been plastically deformed into such a mold shape can be taken out from the mold smoothly, it is difficult to remove the release sheet from the molded product that has been taken out. Even if the sheet was removed little by little while being stretched, this was not always satisfactory, as there would be a slight gap between the shape of the plastically deformed sheet and the shape of the mold, creating a new problem of not being able to reuse it. .

0004

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to make the casting work of foamable resin extremely easy, and to provide a sheet that can be removed from the molded product. An object of the present invention is to provide a composition for a mold release sheet during foam molding, which is not only extremely effective in improving production speed, such as being extremely easy to release, but also economically advantageous in that the sheet can be used repeatedly. It is in.

[0005]

[Means for Solving the Problems] As a result of intensive study on a release sheet composition suitable for removing foamed molded products after casting, the present inventors have developed a thermoplastic polyurethane composition containing a specific amide wax. If the sheet is made of a resin composition in which a predetermined amount of silicone resin powder is further blended with the resin, the flexibility of the thermoplastic polyurethane resin will allow the uneven shape of the mold to be accurately reflected, and the molded material will be removed. When removing the mold release sheet from the product, the excellent mold release effect of the amide wax, combined with the sliding effect of the silicone resin powder and the restoring effect based on the inherent elasticity of thermoplastic polyurethane resin, makes it extremely easy. The present invention was conceived based on the discovery that not only can the release sheet be removed, but also that the removed release sheet can be used repeatedly.

That is, the present invention uses silicone-based resin having a particle size of 5 to 30 μm to 100 parts by weight of a thermoplastic polyurethane resin containing 0.1 to 3.0 parts by weight of higher fatty acid amide wax having unsaturated bonds. The present invention relates to a composition for a release sheet during foam molding, characterized in that 0.1 to 5.0 parts by weight of resin powder is blended.

[0007] Hereinafter, the composition for a release sheet used in foam molding of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of a release sheet for foam molding using the composition of the present invention, in which a thermoplastic polyurethane resin 1 containing an amide wax of higher fatty acids having unsaturated bonds and a silicone resin powder are used. 2 shows a release sheet 3 in which 2 is blended. Further, FIG. 2 shows an example of foam molding using a mold release sheet using the composition of the present invention as shown in FIG. A mold release sheet 3 is placed on the upper mold surface, the mold is clamped, and a valve 7 is opened between the mold release sheet 3 and the release paper 6 stuck to the upper mold surface to inject the foamable polyurethane resin material 8. (b) is a cross-sectional view showing a state in which the foamable polyurethane resin material 8 expands and fills between the upper and lower molds, and (c) shows the state in which the foam molded body 9 is taken out from the mold. A cross-sectional view, and (d) a cross-sectional view showing how the release sheet 3 is removed from the foamed molded body 9.

In the present invention, a thermoplastic polyurethane resin is a thermoplastic rubber-like elastic polymer containing a urethane group in its molecular structure, which is made from bifunctional polyol, diisocyanate, and glycol as main raw materials. , Specifically, polyester-based, which is differentiated depending on the type of raw material such as the polyol used,
It is made of at least one type of polyurethane resin such as polyether type or polycarbonate type.

[0009] The thermoplastic polyurethane resin may have any hardness as long as it can follow the uneven shape of the mold by the pressure during foam molding. From the viewpoint of conformability and restoring force, it is preferable to use a material having a JIS hardness of 50 to 90 Hs.

[0010] The mold release sheet made of the composition of the present invention uses a thermoplastic polyurethane resin which has the above-mentioned excellent flexibility, elasticity, mechanical strength, abrasion resistance, etc. as the resin's original properties, so it can be cast. The release sheet follows the uneven shape of the mold extremely well due to the expansion pressure of the foamed resin at the time of production, and in addition to being able to accurately reflect the shape of the mold in the molded product, it also has excellent resilience and durability. Due to its excellent properties, it can be used repeatedly.

The thermoplastic polyurethane resin may contain other materials such as polyolefins, polystyrenes, etc. within a range that does not significantly impair its flexibility, elasticity, restoring force, etc.
Resins or elastomers such as polyvinyl chloride, polyester, and polyamide may be added, and antistatic agents, antioxidants, ultraviolet absorbers, lubricants, fillers,
Additives such as colorants may be added as appropriate.

The thermoplastic polyurethane resin used in the composition for a release sheet of the present invention contains an amide wax of higher fatty acid having an unsaturated bond. Here, the amide waxes of higher fatty acids having unsaturated bonds are ethylene bisoleic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ricinoleic acid amide, hexamethylene bis oleic acid amide, N,N'-dioic acid amide, etc. It consists of at least one type of wax such as railadipic acid amide, and the amount thereof is preferably 0.1 to 3.0 parts by weight, preferably 1.0 to 2.0 parts by weight. The amide type wax easily migrates to the sheet surface due to its compatibility with the thermoplastic polyurethane resin, and thereby exhibits an excellent mold release effect.

Therefore, if the content of the amide wax used in the present invention is less than 0.1 part by weight, the amount transferred to the sheet surface is small and a sufficient mold release effect cannot be obtained; If the amount is more than part by weight, too much will migrate to the sheet surface, making the sheet sticky and having poor slipperiness, which will not only impair workability, but also cause contamination of the surface of the foam molded product and penetration into the screw of the extruder during sheet production. Problems such as poor performance and extrusion fluctuations occur.

[0014] Furthermore, the silicone resin powder used in the present invention is originally a thermoplastic polyurethane resin that has strong adhesiveness and poor slipperiness, and the above-mentioned amide is formed by forming fine irregularities on the surface of the resin sheet. It has the effect of improving slipperiness, which cannot be achieved with waxes alone, and further improving sheet handling, releasability, and workability.
．． 0 parts by weight, preferably 0.5 to 3.0 parts by weight.

[0015] Here, the silicone resin powder is a spherical or amorphous powder having a three-dimensional network structure cross-linked with siloxane bonds, and when the particle size is less than 5μ, the unevenness of the sheet surface is small. Workability is poor due to poor slipperiness improvement effect, and on the other hand, if it exceeds 30μ, there arises the problem of poor appearance and the tendency to form holes during sheet film formation, resulting in a lack of film formation stability. Similarly, if the amount added is less than 0.1 parts by weight, no improvement in slip properties will be observed, and if it is more than 5.0 parts by weight, not only will the appearance be poor, but the stability of film formation will deteriorate.

[0016] The most common method for producing a release sheet from the composition of the present invention is an extrusion-based inflation method or a T-die method, but other methods such as a calender method or a casting method may be used to form a release sheet. It can also be molded,
In this case, the thickness of the sheet is usually about 20 to 100 μm, which is good in terms of handling and workability.

[0017]

[Examples] The composition for a release sheet used in foam molding of the present invention will be explained in detail below with reference to Examples.

Examples 1 to 3, Comparative Examples 2 to 7 Unsaturated higher fatty acids were added to a thermoplastic polyurethane resin (ether-based thermoplastic polyurethane resin "Takelac T880" JIS hardness 80Hs, manufactured by Takeda Birdish Polyurethane Industry Co., Ltd.) Ethylene bisoleic acid amide, which is an amide of
Toss Pearl") in various addition amounts was mixed with caliber 5.
A sheet with a thickness of 30 μm was produced by inflation molding using a 0 mm extruder. These release sheets were placed inside the upper and lower molds shaped as shown in Figure 2, and foamed polyurethane foam ((
Urethane foam "Insal Pack 25#" sold by ABC Shokai Co., Ltd.) was injected and foamed. Table 1 shows the releasability, slipperiness, and appearance of each sheet.

Example 4 A test was conducted in the same manner as in the above example except that oleic acid amide, which is an amide of unsaturated higher fatty acids, was used as the amide wax. The results are shown in Table 1.

Comparative Example 1 A test was conducted in the same manner as in the above example except that ethylene bisstearamide, which is an amide of saturated higher fatty acids, was used as the amide wax. The results are shown in Table 1.

[0021]

[Table 1]

Each performance evaluation in the table was performed by the following method. (1) Release property The 180° peel strength of the foam molded product and the release sheet is 10 g/
Those less than 20 mm were rated (○), and those 10 g/20 mm or more were rated (x). (2) Sliding property Release sheets are fixed on a table whose slope can be freely changed and on the bottom of a sled of a predetermined weight, and when the angle of the table is increased, the angle at which the sled starts to slide is less than 35 degrees. (○), and those with an angle of 35° or more were marked (x). (3) Judging by visual inspection, good items are marked with (○) and poor items are marked with (○).
x). (4) Comprehensive evaluation Based on the evaluation results of mold release properties, slipperiness, and appearance, those suitable as mold release sheets were marked (○), and those unsuitable were marked (x).

[0023]

Effects of the Invention As described above, the composition for a mold release sheet used in foam molding of the present invention has excellent mold release effects due to the amide wax having unsaturated bonds, and an improved slipperiness effect due to the addition of silicone resin powder. Combined with the restoring effect based on the inherent elasticity of thermoplastic polyurethane resin, workability is extremely good, and the flexibility of thermoplastic polyurethane resin allows the uneven shape of the mold to be easily molded using the foaming pressure during molding. This can be reflected in

In addition, the sheet obtained from the composition of the present invention has a characteristic that it can be reused even after being used once because it is highly elastic, and as mentioned above, the mold release operation is easy, so that the foaming cycle can be shortened. The economic benefits are also enormous, such as the realization of a new technology and a significant contribution to improving productivity.

[0025]

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a release sheet obtained from the composition of the present invention.

FIGS. 2A to 2D are cross-sectional views showing an example of foam molding using the release sheet of the present invention.

[Explanation of symbols]

1 Thermoplastic polyurethane resin containing amide wax having unsaturated bonds 2 Silicone resin powder 3 Release sheet 4 Upper mold 5 Lower mold 6 Release paper 7 Valve 8 Foaming polyurethane resin material 9 Foam molded product

Claims (2)

[Claims] Claim 1: Silicone resin powder with a particle size of 5 to 30 μm is added to 100 parts by weight of a thermoplastic polyurethane resin containing 0.1 to 3.0 parts by weight of higher fatty acid amide wax having unsaturated bonds. A composition for a release sheet during foam molding, characterized in that the composition is blended in an amount of 0.1 to 5.0 parts by weight. 2. A composition for a release sheet, wherein the thermoplastic polyurethane resin according to claim 1 has a JIS hardness of 50 to 90 Hs.