JP4917978B2 - Manufacturing method of polyolefin resin sheet and manufacturing apparatus used therefor - Google Patents

Description

  The present invention relates to a method for producing a polyolefin resin sheet having excellent mechanical strength such as transparency, tensile strength, and tensile modulus, and a production apparatus used therefor.

  Polyolefin resins such as polyethylene resin and polypropylene resin are thermoplastic, and in order to manufacture the sheet, generally, a method is adopted in which the polyolefin resin is melt-extruded into a sheet shape, and is brought into close contact with a cooling roll and rapidly solidified. .

  However, since the polyolefin resin is a crystalline resin, it is crystallized when the melted polyolefin resin sheet is rapidly cooled. However, when the polyolefin resin sheet is thick, the crystallization does not proceed uniformly and distortion occurs. In addition, the transparency and tensile strength of the polyolefin-based resin sheet, and the mechanical strength such as tensile elastic modulus may be insufficient.

In order to improve these, the melt-extruded sheet was brought into close contact with a rotating cooling roll by static electricity, an air knife, a metal roll, a rubber roll, a belt, etc., and an air knife, air and water mist were mixed with the film on the opposite roll surface. At a position where the sheet temperature on the roll is within the range of the melting point of the resin or less and the maximum crystallization speed temperature or more, the refrigerant is sprayed or the roll is immersed in the water tank (see, for example, Patent Document 1). A method of discharging the refrigerant from the refrigerant discharge die to the anti-roll surface, causing the refrigerant to flow down in a film form on the sheet at a flow rate and amount that does not boil or evaporate on the sheet surface, and cooling from the anti-roll surface (for example, However, the mechanical strength such as transparency, tensile strength, and tensile modulus may still be insufficient.
JP-A-62-214921 JP-A-10-128828

  In view of the above problems, an object of the present invention is to provide a method for producing a polyolefin resin sheet having excellent mechanical strength such as transparency, tensile strength, and tensile modulus, and a production apparatus used therefor.

Process for producing a polyolefin resin sheet of the present invention, after cooling in contact with the cooling roll being set polyolefin resin sheet which is melt-extruded at a temperature of 30 ° C. or less, the cooled polyolefin resin sheet highly upper and lower movable guide roll for adjusting relative heat treatment roll being heated to a temperature of the melting point (Tm) of the Vicat softening temperature - the polyolefin resin of said polyolefin resin is, downstream of the guide roll The guide roll installed on the heat treatment roll and the guide roll provided in parallel with the heat treatment roll, and the cooled polyolefin resin sheet placed in order on the heat treatment roll. And between the heat treatment roll and the cooled polyolefin-based resin sheet The characterized by heat treatment directly pressure-bonded by pressing in the heat treatment roll by the guide roll is parallel in the heat treatment roll.

  The polyolefin resin used in the present invention is a homopolymer or copolymer of crystalline olefin, for example, polyethylene resin, polypropylene resin, polybutene resin, polypentene resin, polyhexene resin, ethylene-propylene copolymer. For example, ethylene-butene-1 copolymer, ethylene-pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-4-methyl-pentene-1 copolymer, and the like. preferable.

  In the present invention, first, the melt-extruded polyolefin resin sheet is cooled by being brought into contact with a cooling roll set at a temperature of 30 ° C. or lower. The polyolefin resin sheet may be melt-extruded by any conventionally known method. For example, the polyolefin resin is melt-kneaded at a temperature equal to or higher than the melting point (Tm) of the polyolefin resin with an extruder. The method of extruding is mentioned.

  The thickness and extrusion rate of the polyolefin resin sheet are not particularly limited, but are preferably 0.01 to 0.7 mm, more preferably 0.1 to 0.00 mm in order to efficiently perform cooling and heat treatment. 5 mm. The extrusion rate of the polyolefin resin sheet varies depending on its thickness, but is preferably 1 to 20 m / min, and more preferably 1 to 5 m / min in order to efficiently perform cooling and heat treatment.

  Since the cooling roll is a roll for cooling the melt-extruded polyolefin resin sheet, it must be set to 30 ° C. or less, and preferably 10 to 30 ° C. There may be one cooling roll or a plurality of cooling rolls.

  When the melt-extruded polyolefin resin sheet is quenched, the polyolefin resin will crystallize, but the transparency and mechanical strength will decrease due to the mixture of smectic crystal and alpha crystal and the apparent crystallinity will not improve. Therefore, in the present invention, the cooled polyolefin resin sheet is heat-treated by being brought into contact with a heat treatment roll heated from the bigat softening temperature of the polyolefin resin to the melting point (Tm) of the polyolefin resin. In addition, the Vicat softening temperature in this invention is the Vicat softening temperature measured by the method of JISK7206.

  If the temperature of the heat treatment roll is too low, the change from smectic crystal to alpha crystal does not proceed efficiently, so the mixture of different crystal forms and apparent crystallinity do not increase, so transparency and mechanical strength are increased. If it is not improved and is too high, the polyolefin resin sheet melts. On the other hand, if the temperature of the heat treatment roll is too low, the effect of smoothing the surface of the cooled polyolefin resin sheet is lowered. Accordingly, the temperature of the heat treatment roll is from the bigat softening temperature of the polyolefin resin to the melting point (Tm) of the polyolefin resin, and preferably 100 to 120 ° C. in the case of the polypropylene resin. There may be one heat treatment roll or a plurality of heat treatment rolls.

  The heat treatment time is not particularly limited, but if it is too short, the effect of heat treatment is lost, and therefore it is preferably 10 seconds or longer, and the longer the treatment time, the better. Accordingly, the polyolefin resin sheet may be set so as to be in contact with the heat treatment roll for 10 seconds or longer. However, in order to make contact with the heat treatment roll for a long time, it is necessary to increase the diameter of the heat treatment roll or increase the number of heat treatment rolls. So it's not practical.

  In the method for producing a polyolefin resin sheet of the present invention, the heat-treated polyolefin resin sheet is further lower than the heat treatment temperature and the melting point (Tm) of the polyolefin resin to 60 ° C. to the melting point (Tm) of the polyolefin resin. It is preferable that the annealing is performed in contact with a set annealing roll. In the case of a polypropylene resin, 90 to 115 ° C is preferable.

  Annealing is a process to relieve the stress generated in the polyolefin resin sheet by heat treatment. When the annealing temperature is lowered, the stress relaxation effect is reduced, and when it is higher, it becomes the same as the heat treatment. The temperature is lower than the temperature and the melting point (Tm) of the polyolefin resin is set to −60 ° C. to the melting point (Tm) of the polyolefin resin, and is brought into contact with the annealing roll. The annealing time is not particularly limited and is generally 10 seconds or longer, more preferably 15 to 60 seconds, although it varies depending on the thickness of the polyolefin resin sheet and the annealing temperature. There may be one annealing roll or a plurality of annealing rolls.

  The apparatus for producing a polyolefin resin sheet according to claim 6 is an extruder for melt-extruding a polyolefin resin into a sheet shape, a cooling system installed at a downstream side of the extruder and set to a temperature of 30 ° C. or lower. A roll is provided on the downstream side of the cooling roll, and the heating roll is heated from the Vicat softening temperature of the polyolefin resin to the melting point (Tm) of the polyolefin resin.

  As the above-mentioned extruder, any conventionally known extruder used in the extrusion molding of thermoplastic resins can be used. For example, a single-screw extruder, a twin-screw extruder, and the like can be used. It is melt-kneaded at a temperature equal to or higher than the melting point (Tm) and melt extruded into a sheet to obtain a polyolefin resin sheet.

  The cooling roll is a roll installed on the downstream side of the extruder and for cooling the polyolefin resin sheet extruded from the extruder to a temperature of 30 ° C. or lower, and is cooled to a temperature of 30 ° C. or lower. .

  The cooling roll is preferably provided with a crimping device in order to uniformly contact and crimp the polyolefin resin sheet to the cooling roll. Examples of the crimping device include a roll, a metal belt, an air knife, and an electrostatic crimping device. Apparatus and the like.

  The heat treatment roll is installed on the downstream side of the cooling roll, and heat-treats the cooled polyolefin resin sheet by heating to a temperature between the Vicat softening temperature of the polyolefin resin to the melting point (Tm) of the polyolefin resin. It is a roll.

  The heat treatment roll is preferably provided with a guide roll for pressure-bonding so that the polyolefin resin sheet is in uniform contact with the heat treatment roll. It is preferable that the polyolefin resin sheet is pressed against the heat treatment roll for the first time by pressing the polyolefin resin sheet cooled by the guide roll. That is, if the polyolefin resin sheet is not simultaneously and uniformly pressed on the heat treatment roll (if a part of the polyolefin resin sheet is floating), the heat treatment speed of the polyolefin resin is different and flare occurs to obtain a uniform sheet. No guide roll is installed in the direction perpendicular to the polyolefin resin sheet feed direction. The guide roll presses the polyolefin resin sheet in the heat treatment roll direction so that the polyolefin resin sheet contacts the heat treatment roll for the first time. It is preferable to crimp.

  The temperature of the heat treatment roll is from the Vicat softening temperature of the polyolefin resin to the temperature of the melting point (Tm) of the polyolefin resin, from the glass transition temperature (Tg) of the polylactic acid resin to the melting point (Tm) of the polylactic acid resin. Although what is necessary is 100-120 degreeC in the case of a polypropylene resin.

Further, the ratio R _{2 /} R ₁ of the diameter of the so towards the time required for the heat treatment than the time required for cooling is long and the diameter R ₂ of the heat treatment roll cooling roll R ₁ is preferably as large, too larger is impractical 1 to 20 is preferable, and 1.2 to 7 is more preferable.

  In the polyolefin resin sheet production apparatus of the present invention, the heat treated polyolefin resin sheet is further lower than the heat treatment temperature and the melting point (Tm) of the polyolefin resin to 60 ° C. to the melting point (Tm) of the polyolefin resin. It is preferable that a set annealing roll is installed.

  The annealing roll is a roll for relieving the stress generated in the polyolefin resin sheet by the heat treatment. When the annealing temperature is lowered, the stress relaxation effect is reduced. It is preferable that the temperature is lower than the heat treatment temperature and the melting point (Tm) of the polyolefin resin is set to −60 ° C. to the melting point (Tm) of the polyolefin resin. Although there may be one annealing roll or a plurality of annealing rolls, although the annealing time varies depending on the thickness of the polyolefin resin sheet and the annealing temperature, it is generally preferably 10 seconds or more, more preferably 15 to 60 seconds. Therefore, it is preferable to install a plurality of small-diameter annealing rolls continuously.

  Next, an example of the apparatus for producing a polyolefin resin sheet of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an example of an apparatus for producing a polyolefin resin sheet of the present invention. In the figure, 1 is an extruder, and 2 is a T die connected to the discharge port of the extruder 1 for extruding a sheet. Cooling rolls 3 and 31 set to a temperature of 30 ° C. or lower are installed in front of the lower side of the T die 2. An electrostatic pressure bonding device 4 is installed facing the cooling roll 3 so that the high-temperature polyolefin-based resin sheet 10 supplied from the T die 2 can be pressure bonded to the cooling roll 3.

  8 and 81 are heat treatment rolls heated from the Vicat softening temperature of the polyolefin-based resin to the melting point (Tm) of the polyolefin-based resin, and the guide roll 7 is installed facing the heat treatment roll 8. The guide roll 7 is biased so that the polyolefin resin sheet 11 cooled by the cooling rolls 3 and 31 can be pressed against the heat treatment roll 8 with a constant pressure. Therefore, the polyolefin resin sheet 11 is pressed against the heat treatment roll 8 for the first time by pressing the cooled polyolefin resin sheet 11 against the heat treatment roll 8 with the guide roll 7.

  Nos. 9 and 91 are annealing rolls for annealing the polyolefin resin sheet 12 installed on the downstream side of the heat treatment roll 81 and heat-treated. The annealing roll is lower than the heat treatment temperature and has a melting point (Tm) of −60 ° C. to polyolefin The melting point (Tm) of the resin is set. The heat-treated polyolefin resin sheet 12 is annealed by the annealing rolls 9 and 91 to obtain a polyolefin resin sheet 13 in which the stress generated in the polyolefin resin sheet is relaxed by the heat treatment.

  5, 51, 52 are guide rolls for sending the polyolefin resin sheets 11, 12, 13 downstream, and 6 is a vertically movable type for adjusting the height of the polyolefin resin sheet 11 with respect to the heat treatment roll 8. It is a guide roll. The cooling rolls 3 and 31, the heat treatment rolls 8 and 81, the annealing rolls 9 and 91, the guide rolls 5, 6, 7, 51, 52 and the electrostatic pressure bonding device 4 are made of polyolefin resin sheets 10, 11, 12, 13. It is installed so as to be perpendicular to the feed direction.

  In the extruder 1, the polyolefin resin is melt-kneaded at a temperature equal to or higher than the melting point (Tm) of the polyolefin resin, and melted and extruded from the T die 2 into a sheet to obtain a melted polyolefin resin sheet 10. Next, the polyolefin resin sheet 10 which has been melted is pressure-bonded to the cooling roll 3 by the electrostatic pressure bonding device 4, and the polyolefin resin sheet 10 is rapidly cooled to a temperature of 30 ° C. or less by the cooling rolls 3 and 31. A system resin sheet 11 is obtained.

  Next, the cooled polyolefin resin sheet 11 is sent to the downstream side by the guide rolls 5, 6, 7 and supplied to the heat treatment roll 8. The cooled polyolefin resin sheet 11 is uniformly pressure-bonded to the heat treatment roll 7 by the guide roll 7, and the polyolefin resin sheet 11 cooled by the heat treatment rolls 8 and 81 is subjected to the Vicat softening temperature of the polyolefin resin to the polyolefin resin. Heating to the temperature of melting | fusing point (Tm) and heat-processing polyolefin resin, and the heat-treated polyolefin resin sheet 12 is obtained.

  Since the polyolefin resin sheet 11 is uniformly pressure-bonded to the heat treatment roll 8 so as to be in contact with the heat treatment roll 8 for the first time by the guide roll 7, the polyolefin resin sheet 11 is uniformly heated in the width direction and flare does not occur. Heat treated uniformly and there is no variation in transparency of the entire sheet.

  The annealed roll which is heat-treated polyolefin resin sheet 12 is sent to the downstream side by guide roll 52, and is set to a melting point (Tm) -60 ° C. of polyolefin resin to a melting point (Tm) of polyolefin resin lower than the heat treatment temperature. By annealing at 9 and 91, the polyolefin resin sheet 13 in which the stress generated in the polyolefin resin sheet by heat treatment is relaxed is obtained.

  The structure of the manufacturing method of the polyolefin resin sheet of this invention is as above-mentioned, and can manufacture the polyolefin resin sheet excellent in mechanical strength, such as transparency, tensile strength, and a tensile elasticity modulus. In addition, the configuration of the polyolefin resin sheet production apparatus of the present invention is as described above, and is used to continuously produce a polyolefin resin sheet having excellent mechanical strength such as transparency, tensile strength, and tensile elastic modulus. It can be preferably used.

Next, examples of the present invention will be described, but the present invention is not limited to the following examples.
Example 1
A polypropylene resin sheet was produced using the production apparatus shown in FIG. The extruder 1 is a uniaxial extruder with a diameter of 70 mm, melt-kneaded polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., trade name “FH1051”, Tm = about 160 ° C., Vicat softening temperature = 62 ° C.) at 240 ° C. A melted polyolefin resin sheet 10 having a thickness of 0.2 mm was extruded.

  The diameter of the cooling rolls 3 and 31 was 300 mm, and it was cooled to 10 ° C. The contact distance of the melted polyolefin resin sheet 10 to the cooling rolls 3 and 31 was about 1 m. The molten polyolefin resin sheet 10 is supplied to the cooling rolls 3 and 31 at a speed of 3 m / min (the contact time of the molten polyolefin resin sheet 10 with respect to the cooling rolls 3 and 31 is 20 seconds) and is cooled to about 15 ° C. A polyolefin resin sheet 11 was obtained.

  The diameters of the heat treatment rolls 8 and 81 were 600 mm and heated to 120 ° C. The contact distance of the cooled polyolefin resin sheet 11 with respect to the heat treatment rolls 8 and 81 was about 1 m. The cooled polyolefin resin sheet 11 is heat-treated with heat treatment rolls 8 and 81 (the contact time of the cooled polyolefin resin sheet 11 with respect to the heat treatment rolls 8 and 81 is 40 seconds), and the heat-treated polyolefin resin sheet 12 is Obtained.

  Annealing rolls 9 and 91 had a diameter of 600 mm and were heated to 115 ° C. The heat-treated polyolefin resin sheet 12 was sent in the downstream direction by the guide rolls 51 and 52 and annealed by the annealing rolls 9 and 91 to obtain the annealed polyolefin resin sheet 13.

(Comparative Example 1)
An annealed polyolefin resin sheet 13 was obtained in the same manner as in Example 1 except that the temperature of the heat treatment rolls 8 and 81 was changed to room temperature (about 23 ° C.).

The obtained polyolefin resin sheet 13 was measured for tensile strength, elongation, tensile modulus, haze, and total light transmittance, and the results obtained are shown in Table 1. The tensile strength, elongation, and tensile modulus of elasticity were obtained by punching a test piece type No. 5 test piece in the MD direction in accordance with JIS K 7127 and conducting a tensile test at a speed of 200 mm / min. Moreover, haze and total light transmittance are measured according to JIS.
Measurement was performed using an integrating sphere light transmittance measuring device (haze meter) in accordance with K 7105.

It is explanatory drawing which shows an example of the manufacturing apparatus of the polyolefin resin sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 T die 3 Cooling roll 4 Electrostatic pressure bonding apparatus 5, 6, 7 Guide roll 8 Heat treatment roll 9 Annealing roll 10, 11, 12, 13 Polyolefin resin sheet

Claims (5)

After the melt-extruded polyolefin resin sheet is brought into contact with a cooling roll set at a temperature of 30 ° C. or lower and cooled , the height of the cooled polyolefin resin sheet is set to the Vicat softening temperature of the polyolefin resin to the A vertically movable guide roll for adjusting the heat treatment roll heated to the temperature of the melting point (Tm) of the polyolefin resin, and a guide installed on the downstream side of the guide roll and attached to the heat treatment roll After the cooled polyolefin resin sheet is passed over the roll in order, the cooled polyolefin resin sheet is supplied between the heat treatment roll and the guide roll provided side by side with the heat treatment roll, The guide roll in which the cooled polyolefin resin sheet is attached to the heat treatment roll. Therefore directly pressed to the heat treatment roll, a polyolefin resin sheet manufacturing method which is characterized in that a heat treatment by crimping. Furthermore, annealing is performed by bringing the heat-treated polyolefin resin sheet into contact with an annealing roll that is lower than the heat treatment temperature and set to the melting point (Tm) of the polyolefin resin to 60 ° C. to the melting point (Tm) of the polyolefin resin. The method for producing a polyolefin resin sheet according to claim 1. 3. The method for producing a polyolefin resin sheet according to claim 1, wherein the polyolefin resin is a polypropylene resin. The method for producing a polyolefin resin sheet according to any one of claims 1 to 3, wherein the temperature of the heat treatment roll is 100 to 120 ° C. The method for producing a polyolefin resin sheet according to any one of claims 1 to 4, wherein a contact time between the heat treatment roll and the polyolefin resin sheet is 10 seconds or more.

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