SHAPING ROLL FOR MELT EXTRUSION MOLDING, SHAPING ROLL ASSEMBLY FOR MELT EXTRUSION MOLDING, AND MELT EXTRUSION MOLDING METHOD

Abstract

A shaping roll for melt extrusion molding used for melt extrusion molding of thermoplastic resin, the shaping roll for melt extrusion molding comprises a metal roll body, a first cylinder, and a second cylinder. The metal roll body has a heat medium passage internally. The first cylinder covers a surface of a middle portion of the roll body part. The second cylinder covers surfaces of both end portions of the roll body part. The first cylinder comprises a first metal material having a thermal conductivity of 40 W/m.Math.K or more. The second cylinder comprises a second metal material having a thermal conductivity of 20 W/m.Math.K or less. The first cylinder and the second cylinder are at least partially joined to each other.

Claims

1. A shaping roll for melt extrusion molding used for melt extrusion molding of thermoplastic resin, the shaping roll for melt extrusion molding comprising: a metal roll body having a heat medium passage internally; a first cylinder covering a surface of a middle portion of the roll body part; a second cylinder covering surfaces of both end portions of the roll body part; the first cylinder comprising a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the second cylinder comprising a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the first cylinder and the second cylinder are at least partially joined to each other.

2. The shaping roll for melt extrusion molding according to claim 1, wherein the second cylinder covers the surfaces of the both end portions of the roll body part with an extension part of the first cylinder.

3. The shaping roll for melt extrusion molding according to claim 1, wherein an extension part of the first cylinder covers a surface of the second cylinder.

4. The shaping roll for melt extrusion molding according to claim 1, wherein a plating layer is formed on at least a surface of the first cylinder.

5. The shaping roll for melt extrusion molding according to claim 4, wherein the plating layer is selected from a group including a copper plating layer, a nickel plating layer, an electroless nickel-phosphorus plating layer, an electrolytic nickel-phosphorus plating layer, and a chrome plating layer.

6. The shaping roll for melt extrusion molding according to claim 4, wherein a surface of the plating layer comprises a mat pattern, a prism pattern, or a micro lens array pattern.

7. The shaping roll for melt extrusion molding according to claim 1, wherein the first metal material comprises carbon steel, chrome steel, or chrome molybdenum steel.

8. The shaping roll for melt extrusion molding according to claim 1, wherein the second metal material comprises nickel steel or stainless steel.

9. The shaping roll for melt extrusion molding according to claim 1, wherein the roll body part comprises the first metal material.

10. A shaping roll for melt extrusion molding used for melt extrusion molding of thermoplastic resin, the shaping roll for melt extrusion molding comprising: a roll body part having a heat medium passage internally and cutouts on outer surfaces of both end portions; and a cylindrical member fitted into the cutouts in the both end portions of the roll body part; the roll body part comprising a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the cylindrical member comprising a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the cylindrical member being at least partially joined to the cutouts of the roll body part.

11. The shaping roll for melt extrusion molding according to claim 10, wherein a plating layer is formed on surfaces of the roll body part and the cylindrical members.

12. The shaping roll for melt extrusion molding according to claim 11, wherein the plating layer is selected from a group including a copper plating layer, a nickel plating layer, an electroless nickel-phosphorus plating layer, an electrolytic nickel-phosphorus plating layer, and a chrome plating layer.

13. The shaping roll for melt extrusion molding according to claim 11, wherein a surface of the plating layer comprises a mat pattern, a prism pattern, or a micro lens array pattern.

14. The shaping roll for melt extrusion molding according to claim 10, wherein the first metal material comprises carbon steel, chrome steel, or chrome molybdenum steel.

15. The shaping roll for melt extrusion molding according to claim 10, wherein the second metal material comprises nickel steel or stainless steel.

16. A shaping roll assembly for melt extrusion molding comprising: a shaping roll for melt extrusion molding; a pressure roll disposed facing the shaping roll for melt extrusion molding; the shaping roll for melt extrusion molding comprising a metal roll body having a heat medium passage internally; a first cylinder covering a surface of a middle portion of the roll body part; a second cylinder covering surfaces of both end portions of the roll body part; the first cylinder comprising a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the second cylinder comprising a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the first cylinder and the second cylinder being at least partially joined to each other.

17. A shaping roll assembly for melt extrusion molding comprising: a shaping roll for melt extrusion molding; a pressure roll disposed facing the shaping roll for melt extrusion molding; the shaping roll for melt extrusion molding comprising a roll body part having a heat medium passage internally and cutouts on outer surfaces of both end portions; a cylindrical member fitted into the cutouts in the both end portions of the roll body part; the roll body part comprising a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the cylindrical member comprising a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the cylindrical member being at least partially joined to the cutouts of the roll body part.

18. A melt extrusion molding method using a shaping roll assembly for melt extrusion molding comprising a shaping roll for melt extrusion molding and a pressure roll disposed facing the shaping roll for melt extrusion molding, comprising steps of: pushing molten thermoplastic resin out from a die; passing molten thermoplastic resin through a gap between the shaping roll for melt extrusion molding and the pressure roll to obtain a sheet molded article; the shaping roll for melt extrusion molding comprising: a metal roll body having a heat medium passage internally; a first cylinder covering a surface of a middle portion of the roll body part; a second cylinder covering surfaces of both end portions of the roll body part; the first cylinder comprises a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the second cylinder comprises a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the first cylinder and the second cylinder are at least partially joined to each other.

19. A melt extrusion molding method using a shaping roll assembly for melt extrusion molding including a shaping roll for melt extrusion molding and a pressure roll disposed facing the shaping roll for melt extrusion molding, comprising steps of: pushing molten thermoplastic resin out from a die; passing molten thermoplastic resin through a gap between the shaping roll for melt extrusion molding and the pressure roll to obtain a sheet molded article; the shaping roll for melt extrusion molding comprising: a roll body part having a heat medium passage internally and cutouts on outer surfaces of both end portions; a cylindrical member fitted into the cutouts in the both end portions of the roll body part; the roll body part comprising a first metal material having a thermal conductivity of 40 W/m.Math.K or more; the cylindrical member comprising a second metal material having a thermal conductivity of 20 W/m.Math.K or less; and the cylindrical member being at least partially joined to the cutouts of the roll body part.

20. The melt extrusion molding method according to claim 18, wherein the obtained sheet molded article has a thickness from 0.05 mm to 0.5 mm.

21. The melt extrusion molding method according to claim 18, wherein the thermoplastic resin is selected from a group including polycarbonate resin, acrylic resin, polystyrene resin, thermoplastic polyester resin, annular polyolefin resin, and polymethyl-1-pentene resin.

22. The melt extrusion molding method according to claim 18, wherein the obtained sheet molded article comprises a light diffusion film or a brightness enhancement sheet.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] FIG. 1A is a cross sectional view schematically illustrating a shaping roll for melt extrusion molding according to embodiment 1

[0049] FIG. 1B is a conceptual view illustrating the disposition of a die and a shaping roll assembly for melt extrusion molding according to embodiment 1.

[0050] FIG. 2 is a cross sectional view schematically illustrating a shaping roll for melt extrusion molding according to embodiment 2.

[0051] FIG. 3A is a cross sectional view schematically illustrating a shaping roll for melt extrusion molding according to embodiment 3

[0052] FIG. 3B is a cross sectional view schematically illustrating a modification of the shaping roll for melt extrusion molding according to embodiment 3.

[0053] FIG. 4A is a cross sectional view schematically illustrating a shaping roll for melt extrusion molding according to embodiment 4

[0054] FIG. 4B is a cross sectional view schematically illustrating a roll body part according to embodiment 4.

[0055] FIG. 5 is a graph indicating the result of measurement of haze values of sheet molded articles molded using the shaping roll for melt extrusion molding according to embodiment 1 and a shaping roll for melt extrusion molding according to comparative example 1.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0056] The invention will be described below based on embodiments with reference to the drawings. However, the invention is not limited to the embodiments and values and materials in the embodiments are only examples.

Embodiment 1

[0057] Embodiment 1 relates to the shaping roll for melt extrusion molding, the shaping roll assembly for melt extrusion molding, and the melt extrusion molding method according to the first aspect of the invention. FIG. 1A is a cross sectional view schematically illustrating a shaping roll 1A (first roll) for melt extrusion molding according to embodiment 1 taken along a virtual plane including an axial line and FIG. 1B is a conceptual view illustrating the disposition of a die and a shaping roll assembly for melt extrusion molding according to embodiment 1.

[0058] The first roll 1A according to embodiment 1 is a shaping roll for melt extrusion molding used for melt extrusion molding of thermoplastic resin and comprises

[0059] a metal roll body 10 having a heat medium passage 11 internally,

[0060] a first cylinder 12 covering a surface of a middle portion of the roll body part 10, and

[0061] second cylinders 13 covering surfaces of both end portions of the roll body part 10. The first cylinder 12 comprises a first metal material having a thermal conductivity of 40 W/m.Math.K or more and the second cylinders 13 comprise a second metal material having a thermal conductivity of 20 W/m.Math.K or less, and the first cylinder 12 and the second cylinders 13 are at least partially joined to each other. The first metal material of the first cylinder 12 and the second metal material of the second cylinders 13 are specifically indicated in Table 2 below.

[0062] As illustrated in FIG. 1B, the shaping roll assembly for melt extrusion molding according to embodiment 1 comprises the first roll 1A according to embodiment 1 described above and a second pressure roll 2 disposed facing the first roll 1A. In embodiment 1, the second roll 2 comprises a rubber roll made of fluororesin.

[0063] The first cylinder 12 and the second cylinders 13 are shrink-fitted to the roll body part 10. The value of the inner diameter D.sub.2-i of the first cylinder 12 and the second cylinders 13 at normal temperatures and the value of the outer diameter D.sub.1-o of the roll body part 10 at normal temperatures are indicated in Table 2 below. That is, the shrink-fitting margin is assumed to be 0.1 mm. In addition, the wall thickness of the first cylinder 12 and the second cylinders 13 is assumed to be 7.00 mm. In embodiment 1, the roll body part 10 is assumed to be a so-called drilled roll having the heat medium passage 11 formed into a circular pipe by a cutting drill so as to extend from the side of the roll body part 10 in parallel with the axial direction. The number of heat medium passages 11 is essentially arbitrary. Thermal oil is used as the heat medium of the roll body part 10. Although the linear expansion coefficients of the first metal material and the second metal material of the first cylinder 12 and the second cylinders 13 are slightly larger than the linear expansion coefficient of the metal material of the roll body part 10, it is possible to prevent the first cylinder 12 and the second cylinders 13 from being loosened by making the shrink-fitting margin slightly larger. In some cases, the end parts of the second cylinders 13 may be spot-welded to the roll body part 10 to prevent them from rotating idle or being removed.

[0064] Plating layers 14 (specifically, 0.1-mm-thick electrolytic nickel plating layers) are formed on the surfaces of the first cylinder 12 and the second cylinders 13 having the surface roughness polished to approximately 0.7S. Buffing is applied to the surface of the plating layer 14 and then fine convexo-concave shapes are formed on the surface using a sand blasting method. Formation of the plating layers 14 and the optical pattern on the surfaces of the first cylinder 12 and the second cylinders 13 was performed after attachment of the first cylinder 12 and the second cylinders 13 to the roll body part 10. The transparent replicas of the surfaces (plating layers 14) of the first cylinder 12 and the second cylinders 13 were manufactured using UV-curable resin GLX18-73N (refraction index of 1.49) manufactured by Gluelabo Ltd. and the haze value (turbidity) was measured. As a result, the haze values were 86% and 85% and the surface roughness of the first cylinder 12 was substantially the same as the surface roughness of the second cylinders 13.

[0065] When the width of the sheet molded article formed by melt extrusion molding using the shaping roll for melt extrusion molding is W.sub.0 and the length of the first cylinder 12 is X.sub.1, the following expression is met.

W.sub.0>X.sub.1

Alternatively, the following expression is met.

30 mmW.sub.0X.sub.1300 mm

When the length of the second cylinders 13 is X.sub.2, the following expression is met.

30 mmX.sub.2300 mm

In addition, when the length of the second cylinders 13 is X.sub.2, the following expression is met.

(X.sub.1+2.Math.X.sub.2)>W.sub.0+30 (mm)

The values of X.sub.1 and X.sub.2 and the value of W.sub.0 are specifically indicated in Table 2 below. The total length (X.sub.1+2.Math.X.sub.2) of the first cylinder 12 and the second cylinders 13 is the same as the face length of the roll body part 10. The state in which the region of X.sub.2 overlaps the end part of the sheet molded article by 30 mm or more is preferable.

TABLE-US-00002 TABLE 2 Metal material of the roll body part S45C Thermal conductivity 45 W/m .Math. K Linear expansion coefficient 12 10.sup.6 mm/mm .Math. K First metal material S25C Thermal conductivity 50 W/m .Math. K Linear expansion coefficient 12 10.sup.6 mm/mm .Math. K Second metal material SUS309 Thermal conductivity 14 W/m .Math. K Linear expansion coefficient 15 10.sup.6 mm/mm .Math. K D.sub.1-o 386.0 mm D.sub.2-I 385.8 mm D.sub.2-o 400.0 mm X.sub.1 300 mm X.sub.2 195 mm W.sub.0 450 mm

[0066] In embodiment 1, polycarbonate resin (polycarbonate resin lupilon H3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the thermoplastic resin. In addition, the nominal thickness of the sheet molded article (film molded article) obtained by the melt extrusion molding method in embodiment 1 is 130 m and the width W.sub.0 is indicated in Table 2. The obtained sheet molded article (film molded article) is a light diffusion sheet (light diffusion film) and a mat pattern is formed thereon.

[0067] In embodiment 1, a well-known melt extrusion molding apparatus is used to pass molten thermoplastic resin pushed out of the die through the gap between the first roll 1A and the second roll 2 and apply a pressure to the sheet type molten thermoplastic resin to obtain the sheet molded article (film molded article). The molding conditions are indicated in Table 3 below.

TABLE-US-00003 TABLE 3 Die temperature 270 C. Line speed 7 m/min First roll temperature 140 C. Second roll temperature 70 C. Line pressure level 6 kg/cm

[0068] A first roll was manufactured as comparative example 1 in the same way as in embodiment 1 except the use of cylindrical members made of S45C (having the same dimensions as the cylindrical members obtained by integrating the first cylinder 12 and the second cylinders 13 according to embodiment 1). The transparent replicas of the surfaces (plating layers) of the cylindrical members were manufactured using UV-curable resin GLX18-73N and the haze value was measured. As a result, the haze value was 86%, which indicates substantially the same surface shape as in embodiment 1. A sheet molded article (film molded article) was molded under conditions substantially the same as in embodiment 1.

[0069] FIG. 5 indicates the measurement results of the haze values of sheet molded articles that have been molded using the first roll according to embodiment 1 and the first roll according to comparative example 1. In FIG. 5, A indicates the measurement result using the first roll according to embodiment 1 and B indicates the measurement result using the first roll according to comparative example 1. In embodiment 1, in the sheet molded article (film molded article) that has been molded, there is no appearance failure such as a peeling mark caused by failure of separation from the first cylinder 12 and the haze values were 71% to 72% in the middle part and 70% to 72% in the end part, so a difference in the haze values was hardly observed between the middle part and the end part. In contrast, in comparative example 1, there is no appearance failure such as a peeling mark caused by failure of separation from the cylindrical members in the sheet molded article (film molded article) that has been molded, but the haze values were 71% to 72% in the middle part and 67% to 70% in the end part, so a difference (approximately 3%) in the haze values was observed between the middle part and the end part.

[0070] As described above, in embodiment 1, the first roll 1A comprises the roll body part 10, the first cylinder 12, and the second cylinders 13 and the thermal conductivity of the first metal material of the first cylinder 12 and the thermal conductivity of the second metal material of the second cylinders 12 are defined. Accordingly, the cooling speed appropriate for manufacturing the sheet molded article of thermoplastic resin can be obtained. In addition, since the second cylinders 13 are made of the second metal material having a low thermal conductivity, the cooling of the molten thermoplastic resin (sheet) immediately after contact with the second cylinders 13 is delayed and the time required to transfer an optical pattern and the like can be obtained and the transfer rate of an optical pattern and the like can be improved. In addition, since the roll body part 10 is made of the first metal material and the sheet molded article immediately before separation from the second cylinders 13 is sufficiently cooled, the generation of peeling marks can be prevented effectively. As a result, the sheet molded article (film molded article) having no difference in the haze values between the middle part and the end part could be obtained.

Embodiment 2

[0071] Embodiment 2 is a modification of embodiment 1. FIG. 2 is a cross sectional view schematically illustrating a shaping roll (first roll) 1B for melt extrusion molding according to embodiment 2 when the first roll is taken along a virtual plane including the axial line.

[0072] In embodiment 2, a roll body part 20 is also referred to as a spiral roll and a heat medium passage 21 is a spiral double-pipe roll. The specifications of the roll body part 20, a first cylinder 22, and second cylinders 23 of the first roll 1B according to embodiment 2 are indicated in Table 2. As in embodiment 1, the first cylinder 22 and the second cylinders 23 are shrink-fitted to the roll body part 20 and the shrink-fitting margin and the wall thickness of the first cylinder 22 and the second cylinders 23 are the same as in embodiment 1. In the heat medium passage 21, there is a continuous dividing wall (partitioning wall) 25 extending spirally along the axial line of the roll body part 20. The number of dividing walls 25 is essentially arbitrary. Heat medium oil was used as the heat medium of the roll body part 20.

[0073] In addition, an approximately 0.3-mm-thick electrolytic nickel-phosphorus plating layer 24 was formed on the surfaces of the first cylinder 22 and the second cylinders 23 and a prism pattern having a nominal pitch of 100 m, a nominal height of 50 m, and a nominal angle of 90 degrees was provided by cut machining using a diamond cutting tool. Unlike embodiment 1, a metal elastic roll covered with hard chrome plating was used as the second roll 2.

[0074] In embodiment 2, polycarbonate resin lupilon H3000 was used as in embodiment 1. In addition, the nominal thickness of a sheet molded article (film molded article) obtained by a melt extrusion molding method according to embodiment 2 is 300 m. The obtained sheet molded article (film molded article) is a brightness improvement sheet (brightness improvement film) and a prism pattern is formed thereon.

[0075] Also in embodiment 2, a well-known melt extrusion molding apparatus is used to pass molten thermoplastic resin pushed out of the die through the gap between the first roll 1B and the second roll 2 and apply a pressure to the sheet type molten thermoplastic resin to obtain the sheet molded article (film molded article). The molding conditions are indicated in Table 4 below.

TABLE-US-00004 TABLE 4 Die temperature 280 C. Line speed 5 m/min First roll temperature 135 C. Second roll temperature 120 C. Line pressure level 10 kg/cm

[0076] The appearance of the prism film having been molded was good. Specifically, the average transfer rate in the middle part of the sheet molded article (film molded article) having been molded was 85% and the average transfer rate in the end part was 84%, so a difference in the average transfer rate was hardly observed between the middle part and the end part. In addition, since the thick portion at the edge of the sheet molded article was easily pressed, the transfer rate was relatively improved.

[0077] The first roll was manufactured as comparative example 2 in the same way as in embodiment 2 except the use of cylindrical members made of S45C (having the same dimensions as the cylindrical members obtained by integrating the first cylinder 22 and the second cylinders 23 according to embodiment 2). Then, a sheet molded article (film molded article) was manufactured under the same conditions as in embodiment 2. The average transfer rate in the middle part of the sheet molded article (film molded article) having been molded was 83% and the average transfer rate in the end part was 80%, so the transfer rates are relatively low and a difference in the average transfer rate was observed between the middle part and the end part.

Embodiment 3

[0078] Embodiment 3 is a modification of embodiment 1 or embodiment 2. FIG. 3A or FIG. 3B illustrates a cross sectional view schematically illustrating a shaping roll (first roll) for melt extrusion molding. A first roll 1C illustrated in FIG. 3A and FIG. 3B is a modification of the first roll according to embodiment 1. In embodiment 3, the second cylinders 13 cover the surfaces of both end portions of the roll body part 10 with extension parts 12A of the first cylinder. The extension parts 12A of the first cylinder are in contact with the roll body part 10 and the second cylinders 13 are disposed on the extension parts 12A of the first cylinder. Specifically, threads (not illustrated) are formed on the internal surfaces of the second cylinders 13 and the outer surfaces of the extension parts 12A of the first cylinder, so that the second cylinders 13 and the extension parts 12A of the first cylinder are integrally screwed with each other. However, the integration of the second cylinders 13 and the extension parts 12A of the first cylinder is not limited to such a method. The second cylinders 13 may be integrally shrink-fitted to the extension parts 12A of the first cylinder or the second cylinders 13 may be integrally welded to the extension parts 12A of the first cylinder.

[0079] Molding was performed using the first roll 1C according to embodiment 3 illustrated in FIG. 3A. The specifications of the first roll 1C and the like are indicated in Table 5. The roll body part 10 is made of the first metal material as in the first cylinder 12. Also in embodiment 3, as in embodiment 2, an approximately 0.3-mm-thick electroless nickel-phosphorus plating layer 14 was formed on the surfaces of the first cylinder 12 and second cylinders 13, a prism pattern having a nominal pitch of 100 m, a nominal height of 50 m, and a nominal angle of 90 degrees was provided in a 700-mm-long part of the first roll 1C by cut machining using a diamond cutting tool. Unlike embodiment 1, a metal elastic roll covered with hard chrome plating was used as the second roll 2 as in embodiment 2.

TABLE-US-00005 TABLE 5 Metal material of the roll body part SCM440 Thermal conductivity 43 W/m .Math. K Linear expansion coefficient 12 10.sup.6 mm/mm .Math. K First metal material SCM440 Second metal material SUS309 Thermal conductivity 14 W/m .Math. K Linear expansion coefficient 15 10.sup.6 mm/mm .Math. K D.sub.1-o 270.0 mm D.sub.2-I 269.8 mm D.sub.2-o 300 mm Wall thickness of the extension parts of the first 7.5 mm cylinder Wall thickness of the second cylinders 7.5 mm X.sub.1 580 mm X.sub.2 160 mm W.sub.0 680 mm

[0080] In embodiment 3, polycarbonate resin (polycarbonate resin lupilon S3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the thermoplastic resin. In addition, the nominal thickness of a sheet molded article (film molded article) obtained by a melt extrusion molding method in embodiment 3 is 300 m. The obtained sheet molded article (film molded article) is a brightness improvement sheet (brightness improvement film) and a prism pattern is formed thereon.

[0081] In embodiment 3, a well-known melt extrusion molding apparatus is used to pass molten thermoplastic resin pushed out of an 800-mm-wide die through the gap between the first roll 1C and the second roll 2 and apply a pressure to the sheet type molten thermoplastic resin to obtain the sheet molded article (film molded article). The molding conditions are indicated in Table 6 below.

TABLE-US-00006 TABLE 6 Die temperature 290 C. Line speed 5 m/min First roll temperature 135 C. Second roll temperature 120 C. Line pressure level 20 kg/cm

[0082] The first roll was manufactured as comparative example 3 in the same way as in embodiment 3 except the use of cylindrical members made of SCM440 (having the same dimensions as the cylindrical members obtained by integrating the first cylinder 12 and the second cylinders 13 according to embodiment 3). A sheet molded article (film molded article) was molded under conditions substantially the same as in embodiment 3.

[0083] Also in embodiment 3, a well-known melt extrusion molding apparatus is used to pass molten thermoplastic resin pushed out of the die through the gap between the first roll 1C and the second roll 2 and apply a pressure to the sheet type molten thermoplastic resin to obtain a sheet molded article (film molded article). The appearance of the prism film having been molded was good. Specifically, the average transfer rate in the middle part of the sheet molded article (film molded article) having been molded was 75% and the average transfer rate in the end part was 76%, so a difference in the average transfer rate is hardly observed between the middle part and the end part. In addition, since the thick portion at the edge of the sheet molded article is easily pressed, the transfer rate was relatively improved. In contrast, in comparative example 3, the average transfer rate in the middle part of the sheet molded article (film molded article) having been molded was 75% and the average transfer rate in the end part was 71%, so a significant difference in the average transfer rate was observed between the middle part and the end part.

[0084] The shaping roll for melt extrusion molding (first roll), the shaping roll assembly for melt extrusion molding, and the melt extrusion molding method using the first roll according to embodiment 3 can be the same as the first roll, the shaping roll assembly for melt extrusion molding, and the melt extrusion molding method using the first roll according to embodiment 1 or 2 except the points described above, so detailed descriptions are omitted.

[0085] As illustrated in FIG. 3B, the surface of the second cylinders 13 may be covered with extension parts 12B of the first cylinder. In such implementation, the plating layer 14 is formed on the surface of the first cylinder 12.

Embodiment 4

[0086] Embodiment 4 relates to the shaping roll for melt extrusion molding, the shaping roll assembly for melt extrusion molding, and the melt extrusion molding method according to the second aspect of the invention. FIG. 4A is a cross sectional view schematically illustrating a shaping roll (first roll) 1D for melt extrusion molding according to embodiment 4 when the first roll 1D is taken along a virtual plane including the axial line and FIG. 4B is a cross sectional view schematically illustrating a roll body part 30. A conceptual view illustrating the disposition of the die and the shaping roll assembly for melt extrusion molding is the same as that illustrated in FIG. 1B.

[0087] The first roll 1D according to embodiment 4 is a shaping roll for melt extrusion molding used for melt extrusion molding of thermoplastic resin and comprises

[0088] the roll body part 30 having the heat medium passage 11 internally and cutouts 32 on outer surfaces of both end portions 31 and

[0089] cylindrical members 33 fitted into the cutouts 32 in the both end portions 31 of the roll body part 30. The roll body part 30 is made of a first metal material having a thermal conductivity of 40 W/m.Math.K or more, the cylindrical members 33 are made of a second metal material having a thermal conductivity of 20 W/m.Math.K or less, and the cylindrical members 33 are at least partially joined to the cutouts 32 of the roll body part 30. The first metal material of the roll body part 30 and the second metal material of the cylindrical members 33 are specifically indicated in Table 7 below.

[0090] The cylindrical members 33 are shrink-fitted to the roll body part 30. The value of the inner diameter D.sub.2-i of the cylindrical members 33 at normal temperatures, the outer diameter D.sub.1-o in the cutouts 32 of the roll body part 30 at normal temperatures, and an outer diameter D.sub.1-o in a portion 30A of the roll body part 30 between the cutout 32 and the cutout 32 at normal temperatures are indicated in Table 7 below. That is, the shrink-fitting margin is assumed to be 0.15 mm. In addition, the wall thickness of the cylindrical members 33 is assumed to be 8 mm. Also in embodiment 4, the roll body part 30 is assumed to be a so-called drilled roll having the heat medium passage 11 formed into a circular pipe by a cutting drill so as to extend from the side of the roll body part 30 in parallel with the axial direction. The number of heat medium passages 11 is essentially arbitrary. Thermal oil is used as the heat medium of the roll body part 30. Although the linear expansion coefficient of the second metal material of the cylindrical members 33 is slightly larger than the linear expansion coefficient of the first metal material of the roll body part 30, it is possible to prevent the cylindrical members 33 from being loosened by making the shrink-fitting margin slightly larger. In some cases, the end parts of the cylindrical members 33 may be spot-welded to the roll body part 30 to prevent them from rotating idle or being removed.

[0091] On the surfaces of the roll body part 30 and the cylindrical members 33, the same plating layer 14 as in embodiment 1 was formed. In addition, as in embodiment 2, the same rubber roll made of fluororesin similar as the second roll 2 in embodiment 1 was used as the second roll 2.

[0092] When the width of the sheet molded article shaped by melt extrusion molding using the shaping roll for melt extrusion molding is W.sub.0 and the length of the portion of the roll body part 30 between the cutouts 32 of the roll body part 30 is X.sub.1, the following expression is met.

W.sub.0>X.sub.1

Alternatively, the following expression is met.

30 mmW.sub.0X.sub.1300 mm

In addition, when the length of the cylindrical members 33 is X.sub.2, the following expression is met.

30 mmX.sub.2300 mm

In addition, the following expression is met.

(X.sub.1+2.Math.X.sub.2)>W.sub.0+30 (mm)

The values of X.sub.1 and X.sub.2 and the value of W.sub.0 are specifically indicated in Table 7 below. The state in which the region of X.sub.2 overlaps the end part of the sheet molded article by 30 mm or more is preferable.

TABLE-US-00007 TABLE 7 First metal material S45C Thermal conductivity 45 W/m .Math. K Linear expansion coefficient 12 10.sup.6 mm/mm .Math. K Second metal material SUS309 Thermal conductivity 14 W/m .Math. K Linear expansion coefficient 15 10.sup.6 mm/mm .Math. K D.sub.1-o 384.0 mm D.sub.1-o 400.0 mm D.sub.2-I 383.7 mm D.sub.2-o 400.0 mm X.sub.1 300 mm X.sub.2 195 mm W.sub.0 450 mm

[0093] In embodiment 4, polycarbonate resin (polycarbonate resin lupilon E2000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the thermoplastic resin. In addition, the nominal thickness of a sheet molded article (film molded article) obtained by a melt extrusion molding method according to embodiment 4 is 130 m and the width W.sub.0 is indicated in Table 7. The obtained sheet molded article (film molded article) is a light diffusion sheet (light diffusion film) as in embodiment 1 and a mat pattern is formed thereon.

[0094] Also in embodiment 4, a well-known melt extrusion molding apparatus is used to pass molten thermoplastic resin pushed out of the die through the gap between the first roll 1D and the second roll 2 and apply a pressure to the sheet type molten thermoplastic resin to obtain the sheet molded article (film molded article). The molding conditions are indicated in Table 8 below. The appearance of the obtained light diffusion sheet (light diffusion film) was good and the difference in the haze value was hardly observed between the middle part and the end part.

TABLE-US-00008 TABLE 8 Die temperature 280 C. Line speed 7 m/min First roll temperature 135 C. Second roll temperature 70 C. Line pressure level 6 kg/cm

[0095] Although the invention has been described above based on preferable embodiments, the invention is not limited to these embodiments. The structures, composition, and materials used, melt extrusion molding conditions, and the like of the shaping roll for melt extrusion molding, the shaping roll assembly for melt extrusion molding, and the melt extrusion molding apparatus described in the embodiments are only examples and may be changed as appropriate. For example, the plating layer described in embodiment 2 may be applied to embodiment 1 and embodiment 4 and the plating layer described in embodiment 1 may be applied to embodiment 2 and embodiment 3.

DESCRIPTION OF REFERENCE NUMERALS

[0096] 1A, 1B, 1C, 1D: first roll [0097] 2: second roll [0098] 10, 20, 30: roll body part [0099] 11, 21: heat medium passage [0100] 12, 22: first cylinder [0101] 12A, 12B: extension part of first cylinder [0102] 13, 23, 113: second cylinder [0103] 14, 24: plating layer [0104] 25: dividing wall [0105] 31: both end portions of first roll 1D [0106] 32: cutout [0107] 33: cylindrical member