Method for manufacturing crystalline resin sheet

Abstract

Provided is a method for producing a crystalline resin sheet in which a sheet-like crystalline resin composition containing a crystalline resin and a melt-type nucleating agent is sandwiched and rolled in a molten state by a pair of nip rolls, when the radius of the pair of nip rollers is R, the average thickness of the rolled sheet is L, and the sheet pulling speed in the pair of nip rollers is V, the average elongation strain speed [epsilon] (R, L, V) in the sheet elongation direction, which is represented by a specific formula, is adjusted so as to exceed 30 s <-1 > and 80 s <-1 > or less.

Description

Technical Field

[0001] The present invention relates to a method for producing a crystalline resin sheet. This application claims priority based on Japanese Patent Application No. 2022-096354 filed in Japan on June 15, 2022, and the contents are incorporated herein by reference. Background Art

[0002] In the past, the following technology has been disclosed: when a melt of a crystalline resin such as polypropylene is calendered to form a sheet (including a film with a thickness of about 0.1 mm), the elongation strain rate is adjusted to make the orientation of the polymer chains in the melt consistent, thereby improving the crystallinity (for example, Patent Documents 1 to 4, Non-Patent Documents 1 and 2). Patent Document 2 discloses a production method in which a sheet containing nano-sized oriented crystals (NOC; Nano-oriented crystal) at a high ratio can be produced on an industrial scale by setting the elongation strain rate to a critical value or higher. Since sheets containing NOC are excellent in mechanical strength, heat resistance, transparency, etc., they are expected to be effectively used as a substitute for engineering plastics. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent No. 5339350 Patent Document 2: Japanese Patent No. 5534458 Patent Document 3: Japanese Patent No. 5765707 Patent Document 4: Japanese Patent No. 5995201 Non-patent literature

[0004] Non-patent document 1: K. Okada et al., Polym. J., 42, 464-473 (2010) Non-patent document 2: K. Okada et al., Polym. J., 50, 167-176 (2018) Summary of the invention Technical problem to be solved by the invention

[0005] In the previous research and development of NOC, on the basis of simplifying the composition of the crystalline resin melt without mixing impurities into the melt, in order to orient the polymer in the melt and crystallize it, the principle of adjusting the temperature of the resin supplied to the calender, the radius of the nip roll, the thickness of the sheet after the press stretching, and the sheet pulling speed was adopted. Thus, for example, according to the conditions of the elongation strain rate disclosed in Patent Document 2, it is also possible to produce an orientation function f representing the orientation degree of the polymer chain in the crystal containing NOC. c , crystallinity X c The sheet has a tensile modulus of elasticity exceeding 0.9 and excellent mechanical properties and transparency.

[0006] However, the conventional elongation strain rate that can obtain the sheet with the most excellent properties as described above is several hundred seconds. -1 If it is reduced to tens of seconds -1 When the ratio is about 0.1 Å, a sheet having excellent properties to a certain extent can be obtained, and the production conditions related to the elongation strain rate can be relaxed or expanded, which is preferred.

[0007] Therefore, the present invention provides a method for producing a crystalline resin sheet having a lower elongation strain rate than conventional ones and having high NOC, mechanical properties and transparency. Solutions for solving technical problems

[0008] The present invention has the following aspects. [1] A method for producing a crystalline resin sheet, comprising: clamping a sheet-like crystalline resin composition in a molten state between a pair of clamping rollers and rolling the sheet, wherein the crystalline resin composition comprises a crystalline resin and a molten nucleating agent, and when the radius of the pair of clamping rollers is set to R, the average thickness of the sheet after rolling is set to L, and the sheet pulling speed in the pair of clamping rollers is set to V, so that the average elongation strain rate ε(R, L, V) in the elongation direction of the sheet represented by the following formula (1) is greater than 30 s -1 And 80s -1 Adjust in the following way.

[0009] [Number 1]

[0010] [2] The method for producing a crystalline resin sheet according to [1], wherein the sheet-like crystalline resin composition in a molten state is obtained by discharging the crystalline resin composition from a die having a slit-shaped opening. [3] The method for producing a crystalline resin sheet according to [1] or [2], wherein the rolled sheet is peeled off from the nip roll, and gas is sprayed toward a portion of the rolled sheet separated from the nip roll. [4] The method for producing a crystalline resin sheet according to any one of [1] to [3], wherein a peripheral surface of at least one of the pair of nip rolls is previously subjected to a mold release treatment. [5] The method for producing a crystalline resin sheet according to any one of [1] to [4], wherein the temperature of the crystalline resin composition immediately before rolling is set to T e , the temperature of the pair of clamping rollers is set to T r The crystallization temperature of the crystalline resin composition measured by DSC is defined as T c , set the melting point to T m By adjusting the temperature T e and the temperature T r , so that (T e -T m ) is in the range of -15°C to 130°C, and (T c -T r ) value ranges from -10℃ to 130℃. [6] The method for producing a crystalline resin sheet according to any one of [1] to [5], wherein the temperature of the crystalline resin composition immediately before rolling is set to T e , the temperature of the pair of clamping rollers is set to T r The crystallization temperature of the crystalline resin composition measured by DSC is defined as T c , set the melting point to T m By adjusting the temperature T e and the temperature T r , so that (T e -T m ) is in the range of 0℃~90℃, and (T c -T r ) value ranges from 0℃ to 110℃. Effects of the Invention

[0011] According to the production method of the present invention, since the crystalline resin composition supplied to the calendar contains a melt-type nucleating agent, a crystalline resin sheet having a more complete NOC described below and high mechanical properties and transparency can be produced even at a lower elongation strain rate than conventional ones. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram showing a state in which a sheet-like crystalline resin composition in a molten state is rolled by a pair of nip rolls. Figure 2These are polarizing microscope images of the sample piece of Example 2 (through, edge, end view). Figure 3 It is the SAXS pattern of the sample piece of Example 2 (perspective view, edge view, end view). Figure 4 It is the WAXD pattern of the sample piece of Example 2 (perspective view, edge view, end view). DETAILED DESCRIPTION

[0013] A first aspect of the present invention is a method for producing a crystalline resin sheet, wherein a sheet-shaped crystalline resin composition in a molten state is sandwiched between a pair of nip rolls and rolled.

[0014] In this specification, "sheet" is a conceptual term that includes "film". Usually, objects with a thickness of about 0.1 mm are sometimes called films, and objects with a thickness of 0.15 mm or more are sometimes called sheets to distinguish between the two. However, in this specification, unless otherwise specified, no term is used to distinguish between the two.

[0015] The sheet forming device used in the manufacturing method of this mode is not particularly limited as long as it can supply the melt of the sheet-like crystalline resin composition to a pair of clamping rollers and roll it, and a known device can be applied. For example, the continuous molding machine 10 and the intermittent molding machine 20 briefly exemplified in Patent Document 2 can be cited. At least one of the pair of clamping rollers is configured to be able to rotate in the elongation direction of the sheet. In addition, the radius R of the pair of clamping rollers is equal to each other.

[0016] The sheet forming device preferably has a die head for ejecting a molten crystalline resin composition. From the aspect of facilitating the supply of the crystalline resin composition in sheet form to the pair of clamping rollers, the die head preferably has a slit-shaped opening (ejection portion). The width of the slit-shaped opening (die lip gap), that is, the thickness of the sheet-shaped crystalline resin composition supplied to the pair of clamping rollers, can be, for example, about 0.1 mm to 5 mm, preferably about 0.5 mm to 1.5 mm.

[0017] The temperature of the crystalline resin composition in the molten state of the present embodiment can be any temperature before calendering at which the composition can be made into a sheet shape and supplied to the pair of clamping rollers and can be formed into a sheet by calendering. It can be a temperature above the melting point of the crystalline resin measured by DSC, or a temperature below the melting point of the crystalline resin measured by DSC (a temperature that becomes a supercooled state).

[0018] The temperature of the crystalline resin composition immediately before rolling (after being ejected from the die head and immediately before being rolled) in the pair of nip rolls is defined as Te , the temperature of the pair of clamping rollers is set to T r The crystallization temperature of the crystalline resin composition measured by DSC is defined as T c , set the melting point to T m At this time, it is preferred to adjust the temperature T e and the temperature T r So that (T e -T m ) value range is -15℃~130℃, and (T c -T r ) is in the range of -10°C to 130°C, and more preferably (T e -T m )=-5℃~110℃ and (T c -T r )=-5℃~120℃, more preferably (T e -T m )=0℃~90℃ and (T c -T r )=0℃~110℃, especially preferably (T e -T m )=10℃~70℃ and (T c -T r )=5℃~110℃, most preferably (T e -T m )=20℃~50℃ and (T c -T r )=10° C. to 110° C. When each temperature is within the above range, a crystalline resin sheet containing NOC and having high mechanical properties and transparency can be obtained more easily.

[0019] The temperature T of the crystalline resin composition e This is a value of the temperature of the resin composition immediately after being ejected from the die and before being calendered. The temperature T of the pair of clamping rollers r is the value of the surface temperature of each clamping roller. The temperature T of the pair of clamping rollers r are equal to each other. T e and T r The measurement may be performed by any method, but it is preferable to perform the measurement using a non-contact type thermometer such as a radiation thermometer.

[0020] In the manufacturing method of this embodiment, in order to prevent the rolled sheet of the crystalline resin composition from being wound around any one of the pair of nip rollers, it is preferred that when the rolled sheet is peeled off from the nip rollers in order to convey the rolled sheet to the subsequent stage, gas is sprayed toward the portion where the rolled sheet is separated from the nip rollers. The spraying speed may be, for example, 50 m / s. 3 / min~200m 3 / point. In order to easily peel the rolled sheet from the circumferential surface, it is preferred to perform a demolding treatment on the circumferential surface of at least one of the pair of nip rollers in advance. For example, a demolding treatment may be performed by coating or spraying a release agent such as silicone or fluororesin on the circumferential surface.

[0021] The crystalline resin composition includes a crystalline resin and a melt-type nucleating agent.

[0022] The crystalline resin is a thermoplastic resin that can be stretched and molded, and examples thereof include polyolefin (or polyalkylene), polyamide, polyester, polyether, liquid crystal polymer, fluororesin, vinyl resin, polyphenylene sulfide, polylactic acid, polyacetal, and polyether nitrile. Examples of the polyolefin include polyethylene, isotactic polypropylene (iPP), syndiotactic polypropylene, poly(1-butene), poly(4-methylpentene), and crystalline ethylene-propylene copolymers. The isotactic fraction (mmmm) described below, which represents the stereoregularity of the iPP, is preferably 93% or more, and more preferably 97% or more. Examples of the polyamide include nylon 6, nylon 66, nylon 12, and wholly aromatic polyamides. Examples of the polyester include aliphatic aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; wholly aromatic polyesters; and aliphatic polyesters such as polyethylene succinate and polybutylene succinate. Examples of the polyether include polyetheretherketone and the like. Examples of the liquid crystal polymer include liquid crystal polyesters. Examples of the fluororesin include polytetrafluoroethylene and polyvinylidene fluoride. Examples of the vinyl resin include syndiotactic polystyrene, isotactic polystyrene, polyvinyl alcohol, and polyvinyl chloride. These crystalline resins may be used alone or in combination of resins of the same kind but having different molecular weights.

[0023] As the above-mentioned melt-type nucleating agent, there is no limitation as long as it is a substance that is compatible with the crystalline resin in a molten state to form a compatible melt and gels before the crystalline resin is solidified to form a three-dimensional (3D) network structure. It is preferably selected from nonanol-based nucleating agents, xylitol-based nucleating agents, sorbitol-based nucleating agents, and triamide-based nucleating agents. As a nucleating agent having a nonanol-based structure, for example, 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonanol can be listed, and as a nucleating agent having a xylitol-based structure, for example, bis-1,3:2,4-(5',6',7',8'-tetrahydro-2-naphthaldehydebenzylidene)1-allyl xylitol, bis-1,3:2,4-(3',4'-dimethylbenzylidene) As the nucleating agent having a sorbitol-based structure, for example, bis-1,3:2,4-(4'-ethylbenzylidene)1-allyl sorbitol, bis-1,3:2,4-(3'-methyl-4'-fluoro-benzylidene)1-propyl sorbitol, bis-1,3:2,4-(3',4'-dimethylbenzylidene)1'-methyl-2'-propenyl sorbitol, bis-1,3:2,4-(3',4'-dimethylbenzylidene)1'-methyl-2'-propenyl sorbitol, Benzyl 2',3'-dibromopropyl sorbitol, bis-1,3,2,4-dibenzylidene 2'-bromo-3'-hydroxypropyl sorbitol, bis-1,3:2,4-(3'-bromo-4'-ethylbenzylidene)-1-allyl sorbitol, mono-2,4-(3'-bromo-4'-ethylbenzylidene)-1-allyl sorbitol, bis-1,3:2,4-(4'-ethylbenzylidene)1-allyl sorbitol, bis-1,3 : 2,4-(3',4'-dimethylbenzylidene) 1-methylsorbitol, bis(p-methylbenzylidene) sorbitol, 1,3:2,4-bis-o-(4-methylbenzylidene)-D-sorbitol, as nucleating agents having a triamide structure, for example, 1,3,5-tris(2,2-dimethylpropionamide)benzene, 1,2,3-propanetricarboxylic acid N,N',N"-tris(2-methylcyclohexyl)amide, etc. As the nonanol-based commercially available melt-type nucleating agent used in the composition of the present invention, for example, Millad NX8000 (manufactured by Milliken) can be cited, as the sorbitol-based commercially available melt-type nucleating agent, for example, RiKAFAST R-1 (manufactured by New Japan Chemical Co., Ltd.), Millad 3988 (manufactured by Milliken), GEL ALL E-200 (manufactured by New Japan Chemical Co., Ltd.), GEL ALL MD (manufactured by New Japan Chemical Co., Ltd.) can be cited, as the triamide-based commercially available melt-type nucleating agent, for example, IRGACLEAR XT386 (manufactured by BASF), RIKACLEAR PC1 (manufactured by New Japan Chemical Co., Ltd.) etc. The melt-type nucleating agent may be used alone or in combination of two or more. The reason why crystalline resins can generate NOCs significantly and easily by adding a molten transparent nucleating agent is believed to be that in the process of the nucleating agent self-organizing the 3D grid under the elongation of the compatible melt, the polymer chains of the crystalline resin generate non-uniform cores in the epitaxial direction in the 3D grid of the nucleating agent, and the 3D grid is efficiently extended in the MD (machine direction), thereby suppressing the entropy relaxation of the polymer chains of the crystalline resin before the nucleus is generated and grown. However, it is not limited to this assumption.

[0024] The content of the melt-type nucleating agent relative to the total mass of the crystalline resin composition is preferably 0.01% to 5% by mass, more preferably 0.1% to 2% by mass, and further preferably 0.2% to 1% by mass. Within the above range, the effect of the present invention can be further obtained. Even if the content exceeds the upper limit of the range, the effect has reached the limit, which is not preferred from the economic point of view.

[0025] As long as the effects of the present invention are not impaired, the crystalline resin composition of the present invention may include, as an optional component, a synthetic resin or synthetic rubber other than the crystalline resin, and an additive other than the melt-type nucleating agent. These optional components may be only one or more. The content may be set to a known amount.

[0026] Examples of additives other than the melt-type nucleating agent that the crystalline resin composition of the present invention may contain include inorganic fillers, antioxidants, neutralizers, nucleating agents other than the melt-type nucleating agent, weathering agents, pigments (organic or inorganic), internal lubricants, external lubricants, anti-blocking agents, antistatic agents, chlorine absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, slip agents, antifogging agents, flame retardants, dispersants, copper damage inhibitors, plasticizers, foaming agents, bubble inhibitors, crosslinking agents, peroxides, oil extenders, and the like. These additives may be present alone or in combination of two or more. The content thereof may be a known amount.

[0027] The sheet-like crystalline resin composition in a molten state can be obtained by mixing the crystalline resin, the melt-type nucleating agent, and the optional components as required by a known method. From the viewpoint of easily carrying out the production method of the present embodiment, the crystalline resin composition preferably contains only the crystalline resin and the melt-type nucleating agent without containing any arbitrary components.

[0028] The radius of the nip roll for rolling the crystalline resin composition in a molten state in a sheet form is denoted by R, the average thickness of the sheet after rolling is denoted by L, and the sheet drawing speed of the nip roll is denoted by V. At this time, the average elongation strain rate ε(R, L, V) in the elongation direction of the sheet represented by the above formula (1) is adjusted to be more than 30 s. -1 And 80s -1 The target crystalline resin sheet can be obtained as follows. The average elongation strain rate ε is preferably less than 80 s -1 .

[0029] The average elongation strain rate ε of this embodiment is preferably 32 s, for example. -1 ~80s -1 , preferably 35s -1 ~80s -1 , more preferably more than 37s -1 And less than 80s -1 . When the content is within the above range, a crystalline resin sheet containing more complete NOC described below can be obtained more easily. Since the crystalline resin composition of this embodiment contains the melt-type nucleating agent, even when the average elongation strain rate ε is set to the order of tens per second, which is one level lower than the conventional order of hundreds per second, the crystalline resin sheet molded from the crystalline resin composition can contain NOC. Thus, the sheet pulling speed V defined as the numerator of the formula (1) can be reduced compared to the prior art, thereby manufacturing at a low speed. In addition, the radius R of the clamping roller defined in the square root of the denominator of the formula (1) can be increased to manufacture, or the average thickness L of the sheet can be increased to manufacture.

[0030] Here, the average elongation strain rate ε shown in the formula (1) is derived for the condition that the clamping roll does not deform in Patent Document 2 and the paper by Okada et al. (Non-Patent Document 2). In the sheet manufacturing method of Patent Document 2, the average elongation strain rate ε at which the optical characteristics derived from NOC suddenly change (NOC content increases sharply) observed in the manufactured polymer sheet is specifically defined as the critical elongation strain rate ε*. In this embodiment, the manufactured crystalline resin sheet only needs to contain NOC, and it is not necessary to contain NOC at a high ratio to the extent that its optical characteristics suddenly change, as described in Patent Document 2. It should be noted that whether the crystalline resin sheet contains NOC can be easily determined based on known judgment criteria by polarizing microscope observation or SAXS measurement. As shown in the embodiments and comparative examples described later, according to the manufacturing method of the present embodiment, a crystalline resin sheet containing NOC can be obtained even if the average elongation strain rate ε is reduced, and the critical elongation strain rate ε* in the manufacturing method of the present embodiment is smaller than the critical elongation strain rate ε* in patent document 2 and the paper by Okada et al. (non-patent document 1).

[0031] In (1), the sheet drawing speed V can be, for example, 0.5 m / min to 100 m / min, preferably 1.0 m / min to 50 m / min, more preferably 2.0 m / min to 30 m / min, and further preferably 4.0 m / min to 20 m / min. Here, the sheet drawing speed V is a value calculated based on the moving speed of the roller surface caused by the rotation. In the formula (1), the radius R of the pair of clamping rollers can be set to, for example, 50 mm to 250 mm, preferably 70 mm to 200 mm, more preferably 80 mm to 180 mm, and even more preferably 90 mm to 180 mm. Here, the radius R of the clamping roller is a value of 1 / 2 of the diameter of the clamping roller measured using a steel tape measure. In the formula (1), the average thickness L of the sheet after rolling can be, for example, 100 μm to 3000 μm, preferably 100 μm to 1500 μm, more preferably 100 μm to 1000 μm, and further preferably 120 μm to 1000 μm. Here, the average thickness L of the sheet after rolling is a value measured by a known method such as a β-line film thickness meter. By adopting the above preferred V, R, and L, it is easy to adjust the average elongation strain rate ε(R, L, V) in the sheet elongation direction represented by the above formula (1) to more than 30 s. -1 .

[0032] The crystalline resin sheet obtained by the production method of this embodiment preferably has the following physical properties.

[0033] The average thickness of the crystalline resin sheet is preferably 0.12 mm or more, more preferably 0.15 mm or more, and further preferably 0.3 mm or more. The thicker the thickness, the more the mechanical properties can be improved. The upper limit of the thickness is not particularly limited, and for example, about 5 mm can be listed as a target.

[0034] The tensile modulus of at least one of the MD (Machine Direction) and TD (Transverse Direction) of the crystalline resin sheet is preferably 2000 MPa or more, more preferably 2500 MPa or more, and further preferably 3000 MPa or more. The upper limit is not particularly limited, and for example, about 5000 MPa can be listed as a target. Here, the tensile modulus is a value measured at room temperature 23° C. in accordance with JIS K7161-2.

[0035] The total haze and internal haze of the crystalline resin sheet are preferably in the following ranges, respectively. The crystalline resin sheet is a sheet having higher transparency as the haze is lower. The total haze is preferably 4% or less, more preferably 3.5% or less, further preferably 3% or less, and particularly preferably 2.5% or less. The internal haze is preferably 3% or less, more preferably 2.5% or less, further preferably 2% or less, and particularly preferably 1.5% or less. Here, the internal haze is the haze measured when the sheet surface is coated with liquid paraffin, and the total haze is the haze measured when the sheet surface is not coated with liquid paraffin and is not treated. Each haze is a value measured on a test piece with a sheet thickness of 400 μm in accordance with JIS K 7136. Although Examples and Comparative Examples are shown below, the present invention is not limited to the following Examples. [Example]

[0036] [Example 1] [Preparation of Resin Composition for Calendering] Isotactic polypropylene (iPP) (Mw = 32.6 × 10 4 , Mw / Mn=11.4, xylene soluble component (XS)=1.6wt%, stereoregularity (pentad: mmmm)=97.5%) as the resin material, 1.0wt% of a melt-type transparent nucleating agent (Millad NX8000 manufactured by Milliken of the nonanol series), 0.24wt% of an antioxidant (B225 manufactured by BASF) and 0.05wt% of a neutralizing agent (calcium stearate manufactured by Tamnan Chemical Industry Co., Ltd.) were mixed therein, and melt-kneaded at 230°C using an extruder to prepare a resin composition S for calendering.

[0037] The "Mw" of the resin material refers to the weight average molecular weight, and "Mn" refers to the number average molecular weight. As described below, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are measured, and the molecular weight distribution (Mw / Mn) is obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). PL GPC220 manufactured by Polymer Laboratories was used as an apparatus, 1,2,4-trichlorobenzene containing an antioxidant was used as a mobile phase, UT-G (1 root), UT-807 (1 root), and UT-806M (2 roots) manufactured by Showa Denko K.K. were connected in series and used as a column, and a differential refractometer was used as a detector. In addition, the same solvent as the mobile phase was used as a solvent for the sample solution, and the sample concentration of 1 mg / mL was prepared by dissolving it at a temperature of 150°C while shaking for 2 hours. 500 μL of the sample solution thus obtained was injected into the column and measured at a flow rate of 1.0 mL / min, a temperature of 145°C, and a data acquisition interval of 1 second. The column was calibrated by third-order approximation using polystyrene standard samples with molecular weights of 5.8 million to 7.45 million (shodex STANDARD, manufactured by Showa Denko K.K.). The Mark-Houwink-Sakurada coefficient was K = 1.21 × 10 -4 , α = 0.707, and for propylene polymers, K = 1.37 × 10 -4 ,α=0.75.

[0038] The xylene soluble fraction (XS) of the resin material is measured by a method in accordance with ISO 16152; First Edition; 2005-07-01. In addition, the NMR (JNM-GSX400 ( 13 The isotactic fraction (mmmm) in the meso pentad unit of the methyl group in the molecular chain, which is an index of the stereoregularity of the polypropylene polymer, was determined by measuring the C nuclear resonance frequency (100 MHz). The measurement conditions of NMR are as follows. Measurement mode: proton decoupling method, pulse width: 8.0 μs, pulse repetition time: 3.0 μs, cumulative number of times: 20,000 times, solvent: a mixed solvent of 1,2,4-trichlorobenzene (75 volume %) / heavy benzene (25 volume %), internal standard: hexamethyldisiloxane, sample concentration: 300 mg / 3.0 ml solvent, measurement temperature: 120°C It should be noted that each signal was assigned based on the description of A. Zambelli et al., Macromolecules, 13, 267, 1980.

[0039] The crystallization temperature (Tc) of the crystalline resin rolled with the nip rolls and the melting point (Tm) of the crystalline resin were measured by DSC. The measurement conditions were the following measurement device, sample mass, and measurement temperature mode. Measurement device: Diamond DSC manufactured by PerkinElmer Sample mass: approximately 5 mg Measurement temperature mode: (1) hold at 230°C for 5 minutes, (2) cool at 10°C / min and measure the temperature of the top of the crystallization peak (Tc). (3) hold at 30°C for 10 minutes, (4) heat at 10°C / min and measure the temperature of the top of the melting peak (Tm).

[0040] [Molding of polypropylene sheets] use Figure 1 The opposed roll sheet forming machine schematically shown in the figure is used to press and stretch the melt of the calendering resin composition S between a pair of metal nip rolls to form a sheet with an average thickness of 169 μm. The molding conditions are as follows: the temperature (Te) of the resin composition immediately before calendering of S is 199°C, the nip roll temperature (Tr) is 120°C, and the pulling speed (V) is 9 m / min. The average elongation strain rate ε of MD during molding is 33s -1 . Other molding conditions are shown in Table 1. The "nip roll" in Table 1 refers to the Figure 1 The extruder shown has two rollers. The "die lip gap ( Figure 1 The “lip gap” in Table 1 refers to the width of the slit-shaped opening (slit width) of the die head that ejects the molten resin composition. The “gelling agent” in Table 1 refers to a melt-type nucleating agent.

[0041] A multipurpose test piece of type A2 specified in JIS K7139 was machined from a sheet having a thickness of 169 μm obtained by molding, and the tensile modulus and tensile strength were measured under the conditions of a temperature of 23° C., a relative humidity of 50%, and a test speed of 1 mm / min using a precision universal testing machine (Autograph AG-X 10 kN) manufactured by Shimadzu Corporation in accordance with JIS K7161-2.

[0042] [Example 2] and [Comparative Example 1] Sheets were molded and evaluated in the same manner as in Example 1 except that the molding conditions shown in Table 1 were used by using the calendering resin composition S.

[0043] In order to observe the three-dimensional crystal structure of the formed sheet, the obtained sheet was observed with a polarizing microscope and measured with X-ray diffraction in the ND, TD, and MD directions (perspective view, edge view, and end view, respectively). Polarized light microscopy observation was performed under crossed Nicol prisms using a sensitive color plate (scp). X-ray diffraction was measured using X-rays (wavelength = 0.15 nm, ), SAXS and WAXD were measured to obtain a two-dimensional pattern. PILATUS was used as the detector for SAXS, and the measurement was performed with a camera length of approximately 3 m and an exposure time of 3 seconds. SOPHIAS was used as the detector for WAXD, and the measurement was performed with a camera length of approximately 5 cm and an exposure time of 3 seconds.

[0044] [Evaluation of polypropylene sheets] exist Figure 2 No spherulites were observed at the resolution (approximately 1 μm) of the polarizing microscope photograph of Example 2 shown. The extinction angle is purple-red in all observation directions, showing optical isotropy (a, c, e). On the other hand, if MD is placed parallel to the sensitive color plate (scp), the optical anisotropy is maximum in the perspective view, but it is a mottled pattern together with (b) and the edge view (d). If TD is placed parallel to the sensitive color plate, it is isotropic in the end view (f). This suggests that the c-axis is oriented mainly in the elongation direction (MD) and that there are isotropic crystals (NC; Nano crystal) that constitute NOC. Figure 3 The SAXS pattern of Example 2 shown in the perspective view and edge view shows a one-dimensional and two-dimensional two-point image and a ring pattern (a, b) on the MD, and shows central dispersion scattering (c) in the end view. Thus, the generation of NOC (NC arranged in the MD as the main body and isotropic in orientation) was confirmed. According to these measurement results, when the average elongation strain rate ε is 73s -1 NOC is generated when the critical elongation strain rate ε* in the manufacturing method of this embodiment is less than 73s -1 This value is significantly smaller than the value of the critical elongation strain rate ε* (200 s -1 ). In addition, the average size of NC calculated using a two-point image of SAXS according to the description in Non-Patent Document 1 is approximately 20 nm. Figure 4The WAXD pattern of Example 2 shown shows that the c-axis is highly oriented in the MD in perspective and edge views (a, b), and shows a ring-like pattern in the end view (c). Thus, the generation of NOC (aligned in the MD) was verified. In addition, the tensile elastic modulus and tensile strength are shown in Table 1. According to the above evaluation results, according to the manufacturing method of Example 2, the crystalline resin composition contains a melt-type nucleating agent, so even at a lower elongation strain rate than before, NOC can be generated, and a polypropylene sheet with high mechanical strength can be manufactured. In addition, as shown in Table 1, for Comparative Example 1, the SAXS pattern also shows a two-point image oriented in the MD, which shows that even at 30s -1 The following elongation strain rates also include NOC, but if the elongation strain rate exceeds 30s -1 By manufacturing at an elongation strain rate of , a highly oriented NOC in the MD can be generated, and through the 3D grid of the molten nucleating agent, a more complete NOC with isotropic NC three-dimensional connection can be formed, which can produce polypropylene sheets with dramatically improved mechanical properties.

[0045] [Table 1]

Claims

1. A method for producing a crystalline resin sheet, comprising: sandwiching a sheet-like crystalline resin composition in a molten state between a pair of nip rolls and rolling the sheet-like crystalline resin composition, wherein: The crystalline resin composition comprises a crystalline resin and a melt-type nucleating agent. When the radius of the pair of nip rollers is R, the average thickness of the rolled sheet is L, and the sheet pulling speed in the pair of nip rollers is V, The average elongation strain rate ε(R, L, V) in the sheet elongation direction represented by the following formula (1) is greater than 30 s -1 And 80s -1 Adjust in the following way. [Number 1] 2. The method for producing a crystalline resin sheet according to claim 1, wherein The crystalline resin composition in a sheet form in a molten state is obtained by discharging the crystalline resin composition from a die having a slit-shaped opening.

3. The method for producing a crystalline resin sheet according to claim 1 or 2, wherein: The rolled sheet is peeled off from the nip roll, and gas is sprayed toward a portion of the rolled sheet separated from the nip roll.

4. The method for producing a crystalline resin sheet according to claim 1, wherein The peripheral surface of at least one of the pair of nip rollers is subjected to a mold release treatment in advance.

5. The method for producing a crystalline resin sheet according to claim 1, wherein The temperature of the crystalline resin composition immediately before rolling is set to T e , the temperature of the pair of clamping rollers is set to T r The crystallization temperature of the crystalline resin composition measured by DSC is defined as T c , set the melting point to T m hour, By adjusting the temperature T e and the temperature T r , so that (T e -T m ) is in the range of -15°C to 130°C, and (T c -T r ) value ranges from -10℃ to 130℃.

6. The method for producing a crystalline resin sheet according to claim 1, wherein The temperature of the crystalline resin composition immediately before rolling is set to T e , the temperature of the pair of clamping rollers is set to T r The crystallization temperature of the crystalline resin composition measured by DSC is defined as T c , set the melting point to T m hour, By adjusting the temperature T e and the temperature T r , so that (T e -T m ) is in the range of 0℃~90℃, and (T c -T r ) value ranges from 0℃ to 110℃.

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