JPS5966430A - Preparation of highly adhesive molded polyolefin article - Google Patents

Abstract

PURPOSE:To improve the corona discharge effect sufficiently at an actual production level and obtain the titled composition having improved adhesive properties, by subjecting the surface of a molded polyolefin article to the corona discharge treatment under the respective specific treating conditions and atmosphere. CONSTITUTION:The surface of a continuously running polyolefin film 6 is subjected to the corona discharge treatment under such conditions as to give <=1.8 ratio of change [DELTA(O content/C content)/DELTA(N content/C content)] between the ratio of the O content to the C content (O content/C content) and the ratio of the N content to the C content (N content/C content) in a thin layer (hereinafter abbreviated to the thin layer) within 100Angstrom of the surface to be treated of the film 6 before and after the corona discharge treatment and >=3 ratio between the N content and the C content (N content/C content) in the thin layer after the corona discharge treatment by the high-voltage discharge between an electrode 3 and a metallic drum 1 while blowing a gas, e.g. an inert gas, consisting of the composition other than the air composition from a gas jetting outlet 5 provided in the electrode 3 on the discharge side on the surface of the film 6 to give the aimed molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly adhesive polyolefin molded article, and in particular, the corona discharge treatment effect is fully concerned with the actual production level, and the adhesiveness to the gutter material is improved. The present invention relates to a method for producing a polyolefin molded article.

Corona discharge treatment of plastic films and molded products has been carried out for a long time, and is an indispensable technique for surface modification of polyolefin films such as polyethylene and polypropylene, and its scope of application is increasingly expanding. It is expected that it will go well. In order to deal with this situation, it is necessary to improve the processing efficiency of corona discharge itself and explore its possibilities.Although extensive improvement research has been carried out so far, it is still insufficient. I'm in a situation where I can't say anything.

For example, as a corona discharge treatment method for plastic molded products,
As seen in Japanese Patent Publication No. 48-17747, there is a technique for promoting chemical changes on the discharge surface by supplying an organic solvent to the discharge section, but it is difficult to apply it to molded products where the residual solvent is a barrier. be.

Also Journal of Applied Poly
mer 5science.

Vcl, 15, p% 1865-1875 (1971) describes a technique of performing corona discharge treatment in an inert gas atmosphere, and it is said that the effect of activation or deterioration only due to the surrounding air during treatment is significant. % > 7 Techniques have also been proposed in which the surrounding atmosphere is replaced with, for example, a low-oxygen atmosphere. However, this type of conventional method, for example,
The method of No. 18881 requires a large amount of inert gas, resulting in a cost increase of +1%. Discharge technology) requires a special shield curvature in order to cut off the large amount of air that is entrained in the film, making the equipment complex, but even so, the same complete or almost completely inert atmosphere cannot be guaranteed. However, I had to settle for a low processing level.

The reason why the conventional improvement process m= cannot produce sufficient results can be considered as follows. In other words, the key to increasing processing efficiency is considered to be the gas atmosphere in the discharge processing section, but conventional improvement methods only consider the completion of the gas atmosphere in the processing system or chamber as a problem, and do not This seems to be because the interference caused by the accompanying flow (outside air) on the surface layer of the processed material is not taken into account. Therefore, it is a batch type)
If the processing were carried out in a static state, the above-mentioned problems would be alleviated, but this would significantly reduce industrial productivity and increase market prices, making it practical only for limited applications. Moreover, if we try to obtain a high processing effect through continuous processing as described above, the processing speed will inevitably decrease, but this will damage the surface of the processed object and cause problems such as poor appearance, poor adhesion, and increased blocking. The problem arises. In the conventional corona discharge treatment under atmospheric conditions, the surface of the object to be treated undergoes oxidation and oxidized deterioration products are generated on the surface, so even if the degree of treatment is advanced, the adhesion will not improve beyond some levels. I can't let you.

The present inventors have focused on these circumstances and have been conducting research with the aim of developing a corona discharge treatment method that can provide polyolefin molded products with a high degree of adhesion at an industrial production level. The present invention was made as a result of such research, and its configuration is for performing corona discharge g & embedding by continuously passing a polyolefin molded product through a corona discharge treatment device comprising at least one pair of electrodes facing each other. B. Spraying a single gas or a mixture of gases having a composition other than air onto the surface to be treated, and setting the (-) ratio of 8 or more after corona discharge treatment in a thin layer within 100A of the surface to be treated. There is # in .

Polyolefin molded products to which the method of the present invention can be applied include films, sheets, fibers, pipes, tapes, textiles,
These include long articles such as non-woven fabrics, and the polyolefins constituting these molded articles include a variety of well-known polyolefins, including typical polyolefins for films or sheets, polyethylene, polypropylene, Homopolymers such as polybutene-1, poly-4-methylpentene-1, polyhexene, propylene structural units are 701tf
Examples include various copolymers containing about 4031rj14 or more of propylene monomer units, and polyolefin blends containing about 4031rj14 or more of propylene monomer units. In addition, stabilizers, lubricants, anti-blocking agents, anti-fogging agents, ultraviolet absorbers, flame retardants, clarifying agents, antioxidants, and light-fastening agents are added to molded products made of these polyolefins as necessary. , antistatic agents, dyes, pigments, and other additives may be included, and all additives that do not adversely affect the implementation of corona discharge are included as objects of the present invention, regardless of whether they are used alone or in combination.

In the present invention, the above-mentioned polyolefin molded product is treated,
Surface treatment is carried out by continuously passing the molded article through a corona discharge treatment device comprising at least one pair of %Em facing each other. Electric bodies [Specifically, those with a suitable amount of static electricity composition added from air, those with a suitable amount of static electricity composition added to air, N2, N2, Ar, co2, etc.
Including single or mixed gases such as inert gases such as O2°03, Xe, and Kr, and ionic gases (but excluding air, hereinafter abbreviated as inert gas for convenience) is sprayed. The spraying speed is not particularly limited, but is preferably 11 or more of the feeding speed of the polyolefin molded product. As will be explained in detail later, by strictly specifying the ratio before and after the corona discharge treatment N in a thin layer within 100 layers on the surface to be treated, various materials (e.g. metals; It is possible to obtain polyolefin molded articles having extremely excellent adhesion to Enoki inks, particularly cellulose-based inks, water-based inks, etc.; resins, such as vinylidene chloride homopolymers or copolymers, functional group-containing resins, etc.).

The configuration and effects of the present invention will be clarified below based on the drawings of the embodiments, but the ma and arrangement of the discharge side electrodes, the shape of the cover, etc. shown in the drawings are only representative examples.
Further, since the drawings merely show an example of application to a plastic film, it is within the technical scope of the present invention to change the design on the condition that it does not go against the spirit of these descriptions.

FIG. 1 is a cross-sectional view of the equipment part showing the concept of implementing the present invention, and FIG. 2 is a perspective view showing a part of the discharge side electrode, in which 1 is a metal drum, 2 is an electrode cover, and 8 is a discharge side electrode. A side electrode, 4 a gas supply pipe, 5 a gas outlet, and 6 a running film. That is, the film 6 is introduced from the direction of arrow B into the metal trim 1 rotating in the direction of arrow A, and is further pulled out in the direction of arrow C. , applying a high voltage of several thousand or more at a frequency of several hundred KC/S between the metal trim 1 covered with polyester, epoxy resin, ceramic, chlorosulfonated polyethylene, EP collar, etc. For example, in the natural atmosphere, ozone and nitrogen oxide are generated under the influence of pressure corona generated by On the other hand, in the conventional case, oxidized deterioration products that inhibit adhesion are generated on the film surface due to acid accumulation in the atmosphere, which impedes the surface.However, in the case of this example, corona discharge The electrode cover 2 isolates the entire area from the atmosphere, and the discharge-side electrode 8 is provided with a gas outlet 5 to spray inert gas toward the surface of the film 6. This problem is eliminated, and the corona discharge effect on the surface layer of the film 6 can be maximized.

To explain this situation in more detail, a small amount of accompanying air layer is formed on the surface of the fillet 7 that enters at a fairly high speed along the direction of arrow B, and the atmosphere of the corona discharge part Even if the gas is replaced with an inert gas, the surface of the film 6 itself remains in an atmospheric atmosphere. Therefore, in carrying out the present invention, an inert gas is strongly blown onto the film surface as shown in FIG.
By destructive dispersion in step 18, the film surface is almost completely replaced with inert gas. The flow velocity of the jet stream 8 required to destroy and disperse the entrained air layer 7 cannot be uniformly determined because it varies depending on the shape and size of the object to be treated, the speed of conveyance to the processing equipment, etc., but as a result of experiments, It has been found that it is most preferable to make the addition based on the approach speed of 7 (in other words, the transport speed of the object to be processed). In other words, the flow rate of the inert gas jet is 1 of the conveyance speed of the material to be treated.
10% or more, preferably 10% or more, more preferably 40%
By doing the above, the accompanying air layer 7 can be increased to the extent that there is no substantial problem. The speed at which the material to be processed is carried in is generally about 1 to 500 m/min.

By adopting such conditions, it becomes possible to destroy and disperse the accompanying air layer, and at the same time, it becomes possible to protect the vicinity of the corona discharge part with an inert gas atmosphere. The electrode cover 2 shown here is expected to have a function of protecting the L15 electrode 8 from mechanical noise and suppressing the accompanying flow as much as possible, in addition to its function of maintaining the atmosphere. Become. Therefore, when implementing the present invention, it is sometimes possible to remove the electrode cover 2, but in order to suppress the consumption of inert gas, it is desirable to reconsider its function for maintaining the atmosphere. As shown in FIG. 4, if the lower end (film side) of the cover 2 is squeezed and at the same time inert gas is introduced into the cover 2 from the conduit 10, the gas will be converged along the inner surface of the slope 9 in the direction indicated by the arrow. direction, and a gas curtain effect is exerted at the inlet of the cover 2. That is, the intrusion of the entrained air layer is blocked on the inlet side, and the value of the electrode cover 2 is further improved.

However, regarding the exit side of the film 6 (the right side in Figure 4), the gas inside the cover 2 is discharged along with the traveling film M, so the sealing performance or large 9C intrusion blocking property is determined by the arrangement on the entrance side. Although there is no need to do so, it is meaningful to take the same consideration as on the inlet side in terms of reducing the amount of inert gas consumed as described above. In order to exert the above-mentioned sealing function on the inlet and outlet sides of the helmet cover 2 to the minimum extent possible, it is necessary to discharge onto the film surface at a speed of at least 0.2 times the traveling speed of the film, preferably at least 10 times the traveling speed of the film. It is desirable that the Regarding the ejection speed of the inert gas, only the lower limit side has been described for both the gas ejection port 5 and the inlet/outlet of the cover 2, but there is no practical need to set an upper limit on the ejection speed, and it is based on economic efficiency and the required quality of the final product. It should be decided appropriately based on the balance.

By setting the treatment conditions as described above, the treatment effect of corona discharge is enhanced and the adhesion is significantly improved.
In order to consistently and stably exhibit these effects, we conducted further research based on the belief that it was necessary to quantitatively understand the surface characteristics of the treated object before and after treatment. the result,
■ Ratio of change in the surface ratio of the treated object before and after corona discharge treatment [Δ(Dan)/Δ(N-)], and ■ Similarly, corona discharge heat in a thin layer within 100 layers on the film surface. It has been found that by strictly controlling the post-embedding (te) ratio, it is possible to guarantee the adhesion of the system. By strictly controlling the treatment conditions of corona discharge and the completion of the treatment, for example, metal, Various printing inks (especially cellulose thread ink, water-based ink, etc.)
It is possible to dramatically improve the adhesion to various synthetic resins such as vinylidene chloride-based resins alone or together, and functional group-containing resins. There are many methods for measuring the surface properties as described above, but the most suitable is the ESCA method.

By the way, polyolefin molded articles satisfying the requirement of [(N-) ratio ≧8] stipulated in the present invention can sometimes be obtained under conventional treatment conditions, and can also be obtained by known corona discharge treatment in a nitrogen gas atmosphere. is also possible. However, as explained earlier, in order to secure such a high level of (τ) ratio as mentioned above, large-scale equipment is required, at least with the conventional method that targets continuous processing, making it difficult to put it into practical use on an industrial scale. Met. On the other hand, if the method of the present invention is adopted, the (τ) ratio can be easily increased to 8 or more with relatively simple equipment. On the other hand, there is also a report that the adhesion of a plastic material to each yuzu material is simply determined by the production ratio of N (relative to C) determined by the ESCA method. However, such reports only capture one aspect that affects adhesion. By the way, if you blend an N component into the material, the ratio will increase (!!-), but just adding an antistatic agent or lubricant, which is a N-containing component, will not improve the adhesion, but will actually decrease it. If you think about it, (N-
) It is clear that an increase in the ratio does not directly correlate with adhesion. Therefore, we investigated other factors that affect adhesion and found that the CC value calculated by [△(-)/Δ(-)] was the corona discharge treatment effect, that is, the improvement in adhesion. It was confirmed that the effect was expressed almost accurately, and that those treated so that the value was 1.8 or less exhibited a fairly static level of adhesion to the intended purpose. Incidentally, even if it shows a value of 8 or more, if [Δ(de)/Δ(τ)] exceeds 1.8, the corona discharge treatment effect will be insufficient and it will not be possible to obtain adhesiveness at the 1st grade level. In this sense, the present invention adopts the processing method as shown in the figure, and also when the (τ) ratio is 8 or more, [
Process C so that Δ(dan)/Δ(N-)] is 1.8 or less
C. It is essential to control the conditions.

The present invention is roughly constructed as described above, and in addition to stipulating the "corona discharge heat" conditions, the treatment effect can be constantly evaluated from the amount of change in the (-) ratio and (Te) ratio of the surface layer portion before and after treatment. By understanding this, it has become possible to easily obtain polyolefin molded products tHm with excellent adhesiveness to various materials.

Next, an experimental example will be shown.

The method for evaluating surface properties adopted in the central experiment is as follows.

ill haze: Measured according to JIS-6714 (2) Printing ink adhesive strength Red and white printing was performed with a gravure printing machine using a commercially available printing ink for cellophane.

After printing, it was simultaneously dried in an oil-tight manner, and a commercially available cellophane tape was subjected to a tape peeling test, kneading test, and scratching test using K (manufactured by Chiban Co., Ltd.) 5, ■ Tape peeling test evaluation criteria 5: No peeling at all 4: Ink Peeling area less than about 5 inches 8; Ink peeling area 5 to 10 parts 2; , judge the state of ink falling off with the naked eye) 5: No falling off at all 4: Slight falling on the line, but in practical terms no gaps 8: Falling off in several places on the line with the ``V'' 2: On the line with the ``V'' Many falling off in h1 places 1: Many on the line, also in the width direction) De-dissolving foot Q) Scratching test Place the printed matter on hard paper and scratch the printed area to check for ink falling off.

(3) After printing with laminated strength cellophane ink, it is coated with polyethyleneimine, and after drying, it is laminated with low density polyethylene at 290° C. to a thickness of 80 μm using a bath melt extrusion method.

After aging for 24 hours, the film and polyethylene layer were peeled off and the adhesive strength was measured. The peeling conditions were 180 degree peeling and a speed of f200/min. (4) Other Adhesive Properties The vapor deposition properties of aluminum and the adhesion to vinylidene chloride resin were examined in the same manner as in (2).

EXAMPLE Using isotactic polypropynon (MI=4.0), a biaxially stretched film with a thickness of 20 μm was obtained according to a conventional method and used as a film to be treated. Using this film, a corona discharge treatment was performed while spraying a gas having a specific acid concentration shown in Table 1.

The treatment power was set at 4000 joules/m2, and for comparison, corona discharge treatment was also performed in the same manner in which the atmospheric atmosphere and the treatment atmosphere were simply replaced with nitrogen gas. The processing speed was 20 m/min in both cases.

The adhesion test results for each film are shown in Table 2.

Furthermore, the adhesive strength of the laminated surface of the film printed on the film, laminated with polyethylene (PE), and heated and pressed for 2 seconds using a hot plate at 180° C. was examined, and the results shown in Table 8 were obtained.

As is clear from Tables 1 to 8 of Table 8, not only the corona discharge treatment is performed in the atmospheric atmosphere (A1), but also the case where the discharge system is simply replaced with nitrogen gas (A2.8.4). ) [Δ(de)/Δ(τ]] cannot be suppressed to a low level, resulting in insufficient adhesion.

Especially for A8 and 4, one [Δ(
-)/Δ(de)] is too large, sufficient adhesion cannot be obtained. On the other hand, even if the oxygen concentration is approximated to the conventional example (washing 2.8), if this is sprayed onto the discharge treated surface (
Example: 5.6), the (de) ratio after treatment effectively increases, and [ON Δ(te)/Δ(de)] also has a low value of 1.8 or less. It shows excellent adhesion to other materials. As is clear from these results, in corona discharge treatment, it is insufficient to grasp the 02 concentration in the entire discharge atmosphere, and the accompanying air is 02114M of the discharge surface by breaking and diffusing the layer.
Reducing this is an extremely important requirement.

Although the A4 Comparative Example film seems to be practical, it was confirmed that the overall adhesiveness level was low and that the adhesiveness to cellophane was extremely reduced especially by heat treatment.

Example Film to be treated was biaxially oriented polypropylene film (]]l Boseki Co., Ltd., Byrelin Ilmu〇Tp-2061.
, 20 μm) and perform corona discharge treatment under the conditions shown in Table 4. For the same tests A7 to A12, the amount of nitrogen gas was constant at 3 m3/br-ni per 1 m of film width, and the gas spraying speed in the example was 1.8 m for 7 seconds. Experiments A18 to A16 are examples in which the oxygen concentration on the film surface on the film discharge side was adjusted by changing the gas supply amount, but there was a method in which gas was simply blown into the processing equipment (comparative examples: Ya18 and A14). In this case, the same oxygen concentration cannot be obtained unless 8 to 8 times the amount of gas is supplied compared to the method of spraying gas onto the film surface (Examples: A14 and 15).

Table 5 shows the adhesive properties of each film obtained above.

``61p given ↓ノ'' As is clear from Table 4.5, even if the layers are set so that the processing speed, processing power, and 02 concentration in the atmosphere are approximately the same, simply adding inert gas to the equipment If you just inject (
Comparative Examples: A7 to 9 and 13.14), an accompanying air layer is formed on the film surface and the processing efficiency decreases, so especially [Δ
(-)/Δ(N-)CC] cannot be suppressed to a low level and the adhesion cannot be sufficiently increased, but if an inert gas is sprayed onto the film surface (Examples 10 to 12 and 15.16), the accompanying air layer is destroyed and removed by the ejected current, increasing processing efficiency, making it possible to reduce [Δ(de)/Δ(N-)] to an extremely low level, resulting in improved adhesion to various materials. will improve dramatically.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the implementation status of the present invention, FIG. 2 is a sketch diagram illustrating the discharge side electrode used in the present invention, FIG. 8 is an explanatory diagram showing the state of destruction of the accompanying air layer, and FIG. FIG. 4 is an explanatory diagram showing an example of a Fit pole cover. 1... Metal drum 2... Electrode cover 8...
Discharge side electrode 5...Gas outlet 6...Film Applicant Toyobo Co., Ltd. Figure 1 Figure 4 1000-Series Neighborhood City Authorization (Spontaneous) December 23, 1981 [J 1, Incident Indication] 1981 Patent Application No. 178126 2, Name of the invention: Method for manufacturing highly adhesive polyolefin molded products 3, Relationship with 11 amendments Patent applicant: 2-2-8 Dojimahama, Kita-ku, Osaka (316) Toyobo Co., Ltd. Representative Maki Uno 4, Agent Shinko Building, 2-3-7 Dojima, Kita-ku, Osaka 530 Column 6 of Detailed Description of the Invention J, Details of Contents of Amendment-1 of the Specification Insert the following text between lines 19 and 20 on page 16.

Claims (1)

[Claims] (1) When corona discharge treatment is performed by continuously passing a polyolefin molded product through a corona discharge treatment device comprising at least one pair of electrodes facing each other, a single or Ratio of amount of change before and after mixed Rona discharge treatment [(Total characteristic mold in a thin layer within 100λ of the surface of the object to be treated?) Method for producing a transparent polyolefin molded product.