How to manufacture polypropylene sheets.

Abstract

DEPCT64 A method for producing polypropylene sheets with a thickness of 0.5 to 5 mm, including an assembly method; Step 1 of precursor preparation in the location of the first biaxially drawn polypropylene film. And then there are polypropylene films with a thickness of less than 0.15 mm and a melting point Tmh, which are biaxially tensile types. The second time, the thickness was less than 0.15 mm, and the melting point of the Tml was alternately stacked; Step 2 involves bringing the heating element into contact with the outermost layer of the precursor to seal it. A layer of film with heat on which Tmh-Tml is greater than or equal to 8 (degrees Celsius). Where the melting point is measured by a differential scanning calorimeter (DSC) under certain conditions. The temperature ranges from 30°C to 230°C, and the heating rate is 10°C / minute. -----------------------------------------------------------

Description

Manufacturing method of polypropylene sheets

[0001] This invention relates to a method for manufacturing polypropylene sheets.

[0002] Polypropylene stretched films are used in fields requiring high heat resistance, as well as excellent transparency and mechanical properties. However, their thinness (less than 150 μm) limits their applications, and increasing the thickness of the stretched film is expected to expand its uses to other applications. For example, Patent Document 1 discloses that a sheet with a certain thickness or more can be manufactured by laminating and heat-fusing multiple uniaxially stretched polypropylene films. Furthermore, Patent Document 2 discloses that a polypropylene sheet with excellent transparency and mechanical properties can be provided by laminating and heat-fusing multiple biaxially stretched polypropylene films having specific higher-order structural parameters.

[0003] Japanese Patent Publication No. 2012-96526 Japanese Patent Publication No. 2017-186561

[0004] However, when attempting to manufacture the sheets described in the aforementioned patent document at high speed to achieve high productivity, a problem arose in that the heat fusion between uniaxially oriented polypropylene films or biaxially oriented polypropylene films was insufficient. Therefore, there is a demand to apply polypropylene sheets to fields requiring higher mechanical properties. In view of these circumstances, the present invention aims to provide a manufacturing method for producing polypropylene sheets with excellent transparency and mechanical properties at high productivity.

[0005] The inventors have found that the above problem can be solved by alternately laminating biaxially oriented polypropylene films having specific melting points and heat-fusing the interlayers of the films, and have completed the present invention. That is, the above problem is solved by the present invention as follows: [1] A method for manufacturing a polypropylene sheet having a thickness of 0.5 to 5 mm, comprising: step 1 of preparing a precursor in which a first biaxially oriented polypropylene film having a thickness of less than 0.15 mm and a melting point Tmh and a second biaxially oriented polypropylene film having a thickness of less than 0.15 mm and a melting point Tml are alternately laminated; and step 2 of contacting the outermost layer of the precursor with a heating element to heat-fuse the interlayers of the films, wherein Tmh - Tml ≥ 8 (°C), (however, these melting points are obtained by measuring them using DSC at a heating rate of 10°C / min from 30°C to 230°C). [2] Melting point Tm of the outermost layer ｏｕｔ The temperature T of the heating element satisfies the following conditions: Tm ｏｕｔ -T≧4(°C) The method for manufacturing the sheet as described in [1]. [3] The method for manufacturing the sheet as described in [1] or [2], wherein step 2 is carried out using a heating roll as a heating element. [4] The method for manufacturing the sheet as described in any of [1] to [3], wherein the ratio Dh / Dl of the thickness of the layer due to the first biaxially oriented polypropylene film to the thickness of the layer due to the second biaxially oriented polypropylene film in the polypropylene sheet is 1 to 30. [5] The integral intensity at the azimuthal angle I obtained from the two-dimensional profile of small-angle X-ray scattering obtained by incidenting X-rays (wavelength: 0.154 nm) in the X direction of the polypropylene sheet. Ｘ Ｖ A manufacturing method according to any one of [1] to [4], wherein a scattering peak is observed in the range of 2θ = 0.2° to 1.0°. [6] A manufacturing method according to any one of [1] to [5], wherein step 1 includes a step of co-extruding the raw material for the first biaxially oriented polypropylene film and the raw material for the second biaxially oriented polypropylene film to prepare a raw material sheet having a plurality of layers, and biaxially stretching the same to prepare the precursor. [7] A manufacturing method for a molded article, comprising preparing a polypropylene sheet by the method according to any one of [1] to [6] and molding the same.

[0006] The present invention can provide a manufacturing method for producing a polypropylene sheet having excellent transparency and mechanical properties with high productivity.

[0007] It is a diagram for explaining the cross-sectional structure of a sheet obtained by laminating and heat-sealing biaxially stretched polypropylene films. Integrated intensity I at azimuthal angle Ｘ Ｖ and I Ｘ Ｌ It is a diagram for explaining the measurement method of. Integrated intensity I at azimuthal angle Ｘ Ｖ and I Ｘ Ｌ It is a diagram for explaining the analysis method of. Integrated intensity I at azimuthal angle of the small-angle X-ray scattering two-dimensional profile in Example 10 and Comparative Example 8 Ｘ Ｌ (corresponding to the equatorial (Y) direction and normalized per pixel) and the relationship with 2θ. Integrated intensity I at azimuthal angle of the small-angle X-ray scattering two-dimensional profile in Example 10 and Comparative Example 8 Ｘ Ｖ (corresponding to the meridian (Z) direction and normalized per pixel) and the relationship with 2θ.

[0008] Hereinafter, the present invention will be described in detail. In the present invention, "X to Y" includes its end values, that is, X and Y. In the present invention, a sheet means a film-like member having a thickness of 150 μm or more, and a film means a film-like member having a thickness of less than 150 μm.

[0009] 1. Manufacturing Method The manufacturing method for the sheet of the present invention includes a step 1 of preparing a precursor in which a first biaxially oriented polypropylene film having a thickness of less than 0.15 mm and a melting point Tmh and a second biaxially oriented polypropylene film having a thickness of less than 0.15 mm and a melting point Tml are alternately laminated, and a step 2 of contacting the outermost layer of the precursor with a heating element to heat-fuse the interlayers of the films. The melting points satisfy Tmh - Tml ≥ 8 (°C). Good interlayer adhesion is achieved when the melting point difference is within this range. From this viewpoint, the melting point difference is preferably 10 (°C) or more. There is no upper limit to the melting point difference, but from the viewpoint of polypropylene manufacturing, it is preferably 40 (°C) or less. The following describes each step.

[0010] (1) Step 1 In this step, a precursor is prepared in which a first biaxially oriented polypropylene film and a second biaxially oriented polypropylene film are alternately laminated. Since the precursor contains multiple of the films, there are multiple interlayers. Not all of these interlayers need to be fused, but one or more interlayers may be fused. For example, when one sheet each of the first biaxially oriented polypropylene film and the second biaxially oriented polypropylene film are laminated, it is preferable that all interlayers in the precursor are not fused. Also, as will be described later, when a co-extruded film of the first biaxially oriented polypropylene film and the second biaxially oriented polypropylene film is used, one or more interlayers in the precursor are fused.

[0011] This process can be carried out by separately preparing a first biaxially oriented polypropylene film (hereinafter also referred to as "F1" for convenience) and a second biaxially oriented polypropylene film (hereinafter also referred to as "F2" for convenience) and laminating them alternately. For example, a precursor can be prepared by laminating them in the order F1 / F2 / F1 / F2 / F1. In this case, it is preferable that one or some of the layers are not fused together. From the viewpoint of improving the heat resistance of the resulting sheet, it is preferable that both outermost layers are F1.

[0012] A biaxially stretched film having a thickness of less than 0.15 mm can be obtained by biaxially stretching a composition containing polypropylene or the polypropylene and an additive in a known method. For example, the polypropylene or the like can be extruded or press-molded to obtain an unstretched sheet, and the sheet can be biaxially stretched to obtain a biaxially stretched film. The thickness of the film is not limited as long as it is less than 0.15 mm, but is preferably 0.12 mm or less, more preferably 0.10 mm or less, from the viewpoint of ease of handling and the like. The lower limit of the thickness is not limited, but is preferably 0.01 mm or more, more preferably 0.03 mm or more.

[0013] This step can also be carried out using a co-extruded film of F1 and F2. By doing so, step 2 can be simplified. Specifically, the raw materials of F1 and the raw materials of F2 are co-extruded to prepare a base sheet having a plurality of layers, and this is biaxially stretched to prepare a precursor in which F1 and F2 are alternately laminated. In this case, the number of layers of the precursor is not limited, but 2 layers or 3 layers are preferable. For example, a co-extruded two-layer biaxially stretched film of F1 / F2 or a co-extruded three-layer biaxially stretched film of F2 / F1 / F2 can be obtained, and the desired number of such films can be stacked. As an example, if a two-layer base sheet of F1 / F2 is denoted as [F1 / F2], the following precursors can be prepared. [F1 / F2] / [F1 / F2] / [F1 / F2] / F1 In the precursor, the layers between the co-extruded film and other co-extruded films and the layers between the co-extruded film and other single-layer films are not fused. The raw material of F1 is a material that can form F1, and can be in any shape of film, sheet, pellet, or powder. The same applies to the raw material of F2. The precursor may include a case where F1 and F1 or F2 and F2 are integrated by heat fusion in step 2 described later, and finally have a structure in which F1 and F2 are alternately laminated. For example, the following precursors may be prepared. F1 / [F2 / F1 / F2] / [F2 / F1 / F2] / F1

[0014] Each film can be placed in an arbitrary direction. By the way of placing the film, the orientation direction in the sheet plane can be adjusted. As described above, the number of films to be laminated is adjusted as appropriate. Details of the polypropylene and the additive will be described later.

[0015] (2) Step 2: In this step, a heating body is brought into contact with the outermost layer of the precursor to heat-seal between the layers. The melting point Tm of the outermost layer ｏｕｔ and the temperature T of the heating body preferably satisfy the relationship Tm ｏｕｔ - T ≥ 4 (°C). By satisfying this relationship, good heat-sealing between the layers can be achieved. From this perspective, it is more preferable that the temperature difference is 6 °C or more. The upper limit of the temperature difference is not limited, but from the perspective of polypropylene production, it is preferably 40 °C or less. T can be measured by any method, but it is preferable to measure it using a non-contact thermometer such as an infrared thermometer. Tm ｏｕｔ corresponds to the melting point of the single-layer film disposed on the outermost layer. The melting point is defined as the peak temperature of the melting curve obtained by measuring with a heating rate of 10 °C / min from 30 °C to 230 °C by DSC. The temperature of the heating body is not limited, but is preferably about 120 to 190 °C, more preferably 140 to 170 °C, and even more preferably 150 to 165 °C.

[0016] This step is preferably continuously performed using a heating roll as the heating body. Specifically, the precursor is passed between two heated rolls to heat-seal between the layers. Two rolls are taken as a set, and a heating roll formed by combining two or more sets of rolls may be used as the heating body for heat-sealing. The pressure applied at this time is adjusted as appropriate. The take-up speed in this roll forming is not limited, but is preferably about 0.05 to 10 m / min.

[0017] As methods other than roll forming, pressure welding and heat-sealing are mentioned. Further, when heat-sealing the film, it is preferable to apply pressure to suppress heat shrinkage and further promote orientation. The pressure at that time is adjusted according to the heat-sealing temperature.

[0018] (3) Other steps: The manufacturing method of the present invention may further include known steps such as cooling the sheet obtained in the previous step. The cooling method is not limited, but examples include allowing it to cool at room temperature, or cold pressing at room temperature or at 10 to 20 °C.

[0019] The sheets obtained by the manufacturing method of the present invention exhibit good adhesion between films and virtually no discontinuities between layers. Therefore, they can be handled as a single, integrated sheet. While conventional methods made it industrially impractical to obtain biaxially oriented sheets with a thickness of 0.5 mm or more from a cost perspective, the present invention makes it possible to industrially manufacture sheets with a thickness of 0.5 mm or more and orientation in two or more directions.

[0020] Various molded articles can be obtained by secondary molding (including shaping into a desired form) of the sheet obtained by the manufacturing method of the present invention using a method appropriate to the purpose. Examples of secondary molding methods include known press molding, hot plate molding, stretch molding, rolling molding, deep drawing molding, pressure welding molding, fusion molding, vacuum molding, pressure molding, and vacuum pressure molding. Furthermore, a special film may be attached to the outermost surface of the sheet obtained by the manufacturing method of the present invention for purposes such as decorative properties or surface modification. Examples of films to be attached include anti-fog films, low-temperature sealing films, adhesive films, printed films, embossed films, and retort films. There are no particular restrictions on the thickness of the outermost film, but if it is too thick, it may impair the properties of the sheet obtained by the present invention, and special films are generally expensive and undesirable from an economic standpoint, so a thin film is preferable. In the process of heat-fusion lamination of biaxially oriented polypropylene films, a special film can be laminated on the surface of the film arranged in the outermost layer.

[0021] In addition, the sheet obtained by the manufacturing method of the present invention can be painted to create a painted sheet having a coating on it. The type of coating is not limited and is not limited as long as it is commonly used in the painting field. However, in the present invention, coatings used for car body painting are preferred. Preferred coatings include epoxy coatings, urethane coatings, polyester coatings, etc. If necessary, an undercoat (primer coating), an intermediate coating, and an upper coating (clear coating) may be provided. When the sheet obtained by the manufacturing method of the present invention is used as a sheet for coating (coated sheet), it is preferable that the surface to be painted has functional groups.

[0022] (4) Imparting of Functional Groups The method for imparting functional groups to the surface of the sheet obtained by the manufacturing method of the present invention is not limited. For example, oxygen-containing functional groups can be imparted to the surface of the sheet obtained by the manufacturing method of the present invention by subjecting it to plasma treatment or corona treatment. Alternatively, functional groups can be imparted by preparing a polypropylene film having functional groups and laminating it with the aforementioned film in the lamination step such that the functional group-containing film becomes the outermost layer. The latter method will be described here.

[0023] Polypropylene films having oxygen-containing functional groups can be obtained by forming known polypropylenes, such as maleic anhydride-modified polypropylene or epoxy-modified polypropylene, into a film. The thickness of the functional group-containing film is not limited, but is preferably less than 150 μm. The functional group-containing film may or may not be biaxially oriented. In the lamination process, the polypropylene film having functional groups and the polypropylene film without functional groups may be laminated simultaneously, or the polypropylene film without functional groups may be laminated beforehand to produce a sheet, and the polypropylene film having functional groups may be laminated onto the surface of the sheet. However, considering workability, the simultaneous lamination method is preferred.

[0024] 2. Polypropylene Sheet The following describes the polypropylene sheet obtained by the manufacturing method of the present invention. (1) Thickness The polypropylene sheet obtained by the manufacturing method of the present invention (also referred to as "sheet obtained by the manufacturing method of the present invention") has a thickness of 0.5 to 5 mm. The thickness may be adjusted as appropriate depending on the application, for example, it may be 0.7 mm or more or 1 mm or more. The thickness may also be 3 mm or less or 1 mm or less.

[0025] (2) Multilayer structure The sheet obtained by the manufacturing method of the present invention has a multilayer structure in which a first layer having a high melting point Tmh and a second layer having a low melting point Tml are alternately laminated. Since each layer is fused together, the sheet obtained by the manufacturing method of the present invention is an integrated sheet. Specifically, whether each layer of the sheet is fused together and integrated, or whether delamination occurs when slight force is applied due to insufficient fusion, can be confirmed by cross-sectional observation with a polarizing microscope, as shown in Figure 1. Figure 1(1) shows the first layer and the second layer being well fused together. Figure 1(2) shows the interlayers of a sheet consisting of multiple first layers being completely delaminated, partially delaminated, and well fused together.

[0026] Regarding the ratio Dh / Dl, which is the ratio of the thickness Dh of the first layer to the thickness Dl of the second layer, a smaller value results in excellent interlayer bonding, while a larger value results in excellent rigidity of the resulting sheet. Considering the balance between bonding and rigidity, Dh / Dl is preferably 1 to 30, more preferably 1 to 25, and even more preferably 4 to 25.

[0027] The number of layers depends on the thickness of the single-layer film, but in one embodiment, it is preferable that there are a total of about 15 to 100 layers, consisting of a first layer and a second layer, each about 0.01 to 0.1 mm thick. In this case, it is preferable that both outermost layers are first layers having a high melting point.

[0028] These melting points are obtained by measuring them using DSC under conditions of heating rate of 10°C / min from 30°C to 230°C. The ranges of Tmh and Tml are not limited, but in one embodiment, Tmh is preferably 160 to 180°C and Tml is preferably 130 to 150°C.

[0029] In the sheet obtained by the manufacturing method of the present invention, the integrated intensity I at the scattering azimuthal angle in the meridian (Z) direction in the two-dimensional profile of small-angle X-rays measured by incident X-rays (wavelength: 0.154 nm) from the X direction is Ｘ ＶIn this case, it is preferable that a scattering peak is observed in the range of 2θ = 0.2° to 1.0°. Specifically, as shown in Figure 2, a sample for integral intensity measurement is cut from the sheet obtained by the manufacturing method of the present invention and X-rays are incident from the X direction. Figure 2 illustrates a sheet obtained by laminating multiple films. As a result, a two-dimensional profile of small-angle X-ray scattering is obtained as shown in Figure 3(A). Next, as shown in Figure 3(B), the intensity in the region ±30° with respect to the meridian is integrated to obtain I Ｘ Ｖ I obtained by integrating the intensity in the region ±30° from the equator. Ｘ Ｌ We seek.

[0030] The scattering peak in the equatorial direction originates from regularly arranged crystalline lamellae in the in-plane direction of the sheet. The presence of regularly arranged crystalline lamellae increases the scattering intensity in the equatorial direction. In contrast, the streak in the meridional direction originates mainly from reflection from the gap surfaces remaining between the layers of the biaxially oriented film stacked in the Z direction. Therefore, if the orientation of the crystals in the biaxially oriented film is maintained or increased in the sheet, I Ｘ Ｌ This increases. On the other hand, if the interlayer fusion of the biaxially oriented film is sufficient, the gap surface remaining between the layers decreases, resulting in I Ｘ Ｖ The streak decreases. Therefore, I Ｘ Ｌ Large I Ｘ Ｖ A smaller size improves the transparency and mechanical properties of the sheet. Furthermore, in the α-crystal of polypropylene, when crystallization proceeds while crystalline lamellae (parent lamellae) are present, smaller lamellae (daughter lamellae) grow almost perpendicular to the parent lamellae. The long-period scattering peak originating from the daughter lamellae is I Ｘ Ｖ It is observed as such.

[0031] Figure 4 shows the integrated intensity I at the azimuthal angle of the small-angle X-scattering 2D profile in Example 10 and Comparative Example 8. Ｘ Ｌ This diagram shows the relationship between Tm and 2θ. ｏｕｔ In the sheet of Example 10 satisfying -T≧4(°C), Tm ｏｕｔCompared to the sheet of Comparative Example 8, which does not satisfy -T ≥ 4 (°C), it can be seen that there are more arranged crystal lamellae (parent lamellae).

[0032] Figure 5 shows the integrated intensity I at the azimuthal angle of the small-angle X-scattering 2D profile in Example 10 and Comparative Example 8. Ｘ Ｖ This diagram shows the relationship between Tm and 2θ. ｏｕｔ In the sheet of Example 10 satisfying -T≧4(°C), Tm ｏｕｔ Broad scattering peaks originating from daughter lamellae, which are absent in the sheet of Comparative Example 8 where -T ≥ 4 (°C), were observed in the range of 2θ = 0.2° to 1.0°, suggesting that crystallization proceeded in the presence of crystalline lamellae (parent lamellae). This acceleration of crystallization further improves the mechanical properties.

[0033] (3) Mechanical properties The sheets obtained by the manufacturing method of the present invention have excellent mechanical properties. For example, the sheets obtained by the manufacturing method of the present invention have a tensile modulus of 2,500 MPa or more (JIS K7161-2). Furthermore, the sheets obtained by the manufacturing method of the present invention also have excellent cold impact resistance. For example, the sheets obtained by the manufacturing method of the present invention have a surface impact strength of 5 J or more (-30°C, JIS K7211-2).

[0034] (4) Transparency The sheets obtained by the manufacturing method of the present invention have excellent transparency. For example, the sheets obtained by the manufacturing method of the present invention have a total haze of 25% or less (ISO 14782). The smaller the total haze value of the sheet, the better the transparency, preferably 20% or less.

[0035] (5) Surface The surface of the sheet obtained by the manufacturing method of the present invention can be given functional groups as described above. Oxygen-containing functional groups are preferred. Examples of oxygen-containing functional groups include carboxyl groups, carboxylate groups, acid anhydride groups, hydroxyl groups, aldehyde groups, epoxy groups, etc. These functional groups improve the adhesion between the sheet obtained by the manufacturing method of the present invention and other materials. In particular, a member coated with a sheet obtained by the manufacturing method of the present invention having such functional groups exhibits excellent gasohol resistance, which is resistance to gasoline mixed with alcohol. From this viewpoint, acid anhydride groups are preferred among the functional groups. The functional groups may be present on any surface of the sheet obtained by the manufacturing method of the present invention, but it is preferable that they be present on one or both sides of the main surface. The method for giving functional groups is as described above.

[0036] (6) Polypropylene In the present invention, polypropylene refers to a polymer mainly composed of polypropylene. The polypropylene used for the first layer of the sheet obtained by the manufacturing method of the present invention is preferably propylene homopolymer (HOMO) or propylene random copolymer (RACO) containing ethylene and at least one of C4-C10-αolefin as comonomers in an amount of 5.0% by weight or less. HOMO or RACO with a low comonomer content is particularly preferred due to its excellent rigidity and transparency. The polypropylene used for the second layer of the sheet obtained by the manufacturing method of the present invention is preferably RACO containing ethylene and at least one of C4-C10-αolefin as comonomers in an amount of 15% by weight or less. RACO with a high comonomer content is particularly preferred due to its excellent adhesion after fusion with the first layer.

[0037] These polypropylenes can be produced according to known methods. Generally, known polymerization catalysts for polypropylene include (A) solid catalysts containing magnesium, titanium, halogens, and electron donor compounds, (B) organoaluminum compounds, and (C) catalysts containing external electron donor compounds, as well as metallocene catalysts. Any of these catalysts can be used to produce the polypropylene of the present invention. Examples of electron donor compounds in component (A) (also called "internal electron donor compounds") include phthalate compounds, succinate compounds, and diether compounds, and any of these internal electron donor compounds can be used in the present invention. However, catalysts containing succinate compounds as internal electron donor compounds are preferred because they result in a broad molecular weight distribution and good biaxial stretchability of the obtained polypropylene.

[0038] (7) Additives The sheet obtained by the manufacturing method of the present invention may contain a nucleating agent. The amount of the nucleating agent is more than 0 parts by weight and 1.0 part by weight or less, preferably 0.05 to 0.5 parts by weight, per 100 parts by weight of polypropylene. A nucleating agent is an additive (transparency nucleating agent) used to control the size of the crystalline components in the resin to reduce transparency. The nucleating agent is not particularly limited and may be one that is commonly used in the field, but it is preferable to select from nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate ester-based nucleating agents, triaminobenzene derivative nucleating agents, carboxylate metal salt nucleating agents, and xylitol-based nucleating agents. An example of a nonitol-based nucleating agent is 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonitol. An example of a sorbitol-based nucleating agent is 1,3:2,4-bis-o-(3,4-dimethylbenzylidene)-D-sorbitol. Examples of phosphate ester-based nucleating agents include lithium salt-based nucleating agents such as phosphate-2,2'-methylenebis(4,6-di-tert-butylphenyl).

[0039] The sheets obtained by the manufacturing method of the present invention may also contain conventional additives commonly used in polyolefins, such as antioxidants, chlorine absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, antifogging agents, flame retardants, dispersants, copper pollution inhibitors, neutralizing agents, plasticizers, crosslinking agents, peroxides, oil spreaders, and other organic and inorganic pigments. The amount of each additive may be a known amount. Furthermore, synthetic resins or synthetic rubbers other than polypropylene may be included, to the extent that they do not impair the effects of the present invention. The synthetic resins or synthetic rubbers may be one type or two or more types.

[0040] 3. Applications The sheets obtained by the manufacturing method of the present invention have a high degree of orientation and specific higher-order structural parameters in the in-plane direction, and the degree of orientation has little dependence on the thickness direction, so they are lightweight as polypropylene while having excellent mechanical properties. In addition, the sheets obtained by the manufacturing method of the present invention also have excellent transparency. Therefore, they can be suitably used for food containers and lids, general merchandise, home appliance parts, daily necessities, etc. Furthermore, by laminating multiple sheets obtained by the manufacturing method of the present invention and pressing or fusing them, thicker sheets and larger molded bodies can be obtained while maintaining the orientation, etc. Therefore, the sheets obtained by the manufacturing method of the present invention are also useful as automobile parts, electrical and electronic components, housing members, toy members, furniture members, building material members, industrial materials, logistics materials, agricultural materials, etc.

[0041] 1. Preparation of Biaxially Oriented Films Each of the biaxially oriented films shown in Table 1 was prepared as follows: [Biaxially Oriented Film A] Solid catalyst component (1) was prepared according to the preparation method described in the examples of Japanese Patent Application Publication No. 2011-500907. Specifically, it was done as follows: 250 mL of TiCl was added to a 500 mL four-necked round-bottom flask purged with nitrogen. ４ It was introduced at 0°C. While stirring, 10.0 g of finely spherical MgCl was added. ２ 1.8C ２ H ５OH (prepared according to the method described in Example 2 of U.S. Patent 4,399,054, however, operated at 3,000 rpm instead of 10,000 rpm) and 9.1 mmol of diethyl-2,3-(diisopropyl) succinate were added. The temperature was raised to 100°C and held for 120 minutes. Then, stirring was stopped, the solid product was allowed to settle, and the supernatant was aspirated. The following procedure was then repeated twice: 250 mL of fresh TiCl ４ The mixture was added and reacted at 120°C for 60 minutes, and the supernatant was drawn up. The solid was washed six times with anhydrous hexane (6 × 100 mL) at 60°C to obtain solid catalyst (1).

[0042] The solid catalyst (1) obtained above was contacted with triethylaluminum (TEAL) and diisopropyldimethoxysilane (DIPMS) in amounts such that the weight ratio of TEAL to solid catalyst (1) was 11 and the weight ratio of TEAL / DIPMS was 3, at 12°C for 24 minutes. The resulting catalyst system was prepolymerized by holding it in a suspended state in liquid propylene at 20°C for 5 minutes to obtain prepolymerization catalyst (S). Prepolymerization catalyst (S) was introduced into a polymerization reactor, and propylene was supplied as the monomer. Small amounts of ethylene and hydrogen as molecular weight adjusters were also supplied so that the ethylene concentration in the polymerization reactor was 0.118 mol% and the hydrogen concentration was 700 mol ppm. A propylene-ethylene copolymer was synthesized by adjusting the polymerization temperature to 70°C and the polymerization pressure to 3.0 MPa. To 100 parts by weight of the obtained polymer, 0.2 parts by weight of an antioxidant (BASF B225) and 0.05 parts by weight of a neutralizing agent (calcium stearate manufactured by Tannan Chemical Industry Co., Ltd.) were added and mixed by stirring in a Henschel mixer for 1 minute. The mixture was melt-kneaded at a cylinder temperature of 230°C using a Nakatani Machinery Co., Ltd. NVC φ50 mm single-screw extruder, and the extruded strand was cooled in water and then cut with a pelletizer to obtain a pelletized polymer composition (a). The ethylene content of polymer composition (a) was 0.5% by weight, and the MFR (temperature 230°C, load 2.16 kg) was 3.0 g / 10 min.

[0043] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger) was obtained from polymer composition (a) at a molding temperature of 230°C. Next, the raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner GmbH) to obtain a biaxially oriented film A with a thickness of 50 μm.

[0044] [Biaxially oriented film B] A solid catalyst (2) was prepared by the method described in Example 1 of European Patent No. 674991. The solid catalyst is MgCl ２ Ti and diisobutyl phthalate as an internal donor were supported on top of the solid catalyst (2) in the manner described in the above-mentioned patent publication. The solid catalyst (2) obtained above was contacted with TEAL and dicyclopentyl dimethoxysilane (DCPMS) in amounts such that the weight ratio of TEAL to the solid catalyst was 11 and the weight ratio of TEAL / DCPMS was 3, at -5°C for 5 minutes. The obtained catalyst system was prepolymerized by holding it in a suspension state in liquid propylene at 20°C for 5 minutes. After introducing the obtained prepolymer into a polymerization reactor, hydrogen, propylene, and ethylene were fed in. Then, a propylene-ethylene copolymer was obtained by adjusting the polymerization pressure at a polymerization temperature of 75°C, a hydrogen concentration of 0.44 mol%, and an ethylene concentration of 1.07 mol%. To 100 parts by weight of the obtained polymer, 0.2 parts by weight of an antioxidant (BASF B225) and 0.05 parts by weight of a neutralizing agent (calcium stearate manufactured by Tannan Chemical Industry Co., Ltd.) were added and mixed by stirring in a Henschel mixer for 1 minute. The mixture was melt-kneaded at a cylinder temperature of 230°C using a Nakatani Machinery Co., Ltd. NVC φ50 mm single-screw extruder, and the extruded strand was cooled in water and then cut with a pelletizer to obtain a pelletized polymer composition (b). Polymer composition (b) contained 4.0% by weight of ethylene-derived units and had an MFR (temperature 230°C, load 2.16 kg) of 7.5 g / 10 min.

[0045] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger) was obtained from polymer composition (b) at a molding temperature of 230°C. The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner GmbH) to obtain a biaxially oriented film B with a thickness of 50 μm.

[0046] [Biaxially oriented film C] The polymer composition (c) is a propylene-ethylene-butene-1 copolymer (propylene: 90% by weight, ethylene: 4% by weight, butene: 6% by weight), with an MFR of 5.5 g / 10 min and a density of 0.90 g / cm³ at a temperature of 230°C and a load of 2.16 kg. ３ A RACO was used. Using a 25 mmφ 3-type 3-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger) was obtained from the polymer composition (c) at a molding temperature of 230°C. The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV manufactured by Bruckner GmbH) to obtain a biaxially oriented film C with a thickness of 50 μm.

[0047] [Biaxially Oriented Film D] The solid catalyst component (2) used in the preparation of biaxially oriented film B was contacted with TEAL and cyclohexylmethyldimethoxysilane (CHMMS) in amounts such that the weight ratio of TEAL to the solid catalyst was 8 and the weight ratio of TEAL / CHMMS was 6.5, at -5°C for 5 minutes. The resulting catalyst system was prepolymerized by holding it in a suspended state in liquid propylene at 20°C for 5 minutes. After introducing the obtained prepolymer into a polymerization reactor, hydrogen, propylene, and ethylene were fed in. Then, a propylene-ethylene copolymer was obtained by adjusting the polymerization pressure at a polymerization temperature of 75°C, a hydrogen concentration of 0.03 mol%, and an ethylene concentration of 0.13 mol%. To 100 parts by weight of the obtained polymer, 0.2 parts by weight of an antioxidant (BASF B225) and 0.05 parts by weight of a neutralizing agent (calcium stearate manufactured by Tannan Chemical Industry Co., Ltd.) were added and mixed by stirring in a Henschel mixer for 1 minute. The mixture was melt-kneaded using a Nakatani Machinery Co., Ltd. NVC φ50 mm single-screw extruder at a cylinder temperature of 230°C, and the extruded strand was cooled in water and then cut with a pelletizer to obtain a pelletized polymer composition (d). Polymer composition (d) contained 0.5% by weight of ethylene-derived units and had an MFR (temperature 230°C, load 2.16 kg) of 2.5 g / 10 min.

[0048] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger) was obtained from the polymer composition (d) at a molding temperature of 230°C. The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner GmbH) to obtain a biaxially oriented film D with a thickness of 50 μm.

[0049] [Biaxially Oriented Film E] The same prepolymerization catalyst (S) used in the preparation of biaxially oriented film A was introduced into a polymerization reactor to obtain a propylene homopolymer. During polymerization, the temperature and pressure were adjusted, and hydrogen was used as a molecular weight adjuster. The polymerization temperature was 70°C, and the hydrogen concentration was 0.25 mol%. To 100 parts by weight of the obtained polymer, 0.2 parts by weight of an antioxidant (BASF B225) and 0.05 parts by weight of a neutralizing agent (calcium stearate manufactured by Tannan Chemical Industry Co., Ltd.) were added, and the mixture was stirred and mixed in a Henschel mixer for 1 minute. The mixture was then extruded using a single-screw extruder with a screw diameter of 50 mm (NVC manufactured by Nakatani Machinery Co., Ltd.) at a cylinder temperature of 230°C, the strands were cooled in water, and then cut with a pelletizer to obtain a pelletized polymer composition (e). The polymer composition (e) contained 0% by weight of ethylene-derived units, and its MFR (temperature 230°C, load 2.16 kg) was 10 g / 10 min.

[0050] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger) was obtained from polymer composition (d) at a molding temperature of 230°C. The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner GmbH) to obtain a biaxially oriented film E with a thickness of 50 μm.

[0051] [Biaxially Oriented Films AB-1, AB-2] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), the polymer composition (a) / polymer composition (b) was co-extruded at a molding temperature of 230°C to obtain a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger). The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner) to obtain biaxially oriented films AB-1 and AB-2 with a thickness of 50 μm. The thickness ratio of polymer composition (a) / polymer composition (b) was 90 / 10 for AB-1 and 95 / 5 for AB-2.

[0052] [Biaxially oriented films AC, AD, DB, DC, EB-1, EB-2] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), the films were co-extruded at a molding temperature of 230°C to obtain polymer composition (a) / polymer composition (c), polymer composition (a) / polymer composition (d), polymer composition (d) / polymer composition (b), polymer composition (d) / polymer composition (c), and polymer composition (e) / polymer composition (b), resulting in a base sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger). The base sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner), to obtain biaxially oriented films AC, AD, DB, DC, EB-1, and EB-2 with a thickness of 50 μm. The thickness ratio was 85 / 15 for EB-1, and 90 / 10 for AC, AD, DB, DC, and EB-2.

[0053] [Biaxially Oriented Film BAB] Using a 25 mmφ three-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), the polymer composition (b) / polymer composition (a) / polymer composition (b) was co-extruded at a molding temperature of 230°C to obtain a raw sheet with a thickness of 1.25 mm (size 10 cm x 10 cm or larger). The raw sheet was simultaneously biaxially stretched (5 times x 5 times) using a film stretching device (KARO-IV, manufactured by Bruckner GmbH) to obtain a biaxially oriented film BAB with a thickness of 50 μm. The thickness ratio was 10 / 80 / 10.

[0054] 2. Sheet Manufacturing [Example 1] Eleven biaxially oriented films A and ten biaxially oriented films B were alternately laminated to prepare a precursor in which the outermost layers of both films were biaxially oriented films A. A roll forming machine (induction heating jacket roller manufactured by Tokuden Co., Ltd., model JR-D0-W, roll diameter 200 mmφ x 2, roll face length 410 mm) was used as a heating element to heat-fuse the layers of the precursor together to produce a sheet. The molding conditions were as shown in Table 2. The sheet was then evaluated by the method described later.

[0055] [Example 2] A sheet was manufactured and evaluated in the same manner as in Example 1, using biaxially oriented film C instead of biaxially oriented film B.

[0056] [Example 3] Ten biaxially oriented films AB were laminated together, and one biaxially oriented film A was laminated on top of them to prepare a precursor in which both outermost layers were biaxially oriented film A. A sheet was manufactured and evaluated using this precursor in the same manner as in Example 1.

[0057] [Example 4] A sheet was manufactured and evaluated in the same manner as in Example 3, except that the heated roll molding take-up speed was changed.

[0058] [Example 5] A sheet was manufactured and evaluated in the same manner as in Example 3, except that the number of biaxially oriented films to be laminated was changed to make the sheet thickness 4 mm, and the heating roll temperature was changed.

[0059] [Examples 6-11] Sheets were manufactured and evaluated in the same manner as in Example 3, except that the biaxially oriented films to be laminated were changed as shown in Table 2.

[0060] [Example 12] A precursor was prepared by laminating 19 biaxially oriented films BAB and two biaxially oriented films A, one at each end, so that both outermost layers were biaxially oriented films A. A sheet was manufactured and evaluated using this precursor in the same manner as in Example 1.

[0061] [Comparative Example 1] A comparative sheet was manufactured and evaluated using only biaxially oriented film A in the same manner as in Example 1.

[0062] [Comparative Example 2] A comparative sheet was manufactured and evaluated in the same manner as in Comparative Example 1, except that the heating roll temperature was changed.

[0063] [Comparative Example 3] A precursor was prepared using only biaxially oriented film B. A comparative sheet was manufactured and evaluated using this precursor in the same manner as in Example 1. However, the heating roll temperature was as shown in Table 2.

[0064] [Comparative Example 4] A comparative sheet was manufactured and evaluated in the same manner as in Comparative Example 3, except that the heating roll temperature was changed.

[0065] [Comparative Examples 5-7] Precursors were prepared using only biaxially oriented film C, only biaxially oriented film D, and only biaxially oriented film E. Comparative sheets were manufactured and evaluated using these precursors in the same manner as in Example 1. However, for Comparative Example 5 (C only), the heating roll temperature was also changed.

[0066] [Comparative Example 8] A comparative sheet was manufactured and evaluated in the same manner as in Comparative Example 7, except that the heating roll temperature was changed.

[0067] [Comparative Example 9] A comparative sheet was manufactured and evaluated in the same manner as in Example 1, except that biaxially oriented film D was used instead of biaxially oriented film B.

[0068] [Comparative Example 10] A comparative sheet was manufactured and evaluated in the same manner as in Example 3, except that biaxially oriented film AD was used instead of biaxially oriented film AB-1.

[0069] [Comparative Example 11] A comparative sheet was manufactured and evaluated in the same manner as in Comparative Example 10, except that the heating roll temperature was changed.

[0070] 3. Evaluation (1) MFR was measured in accordance with JIS K7210-1 under conditions of a temperature of 230°C and a load of 2.16 kg. (2) Amount of ethylene-derived units (wt%) contained in the polymer composition. Samples dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene were measured using a Bruker AVANCE III HD400. １３ Using a C resonance frequency of 100 MHz, under the following conditions: measurement temperature 120°C, flip angle 45 degrees, pulse interval 7 seconds, sample rotation speed 20 Hz, and number of integration cycles 5000 times. １３ A 1C-NMR spectrum was obtained. Using the spectrum obtained above, the amount of ethylene-derived units (weight %) contained in the polymer composition was determined by the method described in the literature M. Kakugo, Y. Naito, K. Mizunuma and T. Miytake, Macromolecules, 15, 1150-1152 (1982). (3) I Ｘ Ｖ and I Ｘ ＬUsing an X-ray scattering instrument (MicroMax and NanoViewer, Rigaku Corporation), small-angle X-ray scattering measurements were performed by incidenting X-rays (wavelength: 0.154 nm) in the X direction onto the sheet, as shown in Figure 2. After removing the background from the obtained two-dimensional profile, the integrated intensity I at the azimuth angle in the equatorial (Y-axis) direction was analyzed. Ｘ Ｌ The integrated intensity I at the azimuth angle in the direction of the meridian (Z axis) Ｘ Ｖ The following was calculated. The integration region was defined as the range from the equator (Y-axis) and meridian (Z-axis) to an azimuth angle of ±30°. In this analysis, in order to avoid the effects of reflection from the sheet surface, the size of the X-ray incident beam at the sample irradiation position must be smaller than the thickness of the sheet. In this case, for a 1 mm thick sheet, the beam size at the sample irradiation position was set to 700 μm.

[0071] (4) Melting point (Tmh, Tml) by DSC Approximately 5 mg was sampled from the biaxially oriented film and weighed using an electronic balance. The sample was then measured using a differential thermal analyzer (DSC) (TA Instruments Q-200) and held at 30°C for 5 minutes, followed by heating to 230°C at a heating rate of 10°C / min to obtain a melting curve. For the peak temperature of the melting curve, Tmh was defined as the melting point of the first biaxially oriented polypropylene film, and Tml as the melting point of the second biaxially oriented polypropylene film. If multiple melting point peaks were observed in each film, the temperature of the largest peak was defined as the melting point. The melting point of the outermost layer was defined as Tmh. ｏｕｔ Tm ｏｕｔ = Tmh or Tm ｏｕｔ = Tml, but Tm is defined as the manner in which the high melting point component comes into contact with the heated object. ｏｕｔ It is preferable that = Tmh.

[0072] (5) Stiffness (Tensile Modulus) A multipurpose test specimen of type A2 as specified in JIS K7139 was machined from the obtained sheet as a molded body, and the tensile modulus was measured in accordance with JIS K7161-2 using a precision universal testing machine (Autograph AG-X 10kN) manufactured by Shimadzu Corporation, under the conditions of a temperature of 23°C, relative humidity of 50%, and a test speed of 1 mm / min.

[0073] (6) Cold impact resistance (surface impact strength) For the obtained sheets, in accordance with JIS K7211-2, using a HydroShot HITS-P10 manufactured by Shimadzu Corporation, the test specimens were placed on a support stand with an inner diameter of 40 mmφ in a chamber adjusted to -30°C, fixed with a sample holder with an inner diameter of 76 mmφ, and then struck with a striker with a hemispherical striking surface and a diameter of 12.7 mmφ at an impact speed of 1 m / s to determine the puncture energy (J). The average value of the puncture energy of each of the four test specimens was taken as the surface impact strength.

[0074] (7) Transparency (Haze) Transparency was evaluated by measuring the haze of the obtained sheets using HM-150 manufactured by Murakami Color Technology Laboratory Co., Ltd. in accordance with ISO 14782. Furthermore, in order to exclude the influence of surface irregularities of the sheets resulting from molding and cooling conditions, liquid paraffin was applied to the surface of the sheets with a brush and the haze was measured in the same manner. The former was defined as "total haze" and the latter as "internal haze". In addition, "external haze" ("total haze" - "internal haze") was defined to see the contribution of the sheet surface.

[0075] (8) Lamination State The central portion of the obtained sheet was sliced ​​with a thickness of 20 μm in the plane perpendicular to the surface using a rotary microtome (model: RU-S) manufactured by Japan Microtome Laboratory Co., Ltd. These slices were observed under crossed nicol conditions using a polarizing microscope (BX-50) manufactured by Olympus Corporation, and the lamination state was evaluated according to the following criteria: a: No delamination at all b: Some partially delaminated layers are visible c: Complete delamination d: Multilayer structure cannot be confirmed Figure 1 shows examples of lamination state a and lamination state b. In Figure 1 (1), the dark area is the second layer, and it can be seen that there is no delamination between the first and second layers. Figure (2) is a sheet composed of multiple first layers, and the dark areas indicate delamination.

[0076]

[0077]

[0078]

[0079] Table 2 clearly shows that the sheets obtained by the manufacturing method of the present invention have excellent transparency and mechanical properties. In all of Examples 1 to 12, a multilayer structure with no delamination was observed. On the other hand, in Comparative Examples 9 and 10, partial delamination occurred when force was applied during section slicing with a microtome. It is thought that the tensile modulus values ​​obtained were also lower because delamination occurred during measurement. In Comparative Examples 1, 3, 6, and 7, complete delamination occurred with only slight force, making it impossible to properly slice the sections with a microtome. It is thought that the values ​​obtained were also lower because delamination occurred during tensile modulus measurement. In Comparative Examples 2, 4, 5, 8, and 11, the sheets melted in the stretching roll, so a multilayer structure could not be confirmed in the obtained sheets.

[0080] 1. Polypropylene sheet 2. Incident X-rays 20. Beam size at the irradiation position on the sample

Claims

DEPCT641. Method for producing polypropylene sheets with a thickness of 0.5 to 5 mm, which includes assembly; Step 1: Preparation of the precursor where a first-stretched biaxially drawn polypropylene film with a thickness of less than 0.15 mm and a melting point Tmh, and a second-stretched biaxially drawn polypropylene film with a thickness of less than 0.15 mm and a melting point Tml, are alternately stacked; and Step 2: Introducing a heating element into contact with the outermost layer of the precursor to heat-seal the film layers at a temperature where Tmh-Tml is greater than or equal to.

1. A method for producing plates according to claim 1 where the melting point Tmout of the outermost layer and the temperature T of the heating element are under the following conditions: Tmout-T greater than or equal to 4 (degrees Celsius).

3. A manufacturing method according to claim 1 or 2 where step 2 is performed using a hot roller as the heating element. 4.One of the fabrication methods under claims 1 through 3 in which the polypropylene sheet has a Dh / D1 ratio of 1 to 30, where Dh is the thickness of the likely layer from the first biaxially drawn polypropylene film and D1 is the thickness of the likely layer from the second biaxially drawn polypropylene film.

5. One of the fabrication methods under claims 1 through 4 in which the polypropylene sheet has a total intensity of IXV at an azimuth angle determined from a narrow-angle X-ray scattering two-dimensional profile.

6. A manufacturing method under one of the claims 1 through 5, where step 1 includes the co-extrusion of the first biaxially drawn polypropylene film raw material and the second biaxially drawn polypropylene film raw material to prepare a composite sheet of a certain number of layers and then biaxially stretching the composite sheet to prepare a precursor. 7.A method for the manufacture of a molded object which involves the preparation of polypropylene sheets by any of the methods described in claims 1 through 6 and molding the polypropylene sheets into a molded object.