JP5149029B2 - Manufacturing method of composite sheet - Google Patents

Description

  The present invention relates to a method for producing a composite sheet obtained by bonding a resin material extruded from a die and a base sheet.

  As a technique related to a composite sheet obtained by bonding a resin material extruded from a die and a base material sheet, a technique described in Patent Document 1 is known. The composite sheet described in the same document forms a large number of arch portions 13 on the sheet 12 by corrugated members 20 and 21 having a gear shape, as shown in FIGS. The elastic strand 16 is fused to the top (bottom) of the arch portion 13. The elastic strands 16 are extruded from the die 22 in a molten state, and are fused to the sheet 12 by the sandwiching pressure by the corrugated members 20 and 21 in an unstretched state. The elastic strand 16 is bonded to the sheet 12 by point contact, and it is not easy to increase the bonding strength due to this.

  Regarding the sheet clamping pressure, apart from the technology related to the production of the composite sheet, Patent Document 2 discloses that the resin sheet extruded from the die is clamped between the mold roller and the nip roller, and the uneven shape of the mold roller is applied to the resin sheet. A method for imparting is described. In this method, a plurality of nip rollers are arranged on the peripheral surface of the mold roller and the clamping pressure is applied a plurality of times, thereby giving a desired uneven shape to the thick resin sheet. However, the document does not mention that the resin material extruded from the die is bonded to the base sheet.

Japanese National Patent Publication No. 10-501195 JP 2006-56214 A

An object of the present invention is to provide a method by which a resin sheet extruded from a die is bonded to a base sheet, and a composite sheet having high delamination strength and excellent texture and touch can be easily produced.
Another object of the present invention is to provide a method capable of easily producing a stretchable composite sheet having a high return strength after being stretched when the resin material is an elastic material.

The present invention is a method for producing a composite sheet by passing a resin material extruded from a die between nip rolls together with a substrate sheet being conveyed, and bonding the substrate sheet and the resin material together.
The present invention provides a method for producing a composite sheet in which nip rolls are installed in multiple stages and the nip pressure at the second stage is higher than the nip pressure at the first stage.

  According to the present invention, a composite sheet having improved peel strength between the base sheet and the resin material extruded from the die can be produced at high speed without impairing the original texture of the base sheet.

  The present invention will be described below based on preferred embodiments with reference to the drawings. First, an example of a composite sheet manufactured according to the method of the present invention will be described with reference to FIG. The composite sheet shown in FIG. 1 includes a total of two sheets, a first base sheet 11 and a second base sheet 12, and a large number of filaments 13 sandwiched between the two sheets. Each filament 13 is joined to the first and second substrate sheets 11 and 12. The first nonwoven fabric 11 and the second nonwoven fabric 12 may be of the same type or different types. The same type of sheet here means sheets having the same manufacturing process, types of sheet constituent materials, sheet thickness, basis weight, and the like. When at least one of these is different, the sheets are different.

  Each filament 13 is substantially continuous over the entire length of the composite sheet 10. The filaments 13 are arranged so as to extend in one direction without crossing each other. However, the filaments 13 are allowed to cross unintentionally due to inevitable fluctuations in the manufacturing conditions of the composite sheet 10. The filament 13 is bonded to the base material sheets 11 and 12 in a substantially non-stretched state.

  The manufacturing method of the composite sheet 10 having the above structure will be described with reference to FIG. In this manufacturing method, a large number of molten filaments 13 spun from a spinning nozzle 16 which is an example of a die are taken up at a predetermined speed, and before the filaments 13 are solidified, the filaments 13 do not cross each other in one direction. The filaments 13 are fused to the base material sheets 11 and 12 so as to be arranged in the same manner.

  The spinning nozzle 16 is provided in the spinning head 17. The spinning head 17 is connected to an extruder. Resin can also be supplied to the spinning head 17 via a gear pump. The resin melt-kneaded by the extruder is supplied to the spinning head 17. The spinning head 17 has a large number of spinning nozzles 16 arranged in a straight line. The spinning nozzle 16 is disposed along the width direction of the first and second substrate sheets 11 and 12. The interval between adjacent spinning nozzles 16 corresponds to the interval between filaments 13 in the target composite sheet 10. The spinning nozzle 16 is generally circular and its diameter affects the diameter of the filament 13. From this viewpoint, the diameter of the spinning nozzle 16 is preferably 0.1 to 2 mm, particularly preferably 0.2 to 0.6 mm. For the purpose of increasing the bonding strength with the base sheet 11, 12, the purpose of increasing the spinning property of the filament 13, and the purpose of improving various properties (for example, stretchability) of the composite sheet 10, the filament 13 is in a composite form (side-by-side, (Core sheath, sea-island structure). Specifically, for example, when it is desired to impart stretchability to the composite sheet 10, it is preferable to combine a PP-based elastomer resin and a styrene-based elastomer resin.

  The melted filaments 13 spun together with the first base sheet 11 and the second base sheet 12 fed from the original fabric at the same speed, and are sandwiched between the sheets 11 and 12. And picked up at a predetermined speed. The take-up speed of the elastic filament 13 coincides with the feeding speed of both the nonwoven fabrics 11 and 12. The take-up speed of the filament 13 affects the diameter of the filament 13 and the draw ratio. The tension generated in the filament 13 by stretching prevents the filament 13 from being disturbed due to wind or static electricity when the filament 13 is bonded to the base sheet 11 or 12. Thereby, the filaments 13 can be arranged in one direction without crossing each other. From these viewpoints, the take-up speed of the filament 13 is adjusted so that the draw ratio is 1.1 to 400 times, particularly 4 to 100 times, and further 10 to 80 times the resin discharge speed in the spinning nozzle hole. It is preferred that

  The filament 13 joins the first and second base sheets 11 and 12 before solidification, that is, in a state where the filament 13 can be fused. As a result, the filament 13 is fused to the base sheets 11 and 12 while being held between the first and second base sheets 11 and 12. That is, the filament 13 is drawn and stretched while the filament before solidification is fused to the substrate sheets 11 and 12 to be conveyed. When the filament 13 is fused, heat is not applied to the first and second base sheets 11 and 12 from the outside. That is, the filament 13 and the base material sheets 11 and 12 are fused only by the melting heat caused by the filament 13 that can be fused. As a result, only the site | part which exists around the filament 13 among both the sheets 11 and 12 fuse | melts with this filament 13, and the site | part distant from it does not fuse | melt. As a result, the heat applied to both sheets 11 and 12 is kept to a minimum, and the good texture inherent to the sheets themselves is maintained. Thereby, the texture of the composite sheet 10 obtained becomes favorable.

  Until the spun filament 13 joins the first and second base sheets 11 and 12, the filament 13 is stretched and molecules are oriented in the stretching direction. Also, the diameter is reduced. By the molecular orientation, a filament 13 having a small strength going / return ratio (hysteresis) at 50% elongation can be obtained. From the viewpoint of sufficiently stretching the filament 13 and preventing the filament 13 from being broken, it is possible to adjust the temperature of the filament 13 by blowing wind (hot air or cold air) at a predetermined temperature onto the spun filament 13. Good.

  The stretching of the filament 13 is not limited to stretching in the molten state of the raw material resin (melt stretching), but may be stretching in a softened state (softening stretching) in the cooling process. The molten state is a state in which the resin flows when an external force is applied. The melting temperature of the resin is measured as a peak temperature of Tan δ by viscoelasticity measurement (for example, measured by adding vibration strain in the rotational direction to a resin sandwiched between circular parallel plates). In order to prevent yarn breakage when the resin is stretched, it is preferable to secure a long stretch section. Similarly, from the viewpoint of preventing thread breakage, the melting temperature of the elastic resin is preferably 130 to 300 ° C. Further, the resin preferably has a melting temperature of 220 ° C. or less from the viewpoint of heat resistance. The molding temperature of the filament 13 (die temperature) is preferably + 50 ° C. or higher of the melting temperature of the raw resin from the viewpoint of improving the flowability of the resin and improving moldability, and the melting temperature of the raw resin + 110 ° C. from the viewpoint of heat resistance. The following is preferred. The softening temperature is measured as the Tg temperature in the viscoelastic property of the measurement sample of the elastic resin in sheet form. The range from the softening temperature to the melting temperature is called a softened state. Moreover, the state of temperature lower than softening temperature is called solidified state. The softening temperature is preferably 60 ° C. or higher, and more preferably 80 to 180 ° C. from the viewpoint of resin crystal growth during storage of the composite sheet 10.

  The temperature of the filament 13 when the filament 13 and the base sheet 11, 12 are joined is preferably 100 ° C. or higher in order to ensure fusion with the base sheet 11, 12. More preferably, it is 120 degreeC or more, More preferably, it is 140 degreeC or more. From the viewpoint of maintaining the shape of the filament 13, the temperature of the filament is preferably 180 ° C. or lower. More preferably, it is 160 degrees C or less. As a result, the optimum filament temperature when joining the filament 13 and the base sheet 11, 12 is in the range of 120 to 160 ° C, more preferably 140 to 160 ° C. The bonding temperature is determined by observing the bonding state using a film made of modified polyethylene or modified polypropylene having a melting point different from the melting point of the elastic resin constituting the filament as a laminate base material to be bonded to the filament 13. It can be measured. At this time, if the filament and the laminate base material are fused, the joining temperature is equal to or higher than the melting point of the laminate base material.

  At the time of joining the filament 13 and the base material sheets 11 and 12, the filament 13 is in a substantially non-stretched state (a state in which the filament 13 does not shrink when an external force is removed). Since the filament 13 is bonded to the base material sheets 11 and 12 in a substantially non-elongated state, when the filament 13 has elasticity, the composite sheet 10 ′ having elasticity that has been subjected to an elastic expression process described later, There is an advantage that relaxation (creep) does not occur due to elongation, and stretchability is not easily lowered.

  In the joined state of the filament 13 and the base sheet 11, 12, it is preferable that at least a part of the sheet 11, 12 is fused to the filament 13, and both the filament 13 and at least a part of the sheet 11, 12 are both. It is more preferable to fuse. This is because sufficient bonding strength can be obtained.

  When the filament 13 is merged with the first and second substrate sheets 11 and 12, the filaments 13 are arranged in one direction without crossing each other. Then, the filament 13 is merged with the first and second substrate sheets 11 and 12 to form a complex 30 in which the filament 13 is sandwiched between the substrate sheets 11 and 12. Clamping is performed with a nip roll. The nip roll used in this manufacturing method is composed of one main roll 18 and three sub-rolls 19a, 19b, 19c. The main roll 18 and the three sub-rolls 19a, 19b, 19c have smooth peripheral surfaces, and are made of, for example, metal or rubber. The three sub rolls 19 a, 19 b, 19 c are arranged so that their axes are parallel to the axis of the main roll 18. Further, the three sub-rolls 19 a, 19 b, 19 c are arranged so that their peripheral surfaces face the peripheral surface of the main roll 18. Further, the three sub-rolls 19a, 19b, 19c have the first sub-roll 19a located on the upstream side in the rotation direction of the main roll 18, and the second sub-roll 19b and the third sub-19c roll located on the downstream side. Are arranged as follows. With such a configuration, in the manufacturing apparatus shown in FIG. 2, the main roll 18 and the first sub roll 19a constitute the first stage nip roll, and the main roll 18 and the second sub roll 19b constitute the second stage nip roll, Further, a third nip roll is constituted by the third sub roll 19c.

  As described above, the nip rolls are installed in multiple stages in the apparatus used in the present manufacturing method. Then, the composite 30 is sequentially passed through each stage of the nip rolls installed in multiple stages. This manufacturing method has one of the characteristics in the processing of the composite 30 by multi-stage nip rolls. Specifically, a method is adopted in which the nip pressure at the second stage is higher than the nip pressure at the first stage. Accordingly, the bonding between the base sheets 11 and 12 and the filament 13 can be made strong without impairing the good texture that the base sheets 11 and 12 originally have. The reason for this is as follows.

  When the resin material extruded from the die and the base material sheet are bonded together by a conventional melt laminating method, a technique of increasing the temperature of the resin material is used to increase the bonding strength between the two. By increasing the temperature of the resin material, the viscosity of the resin material decreases, and the resin material easily bites into the base sheet. Moreover, when the raw material which comprises a base material sheet is a thermoplastic material, since the thermoplastic material which comprises a base material sheet fuse | melts and a resin material and a base material sheet are melt-bonded, the adhesive strength increases. In these cases, the bonding strength between the two becomes high, but because the temperature of the resin material is high, as described above, the resin material bites into the base sheet or the whole base sheet (resin bonding of the base sheet). There is an inconvenience that not only the surface but also the outer surface opposite to the joint surface is thermally contracted and melted, and the texture and the like inherent to the base sheet is impaired. That is, it is difficult for the conventional melt laminating method to achieve both joint strength and texture.

  More specifically, it will be described below that it is difficult to eliminate this inconvenience by the conventional melt laminating method. As a method of adjusting the bonding strength by the conventional melt laminating method, (1) the method of widening the air gap (distance from the die extrusion port (spinning nozzle 16 in FIG. 2) to the junction of the resin material and the base sheet) And (2) a method of providing a nip clearance (a method of widening the gap between the main roll 18 and the sub-roll 19a as shown in FIG. 2 in this patent). However, in the method of widening the air gap of (1), the temperature of the resin material is substantially lowered before being bonded to the base sheet, and it is difficult to increase the bonding strength. It is not easy to achieve both. In addition, the method of widening the air gap is such that when the resin material is a neck-in or the molten resin material is a filament, the filament meanders or the filaments are bundled together, or the filament is disturbed. Problems also arise in the extrusion process before the material joins the base sheet. In addition, in the method of (2) providing the nip clearance, the resin material and the base material sheet do not adhere so much at the time of the nip, so the resin material hardly bites in, and the base material sheet is hardly joined to the resin material. Since the base sheet and the resin material are hardly fused without being melted, it is difficult to increase the joining strength, and it is not easy to achieve both the joining strength and the texture.

  In contrast, the method in which the nip rolls of the present invention are installed in multiple stages and the nip pressure in the second stage is higher than the nip pressure in the first stage produces a molten laminated composite sheet that balances bonding strength and texture at high speed. This has the advantageous effect of being able to do so. The reason why both joint strength and texture can be achieved is that the resin material in the molten state is not brought into close contact with the base material sheet in the first stage nip, and the resin material is prevented from excessively biting into the base material sheet. , By transmitting the heat of fusion of the resin material not only to the entire base sheet, but only to the base sheet in the vicinity of the joint surface between the resin material and the base sheet, thereby partially melting the constituent materials of the base sheet Thus, the resin material and the base material sheet are partially joined (in this stage, the joining strength is insufficient because the joining is a partial fusion between the resin material and the base material sheet in the vicinity of the resin material. Thus, the texture is maintained, so that the texture is maintained), and then in the second and subsequent nips, part or all is softened (if part is softened, other Part melted or solidified The resin material and the base sheet are sufficiently adhered at a high nip pressure, and the base sheet is digged into the softened resin material. In the first nip, the resin material and the base sheet are partially fused. This is because the bonding strength can be increased and increased by anchor adhesion by partial biting of the base material sheet into the resin material. In other words, fusion and anchor adhesion while preventing the resin material from biting into the base material sheet and damaging the texture, and the base material sheet from being thermally contracted and melted as a whole, damaging the texture. By exhibiting these two joining forms, the effect of achieving both joining strength and texture is produced.

  Furthermore, the present invention is particularly effective when melt lamination is performed using a raw material that has a high melt viscosity and a high die temperature and needs to be molded as a resin material.

  In the present invention, the nip pressure is a pressure acting on the composite 30 when the composite 30 is sandwiched between the main roll 18 and each sub roll. The nip pressure is defined as the nip pressure (in the present invention, the force for pressing the sub rolls 19a, 19b, and 19c against the main roll 18 regardless of the composite and clearance), the nip roll diameter, and the roll surface hardness (for example, rubber (Hardness), surface shape of the roll (pattern roll: dots, stripes, lattices, etc.), intervals between the main roll 18 and the sub rolls 19a, 19b, 19c (clearance between rolls), etc. . Particularly, the nip pressure is adjusted by the clamping pressure and the clearance between the rolls, and the nip pressure increases as the clamping pressure increases and the clearance between the rolls decreases. Among these, the clamping pressure depends on the material of the base material sheets 11 and 12 and the filament 13, but it is preferably 1 to 150 N / cm, particularly 2 to 120 N / cm at the first stage in terms of linear pressure. The step is preferably 5 to 200 N / cm, particularly preferably 5 to 90 N / cm.

The nip pressure can also be obtained by the following method. When a clearance is provided, it is obtained by the following method. First, in a state where there is no composite 30, a force A that attempts to press the sub roll against the main roll is measured. Next, in a state where the composite 30 is present, the force B that attempts to press the sub roll against the main roll is measured. When the nip force acting on the composite 30 is C, the nip force C can be obtained from the following equation (a).
C = A−B (a)
Here, A and B are measured by, for example, a load cell installed in a clearance setting device installed to provide clearance between the main roll and the sub roll. From the nip force C, the nip pressure is obtained as a linear pressure from the following equation, where the substrate width is W.
Nip pressure = C / W (b)
When no clearance is provided (solid nip), the following formula (c) is obtained from the force (pressing force) for pressing the sub roll against the main roll by the machine setting and the width W of the composite 30.
Nip pressure (linear pressure) = pressing force / W (c)
If the pressing force is unknown in the machine settings, it is measured by the load cell.
In this case, the nip pressure is preferably 1 to 90 N / cm, particularly 2 to 60 N / cm at the first stage, and preferably 5 to 200 N / cm, particularly 5 to 90 N / cm at the second stage.

  From the viewpoint of making the above-described advantageous effects more remarkable, it is preferable to set the clearance of the first stage nip roll to be equal to or greater than the sum of the thickness of the extruded resin material and the thickness of the base sheet. By performing such an operation, in the first-stage nip roll, since the clearance is provided, damage to the filament 13 is reduced, and inconveniences such as breakage of the filament 13 are less likely to occur. Furthermore, the texture of the base material sheets 11 and 12 at the joint between the two is difficult to be damaged. In addition, the thickness of a base material sheet can be measured with a dial gauge etc. by A method, when a base material sheet is a film according to JISK7310. When the substrate sheet is other than a film, the thickness can be determined by dividing the basis weight of the substrate sheet by its specific gravity by the B method. The thickness of the resin material can be obtained by observing the cross section of the composite sheet with a microscope or SEM.

  Another condition for the nip roll pressure is the temperature of the nip roll. As a result of the study by the present inventors, rather than performing the clamping pressure while the nip roll is heated, it is better not to heat (i.e., leave it to the result) or to perform the clamping pressure while cooling. It was found that the sheet 10 was obtained. When the temperature of the nip roll is adjusted as the molding speed or temperature is changed, a coolant or a heat medium is used so that the surface set temperature of the main roll 18 and the sub rolls 19a, 19b, 19c is 10 to 80 ° C. It is preferable to adjust the temperature.

  Thus, the composite sheet 10 in which the filament 13 and the base material sheets 11 and 12 are bonded together is obtained. The composite sheet 10 is peeled from the peripheral surface of the main roll 18 by being wound around the peeling roll 31.

  The resin material used in this production method is not particularly limited as long as it is a thermoplastic resin that can be melt-laminated. For example, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as polyamide 6 and polyamide 66, acrylic resins such as polymethacrylate and polymethacrylate, vinyl Examples thereof include resins and polyacrylonitrile resins.

  When it is desired to impart stretchability to the composite sheet 10, for example, a thermoplastic elastomer can be used as the resin material. Examples of the thermoplastic elastomer include SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene). And olefin elastomers (ethylene-based α-olefin elastomers, propylene-based elastomers copolymerized with ethylene / butene / octene), polyester-based elastomers, and polyurethane-based elastomers.

  The filament 13 may be a single component type, or may be a core-sheath type or a side-by-side type multi-component type. Regardless of whether it is a single-component system or a multi-component system, the thickness of the filament 13 in the manufactured composite sheet 10 is 10 to 200 μm, particularly 20 to 130 μm in terms of diameter. It is preferable from the viewpoint of improving the texture of the sheet 10 and productivity. The pitch between the filaments 13 is preferably 0.1 to 5 mm, particularly preferably 0.4 to 2 mm.

As the base sheets 11 and 12, various sheet materials such as a film, a nonwoven fabric, paper, and a woven fabric can be used without particular limitation. Various conventionally known thermoplastic resins can be used as the constituent material of the film and the nonwoven fabric. Specific examples of the thermoplastic resin include those similar to those exemplified above as the thermoplastic resin constituting the filament 13. When the base sheets 11 and 12 are films, the basis weight is preferably 5 to 50 g / m ² , particularly preferably 10 to 40 g / m ² . The film may be provided with slits or openings as required. When the base sheets 11 and 12 are non-woven fabrics, an appropriate one is selected as the non-woven fabric according to the specific use of the composite sheet 10. Examples thereof include air-through nonwoven fabric, spunbond nonwoven fabric, spunlace nonwoven fabric, airlaid nonwoven fabric, resin bond nonwoven fabric, and needle punched nonwoven fabric. In this case, the thickness of the raw nonwoven fabric is preferably 0.05 to 5 mm, particularly preferably 0.1 to 1 mm, and particularly preferably 0.15 to 0.5 mm.

  When the composite sheet 10 is an expandable sheet, a preferable combination of the constituent materials of the base sheets 11 and 12 and the filament 13 is that the base sheets 11 and 12 are made of the same or different stretchable nonwoven fabric, and the filament 13 is It is preferable to make it from an elastic resin. In particular, the nonwoven fabric is preferably made of fibers having a maximum elongation of 80 to 800%, particularly 120 to 650%, from the viewpoint of obtaining a composite sheet 10 having a maximum maximum strength. The elongation of the raw fiber is measured in accordance with JIS L-1015 under the conditions of measurement environment temperature and humidity 20 ± 2 ° C., 65 ± 5% RH, tensile tester gripping distance 20 mm, and tensile speed 20 mm / min. In addition, when collecting fibers from an already produced non-woven fabric and measuring the elongation, etc., when the grip interval cannot be 20 mm, that is, when the length of the fiber to be measured is less than 20 mm, the grip interval is 10 mm or Set to 5 mm and measure.

  When producing a stretchable composite sheet using the above-described materials, the composite sheet produced using the apparatus shown in FIG. Specifically, as shown in FIG. 3, the composite sheet 10 manufactured using the apparatus shown in FIG. 2 is elastically treated along the direction in which the filament 13 extends, and the base sheets 11 and 12 are stretchable. The composite sheet 10 ′ having elasticity is obtained. In this manufacturing method, this operation is performed using an elastic expression device 22 including a pair of tooth space rolls 20 and 21 in which teeth and roots are alternately formed in the circumferential direction. That is, it is performed by performing an elastic expression process along the direction in which the elastic filament 13 extends.

  The elastic expression device 22 has a known lifting mechanism (not shown) that vertically displaces the pivot portion of one or both of the tooth gap rolls 20 and 21 so that the interval between the tooth gap rolls 20 and 21 can be adjusted. It has become. In this manufacturing method, each tooth gap roll 20 and 21 is inserted freely between the teeth of one tooth gap roll 21 and the tooth of the other tooth gap roll 21 is one tooth. It combines so that it may be loosely inserted between the teeth of the groove roll 20, and the composite sheet 10 is inserted between the both tooth groove rolls 20 and 21 of the state, and this is elastically processed.

  In the elastic expression device 22, both of the pair of tooth groove rolls 20 and 21 may be driven by a driving source (co-rotating roll), and only one tooth groove roll 20 or 21 is driven by the driving source. However, in this manufacturing method, only the lower tooth gap roll 21 is driven by the driving source, and the upper tooth groove roll 20 is not connected to the driving source. Instead, it follows (rotates) with the rotation of the tooth gap roll 21. As the tooth profile of the tooth gap rolls 20 and 21, a general involute tooth profile and a cycloid tooth profile are used, and those having a narrowed tooth width are particularly preferable.

  FIG. 4 schematically shows a state in which the composite sheet 10 is subjected to an elastic development process. When the composite sheet 10 passes between the tooth gap rolls 20 and 21, the composite sheet 10 is in a region that contacts the teeth 23 and 24 of the tooth gap rolls 20 and 21 (between P 3 and P 2 and between P 1 and P 4). Is hardly stretched. On the other hand, in the region (between P2 and P1) pressed toward the tooth surface of the tooth 23 of the tooth space roll 20 that is the driven roll by the tooth surface of the tooth 24 of the tooth space roller 21 that is the driving roll. The two teeth 20 and 21 are greatly stretched. Further, in the region (between P4 and P3) that is separated from the tooth 23 of the tooth space roll 20 by the tip of the tooth 24 of the tooth space roll 21, it is not as large as the region (between P2 and P1), but is greatly stretched. The

  Further, the composite sheet 10 is hardly stretched as described above in the regions (between P3 and P2 and between P1 and P4) in contact with the tips of the teeth 23 and 24 of the tooth gap rolls 20 and 21, but the teeth 23 and 24 are as described above. Is pushed in the radial direction, that is, in the thickness direction of the composite sheet 10, so that it becomes thinner in the thickness direction. However, because the region (between P3 and P2) and the region (between P1 and P4) are in the opposite direction, the thinning direction is the opposite direction.

  The stretching process can efficiently stretch both the base material sheets 11 and 12 in the composite sheet 10 and impart extensibility while preventing the filament 13 and the base material sheets 11 and 12 from being peeled off. . The composite sheet 10 ′ having the stretchability obtained by passing the composite sheet 10 through the tooth gap rolls 20 and 21 is released from the stretched state immediately after passing through the tooth gap rolls 20 and 21, and the filament 13 itself. By the restoring force in the shrinking direction, the length before stretching is almost recovered quickly. The composite sheet 10 ′ having stretchability thus obtained can be extended along the direction in which the filament 13 extends, and when the extended state is released, the filament 13 returns to the length before extension. As a result, the composite sheet 10 ′ exhibiting a restoring force and having elasticity is almost restored to its original state.

The above-described composite sheet 10 ′ having stretchability is suitably used as an exterior sheet of a pants-type disposable diaper, for example. In addition to this use, it can be used for various uses such as surgical clothes and cleaning sheets by taking advantage of its good texture, fuzz prevention, stretchability, breathability and the like. In particular, it is preferably used as a constituent material of absorbent articles such as sanitary napkins and disposable diapers. As the constituent material, for example, a surface sheet that is a liquid-permeable sheet (including sublayers) located on the skin side of the absorbent body, a sheet that constitutes the outer surface of the disposable diaper, a waistline part and a waist part, Examples thereof include a sheet for imparting elastic stretchability to the leg periphery and the like. Moreover, it can be used as a sheet or the like for forming a stretchable wing of a napkin. Moreover, even if it is another site | part, it can be used for the site | part etc. which want to provide a stretching property. The basis weight and thickness of the composite sheet 10 ′ having elasticity can be appropriately adjusted according to the specific application. For example, when used as a constituent material of an absorbent article, it is desirable that the basis weight is about 20 to 60 g / m ² and the thickness is about 0.5 to 1.5 mm.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, only the points different from the above-described embodiment will be described, and the description related to the above-described embodiment will be applied as appropriate to the points that are not particularly described. In FIG. 5, the same members as those in FIGS. 1 to 4 are denoted by the same reference numerals.

  The apparatus used for the manufacturing method of this embodiment includes one main roll 18 and three sub-rolls 19a, 19b, and 19c. The main roll 18 and the first sub roll 19a constitute a first stage nip roll, the main roll 18 and the second sub roll 19b constitute a second stage nip roll, and the main roll 18 and the third sub roll 19c constitute a third stage. An eye nip roll is constructed. Further, the apparatus shown in FIG. 5 includes a belt-like member 32 that sequentially passes between the nip rolls of each stage. The belt-like member 32 is an endless belt. The belt-like member 32 circulates in the same direction as the conveyance direction of the base material sheets 11 and 12.

  In the method for producing a composite sheet using this apparatus, the belt-like member 32 conveys the composite 20 in which the filaments 13 made of a resin material are sandwiched between the base material sheets 11 and 12, while The operation of passing through the nip rolls in stages is performed. According to this operation, clamping is also performed between the first sub-roll 19a and the second sub-roll 10b and between the second sub-roll 19b and the third sub-roll 19c. In other words, the area for pressing the composite 20 against the main roll 18 increases. As a result, even if the nip pressure at each stage is lowered, the bonding strength between the base sheet 11, 12 and the filament 13 can be increased. In addition, since the nip pressure can be reduced, the base sheet 11, 12 is not easily damaged, and the texture inherent to the base sheet 11, 12 is more unlikely to be impaired.

  In this embodiment, it is preferable to set the clearance of the first stage nip roll to be equal to or greater than the sum of the thickness of the extruded resin material, the thickness of the base sheet, and the thickness of the belt-shaped member. By performing such an operation, in the first-stage nip roll, damage to the filament 13 is reduced, and inconveniences such as breakage of the filament 13 are less likely to occur. In the second-stage nip roll, the filament 13 and the base material sheets 11 and 12 are reliably bonded, and the bonding force between them is increased.

  As the belt-like member 32, for example, a metal material such as steel and stainless steel, or a resin material such as polyethylene terephthalate, polyvinyl chloride, polyurethane, nylon, and a composite material thereof can be used.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to this embodiment. For example, in each of the embodiments described above, three sub-rolls are used, but instead of this, only two sub-rolls may be used, or four or more sub-rolls may be used.

  In the present invention, among the nip rolls installed in multiple stages, the nip pressure in the second stage may be made higher than the nip pressure in the first stage. When three or more nip rolls are installed, the nip rolls in the third and subsequent stages are used. The pressure may be higher or lower than the second stage nip pressure. Alternatively, the nip pressure after the third stage may be the same as the nip pressure at the second stage. From the viewpoint of further increasing the bonding strength between the filament 13 and the base material sheets 11 and 12, it is preferable to increase the nip pressure in the later stage.

  Moreover, in the said embodiment, although the resin material extruded from die | dye was the form of the filament, you may extrude the resin material in the form of a film instead of or in addition to this.

  Furthermore, in the said embodiment, although the resin material extruded from the die | dye was bonded between the two base material sheets 11 and 12, it replaced with this and it extrude | pushed out from one die | dye and die | dye. The resin material may be bonded together.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
A composite sheet having stretchability was manufactured using the apparatus shown in FIGS. The main roll 18 was made of metal. Two sub rolls were used, and the first sub roll 19a and the second sub roll 19b were made of silicon rubber rolls. As the first and second substrate sheets 11 and 12, air-through nonwoven fabrics having a basis weight of 19 g / m ² and a thickness of 0.016 mm (a calculated thickness with a specific gravity of 1.16 from the basis weight) were used. The constituent fiber of this nonwoven fabric was a core-sheath type composite fiber (core: PET, sheath: PE) having a diameter of 19 μm, a maximum elongation of 180%, and a fiber length of 44 mm. As the raw material resin for the filament 13, an elastomer made of SEPS resin (weight average molecular weight 50,000, MFR 60 g / 10 min (230 ° C., 2.16 kg)) was used. The spinning conditions were a temperature of the spinning head 17 of 310 ° C., a diameter of the spinning nozzle 16 of 0.4 mm, a pitch of the spinning nozzle 16 of 1 mm, and a draw ratio of 11 times. The diameter of the filament 13 was 0.12 mm. The apparent basis weight (filament weight in the sample / sampling sheet area) of the filament was 10 g / m ² . The total thickness of the materials was 0.152 mm. The clearance of the first stage nip roll was 0.3 mm, and the clamping pressure was 70 N / cm. This clearance was a value greater than or equal to the sum of the diameter of the filament 13 and the thickness of the base sheet. There was no clearance of the second-stage nip roll, solid pressing (rubber roll was crushed), and the clamping pressure was 50 N / cm. The elastic expression processing of the composite sheet was performed using an elastic expression device 22 provided with a pair of tooth space rolls 20 and 21 in which teeth and tooth bottoms were alternately formed in the axial length direction. The pitch between teeth and the bottom of each tooth was 2.0 mm (the pitch P between teeth in the meshed state was 1.0 mm). The pushing amount of the upper and lower tooth gap rolls was adjusted, and the composite sheet 10 was stretched in the extending direction of the filament 13 at a stretch ratio of 3.3 times. As a result, a composite sheet 10 having a basis weight of 47 g / m ² that expands and contracts in the extending direction of the elastic filament 13 was obtained.

[Comparative Example 1]
In Example 1, only the first stage nip roll was used, and the second stage nip roll was not used. The clearance of the first stage nip roll was 0.3 mm, and the clamping pressure was 70 N / cm. Other than that was carried out similarly to Example 1, and obtained the composite sheet which has a stretching property.

[Comparative Example 2]
In Example 1, only the first stage nip roll was used, and the second stage nip roll was not used. There was no clearance of the first-stage nip roll, and solid pressing was performed, and the clamping pressure was 70 N / cm. Other than that was carried out similarly to Example 1, and obtained the composite sheet which has a stretching property.

[Evaluation]
In Examples and Comparative Examples, the peel strength between the filament and the base sheet was measured for the composite sheet before the elastic development processing. First, the composite sheet was cut out in a size of 150 mm in the filament extending direction and 25 mm in a direction orthogonal thereto, to obtain a test piece. About 30 mm was peeled off from the end of the test piece, and the test piece was mounted on a tensile tester (Orientec Co., Ltd., Tensilon, RTC1210A) with a chuck distance of 30 mm. The test piece was peeled 100 mm in the extension direction at a speed of 300 mm / min. The average value of the five maximum point loads during peeling was defined as the peeling strength. The results are shown in Table 1 below.

In the examples and comparative examples, the texture of the composite sheets before the elastic development processing was evaluated. Evaluation was sensory evaluation by 10 female monitors. In a dark box where the composite sheet was not visible under an environment of a temperature of 25 ° C. and a humidity of 40%, the monitor was touched with the composite sheet, and the texture was evaluated according to the following criteria. The average score (rounded to the nearest decimal point) of 10 monitors was used as the texture evaluation score. The results are shown in Table 1 below.
5 points: good texture 4 points: slightly good texture 3 points: normal 2 points: slightly bad texture 1 point: poor texture

  As is apparent from the results shown in Table 1, it can be seen that the sheets obtained in the examples have a good texture despite the high peel strength. On the other hand, it can be seen that the sheet obtained in Comparative Example 1 has a good texture but low peel strength. On the contrary, the sheet obtained in Comparative Example 2 has a high peel strength but is inferior in texture.

It is a partially broken perspective view which shows an example of the composite sheet manufactured according to the method of this invention. It is a schematic diagram which shows the apparatus used suitably for the manufacturing method of this invention. It is a schematic diagram which shows the extending | stretching apparatus of a composite sheet. It is a schematic diagram which shows the state by which a composite sheet is extended | stretched with the extending | stretching apparatus shown in FIG. It is a schematic diagram which shows another apparatus used suitably for the manufacturing method of this invention.

Explanation of symbols

10 Composite sheet 11, 12 Base sheet 13 Filament 18 Main roll 19a, 19b, 19c Sub roll

Claims (5)

In a method of manufacturing a composite sheet by passing a resin material extruded from a die between nip rolls together with a substrate sheet being conveyed, and bonding the substrate sheet and the resin material together,
Nip rolls are installed in multiple stages, and the nip pressure in the second stage is higher than the nip pressure in the first stage .
A method for producing a composite sheet, wherein the clamping pressure of the first stage nip roll is 1 to 150 N / cm, and the clamping pressure of the second stage nip roll is 5 to 200 N / cm .   The method for producing a composite sheet according to claim 1, wherein the clearance of the first stage nip roll is set to be equal to or greater than the sum of the thickness of the extruded resin material and the thickness of the base sheet.   The belt-shaped member that sequentially passes between the nip rolls of each stage, and sequentially passes the complex between the nip rolls of each stage while conveying the complex in which the resin material is sandwiched between the base sheet. A method for producing a composite sheet. The method for producing a composite sheet according to claim 3 , wherein the clearance of the first stage nip roll is set to be equal to or greater than the sum of the thickness of the extruded resin material, the thickness of the base sheet, and the thickness of the belt-shaped member. The manufacturing method of the composite sheet in any one of Claim 1 thru | or 4 which extrudes resin material in the state of a filament or a film.

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