JPS63299915A - Surface treatment of roll for heat drawing of polymeric film - Google Patents

Abstract

PURPOSE:To prevent occurrence of surface defects in a polymeric film to be drawn, by coating the surface of a roll by which a heated polymer film is continuously drawn with a chrome oxide type ceramic in a specific thickness and finishing it to a mirror surface. CONSTITUTION:Raw materials of polymeric film are thermoplastic plastics such as polyesters, polypropylene or polyvinyl chloride. Chrome oxide type ceramics coated by means of plasma flame spray on the surface part of a roll by which this polymer film is continuously drawn under heated condition, consist of about 94%, preferably 96% or more Cr2O3 and the remainder TiO2 by wt. ratio and the thickness is 0.25-0.5mm. Then, finishing is carried out by grinding in such a way that the surface roughness is 0.05-0.20muRa mirror surface, and the thickness after grinding is about 0.15-0.35mm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to metal rolls, and more specifically, the present invention relates to metal rolls, and more specifically, for example, continuous stretching of a polymeric thermoplastic film such as polyester in a heated state. The present invention relates to a method for processing or treating the surface of a metal roll suitable for processing the surface of a metal roll.

[Prior art]

For example, stretched films made of thermoplastic polyester obtained by condensing ethylene glycol and terephthalic acid have excellent mechanical, electrical, and thermal properties, and have recently been used for metal deposition applications, audio, It is well known that it is widely used as a suitable material for bell sounds in videos, magnetic tapes for sickle paintings, electrical insulation purposes, photosensitive materials, and other suitable materials.

However, this type of film, which is normally produced by continuously stretching in a heated state using metal (steel) rolls, has problems due to adhesion to the surface of the rolls during the stretching process. It is prone to spotting, abrasions, and scratches, and these defects and the resulting reduction in surface properties lead to deterioration of performance, workability, and appearance in the various applications mentioned above. Therefore, there was an inconvenience and problem that the product value was significantly reduced.

By the way, heating, stretching, and surface conditioning of polyester, polypropylene, and other polymeric thermoplastic films are generally performed by heating and maintaining the film at a predetermined high temperature from the inside using appropriate heating means such as electric heat or superheated steam as a heat medium. The stretching process is carried out continuously by passing the film between a plurality of rotating metal rolls, but the adhesion of these films to the stretching rolls mainly depends on the material or characteristics of the roll surface. A wide variety of methods have been proposed and implemented to reduce this undesirable tackiness, or in other words, to improve its non-tackiness.Typical methods include sandblasting, Teflon coating, etc. A method for longitudinally stretching a polyester film characterized by I coating processing, or a combination of hard chrome plating and sandblasting or mirror finishing, and further coating with specified ceramics (see 'I Koshoq-! & 4JJ Publications) ) etc. are known.

However, among these conventionally known and publicly used techniques, the method of increasing the roughness of the metal roll surface by sandblasting is effective in reducing the adhesiveness of the film and preventing the occurrence of adhesive unevenness. On the other hand, there is a high possibility that surface defects such as abrasions and scratches may occur on the film during stretching, and films coated with l-Tear-I can be expected to have good non-adhesive properties due to their properties. However, since the coating lacks abrasion resistance, there is a problem in its adoption in terms of durability.

Furthermore, hard chrome plating combined with sandblasting is more durable than mirror-finishing in terms of non-adhesive properties, but surface defects such as scratches and scratches may occur. This is extremely likely to occur, and when combined with the other mirror finishing, the non-adhesion is insufficient, so it cannot be used at relatively low temperatures of about 700~/θ0C (near the secondary dislocation point of these polymer films) or higher. Significant problems are observed.

As is clear from the description of the specification, the ceramics disclosed in the above-mentioned Japanese Patent Publication No. 94T666 mainly contain alumina (A/z
Os 90'Ir or higher), Zirconia (Zr0290
4 or more), zircon (Zr0z 60~1.j%, 5
10x! 0-3! H) is recommended, and is significantly more effective in terms of non-adhesiveness and prevention of uneven adhesion, scratches, and abrasions than those with a mirror finish and sandblasted hard chrome plating. However, the maximum allowable heating temperature of the drawing roll is at most /!
The temperature should be approximately O0C, preferably within the range of 1000 to 30°C, and higher temperatures may cause damage to the ceramic coating due to surface defects such as abrasions, scratches, and transfer scratches, as well as differences in thermal expansion coefficients. The disadvantage is that it is not possible due to the possibility of cracks occurring and the destruction of 10-meters.
Defects are recognized.

[Problem that the invention seeks to solve]

As mentioned above, the adhesion of this type of polymer film to the metal stretching roll surface can be suppressed, and uneven adhesion, scratches, and
Compared to sandblasting, Teflon coating, or hard chrome plating, ceramic coatings are currently the least effective means and methods for preventing scratches and other surface defects. There is no doubt that this is the most appropriate, certain, promising, and wise thing to do.

However, the currently known and publicly used ceramic coating methods still lack appropriateness in terms of the selection of ceramic materials used, various conditions related to coating construction, and other aspects, and are not necessarily satisfactory. Specifically, surface defects such as uneven spots, scratches, and scratches due to film adhesion have not been achieved.
In order to avoid cracks, peeling, and other disadvantages that occur early in the ceramic coating, the heating temperature of the stretching roll must be kept below approximately /j-00C, which is a disadvantage and problem.

[Means to solve the problem]

The present invention was made in view of the above circumstances and in response to the strong actual and latent demands of related technical fields and industry. This type of polymer film is expected to exhibit excellent non-adhesive properties even when stretched, and is free from the various defects mentioned above.
It can be obtained economically, and the durability of the heated stretching roll itself can be significantly extended and improved.
The object of the present invention is to provide a surface treatment method or the roll itself.

The inventors of this application have accumulated over many years various ceramic coating operations and related research,
Based on the acquired materials, experience, and knowledge, we have learned that, in particular, we have been able to detect early cracks and peeling of the ceramic top coat that is thermally sprayed and formed on the surface of the roll for heating and stretching this type of polymer film, as well as damage to the roll itself and damage to the roll itself. Inconveniences such as film adhesion during hot stretching are caused by the difference in thermal expansion coefficient and thermal conductivity between the roll base material and the 7-layer ζx layer, the coating thickness and finish of the ceramic, and the processed surface roughness. We have long been convinced that there is an extremely important relationship between the two, and therefore, in the development and research of a new heated stretching roll for polymeric films and its surface treatment method, which is intended to achieve the above objectives, we will use various known and publicly used ceramics. After taking into full consideration the results of some basic preliminary tests conducted in advance and the physical properties of each ceramic, we have concluded that, at least at this point in time, it is the most suitable and promising ceramic for top coats. Chromium oxide-based ceramics (in terms of weight percentage, for example, Crz03 is about Wadah or more, and the remainder is mainly Ti0z), which has not been given much importance or attention in the past, and is representative of a very suitable control example. Considering the fact that the excellent performance has been proven and evaluated in a large number of usage records and is currently widely used in practical use, the two types of alumina-based alone and the combination of this alumina-based and zirconia-based as exemplified in Part 1. Ceramics made by laminating
The present invention was completed based on the knowledge obtained through various experiments, systematic comparative tests, and careful studies and considerations.

That is, in the surface treatment method of a roll for heating and stretching a polymer film according to the present invention, at least the surface portion of the roll on which the polymer film is continuously and substantially stretched in a heated state is treated by a method such as a Gradama thermal spraying method. The basic feature is that after being coated with the chromium oxide ceramic to a predetermined thickness via a chromium oxide ceramic, it is finished to a mirror surface by grinding.

The polymer film includes one made of thermoplastic plastics such as polyester, polypropylene, or polyvinyl chloride, and the chromium oxide ceramic has a weight percentage of about 9 g of Cr2bs.
Preferably, it is more than 9g, with the remainder being T10g,
The thickness of the coated chromium oxide ceramic is 0. 〇〜θj mm sThickness after grinding is 0/!
~03 ohm, and this surface is coated with 006
In a preferred embodiment, the mirror surface is finished by grinding to a mirror surface having a roughness in the range of N (21 μRa).

[Example and comparative example]

Each ceramic layer sprayed onto the surface of the metal base material is normally formed to a thickness of 0.06 mm to 0.0 mm, but if the surface is subjected to grinding, the coating should be sprayed to a thickness of at least θJ mm. is generally accepted as necessary.

By the way, due to the nature and use of the roll for heating and stretching polymer films, which is the subject of the present invention, if the surface is ground by grinding and the thickness of the ceramic coating is thin, spots may appear on the film. On the other hand, if it is too thick, it will lead to poor thermal conductivity and reduced thermal efficiency, leading to early cracking and peeling of the ceramic coating, and even the destruction of the roll itself, which can lead to serious accidents. There is a risk of inviting

Therefore, in the basic preliminary test described above, the inventors of the present application also conducted a test to determine the appropriate thickness range for the ceramic layer to be formed, and the preferred thickness is around θ or θ2jmrn We have come to the conclusion that this is the case.

Therefore, in order to first confirm the effect of the surface treatment method of a heated drawing roll according to the present invention on improving heat resistance properties, specifically crack resistance, peeling resistance, etc., as shown in Table 1, Necessary comparative tests were conducted on the Examples and Control Examples.

[Preparation of sample]

In Table 1, four types of ceramic coatings with different chemical compositions, numbered No. 1 to No. 4, are applied to the outer peripheral surfaces of five 5S41 iθmmφ hollow rolls having approximately the same wall thickness and length. As is clear from the photograph and FIG. 1, before welding and forming the welds in each axial direction with a width of about 700 mm, the entire outer peripheral surface was thoroughly degreased with an organic solvent in advance. For example, Na36~4t≦
Blasting with grid-sized alundum (alumina abrasive grains) (pressure approx. 4t~7kiL/Cx")
Undercoat treatment was carried out via . Then, as specified in Table 1 and FIG.
The alloy powder was sprayed using a conventional plasma spraying method using a plasma flame spraying machine (IOMB type) manufactured by Metco, USA.
An undercoat was deposited and formed to a uniform predetermined thickness of about 700 μm), and for No. 4 control example, zirconia (ZnOz) powder stabilized with Yztriya (YzOs) was added as above. Similarly, after spraying from the nozzle of a plasma spray gun to form a middle coat of ceramics (film thickness approximately /θθμm), the roll is rotated in the same manner as above to coat the undercoat or middle coat. As a top coat, chromium oxide-based or alumina-based ceramic powder was coated using the plasma spraying machine in the order and arrangement shown in Figure 1, so that the desired coating thickness was approximately 300 μm. , respectively, were thermally sprayed.

Each of the top coats formed in this way is ground using a grinder, first with a diamond wheel (No. 2ZO) and then with a GC foil (No. ixH) to the final film thickness as illustrated in Table 1. Finished. The average measured value of the outer surface roughness obtained for each top coat made of chromium oxide ceramics for No. 1 Example and alumina ceramics for No. 2 to No. 4 Control Examples after these final grinding is as follows: 007~θ/7pR respectively
a and 0. jO~0. tOttRh [Comparative test of heat resistance properties] A. As mentioned above, five samples made almost identically,
That is, for each hollow roll (see photo 1),
In order to obtain qualitative results in a short period of time, we conducted an accelerated test by repeating rapid heating and cooling as shown in Figure 2 to determine the presence or absence of cracks and peeling phenomena in the coating, and the extent of their progress. Examined.

(1) A hollow roll is rotated at a constant speed and heated from the inside using a gas burner (see Photo 2). During heating, the temperature is measured with a contact thermometer to ensure that the entire outer circumferential surface of the roll is constantly Great care was taken to maintain heating at a substantially uniform temperature.

(2) The heating temperature is approximately 70' (:/min,
Cooling was performed by interrupting heating with one burner and blowing room temperature air over the entire outer surface.

B. Photo 3 shows the results of each of these hollow rolls after the test.
Photos 4 and 5 are enlarged detailed photos that illustrate the appearance of the book (state of the coating).

(1) For No. 1 Example, the heating shown in FIG.
Repeated cooling cycle test 70 times (/!Omin
) The above tests were carried out continuously, but as is clear from Photo 4, no cracks, peeling, or other phenomena in the coating could be observed, at least to the naked eye.

This is not due to the fact that chromium oxide ceramics have a higher coefficient of thermal expansion than the alumina ceramics selected as a control example, so the scales follow the thermal expansion of the base material, that is, the 5S41 roll. I think so.

(2) Na, For the 2 control example, the heating and cooling cycle shown in Figure 2 was repeated twice (jOmin), and as can be seen from Photo 4 showing the results, slight cracks were generated throughout. ing.

The alumina ceramics in this case have a larger particle size (
/! ~! It seems that the effect of having a thickness of 3 μm) appears. It should be noted that if the heating conditions for the sample (including the maximum temperature) are moderate, it is quite possible that no cracks will occur.

(3) The No. 3 control example is the same as the Nn*2 control example, as can be pointed out from Photo 5 showing the appearance state after repeating the heating/cooling cycle once (30 min). Compared to the control example, the degree of cracking is slightly H.

However, the maximum temperature is about 2j00C, and the heating rate is about 20℃/
Although the conditions were more severe than the actual conditions of use (min.), it can be recognized that the degree of cracking that occurred was milder than that seen in conventional heated stretching rolls.

This is because, in addition to the buffering effect of the Ni-Cr alloy used in the undercoat, the grain size of the alumina ceramic used in this control example is approximately one rank larger than that of the commonly used alumina ceramic. This is probably due to the buffering effect caused by the thickness of 100 μm.

(4) No, 4 control cases, No * 2 and N
o, 3 different from the control example, 7 heating and cooling cycles (/j
min), very noticeable hexagonal cracks had already occurred on the entire surface (see Photo 5).

In this case, zirconia-based ceramics as the middle coat forms a film with high porosity, so we thought it would be effective for thermal buffering, so we chose it, but the expected effect was not sufficiently achieved. It seems that it was not. On the contrary, I think that the property of zirconia-based ceramics, which has a high coefficient of thermal expansion, may have the opposite effect and may be a friend.

(5) From the results of the laboratory heat-resistant comparison test outlined above, the heat-resistant ceramics that should be coated on the heated stretching roll surface are chromium oxide ceramics, specifically =! It was confirmed that it was the best in terms of crack resistance and peeling resistance against high temperatures of about θ°C.

[Practical test and effects of the invention]

As mentioned above, the inventors of the present application have selected the types of coating ceramics that have been concluded to be optimal at least at the present time, based on the results of various tests conducted in-house.
The practicality of the surface treatment method for a roll for hot stretching of a polymer film, including its composition, appropriate coating thickness, etc. The use of this type of roll is necessary for final confirmation and determination of its excellent effects such as tackiness, uneven adhesion, abrasions, scratches, and other surface defects, and long-term durability. We provided the actual product to polymer film manufacturers and had them put it into practical use.

Based on the results, the one specified in the claims of the present invention is the most preferred and effective one, and the conventional one is:
Generally, rolls become unusable after two to three months at most, but it has been proven that the rolls according to the present invention can be used for more than seven to two years.

[Brief explanation of drawings]

FIG. 1 shows the locations on the roll surface to be thermally sprayed with Examples and Control Examples of the present invention and the structure of their coatings, in order to confirm the effect of improving the heat resistance properties of the surface treatment method for heated stretching rolls according to the present invention. Figure 2 is a diagram showing the relationship between the temperature and time of the surface of the film heated and cooled in the above test, and a photograph of the figure/~! These are photographs illustrating the appearance of the sample (hollow roll) prepared for the heating and cooling tests before the test, during the test, and after the test, respectively. Applicant: Japan Coating Industry Co., Ltd. Agent
Yoshio Nagaishi ■Hoshi Ichiwata
1 to Moromit/l Peng Rourin II (Togen Proceedings Amendment Book (Method) 1986 Cog Date/Indication of Case 1988 Patent Application No. 13470r
No. 3 Relationship with the case of the person making the amendment Patent applicant Nagasu Akira Shitoshi Address Amagasaki Nagasu Nishi-dori/chome 3 xgJ & Name
Japan Coating Industry Co., Ltd. Representative: Gen Kuwatani Agent: Postal code: 6jO Address: 6-6 Da-chome, Aioi-cho, Chuo-ku, Kobe City, -
Yo, the date of the amendment order: Showa 6λ? Month ! Date (Delivery date t2.J", = j) --62,g, 26 Z Contents of amendment ■ Relationship diagram of ", photo/Nj is 10 from line 14 to line 17 of page 2 of specification ．It is a photograph.'' Kim, changed to ``It is a relationship diagram.'' ■ Photo l~! Delete. ? List of attached documents

Claims (5)

[Claims] (1) In a metal roll that continuously stretches a polymer film in a heated state, at least the surface portion of the roll where stretching is substantially performed is coated with chromium oxide ceramics using a plasma spraying method or the like. 1. A method for surface treatment of a roll for heating and stretching a polymer film, characterized in that the roll is then polished to a mirror finish. (2) Heat stretching of the polymer film according to claim 1, wherein the polymer film is made of thermoplastics such as polyester, polypropylene, or polyvinyl chloride. surface treatment method for rolls. (3) Chromium oxide ceramics have a weight percentage of Cr_
2O_3 is approximately 94%, preferably 96% or more, and the remainder is T
Claim 1 characterized in that it is iO_2.
A method for surface treatment of a roll for heating and stretching a polymer film according to item 1 or 2. (4) The thickness of the chromium oxide ceramic coated by plasma spraying was 0.25 to 0.5 mm, and the thickness after grinding was about 0.15 to 0.35 mm. A method for surface treating a roll for heating and stretching a polymer film according to any one of claims 1 to 3, characterized in that: (5) The surface of the coated chromium oxide ceramics is
Heating of a polymer film according to any one of claims 1 to 4, characterized in that it is finished to a mirror surface with a roughness in the range of 0.05 to 0.20 μR_a by grinding. Surface treatment method for stretching rolls.