Automotive exterior panel and method for producing the same

Abstract: The present invention relates to a blow moulded article with a smooth appearance and to the method of making the article. More particularly, the blow-moulding system of the present invention utilizes a thermal cycle to eliminate certain moulding defects and a non-mirrored mould cavity surface to eliminate other moulding defects. The thermal cycle sets the cavity temperature to a prescribed range to eliminate spot marks and line marks. The mould cavity surface has minute concavities/convexities and thereby produces an article with minute concavities/convexities such that when the article is painted, a smooth surface is produced without the need for sanding either the mould surface or the paint surface.

Description: FIELD OF THE INVENTION The present invention relates to an automotive exterior panel according to claim 1 having a good appearance and smooth finish and to a method according to claim for producing the panel. BACKGROUND OF THE INVENTION Spot marks and the line marks are created on the external face of blow moulded hollow articles of resin according to the conventional prior art technologies, and are known to be caused by rough surface, die lines, and granular structures created on the external face of the parison. The rough surface is caused by the flow of fused resin passing through the extrusion head when the parison is extruded and the rough surface is made up of irregular concave and convex portions having a height of about 2 µm or greater. The die line is caused by the junction of fused resin in the direction of flow thereof in the extrusion head when the parison is extruded and the die line is a streaky dent having a depth in the range of from 2 to 500 µm. The granular structure is caused by an unmelted particle or carbide of resin and the granular structure is a 2 to 1000 µm protrusion or dent on the external face of parison. Conventional methods for producing hollow moulded articles having a smooth appearance disclose a method comprising disposing a'parison, which is composed of a non-crystalline resin exhibiting a tensile modulus of 2000 Kg/cm 2 at 75°C or above, between mould halves having mirror-finished cavity surface, closing the mould and closely adhering the parison to the cavity by blowing a pressurising air into the parison, wherein the parison is adhered to the cavity which is set to a cavity temperature Y °C falling in the following range: Y °C = (0.96 X 0 - 37) to (0.96 X 0 + 3) where X 0 is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 (Japanese Patent Application Publication (JP-B) No. 6-22875). With this method it is impossible to avoid the formation of spot marks or line marks on the external surface of the hollow article of non-crystalline resin. Therefore, when producing an automotive exterior panel whose appearance needs to meet strict requirements, the spot marks and the line marks need to be removed by polishing or wet-sanding the external surface of the blow-moulded hollow article of non-crystalline resin prior to the painting of the external surface. Consequently, the number of process steps increases and production costs become higher. Another prior art method for thermoforming or blow moulding a thermoplastic resin, is described in JP-B No. 1-27849, wherein the gloss of the surface of the moulded article is increased by heating selectively and instantly the mould surface to a temperature higher than the thermal deformation temperature of the resin by means of high frequency induction heating. This method suffers has significant drawback, because it is necessary to use a special moulding apparatus equipped with a mould heating device designed for the high frequency induction-heating. Consequently, the production costs become higher. In JP-B No. 2-40498 there is disclosed a method comprising blow-moulding a molten parison, which has on the surface thereof many minute concavities/convexities having a depth in the range of from 2 to 100 µm, by means of a mould which is heated to a temperature higher than the crystallisation temperature of the resin and the surface of which is mirror-finished to a roughness of 0.5µm or less. The melt fracture is generated on the parison surface so as to create many minute concavities/convexities having a depth in the range of from 2 to 100µm. The depth of the minute concavities/convexities are difficult to control, and the resulting article has a certain amount of surface roughness even after painting. However, the control of the melt fracture is difficult and therefore is not suited for mass production. What is needed is an article that can be produced efficiently and in mass production that has a smooth appearance once painted, suitable for an automobile exterior panel. The process used to create such a panel should eliminate line marks, spot marks, and air marks. The process should allow for mass production and produce a cost-effective product. After extensive experimentation, the present inventors have found that the formation of spot marks and line marks, which appear on the external face of the moulded article due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be prevented by blow moulding by the use of a mould having minute concavities/convexities comprising a specific surface roughness and average peak-to-peak distance and by carrying out the blow moulding at a cavity surface temperature set to a specific temperature, instead of using a mould having a mirror-finished cavity surface. This finding is a surprising fact from the standpoint of traditional knowledge, and this finding is important from two aspects. One aspect is that the problem of spot marks and line marks, which appear on the external face of the blow moulded article due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be eliminated by setting the cavity surface temperature to a specific temperature. The defects, such as spot marks and line marks, which are created on the parison surface when the parison is extruded, can be eliminated by raising the surface temperature of the parison to a specific temperature. In other words, because of the cavity surface temperature, the parison undergoes a kind of thermal treatment. As a result, the defects, such as spot marks and line marks, which cannot be eliminated by conventional technologies, can be eliminated as describe above. The thermal treatment can be compared with ironing, wherein the heat takes wrinkles out of clothing. Indeed, the defects, such as spot marks and line marks, which are created on the parison surface due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be eliminated by a treatment which comprises raising the cavity surface temperature to a specific temperature. However, it has become clear that this treatment causes a crater-like defect, which is called an air mark, on the surface of the blow moulded article. If the blow-moulded article is painted without removing the air mark, the air mark is reflected to the paint film surface. Therefore, it is necessary to remove the air mark by polishing or wet-sanding prior to the application of paint, as hitherto practised. In addition, it has become clear that the air marks are more concentrated on complicated portions of the blow moulded article as the shape of the blow moulded article becomes complicated. So while thermal treatment can eliminate spot marks and line marks, the air marks create a defective article. It was revealed through research, that the formation of minute concavities/convexities on the cavity surface, in such a manner that the surface roughness is in the range of from 0.9 to 9.0 µm and the average peak-to-peak distance is in the range of from 10 to 150 µm, prevents the formation of the air mark. And, it provides excellent surface results which make the polishing or wet-sanding unnecessary. This is true even if the surface roughness of the cavity is greater than the surface roughness of the parison. Specific minute concavities/convexities, particularly those whose average peak-to-peak distance is in the range of from 10 to 150 µm, have a beneficial effect on paint film. This is because, when the blow moulded article is painted, the paint penetrates into the minute concavities/convexities by a uniform capillary action and thus provides a defect-free smooth painted surface. According to the measurement conducted by the present inventors, the surface roughness of the parison after extrusion thereof was 3 µm and the average peak-to-peak distance was 539 µm. If the parison surface, whose average peak-to-peak distance is large despite the fairly small surface roughness, is not treated and is then painted, paint film defects such as orange peel emerge due to the emergence of the irregularities on the paint film because the peaks and valleys on the surface of the blow moulded article cannot be fully covered and filled with the paint film. Thus, the combination of the thermal treatment in conjunction with the prescribed surface roughness of the mould cavity eliminates the line marks, spot marks, and air marks and produce a quality appearance. The present invention has been achieved based on the finding that the formation of spot marks and line marks, which appear on the external face of the blow moulded article due to the presence of rough surface, die lines and annular structures on the external face of the parison, can be prevented by blow moulding by the use of a mould having minute concavities/convexities comprising a specific surface roughness and average peak-to-peak distance and by carrying out the blow moulding at cavity surface temperature set to a specific temperature, instead of using a mould having a mirror-finished cavity surface. Accordingly, it has become clear that a beautiful paint film free of defects, such as orange peel, can be obtained if the substrate automotive exterior panel is an automotive exterior panel which is a hollow blow moulded article of a non-crystalline resin exhibiting a tensile modulus of 2000 Kg/cm 2 at 75°C or above and which is coated with a 15 to 150 µm thick paint film, wherein the substrate surface to be coated has specific irregularities comprising a surface roughness in the range of from 0.9 to 9.0 µm and an average peak-to-peak distance in the range of from 10 to 150 µm. Further, it has become clear that a beautiful paint film free of defects, such as orange peel, can be obtained if the substrate automotive exterior panel is an automotive exterior panel which is a hollow blow moulded article of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm 2 or more at 23°C and which is coated with a 15 to 150 µm thick paint film, wherein the substrate surface to be coated has specific irregularities comprising a surface roughness in the range of from 0.9 to 9.0 µm and an average peak-to-peak distance in the range of from 10 to 150 µm. In addition, this automotive exterior panel was found to have the mechanical strengths, such as rigidity, which meet the requirement for automotive exterior panels. In this case, if the crystalline resin exhibiting a flexural modulus of 9000 Kg/cm 2 or more at 23°C is incorporated with 3% to 35% by weight of an inorganic filler, the parting lines, which emerge on the blow moulded article for automotive exterior panel, can be easily eliminated by an ordinary treatment such as sanding. If the amount of the inorganic filler is less than 3% by weight, the surface of the moulded article cannot be finished to the prescribed surface roughness because of the formation of, for example, splits when the parting lines are being eliminated by sanding or the like. On the contrary, if the amount of the inorganic filler is more than 35% by weight, the moulded article becomes so hard that disadvantages, such as reduction in the smoothness of the paint film, reduction in formability and impairment of physical properties of the product emerge. SUMMARY OF THE INVENTION Accordingly, the present invention provides an automotive exterior panel according to claim 1. The crystalline resin may comprise 3% to 35% by weight of an inorganic filler, and is preferably polypropylene. A method of the present invention for producing the automotive exterior panel is recited in claim 5. In the first method of the present invention for producing the automotive exterior panel, it is effective to set the cavity surface temperature Z°C, at which a mould opening process is completed for taking out the moulded article for automotive exterior panel, to a temperature in the range of Z ≤0.9X where X is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 . The invention also provides a A method of producing an automotive exterior panel, according to claim 7. In the method of the present invention for producing the automotive exterior panel, it is effective to incorporate 3% to 35% by weight of an inorganic filler into the crystalline resin. Further, it is effective to choose a temperature in the range of Z≤ A - 15 for the cavity surface temperature (Z°C) at which a mould opening process is started for taking out the moulded article for automotive exterior panel. Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only a preferred embodiment of the invention is described, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realised, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: FIG. 1(a) is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mould halves. FIG. 1(b) is an exploded view of the surface of the parison, showing the rough surface. FIG. 2(a) is a diagrammatic cross-sectional view illustrating the state where mould is opened after a blow-moulded article is produced FIG. 2(b) is an exploded view of the cavity surface, showing the smooth surface. FIG. 3 is a view showing the prior art irregular surface after painting. FIG. 4 is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mould halves. FIG. 5(a) is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mould halves. FIG. 5(b) is an exploded view of the surface of the cavities, showing the concavities/convexities. FIG. 6 is a view showing the smooth outer surface after painting. FIG. 7 is an oblique view illustrating a blow-moulded article for a spoiler. DESCRIPTION OF THE PREFERRED EMBODIMENT In the prior art, as shown in FIG. 1(a), a parison 5, is extruded from an extrusion head 10 into the space between mould halves 35, 40. An exploded view of the parison surface is illustrated in FIG. 1(b). The rough surface, die lines, and granular structures are evident on the external face of the parison, which has irregular and relatively large concavities/convexities such that the surface roughness exceeds 10 µm and the peak-to-peak distance is exceeds 150 µm. The rough surface is caused by the flow of fused resin passing through the extrusion head 10 when the parison 5 is extruded and the rough surface is made up of irregular concave and convex portions having a height of about 2 µm or greater. The die line is caused by the junction of fused resin in the direction of flow thereof in the extrusion head 10 when the parison 5 is extruded and the die line is a streaky dent having a depth in the range of from 2 to 500 µm. The granular structure is caused by an unmelted particle or carbide of resin and the granular structure is a 2 to 1000 µm protrusion or dent on the external face of parison 5. Once the mould is closed, and the parison 5 is sandwiched between the mould halves 35, 40, a blow moulded article 50 for an automotive exterior panel is produced, as shown in FIG. 2(a). The inner surface of mould halves 35, 40 have a mirror finish in the prior art, and the imperfections of the parison are transferred to the final product, resulting in spot marks and line marks. If the mould halves are properly treated with heating, the spot marks and line marks can be alleviated, but the heating process produces air marks, also resulting in unsatisfactory product. The prior art finished article 50 that results after the mould halves 35, 40 have compressed and released, produce an article with a rough surface as shown in FIG. 3. The paint surface 110 follows the rough and irregular mould surface 100 to produce an article of shoddy appearance. The mould surface and/or the paint surface can be sanded and produce a smoother appearance, but this is an extra process and significantly increases production costs. The prior art also discusses using an irregular minute concavities/convexities having a depth in the range of from 2 to 100 µm, by means of a mould which is heated to a temperature higher than the crystallisation temperature of the resin and the surface of which is mirror-finished to a roughness of 0.5µm or less. The final product using this system is also not acceptable quality. The present invention is shown in FIG. 4, where a parison 5, which is composed of a non-crystalline resin exhibiting a tensile modulus of 2000 Kg/cm 2 at 75°C or above, is extruded from an extrusion head 10 into the space between mould halves 35, 40. Once the mould is closed, and the parison 5 is sandwiched between the mould halves 35, 40. In FIG. 5(a), a blow moulded article 50 is produced by a blow-moulding operation comprising introducing pressurised air having a pressure of 7 Kg/cm 2 into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20. An exploded view of the minute concavities/convexities of the inner cavities of the mould halves surface 15, 20 is illustrated in FIG. 5(b), with the minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 µm and the average peak-to-peak distance is in the range of from 10 to 150 µm. In this step, it is important to set the surface temperature Y°C of the cavities 15, 20 to a temperature within the range Y = (0.96 X + 3) to (0.96 X + 40), by using a heating means which is transmitted through cavities or ducts 25, 30. The heating medium includes heated water, steam or an oil, where X°C is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 , at the time when the parison 5 is adhered to the cavities 15, 20 or after the parison 5 is adhered to the cavities 15, 20. Following the thermal process, a blow moulded article 50 for automotive exterior panel is cooled in the mould halves 35, 40 and the mould is then opened as shown in FIG. 5(a). Next, the moulded article 50 is taken out and unnecessary flushes are removed. As a modified method for obtaining a moulded article 50 for automotive exterior panel, which is free of deformation after release from the mould and which has a beautiful appearance, the cavity surface temperature Z°C, at which a mould opening process is completed for taking out the moulded article for automotive exterior panel, is set to a temperature in the range of Z≤0.9X where X°C is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 . Finally, a paint is applied to the external surface of the moulded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel. The details of the second embodiment of the method of the present invention for producing the automotive exterior panel described as follows. As shown in FIG. 4, a parison 5, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm 2 or more at 23°C , is extruded from an extrusion head 2 into the space between mould halves 35, 40 whose cavities 15, 20 have minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 µm and the peak-to-peak distance is in the range of from 10 to 150 µm. The mould is closed, and the parison 5 is sandwiched between the mould halves 35, 40. Next, a blow moulded article 50 for automotive exterior panel is produced by a blow moulding operation comprising introducing pressurised air having a pressure of 7 Kg/cm 2 into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20. In this step, the surface temperature Y°C of the cavities 15, 20, which hold the parison 5 adhered thereto, is raised to a temperature within the range A < Y < 1.07B by using a heating ducts 25, 30 which is provided in the cavities 35, 40 and which utilises a heating means such as heated water, steam or a heated oil, where A is a peak crystallisation temperature (°C) in a DSC curve (defined at Japan Industrial Standard (JIS) K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C; and B is a peak fusion temperature (°C) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C. Next, a hollow moulded article 50 for automotive exterior panel is cooled in the mould halves 35, 40 and the mould is then opened as shown in FIG. 5(a). Then, the blow moulded article 50 is taken out and unnecessary flushes are removed. In this step, a moulded article 50 for automotive exterior panel, which is free of deformation after release from the mould and which has a beautiful appearance, can be obtained, if the cavity (15, 20) surface temperature Z°C, at which a mould opening process is started for taking out the moulded article for automotive exterior panel, is set to a temperature in the range of Z ≤ A - 15. After removing the article, parting line portions are removed by sanding and thereafter a paint is applied at a thickness of from 15 to 150 µm to the external surface of the moulded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel. The details of the third embodiment of the method of the present invention for producing the automotive exterior panel are shown in FIG. 4, wherein a parison 5, which is composed of a crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C, is extruded from an extrusion head 10 into the space between mould halves 35, 40. The mould halves 35, 40 have cavities 15, 20 with minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 µm and the average peak-to-peak distance is in the range of from 10 to 150 µm. The mould halves 35, 40 are closed, and the mould is heated by using heating ducts 25, 30 so that the surface temperature Y°C of the cavities 15, 20 at the point immediately before the mould closure is a temperature within the range A < Y < 1.07B, where A is a peak crystallisation temperature (°C) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C; and B is a peak fusion temperature (°C) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C. After the mould halves 35, 40 are closed, a hollow moulded article 50 for automotive exterior panel is produced by a blow-moulding process comprising introducing pressurised air having a pressure of 7 Kg/cm 2 into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20. The hollow moulded article 50 for automotive exterior panel is cooled in the mould halves 35, 40 and the mould is then opened as shown in FIG. 5(a). Next, the moulded article 50 is taken out and unnecessary burrs are removed. The moulded article 50 for automotive exterior panel, which is free of deformation after release from the mould and which has a beautiful appearance, can be obtained if the cavity surface temperature Z°C, at which a mould opening process is started for taking out the moulded article for automotive exterior panel, is set to a temperature in the range of Z≤A - 15. Any parting line portions are removed by sanding and thereafter a paint is applied at a thickness of from 15 to 150 µm to the external surface of the moulded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel. The work product of the present method is shown in FIG. 6. The mould surface 120 has minute concavities/convexities such that the overall peak to valley distance (Rt) is less than 10 µm, and the peak-to-peak distance (Sm) is less than 150 µm. The paint surface 130 has a smooth surface that does not require any additional sanding. The smooth surface results from the present invention, wherein the paint fills in the minute concavities/convexities by a capillary action. The term "automotive exterior panel" as used herein means a spoiler, a bumper, a trunk lid, a side mole, a fender, a bonnet, and the like, for which so-called good appearance, such as glossy surface, brilliant colour, and the like, is strictly required. In the present invention, the tensile strength refers to a value obtained by a tensile rate of 2 mm/minute by using a No. 2 type test piece in accordance with JIS K 7113. Even if the test pieces belong to the same non-crystalline resin, the tensile strength differs depending on the individual properties of resin for the test pieces. A non-crystalline resin, which exhibits a tensile modulus of 2000 Kg/cm 2 at 75°C or above or preferably at 85°C or above, is excellent in heat resistance. Examples of these resins include modified polyphenylene oxide, polycarbonate, non-crystalline polyamide, ABS resins, and polysulfone. Examples of a blend comprising a non-crystalline resin includes a blend of an ABS resin and polycarbonate. In the present invention, the non-crystalline resin may be a blend of a non-crystalline resin and a crystalline resin wherein the non-crystalline component accounts for 30% by weight or more and wherein the blend exhibits a tensile modulus of 2000 Kg/cm 2 at 75°C or above. Examples of the blend of a non-crystalline resin and a crystalline resin include a blend of modified polyphenylene oxide and polyamide and a blend of polycarbonate and polybutylene terephthalate. The flexural modulus at 23°C in the present invention is a value obtained in accordance with JIS K 7171. A crystalline resin which exhibits a flexural modulus of 9000 Kg/cm 2 or more at 23°C meets the mechanical strengths, such as rigidity, required for an automotive exterior panel. Examples of these resins include a single resin, such as polypropylene, high-density polyethylene, polyamide (e.g., nylon) and polybutylene terephthalate; a blend (alloy) of a crystalline resin and a non-crystalline resin wherein the crystalline resin accounts for 30% by weight or more; and a blend (alloy) of these crystalline resins. Examples of a blend (alloy) of a crystalline resin and a non-crystalline resin include a polyamide-modified polyphenylene ether blend and a polypropylene-polystyrene blend. Examples of a blend (alloy) of crystalline resins include a polypropylene-polyethylene blend. In the present invention, the peak crystallisation temperature is a peak crystallisation temperature in a DSC curve in accordance with JIS K 7121, and the peak fusion temperature is a peak fusion temperature in a DSC curve in accordance with JIS K 7121. In the case of a blend (alloy) of a crystalline resin and a non-crystalline resin, the peak crystallisation temperature and the peak fusion temperature of the crystalline resin constituting the blend (alloy) are indicated as the peak crystallisation temperature and the peak fusion temperature of the blend (alloy), respectively. In the case of a blend (alloy) of crystalline resins and non-crystalline resins, it has been found that the peak crystallisation temperature and the peak fusion temperature, which are each sought from the additive average corresponding to the blending ratio of each crystalline resin, can serve as the peak crystallisation temperature and the peak fusion temperature of the blend (alloy), respectively. For example, the peak fusion temperature B of a blend resin, in which a crystalline resin (a) has a blending ratio of a% and a peak fusion temperature t 1 , while other crystalline resin (b) has a peak fusion temperature t 2 , is expressed as follows: B = (a/100) t 1 + (1 - b/100) t 2 However, in the case where the peak fusion temperatures of the two crystalline resins (a) and (b) are so close to each other that the peaks in the DSC curves are not clearly differentiated from each other, the top of the peaks of the DSC curves was taken as the peak fusion temperature of the blend. In a similar way, the peak crystallisation temperature can be obtained. Table 1 shows the peak crystallisation temperature and the peak fusion temperature of representative crystalline resins for use in the present invention. CRYSTALLINE RESINS PEAK CRYSTALLISATION TEMPERATURE (°C) PEAK FUSION TEMPERATURE (°C) POLYPROPYLENE 115 162 HIGH-DENSITY POLYETHYLENE 121 130 POLYAMIDE (6 NYLON) 192 222 POLYBUTYLENE TEREPHTHALATE 198 217 The surface irregularities formed on the outer face of blow moulded automotive exterior panel and the minute concavities/convexities on the cavity of mould comprise a surface roughness in the range of from 0.9 to 9.0 µm, respectively. The surface roughness is based on maximum heights obtained by testing the surface of the cavity and blow moulded article with an electrical roughness tester based on a needle tracer method (JIS B 0601), and more specifically, the surface roughness is calculated from the sum of the maximum height of the peak (convexity) and the maximum depth (concavity) of the irregularities on the outer face or on the minute concavities/convexities. Since the surface of a blow moulded article in particular often exhibits a gentle slope, the maximum height Rmax (JIS B 0601) of sectional-area curve is not used for expressing the surface roughness in the present invention. Instead, the present invention uses the sum of the maximum height of the peak (convexity) and the maximum depth (concavity), sought from the roughness curve (JIS B 0601), for expressing the surface roughness. In this case, the cut-off value of the roughness curve was 0.8 mm. The average peak-to-peak distance of the irregularities formed on the outer face of the blow moulded article for automotive exterior panel and the average peak-to-peak distance of the minute concavities/convexities of the cavity of mould for use in the present invention are in the range of from 10 to 150 µm. The average peak-to-peak distance is an average distance obtained by testing the surface of the cavity and blow moulded article with an electrical roughness tester based on a needle tracer method. For the measurement, five sites were arbitrarily selected and the measurements were conducted for a breadth of 4 mm for each site. The average peak-to-peak distance Sm is the average of distances between a peak point facing a valley and a next peak point facing a valley in cross sections traversing parallel lines in the portions for measurement cut out of a sectional-area curve (JIS B 0601). In this case, the multiplying factor in longitudinal relation to the roughness was 20000 or 10000, while the multiplying factor in transverse relation to the roughness was 50. For the purpose of creating minute concavities/convexities having a surface roughness in the range of from 0.9 to 9.0 µm and an average peak-to-peak distance in the range of from 10 to 150 µm, an appropriate surface treatment is sand blasting by using sand having sizes in the range of from #150-grit to #1000-grit. The application of a paint to the external face of the moulded article for automotive exterior panel is conducted by forming a 15 to 150 µm thick paint film by a conventional procedure using an air-spray gun. The paint adheres to the minute concavities/convexities through a capillary action and creates a smooth appearance. EXAMPLES In order to confirm the effects of the present invention, the following experiments were conducted, and the results are explained below. In the experiments, blow moulded articles 150 for spoiler as shown in FIG. 7, each having a length L of 1200 mm, and a breadth D of 180 mm, a height H of 90 mm and an average wall thickness of 3 mm, were prepared by blow moulding using a blow-moulding machine equipped with an extruder having a screw whose diameter was 90 mm. Spoilers were prepared by painting the external face of the moulded articles 150 for spoiler at a paint film thickness of 50 µm. In Examples 1-5, minute concavities/convexities were formed on the cavity of a mould by sand blasting so that the surface roughness was 5.0 µm and the average peak-to-peak distance was 25 µm. A parison of an ABS resin (YM-254 having X of 105°C and manufactured by Technopolymer Co., Ltd.) was extruded at 240°C and samples were prepared by changing the cavity surface temperature. Example 6 is a comparative example to be compared with Example 2. In Example 6, the procedure of Example 2 was repeated to prepare samples, except that the cavity of the mould used in Example 6 had a mirror-finished cavity surface. In Example 7, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 7 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 µm and the average peak-to-peak distance was 9.0 µm. In Example 8, Samples 1- 9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 8 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 µm and the average peak-to-peak distance was 10 µm. In Example 9, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 9 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 150 µm. In Example 10, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 10 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 160 µm. In Example 11, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 11 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 µm and the average peak-to-peak distance was 25 µm. In Example 12, Samples 1- 9 were prepared by repeating the procedure of Example 2, except that the mould used in Example 12 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 µm and the average peak-to-peak distance was 25 µm. In Examples 13 -15, minute concavities/convexities were formed on the cavity of a mould by sand blasting so that the surface roughness was 5.0 µm and the average peak-to-peak distance was 25 µm. A parison of a modified PPO resin (Noryl EBM-9201 having X of 114°C and manufactured by Japan GE Plastics Co., Ltd.) was extruded at 240°C and samples were prepared by changing the cavity surface temperature. In Examples 16 - 22, minute concavities/convexities were formed on the cavity of a mould by sand blasting so that the surface roughness was 5.0 µm and the average peak-to-peak distance was 25 µm. A parison made of a polypropylene resin (EC-9 having A of 115°C and B of 162°C and manufactured by Nippon Polychem Co., Ltd.) incorporated with 10% by weight of talc as an inorganic filler was extruded at 220°C and samples were prepared by changing the cavity surface temperature. In Example 23, Samples 1 - 9 were prepared by using a mould which had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 25 µm and by changing the content of the inorganic filler while keeping the cavity surface temperature constant. In Example 24, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 24 had minute concavities/convexities on the cavity such that the surface roughness was 2.0 µm and the average peak-to-peak distance was 10 µm. In Example 25, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 25 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 µm and the average peak-to-peak distance was 10 µm. In Example 26, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 26 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 µm and the average peak-to-peak distance was 10 µm. In Example 27, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 27 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 µm and the average peak-to-peak distance was 10 µm. In Example 28, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 28 had minute concavities/convexities on the cavity such that the surface roughness was 9.0 µm and the average peak-to-peak distance was 30 µm. In Example 29, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 29 had minute concavities/convexities on the cavity such that the surface roughness was 10 µm and the average peak-to-peak distance was 30 µm. In Example 30, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 30 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 µm and the average peak-to-peak distance was 10 µm. In Example 31, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 31 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 µm and the average peak-to-peak distance was 9 µm. In Example 32, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 32 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 150 µm. In Example 33, Samples 1 - 9 were prepared by repeating the procedure of Example 20, except that the mould used in Example 33 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 160 µm. In Example 34, minute concavities/convexities were formed on the cavity of a mould by sand blasting so that the surface roughness was 5.0 µm and the average peak-to-peak distance was 25 µm. Sample 1 - 9 were prepared by extruding a parison made of a polypropylene-high-density polyethylene blend resin at 210°C and by changing the cavity surface temperature. The polypropylene-high-density polyethylene blend resin was prepared by blending polypropylene resin (EC-9 having A of 115°C and B of 162°C and manufactured by Nippon Polychem Co., Ltd.) and high-density polyethylene (B-970 having A of 121°C and B of 130°C and manufactured by Asahi Chemical Industry Co., Ltd.) at a ratio of 70 : 30. The peak temperatures of the blend resin were 116.8°C for A and 152.4°C for B. In Example 35, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except the content of the inorganic filler in Example 35 was changed while keeping the cavity surface temperature constant. In Example 36, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 36 had minute concavities/convexities on the cavity such that the surface roughness was 2.0 µm and the average peak-to-peak distance was 10 µm. In Example 37, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 37 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 µm and the average peak-to-peak distance was 10 µm. In Example 38, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 38 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 µm and the average peak-to-peak distance was 10 µm. In Example 39, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 39 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 µm and the average peak-to-peak distance was 10 µm. In Example 40, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 40 had minute concavities/convexities on the cavity such that the surface roughness was 9.0 µm and the average peak-to-peak distance was 30 µm. In Example 41, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 41 had minute concavities/convexities on the cavity such that the surface roughness was 10 µm and the average peak-to-peak distance was 30 µm. In Example 42. Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 42 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 µm and the average peak-to-peak distance was 9 µm. In Example 43, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 43 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 µm and the average peak-to-peak distance was 10 µm. In Example 44, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 44 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 150 µm. In Example 45, Samples 1 - 9 were prepared by repeating the procedure of Example 34, except that the mould used in Example 45 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 µm and the average peak-to-peak distance was 160 µm. The evaluation results of Examples 1 - 45 are shown in Tables 2-1 -Tables 2-45. In Tables 2-1 - Tables 2-45, evaluation criteria are as follows: In the tables: Rt - indicates the surface roughness in µm; Sm - indicates an average peak-to-peak distance in µm of the irregularities on the surface of moulded articles. Note: Deformation, surface condition, air marks, die lines, and bits were visually inspected after blow moulding but before painting the moulded articles. Deformation NONE: no deformation observed SOME: slight deformation but judged as acceptable YES: deformation observed Surface condition NONE: no shark skin irregularities observed on the surface and the surface is uniform SOME: slight shark skin irregularities observed on the surface YES: remarkable shark skin irregularities observed on the surface Air marks NONE: no air mark observed SOME: almost no air mark observed YES: air mark observed Die lines NONE no die line observed SOME: almost no die line observed YES: die lines observed Bits NONE: no bits observed SOME: almost no bits observed YES: bits observed Appearance of paint film NONE: no orange peel observed SOME: slight orange peel observed YES: orange peel observed Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 1-1 60 70 140 NONE YES NONE YES YES 6.4 190 YES Example 1-2 60 80 140 NONE YES NONE YES YES 5.8 188 YES Example 1-3 60 90 140 NONE YES NONE YES YES 5.4 185 SOME Example 1-4 60 100 140 NONE YES NONE YES YES 5.3 158 SOME Example 1-5 60 105 140 NONE SOME NONE NONE SOME 4.9 148 NONE Example 1-6 60 115 140 NONE NONE NONE NONE NONE 5.2 124 NONE Example 1-7 60 125 140 NONE NONE NONE NONE NONE 5.0 70 NONE Example 1-8 60 135 150 NONE NONE NONE NONE NONE 4.9 66 NONE Example 1-9 60 145 180 NONE NONE NONE NONE NONE 5.1 25 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 2-1 70 70 120 NONE YES NONE YES YES 5.8 210 YES Example 2-2 70 80 120 NONE YES NONE YES YES 6.1 204 YES Example 2-3 70 90 120 NONE YES NONE YES YES 5.4 182 YES Example 2-4 70 100 120 NONE YES NONE YES YES 5.2 160 SOME Example 2-5 70 105 120 NONE SOME NONE NONE SOME 5.4 141 NONE Example 2-6 70 115 120 NONE NONE NONE NONE NONE 4.9 110 NONE Example 2-7 70 125 120 NONE NONE NONE NONE NONE 5.0 60 NONE Example 2-8 70 135 140 NONE NONE NONE NONE NONE 4.8 45 NONE Example 2-9 70 145 160 NONE NONE NONE NONE NONE 5.0 24 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 3-1 80 80 120 NONE YES NONE YES YES 5.6 191 YES Example 3-2 80 90 120 NONE YES NONE YES YES 5.8 175 SOME Example 3-3 80 100 120 NONE YES NONE SOME YES 6.1 154 SOME Example 3-4 80 105 120 NONE SOME NONE NONE NONE 5.4 138 NONE Example 3-5 80 115 120 NONE NONE NONE NONE NONE 5.2 60 NONE Example 3-6 80 125 120 NONE NONE NONE NONE NONE 4.9 32 NONE Example 3-7 80 135 130 NONE NONE NONE NONE NONE 5.0 28 NONE Example 3-8 80 145 150 NONE NONE NONE NONE NONE 5.0 25 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 4-1 90 90 120 NONE SOME NONE YES YES 5.5 178 YES Example 4-2 90 100 120 NONE SOME NONE SOME SOME 5.8 168 SOME Example 4-3 90 105 120 NONE SOME NONE NONE NONE 5.7 134 NONE Example 4-4 90 115 120 NONE NONE NONE NONE NONE 5.3 75 NONE Example 4-5 90 125 130 NONE NONE NONE NONE NONE 5.2 35 NONE Example 4-6 90 135 150 NONE NONE NONE NONE NONE 5.2 27 NONE Example 4-7 90 145 175 NONE NONE NONE NONE NONE 5.2 26 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 5-1 95 100 130 YES SOME NONE SOME YES 5.3 158 YES Example 5-2 95 105 130 YES SOME NONE NONE SOME 5.6 125 NONE Example 5-3 95 115 160 YES SOME NONE NONE NONE 5.4 84 NONE Example 5-4 95 125 190 YES NONE NONE NONE NONE 5.2 45 NONE Example 5-5 95 135 200 YES NONE NONE NONE NONE 5.0 32 NONE Example 5-6 95 145 200 YES NONE NONE NONE NONE 4.9 28 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 6-1 70 70 120 NONE YES NONE YES YES 5.4 185 YES Example 6-2 70 80 120 NONE YES NONE YES YES 5.2 176 YES Example 6-3 70 90 120 NONE YES NONE YES YES 4.2 170 YES Example 6-4 70 100 120 NONE YES NONE YES YES 2.4 168 YES Example 6-5 70 105 120 NONE SOME NONE NONE SOME 1.9 146 SOME Example 6-6 70 115 120 NONE NONE SOME NONE NONE 1.2 194 SOME Example 6-7 70 125 120 NONE NONE SOME NONE NONE 0.9 222 SOME Example 6-8 70 135 140 NONE NONE YES NONE NONE 0.6 201 YES Example 6-9 70 145 160 NONE NONE YES NONE NONE 0.6 176 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 7-1 70 70 120 NONE YES NONE YES YES 5.8 196 YES Example 7-2 70 80 120 NONE YES NONE YES YES 5.4 199 YES Example 7-3 70 90 120 NONE YES NONE YES YES 6.0 182 YES Example 7-4 70 100 120 NONE YES NONE YES YES 5.8 168 YES Example 7-5 70 105 120 NONE SOME NONE NONE SOME 5.9 125 SOME Example 7-6 70 115 120 NONE NONE SOME NONE SOME 5.5 69 SOME Example 7-7 70 125 120 NONE NONE SOME NONE NONE 5.4 48 SOME Example 7-8 70 135 140 NONE NONE SOME NONE NONE 3.6 28 SOME Example 7-9 70 145 160 NONE NONE SOME NONE NONE 1.2 10.5 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Condition of Coated Surface Example 8-1 70 70 120 NONE YES NONE YES YES 6.0 207 YES Example 8-2 70 80 120 NONE YES NONE YES YES 5.5 200 YES Example 8-3 70 90 120 NONE YES NONE YES YES 5.4 188 YES Example 8-4 70 100 120 NONE YES NONE YES YES 5.9 159 YES Example 8-5 70 105 120 NONE SOME NONE NONE SOME 6.4 124 SOME Example 8-6 70 115 120 NONE NONE SOME NONE SOME 5.4 69 SOME Example 8-7 70 125 120 NONE NONE SOME NONE NONE 4.8 45 SOME Example 8-8 70 135 140 NONE NONE SOME NONE NONE 1.8 24 SOME Example 8-9 70 145 160 NONE NONE SOME NONE NONE 1.2 10.6 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 9-1 70 70 120 NONE YES NONE YES YES 5.8 202 YES Example 9-2 70 80 120 NONE YES NONE YES YES 6.1 180 YES Example 9-3 70 90 120 NONE YES NONE YES YES 5.9 175 YES Example 9-4 70 100 120 NONE YES NONE YES YES 6.4 165 YES Example 9-5 70 105 120 NONE SOME NONE NONE SOME 5.6 158 SOME Example 9-6 70 115 120 NONE NONE NONE NONE NONE 6.2 155 SOME Example 9-7 70 125 120 NONE NONE SOME NONE NONE 5.8 153 SOME Example 9-8 70 135 140 NONE NONE SOME NONE NONE 5.0 156 SOME Example 9-9 70 145 160 NONE NONE SOME NONE NONE 4.9 154 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 10-1 70 70 120 NONE YES NONE YES YES 6.1 200 YES Example 10-2 70 80 120 NONE YES NONE YES YES 5.9 198 YES Example 10-3 70 90 120 NONE YES NONE YES YES 5.4 195 YES Example 10-4 70 100 120 NONE YES NONE YES YES 6.8 186 YES Example 10-5 70 105 120 NONE SOME NONE NONE SOME 5.4 188 YES Example 10-6 70 115 120 NONE NONE NONE NONE NONE 6.4 173 YES Example 10-7 70 125 120 NONE NONE SOME NONE NONE 5.8 168 YES Example 10-8 70 135 140 NONE NONE NONE NONE NONE 4.9 164 YES Example 10-9 70 145 160 NONE NONE NONE NONE NONE 5.2 160 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 11-1 70 70 120 NONE YES NONE YES YES 5.3 198 YES Example 11-2 70 80 120 NONE YES NONE YES YES 5.1 192 YES Example 11-3 70 90 120 NONE YES NONE YES YES 4.8 176 YES Example 11-4 70 100 120 NONE YES NONE YES YES 3.1 154 YES Example 11-5 70 105 120 NONE SOME NONE NONE SOME 1.9 130 SOME Example 11-6 70 115 120 NONE NONE NONE NONE NONE 1.0 65 NONE Example 11-7 70 125 120 NONE NONE NONE NONE NONE 0.9 32 NONE Example 11-8 70 135 140 NONE NONE SOME NONE NONE 0.8 27 SOME Example 11-9 70 145 160 NONE NONE SOME NONE NONE 0.9 25 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 12-1 70 70 120 NONE YES NONE YES YES 5.4 197 YES Example 12-2 70 80 120 NONE YES NONE YES YES 5.1 191 YES Example 12-3 70 90 120 NONE YES NONE YES YES 4.2 169 YES Example 12-4 70 100 120 NONE YES NONE YES YES 2.4 155 YES Example 12-5 70 105 120 NONE SOME NONE NONE SOME 1.9 129 SOME Example 12-6 70 115 120 NONE NONE SOME NONE SOME 1.5 84 SOME Example 12-7 70 125 120 NONE NONE SOME NONE NONE 0.8 36 SOME Example 12-8 70 135 140 NONE NONE SOME NONE NONE 0.7 27 SOME Example 12-9 70 145 160 NONE NONE YES NONE NONE 0.8 25 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 13-1 90 100 120 NONE YES NONE YES YES 12.0 289 YES Example 13-2 90 105 120 NONE YES NONE YES YES 8.6 260 YES Example 13-3 90 110 120 NONE SOME NONE NONE SOME 5.8 190 YES Example 13-4 90 115 120 NONE NONE NONE NONE NONE 5.4 149 NONE Example 13-5 90 120 120 NONE NONE NONE NONE NONE 5.2 76 NONE Example 13-6 90 130 120 NONE NONE NONE NONE NONE 4.9 40 NONE Example 13-7 90 140 140 NONE NONE NONE NONE NONE 5.0 35 NONE Example 13-8 90 150 160 NONE NONE NONE NONE NONE 5.1 28 NONE Example 13-9 90 170 180 NONE NONE NONE NONE NONE 5.0 26 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 14-1 80 90 120 NONE YES NONE YES YES 12.4 304 YES Example 14-2 80 100 120 NONE YES NONE YES YES 9.4 296 YES Example 14-3 80 105 120 NONE YES NONE NONE SOME 7.0 234 YES Example 14-4 80 110 120 NONE SOME NONE NONE NONE 6.0 182 NONE Example 14-5 80 115 120 NONE SOME NONE NONE NONE 5.6 140 NONE Example 14-6 80 120 120 NONE NONE NONE NONE NONE 5.2 78 NONE Example 14-7 80 130 140 NONE NONE NONE NONE NONE 5.0 42 NONE Example 14-8 80 140 160 NONE NONE NONE NONE NONE 4.9 31 NONE Example 14-9 80 150 180 NONE NONE NONE NONE NONE 5.0 25 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 15-1 70 80 120 NONE YES NONE YES YES 11.8 306 YES Example 15-2 70 90 120 NONE YES NONE YES YES 10.4 298 YES Example 15-3 70 100 120 NONE YES NONE YES YES 7.6 292 YES Example 15-4 70 105 120 NONE YES NONE SOME YES 6.9 210 YES Example 15-5 70 110 120 NONE SOME NONE NONE NONE 6.0 194 SOME Example 15-6 70 115 120 NONE NONE NONE NONE NONE 5.5 149 NONE Example 15-7 70 120 135 NONE NONE NONE NONE NONE 5.0 74 NONE Example 15-8 70 130 160 NONE NONE NONE NONE NONE 5.1 36 NONE Example 15-9 70 140 180 NONE NONE NONE NONE NONE 4.9 29 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 16-1 5 110 240 NONE YES NONE YES YES 13.8 202 YES Example 16-2 5 115 240 NONE SOME NONE SOME SOME 8.6 150 SOME Example 16-3 5 120 240 NONE SOME NONE SOME SOME 7.6 136 SOME Example 16-4 5 130 240 NONE SOME NONE NONE NONE 6.3 65 NONE Example 16-5 5 140 260 NONE SOME NONE NONE NONE 5.7 32 NONE Example 16-6 5 150 260 NONE NONE NONE NONE NONE 5.2 30 NONE Example 16-7 5 160 280 NONE NONE NONE NONE NONE 5.0 26 NONE Example 16-8 5 170 280 NONE NONE NONE NONE NONE 5.3 26 NONE Example 16-9 5 175 300 NONE NONE NONE NONE NONE 5.1 27 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 17-1 20 110 240 NONE YES NONE YES YES 14.1 210 YES Example 17-2 20 115 240 NONE SOME NONE SOME SOME 8.8 148 SOME Example 17-3 20 120 240 NONE SOME NONE SOME SOME 6.8 124 SOME Example 17-4 20 130 240 NONE SOME NONE NONE NONE 6.0 82 NONE Example 17-5 20 140 260 NONE SOME NONE NONE NONE 5.5 46 NONE Example 17-6 20 150 260 NONE NONE NONE NONE NONE 5.3 32 NONE Example 17-7 20 160 280 NONE NONE NONE NONE NONE 4.9 26 NONE Example 17-8 20 170 280 NONE NONE NONE NONE NONE 5.0 26 NONE Example 17-9 20 175 300 NONE NONE NONE NONE NONE 5.0 24 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 18-1 30 110 230 NONE YES NONE YES YES 11.5 198 YES Example 18-2 30 115 230 NONE SOME NONE SOME SOME 7.6 143 SOME Example 18-3 30 120 230 NONE SOME NONE SOME SOME 5.9 64 SOME Example 18-4 30 130 230 NONE SOME NONE NONE NONE 5.4 32 NONE Example 18-5 30 140 250 NONE SOME NONE NONE NONE 5.0 30 NONE Example 18-6 30 150 250 NONE NONE NONE NONE NONE 4.9 24 NONE Example 18-7 30 160 270 NONE NONE NONE NONE NONE 5.2 25 NONE Example 18-8 30 170 270 NONE NONE NONE NONE NONE 5.0 26 NONE Example 18-9 30 175 300 NONE NONE NONE NONE NONE 5.1 27 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 19-1 50 110 210 NONE YES NONE YES YES 10.6 164 YES Example 19-2 50 115 210 NONE SOME NONE SOME SOME 7.2 131 SOME Example 19-3 50 120 230 NONE SOME NONE SOME SOME 6.6 65 SOME Example 19-4 50 130 230 NONE NONE NONE NONE NONE 5.4 34 NONE Example 19-5 50 140 250 NONE SOME NONE NONE NONE 5.2 28 NONE Example 19-6 50 150 250 NONE NONE NONE NONE NONE 5.2 27 NONE Example 19-7 50 160 270 NONE NONE NONE NONE NONE 5.1 26 NONE Example 19-8 50 170 270 NONE NONE NONE NONE NONE 5.2 26 NONE Example 19-9 50 175 300 NONE NONE NONE NONE NONE 5.1 26 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 20-1 80 110 210 NONE YES NONE YES YES 10.4 158 YES Example 20-2 80 115 210 NONE SOME NONE SOME SOME 6.8 99 SOME Example 20-3 80 120 230 NONE NONE NONE NONE NONE 6.2 49 NONE Example 20-4 80 130 230 NONE NONE NONE NONE NONE 5.8 39 NONE Example 20-5 80 140 250 NONE SOME NONE NONE NONE 5.2 30 NONE Example 20-6 80 150 250 NONE NONE NONE NONE NONE 5.0 24 NONE Example 20-7 80 160 270 NONE NONE NONE NONE NONE 5.1 25 NONE Example 20-8 80 170 270 NONE NONE NONE NONE NONE 5.1 25 NONE Example 20-9 80 175 300 NONE NONE NONE NONE NONE 5.1 24 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 21-1 100 110 230 NONE YES NONE YES YES 10.0 154 YES Example 21-2 100 115 230 NONE NONE NONE NONE NONE 6.7 96 NONE Example 21-3 100 120 250 NONE NONE NONE NONE NONE 5.9 56 NONE Example 21-4 100 130 250 NONE NONE NONE NONE NONE 5.4 40 NONE Example 21-5 100 140 270 NONE SOME NONE NONE NONE 5.0 27 NONE Example 21-6 100 150 270 NONE NONE NONE NONE NONE 4.9 26 NONE Example 21-7 100 160 290 NONE NONE NONE NONE NONE 5.0 25 NONE Example 21-8 100 170 290 NONE NONE NONE NONE NONE 5.1 25 NONE Example 21-9 100 175 320 NONE NONE NONE NONE NONE 5.1 25 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 22-1 105 110 230 SOME YES NONE YES SOME 9.4 155 YES Example 22-2 105 115 230 SOME NONE NONE NONE NONE 5.8 72 SOME Example 22-3 105 120 250 SOME NONE NONE NONE NONE 5.4 48 SOME Example 22-4 105 130 250 SOME NONE NONE NONE NONE 5.0 28 SOME Example 22-5 105 140 270 YES NONE NONE NONE NONE 4.9 26 YES Example 22-6 105 150 270 YES NONE NONE NONE NONE 5.1 25 YES Example 22-7 105 160 290 YES NONE NONE NONE NONE 5.1 26 YES Example 22-8 105 170 290 YES NONE NONE NONE NONE 5.1 26 YES Example 22-9 105 175 320 YES NONE NONE NONE NONE 5.0 26 YES It can be seen from Tables 2-16 - Tables 2-22 that the moulding time rises to 300 seconds if the cavity surface temperature Y°C reaches 175 °C while the parison adheres to the cavity. Further, it can be seen from Table 2-21 that the deformation of the moulded article emerges and therefore the paint film appearance of the moulded article becomes inferior if Z°C, which indicates the cavity surface temperature at the time when a mould opening process is started for taking out the moulded article for automotive exterior panel, exceeds 100 °C. Example Temperature of Cavity Content of Filler Sanding Time Moulding Time Evaluation Z Y % Minute Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film 23-1 70 125 0 40 230 NONE NONE NONE NONE NONE 6.0 50 NONE 23-2 70 125 1 40 230 NONE NONE NONE NONE NONE 6.0 52 NONE 23-3 70 125 2 39 230 NONE NONE NONE NONE NONE 6.0 53 NONE 23-4 70 125 3 26 230 NONE NONE NONE NONE NONE 6.1 49 NONE 23-5 70 125 5 20 230 NONE NONE NONE NONE NONE 6.2 50 NONE 23-6 70 125 30 15 230 NONE NONE NONE NONE NONE 6.2 50 NONE 23-7 70 125 35 15 230 NONE NONE NONE NONE NONE 6.3 49 NONE 23-8 70 125 40 10 230 NONE NONE NONE NONE NONE 6.4 51 YES 23-9 70 125 50 - - - - - - - - - - In Table 2-23, if the filler content exceeds 40% by weight, elongation of the parison becomes inferior and therefore rough surface is generated in the surface. As a result, the paint film appearance of the moulded article becomes inferior. The elongation of Sample 9 whose filler content was 50% by weight was so poor that Sample 9 could not be moulded because holes were formed in the article during the moulding operation. Based on these results it can be seen that, if the filler content exceeds 35% by weight, elongation of the parison becomes extremely inferior and therefore the paint film appearance of the moulded article becomes inferior because of the inferior surface condition of the moulded article. To the contrary, it can be seen that, if the filler content is less than 3% by weight, the time required for sanding the parting lines is as long as about 40 minutes. Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 24-1 70 110 210 NONE YES NONE YES YES 10.8 166 YES Example 24-2 70 115 210 NONE SOME NONE SOME SOME 7.4 134 SOME Example 24-3 70 120 230 NONE NONE NONE NONE NONE 6.6 59 NONE Example 24-4 70 130 230 NONE NONE NONE NONE NONE 5.5 30 NONE Example 24-5 70 140 250 NONE NONE NONE NONE NONE 4.6 24 NONE Example 24-6 70 150 250 NONE NONE NONE NONE NONE 2.1 12 NONE Example 24-7 70 160 270 NONE NONE NONE NONE NONE 2.1 10 NONE Exampje 24-8 70 170 270 NONE NONE NONE NONE NONE 2.2 11 NONE Exampje 24-9 70 175 280 NONE NONE NONE NONE NONE 2.1 11 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 25-1 70 110 210 NONE YES NONE YES YES 10.6 169 YES Example 25-2 70 115 210 NONE SOME NONE SOME SOME 7.6 136 SOME Example 25-3 70 120 230 NONE NONE NONE NONE NONE 6.5 59 NONE Example 25- 4 70 130 230 NONE NONE NONE NONE NONE 5.4 42 NONE Example 25-5 70 140 250 NONE NONE NONE NONE NONE 2.8 28 NONE Example 25-6 70 150 250 NONE NONE NONE NONE NONE 1.2 10 NONE Example 25-7 70 160 270 NONE NONE NONE NONE NONE 0.9 11 NONE Example 25-8 70 170 270 NONE NONE NONE NONE NONE 1.0 10 NONE Example 25-9 70 175 280 NONE NONE NONE NONE NONE 1.1 11 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 26-1 70 110 210 NONE YES NONE YES YES 11.8 165 YES Example 26-2 70 115 210 NONE SOME NONE SOME SOME 7.4 144 SOME Example 26-3 70 120 230 NONE NONE NONE NONE NONE 6.0 61 NONE Example 26-4 70 130 230 NONE NONE NONE NONE NONE 5.5 40 NONE Example 26-5 70 140 250 NONE NONE NONE NONE NONE 2.4 27 NONE Example 26-6 70 150 250 NONE NONE NONE NONE NONE 1.2 14 NONE Example 26-7 70 160 270 NONE NONE SOME NONE NONE 1.1 11 SOME Example 26-8 70 170 270 NONE NONE SOME NONE NONE 1.1 11 SOME Example 26-9 70 175 280 NONE NONE SOME NONE NONE 1.1 10 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 27-1 70 110 210 NONE YES NONE YES YES 12.0 184 YES Example 27-2 70 115 210 NONE SOME NONE SOME SOME 7.8 132 SOME Example 27-3 70 120 230 NONE NONE SOME NONE NONE 6.1 59 SOME Example 27-4 70 130 230 NONE NONE SOME NONE NONE 5.4 40 SOME Example 27-5 70 140 250 NONE NONE SOME NONE NONE 2.3 24 SOME Example 27-6 70 150 250 NONE NONE YES NONE NONE 1.2 12 YES Example 27-7 70 160 270 NONE NONE YES NONE NONE 0.9 10 YES Example 27-8 70 170 270 NONE NONE YES NONE NONE 0.8 11 YES Example 27-9 70 170 280 NONE NONE YES NONE NONE 0.8 11 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 28-1 70 110 210 NONE YES NONE YES YES 11.8 175 YES Example 28-2 70 115 210 NONE SOME NONE SOME SOME 8.0 120 YES Example 28-3 70 120 230 NONE SOME NONE NONE NONE 7.4 66 YES Example 28-4 70 130 230 NONE SOME NONE NONE NONE 8.4 35 SOME Example 28-5 70 140 250 NONE NONE NONE NONE NONE 9.3 29 NONE Example 28-6 70 150 250 NONE NONE NONE NONE NONE 9.0 30 NONE Example 28-7 70 160 270 NONE NONE SOME NONE NONE 9.1 31 NONE Example 28-8 70 170 270 NONE NONE SOME NONE NONE 8.9 31 NONE Example 28-9 70 175 280 NONE NONE SOME NONE NONE 8.9 31 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 29-1 70 110 210 NONE YES NONE YES YES 12.0 189 YES Example 29-2 70 115 210 NONE SOME NONE SOME SOME 8.4 119 YES Example 29-3 70 120 230 NONE SOME NONE NONE NONE 8.6 61 YES Example 29-4 70 130 230 NONE SOME NONE NONE NONE 9.8 40 SOME Example 29-5 70 140 250 NONE NONE NONE NONE NONE 10.2 35 NONE Example 29-6 70 150 250 NONE NONE NONE NONE NONE 10.1 30 NONE Example 29-7 70 160 270 NONE NONE SOME NONE NONE 10.1 30 SOME Example 29-8 70 170 270 NONE NONE SOME NONE NONE 10.2 30 NONE Example 29-9 70 175 280 NONE NONE SOME NONE NONE 10.2 30 NONE It can be seen from Tables 2-24 ∼ Tables 2-29 that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 µm. Samples in Table 2-27 have extremely poor paint film appearance. Also, samples in Table 2-29 have poor paint film appearance. Based on these results, it can be seen that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 µm. Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 30-1 70 110 210 NONE YES NONE YES YES 12.2 186 YES Exampje 30-2 70 115 210 NONE SOME NONE SOME SOME 7.8 119 SOME Example 30-3 70 120 230 NONE NONE NONE NONE NONE 6.9 70 NONE Example 30-4 70 130 230 NONE NONE NONE NONE NONE 5.2 42 NONE Example 30-5 70 140 250 NONE NONE NONE NONE NONE 3.4 24 NONE Example 30-6 70 150 250 NONE NONE NONE NONE NONE 3.2 11.0 NONE Example 30-7 70 160 270 NONE NONE NONE NONE NONE 3.0 10.0 NONE Example 30-8 70 170 270 NONE NONE NONE NONE NONE 3.1 10.2 NONE Example 30-9 70 175 280 NONE NONE NONE NONE NONE 3.1 10.2 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 31-1 70 110 210 NONE YES NONE YES YES 12.4 180 YES Example 31-2 70 115 210 NONE SOME NONE SOME SOME 8.7 140 SOME Example 31-3 70 120 230 NONE NONE SOME NONE NONE 7.0 98 SOME Example 31-4 70 130 230 NONE NONE SOME NONE NONE 5.8 38 SOME Example 31-5 70 140 250 NONE NONE SOME NONE NONE 3.7 12 SOME Example 31-6 70 150 250 NONE NONE YES NONE NONE 3.2 8.9 YES Example 31-7 70 160 270 NONE NONE YES NONE NONE 2.9 8.9 YES Example 31-8 70 170 270 NONE NONE YES NONE NONE 2.9 9.0 YES Example 31-9 70 175 280 NONE NONE YES NONE NONE 2.9 9.1 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 32-1 70 110 210 NONE YES NONE YES YES 12.6 198 YES Example 32-2 70 115 210 NONE SOME NONE NONE NONE 7.8 160 SOME Example 32-3 70 120 230 NONE SOME NONE NONE NONE 6.4 155 SOME Example 32-4 70 130 230 NONE SOME NONE NONE NONE 5.5 149 SOME Example 32-5 70 140 250 NONE NONE NONE NONE NONE 4.9 150 NONE Example 32-6 70 150 250 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-7 70 160 270 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-8 70 170 270 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-9 70 175 280 NONE NONE NONE NONE NONE 5.0 152 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 33-1 70 110 210 NONE YES NONE YES YES 12.6 202 YES Example 33-2 70 115 210 NONE SOME NONE NONE NONE 7.9 184 SOME Example 33-3 70 120 230 NONE SOME NONE NONE NONE 6.5 162 SOME Example 33-4 70 130 230 NONE SOME NONE NONE NONE 5.5 160 SOME Example 33-5 70 140 250 NONE SOME NONE NONE NONE 4.8 160 SOME Example 33-6 70 150 250 NONE NONE NONE NONE NONE 5.0 160 SOME Example 33-7 70 160 270 NONE NONE NONE NONE NONE 5.1 160 SOME Example 33-8 70 170 270 NONE NONE NONE NONE NONE 5.1 159 SOME Example 33-9 70 175 280 NONE NONE NONE NONE NONE 5.1 161 SOME It can be seen from Tables 2-30 - Tables 2-33 that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 µm. Samples in Table 2-31 have extremely poor paint film appearance. Also, samples in Table 2-33 have poor paint film appearance. Based on these results, it can be seen that the average peak-to-peak distance of the minute concavities/convexities of cavity needs to be 10 to 150 µm. It can be seen from Tables 2-16 - Tables 2-33 that the moulded article for automotive exterior panel needs to have surface irregularities comprising a surface roughness Rt of 0.9 to 9.0 µm and an average peak-to-peak distance Sm of 10 to 150 µm. Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 34-1 70 110 210 NONE YES NONE YES YES 12.6 202 YES Example 34-2 70 115 210 NONE SOME NONE YES YES 12.4 120 YES Example 34-3 70 120 230 NONE SOME NONE NONE NONE 6.4 58 NONE Example 34-4 70 125 230 NONE SOME NONE NONE NONE 5.8 38 SOME Example 34-5 70 130 250 NONE SOME NONE NONE NONE 5.0 25 NONE Example 34-6 70 140 250 NONE NONE NONE NONE NONE 5.0 25 NONE Example 34-7 70 150 270 NONE NONE NONE NONE NONE 5.0 26 NONE Example 34-8 70 160 270 NONE NONE NONE NONE NONE 5.1 24 NONE Example 34-9 70 165 300 NONE NONE NONE NONE NONE 5.0 25 NONE Example Temperature Of Cavity Content of Filler Sanding Time Moulding Time Evaluation Z Y % Minute Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film 35-1 70 125 0 50 230 NONE NONE NONE NONE NONE 6.4 38 NONE 35-2 70 125 1 50 230 NONE NONE NONE NONE NONE 6.4 37 NONE 35-3 70 125 2 47 230 NONE NONE NONE NONE NONE 6.4 38 NONE 35-4 70 125 3 36 230 NONE SOME NONE NONE NONE 6.4 38 NONE 35-5 70 125 5 30 230 NONE SOME NONE NONE NONE 6.3 40 NONE 35-6 70 125 30 25 230 NONE NONE NONE NONE NONE 6.5 39 NONE 35-7 70 125 35 20 230 NONE NONE NONE NONE NONE 6.6 38 NONE 35-8 70 125 40 20 230 NONE YES NONE NONE NONE 6.6 38 YES 35-9 70 125 50 - - - - - - - - - - In Table 2-35, if the filler content exceeds 40% by weight, elongation of the parison becomes inferior and therefore rough surface emerges in the surface. As a result, the paint film appearance of the moulded article becomes inferior. The elongation of Sample 9 whose filler content was 50% by weight was so poor that Sample 9 could not be moulded because holes were formed in the article during the moulding operation. Based on these results, it can be seen that, if the filler content exceeds 35% by weight, elongation of the parison becomes extremely inferior and therefore the paint film appearance of the moulded article becomes inferior because of the inferior surface condition of the moulded article. To the contrary, it can be seen that, if the filler content is less than 3% by weight, the time required for sanding the parting lines is as long as about 50 minutes. Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 36-1 70 110 210 NONE YES NONE YES YES 12.3 195 YES Example 36-2 70 115 210 NONE SOME NONE YES YES 11.0 140 YES Example 36-3 70 120 230 NONE NONE NONE NONE NONE 6.8 48 NONE Example 36-4 70 125 230 NONE NONE NONE NONE NONE 4.9 18 NONE Example 36-5 70 130 250 NONE NONE NONE NONE NONE 2.0 11 NONE Example 36-6 70 140 250 NONE NONE NONE NONE NONE 2.0 11 NONE Example 36-7 70 150 270 NONE NONE NONE NONE NONE 2.1 11 NONE Example 36-8 70 160 270 NONE NONE NONE NONE NONE 2.1 11 NONE Example 36-9 70 165 300 NONE NONE NONE NONE NONE 2.0 11 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 37-1 70 110 210 NONE YES NONE YES YES 12.4 204 YES Example 37-2 70 115 210 NONE SOME NONE YES SOME 11.2 135 YES Example 37-3 70 120 230 NONE NONE NONE NONE NONE 6.5 52 NONE Example 37-4 70 125 230 NONE NONE NONE NONE NONE 4.2 20 NONE Example 37-5 70 130 250 NONE NONE NONE NONE NONE 1.4 12 NONE Example 37-6 70 140 250 NONE NONE NONE NONE NONE 1.1 11 NONE Example 37-7 70 150 270 NONE NONE NONE NONE NONE 1.0 11 NONE Example 37-8 70 160 270 NONE NONE NONE NONE NONE 1.1 10 NONE Example 37-9 70 165 300 NONE NONE NONE NONE NONE 1.0 10 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 38-1 70 110 210 NONE YES NONE YES YES 12.4 203 YES Example 38-2 70 115 210 NONE SOME NONE YES YES 11.6 130 YES Example 38-3 70 120 230 NONE NONE NONE NONE NONE 6.2 58 NONE Example 38-4 70 125 230 NONE NONE NONE NONE NONE 4.3 24 NONE Example 38-5 70 130 250 NONE NONE NONE NONE NONE 1.3 14 NONE Example 38-6 70 140 250 NONE NONE NONE NONE NONE 0.9 10 NONE Example 38-7 70 150 270 NONE NONE NONE NONE NONE 0.9 11 NONE Example 38-8 70 160 270 NONE NONE SOME NONE NONE 1.0 10 SOME Example 38-9 70 165 300 NONE NONE SOME NONE NONE 0.9 10 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 39-1 70 110 210 NONE YES NONE YES YES 12.8 195 YES Example 39-2 70 115 210 NONE YES SOME YES YES 11.4 138 YES Example 39-3 70 120 230 NONE NONE SOME NONE NONE 6.8 64 SOME Example 39-4 70 125 230 NONE NONE YES NONE NONE 4.6 28 YES Example 39-5 70 130 250 NONE NONE YES NONE NONE 1.2 14 YES Example 39-6 70 140 250 NONE NONE YES NONE NONE 0.8 10 YES Example 39-7 70 150 270 NONE NONE YES NONE NONE 0.7 9 YES Example 39-8 70 160 270 NONE NONE YES NONE NONE 0.8 9 YES Example 39-9 70 165 300 NONE NONE SOME NONE NONE 0.8 10 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Examplc 40-1 70 110 210 NONE YES NONE YES YES 12.6 201 YES Example 40-2 70 115 210 NONE SOME NONE YES SOME 11.9 124 YES Example 40-3 70 120 230 NONE NONE NONE NONE NONE 9.7 68 NONE Example 40-4 70 125 230 NONE NONE NONE NONE NONE 9.6 38 NONE Example 40-5 70 130 250 NONE NONE NONE NONE NONE 9.4 27 NONE Example 40-6 70 140 250 NONE NONE NONE NONE NONE 9.0 25 NONE Example 40-7 70 150 270 NONE NONE NONE NONE NONE 8.9 24 NONE Example 40-8 70 160 270 NONE NONE NONE NONE NONE 9.0 24 NONE Example 40-9 70 165 300 NONE NONE NONE NONE NONE 9.0 25 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 41-1 70 110 210 NONE YES NONE YES YES 12.3 204 YES Example 41-2 70 115 210 NONE YES NONE YES SOME 11.3 134 YES Example 41-3 70 120 230 NONE SOME NONE NONE NONE 11.4 64 YES Example 41-4 70 125 230 NONE SOME NONE NONE NONE 10.9 39 SOME Example 41-5 70 130 250 NONE SOME NONE NONE NONE 10.2 28 SOME Example 41-6 70 140 250 NONE SOME NONE NONE NONE 10.2 25 SOME Example 41-7 70 150 270 NONE NONE NONE NONE NONE 10.0 25 SOME Example 41-8 70 160 270 NONE NONE NONE NONE NONE 10.1 25 SOME Example 41-9 70 165 300 NONE NONE NONE NONE NONE 10.1 25 SOME It can be seen from Tables 2-36 - Tables 2-41 that the moulding time rises to 300 seconds if the cavity surface temperature Y°C reaches 165 °C while the parison adheres to the cavity. It can be seen from Tables 2-36 - Tables 2-41 that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 µm. Samples in Table 2-39 have extremely poor paint film appearance. Also, samples in Table 2-40 have poor paint film appearance. Based on these results, it can be seen that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 µm. Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 42-1 70 110 210 NONE YES NONE YES YES 12.8 198 YES Example 42-2 70 115 210 NONE YES NONE YES YES 12.0 148 YES Example 42-3 70 120 230 NONE SOME SOME NONE NONE 7.0 59 SOME Example 42-4 70 125 230 NONE NONE SOME NONE NONE 5.1 28 SOME Example 42-5 70 130 250 NONE SOME YES NONE NONE 3.1 12 YES Exampe 42-6 70 140 250 NONE SOME YES NONE NONE 2.1 9 YES Example 42-7 70 150 270 NONE NONE YES NONE NONE 2.0 9 YES Example 42-8 70 160 270 NONE NONE YES NONE NONE 2.0 8 YES Example 42-9 70 165 300 NONE NONE YES NONE NONE 2.0 8 YES Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 43-1 70 110 210 NONE YES NONE YES YES 13.3 208 YES Example 43-2 70 115 210 NONE SOME NONE YES YES 13.0 158 YES Example 43-3 70 120 230 NONE NONE NONE NONE NONE 8.0 69 NONE Example 43-4 70 125 230 NONE NONE NONE NONE NONE 6.1 38 NONE Example 43-5 70 130 250 NONE NONE NONE NONE NONE 4.1 22 NONE Exampje 43-6 70 140 250 NONE NONE NONE NONE NONE 3.1 12 NONE Example 43-7 70 150 270 NONE NONE NONE NONE NONE 3.1 11 NONE Example 43-8 70 160 270 NONE NONE NONE NONE NONE 3.1 11 NONE Example 43-9 70 165 300 NONE NONE NONE NONE NONE 3.1 12 NONE Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 44-1 70 110 210 NONE YES NONE YES YES 12.4 199 YES Example44-2 70 115 210 NONE YES NONE YES YES 11.8 155 YES Example 44-3 70 120 230 NONE SOME NONE NONE NONE 6.4 148 SOME Example 44-4 70 125 230 NONE NONE NONE NONE NONE 5.7 150 SOME Example 44-5 70 130 250 NONE NONE NONE NONE NONE 5.2 150 NONE Example 44-6 70 140 250 NONE NONE NONE NONE NONE 5.0 148 NONE Example 44-7 70 150 270 NONE NONE NONE NONE NONE 5.0 149 SOME Example 44-8 70 165 270 NONE NONE NONE NONE NONE 5.0 148 SOME Example 44-9 70 165 300 NONE NONE NONE NONE NONE 5.0 148 SOME Example Temperature of Cavity Moulding Time Evaluation Z Y Second Deformation Surface Condition Air Mark Die Line Bit Rt Sm Appearance of Paint Film Example 45-1 70 110 210 NONE YES NONE YES YES 11.9 210 YES Example 45-2 70 115 210 NONE YES NONE YES YES 11.8 184 YES Example 45-3 70 120 230 NONE SOME NONE NONE NONE 6.2 165 SOME Example 45-4 70 125 230 NONE SOME NONE NONE NONE 5.4 162 SOME Example 45-5 70 130 250 NONE NONE NONE NONE NONE 5.2 164 SOME Example 45-6 70 140 250 NONE NONE NONE NONE NONE 5.1 162 SOME Example 45-7 70 150 270 NONE NONE NONE NONE NONE 5.1 162 YES Example 45-8 70 160 270 NONE NONE NONE NONE NONE 5.1 161 YES Example 45-9 70 165 300 NONE NONE NONE NONE NONE 5.0 159 YES It can be seen from Tables 2-42 - Tables 2-45 that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 µm. Samples in Table 2-42 have extremely poor paint film appearance. Also, samples in Table 2-45 have poor paint film appearance. Based on these results, it can be seen that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 µm. It can be seen from Tables 2-34 - Tables 2-45 that the moulded article for automotive exterior panel needs to have surface irregularities comprising a surface roughness Rt of 0.9 to 9.0 µm and an average peak-to-peak distance Sm of 10 to 150 µm. The objects and advantages of the present invention may be further realized and attained by means of the instrumentalities and combinations pointed out in the appended claims. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.

Claims: An automotive exterior panel with a smooth surface comprising: a blow moulded article of a non-crystalline resin exhibiting a tensile modulus of 2000 Kg/cm 2 at 75°C or above, wherein said blow moulded article directly after blow moulding has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 µm and an average peak-to-peak distance in the range of from 10 to 150 µm, and wherein said panel has a 15 to 150 µm thick paint film. An automotive exterior panel with a smooth appearance comprising: a blow moulded article of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm 2 or more at 23°C, wherein said blow moulded article has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 µm and an average peak-to-peak distance in the range of from 10 to 150 µm, and wherein said panel has a 15 to 150 µm thick paint film. An automotive exterior panel according to Claim 2, wherein said crystalline resin comprises 3% to 35% by weight of an inorganic filler. An automotive exterior panel according to Claim 2 or 3, wherein said crystalline resin is polypropylene. A method for producing an automotive exterior panel, comprising the steps of: disposing a parison, which is composed of a non-crystalline resin exhibiting a tensile modulus of 2000 Kg/cm 2 at 75°C or above, between mould halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 µm and the average peak-to-peak distance is in the range of from 10 to 150 µm: closing said mould halves to from a cavity; adhering said parson to said mould halves by introducing thereinto a pressurized air to said cavity whose surface temperature is set to Y°C which falls in a range of Y = (0.96 X + 3) to Y = (0.96 X + 40), where X is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 ; opening said mould halves and removing said hollow moulded article; and painting an external face of said hollow moulded article with a 15 to 150 µm thick paint film. A method for producing an automotive exterior panel according to Claim 5, further comprising the step of setting a cavity surface temperature Z°C at which a mould opening process is completed for taking out said moulded article, to a temperature in the range of Z≤0.9X where X is a temperature at which the tensile modulus of the non-crystalline resin is 2000 Kg/cm 2 . A method of producing an automotive exterior panel, comprising: disposing a parison between mould halves; heating the mould halves; closing the mould; introducing pressurised gas into the parison to adhere the parison to the mould surface; opening the mould to remove the hollow moulded article; and painting an external face of said hollow moulded article; characterised by : a) forming the parison from a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm 2 or more at 23°C; b) providing mould halves having mould surfaces with minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 µm and the average peak-to-peak distance is in the range of from 10 to 150 µm; and c) raising the surface temperature of the of the mould surfaces to a temperature Y°C which falls in the range of A < Y < 1.07B, where A is a peak crystallisation temperature (°C) in a DSC curve of the crystalline resin and B is a peak fusion temperature (°C) in a DSC curve of the crystalline resin, either before the mould is closed or during adhesion of the parison; and d) painting the external face of said hollow moulded article with a 15 to 150 µm thick paint film. A method according to Claim 7, wherein said crystalline resin comprises 3% to 35% by weight of an inorganic filler. A method according to Claim 7 or 8, further comprising the step of setting a cavity surface temperature (Z°C) at which a mould opening process is started for taking out said moulded article to a temperature in the range of Z ≤ A -15.

Inventors: KODAIRA TOORU, MATSUBA AKIHIKO, SUMI TAKEHIKO, TAMADA TERUO, KODAIRA, TOORU, MATSUBA, AKIHIKO, SUMI, TAKEHIKO, TAMADA, TERUO
Applicants: KYORAKU CO LTD, KYORAKU CO.,LTD.
Application year: 2000
Main classification: B29C49
IPC codes: B29C49