JP4464582B2 - Resin sheet manufacturing method and resin sheet molding casting apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, for example, a molten resin extruded from a T-die is securely attached to a cooling roll using a suction chamber device, and a film-like or sheet-like resin thin film (hereinafter referred to as an excellent surface gloss, transparency, etc.) And a casting apparatus used therefor.
[0002]
[Prior art]
In the film manufacturing apparatus for forming a sheet by winding the molten resin extruded from the T die around a rotating cooling roll, in order to keep the molten resin in good contact with the cooling roll surface, the molten resin is about to land on the cooling roll surface. The conventional structure of the suction chamber device for preventing air from being caught between the molten resin and the cooling roll is as shown in the side sectional view of FIG. 3 and the perspective view of FIG. In FIG. 3, 1 is a T-die of an extruder, 2 is a cooling roll, 3 is a resin sheet extruded in a sheet shape, 3a is a molten resin, 010 is a suction chamber device, and a main body 011 of the suction chamber device 010 is The wall on the cooling roll 2 side is removed, the suction port 011b is opened on the resin sheet 3 side, and a linear seal packing 015 is attached on the upper side of the suction port 011b. The air mixed with the additive volatile component gas contained in the resin sheet 3 sucked from the suction port 011b is sucked from the suction port 014 through the piping hose 018 by a suction blower (not shown).
[0003]
In the conventional example disclosed in Japanese Patent Application Laid-Open No. 11-188776, since the temperature of the inner wall of the suction chamber as described above is low, the volatile component of the additive condenses and accumulates on the inner wall surface, so that the two cooling roll surfaces In order to prevent the product sheet from falling and contaminating the product sheet, a heater, temperature sensor, temperature controller, etc. are provided to heat the inner wall surface of the suction chamber so as to keep the temperature of the inner wall surface of the suction chamber above a certain temperature. Yes.
[0004]
Further, in the conventional example disclosed in Japanese Patent Laid-Open No. 2000-225624, the temperature of the inner wall surface of the suction chamber is maintained at a high temperature by a configuration in which the suction chamber is integrated with the T die or integrally fixed to the T die. In this way, it is a means for preventing volatile components from the molten resin from condensing on the inner wall surface.
[0005]
[Problems to be solved by the invention]
In the conventional suction chamber device 010 having a separate structure, the temperature of the inner wall surface becomes low as described above, so that the volatile component from the additive of the molten resin condenses on the upper wall surface 011a, and the surface of the cooling roll 2 There is a problem that the cooling roll 2 is dropped and the resin sheet 3 is stained and the quality of the product sheet is deteriorated. The conventional example of Japanese Patent Application Laid-Open No. 11-188777 proposed for solving this problem can prevent the volatile component from condensing on the inner wall surface of the suction chamber, but the heater for heating the inner wall surface The temperature controller is expensive.
[0006]
In addition, the structure of the T-die and the suction chamber integrated in the conventional example disclosed in Japanese Patent Laid-Open No. 2000-225624 proposed for solving the same problem is that the inner wall surface on the T-die side is kept at a high temperature. Since the temperature of the lower and rear inner wall surfaces decreases, the additive volatilized from the molten resin condenses on the inner wall surface and becomes contaminated, and the point that the accumulated condensate falls on the surface of the cooling roll 2 is unresolved. In addition, it is difficult to clean the inner wall surface.
[0007]
In the sheet manufacturing apparatus, when a molten resin is wound around a rotating cooling roll and formed into a sheet shape, the suction chamber sucks air between the molten resin and the cooling roll into the molten resin cooling roll. In addition to improving the adhesion of the resin, low molecular weight components contained in the molten resin, volatile components from additives, etc. are prevented from condensing on the inner wall surface of the suction chamber, preventing contamination of the cooling roll surface, surface gloss, It is an object of the present invention to provide a method for producing a resin sheet having improved quality such as transparency, and a suction chamber having a relatively inexpensive structure suitable for the method.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a resin sheet manufacturing method in which a molten resin extruded from a die is cooled and solidified on a cooling surface that moves in a predetermined direction, from the point of dropping of the molten resin to the cooling surface. A suction chamber body disposed upstream in the direction and having a suction space to which a lower surface of the die is exposed; a lower surface of the die; and an edge of a U-shaped opening near the lower surface of the die of the suction chamber body; A heat-resistant U-shaped seal packing interposed therebetween, and a receiving plate that contacts the back side wall opposite to the die opening of the suction chamber body and faces the cooling surface over the entire width of the suction chamber body in preparative and the provided plurality of suction port communicating with the suction space, a suction outlet manifold pipe coupling the suction blower and the suction outlet, provided in the path of the suction air in the suction space and the perforated plate Solving the problem by a method for producing a resin sheet, characterized in that the suction chamber device is configured to suck the air between the cooling surface and the molten resin to bring the molten resin into close contact with the cooling roll surface and solidify by cooling. Means.
The present invention also provides a casting apparatus for molding a resin sheet in which a molten resin extruded from a die is cooled and solidified on a cooling surface moving in a predetermined direction to form a resin sheet, toward the molten resin extruded from the die. A suction chamber body that is open and leaves the side wall and the bottom wall facing the cooling surface and the top wall contacting the bottom surface of the die; and the bottom surface of the die and the bottom surface of the suction chamber body close to the bottom surface of the die. A heat-resistant U-shaped seal packing interposed between the edges of the U-shaped opening and the back side wall of the suction chamber body opposite to the die port and over the entire width of the suction chamber body. It provided a receiving plate facing the cooling surface, and a plurality of suction outlet, a suction blower and piping coupled suction outlet manifold, provided in the path of the suction air of the suction chamber body The resin sheet forming a casting apparatus characterized by comprising a suction chamber apparatus which is composed of a perforated plate and means for solving problems.
Furthermore, the present invention provides a casting apparatus for molding a resin sheet in which a molten resin extruded from a die is cooled and solidified on a cooling surface moving in a predetermined direction to form a resin sheet, toward the molten resin extruded from the die. A suction chamber body that is open and leaves the side wall and the bottom wall facing the cooling surface and the top wall contacting the bottom surface of the die; and the bottom surface of the die and the bottom surface of the suction chamber body close to the bottom surface of the die. A heat-resistant U-shaped seal packing interposed between the edges of the U-shaped opening, and the upper side of the suction air passage of the suction chamber body is heated by heat from the die, and a plurality of suction A suction chamber device comprising: an outlet, a suction manifold connected to a suction blower by piping, and a perforated plate provided in a suction air passage of the suction chamber body. The resin sheet for molding a casting apparatus characterized by been example a means of solving the problems.
[0009]
In the present invention described above, it is desirable that the resin is a polyolefin, and the polyolefin is a linear low density polyethylene .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a resin sheet molding casting device and its periphery, and FIG. 2 is a perspective view of the suction chamber device of FIG. Since the extruder T-die, the cooling roll, and the resin sheet extruded in a sheet form have the same configuration as the above-described conventional example, the same reference numerals are used in the following description.
[0011]
1 and 2, 1 is a T-die of an extruder for extruding molten resin 3a into a sheet shape, 2 is a molten resin 3a extruded from T-die 1 on the outer peripheral surface, cooled and solidified to the next processing step. This is a cooling roll to be sent out. As the cooling roll 2 rotates, the cooling surface moves in a predetermined direction.
The suction chamber device 10 includes a heat-resistant body interposed between a suction chamber main body 11, a lower surface of the T die 1, and an edge of the U-shaped opening near the lower surface of the T die 1 of the suction chamber main body 11. A U-shaped seal packing 16, a suction outlet manifold 19, a plurality of suction outlets 14 provided in the suction chamber body 11 and a plurality of suction pipe manifolds 19, and a plurality of vacuum piping hoses 18; The suction blower 5 is connected to the manifold 19 by piping.
[0012]
The suction chamber body 11 is arranged on the upstream side in the moving direction of the cooling surface by the rotation of the cooling roll 2, and the upper plate 11a from which the side close to the T die 1 is removed, side walls 11b and 11c, and the back plate 11d. And the structure which the some suction port 14 integrated, makes the half box shape by which the lower side which faced the cooling roll 2 was open | released. A receiving plate 12 and a porous plate 13 are provided on the back plate 11d and the side walls 11b and 11c. A portion surrounded by the lower surface of the T die 1, the circumferential surface of the cooling roll 2, and the tips of the side walls 11 b and 11 c forms a suction space having a suction port 9 and a suction air passage. The lower surface of the T die 1 is exposed to this suction space.
A U-shaped seal packing 16 is formed by the seal packing 15 at the edge of the upper plate 11a of the suction chamber body 11 and the seal packing 15a at the upper edges of the side walls 11b and 11c. When the suction chamber body 11 is fixed at a predetermined position, the lower edges of the side walls 11b and 11c and the back plate 11d are arranged so that excessive air does not enter the suction chamber body 11 during suction. , And adjusted to a position away from the cooling roll 2 by a slight distance (1-2 mm). Reference numeral 17 denotes a rectifying guide plate provided on both sides of the T die 1 for preventing the stagnation of the intake air.
[0013]
When the molten resin 3a is extruded from the T-die 1 into a sheet shape and wound around the cooling roll 2 rotating at a peripheral speed synchronized with the sheet speed, the molten resin 3a is brought into close contact with the surface of the cooling roll 2 A suction force is applied from the suction port 9 to prevent air from being caught between the cooling roll 2 and the cooling roll 2. The sucked air is sucked out by the suction blower 5 from the suction port 14 of the suction chamber device 10 through the hose 18 and the suction port manifold 19. The air sucked in this way is mixed with gas of volatile components from low molecular weight components, additives and the like contained in the resin sheet 3.
[0014]
This volatile component gas is likely to condense when the temperature is lowered. In the case of the conventional case shown in FIG. 3, the temperature of the upper wall surface 011a is lowered. When a certain amount accumulates, it drops and contaminates the cooling roll 2, resulting in a problem that the surface of the resin sheet 3 facing the cooling roll 2 is contaminated. However, unlike the suction chamber main body 11 of the present embodiment, there is no upper plate portion of the housing, and the lower surface of the T die 1 sealed with the seal packings 15 and 16 is exposed to the suction space formed in the suction chamber main body 11. The T die 1 is heated by heating means (not shown) in order to melt the resin. Therefore, there is no possibility that the gas of the volatile component condenses in the portion.
[0015]
However, since the upper plate 11a on the back plate 11d side of the suction chamber body 11 is away from the T-die 1, the temperature is lowered, and there is a possibility that the gas of the volatile component condenses. Correspondingly, a receiving plate 12 is provided on the upper plate 11a of the main body 11 to receive a dripping liquid of the volatile component condensed into a liquid. The receiving plate 12 is provided so as to face the cooling roll 2 over the entire width of the suction chamber body 11.
Further, in order to make the suction air uniform, the piping divided by the suction outlet manifold 19 enters a plurality of suction outlets 14, and is further made uniform by the perforated plate 13.
[0016]
The resin according to the present invention is not particularly limited as long as it is a thermoplastic resin that can be formed into a sheet. Specific examples of such thermoplastic resins include homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, and the like. Polyethylene, linear low density polyethylene (so-called LLDPE), high density polyethylene, polypropylene, polypropylene random copolymer, polybutene, poly-4-methyl pentene-1, low crystalline or amorphous ethylene / propylene random copolymer , Ethylene / butene-1 random copolymer, polyolefin such as propylene / butene-1 random copolymer, or a composition of two or more kinds, ethylene / vinyl acetate copolymer (EVA), or composition of EVA and polyolefin , Polyethylene phthalate, polybutylene phthalate and poly Polyesters such as Chi naphthalate, nylon 6, nylon 66 and poly meta-xylene adipamide polyamide inorganic compounds such as bromide and (B) and thermoplastic resin such as polystyrene can be exemplified.
Among these thermoplastic resins, polyolefin is preferable, high-pressure method low-density polyethylene and linear low-density polyethylene are preferable, and linear low-density polyethylene is particularly preferable.
[0017]
The high-pressure low-density polyethylene usually has a density of 0.910 to 0.935 g / cm ³ , preferably 0.920 to 0.935 g / cm ³ , and MFR (ASTM D1238 load 2160 g, temperature 190 ° C.) 1 to 1. A homopolymer of ethylene polymerized under a high pressure of 30 g / 10 min, preferably 1 to 10 g / 10 min, or a copolymer with a vinyl compound such as 5 wt% or less of other α-olefin or vinyl acetate Can be used.
[0018]
The linear low density polyethylene usually has a density of 0.905 to 0.940 g / cm ³ , preferably 0.910 to 0.935 g / cm ³ , and MFR (ASTM D1238 load 2160 g, temperature 190 ° C.). 0.5 to 20 g / 10 minutes, preferably 1 to 10 g / 10 minutes of ethylene and an α-olefin having 3 to 10 carbon atoms, such as propylene, butene-1, heptene-1, hexene-1, octene-1, It is a random copolymer with 4-methyl-pentene-1. The linear low density polyethylene has a molecular weight distribution (weight average molecular weight: Mw, number average molecular weight: Mn, expressed as Mw / Mn) is usually 1.5 to 4.0, preferably 1. It is in the range of 8-3.5. This Mw / Mn can be measured by gel permeation chromatography (GPC).
[0019]
Linear low density polyethylene has one or more sharp peaks obtained from an endothermic curve measured at a heating rate of 10 ° C./min with a differential scanning calorimeter (DSC), and the maximum temperature of the peak, that is, the melting point. Is usually in the range of 70 to 130 ° C, preferably 80 to 120 ° C. The linear low density polyethylene as described above can be prepared by a conventionally known production method using a single site catalyst. For example, linear low density polyethylene can be prepared using a catalyst containing a metallocene compound of a transition metal. The catalyst containing the metallocene compound is preferably formed from (a) a transition metal metallocene compound, (b) an organoaluminum oxy compound, and (c) a carrier, and if necessary, these components and (D) It may be formed from an organoaluminum compound and / or an organoboron compound.
An olefin polymerization catalyst containing such a metallocene compound and a method for adjusting linear low density polyethylene using the catalyst are described, for example, in JP-A-8-269270.
The resin according to the present invention includes antioxidants, weathering stabilizers, ultraviolet absorbers, lubricants, nucleating agents, antistatic agents, antistatic agents, which are usually used in thermoplastic resins such as polyolefins, as long as the object of the present invention is not impaired. Various additives such as a clouding agent, an anti-blocking agent, a slip agent, a pigment, a dye, and an inorganic or organic filler can be blended as necessary.
[0020]
The resin sheet 3 obtained by the method of the present invention may be unstretched or may be used as a raw material for a uniaxially stretched sheet or a biaxially stretched sheet.
[0021]
〔Example〕
(Production example of sheet using linear low density polyethylene)
A linear low density polyethylene [density: 0.920 g / cm ³ , MFR: 4 g / 10 min, molecular weight] produced using a metallocene catalyst in an extruder using a casting apparatus equipped with the suction chamber apparatus 10 shown in FIG. Distribution (weight average molecular weight: Mw, ratio of number average molecular weight: Mn: Mw / Mn): 2.3, DSC melting point: main peak 118 ° C. (with secondary peaks at 105 ° C. and 122 ° C.)] Thereafter, the molten resin 3a is extruded from the T die 1, and the suction chamber device 10 sucks the air between the molten resin 3a and the cooling roll 2 in order to prevent air from being caught between the molten resin 3a and the cooling roll 2. Then, the resin sheet 3 having a thickness of 40 μm was manufactured after cooling and solidification while improving the adhesion. Although the resin sheet 3 was produced continuously for four days, no volatile components adhered to the surface of the resin sheet 3 even after four days, and the resin sheet 3 having excellent transparency was obtained.
Separately, when the suction chamber apparatus 10 was removed to produce a collinear low density polyethylene sheet, only the resin sheet 3 inferior in surface gloss, transparency and the like was obtained.
[0022]
【The invention's effect】
According to the method of the present invention, by using the suction chamber, the adhesion between the molten resin and the cooling surface is improved, the condensation of volatile components generated from the molten resin is prevented, and the volatile components are dropped onto the cooling surface. Therefore, it is possible to produce a resin sheet having excellent surface gloss, transparency and the like, and it has a feature that it can be produced for a long time. In particular, when linear low density polyethylene is used as the resin, the effect of improving such characteristics is remarkable. (Claims 1 to 3)
[0023]
In the present invention, when the molten resin extruded from the T-die of the casting apparatus for molding a resin sheet is cooled on the cooling surface, the molten resin and the cooling surface are sucked and depressurized to prevent air from being trapped therebetween. The suction chamber provided in order to improve the adhesion between the molten resin and the cooling surface is opened on the molten resin side, and the upper surface close to the lower surface of the die and the lower wall facing the cooling surface, leaving the side wall. Since the wall is removed and the space between the lower surface of the die and the edge of the U-shaped opening of the suction chamber is hermetically sealed with a U-shaped seal packing, the upper side of the suction air passage of the suction chamber is heated by the heat from the die. Prevents condensation of volatile components from low molecular weight components or additives generated from molten resin at high temperatures, and prevents the occurrence of defective resin sheet products by preventing dripping of volatile components on the cooling surface Door can be. Thus, there is an effect that the cleaning cycle becomes longer due to prevention and reduction of additive adhesion. The suction chamber die and it can be separated by seal packing portion, the opening portion is wide cleaning easy, the effect of improving production efficiency because it can be finished in a short time (claim 4).
[0024]
In the above suction chamber, since the dripping liquid receiving plate is provided over the entire width in contact with the wall on the back side of the suction chamber so as to face the cooling roll, the temperature is lowered because it is separated from the die of the suction air passage of the suction chamber. Even if the volatile component generated from the molten resin is condensed and dripped onto the upper side wall, the dripping liquid is received and the cooling surface is prevented from being contaminated, so that the same effect as described above can be obtained (claims 1 and 4 ).
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a suction chamber device and its periphery of a resin sheet molding casting apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of the suction chamber apparatus of FIG.
FIG. 3 is a side sectional view showing a conventional suction chamber.
4 is a perspective view of the suction chamber of FIG. 3. FIG.
[Explanation of symbols]
1: T die, 2: Cooling roll, 3: Resin sheet, 3a: Molten resin, 5: Suction blower, 9: Suction port, 10: Suction chamber device, 11: Suction chamber body, 11a: Upper plate, 11b, 11c : Side wall, 11d: back plate, 12: receiving plate, 13: perforated plate, 14: suction port, 15, 15a: seal packing, 16: seal packing, 17: guide plate, 18: hose, 19: suction port manifold

Claims (4)

In the manufacturing method of the resin sheet that is cooled and solidified on the cooling surface that moves the molten resin extruded from the die in a predetermined direction,
A suction chamber body having a suction space that is disposed upstream of the predetermined direction from the point of falling of the molten resin onto the cooling surface and to which the lower surface of the die is exposed;
A heat-resistant U-shaped seal packing interposed between the lower surface of the die and the edge of the U-shaped opening close to the lower surface of the die of the suction chamber body;
A backing plate that contacts the back side wall opposite to the die opening of the suction chamber body and faces the cooling surface over the entire width of the suction chamber body;
A plurality of suction ports communicating with the suction space;
A suction outlet manifold that pipe-connects the suction outlet and the suction blower;
By a suction chamber device constituted by a perforated plate provided in a passage of suction air in the suction space,
A method for producing a resin sheet, comprising sucking air between the cooling surface and the molten resin so that the molten resin is brought into close contact with the cooling surface to be cooled and solidified.   The method for producing a resin sheet according to claim 1, wherein the resin is a polyolefin.   The method for producing a resin sheet according to claim 2, wherein the polyolefin is linear low density polyethylene. In a resin sheet molding casting apparatus that molds a resin sheet by cooling and solidifying a molten resin extruded from a die on a cooling surface that moves in a predetermined direction,
A suction chamber body that is open toward the molten resin extruded from the die and removes the lower wall facing the cooling surface and leaving the upper wall contacting the lower surface of the die, leaving a side wall;
A heat-resistant U-shaped seal packing interposed between the lower surface of the die and the edge of the U-shaped opening close to the lower surface of the die of the suction chamber body;
A backing plate that contacts the back side wall opposite to the die opening of the suction chamber body and faces the cooling surface over the entire width of the suction chamber body;
A plurality of suction ports;
A suction manifold connected to the suction blower and piping;
A casting apparatus for molding a resin sheet, comprising a suction chamber device comprising a perforated plate provided in a suction air passage of the suction chamber body.

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