JP2006212915A - Method and apparatus for producing laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a laminate excellent in appearance in which the occurrence of a crater in the surface of a resin film laminated on a substrate. <P>SOLUTION: In a method for producing the laminate, when the laminate 28 is produced by nipping/laminating the substrate 24 and the resin film 12 by a nip roller 18 and a cooling roller 16 while the surface of the traveling beltlike substrate 24 is coated with the molten thermoplastic resin film 12 discharged from an extrusion die 14, the substrate 24 and the resin film 12 are nipped so that the thickness of the resin film 12 in the produced laminate 28 is 20-85% of the thickness of the resin film 12 at the nip position where the resin film 12 is laminated on the substrate 24, and the amount of the resin film 12 passing through the nip position M is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminate manufacturing method and apparatus, and more particularly, to a technique for suppressing generation of craters generated on a resin film surface of a laminate.

  For the production of laminates such as photographic printing paper substrates, the traveling substrate is coated with a resin film of a thermoplastic resin such as polyolefin discharged from an extrusion die at the nip position between the nip roller and the cooling roller. In addition, an extrusion laminating method (also referred to as an extrusion coating method) in which a resin film is laminated on a base material by nip and pressure bonding is widely adopted.

  In the production of this laminate, fine pores (hereinafter referred to as “crater”) may be formed on the surface of the resin film laminated on the substrate. When the number of craters is large, not only the appearance of the product is impaired, but also when the laminate is used as a support for photographic paper, for example, the glossiness is also lowered, so that the value of the product is remarkably lowered.

  The occurrence of craters is said to be related to conditions such as the line speed, the resin film thickness, the discharge temperature of the resin discharged from the die, and the nip pressure for nip, but the cause has not yet been clarified.

Prior art that disclosed measures for preventing the occurrence of craters includes, for example, a countermeasure using a resin composition in which a polyester resin and a polyethylene resin are mixed, focusing on the resin (Patent Document 1), and focusing on the base material. Focusing on countermeasures for laminating a resin film immediately after calendering the material with a metal roll or synthetic roll (Patent Document 2) There is a countermeasure (Patent Document 3) designed to do so.
JP-A-8-286319 JP-A-4-81836 JP-A-8-254789

  However, although the crater generation prevention measures of Patent Documents 1 to 3 described above are effective as they are, the types of laminates that can be produced while exhibiting the effects are limited, and are applicable to various types of laminates. There is a problem that you can not.

  The present invention has been made in view of such circumstances, and it is possible to produce a laminate with less surface crater generation and excellent surface appearance, which is laminated (bonded) to a substrate. It is an object of the present invention to provide a laminate manufacturing method and apparatus applicable regardless of the type of laminate to be manufactured.

  According to a first aspect of the present invention, in order to achieve the above object, the surface of the traveling belt-like substrate is covered with a resin film of a thermoplastic resin discharged in a molten state from a die, and the substrate is formed by a nip roller and a cooling roller. In the method for producing a laminate in which the resin film is bonded together by nip, the film thickness of the resin film in the laminate manufactured by the manufacturing method is the film of the resin film at the nip position where the film is bonded to the substrate. There is provided a method for producing a laminate, characterized in that the nip is performed so as to be in a range of 20 to 85% of the thickness, and the passing amount of the resin film passing through the nip position is reduced.

  According to the present invention, a nip is performed so that the thickness of the resin film in the manufactured laminate is in the range of 20 to 85% of the thickness of the resin film at the nip position bonded to the substrate, By restricting the amount of resin film passing through the nip position, an appropriate reservoir portion of the resin film is formed on the upstream side of the nip position. Laminates can be produced. Moreover, the present invention can be applied regardless of the type of laminate to be produced.

  When the surface roughness of the base material is represented by the average periodic length of irregularities present on the surface of the base material, the average periodic length is 50 μm or less, or 100 μm or more. It is characterized by that.

  In addition to the invention of claim 1, the use of a substrate having a surface roughness with an average period length defined in claim 2 can further suppress the occurrence of craters.

  A third aspect of the present invention is characterized in that, in the first or second aspect, when the surface roughness of the base material is expressed by the height difference of the unevenness existing on the surface of the base material, the maximum height difference is 5 μm or less. To do.

  In addition to the invention of claim 1 or claim 2, if a substrate having the surface roughness defined in claim 3 is used, generation of craters can be further suppressed.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the laminate is a photographic paper support.

  The laminate production method of the present invention is particularly effective when producing a photographic paper support as a laminate.

  According to a fifth aspect of the present invention, in order to achieve the above object, the surface of the traveling belt-like base material is covered with a resin film of a thermoplastic resin discharged in a molten state from a die, and the base material is formed by a nip roller and a cooling roller. And a resin film in a laminate manufacturing apparatus, the first film thickness measuring means for measuring the film thickness of the resin film at the nip position bonded to the base material, and the laminate Adjusting the nip pressure between the nip between the nip roller and the cooling roller based on the measurement results of the second film thickness measuring means for measuring the film thickness of the resin film and the first and second film thickness measuring means; And a controller for controlling a passing amount of the resin film passing through the nip position.

  Claim 5 comprises the method invention of claim 1 as an apparatus invention, the film thickness of the resin film at the nip position bonded to the substrate measured by the first film thickness measuring means, and the second film Based on the thickness of the resin film in the laminate measured by the thickness measuring means, the nip pressure between the nip between the nip roller and the cooling roller is adjusted to control the amount of the resin film passing through the nip position. And a controller. As a result, it is possible to produce a laminate with less surface crater generation and excellent surface appearance, and the present invention can be applied regardless of the type of laminate to be produced.

  As described above, according to the method and apparatus for producing a laminate according to the present invention, a laminate having an excellent surface appearance with less craters generated on the surface of a resin film laminated (bonded) to a substrate is produced. It can be applied regardless of the type of laminate to be manufactured.

  Hereinafter, preferred embodiments of a method and apparatus for producing a laminate according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall configuration diagram of a laminate manufacturing apparatus 10 according to the present invention.

  As shown in FIG. 1, a cooling roller 16 and a nip roller 18 are arranged in parallel and adjacent to each other below the extrusion die 14 from which the molten thermoplastic resin film 12 is extruded. On the opposite side of the nip roller 18, a peeling roller 20 is disposed adjacent to and parallel to the cooling roller 16. Further, a backup roller 22 is provided on the opposite side of the cooling roller 16 across the nip roller 18. The traveling belt-like base material 24 is nipped while being covered with the resin film 12 extruded from the extrusion die 14 at a nip position M where the cooling roller 16 and the nip roller 18 are in contact, and the base material 24 and the resin film 12 are separated. It is pasted together. The base material 24 to which the resin film 12 is bonded travels while the resin film side is in contact with the surface of the cooling roller 16 and is cooled, and is peeled off from the cooling roller 16 by the peeling roller 20. Thereby, the laminate 28 is manufactured.

  The nip roller 18 and the backup roller 22 are respectively provided with pressing force adjusting devices 30 and 30 for adjusting the nip pressure by controlling the pressing force with respect to the cooling roller 16, and are controlled by a controller 32 which will be described later. As the pressing force adjusting device 30, for example, a hydraulic cylinder or the like can be used.

  Further, the laminate manufacturing apparatus 10 is provided with first film thickness measuring means 34 for measuring the film thickness of the resin film 12 at the nip position M bonded to the base material 24. As shown in FIG. 2, the first film thickness measuring means 34 mainly obtains a measuring device 38 for measuring the gap amount G between the cooling roller 16 and the nip roller 18 and a gap amount G measured by the measuring device 38 in advance. The computer 40 calculates the thickness of the resin film 12 at the nip position M from the thickness of the base material 24.

  The measuring device 38 mainly includes disk-shaped discs 42 and 44 attached to the rotating shafts 16A and 18A of the cooling roller 16 and the nip roller 18, respectively, and two CCDs for imaging the peripheral portions of the respective discs 42 and 44. The cameras 46 and 48, and two FFT analyzers 50 and 52 for analyzing the frequency of the vibrations of the cooling roller 16 and the nip roller 18 respectively. In this case, the disks 42 and 44 of the cooling roller 16 and the nip roller 18 may be imaged by one CCD camera. However, since the imaging field is enlarged and the imaging accuracy is lowered, two CCD cameras 46 and 48 are used. It is preferable to do. Further, the diameters of the respective disks 42 and 44 are formed so as to coincide with the diameters of the cooling roller 16 and the nip roller 18.

  In order to measure the thickness of the resin film 12 at the nip position M by the first film thickness measuring means 34, the distance between the disks 42 and 44 is measured by the CCD cameras 46 and 48, and the FFT analyzers 50 and 52 are used. Vibrations at the time of rotation of the cooling roller 16 and the nip roller 18 are measured, and each measurement data is input to the computer 40. The computer 40 calibrates these data, calculates the gap amount G when the cooling roller 16 and the nip roller 18 are rotated, and subtracts the thickness of the base material 24 measured in advance from the gap amount G, thereby obtaining the nip position. The thickness of the resin film 12 at M is calculated. In the present embodiment, the first film thickness measuring means 34 is configured as described above. However, if there is a film thickness measuring sensor that can directly measure the resin film thickness accurately in front of the nip position M, it is used. It may be used.

  Further, in the vicinity of the resin film surface side of the laminate 28 peeled off by the peeling roller 20, there is a non-contact type second film thickness measuring means 36 for measuring the film thickness of the resin film 12 of the laminate 28. Provided. As the second film thickness measuring means 36, an interference type for measuring the film thickness from interference light data generated by the optical path difference of the reflected light from the interface between the resin film 12 and the substrate 24 can be suitably used. The measurement values measured by the first and second film thickness measuring units 34 and 36 are sequentially input to the controller 32. The controller 32 includes a film thickness ratio (B / A) of the film thickness value (B) measured by the second film thickness sensor 36 to the film thickness value (A) measured by the first film thickness sensor 34. X100%] is provided, and a constant film thickness ratio (for example, 80%) is set as a set value in the film thickness ratio in the range of 20 to 85%. This set value can be changed by an input from an input means (not shown) of the controller 32. The controller 32 adjusts the pressing force of the nip roller 18 and the backup roller 22 so that the film thickness ratio calculated by the calculation unit based on the measurement values of the first and second film thickness sensors 34 and 36 is 80%. The apparatus 30 is controlled.

  Next, the manufacturing method which manufactures the laminate 28 using the manufacturing apparatus 10 comprised as mentioned above is demonstrated.

  The thermoplastic resin film 12 discharged in a molten state from the extrusion die 14 and the traveling base material 24 merge at the nip position M, and the nip roller 18 and the cooling roller 16 nip the resin film 12 and the base material 24 together. To do. Thereby, the resin film 12 is bonded to the base material 24. The base material 24 to which the resin film is bonded is conveyed to the peeling roller 20 while the resin film surface is in contact with the cooling roller 16. Thereby, the resin film 12 is cooled. The substrate 24 having the resin film cooled is peeled off by the peeling roller 20. Thereby, the laminate 28 is manufactured.

  In manufacturing the laminate 28, the film thickness (A) of the resin film 12 at the nip position M bonded to the base material 24 is measured by the first film thickness measuring unit 34, and the resin of the laminate 28 is used. The film thickness (B) of the film 12 is measured by the second film thickness measuring means 36. Then, the measured values of the first and second film thickness measuring means 34 and 36 are input to the controller 32. The controller 32 calculates the film thickness ratio [(B / A) × 100%] in the calculation unit, compares the calculated value with a set value (for example, 80%), and the calculated value and the set value are matched. Further, the passing amount of the resin film 12 passing through the nip position M is appropriately reduced by feedback control for adjusting the pressing force of the pressing force adjusting device 30 of the nip roller 18 and the backup roller 22.

  In this way, the resin film 12 discharged in the molten state from the extrusion die 14 is reduced in passage amount at the nip position M, so that the resin film 12 accumulates immediately upstream of the nip position M as shown in FIG. A portion 12A (a portion where the resin film 12 swells) is formed. Even if the surface of the base material 24 (surface on the side where it is combined with the resin film 12) is uneven due to the action of the pool portion 12A, the concave portion is reflected on the surface of the resin film 12 (surface on the side in contact with the cooling roll 16) and becomes a crater. There is nothing. Thereby, it is possible to produce a laminate 28 with less craters on the resin film surface and excellent surface appearance. Moreover, the method for producing a laminate according to the present invention can be applied regardless of the type of the laminate 28 to be produced.

  If the reservoir 12A is too large or too small, the surface appearance of the laminate 28 is adversely affected, and the amount of the resin film 12 passing through the nip position M is reduced so that the reservoir 12A has an appropriate size. This is very important. Then, the present inventor diligently studied the amount of passage of the resin film 12 squeezed at the nip position M from such a viewpoint, and the film thickness of the resin film 12 in the manufactured laminate 28 is the nip bonded to the substrate. The passing amount of the resin film 12 passing through the nip position M is reduced so as to be in the range of 20 to 85% of the film thickness of the resin film 12 at the position. This is because when the reservoir 12A is formed so large that the film thickness ratio is less than 20%, the reservoir 12A becomes unstable, and the film thickness distribution on the resin film surface of the manufactured laminate 28 increases. It is. The lower limit of the film thickness ratio of 20% is considered to be a limit in terms of equipment. On the other hand, it is because the effect of reducing the number of occurrences of craters cannot be sufficiently exhibited in a pool portion that is so small that the film thickness ratio exceeds 85%. The film thickness ratio of 20 to 85% is a value including a reduction in film thickness due to cooling of the resin film 12 by the cooling roll 16. In FIG. 3, the size of the reservoir portion 12A is exaggerated, but the resin film 12 itself has a thickness on the order of microns, and the swelling of the reservoir portion 12A is increased by setting the film thickness ratio to 20 to 85%. This change is difficult to distinguish with the naked eye.

In order to reduce the occurrence of craters on the resin film surface of the laminate 28, the surface roughness of the substrate 24 bonded to the resin film 12 satisfies a predetermined surface roughness in addition to the above-described film thickness ratio. Is preferred. That is, when the surface roughness of the substrate 24 is expressed by the average period length of the unevenness present on the substrate surface, the average period length is preferably 50 μm or less, or 100 μm or more. Furthermore, when the surface roughness of the base material 24 is expressed by the height difference (H) of the unevenness existing on the surface of the base material, the maximum height difference (H _max ) is preferably 5 μm or less.

  As shown in FIG. 4, the pitch P1 from the concave portion A to the concave portion A or the pitch P2 from the convex portion B to the convex portion B is short and fine asperities having an average period length of 50 μm or less. In the case of repetition, or in the case of repetition of broad unevenness where the pitch P1 from the concave portion A to the concave portion A or the pitch P2 from the convex portion B to the convex portion B is long such that the average period length is 100 μm or more, It tends to be difficult to be reflected on the surface (surface on the cooling roller side) of the resin film on which the unevenness of the base material is bonded. On the other hand, when the average period length exceeds 50 μm and is less than 100 μm, the unevenness of the base material 24 is easily reflected on the surface of the resin film to which the substrate 24 is bonded, and the reflection of the concave portion appears as a crater on the resin film surface. Therefore, if the base material 24 having a surface roughness with an average period length of 50 μm or less or 100 μm or more is used, generation of craters can be suppressed accordingly. A center line was drawn to the average height of the irregularities on the surface of the substrate, and a portion protruding from the center line was defined as a convex portion B, and a portion recessed from the center line was defined as a concave portion A.

  Furthermore, the concave portion A having a shallow depth such that the maximum height difference of the unevenness on the surface of the substrate is 5 μm or less is difficult to appear on the resin film surface and hardly appears as a crater on the resin film surface. Therefore, if the base material 24 having a surface roughness with an elevation difference of 5 μm or less is used, the generation of craters can be suppressed accordingly.

Although not shown in FIG. 1, for example, a resin film of CO ₂ gas, O ₂ gas, He gas or the like toward the surface of the cooling roller 16 near the nip position M between the base material 24 and the resin film 12. It is preferable to provide a gas ejection nozzle that ejects a permeable gas. Gas that is permeable to the resin film 12 from the gas jet nozzle is blown toward the surface of the cooling roller 16 to form a gas curtain, and the accompanying air that flows toward the nip position M as the cooling roller 16 rotates. Is replaced with a permeable gas. As a result, in the area E surrounded by the resin film 12 and the cooling roller 16, it is difficult to form a dent in the resin film 12 as long as the gas is permeable even if gas is entrained on the surface of the resin film 12. Therefore, the generation of craters can be further effectively suppressed.

  Thus, the present invention can suppress the generation of craters and can produce a laminate 28 having an excellent surface appearance. In particular, even in a high speed region where the line speed exceeds 300 m / min, the generation of the number of craters can be effectively suppressed, so that productivity can be improved. Furthermore, since the crater can be significantly reduced, the thickness of the resin film 12 can also be reduced, thereby reducing raw material costs.

  Next, an example in which the laminate 28 is manufactured using the laminate manufacturing apparatus 10 of the present invention will be described.

  In the example, a laminate 28 was manufactured by laminating a resin film 12 (polyethylene) having a thickness of 25 μm on the surface of a strip-shaped substrate 24 (base paper) having a thickness of 175 μm and a width of 300 mm.

  Table 1 shows the relationship between the film thickness ratio [(B / A) × 100%] and the number of craters when the average period length indicating the surface roughness of the substrate 24 is constant at 100 μm. is there.

  Table 2 shows the relationship between the average periodic length of the substrate 24 and the number of craters when the film thickness ratio is kept constant at 85%. The line speed was high at 300 m / min. In addition, gas injection from the gas injection nozzle is not performed.

The “number of craters” in Tables 1 and 2 is the number per 1 cm ² of the resin film surface of the manufactured laminate 28.

表１の結果から分かるように、膜厚比率を小さくするに従って、クレータ数が減少する傾向にあり、試験２の膜厚比率９０％から試験３の膜厚比率８５％になったときにクレータ数が顕著に低減した。また、膜厚比率を小さくするに従って、クレータ数が減少する傾向にあるが、設備的な面から膜厚比率２０％が限界である。

As can be seen from the results in Table 1, the number of craters tends to decrease as the film thickness ratio is reduced, and the number of craters when the film thickness ratio of 90% in Test 2 becomes 85% in Test 3 Was significantly reduced. Moreover, although the number of craters tends to decrease as the film thickness ratio is reduced, the film thickness ratio of 20% is a limit from the viewpoint of equipment.

  In this way, the nip is performed so that the film thickness distribution is in the range of 20 to 85%, and the amount of the resin film 12 passing through the nip position M is reduced to reduce the generation of craters on the surface of the resin film. A laminate 28 having an excellent appearance could be produced. And although it changed and performed the kind of resin film, the same result can be obtained and it can apply irrespective of the kind of laminate to manufacture.

  As can be seen from the results in Table 2, tests 12 to 14 having an average period length of 50 μm or less, and tests 7 to 9 having a length of 100 μm or more have fewer craters than tests 9 to 11 of more than 50 μm and less than 100 μm. It was. From this, in addition to setting the film thickness ratio in Table 1 to 20 to 85%, the number of craters can be further reduced by setting the average periodic length of the substrate 24 to 50 μm or less, or 100 μm or more.

Overall configuration diagram of the laminate manufacturing apparatus of the present invention Explanatory drawing explaining an example of a structure of a 1st film thickness measurement means Explanatory drawing explaining the effect | action of this invention Explanatory drawing explaining the surface roughness of a base material

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus, 12 ... Resin film | membrane, 12A ... Reservoir part, 14 ... Extrusion die, 16 ... Cooling roller, 18 ... Nip roller, 20 ... Peeling roller, 22 ... Backup roller, 24 ... Base material, 30 ... Pressure adjusting device , 32 ... controller, 34 ... first film thickness measuring means, 36 ... second film thickness measuring means, 38 ... measuring device, 40 ... computer, 42, 44 ... disc, 46, 48 ... CCD camera, 50, 52 ... FFT analyzer, M ... Nip position

Claims (5)

A method for producing a laminate in which a base material and a resin film are nipped and bonded with a nip roller and a cooling roller while a surface of a traveling belt-like base material is coated with a resin film of a thermoplastic resin discharged in a molten state from a die In
Performing the nip so that the film thickness of the resin film of the laminate manufactured by the manufacturing method is in the range of 20 to 85% of the film thickness of the resin film at the nip position bonded to the base material, A method for producing a laminate, wherein the passage amount of the resin film passing through the nip position is reduced.   The average periodic length is 50 μm or less, or 100 μm or more, when the surface roughness of the substrate is represented by the average periodic length of irregularities present on the substrate surface. A method for producing a laminate.   The laminate according to claim 1 or 2, wherein when the surface roughness of the base material is expressed by the height difference of the unevenness existing on the surface of the base material, the maximum height difference is 5 µm or less. Method.   The method for producing a laminate according to any one of claims 1 to 3, wherein the laminate is a support for photographic paper. A manufacturing apparatus for a laminate in which a substrate and a resin film are nipped and bonded by a nip roller and a cooling roller while a surface of a traveling belt-like substrate is covered with a resin film of a thermoplastic resin discharged in a molten state from a die. In
First film thickness measuring means for measuring the film thickness of the resin film at the nip position to be bonded to the substrate;
Second film thickness measuring means for measuring the film thickness of the resin film of the laminate;
A controller for adjusting the nip pressure between the nip between the nip roller and the cooling roller based on the measurement results of the first and second film thickness measuring means and controlling the passage amount of the resin film passing through the nip position; A laminate manufacturing apparatus comprising:

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