JPS585254A - Laminated aluminum foil - 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 The present invention relates to improvements in laminated aluminum foil,
In particular, the present invention relates to a heat-sealable laminated aluminum foil suitable for heat-resistant packaging materials and hot water supply piping.

Recently, it has been used as a material for filling and packaging high-viscosity materials at room temperature (paints, oils, asphalt) at high temperatures, or as a retort food packaging material that can be heat-treated with high-temperature steam.
Alternatively, there is a demand for heat-resistant aluminum foil that can be heat-sealed as a piping material for hot water supply parts of solar plants.

Cross-linked polyolea intecenate aluminum foil has been considered as a heat-resistant aluminum foil. This crosslinked polyolefin resin aluminum foil is mainly produced by the following method.

Method A: After producing a polyolefin film by the Intre-Silon method, electron beam irradiation is performed to produce a crosslinked polyolefin film. Next, the cross-linked polyolefin film and aluminum foil are laminated together using an adhesive and heated and pressed with a roll.
Let them wear it.

Method B Polyolefin is extruded and laminated onto aluminum foil to produce a polyolea ink laminate aluminum foil, and the polyoleain surface is crosslinked by irradiating electron beams.

However, these methods had the following drawbacks.

■In both the inflated silon method and the extruded xenate method, non-uniformity in film thickness inevitably occurs during production, so even if the same dose of irradiation is performed, differences in crosslinking occur, and non-uniformity in properties is unavoidable.

(2) In the case of method B, the adhesive strength between the polyolefin and the aluminum foil is insufficient, so there is a drawback that the two easily peel off. Also in method A, the i*m of the adhesive, the coating thickness,
If the heat and pressure bonding conditions of the rolls are inappropriate, a similar problem will occur, and the optimum bonding conditions are often narrow and within limits for manufacturing purposes.

■It is economically disadvantageous because it involves many steps and tends to increase costs due to irradiation. In order to overcome these drawbacks, recently a silane cross-linking method has been used to extrude and laminate a mixture of silicone-grafted polyolein and silanol condensation catalyst onto aluminum foil and cross-link it to produce heat-resistant polyolefin laminated alsinium foil. is being carried out on a trial basis. If this silane crosslinking method is used, the above-mentioned drawbacks (1), (2), and (3) can be eliminated, but this method also has the following drawbacks.

■Since it contains a silanol condensation catalyst, it is easy to cause early scorch inside the extruder during extrusion lamination. Therefore, there is considerable control over extrusion conditions such as extrusion melt temperature and screw speed Heat sealability becomes poor. Therefore, it is extremely difficult to achieve heat sealing unless heat sealing is preferably performed online after extrusion lamination.Therefore, in reality, it is difficult to perform bag making by heat sealing after extrusion lamination. Therefore, its usage is quite limited.

(2) Polyolefin pellets prepared by mixing silicone-grafted polyoleain and silanol condensation catalyst cannot be extruded unless used within 24 hours after mixing because a crosslinking reaction proceeds on the surface of the pellets. Therefore, a considerable amount of mixed pellets F is lost.

In this way, even with the silane crosslinking method, the actual situation is that it has not been manufactured for purposes other than specific uses that do not require heat-sealing.

The inventor of the present invention investigated the conditions for laminating extrusion work, etc. in order to improve the above drawbacks (■, ■, They discovered that extremely stable extrusion work was possible with almost no occurrence of extrusion, and when they laminated it with aluminum foil, they found that silicone graph
It has been discovered that the adhesion between the chloride lyorefine film and the aluminum foil is good, that high-temperature filling is possible, and that heat sealing, which was previously considered impossible, is also possible.

The present invention was made based on such knowledge,
To provide a laminated aluminum foil which can be heat-sealed and has good heat resistance and water resistance, by layer-fusion bonding of aluminum foil and silicone-grafted polyolein and crosslinking without adding a silanol condensation catalyst. It is something.

The silicone-grafted polyolefin used in the present invention is a high-density, medium-density or low-density polyolefin, abbreviated as polyethylene or polypropylene, or dicumyl peroxide (I) OF. ), tertiary butyl pervivalate (TBPP'), tertiary butyl peroxide (TBPO), preferably 0.01 to 0.5 by weight, and vinyl trinidoxysilane (
V'I'1tO8) and vinyltrimethoxysilane (VT
A silicone coupling agent having a silyl group capable of hydrolysis such as MO8) is used at 0.00%. It is obtained by adding it to an IN5.0 weight ratio, feeding it to a device that can perform heating mixing such as a Henshil mixer or extruder, and heating it at about 200°C. be.

The laminated aluminum foil according to the present invention is mainly manufactured by the following method. That is, the silicone-grafted polyolefin pellets obtained as described above are fed to an extruder having a T-die, and! It is colored into a film by die extrusion in a conventional manner.

Therefore, in the present invention, as shown in FIG.
The extruded silicone-grafted polyolefin film 2 is pasted onto an aluminum foil 3 while in a softened state, and is pressed by a pressure roll 4 to form a laminated aluminum foil 5.

The thus obtained laminated aluminum foil undergoes a crosslinking reaction with moisture in the external atmosphere, thereby improving heat resistance. Furthermore, as shown by the actual kHz shown below, the adhesive strength between the aluminum foil and the silicone-grafted polyolefin film is extremely large compared to the case of normal heat fusion bonding, and increases with the passage of crosslinking treatment time. It is surmised that some of the hydrolyzable silyl groups of the glycated polyolefin film chemically react with and adhere to the aluminum foil interface through the equilibration reaction proposed by Plueddemann.

Below is the margin H The thickness after lamination is about 50-300μ.

Next, Examples and Comparative Examples 1 to 3 will be described. Example 8 High density polyethylene (MI-20, density -0,
The thickness of
60μ silicone graph on 00μ aluminum foil)
Polyethylene film, extrusion temperature 230℃
The silicone-grafted high-density polyethylene pellets F used in Comparative Example 1 + Experimental Feeding were extruded and laminated at The same structure was extrusion laminated at an extrusion temperature of 230°C.

Comparative example 2! High density polyethylene (MI-20% density-0
, 955) was extruded into the same structure as in Example at an extrusion temperature of 230°C.

Comparative example 3X polypropylene (MI-zO1 density -0,9
04) was extruded and laminated with the same structure as in Example at an extrusion temperature of 270°C, and was left in an atmosphere of 50% relative humidity at 50°C to crosslink, and the adhesive strength and immersion in water were evaluated. Measure the change in adhesion strength and prolonging temperature due to
In addition, heat-sealability was investigated, and a bag of 30 x 30 x 30 CIm was made with a structure of polyolefin on the inner surface and aluminum foil on the outer surface, and the seams were made by machine sewing, and high-temperature filling properties were investigated.

The adhesive strength was measured using an audiograph tester at a tensile speed of 5Q.
Figure 2 shows the results of determining the adhesive strength between the polyolein film and the aluminum foil under the conditions of ss/min.

The change in adhesive strength due to immersion in water was determined by immersing a laminated aluminum foil in water at 23° C., taking it out after a certain period of time, and measuring the adhesive strength under the above measurement conditions. The results are shown in FIG.

As shown in FIG. 4, the blocking temperature is determined by superimposing the foil film surfaces of two sheets of veneer ζ-aluminum foils 5 on a 10×10 C1l sheet, applying a load 6 of 4 J9r, and placing the foils at a constant temperature for 24 hours. Then, after 24 hours, the load was removed and the polyolefin film surface adhered to '2'.
The temperature at which the sheets of laminated aluminum foil would not separate was determined and the results are shown in Table 1. Heat sealability was determined using a normal heat sealing machine at a temperature of 250°C for 10 seconds.
A sheet of kamenate aluminum foil was heat-sealed by overlapping the polyolefin film side, and judgment was made based on whether heat-sealing was possible. The results are shown in Table-1.

High-temperature filling properties were determined by filling the above-mentioned bag with the five-wall paint at a high temperature of 230°C, and determining whether the bag could be used as a heat-resistant aluminate foil or not based on whether the polyolefin on the inside of the bag did not melt.

The results are shown in Table-1.

The following is a comparison of the extrusion stability during extrusion lamination work. In Examples and Comparative Examples 2.3, 3
Although gel formation and other troubles did not occur even when the work was carried out continuously for several days, gel formation occurred in Comparative Example 1 after 2 hours, making stable long-term extrusion lamination work difficult. In addition, after stopping the extruder's screw rotation for 15 minutes, the screws were rotated again and the laminating work was started. In the example, the gel generation stopped 5 minutes after restarting and the product returned to its original state. Even after restarting, no gel occurred. On the other hand, in Comparative Example 1, gel continued to occur and did not return to its original state, making it impossible to stop the screw. This is Comparative Example 1 when considering the actual production line.
This shows that manufacturing is extremely difficult.

As is clear from the above practical examples, the laminated aluminum foil of the present invention has excellent extrusion stability, can be heat-sealed, and has good heat resistance and water resistance, so it can be used as a heat-resistant packaging material or as a solar panel material. It is extremely effective as a piping material for hot water supply parts of plants.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the vehicle construction method, Fig. 2 is a graph showing the results of the adhesive strength test of 41 laminated aluminum foil,
FIG. 3 is a graph showing changes in adhesive strength when immersed in water, and FIG. 4 is an explanatory diagram showing the blocking test. 1 ----1 Extruder 2 -------Silicone graph F polyolefin film 3 ------- Aluminum foil 4-111 Pressure roll 5 ---- Laminated aluminum foil 6 -----1 Load (4I9r) Figure 1 Figure 2 Figure 0 12345 Keimura Nikkyo Figure 3 Figure 4

Claims (1)

[Claims] 1. A laminated aluminum foil obtained by laminating and fusing aluminum foil and a silicone-grafted polyolein film and crosslinking them without adding a silanol condensation catalyst. 2. The laminated aluminum foil according to claim 1, wherein the silicone-grafted polyolein is a high-density polyethylene as a paste polymer.