WO2010035900A1 - Method for producing crystalline resin sheet - Google Patents

Abstract

A method for producing a crystalline resin sheet comprising a step for extruding crystalline resin in a sheet form from a die, a step for forming an extruded sheet by passing the extruded sheet-form crystalline resin through rolling rolls, and a step for conveying the extruded sheet in such a manner that the width direction of the surface of the extruded sheet is kept horizontal, characterized in that the step for conveying the extruded sheet is carried out by bringing the extruded sheet into contact with at least four conveyance rolls arranged in the conveyance direction of the extruded sheet, and includes a total of two or more steps including a step for bringing the upper surface of the extruded sheet into contact with the conveyance rolls in the conveyance direction and then bringing the lower surface of the extruded sheet into contact with the conveyance rolls in the conveyance direction, and/or a step for bringing the lower surface of the extruded sheet into contact with the conveyance rolls in the conveyance direction and then bringing the upper surface of the extruded sheet into contact with the conveyance rolls in the conveyance direction.

Description

Method for producing crystalline resin plate

The present invention relates to a method for producing a crystalline resin plate.

In recent years, high flatness has been required for a light diffusing plate used in a backlight device constituting a direct liquid crystal display. Conventionally, polymethylmethacrylate (PMMA) resin, methylmethacrylate-styrene copolymer (MS) resin, polystyrene (PS) resin, polycarbonate (PC) resin, etc. have been used as the light diffusion plate. It was a crystalline resin. On the other hand, light diffusing plates made of crystalline resins such as propylene resin are lightweight, have high mechanical strength and are not easily broken, and have the characteristics that they are not easily deformed by the effects of moisture absorption or heat from the light source. It is known (for example, JP 2008-083660 A (Patent Document 1)).
However, when a crystalline resin such as a propylene resin is molded by an extrusion molding method, heat generation due to crystallization is accompanied at the stage of cooling from the molten state and molding, so that it is difficult to control sheet warpage. In particular, as light diffusion plates used in backlight devices for liquid crystal displays, high flatness is required, so light diffusion plates made of crystalline resin such as propylene resin are manufactured while controlling warpage by extrusion molding. It was technically difficult to do.
As a method for preventing such warpage, conventionally, a method of passing on the transport roll in a flat state after passing the rolling roll at the time of extrusion molding (for example, see FIG. 5) has been adopted. Only concave warpage occurred in a cross section parallel to the direction), and no convex warpage in the MD direction occurred. Therefore, it has been difficult to suppress or control warpage. Since such a concave warp in the MD direction affects the warp of the obtained sheet, various methods for suppressing or eliminating the occurrence of the warp of the sheet including the concave warp in the MD direction have been studied.
For example, in Japanese Patent Laid-Open No. 2002-120248 (Patent Document 2), as shown in FIG. 6, the resin sheet 2 passing through the press rolls 3, 4, 5 is heated by the heaters 8, 9, and then the conventional method is used. Disclosed is a method for reducing distortion such as undulation. In addition, as shown in FIG. 7, JP 2002-120249 A (Patent Document 3) is provided with a warping roll 10 for adjusting the amount of warping, and the resin sheet 2 when passing through the warping roll 10. The method of controlling the temperature difference of the upper and lower surfaces of the resin sheet 2 at the time of conveyance by heating or cooling is disclosed. Japanese Patent Laid-Open No. 2005-088310 (Patent Document 4) discloses a method for suppressing the occurrence of warpage or adjusting the warpage by arranging a specific warping roll 20 as shown in FIG.

However, in the conventional method, the apparatus configuration for suppressing the warp is complicated, and the suppression or adjustment of the warp in the transport direction of the extruded sheet is insufficient, and the concave warp in the transport direction remains. was there. It is an object of the present invention to provide a method for producing a crystalline resin plate having excellent flatness by eliminating a warp of a sheet including such a concave warp and a simple method.
That is, the present invention includes a step of extruding a crystalline resin from a die into a sheet, a step of passing the extruded sheet-like crystalline resin through a rolling roll to form an extruded sheet, and a width of the sheet surface of the extruded sheet. A method of manufacturing a crystalline resin plate including a step of conveying an extruded sheet so that the direction is horizontal, and the step of conveying includes at least four conveying rolls arranged along the conveying direction of the extruded sheet. A step of bringing the upper surface of the extruded sheet into contact with the transport roll along the transport direction and then bringing the lower surface of the extruded sheet into contact with the transport roll along the transport direction. Crystallinity including at least one of the step of bringing the surface into contact with the transport roll along the transport direction and then bringing the upper surface of the extruded sheet into contact with the transport roll along the transport direction. The method of manufacturing a fat plate.
The transporting step is performed by contacting at least four transporting rolls arranged along the transporting direction of the extruded sheet, and this contact is performed on either the upper surface or the lower surface of the extruded sheet. It is preferable to alternately contact these along the transport direction.
The transporting step is performed when the crystallization temperature of the crystalline resin is T _c (° C.) and the first transporting roll is brought into contact with the first transporting roll along the transporting direction among four consecutively disposed transporting rolls. _Assuming that the temperature of the sheet surface on the side not in contact with the transport roll is T _warp (° C.), it is preferably performed under the condition that T _warp satisfies the following expression (1).
T _c −30 ≦ T _warp ≦ T _c +20 (1)
The production method of the present invention is suitable when the crystalline resin is a propylene resin.
According to the present invention, it is possible to suppress or control the concave warp in the conveyance direction by a simple method, and to reduce the warp of the entire sheet, compared to a sheet (resin plate) obtained by a conventional method, Generation | occurrence | production of the wave | undulation of a sheet | seat can be suppressed and the resin board excellent in flatness can be provided. Further, according to the method of the present invention, since the sheet is cooled at a shorter conveying distance than the conventional method, the sheet can be produced even in a small space where the conveying distance is more limited.

FIG. 1 is a schematic cross-sectional view of an apparatus used in the method for producing a crystalline resin plate of the present invention.
FIG. 2 is a schematic cross-sectional view showing the pitch of adjacent transport rolls.
FIG. 3 is a diagram illustrating a vertical positional relationship between adjacent transport rolls.
FIG. 4 is a schematic cross-sectional view of an apparatus used in the method for producing a crystalline resin plate in Example 1.
FIG. 5 is a schematic cross-sectional view of an apparatus used in a conventional method for producing a crystalline resin plate.
FIG. 6 is a schematic cross-sectional view of an apparatus used in a conventional method for producing a crystalline resin plate provided with a heater.
FIG. 7 is a schematic cross-sectional view of an apparatus used in a conventional method for producing a crystalline resin plate provided with a warping roll.
FIG. 8 is a schematic cross-sectional view of an apparatus used in a conventional method for producing a crystalline resin plate provided with three warping rolls.
FIG. 9 is a schematic cross-sectional view of an apparatus used in the method for producing a crystalline resin plate in Example 4.
FIG. 10: is a schematic sectional drawing which shows the 1st aspect of the positional relationship of (a) a conveyance roll and the extrusion sheet conveyed, (b) 2nd of the positional relationship of a conveyance roll and the extrusion sheet conveyed. It is a schematic sectional drawing which shows the aspect of (c) It is a schematic sectional drawing which shows the 3rd aspect of the positional relationship of a conveyance roll and the extrusion sheet conveyed, (d) The extrusion sheet conveyed with a conveyance roll, It is a schematic sectional drawing which shows the 4th aspect of this positional relationship.
FIG. 11 is a schematic cross-sectional view of an apparatus used in the method for producing a crystalline resin plate in Comparative Example 2.
FIG. 12 is a schematic diagram showing a cross-sectional shape of a replica of a V-shaped groove formed on the transfer mold.
FIG. 13 is a schematic diagram of a cross-sectional shape of a replica of a semicircular recess groove applied to a transfer mold.
FIG. 14 is a schematic diagram of a cylindrical lens.
FIG. 15 is a schematic diagram of an example of a cross-sectional shape of a replica of a recessed groove that is a V-shaped groove-curved surface combined shape applied to a transfer mold.
FIG. 16 is a schematic diagram of an example of a partial cross-sectional shape of a recessed groove having a V-shaped groove-curved surface combined shape.
FIG. 17 is a schematic diagram of another example of the cross-sectional shape of the replica of the recessed groove applied to the transfer mold.

Hereinafter, the present invention will be described in more detail. In the following description of the embodiments, the description is made with reference to the drawings. In the drawings of the present application, the same reference numerals denote the same or corresponding parts.
<Method for producing crystalline resin plate>
The method for producing a crystalline resin plate of the present invention comprises a step of extruding a crystalline resin from a die into a sheet, a step of passing the extruded sheet-like crystalline resin through a rolling roll to form an extruded sheet, And conveying the extruded sheet so that the width direction of the sheet surface of the sheet is horizontal.
In the present invention, a crystalline resin (hereinafter sometimes referred to simply as a resin) is a polymer compound having a property of becoming a crystal in a solid state, as defined in a chemical dictionary (Tokyo Kagaku Dojin) and the like. A resin (polymer) showing a crystalline diffraction peak in an X-ray diffraction spectrum. When a resin plate excellent in flatness is produced by extrusion molding in a crystalline resin, the occurrence of warpage of the entire sheet including concave warpage in the transport direction becomes a problem as described above. The present invention is effective for suppressing or eliminating warpage when such a crystalline resin is extruded to form a resin plate.
The crystalline resin may be composed of a single unit or may be composed of a copolymer containing two or more units. For example, a propylene polymer or a propylene copolymer containing 75% by mass or more of propylene units in the crystalline resin can be exemplified. Specifically, the propylene unit content is 75 to 100% by mass and the ethylene unit is 0%. It is preferably composed of a propylene polymer or a propylene copolymer containing 15 to 15% by mass and 1 to 25% by mass of 1-butene unit. More preferably, it is a case where it is composed of a propylene polymer containing 95% by mass or more of propylene units, 0 to 5% by mass of ethylene units and 0 to 5% by mass of 1-butene units, more preferably propylene units. This is a case where it is composed of 99% by mass or more, a propylene polymer containing 0 to 1% by mass of ethylene units and 0 to 1% by mass of 1-butene units. The propylene unit content may be 100% by mass. In addition, although the manufacturing method of this invention is especially useful for crystalline resin, also when using a thermoplastic resin or a thermosetting resin, it is possible to suppress the curvature of the whole sheet | seat.
In addition, additives such as a nucleating agent, a light diffusing agent, an ultraviolet absorber, a heat stabilizer, a processing stabilizer, and an antistatic agent may be added to the resin. The blending amount of these additives may be adjusted and used within a range that satisfies the effects of the present invention, and is not particularly limited. In addition, amorphous resins other than crystalline resins may be mixed to such an extent that the effects of the present invention are not impaired. In particular, when the resin constituting the extruded sheet is a propylene-based resin, mixing the acrylic resin causes the refractive indexes of these resins to be approximately equal, so that the mechanical properties such as rigidity are maintained without impairing the transparency of the resulting resin plate. This is useful as a method for improving the characteristics.
The light diffusing agent may be an inorganic light diffusing agent or an organic light diffusing agent. Examples of the inorganic light diffusing agent include particles of inorganic compounds such as calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, inorganic glass, talc, mica, white carbon, magnesium oxide, and zinc oxide. . The inorganic light diffusing agent may be surface-treated with a surface treatment agent such as a fatty acid. Examples of the organic light diffusing agent include organic compound particles such as styrene polymer particles, acrylic polymer particles, and siloxane polymer particles.
When a light diffusing agent is added, the absolute value of the difference between the refractive index of the added light diffusing agent and the refractive index of the resin is usually 0.02 or more in terms of the effect of light diffusion, and the resulting crystallinity In terms of light transmittance of the resin plate, it is usually 0.25 or less. Thus, when a light diffusing agent is added to resin, the obtained crystalline resin plate can be used as a light diffusing plate. The addition amount of the light diffusing agent is not particularly limited, and may be adjusted as appropriate.
When a nucleating agent is contained in the crystalline resin, the production efficiency of the sheet can be improved by promoting crystallization. As the nucleating agent, known ones such as organophosphate nucleating agents can be used. For example, the content may be 0.03 to 1.0 part by mass with respect to 100 parts by mass of the crystalline resin. However, it is not limited to this range.
The step of extruding the crystalline resin into a sheet is performed using a die. As such a die, a metal T die used in a conventionally known extrusion molding can be used. The resin is continuously extruded from the die in a heated and melted state, and an extruder can be used for this extrusion in the same manner as in a normal extrusion molding method. The extruder may be a single screw extruder or a twin screw extruder. The crystalline resin is heated in an extruder, sent to a die in a molten state, and extruded. The resin extruded from the die is continuously extruded in the form of a sheet. The shape of the sheet is not particularly limited, and the thickness and width are adjusted depending on the use of the obtained resin plate. Further, the extruded sheet may have a single layer structure or a laminated structure of two or more layers. What is necessary is just to change these structures suitably according to the use of the resin board obtained as mentioned above. For example, when used as a light diffusion plate, the total thickness is usually 0.1 mm to 3.0 mm, preferably 0.5 mm to 3.0 mm, and more preferably 0.8 mm to 3.0 mm.
The crystalline resin extruded into the sheet is then subjected to a step of forming an extruded sheet through a rolling roll. FIG. 1 shows a schematic cross-sectional view of an apparatus used in the method for producing a crystalline resin plate of the present invention. The crystalline resin sheet extruded from the die 1 is sandwiched between a first pressing roll and a second pressing roll, which are rolling rolls, and formed into a pressing sheet 2 having a desired thickness. The 1st press roll and the 2nd press roll which are rolling rolls should just be a well-known roll used for manufacture of such a resin board, and the diameter is not specifically limited, either. Further, the first, second and third pressing rolls may be mirror rolls or so-called transfer rolls having a lens shape, an embossed shape, a prism shape or the like. The surface temperature of these pressing rolls is not particularly limited, but it is usually preferable to set the temperature to 50 ° C to 150 ° C. When a pressed sheet is formed by rolling under such temperature conditions, the effect of improving the flatness of the resulting crystalline resin plate is further improved by combining with the subsequent steps of the method for producing the crystalline resin plate of the present invention. Can be made.
The transfer roll is a roll having a transfer mold on the surface. The transfer mold is pressed against the surface of the continuous resin sheet, and the surface shape is transferred to the continuous resin sheet as a reverse mold. The transfer mold is composed of, for example, a plurality of recesses or protrusions provided on the surface of the transfer roll, and the pitch interval between the recesses or protrusions is usually 10 μm or more, preferably 30 μm or more, because the transfer mold can be easily produced. Preferably it is 50 micrometers or more. The upper limit is not particularly limited, but is usually 500 μm or less, preferably 250 μm or less.
Further, the groove depth of the concave portion or the height of the top portion of the convex portion is 30 μm to 1500 μm from the viewpoint of manufacturing the transfer mold, but is not limited to this range.
The ratio of the groove depth to the pitch interval of the recesses of the transfer mold (groove depth / pitch interval) or the ratio of the top height to the pitch interval of the protrusions (top height / pitch interval) is the resin's crystallization temperature peak. When a crystalline polymer resin having a width of 9 ° C. or less is used, suitable transfer can be performed even if the ratio is 1 or more, and further 1.2 or more. The ratio of groove depth (groove depth / pitch interval) to the pitch interval of recesses of this transfer mold or the ratio of top height to the pitch interval of protrusions (top height / pitch interval) is usually 5 or less, preferably 3 or less. The ratio may be less than 1.
FIG. 12 is an example of a transfer mold surface, and is a cross-sectional surface view of a transfer mold having a V-shaped (triangle) cross-sectional shape. In FIG. 12, the top of the cross-sectional shape and the entire cross-sectional shape of the concave portion or the convex portion are V-shaped (triangles). As shown in FIG. 12, the transfer mold is provided with a plurality of concave portions or convex portions, and the pitch interval (P ′) between the concave portions or convex portions is the distance between the groove portions of adjacent concave portions (P in FIG. 12). ₁ ′) or the distance between the tops of adjacent convex portions (P ₂ ′ in FIG. 12), and the groove depth (H ′) of the concave portion means the vertical distance from the transfer roll surface to the deepest portion of the concave portion. The top height of the convex portion refers to the vertical distance from the bottom surface of the convex portion to the surface of the transfer roll, and is the same as the groove depth (H ′) of the concave portion in FIG.
When the top of the cross-sectional shape is V-shaped (triangle), the apex angle Θ ′ of the triangle can be 10 ° to 100 °. The apex angle Θ ′ may be in the range of 10 ° to 90 °. When a crystalline polymer resin having a crystallization temperature peak width of 9 ° C. or less is used as the resin, a fine transfer mold having a triangular apex angle Θ ′ of 10 ° to 60 ° is used. However, the transfer can be performed with high accuracy, and the surface shape of the obtained sheet is almost the same as that of the transfer mold.
The shape of the transfer mold is not limited to the one having a V-shaped cross section as shown in FIG. 12. For example, a substantially semicircular recess (substantially semicircular recess) having a substantially semicircular shape as shown in FIG. ) Or a groove in a recess having a V-shaped (triangular) apex angle Θ ′ and a curved side 12 ′ formed by a straight line 11 ′ having a V-shaped groove-curved surface as shown in FIG. Can be illustrated. In FIG. 13, the pitch interval (P ′) refers to the distance between the groove portions of adjacent recesses, as in FIG. 12, and the groove depth (H ′) of the recesses is perpendicular from the transfer roll surface to the deepest portion of the recesses. Say distance. Further, a substantially semicircular convex portion obtained by inverting a groove of a substantially semicircular concave portion is also included in the shape of the transfer mold. When the transfer mold is a substantially semicircular convex portion, the pitch interval refers to the distance between the top portions of adjacent convex portions, and the top height of the convex portion refers to the vertical distance from the bottom surface of the convex portion to the transfer roll surface. The substantially semicircular shape is not limited to a shape having a semicircular cross section as shown in FIG. 13, but a cylindrical body parallel to the axis thereof, such as a cylindrical lens shown in FIG. In addition, the shape may be any arc shape of a cross section when cut by a plane not including the axis, or the cross section is a semi-elliptical arc shape, a flat curved shape that is a part of the semi-elliptical arc shape, etc. The shape may also be The “substantially semicircular concave portion” or “substantially semicircular convex portion” includes such a concave portion or convex portion having a substantially semicircular cross section.
In FIG. 15, the pitch interval (P) means the distance between the groove portions of the adjacent concave portions or the distance between the top portions of the adjacent convex portions, as in FIG. 12, and the groove depth (H ′) of the concave portions is the transfer roll. The vertical distance from the surface to the deepest part of the recess. Further, the height of the top of the convex portion refers to a vertical distance from the bottom surface of the convex portion to the surface of the transfer roll, and is the same distance as the groove depth (H ′) of the concave portion. For example, as shown in FIG. 16, the V-shaped groove-curved surface combined shape has a slope formed by a V-shaped (triangular) apex angle Θ ′ and a curved side 12 ′ formed by a straight line 11 ′. If it is, it may have any shape of a cross section when cut by a plane not including the axis of the cylindrical body including the curved surface. The curved surface here may be a part of an arc shape, a part of an elliptical arc shape, or a shape formed of a curve other than an elliptical arc shape. The “V-groove-curved composite concave portion” includes such a concave portion having a substantially V-groove-curved composite cross section. Further, the shape of the concave portion or the convex portion does not include a straight line portion as shown in FIG. 15, but also includes a groove having a shape formed by intersecting curves 13 ′ as shown in FIG.
In addition, the concave portions or the convex portions in the transfer mold may be provided continuously as shown in FIG. 12, or may be provided in parallel with an arbitrary interval d as shown in FIGS. The interval between the concave portions or the interval between the convex portions is selected depending on the use of the obtained sheet. In the present invention, the pitch interval (P ′) and the groove depth (H ′) or the top height in the transfer mold are not necessarily constant in the entire transfer mold, but between the partially adjacent concave portions or convex portions. The case of different shapes is also included. In addition, the present invention includes a case where the V-shaped concave portion is inverted and the substantially semicircular convex portion is inverted. The interval d may be arbitrarily set depending on the use of the obtained sheet. However, when a crystalline polymer resin having a crystallization temperature peak width of 9 ° C. or less is used as the resin, the interval d ′ is 10 μm or less. Alternatively, even a fine transfer mold in which the interval d is not provided can be a method for producing a surface shape transfer resin sheet with good transfer rate and production efficiency.
As a method for producing the transfer mold, a known method can be adopted. For example, a plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating is performed on the surface of the transfer roll made of stainless steel, steel, or the like. Examples of methods for processing the shape by performing removal processing using a diamond tool, a metal grindstone, or the like, laser processing, or chemical etching on the plated surface after the coating is performed, are limited to these methods. Is not to be done.
Further, the surface of the transfer roll may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, etc. at a level that does not impair the accuracy of the surface shape after the transfer mold is formed.
After the step of forming the extruded sheet, the extruded sheet undergoes a step of transporting the sheet surface in a horizontal direction. Here, the extruded sheet may be conveyed to the first pressing roll and the second pressing roll in the horizontal direction and then conveyed by the conveying roll as it is. For example, as shown in FIG. It may include a step of being pressed by the third pressing roll 5 provided on the upper side, and then transported by the transporting roll 6. The addition of such steps may be adjusted by the crystallization temperature of the crystalline resin used as described later. In FIG. 1, the obtained pressing sheet 2 is conveyed by being moved upward from the die 1 by the first pressing roll 3 and the second pressing roll 4, but the second pressing roll 3 is below the first pressing roll 3. A form in which a third pressing roll is provided below the roll and the pressing sheet 2 is moved below the die 1 and then conveyed is also included in the manufacturing method of the present invention (see FIG. 9). In addition, the horizontal direction is sufficient if the width direction of the sheet surface is substantially parallel to the horizontal direction. For example, even if the width direction of the sheet surface is inclined within a range of ± 30 ° from the horizontal direction, The effect of the invention is achieved. Such a direction may be set within a range in which, for example, separation of the sheet from the conveyance roll due to inclination does not occur from the viewpoint of efficient conveyance of the sheet.
In the present invention, the transporting step is performed by contacting at least four transport rolls arranged along the transport direction of the extruded sheet, and the upper surface of the extruded sheet is brought into contact with the transport roll along the transport direction. After the process, the lower surface of the extruded sheet is brought into contact with the transport roll along the transport direction (hereinafter may be referred to as A process), and the lower surface of the extruded sheet is brought into contact with the transport roll along the transport direction. Thereafter, at least one step of bringing the upper surface of the extruded sheet into contact with the transport roll along the transport direction (hereinafter sometimes referred to as B step) is included in total. The step A and the step B may be included in a total of 2 or more, preferably 3 or more, and more preferably 4 or more. With the above configuration, since the sheet is cooled with a shorter conveying distance than in the conventional method, the sheet can be produced even in a small space where the conveying distance is more limited. Further, it is possible to suppress or control the concave warpage in the conveying direction and reduce the warpage of the entire sheet, and it is possible to manufacture a crystalline resin plate having excellent flatness as compared with the conventional method.
In each of the A process and the B process, there is one transport roll that contacts the lower surface of the extruded sheet and one transport roll that contacts the upper surface of the extruded sheet. Even when one or more rolls are provided, the effect of the present invention is exhibited as long as two or more of the A process and the B process are included and are in contact with at least four transport rolls.
That is, the process of performing at least one of the process A and the process B in combination of two or more is included, for example, continuously within 20 transport rolls continuous in the transport direction or via another transport roll. Preferably, it is included within 10 continuous transport rolls, and more preferably included within 6 continuous transport rolls. By including two or more of the A process and the B process in the range of the number of the transport rolls, the concave warp in the transport direction can be more efficiently suppressed or controlled.
FIGS. 10A to 10D are schematic cross-sectional views showing the positional relationship between the transport roll satisfying such a configuration and the extruded sheet to be transported. FIGS. 10 (a) to 10 (d) show an embodiment in which at least one of the A process and the B process is included in six transport rolls in total. 10 (a) and 10 (b), after the lower surface of the extruded sheet comes into contact with one transport roll, the upper surface of the extruded sheet is brought into contact with the lower surface of the extruded sheet into one transport roll. A step (B step) of contacting the upper surface of the extruded sheet with one conveying roll, and then a step of bringing the lower surface of the extruded sheet into contact with one conveying roll (A). Step), and then the step of bringing the upper surface of the extruded sheet into contact with one further conveying roll (FIG. 10A), or the step of bringing the lower surface of the extruded sheet into contact with one further conveying roll (see FIG. 10). b)). In FIG.10 (c), after making the lower surface of an extrusion sheet contact one conveyance roll, the process (B process) which makes the upper surface of an extrusion sheet contact one conveyance roll is repeated twice, And a step (A step) of bringing the lower surface of the extruded sheet into contact with one transport roll after the upper surface is brought into contact with one transport roll. Here, in the repetition of the B process, the part where the lower surface of the extruded sheet in the second half of the B process contacts is regarded as the first half of the A process, and the part where the upper surface of the extruded sheet in the first half of the second B process contacts the second half of the A process. In FIG. 10C, the process A and the process B are included four times in total, but each process is considered along the transport direction for convenience. In addition, the transport rolls are not considered redundantly between the processes. That is, in FIG.10 (c), A process is 1 time and B process is 2 times, and 3 processes are included in total. In FIG.10 (d), after making the lower surface of an extrusion sheet contact one conveyance roll, the process (B process) which makes the upper surface of an extrusion sheet contact one conveyance roll, and one conveyance roll A step of bringing the upper surface of the extruded sheet into contact with each other, a step of bringing the upper surface of the extruded sheet into contact with one conveying roll and then bringing the lower surface of the extruded sheet into contact with one conveying roll (step A), Furthermore, the process of making the lower surface of an extrusion sheet contact one conveyance roll is included.
In another preferred embodiment of the present invention, the transporting step is performed by contacting at least four transport rolls. These four rolls are arrange | positioned along the conveyance direction of an extrusion sheet | seat, and are arrange | positioned continuously. When the N-th transport roll and R _n from the conveying direction, it is possible to perform the step of transporting the device comprising four R ₁ ~ R ₄ as a transfer roll 1. The transport rolls may be brought into contact with the extruded sheet so as to satisfy the conditions described later, for example, when the four rolls arranged in this way are used. For example, when the four rolls R ₂ to R _{5 in} FIG. The effect is produced.
The upper limit of the number of the transport rolls is not particularly limited as long as it is at least four, but for example, the upper limit can be ten, and is generally up to about 300 in terms of the configuration on the apparatus. is there. However, even if the number of transport rolls exceeds this, the effect of the present invention is exhibited as long as the extruded sheet that contacts at least four of the transport rolls satisfies the conditions described later. Moreover, although the surface temperature of a conveyance roll does not need to be adjusted, the direction which can be adjusted to arbitrary temperature is preferable from the point of the ease of adjustment of curvature. Such adjustment of the surface temperature of the conveying roll may be performed by a temperature adjusting device provided in the conveying roll or a temperature adjusting device such as a heater provided above and below the conveying roll. In the case of heating the extruded sheet by adjusting the temperature in the transport roll, it is preferable because the heat resistance of the obtained crystalline resin plate is further improved.
Either the upper surface or the lower surface of the extruded sheet is in contact with each transport roll. In the present invention, the at least four transport rolls have an upper surface and a lower surface along the transport direction. It is preferable to make it the aspect which contacts alternately. Such contact will be specifically described with reference to FIG. When the extruded sheet 2 comes into contact with the four conveying rolls 6 of the conveying rolls R ₁ to R ₄ shown in FIG. 1, the lower surface of the extruded sheet 2 comes into contact with the _first conveying roll R ₁ along the conveying direction. Once transported Te for the first second transport roll R ₂ contacts the upper surface of the extruded sheet 2. Then, the third-th transport roll R ₃ is conveyed in contact with the lower surface of the extruded sheet 2, the fourth-th transport roll R ₄ is conveyed in contact with the upper surface of the extruded sheet 2. Further, when the first-th transporting roll R ₁ extruded upper surface of the sheet 2 to the contact, the second second transport roll R ₂ in contact a lower surface of the extruded sheet 2, a third conveying rolls R ₃ is in contact with the upper surface of the extruded sheet 2, and the lower surface of the extruded sheet 2 is in contact with the fourth transport roll R ₄ . In this way, even when the extruded sheet is conveyed so that the upper surface and the lower surface of the extruded sheet are alternately contacted along the conveying direction with respect to at least four conveying rolls, It becomes possible to suppress or eliminate the concave warp and the warp of the entire sheet. As a result, the planarity of the obtained crystalline resin plate can be improved.
As a method of making the contact between the extruded sheet and the transport roll in the case of including the A process and the B process as described above, and alternately contacting the upper surface and the lower surface of the extruded sheet with the transport roll, for example, for each transport roll This can be achieved by providing a known guide roll. Further, in each of at least four transport rolls, the surfaces of the extruded sheet are brought into contact with each other so that at least one of the step A and the step B is included in two or more, preferably each surface of the extruded sheet. As long as these are alternately brought into contact, for example, the contact surface of the fifth conveyance roll of the five conveyance rolls and the extruded sheet is not particularly limited, and the same applies even when more conveyance rolls are provided.
As the transport roll, a known transport roll can be used. The schematic sectional drawing which shows the pitch of the conveyance roll adjacent to FIG. 2 is shown. The diameter D of each conveyance roll can be set to a desired size, and may be set to a diameter D of 20 mm to 800 mm, for example. When indicating the center distance between the N-th transport roll _{R n} and the N + 1 th transport roll _{R n + 1} adjacent to each other in pitch P, the pitch P is preferably set to 30 mm ~ 2000 mm, be 100 mm ~ 800 mm Is more preferable. By setting it as such a pitch P, cooling of an extrusion sheet | seat and suppression of a concave curvature are performed more favorably. Pitch P of the transfer roll adjacent is not limited to certain ones, the N-th transport roll R _n and the N + 1 th transport roll R _{n + 1} between the pitch P and the N + 1 th transport roll R _{n + 1} and the N + 2-th of The pitch P with the transport roll R _{n + 2} may be different. Further, the ratio P / D between the pitch P and the diameter D of the transport rolls is preferably 0.6 to 10, and more preferably 1 to 6.
Although FIG. 1 illustrates a case where the transport rolls are provided at the same height in the vertical direction, the vertical heights of adjacent transport rolls are not necessarily the same. FIG. 3 shows a vertical positional relationship between adjacent conveyance rolls. When at least four transport rolls are set to R _m , R _{m + 1} , R _{m + 2} , and R _{m + 3 in} order along the transport direction, and the height position of the extruded sheet in the direction perpendicular to the extruded sheet is d _A , for example, the track in FIG. (a), the extruded sheet includes the case of placing the transport roll _{R m, R m + 1,} R m + 2 and _{R m + 3,} as is conveyed by the track to maintain a height of _{d a.} Further, for example, as shown in the trajectory (B) of FIG. 3, the transport rolls R _m and R _{m + 2} are arranged at positions where they are in contact with the lower surface of the extruded sheet at a height of d _A , and the transport rolls R _{m + 1} and R _{m + 3} are arranged. Also included is a mode in which the center of is positioned higher than R _m so that the center of the height becomes d _A. Further, as shown in the track (C) of FIG. 3, a mode in which all the transport rolls R _m to R _{m + 3} are arranged at the same position in the vertical direction is also included. As shown in the track (D) of FIG. 3, the center of the transport roll R _m and R _{m + 2} and is placed in contact with the lower surface of the extruded sheet at a height of d _A, transport rolls R _{m + 1} and R _{m + 3} There lower than d _a, i.e. may be aspects arranged from R _m to low. The tracks (A) to (D) are exemplary, and the position in the vertical direction is not limited to those shown in the drawing. For example, the tracks (A) to (D) can be combined to form, for example, a transport roll R _{m + 1.} Is arranged like the track (B), the transport rolls R _{m + 3} are arranged like the track (D), and the effect of the present invention is exerted even when the vertical positions are different from each other. Among these, when the at least four transport rolls are arranged so as to have a trajectory as shown in the trajectories (B) to (D) in FIG. 3, the moving distance of the pressing sheet between the transport rolls is, for example, It becomes longer than the case shown in the orbit (A), the pressure sheet is cooled, and the crystalline resin plate can be manufactured in a short time.
The transporting step is performed when the crystallization temperature of the crystalline resin is T _c (° C.) and the first transporting roll is brought into contact with the first transporting roll along the transporting direction among four consecutively disposed transporting rolls. _Assuming that the temperature of the sheet surface on the side not in contact with the transport roll is T _warp (° C.), it is preferable that the T _warp satisfy the following formula (1).
T _c −30 ≦ T _warp ≦ T _c +20 (1)
When the temperature T _warp (° C.) of the sheet surface satisfies the formula (1), the amount of warpage of the entire extruded sheet can be reduced. The temperature T _warp (° C.) of the sheet surface is preferably T _C −20 (° C.) or higher, and more preferably T _C +10 (° C.) or lower. In such a case, the warpage amount of the entire extruded sheet can be further reduced.
In the manufacturing method of this invention, you may provide the roll which is technically unrelated to this invention other than the said press roll and a conveyance roll. Such a roll is in contact with the extruded sheet, for example, a guide roll for conveying the extruded sheet so as to follow the first pressing roll and the second pressing roll, or the conveying roll, and the pressing sheet for the second pressing. The touch roll for making it closely_contact | adhere to a roll and a 3rd press roll can be mentioned. As such a guide roll or a touch roll, it is used for the said objective, Comprising: A conventionally well-known roll is applicable.
The crystalline resin plate produced by the method for producing a crystalline resin plate of the present invention has improved flatness as compared with a resin plate produced by a conventional method, and is therefore suitable for a backlight device. Used for.

　表１において、シート温度の符号ａ~ｋは押圧シートの温度測定を行なった箇所を示し、これらは図４に模式的に示されている。ａ~ｋそれぞれの箇所について、幅方向に異なる３点のシート温度を測定し、それら３点のシート温度を表１に記載した。なお符号ｆの測定においては、「ｆ上」とは搬送ロールＲ１と押圧シートの接触の際の搬送ロールに接触しない側の押圧シート２表面を示す。それ以外の符号ｅ~ｋにおいては、各搬送ロールに押圧シート２が接触する直前の押圧シートの上表面および下表面のそれぞれを「上」、「下」の表記で示す。ライン速度（ｍ／ｍｉｎ）はダイからの押出速度を示し、引取比率とは、第三押圧ロール５と搬送ロール６と図示しない引取ロールとでの押圧シートの引取割合の比を示し、本実施例および比較例では第三押圧ロール５／搬送ロール６／引取ロール＝１．０２５／０．９９８／０．９６０とした。
　表１のロール温度の欄の「第一」、「第二」、「第三」はそれぞれ第一押圧ロール、第二押圧ロール、第三押圧ロールを示す。反り量については、いずれも最大値を示しており、数値の前の「−」は反りがシート搬送の水平方向よりも凹んでいることを示し、「＋」は反りがシート搬送の水平方向よりも凸であったことを示す。

　表２の結果から明らかなように、本発明の方法により製造した結晶性樹脂板に対応するそれぞれの試験板の反り量は、従来の方法により得られた結晶性樹脂板に対応する試験板に比べて、いずれも反りが抑制された結果となった。また、その反り量の絶対値も、最大で５．９ｍｍ低減されることがわかる。
　（実施例４）
　［中間層材料マスターバッチ３の製造］
　プロピレン−エチレン共重合体（プロピレン単位含有量９９質量％以上、エチレン単位含有量１質量％未満、商品名「Ｅ１１１Ｇ」、プライムポリマー（株）製）を８５．０質量部と、ヒンダードアミン系光安定剤（商品名「キマソーブ１１９ＦＬ」、チバ・ジャパン（株）製）５．０質量部と、加工安定剤（商品名「スミライザーＧＰ」、住友化学（株）製）４．０質量部と、造核剤（商品名「ＨＰＮ−２０Ｅ」、ミリケン・ジャパン（株）製）６．０質量部とをドライブレンドした後、１８０℃~２６０℃で６５ｍｍ二軸押出機によりペレット化して、ペレット状の中間層材料マスターバッチ３を得た。
　［結晶性樹脂板の製造］
　本実施例４においては、図９に示すロール構成を備えた装置を用いた。ダイ１には、押出機が備えられており、後述の配合比で樹脂等を投入し、フィードブロックダイを経由させて単層状態で押出した。
　メイン押出機に、９５．０質量部のプロピレン−エチレン共重合体（プロピレン単位含有量９９質量％以上、エチレン単位含有量１質量％未満、商品名「Ｅ１１１Ｇ」、プライムポリマー（株）製）と、５．０質量部の上記中間層材料マスターバッチ３とをドライブレンドしたブレンド物を供給して、２００℃~２５０℃で溶融させた。メイン押出機における溶融混練は１２．６ｒｐｍで２８１ｋｇ／ｈの条件で行なった。
　上記溶融させたブレンド物を、フィードブロックダイを経由させてダイ温度２５０℃~２６５℃で押出しして、図９に示すロール構成を用いて、単層構造で、厚みが０．６ｍｍ、平均幅１１００ｍｍの結晶性樹脂板（Ｂ）を得た。得られた樹脂板の結晶化温度は１２５．０℃であった。
　［搬送ロール］
　搬送ロールは直径Ｄが６０ｍｍのものを合計６個用いた。隣接する搬送ロールの相対位置は、シート搬送方向に沿って数えた場合の第一番目の搬送ロール（図９中Ｒ_１）と押出シートとの接点の押出シートの垂直方向の高さと、該ロールに隣接するシート搬送方向に沿って数えた場合の第二番目の搬送ロール（図９中Ｒ_２）と押出シートとの接点との押出シートの垂直方向の高さとの差が６０ｍｍとなるように配置した（図３Ｃ参照）。すなわち、第一番目の搬送ロールＲ_１と第二番目の搬送ロールＲ_２との押出シートの垂直方向の高さはほぼ同じとなる。
　また、隣接する搬送ロールの間隔は、図９の搬送ロールＲ_１~Ｒ_６は、図２に示すピッチＰを３００ｍｍとし、搬送ロールの表面温度はそれぞれ調整せずに室温条件において結晶性樹脂板の製造を行なった。
　［搬送方法］
　搬送ロールＲ_６までは、図９に示すように押出シートが搬送ロールＲ_１の上側、搬送ロールＲ_２の下側、搬送ロールＲ_３およびＲ_４の上側、搬送ロールＲ_５およびＲ_６の下側に接触するように通過させ、搬送ロールＲ_７降は搬送ロールの上側にシートを通過させた。なお搬送ロールＲ_７以降のロールの直径は６０ｍｍとし、ピッチは３００ｍｍとし、搬送ロールＲ_７以降のロール表面の温度は調整しなかった。
　［押出シート表面温度：Ｔ_ｗａｒｐ］
　搬送方向に沿って数えた第一番目の搬送ロールＲ_１を通過する際の押出シートの表面温度であって、搬送ロールと接触しない側の押出シートの表面温度Ｔ_ｗａｒｐは１１１．６℃であった。
　得られた押出シートについて実施例１と同様に評価を行なった。結果を下記表３に示す。
　（比較例２）
　搬送方法を以下の条件に変更した以外は、実施例４と同様の方法により結晶性樹脂板を製造した。得られた結晶性樹脂板について、実施例１と同様に反り評価を行なった。結果を表３に示す。
　［搬送方法］
　全ての搬送ロールの上側にシートを通過させた（図１１）。搬送ロールの大きさやピッチ等は実施例４と同様とした。
　［押出シート表面温度：Ｔ_ｗａｒｐ］
　搬送方向に沿って数えた第一番目の搬送ロールＲ_１を通過する際の押出シートの表面温度であって、搬送ロールと接触しない側の押出シートの表面温度Ｔ_ｗａｒｐは１１２．０℃であった。

　このように、本発明の方法によれば、従来の装置の構成において、搬送方法を変更するだけで、著しく反りを抑制した平坦性に優れた結晶性樹脂板を製造できることが分かる。
　以上のように本発明の実施の形態および実施例について説明を行なったが、上述の各実施の形態および実施例の構成を適宜組み合わせることも当初から予定している。
　今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.
Example 1
[Manufacture of intermediate layer material master batch 1]
54.0 parts by mass of a propylene-ethylene copolymer (propylene unit content 99% by mass or more, ethylene unit content less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) as a light diffusing agent 40.0 parts by mass of styrene polymer particles (average particle size 0.8 μm, trade name “XX307K”, manufactured by Sekisui Plastics Co., Ltd.) and processing stabilizer (trade name “IRGAFOS168”, manufactured by Ciba Geigy) 2 0.0 parts by mass and 4.0 parts by mass of an antistatic agent (trade name “Electro Stripper TS-2B”, manufactured by Kao Corporation) were dry blended, and then 180 ° C. to 250 ° C. with a 65 mm twin screw extruder. Pelletization was performed to obtain a pellet-shaped intermediate layer material master batch 1.
[Manufacture of intermediate layer material master batch 2]
84.0 parts by mass of a propylene-ethylene copolymer (propylene unit content of 99% by mass or more, ethylene unit content of less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) and a processing stabilizer ( Product name “IRGAFOS168” (Ciba Geigy) 4.0 parts by mass, nucleating agent (organophosphate, product name “NA11”, ADEKA) 4.0 parts by mass, and antistatic agent (trade name) After dry blending 8.0 parts by weight of “Electro Stripper TS-2B” (manufactured by Kao Corporation), pelletization is performed by a 65 mm twin screw extruder at 180 ° C. to 250 ° C., and a pellet-shaped intermediate layer material master batch 2 was obtained.
[Manufacture of surface material master batch]
86.0 parts by mass of a propylene-ethylene copolymer (propylene unit content of 99% by mass or more, ethylene unit content of less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) and an ultraviolet absorber ( 5.0 parts by mass of benzotriazole, trade name “LA31”, manufactured by ADEKA), 5.0 parts by mass of light stabilizer (hindered amine, trade name “Tin855FF”, manufactured by Ciba Japan), and nucleating agent After dry blending 2.0 parts by weight (trade name “NA11”, manufactured by ADEKA) and 2.0 parts by weight of processing stabilizer (trade name “IRGAFOS168”, manufactured by Ciba Geigy) at 180 ° C. to 260 ° C. Pelletization was performed with a 65 mm twin screw extruder to obtain a pellet-shaped surface material masterbatch.
[Production of crystalline resin plate]
In the present Example 1, the apparatus provided with the roll structure shown in FIG. 4 was used. The die 1 is provided with a main extruder and a sub-extruder (not shown), and a resin or the like is introduced into each of these extruders at a compounding ratio described later, and laminated via a multi-manifold die. Co-extrusion in the state.
In the main extruder, 79.0 parts by mass of propylene-ethylene copolymer (propylene unit content of 99 mass% or more, ethylene unit content of less than 1 mass%, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) And 16.0 parts by mass of the intermediate layer material masterbatch 1 and 5.0 parts by mass of the intermediate layer material masterbatch 2 are fed and melted at 200 ° C. to 250 ° C. It was. Melt kneading in the main extruder was performed at 50.6 rpm under the condition of 759 kg / h.
In the sub-extruder, 90.0 parts by mass of propylene-ethylene copolymer (propylene unit content 99% by mass or more, ethylene unit content less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) Then, a blend obtained by dry blending 10.0 parts by mass of the surface material masterbatch was supplied and melted at 190 ° C to 250 ° C. Melting and kneading in the sub-extruder was performed at 41.5 rpm and 40.0 kg / h.
These melted blends are coextruded through a multi-manifold die at a die temperature of 250 ° C. to 260 ° C., and using the roll configuration shown in FIG. 4, a surface layer of 0.05 mm, an intermediate layer (light diffusion layer) ) A crystalline resin plate (A) having a three-layer structure of 1.1 mm and a surface layer of 0.05 mm, a total thickness of 1.2 mm, and an average width of 1400 mm was obtained. The crystallization temperature of the obtained resin plate was 125.1 ° C.
[Transport roll]
Ten transport rolls having a diameter D of 75 mm were used. The relative positions of the adjacent conveying rolls are the height in the vertical direction of the extruded sheet at the contact point between the _first conveying roll (R _{1 in} FIG. 4) and the extruded sheet when counted along the sheet conveying direction, and the roll. The difference between the height of the extruded sheet in the vertical direction between the contact point of the extruded sheet and the second conveying roll (R _{2 in} FIG. 4) when counted along the sheet conveying direction adjacent to the sheet is 75 mm. Arranged (see FIG. 3C). That is, the height of the first-th transporting roll R ₁ and the second vertical extruded sheet and the transport roll R ₂ is substantially the same.
Further, the intervals between the adjacent transport rolls are such that the transport rolls R ₁ to R ₅ in FIG. 4 have a pitch P shown in FIG. 2 of 250 mm and the transport rolls R ₅ to R _{10 have} a pitch P of 300 mm. The transport rolls R ₁ to R ₁₀ each had a surface temperature set to 90 ° C.
[Transport method]
Up to the transport roll R ₁₀ , the sheet surface of the extruded sheet is sequentially passed from the transport roll R ₁ so as to contact the transport roll, and after the transport roll R ₁₁ , the sheet is passed above the transport roll (FIG. 4). ). Note the diameter of the subsequent conveyor rolls _{R 11} rolls and 75 mm, the pitch as 300 mm, the vertical position of the rolls were the same as _{R 10.} The temperature of the transfer roll R ₁₁ subsequent roll surface was not adjusted.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the _first conveying roll R1 counted along the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 116.0 ° C. It was.
<Evaluation: Warpage measurement 1>
Three test plates each having a size of 400 mm × 400 mm were cut out at different points in the width direction of the crystalline resin plate (A) obtained in Example 1. The warpage was measured for each of these test plates. The warpage measurement is placed on a natural stone standing board (600 mm x 600 mm) made by Mitutoyo Corporation, and the amount (distance) floating from the standing board at each of the midpoints and the vertexes of the four sides of the test plate is a total of 8 points. It was measured. For each test plate, the amount of floating from the 16-plate total board on both sides was measured, and the maximum value among them was defined as the warpage amount (1). The measurement was performed at room temperature. The results for each test plate are shown in Tables 1 and 2.
<Evaluation: Warpage measurement 2>
Three test plates having a size of 400 mm × 400 mm were cut out at different points in the width direction of the obtained crystalline resin plate (A). Each of these test plates was subjected to visual warpage measurement. The warpage evaluation result by visual judgment is shown in Table 1 as “◯” when there is no waviness on the sheet and as “x” when there is waviness on the sheet.
(Example 2)
Using the intermediate layer material master batch 1, the intermediate layer material master batch 2, and the surface layer material master batch prepared in Example 1, a crystalline resin plate was manufactured by the following method.
[Production of crystalline resin plate]
In Example 2, an apparatus having the roll configuration shown in FIG. 4 was used. The die 1 is provided with a main extruder and a sub-extruder (not shown), and a resin or the like is introduced into each of these extruders at a compounding ratio described later, and laminated via a multi-manifold die. Co-extrusion in the state.
In the main extruder, 83.0 parts by mass of a propylene-ethylene copolymer (propylene unit content of 99 mass% or more, ethylene unit content of less than 1 mass%, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) 12.0 parts by mass of the intermediate layer material masterbatch 1 and 5.0 parts by mass of the intermediate layer material masterbatch 2 are supplied and melted at 200 ° C. to 250 ° C. It was. Melt kneading in the main extruder was performed at 43.6 rpm and 654 kg / h.
In the sub-extruder, 90.0 parts by mass of propylene-ethylene copolymer (propylene unit content 99% by mass or more, ethylene unit content less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) Then, a blend obtained by dry blending 10.0 parts by mass of the surface material masterbatch was supplied and melted at 190 ° C to 250 ° C. The melt-kneading in the sub-extruder was performed at 48.4 rpm and 46.7 kg / h.
These melted blends are coextruded through a multi-manifold die at a die temperature of 250 ° C. to 260 ° C., and using the roll configuration shown in FIG. 4, a surface layer of 0.05 mm, an intermediate layer (light diffusion layer) ) A crystalline resin plate (B) having a three-layer structure of 1.4 mm and a surface layer of 0.05 mm, a total thickness of 1.5 mm, and an average width of 1400 mm was obtained. The crystallization temperature of the obtained resin plate was 125.9 ° C. About the obtained crystalline resin board (B), the curvature evaluation similar to a crystalline resin board (A) was performed. The results are shown in Tables 1 and 2.
The conveyance roll, the arrangement method thereof, and the extrusion sheet conveyance method were performed in the same manner as in Example 1.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the _first conveying roll R1 counted along the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 119.9 ° C. It was.
(Example 3)
Using the intermediate layer material master batch 1, the intermediate layer material master batch 2, and the surface layer material master batch prepared in Example 1, a crystalline resin plate was manufactured by the following method.
[Production of crystalline resin plate]
In Example 3, an apparatus having the roll configuration shown in FIG. 4 was used. The die 1 is provided with a main extruder and a sub-extruder (not shown), and a resin or the like is introduced into each of these extruders at a compounding ratio described later, and laminated via a multi-manifold die. Co-extrusion in the state.
The main extruder has 95.0 parts by mass of a propylene-ethylene copolymer (propylene unit content of 99 mass% or more, ethylene unit content of less than 1 mass%, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) Then, a blend obtained by dry blending 5.0 parts by mass of the intermediate layer material master batch 2 was supplied and melted at 200 ° C. to 250 ° C. Melt kneading in the main extruder was performed at 36.7 rpm and 550 kg / h.
In the sub-extruder, 90.0 parts by mass of propylene-ethylene copolymer (propylene unit content 99% by mass or more, ethylene unit content less than 1% by mass, trade name “FSX20L8”, manufactured by Sumitomo Chemical Co., Ltd.) Then, a blend obtained by dry blending 10.0 parts by mass of the surface material masterbatch was supplied and melted at 190 ° C to 250 ° C. The melt-kneading in the sub-extruder was performed at 51.8 rpm under the condition of 50.0 kg / h.
These melted blends are coextruded through a multi-manifold die at a die temperature of 250 ° C. to 260 ° C., and using the roll configuration shown in FIG. 4, a surface layer of 0.05 mm, an intermediate layer (light diffusion layer) ) A crystalline resin plate (C) having a three-layer structure of 1.9 mm and a surface layer of 0.05 mm, a total thickness of 2.0 mm, and an average width of 1400 mm was obtained. The crystallization temperature of the obtained resin plate was 125.3 ° C. The obtained crystalline resin plate (C) was subjected to the same warp evaluation as the crystalline resin plate (A). The results are shown in Tables 1 and 2.
The conveyance roll, the arrangement method thereof, and the extrusion sheet conveyance method were performed in the same manner as in Example 1.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the first conveying roll R1 counted along the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 120.9 ° C. .
(Comparative Example 1)
A crystalline resin plate was produced by the same method as in Example 2 except that the conveying method was changed to the following conditions. The obtained crystalline resin plate was subjected to warpage evaluation in the same manner as in Example 1. The results are shown in Table 2.
[Conveying method]
The sheet was passed over all the transport rolls (FIG. 5). The size and pitch of the transport rolls were the same as in Example 2.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the _first conveying roll R1 counted along the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 121.0 ° C. It was.

In Table 1, reference numerals a to k of the sheet temperature indicate portions where the temperature of the pressing sheet was measured, and these are schematically shown in FIG. For each of the points a to k, three different sheet temperatures in the width direction were measured, and the three sheet temperatures are listed in Table 1. In the measurement of the symbol f, “on f” indicates the surface of the pressing sheet 2 on the side not in contact with the conveying roll when the conveying roll R1 is in contact with the pressing sheet. In other symbols ek, the upper and lower surfaces of the pressure sheet immediately before the pressure sheet 2 comes into contact with each transport roll are indicated by “upper” and “lower”, respectively. The line speed (m / min) indicates the extrusion speed from the die, and the take-off ratio indicates the ratio of the take-up ratio of the press sheet between the third press roll 5, the transport roll 6 and the take-off roll (not shown). In the examples and comparative examples, the third pressing roll 5 / the transporting roll 6 / the take-up roll = 1.025 / 0.998 / 0.960.
“First”, “second”, and “third” in the roll temperature column of Table 1 indicate a first pressing roll, a second pressing roll, and a third pressing roll, respectively. As for the amount of warpage, all show the maximum value, “−” in front of the numerical value indicates that the warpage is recessed from the horizontal direction of the sheet conveyance, and “+” indicates that the warpage is from the horizontal direction of the sheet conveyance. Is also convex.

As is apparent from the results in Table 2, the amount of warpage of each test plate corresponding to the crystalline resin plate produced by the method of the present invention is the same as that of the test plate corresponding to the crystalline resin plate obtained by the conventional method. In comparison, the warpage was suppressed in all cases. It can also be seen that the absolute value of the warpage amount is also reduced by 5.9 mm at the maximum.
Example 4
[Manufacture of intermediate layer material master batch 3]
85.0 parts by mass of a propylene-ethylene copolymer (propylene unit content 99% by mass or more, ethylene unit content less than 1% by mass, trade name “E111G”, manufactured by Prime Polymer Co., Ltd.), hindered amine light stability 5.0 parts by weight of an agent (trade name “Kimasorb 119FL”, manufactured by Ciba Japan Co., Ltd.), 4.0 parts by weight of a processing stabilizer (trade name “Sumilyzer GP”, manufactured by Sumitomo Chemical Co., Ltd.), After dry blending 6.0 parts by weight of a nucleating agent (trade name “HPN-20E”, manufactured by Milliken Japan Co., Ltd.), the mixture was pelletized by a 65 mm twin screw extruder at 180 ° C. to 260 ° C. Intermediate layer material master batch 3 was obtained.
[Production of crystalline resin plate]
In Example 4, an apparatus having the roll configuration shown in FIG. 9 was used. The die 1 was equipped with an extruder, and a resin or the like was charged at a blending ratio described later and extruded in a single layer state via a feed block die.
In the main extruder, 95.0 parts by mass of a propylene-ethylene copolymer (propylene unit content of 99% by mass or more, ethylene unit content of less than 1% by mass, trade name “E111G”, manufactured by Prime Polymer Co., Ltd.) A blend obtained by dry blending 5.0 parts by mass of the intermediate layer material master batch 3 was supplied and melted at 200 ° C. to 250 ° C. Melt kneading in the main extruder was performed at 12.6 rpm and 281 kg / h.
The melted blend is extruded through a feed block die at a die temperature of 250 ° C. to 265 ° C., and has a single layer structure with a thickness of 0.6 mm and an average width using the roll configuration shown in FIG. A 1100 mm crystalline resin plate (B) was obtained. The crystallization temperature of the obtained resin plate was 125.0 ° C.
[Transport roll]
A total of six transport rolls having a diameter D of 60 mm were used. The relative positions of the adjacent conveying rolls are the height in the vertical direction of the extruded sheet at the contact point between the _first conveying roll (R _{1 in} FIG. 9) and the extruded sheet when counted along the sheet conveying direction, and the roll. So that the difference between the height in the vertical direction of the extruded sheet at the contact point between the second conveyed roll (R _{2 in} FIG. 9) and the extruded sheet when counted along the sheet conveying direction adjacent to the sheet is 60 mm. Arranged (see FIG. 3C). That is, the height of the first-th transporting roll R ₁ and the second vertical extruded sheet and the transport roll R ₂ is substantially the same.
Further, the spacing between adjacent transport rolls is such that the transport rolls R ₁ to R ₆ in FIG. 9 have a pitch P shown in FIG. 2 of 300 mm, and the surface temperature of the transport rolls is not adjusted, and the crystalline resin plate at room temperature. Was manufactured.
[Conveying method]
Up to the transport roll R ₆ , as shown in FIG. 9, the extruded sheet is above the transport roll R ₁ , below the transport roll R ₂ , above the transport rolls R ₃ and R ₄ , below the transport rolls R ₅ and R ₆ . passed to contact a side, descending conveyor rolls R ₇ is passed through the sheet above the conveyor rolls. Note the diameter of the subsequent transport roll _{R 7} rolls and 60 mm, pitch was 300 mm, the temperature of the conveying roll _{R 7} and subsequent roll surface was not adjusted.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the _first conveying roll R1 counted in the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 111.6 ° C. It was.
The obtained extruded sheet was evaluated in the same manner as in Example 1. The results are shown in Table 3 below.
(Comparative Example 2)
A crystalline resin plate was produced by the same method as in Example 4 except that the conveying method was changed to the following conditions. The obtained crystalline resin plate was subjected to warpage evaluation in the same manner as in Example 1. The results are shown in Table 3.
[Conveying method]
The sheet was passed over all the transport rolls (FIG. 11). The size and pitch of the transport roll were the same as in Example 4.
[Extruded sheet surface temperature: T _warp ]
The surface temperature of the extruded sheet when passing through the _first conveying roll R1 counted along the conveying direction, and the surface temperature T _warp of the extruded sheet on the side not in contact with the conveying roll was 112.0 ° C. It was.

As described above, according to the method of the present invention, it is understood that a crystalline resin plate excellent in flatness with remarkably suppressed warpage can be manufactured only by changing the conveying method in the configuration of the conventional apparatus.
Although the embodiments and examples of the present invention have been described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Since the crystalline resin plate produced by the production method of the present invention is excellent in flatness, it is suitable for a light diffusing plate, that is, a backlight device constituting a direct liquid crystal display device.

1 die, 2 extruded sheet, 3 first press roll, 4 second press roll, 5 3rd press roll, 6 transport roll, 7 take-up roll, 8, 9 heater, 10, 20 warp roll.

Claims (4)

A step of extruding the crystalline resin from a die into a sheet, a step of passing the extruded sheet-like crystalline resin through a rolling roll to form an extruded sheet, and the width direction of the sheet surface of the extruded sheet is horizontal. A method for producing a crystalline resin plate comprising a step of conveying an extruded sheet as follows:
The step of conveying is performed in contact with at least four conveying rolls arranged along the conveying direction of the extruded sheet, and
A step of bringing the upper surface of the extruded sheet into contact with the conveying roll along the conveying direction and then bringing the lower surface of the extruded sheet into contact with the conveying roll along the conveying direction; A method for producing a crystalline resin plate, comprising at least one step of bringing the upper surface of the extruded sheet into contact with a transport roll along the transport direction after contacting the transport direction along the transport direction. The step of conveying is performed in contact with at least four conveying rolls arranged along the conveying direction of the extruded sheet, and
The method for producing a crystalline resin plate according to claim 1, wherein either the upper surface or the lower surface of the extruded sheet is alternately brought into contact with the respective transport rolls along the transport direction. In the transporting step, the crystallization temperature of the crystalline resin is T _c (° C.), and among the four continuously disposed transporting rolls, the first transporting roll is moved along the transporting direction. The crystallinity according to claim 1 or 2, wherein the temperature of the sheet surface on the side that does not come into contact with the conveying roll at the time of contact is T _warp (° C), and the T _warp is performed under a condition satisfying the following formula (1). Manufacturing method of resin plate.
T _c −30 ≦ T _warp ≦ T _c +20 (1) 4. The method for producing a crystalline resin plate according to claim 1, wherein the crystalline resin is a propylene resin.

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