JP4918011B2 - Manufacturing method of wide shape retaining sheet - Google Patents

Description

  The present invention relates to a method for manufacturing a wide shape-retaining sheet by abutting and fusing side end portions of a plurality of narrow shape-retaining sheets.

Since the shape-retaining sheet is plastically deformed and retains the deformed shape after the deformation, the binding material (see, for example, Patent Document 1), the core material of the body fixing tool (for example, see Patent Document 2), and the shape retention. It is used for a type cap (for example, refer to Patent Document 3).
Japanese Patent No. 3582854 JP 2004-57509 A Japanese Patent Laid-Open No. 11-93012

The shape-holding sheet is, for example, “the thickness of the maximum thickness portion made of the polyethylene melt-solidified product by melting a general-purpose polyethylene having an intrinsic viscosity [η] of less than 3.5 dl / g and extruding it into a raw yarn or a raw belt shape. Is formed into a raw yarn or belt of 1 mm or more, and the return angle after 10 minutes from bending the stretched product 180 degrees at a temperature of 60 ° C. or higher and lower than the melting point of polyethylene is 20 degrees or less, and A method for producing a thread-like or belt-like plastically deformable polyethylene material, characterized by stretching until 90 minutes after the 90-degree folding, and the return angle after 15 minutes is 15 degrees or less "(see, for example, Patent Document 1). “A step of rolling a sheet mainly composed of high-density polyethylene having a weight average molecular weight of 500,000 or less and a step of stretching the rolled sheet, and the total stretching ratio is 10 times through the rolling step and the stretching step. Polyethylene binding tape manufacturing method characterized by uniaxially stretching the above. "(E.g., see Patent Document 4.) As proposed, it has been manufactured by drawing or rolling.
JP-A-11-222256

  That is, since the shape-retaining sheet is produced by stretching a polyolefin resin sheet at a high magnification, it is impossible to obtain a wide shape-retaining sheet. It is difficult to manufacture because it must be manufactured by fixing it with adhesive tape, stapler, etc., and the mechanical properties of the obtained product are not uniform and the performance is unstable and difficult to use .

  In view of the above problems, an object of the present invention is to provide a method capable of easily producing a wide shape-retaining sheet.

The method for producing a wide shape retaining sheet of the present invention comprises a stretched polyolefin resin sheet, bent at 180 degrees and 90 degrees, held for 1 minute and then released, and the folding return angle when 5 minutes passed after release. In the method for producing a wide shape-holding sheet in which both side ends of the shape-holding sheet having both θ of 20 degrees or less are joined and the butted parts are fused, the polyolefin-based resin is provided on at least one surface of the stretched polyolefin-based resin sheet. An adhesive sheet made of a polyolefin resin having a melting point lower than that of the resin is laminated.

  The shape-retaining sheet used in the present invention is made of a stretched polyolefin resin sheet, bent at 180 degrees and 90 degrees, held for 1 minute and then released, and the folding return angle θ when 5 minutes passed after release is Both are sheets of 20 degrees or less.

  The shape-holding sheet has shape-holding properties, but the shape-holding sheet is released after folding the shape-holding sheet at 180 degrees and 90 degrees and holding it for 1 minute, and when 5 minutes have passed since release. Both bending return angles θ are 20 degrees or less, preferably 180 degrees folding return angle θ is 20 degrees or less and 90 degrees folding return angle θ is less than 20 degrees, more preferably 180 degrees folding return angle θ. Is 20 degrees or less and the 90-degree folding return angle θ is 15 degrees or less. If one of the 180 ° and 90 ° folding return angles θ, particularly the 180 ° folding return angle θ exceeds 20 °, sufficient shape retention may not be obtained.

  As the polyolefin-based resin constituting the stretched polyolefin-based resin sheet, any olefin-based resin having a film forming ability can be used. For example, a high-density polyethylene resin, a medium-density polyethylene resin, a low-density polyethylene resin, a linear low-density Polyethylene resin, polypropylene resin, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene -Vinyl acetate copolymer, ethylene- (meth) acrylic ester copolymer, ethylene-vinyl chloride copolymer, ethylene-propylene-butene copolymer, etc., and high-density polyethylene resin is preferably used .

  When the weight average molecular weight of the polyolefin resin is less than 100,000, the polyolefin resin becomes brittle, the stretchability becomes poor, and a stretched polyolefin resin sheet having sufficient strength or creep resistance can be obtained. Conversely, if it exceeds 500,000, the melt viscosity becomes high, the hot melt molding processability is lowered, and it becomes difficult to obtain a uniform sheet, so 100,000 to 500,000 is preferable. In the present invention, the weight average molecular weight is a value measured by gel permeation chromatography (GPC).

The melt index (hereinafter referred to as MI) of the polyolefin resin is preferably 0.1 to 20 (g / 10 minutes), more preferably 0.2 to 10 (g / 10 minutes), which is excellent in film moldability. is there. MI is an index representing the melt viscosity of a thermoplastic resin specified in JIS K 7210. Furthermore, in the case of a high density polyethylene resin, 0.94 g / cm ³ or more is preferable because the mechanical strength does not improve even if the density is reduced even if the density is reduced.

  As the stretched polyolefin resin sheet, a stretched polyolefin resin sheet having a shape-retaining property in which a polyolefin resin sheet having a weight average molecular weight of 100,000 to 500,000 is stretched at a stretch ratio of 5 times or more is preferable.

  In this case, the polyolefin resin is preferably a high-density polyethylene resin having an intrinsic viscosity [η] of less than 3.5 dl / g, such as glass fiber, talc, mica, calcium carbonate, magnesium hydroxide, alumina, zinc oxide, magnesium oxide, It is preferable to add inorganic machine fillers such as aluminum hydroxide, silica alumina, titanium oxide, calcium oxide, calcium silicate, basic magnesium carbonate, carbon fiber, and carbon black.

  The thickness of the polyolefin resin sheet before stretching is not particularly limited, but if it is too thick, stretching becomes difficult. Conversely, if it is too thin, the thickness of the polyolefin resin sheet after stretching becomes too thin. Since shape retainability is lowered, 0.2 to 15 mm is desirable.

  The stretching ratio is 5 times or more, and the stretched stretched polyolefin resin sheet only needs to have shape retention, but 10 to 40 times is preferable. The stretching method may be any conventionally known method, such as a method of stretching while heating with a heater or hot air by a uniaxial stretching method such as a roll uniaxial stretching method or a zone uniaxial stretching method. .

  When stretching uniaxially to a high degree of 10 to 40 times, a multistage uniaxial stretching method in which uniaxial stretching is repeated a plurality of times is preferable. When performing multistage uniaxial stretching, the number of stretching is preferably 2 to 20 times, more preferably 3 to 15 times, still more preferably 4 to 10 times.

  When performing multi-stage stretching by a roll uniaxial stretching method, it is desirable to install a feeding pinch roll, a take-up pinch roll, and at least one, preferably a plurality of contact rolls that rotate at a constant speed between these rolls. By installing such a contact roll, uniform stretchability is improved and stable stretch molding can be performed.

  The contact roll performs uniaxial stretching by applying a frictional force to the polyolefin resin sheet without being pinched. Further, the contact roll may be connected to the feeding roll and / or the take-up roll by a connecting member made of a gear, a chain, a pulley, a belt, or a combination thereof.

  The uniaxial stretching temperature cannot be uniformly stretched when it is low, and the sheet melts and cuts when it is high. Therefore, the range of “melting point−60 ° C.” to the melting point of the polyolefin resin of the polyolefin resin sheet to be stretched is more preferable, It is “melting point−50 ° C.” to “melting point−5 ° C.” of the polyolefin resin.

  Further, as a different preferred stretched polyolefin resin sheet, a polyolefin resin sheet having a weight average molecular weight of 100,000 to 500,000 was rolled to a rolling ratio of 5 times or more, and then the total stretching ratio was uniaxially stretched to 10 to 40 times. A stretched polyolefin resin sheet may be mentioned.

  The thickness of the polyolefin-based resin sheet before rolling is not particularly limited, but if it is too thick, stretching becomes difficult, and in the rolling process, a large pressing force is required to crush the polyolefin-based resin sheet with a rolling roll. Take-up force is required, and uniform rolling in the width direction may be difficult due to bending of the rolling roll, etc., conversely, if too thin, the thickness of the polyolefin resin sheet after stretching or rolling becomes too thin, Since not only uniform rolling becomes difficult, but also the rolling rolls come into contact with each other to shorten the life of the rolling roll, 0.2 to 15 mm is desirable.

  The polyolefin resin sheet is first rolled to a rolling ratio of 5 times or more. However, the rolling temperature cannot be uniformly rolled when the temperature is lowered, and melted and cut when the temperature is high. The range of “melting point −40 ° C.” to the melting point of the olefin resin of the polyolefin resin sheet is more preferable, and more preferably “melting point −30 ° C.” to “melting point −5 ° C.” of the olefin resin. In the present invention, the melting point refers to the maximum point of the endothermic peak that accompanies melting of the crystal, which is recognized when thermal analysis is performed with a differential scanning calorimeter (DSC).

  If the applied pressure (linear pressure) applied to the polyolefin resin sheet by the rolling roll is too small, it may not be possible to obtain a predetermined rolling magnification, and conversely if it is too large, not only will the bending of the rolling roll occur, Sliding easily occurs between the rolling roll and the raw sheet, and uniform rolling may be difficult. Therefore, the applied pressure is preferably 100 MPa to 3000 MPa, and more preferably 300 MPa to 1000 MPa.

  When the rolling ratio is less than 5 times, the effect of suppressing necking at the time of uniaxial stretching performed later cannot be obtained, high-strength uniaxial stretching cannot be performed, or the uniaxial stretching step Therefore, it is 5 times or more, preferably 7 times or more. There is no particular upper limit to the rolling ratio, but the higher the rolling ratio, the more load is applied to the rolling equipment, so 10 times or less is preferable.

  The rolling magnification is defined as (cross-sectional area of polyolefin resin sheet) / (cross-sectional area of polyolefin resin sheet after rolling), but the width of the polyolefin resin sheet hardly changes before and after rolling. (Thickness of resin sheet) / (thickness of polyolefin resin sheet after rolling).

  The rolled polyolefin resin sheet is then uniaxially stretched at a total stretch ratio of 10 to 40 times. The uniaxial stretching method is not particularly limited, and the above-described uniaxial stretching method may be adopted. Moreover, since the total draw ratio is 10 to 40 times, the uniaxial draw ratio may be determined so that the total draw ratio is within this range in consideration of the rolling ratio. Is not improved, it is preferably 1.3 times or more, more preferably 1.5 times or more, and still more preferably 1.8 times or more. Moreover, although an upper limit is not specifically limited, 4 times or less are preferable, More preferably, it is 3.5 times or less. The total draw ratio is a value obtained by multiplying the rolling ratio and the uniaxial draw ratio.

  In order to improve the dimensional stability of the stretched polyolefin resin sheet, the stretched polyolefin resin sheet may be annealed at a temperature of the melting point of the polyolefin resin from “melting point−60 ° C.” to the melting temperature or lower.

  If the annealing temperature is lowered, the dimensional stability will not improve, warping will occur if used for a long time, and if it is raised, the polyolefin resin will dissolve and the orientation will disappear and the tensile modulus, tensile strength, etc. will decrease. It is preferable that the resin be annealed at a temperature ranging from “melting point −60 ° C.” to the melting point and below the rolling temperature.

  Annealing is a heat treatment in the production line. When annealing, the stretched polyolefin resin sheet is stretched if a large tension is applied, and it is not tensioned or shrinks in a very small state. The length of the stretched polyolefin resin sheet in the stretching direction is preferably kept substantially unchanged, and it is preferable that no pressure is applied to the stretched polyolefin resin sheet. That is, it is preferable that the annealed stretched polyolefin resin sheet is annealed so that the length of the stretched polyolefin resin sheet before annealing is 1.0 or less.

  Accordingly, when the stretched polyolefin resin sheet is continuously annealed while being moved in the heating chamber with a roll such as a pinch roll, the feed rate ratio of the polyolefin resin sheet on the inlet side and the outlet side is 1.0 or less. It is preferable to anneal with setting.

  The heating method at the time of annealing is not particularly limited, and examples thereof include a method of heating with hot air, a heater, a heating plate, hot water or the like. The time for annealing is not particularly limited, and varies depending on the thickness of the stretched polyolefin resin sheet and the annealing temperature, but is generally preferably 10 seconds or more, more preferably 30 seconds to 60 minutes, and still more preferably 1 to 20 Minutes.

  The annealed polyolefin resin sheet may be further aged in a temperature range from 40 ° C. to the melting point of the polyolefin resin. The dimensional stability of the polyolefin resin sheet annealed by aging becomes more excellent.

  Aging is not a continuous treatment in the production line, but it is a relatively long time (minutes, time units) for heat treatment of single-wafers, scrolls, etc., once processed, such as cut winding, of a stretched polyolefin resin sheet. It means to lay down carefully and heat-treat.

  The aging temperature is the same as that left at room temperature when the temperature is low, and when it is high, it is thermally deformed, so the temperature range is from 40 ° C. to the melting point of the polyolefin resin, and the aging time is not effective in a short time and is too long. Even if an effect does not increase, 12 hours-7 days are preferable.

In the shape maintaining sheet, an adhesive sheet made of a polyolefin resin having a melting point lower than that of the polyolefin resin is laminated on at least one surface of the stretched polyolefin resin sheet. In order to abut the side ends of the shape-holding sheet and fuse the abutting portions, in particular, to heat and press with an ultrasonic welder or a hot press, the adhesive sheet is attached to both sides of the stretched polyolefin resin sheet. Are preferably laminated.

  The polyolefin resin constituting the adhesive sheet may be any polyolefin resin having a melting point lower than that of the polyolefin resin constituting the stretched polyolefin resin sheet. For example, low density polyethylene resin, linear low density polyethylene Examples thereof include resins and ethylene-vinyl acetate copolymers.

  Although the thickness of the said shape maintenance sheet | seat is not specifically limited, Generally it is 20-2000 micrometers, Preferably it is 100-1000 micrometers. The thickness of the stretched polyolefin resin sheet is not particularly limited. However, since the shape retainability decreases when the stretched polyolefin resin sheet becomes thin, it is generally 10 to 1860 μm, and preferably 100 to 1000 μm.

  Also, the thickness of the adhesive sheet is not particularly limited, but when the thickness is too thin, the side ends are abutted with each other, and the abutting part is fused when heated and pressed by an ultrasonic welder or a heating press. Since it becomes difficult to do, generally it is 5-150 micrometers, Preferably it is 20-80 micrometers.

  In this invention, the side edge parts of the said shape maintenance sheet | seat are faced | matched, and a facet part is melt | fused. The method of fusing is not particularly limited. For example, by heating and melting the side end portions of the shape holding sheets on both sides with a welding rod or hot air, the side end portions are brought into contact with each other by an ultrasonic welder or a heating press. Examples include a method of fusing the shape-holding sheets on both sides of the butt portion by heating and pressing the butt portion (end portion) of the shape-holding sheet. In addition, when the side edge parts of the shape-holding sheets are abutted with each other, it is preferable that the extending directions of both shape-holding sheets are parallel.

  In addition, when the adhesive sheet is laminated, the polyolefin resin constituting the adhesive sheet has a lower melting point than the polyolefin resin constituting the shape maintaining sheet, so that it is higher than the melting point of the polyolefin resin constituting the shape retaining sheet. The polyolefin resin constituting the adhesive sheet is melted at a low temperature, and the polyolefin resin of the adhesive sheet on both sides of the butt portion can be fused by pressurizing with an ultrasonic welder or a hot press. It is possible to fuse the shape-retaining sheets that are joined together. At this time, the polyolefin-based resin constituting the shape-holding sheet is also melted, and the shape-holding sheets on both sides of the abutting portion may be fused together by applying pressure.

  As a method of fusing with an ultrasonic welder, any conventionally known method may be employed. For example, the side end portions of the shape holding sheet are butted together, and the shape holding sheets on both sides are sandwiched between 15 to 15 mm. There is a method of passing between a horn and a knurl that are vibrated at a frequency of 40 kHz while applying pressure between the horn and the knurl.

  The shape-holding sheet in which the side ends are abutted with each other is transferred while being pressed by the horn and the knurling so that the abutting part is substantially at the center, and the horn is vibrated at a frequency of 15 to 40 kHz. The polyolefin resin that forms the shape-retaining sheet is heated and melted instantaneously by frictional heat generated by ultrasonic vibration transmitted from the tube, and the molten polyolefin resin that is pressed by the horn and knurling is pushed to the abutment and fused together. To do.

  When the adhesive sheets are laminated, the polyolefin resin constituting the adhesive sheet is heated and melted, and the polyolefin resin melted by applying pressure with a horn and a knurling is pushed to the abutting portion, and both are fused. In this case, it goes without saying that the shape-retaining sheets on both sides of the butt portion may be fused together by heating and melting the polyolefin resin constituting the shape-retaining sheet.

  In order to pressurize, it is preferable to connect an air cylinder, a hydraulic cylinder, etc. to a horn, and to press a horn to a knurling through the butt | matching part of a shape maintenance sheet | seat. Also, by forming protrusions on the knurl surface at regular intervals, it is possible to fuse more efficiently, and by changing the arrangement and shape of the protrusions, the arrangement and shape pattern of the fusion sites can be changed. Can change.

  In addition, as a method of fusing by hot pressing, any conventionally known method may be adopted. For example, the shape holding sheets are joined to each other at the side ends, and the shape holding sheets on both sides are placed between the abutting portions. An example is a method of passing through a press while heating and pressing.

  As the hot pressing, any conventionally known hot pressing method may be employed, and examples thereof include a method of pressing with a massive hot press, a method of pressing while feeding a shape-holding sheet with a heating roll, and the like.

  Even when fusing by hot pressing, it is possible to fuse more efficiently by forming protrusions on the press surface at regular intervals, and by changing the arrangement and shape of the protrusions, The pattern of arrangement and shape can be changed.

  In addition, when the shape-holding sheet is melted when the side edges of the shape-holding sheet are butted and bonded by heating and pressurizing the butted portion with an ultrasonic welder or a heating press, the shape-retaining property may be deteriorated. Since the thickness of the fused portion of the holding sheet is reduced, it is preferable that the shape-holding sheet is fused without being melted so much.

  In the case of fusing with a hot press, the melting point of the polyolefin resin constituting the shape maintaining sheet is preferably 2 ° C. or more higher than the melting point of the polyolefin resin constituting the adhesive sheet, more preferably 5 ° C. or more. .

  Since the structure of the manufacturing method of the wide shape maintenance sheet | seat of this invention is as above-mentioned, since the side edge parts of the shape maintenance sheet | seat which consists of an extending | stretching polyolefin-type resin sheet are butt | matched and a butt | matching part is fuse | melted, both The shape-holding sheets can be easily and firmly fused to produce a wide shape-holding sheet.

In addition, since an adhesive sheet made of a polyolefin resin having a melting point lower than that of the polyolefin resin constituting the shape holding sheet is laminated on at least one surface of the shape holding sheet, the side edges of the shape holding sheet are butted together. When the butt portion is heated and pressurized with an ultrasonic welder or a heating press and fused, the adhesive sheet between the two adhesive sheets is easily and firmly fused without degrading the shape retaining property of the shape retaining sheet, thereby maintaining a wide shape. Sheets can be manufactured.

  Further, the obtained wide shape holding sheet is bent at 180 degrees and 90 degrees, held for 1 minute and then released, and the folding return angle θ after 5 minutes has been released is less than 20 degrees. Only the abutting part where the side edges of the holding sheet are abutted is heated and pressurized by an ultrasonic welder or a heat press, so that the shape retainability does not deteriorate during fusion. Is excellent.

Next, examples of the present invention will be described, but the present invention is not limited to the following examples.
Example 1
A high-density polyethylene resin (manufactured by Nippon Polyethylene Co., Ltd.) having a weight average molecular weight (Mw) of 330,000 and a melting point of 135 ° C. is supplied to the same-direction biaxial kneading extruder (manufactured by Plastic Engineering Laboratory) and melt kneaded at a resin temperature of 200 ° C. After that, the melt-kneaded product was formed into a sheet having a width of 340 mm and a thickness of 3.5 mm using a calender molding machine controlled at a roll temperature of 110 ° C. to obtain a polyethylene resin sheet.

  The obtained polyethylene resin sheet was rolled at a rolling magnification of 7.5 times using a rolling molding machine (manufactured by Sekisui Koki Co., Ltd.) heated to 125 ° C. to obtain a rolled polyethylene resin sheet having a thickness of 0.48 mm. The obtained rolled polyethylene resin sheet is stretched 1.5 times with a hot-air heating type multi-stage stretching apparatus (manufactured by Kyowa Engineering) heated to 110 ° C., the total stretching ratio is 11.5 times, the width is 280 mm, the thickness is A stretched polyethylene resin sheet having a thickness of 0.4 mm was obtained.

  The obtained stretched polyethylene resin sheet was supplied with a pinch roll to a hot air heating tank with a line length of 19.25 m set at 125 ° C. at an inlet speed of 2.75 m / min, and an outlet speed of 2.75 m / min. Set to, and then subjected to primary annealing for 7 minutes, followed by secondary annealing in the same manner to obtain an annealed stretched polyethylene resin sheet, which is then fed to a constant temperature bath at 60 ° C. and aged for 24 hours, An aged stretched polyethylene resin sheet (shape maintaining sheet) was obtained.

  The obtained shape-holding sheet was cut into a width of 1 cm and a length of 15 cm, bent at 180 degrees and 90 degrees, held for 1 minute and then released, and the bending return angle θ after 5 minutes from the release was measured. , 5 degrees and 8 degrees, respectively.

A shape having a thickness of 0.46 mm is obtained by extrusion-molding a low-density polyethylene resin (manufactured by Sekisui Film Co., Ltd.) having a melting point of 121 ° C. to a thickness of 0.03 mm on both sides of the obtained stretched polyethylene resin sheet and laminating an adhesive sheet. A holding sheet was obtained.

  The obtained shape-holding sheet was cut into a width of 1 cm and a length of 15 cm, bent at 180 degrees and 90 degrees, held for 1 minute and then released, and the bending return angle θ after 5 minutes from the release was measured. , 5 degrees and 8 degrees, respectively.

  The obtained shape-retaining sheet was cut into a stretching direction of 625 mm and a width direction (perpendicular to the stretching direction) of 250 mm, and the two end-cut shape-retaining sheets were butted together so that the stretching directions were the same, The butt is supplied so that it is approximately the center of the horn and knurl of an ultrasonic welder (trade name “SONOPET Σ-1200” manufactured by Seidensha Electronics Co., Ltd.), and the horn has a clearance of 0.2 mm and a pressure of 0.8 MPa. And a knurl at a speed of 2 m / min, and by vibrating at a frequency of 15 to 40 kHz from a horn and fusing with ultrasonic welder, a wide shape holding sheet having a width of 500 mm and a thickness of 0.46 mm is obtained. Obtained.

  Protrusions were formed on the knurled surface at regular intervals, and substantially the same pressing pattern was formed in parallel on both sides of the abutting part of the obtained shape-retaining sheet. The size of the press patterns was about 0.8 mm in length and about 0.5 mm in width on both sides of the abutting portion along the supply direction, and the distance between the press patterns was about 1.5 mm.

  Further, the obtained wide shape-holding sheet is cut into a width of 1 cm and a length of 15 cm so that the abutting portion is substantially in the center, bent at 180 degrees and 90 degrees, held for 1 minute, released, and then released 5 When the bending return angle θ was measured when minutes passed, they were 5 degrees and 8 degrees, respectively.

Claims (3)

The side of the shape-retaining sheet that is made of a stretched polyolefin resin sheet, bent at 180 degrees and 90 degrees and held for 1 minute, then released, and the folding return angle θ is less than 20 degrees when 5 minutes have passed after release. In the method for producing a wide shape maintaining sheet in which the ends are butted together and the butted parts are fused , at least one surface of the stretched polyolefin resin sheet has an adhesive property made of a polyolefin resin having a melting point lower than that of the polyolefin resin. A method for producing a wide shape-retaining sheet, wherein the sheets are laminated . The method for producing a wide shape-retaining sheet according to claim 1, wherein the stretched polyolefin resin sheet is obtained by stretching a polyolefin resin sheet having a weight average molecular weight of 100,000 to 500,000 to a stretch ratio of 5 times or more. . The stretched polyolefin resin sheet is characterized in that a polyolefin resin sheet having a weight average molecular weight of 100,000 to 500,000 is rolled to a rolling ratio of 5 times or more and then uniaxially stretched to a total stretching ratio of 10 to 40 times. The manufacturing method of the wide shape maintenance sheet | seat of Claim 1 .