JPS63165121A - Method for embossing polyolefine laminate - Google Patents

Abstract

PURPOSE:To realize a finished state having uniform gloss by a method wherein a water film is interposed between the surface of a roll and the surface of a workpiece by getting the surface of a embossing roll wet with water. CONSTITUTION:An embossing roll 1 the wetting tension on the surface of which is 45 dyn/cm or more is used. A sprinkling position is on the laminate 2 delivery side of the roll 1. When somewhat excess water is sprayed at said position, a thin water film deposits between the surface of the roll 1 and that of the laminate 2. By said water film, a polyolefins resin layer 2, onto which embossed pattern is given, is effectively cooled down below its melting point before being released from the pressing down with the embossing roll 1. In addition, the separation of the surface of the resin layer 2 from that of the roll 1 is easily done. Consequently, the deformation of the surface form does not occur even after the release from the pressing down with the embossing roll. Further, since the thickness of the water film becomes uniform, the favorable uniformity of embossed pattern and glossiness of surfaces after embossing result.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for embossing polyolefin laminates suitable for use as industrial materials such as building materials and electrical equipment, and particularly relates to embossing methods for embossing polyolefin laminates suitable for use as industrial materials such as building materials and electrical equipment. The present invention discloses research results regarding effectively imparting a desired embossed pattern to laminated polyolefin resins.

(Prior Art) Laminating thermoplastic resins such as acrylic resins, polyester resins, polyvinyl chloride resins, and polyolefin resins on the surface of sheet-shaped or tubular metal substrates has been widely practiced for some time. Embossed patterns have also been applied to the surface of such well logging bodies.

There are two methods for imparting an embossed pattern to the surface of a laminate: one is to laminate films whose surfaces have been embossed in advance, and the other is to laminate unprocessed films and then emboss them. When such conventional methods are applied to polyolefin/or modified polyolefin (hereinafter collectively referred to as polyolefins) resins, there are problems as described below.

That is, in the former method, polyolefins and metal substrates generally have extremely poor adhesion, so in order to increase the adhesive strength, it is necessary to heat the film made of the polyolefins to a temperature above their melting point to fuse them. Although this is necessary, if the material is heated to a high temperature above its melting point, the embossed pattern previously applied will be deformed due to the heat.

On the other hand, even with the latter method, in order to obtain a preferable processed surface, it is still necessary to heat the polyolefin resin above its melting point before embossing, and in this case, the heating temperature and the resin temperature after passing through the embossing roll are particularly important. It is essential to closely control the temperature, and such temperature control is extremely remote and careful. If the heating temperature is too low, the patterning by the embossing roll will be insufficient; on the other hand, if the heating temperature is too high, the pattern once applied will be deformed immediately after passing through the embossing roll, and in any case, the desired pattern will not be achieved. No embossed pattern was obtained.

Attempts have been made to solve this problem by internally cooling the embossing roll or rapidly cooling the resin layer after embossing, but when using the internal cooling method, the inner surface of the roll is cooled, but the outer surface of the roll is The rolls and resin layer rollers K also had problems because their temperature rose when they came into contact with the high-temperature polyolefin resin. On the other hand, the method of rapidly cooling the resin layer after processing has many technical problems in obtaining an appropriate rapid cooling rate necessary to provide a stable processed surface, and has not yet been put into practical use.

The present inventors proposed a method to solve this problem.
-1lIqt'p,y, it is proposed to carry out embossing in a state where a water film is completely interposed between the surface of the embossing roll and the surface of the laminate.

As a result, even if it is a laminate of polyolefin resins,
Although it was possible to easily and effectively impart an embossed pattern to the surface, the problem remained that the gloss after embossing was not completely uniform.

This invention solves the above problems.

We propose a new embossing method that can easily and effectively apply a desired embossed pattern to the surface of a laminate of polyolefin resins, as well as provide a uniformly glossy finish. The purpose is to do.

(Means for Solving the Problems) As a result of numerous experiments and studies in order to solve the above problems, the inventors have found that during embossing, they use an embossing roll whose surface has good water wettability. The surface of the embossing roll is wetted in advance with water, and a water film is interposed between the surface of the roll and the surface of the laminated polyolefin.

We have obtained knowledge that this method is extremely effective in achieving the intended purpose.

This invention is based on the above knowledge.

That is, the gist of the present invention is directed to the surface of a metal base material.

9. Emboss the surface of a modified polyolefin resin or a laminate made of seven or more layers of polyolefin resin. The laminate is heated to a temperature equal to or higher than the highest melting point of each of the laminated resins, and then the wetting tension of the surface becomes II! r dyn・／
Using an embossing roll of crn or higher, the surface of the embossing roll is wetted in advance, and all embossing is carried out with a water film interposed between the roll surface and the laminate surface. A method for embossing a polyolefin laminate, characterized by:

The modified polyolefin as used in the present invention refers to a polyolefin as described below modified with an unsaturated carboxylic acid, an anhydride thereof, or a derivative thereof. Regarding such degeneration.

Any conventionally known method can be used; 1. Usually, the above-mentioned compound is mixed or grafted onto the polyolefin;
Alternatively, it can be carried out by further changing the acid group or acid anhydride group of the modified polyolefin thus obtained into a derivative thereof.

Polyolefins suitable for use in producing the modified polyolefin include polyethylene and the like.

Copolymers of ethylene and α-olefins other than ethylene, vinyl acetate, (meth)acrylic acid and its esters, and polypropylene.

Examples include copolymers of propylene and α-olefins other than propylene.

And the modified polyolefin resin used in this invention is
In addition to single modified polyolefins and mixtures of modified polyolefins obtained as described above, it also includes mixtures of such modified polyolefins and the above-mentioned polyolefins.

In addition, the unsaturated carboxylic acid or its anhydride to be mixed or grafted to the polyolefin is:

Acrylic acid, methacrylic acid, maleic acid, maleic anhydride, citraconic acid, citraconic anhydride.

Examples include itaconic acid and itaconic anhydride, and unsaturated carboxylic acids or their anhydride derivatives include:
Examples include esterification products of monoepoxy compounds and the above-mentioned acids, reaction products of polymers having groups capable of reacting with these acids in one molecule, and acids.

Furthermore, modified polyolefins contain colorants, stabilizers, and other additives that are commonly used in the past.

Needless to say, it is possible to further incorporate a filler.
Fillers include natural silica such as sand 1 quartz, synthetic silica manufactured by wet or dry methods, natural silicates such as kaolin, mica, Merck, clay, and asbestos, synthetic materials such as calcium silicate, aluminum silicate, etc. Silicates, metal oxides such as alumina, titania, calcium carbonate.

Calcium sulfate and other metal powders such as aluminum and bronze can be used.

Next, on top of the modified polyolefin layer described above.

Polyolefins used when further stacking polyolefin layers include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate. Copolymers such as ethylene-acrylic acid copolymers, ethylene-acrylic ester copolymers and ethylene-methacrylic ester copolymers are particularly advantageously suited.

The unmodified polyolefin mentioned above may contain pigments, heat stabilizers, weathering agents, ultraviolet absorbers, etc. depending on the surface.
It goes without saying that additives commonly used in polyolefins may be included.

Next, as the metal base material used in this invention, when this kind of laminate is used as an industrial material.

Aluminum, iron or galvanized iron are advantageously suitable, and the surface of such substrates may be degreased or
It is effective to perform a chemical conversion treatment such as a 9-phosphate treatment or a chromate treatment in order to increase adhesiveness and corrosion resistance.

Furthermore, in this invention, zinc chromate is added as a rust-preventing pigment to the metal surface that has been treated as described above.

Organic adhesives such as epoxy resins, polyurethane resins, acrylic resins, and polyester resins containing chromates such as strontium chromate can also be applied and baked, thereby further improving adhesion and corrosion resistance. Get better results.

In the present invention, the method for laminating polyolefins on a metal substrate may be any conventionally known method, such as a method of extrusion coating a modified polyolefin on a metal substrate.

Maku further proposes a method of extrusion coating one or more layers of polyolefin on this modified polyolefin, a method of thermo-compression bonding a laminated film having at least one side of the modified polyolefin to metal, and a method of applying powdered polyolefin. There are methods of coating modified polyolefin on a metal substrate heated by K, such as a spray method, fluidized dipping method, and electrostatic fusion method, but these methods have problems such as product stability, weather resistance, and stress crack resistance after processing. Considering various required characteristics, thermocompression bonding of laminated films is particularly suitable.

Embossing is performed on the laminate obtained by laminating modified polyolefin or one or more layers of polyolefin on a metal base material as described above, and this embossing is carried out as follows.

First, at least the laminated resin layer of the laminate is heated to a temperature equal to or higher than the highest melting point of the polyolefins constituting the resin layer. The reason why the heating temperature was set to be higher than the highest melting point of the laminated resin is because it is lower than the temperature of .

This is because not only is it difficult to obtain sufficient adhesive strength, but also it is difficult to obtain a desired processed surface. However, if the heating temperature becomes too high, even if appropriate cooling treatment is performed during embossing as described below, cooling will be insufficient, and the pattern once applied will deform immediately after passing through the embossing roll. Therefore, it is preferable to keep the above-mentioned maximum melting point within a range not exceeding 5 oct.

The pattern is then applied using an embossing roll whose surface has been pre-wetted with water, and in this case it is important to uniformly wet the entire surface of the embossing roll.

In the present invention, the wetting tension on the surface of the embossing roll is high! r dyn・7cm or more, preferably 5Odyn・7
Use an embossing roll of cm or larger. If the wetting tension of the surface of the roll is less than the above range, the gloss of the surface after embossing will be insufficient, which is not preferable.

In addition, the above wet tension is JIS K &? ! , t (wetting test method for polyethylene and polypropylene films)
This is a value measured in accordance with .

Further, as a water sprinkling method, a method of spraying water from a spray nozzle is suitable. If the embossing roll is coated with water in advance in this way, a thin water film will be interposed between the roll surface and the laminate surface during embossing, and the embossed pattern will be created by this water film. Before the polyolefin resin layer is released from the pressure of the embossing roll, it is effectively cooled to below its melting point, and
Since the roll surface and the resin bottle surface can be easily separated, the desired embossed pattern can be obtained without deforming the surface shape even after the pressure is released.

Moreover, when the water wettability of the embossing roll surface is good (when the wetting tension is above II j dyn/crr1), the thickness of the water film formed is uniform, and the uniformity of the embossed pattern and The surface after processing has good gloss.

In addition, it is more advantageous to further cool the laminate by water cooling or the like immediately after the laminate is released from compression in order to obtain the desired embossed pattern.

The water wettability of the embossing roll surface varies depending on the material of the roll surface, but can be controlled by adjusting the roughness of the surface.

Therefore, in order to obtain the desired water wettability, if the surface of the roll is too smooth, it is roughened with sandpaper or the like, and if it is too rough, it is finished with fine sandpaper or the like.

The amount of water that should be used to wet the embossing roll is too high; if there is too much water, the excess water will overflow in front of the embossing roll, and the laminate will cool down before it is processed, resulting in incomplete patterning. 9. On the other hand, if the amount is too small, cooling may be insufficient and the pattern may be deformed after passing through the embossing roll.

The thickness of the water film that should be interposed between the surface of the embossing roll and the surface of the laminate is preferably about 0.0/~O. Approximately 0.0/~! f L / yl
is within the range of

Figure 1 shows 1. A method of sprinkling cooling water onto the embossing roll suitable for properly controlling water ft' is illustrated.

As shown in the figure, the water spraying position is within the control range, and by spraying some excess water at this position,
In addition to wetting the roll surface, excess water can naturally flow down to keep the embossing roll surface naturally wet.

In addition, as shown in FIG. 1, it is also effective to spray some excess water onto the surface of the embossing roll 1 and then adjust the amount of water to an appropriate amount using the squeezing roll 3.

It should be noted that the above-mentioned rows are just examples, and the implementation of this invention is not limited to these methods; it goes without saying that any other method may be used as long as an appropriate amount of water can be obtained. Nor.

According to the present invention, a desired embossed pattern can be stably obtained by interposing a uniform water film between the roll surface, which has good water wettability, and the laminate surface during embossing. This is because the water film effectively cools the laminated resin.

This is because the roll surface and the laminated resin can be easily separated.

(Example) Example 1 Thermosetting epoxy resin is applied to the surface of a galvanized steel sheet treated with zinc sinate! 00 parts by weight or less (expressed simply in parts)
K, 270 parts of zinc chromate and strontium chromate:! rst-blended thermosetting epoxy resin adhesive was applied in an amount of gt/ni'' in terms of dry weight, and then baked at an ambient temperature of 240° C. for 43 seconds.

Thereafter, the surface of the galvanized steel plate coated with this adhesive was coated with modified high-pressure polyethylene (density: 0.9/%/d, melt index: 2.05'/IO", m Water maleic acid graft m: 1200 ppm, melting point: toq°C, ) and high pressure low density polyethylene (density: 0.9λhp/cd, melt index: 09f/10 steel, melting point: 21-°C) were used.

Modified high-pressure polyethylene layer knee Spm and high-pressure low-density polyethylene manufactured by in-die coextrusion method using inflation method at resin temperature: /40°C m: t
A composite film made of o o prys was laminated so that the modified high-pressure polyethylene layer served as the adhesive surface.

The thus obtained laminate was heated so that the temperature of the laminate resin layer was 120° C., and then embossing was performed under the conditions shown in Table 1 below.

The embossing roll used at this time was JIS K&RI6J.
r'I dyn measured by the wettability test method specified in
・/Cr1t was used.

Table 1 shows the evaluation results regarding the condition of the obtained embossed pattern.
It is also shown in . In addition, the water spray level cloudy in Table 1 is shown in Figures 3 to q.
Represented in the position shown in the figure.

The melting point of each laminated resin was measured as follows.

In other words, in differential thermal analysis, a sample of IOη±l da is
After heating and melting at 00C.

Cool and solidify at 10℃/m to tIQ'C, and then cool to 70℃ again.
The temperature was raised to melt at /-, and the peak position on the chart was taken as the melting point.

Further, the embossed state was determined according to the 9th evaluation standard.

A: Target embossing depth (2Q μm).

B: The desired embossing depth can be patterned and the finished gloss is uniform and good.

The pattern was embossed in the desired shape, but the finish was uneven and the gloss was uneven.C: The target embossing depth was 0μ on the entire surface or locally.
Examples 2 to 3 where m) was not obtained Water sprinkling tt - The same procedure as in Example 1 was carried out except for changing the conditions as shown in Table 1. The embossed state was determined in the same manner as in Example I, and the results are shown in Table 1.

Comparative example Wet tension Js dyn@/cm as Nohiro embossing roll
The same procedure as in Example I was carried out except that the amount of water sprinkled was changed as shown in Hi. The embossed state was determined in the same manner as in Example 1 and the results are shown in Table 7.

(Effects of the Invention) According to the method of the present invention, a uniform and clear embossed pattern can be stably and efficiently formed, and a laminate with extremely high commercial value can be obtained.

[Brief explanation of the drawing]

Both FIG. FIGS. 3 to s are schematic diagrams each showing the position of water sprinkling on the embossing roll in an embodiment of the present invention.

Claims (1)

[Claims] (1) When embossing the surface of a laminate in which a modified polyolefin resin or one or more layers of polyolefin resin is laminated on the surface of a metal base material, the laminate is Heating to a temperature higher than the highest temperature of each melting point, then using an embossing roll whose surface has a wetting tension of 45 dyne/cm or higher,
A method for embossing a polyolefin laminate, characterized in that the surface of the embossing roll is pre-wetted and embossing is carried out with a water film interposed between the roll surface and the laminate surface.