JP2008179920A - Smooth lightweight board material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a smooth lightweight board having a low density but having nearly uniform resin filling ratio in the direction of thickness, a high resin filling ratio also at the center region to attain excellent bending behavior, free from abrupt stress drop even if being bent beyond a bending level exhibiting maximum bending stress and having excellent surface smoothness and light weight. <P>SOLUTION: The smooth lightweight board material is composed mainly of a nonwoven fiber fabric containing 80-100 mass% wet-heat bondable fiber, has a thickness of 0.5-6.0 mm and an apparent density of 0.2-0.5 g/cm<SP>3</SP>and satisfies the requirements that (1) the filling ratio of the fiber resin in the cross-section is 40-80%, (2) the average center-line roughness is ≤100 μm on at least one surface, and (3) the maximum bending stress is ≥1.0 Pa at least in one direction and the bending stress at the bending level corresponding to 1.5 times the maximum bending stress is ≥1/3 of the maximum bending stress. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a board material for partitioning the interior of a container such as a bag mainly for carrying or moving and dividing it into a plurality of rooms and reinforcing its form, and more specifically, as a partition material A smooth lightweight board material having a form of a board-like sheet that balances the holding property, the hardness as a reinforcing sheet material, and the light weight to minimize the weight increase due to the use of a partition material (sometimes referred to simply as a board). About.

Conventionally, various sheet-like materials such as synthetic fiber nonwoven sheets, synthetic resin sheets, and synthetic resin foams have been proposed as reinforcing sheets for containers mainly intended to be carried, such as bags.
However, when a synthetic resin sheet, synthetic resin foam, etc. are bent, they are easily damaged by a slight bending operation or bent with a clear crease even if they are not damaged, resulting in extremely low stress. Resulting in. Moreover, the crease remains in the form of permanent distortion. Furthermore, if bending is repeated by applying force to the portion thereafter, there is a problem that the portion is cracked and easily broken from there.

  Therefore, in many cases, a method is used in which a non-woven sheet is used as a basic structure and the defects of the non-woven sheet are eliminated by impregnating the non-woven sheet with a resin. For example, Patent Document 1 discloses that a web is impregnated with an organic solvent-based dispersion containing an unsaturated polyester resin and foamable thermoplastic microspheres at 20 to 200% by weight of the web and dried. There has been proposed a lightweight composite material in which thermoplastic sheets of ˜50 μm are laminated and thermoformed to a predetermined thickness. However, the present invention does not mention the presence or absence of the adhesion between the fibers as well as the presence or absence of influence on the effect expression based on the mutual relationship between the constituent fibers of the nonwoven sheet, and the fibers are simply impregnated. It only functions as a resin holder. For this reason, it becomes easy to express the fold accompanying permanent set when bent.

  Further, Patent Document 2 proposes a reinforcing sheet for light work product obtained by heating and pressurizing a non-woven fabric in which a polyester fiber and a low melting point fiber having a smaller fiber diameter are mixed. However, in this invention, it is stated that any conventionally known method is adopted as a method for expressing hardness by fiber fusion, and heat is applied to the surface to heat, and the surface is smoothed by a flat plate or a roller. However, it does not devise a method to actively bond the fibers inside the nonwoven fabric and make the bonding degree in the thickness direction uniform, so it promotes the fusion of fibers near the sheet surface and secures the hardness. Will do. That is, a remarkable fiber fusion is expressed in the sheet surface region, and the filling rate in the central portion in the thickness direction is extremely low. When such a sheet is gradually bent, it tends to develop a bent part having permanent distortion near the deepest part of the bend, and it is easily guessed that when the sheet is bent beyond the peak stress, a significant stress drop occurs. it can.

  Furthermore, Patent Document 3 describes a hard board having a thickness of 1000 μm or more in which polyvinyl alcohol-based fibers having a melting temperature in water of 100 ° C. or more are joined together by a polyvinyl alcohol-based binder, and is lightweight, highly rigid, and environmentally friendly. Proposals have been made on hardboards that can be easily discarded, methods for manufacturing the same, and partitions suitable for bags, shelves, and the like. However, since the board of the present invention uses polyvinyl alcohol binder fibers having a melting temperature of 65 ° C. or higher, there is a high possibility that the board will collapse when exposed to water having a temperature higher than this temperature. Furthermore, since there has been no contrivance to make the degree of positive fiber adhesion inside the nonwoven fabric uniform and the degree of adhesion in the thickness direction, as in Patent Document 2, it is easy to bend at a specific position when bent. It can be easily assumed that the bent portion is likely to remain as a permanent strain in a bowl shape, and that a significant decrease in stress occurs when bent beyond the peak stress.

JP 2001-232705 A JP 2006-207049 A JP 2001-355171 A

  The present invention has been made in view of the above-described problems, and maintains lightness, rigidity, and surface smoothness by maintaining a high level of fiber adhesion in the central portion in the thickness direction of the reinforcing partition, Especially in bending behavior, it does not show an extreme decrease in stress even after showing a stress peak, and it is bent without a permanent distortion up to a deeper bending angle, The object is to provide a smooth and lightweight board material useful for reinforcement.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the present invention is a board material mainly composed of a fiber nonwoven fabric containing 80 to 100% by mass of wet heat adhesive fiber, and has a thickness of 0.5 to 6.0 mm and a thickness of 0.2 to 0.7 g / cm ³ . Having an apparent density,
(1) Filling ratio of fiber resin in cross section is 40-80%
(2) On at least one surface, the average center line roughness is 100 μm or less. (3) The maximum bending stress in at least one direction is 1.0 N / 25 mm or more, and the bending amount is 1.5 times the maximum bending stress. The present invention relates to a smooth and lightweight board material having a bending stress of 1/3 or more of the maximum bending stress.

  The smooth and lightweight board material of the present invention maintains a desired level without sacrificing hardness and stiffness, realizes excellent lightness, and is less likely to bend with permanent distortion when bent greatly. By securing the bending behavior, it is possible to reinforce moss and portable accessories and to classify the capacity. A particularly suitable application is school nursery rhymes represented by school bags. These bags are often handled almost every day for several years at school, with textbooks in them, and can be used with heavy loads, such as pushing large objects or underlaying heavy objects. High nature. Therefore, the smooth and lightweight board material of the present invention does not break even when a somewhat excessive force is applied, and causes permanent deformation even when an article having a shape different from the shape of the frontage is pushed in with a slight load. It is possible to maintain the shape without loss and to obtain the characteristics of returning to the original shape when these are removed.

  The smooth and lightweight board material of the present invention is obtained by driving high temperature steam into a fiber web using mainly wet heat-adhesive fibers as raw material fibers so that the fibers form each wet heat-adhesive fiber. The fibers are bonded at their intersections at a temperature equal to or lower than the melting point, and the bonded state is distributed substantially uniformly in the thickness direction, thereby ensuring light weight and high bending stress. In addition, it bends without bending when it is gradually bent, and even if it bends past the point showing the maximum bending load, it keeps without causing an extreme load drop and tries to recover when the load is released. In addition to having the property of preventing the occurrence of clear folds with distortion (hereinafter sometimes referred to as “difficult to break”), it also ensures surface smoothness at the same time.

  As the wet heat adhesive resin constituting the wet heat adhesive fiber used in the present invention, a resin component that is softened with hot water of about 95 to 100 ° C. and is self-adhesive or adheres to other fibers is preferable. For example, acrylamide is one component. And copolymers such as polylactic acid and ethylene-vinyl alcohol copolymer. Also included are polyurethane-based, polyolefin-based, polyester-based, polyamide-based, styrene-based elastomer resins and the like that can flow or easily deform to develop an adhesive function at a temperature that can be easily realized by high-temperature steam. Among these, an ethylene-vinyl alcohol copolymer can be particularly preferably used.

  Here, as the ethylene-vinyl alcohol copolymer which is a wet heat adhesive fiber or wet heat adhesive component, a copolymer obtained by copolymerizing 10 to 60 mol% of ethylene units with polyvinyl alcohol is preferably used. In particular, a copolymer obtained by copolymerizing 30 to 50 mol% of ethylene units is preferable in order to ensure the post-processability of the board material. The vinyl alcohol portion preferably has a saponification degree of 95 mol% or more. Due to the large number of ethylene units, wet heat adhesion can be obtained without exhibiting hot water solubility. The degree of polymerization can be selected as necessary, but is usually about 400 to 1500.

  When the ethylene unit content is less than 10 mol%, the ethylene-vinyl alcohol copolymer easily swells and gels with low-temperature water, and may change its form once wetted with water. . On the other hand, if it exceeds 60 mol%, the hygroscopicity is lowered and fiber fusion due to wet heat becomes difficult to develop, so that practical hardness may not be ensured.

  The cross-sectional shape of the wet heat-adhesive fiber made of these resins is not particularly limited, and is not limited to a round shape or a typical cross-sectional shape that is a general solid cross-sectional shape, but may have various cross-sectional shapes such as a hollow cross-sectional shape. Can do. Furthermore, when it is difficult to achieve the purpose with a fiber made only of a wet heat adhesive resin, such as when a higher fiber strength is required, it is preferable to use a composite fiber with another fiber. In the composite form, the wet heat adhesive resin is not particularly limited as long as a part or all of the wet heat adhesive resin is continuously present in the length direction on the fiber surface. For example, a core-sheath type, a sea-island type, a side-by-side type, a multilayer bonding type, a random composite, a radial bonding type, and the like can be given. Or the fiber which coat | covered the resin which has wet heat adhesiveness to the fiber which consists of another fiber-forming polymer may be sufficient. These fibers can be colored by kneading a pigment as necessary.

  In this case, the resin other than the wet heat adhesive resin, or the partner fiber coated with the wet heat adhesive resin can include resin components or fibers made of polyester, polyamide, polypropylene, etc., but heat resistance, dimensional stability In view of the above, polyesters, polyamides and the like having a melting point higher than that of the ethylene-vinyl alcohol copolymer are preferably used.

  Examples of the polyester include terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, α, β- (4-carbophenoxy) ethane, 4,4-dicarboxydiphenyl, 5-sodium sulfoisophthalic acid and the like. Aliphatic dicarboxylic acids such as aliphatic dicarboxylic acids, azelaic acid, adipic acid, sebacic acid or their esters, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, Mention may be made of fiber-forming polyesters composed of diols such as neopentyl glycol, cyclohexane-1,4-dimethanol, polyethylene glycol and polytetramethylene glycol, and 80 mol% or more of the structural units are ethylene terephthalate units. Is preferred Yes.

  Examples of the polyamide include aliphatic polyamides mainly composed of nylon 6, nylon 66, and nylon 12, and semi-aromatic polyamides. Polyamides containing a small amount of the third component may also be used.

  And when the mass ratio of the wet heat adhesive resin existing on a part and / or the entire surface of the composite fiber exceeds 60%, it becomes impossible to ensure the strength of the fiber part formed by other resins, and as a result It may be difficult to ensure sufficient strength of the composite fiber itself. On the other hand, when the mass ratio of the wet heat adhesive resin is less than 20%, the amount of the wet heat adhesive resin is small, so that it is extremely difficult to hold a continuous resin layer in the length direction. At this ratio, it becomes difficult to form a fiber bundle inside the sheet, so that it is difficult to ensure sufficient surface smoothness and bending strength. This is the same when the wet heat adhesive resin is coated on the fiber.

  When manufacturing a web composed of wet heat adhesive fibers or composite fibers containing wet heat adhesive resin as a component (also referred to as heat adhesive fibers), other fibers may be mixed as necessary. In this case, the mixing ratio of the wet heat adhesive fiber or the composite fiber is 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more. The higher the percentage of wet heat adhesive fibers, the easier it is to finish a hard nonwoven fiber board. When this fiber is less than 80% by mass, the adhesion point between the fibers decreases, and it becomes difficult to ensure sufficient bending strength. Or it becomes difficult to ensure the target smoothness because some fibers are fluffed.

  The fiber to be mixed is not particularly limited. However, when the board of the present invention is thermoformed by later processing, it is possible to express more excellent formability, and therefore, the fiber is made of polyester, polyamide, polyolefin, or the like. It is preferably a thermoplastic fiber. Furthermore, a heat-fusible fiber is more preferable so that more fiber fusion points can be secured during molding. In this case, a core-sheath type composite fiber in which isophthalic acid-modified polyester, polyethylene-modified polypropylene or polyethylene is used as a sheath component, and polyester, polyamide, polypropylene or the like is used as a core component is preferably used.

  In order to obtain a board having the lightness and smoothness as the object of the present invention and having excellent bending behavior in a balanced manner using such a fiber web, the arrangement state and adhesion of the fibers constituting the web are described. It is necessary to adjust the state appropriately. That is, when forming the fiber web, it is desirable that the constituent fibers are arranged so as to intersect each other while being arranged substantially parallel to the fiber web surface. In the obtained smooth and lightweight board of the present invention, the fibers are fused at the fiber intersections, and the fibers other than the intersections are fused in a bundle of several to several tens at the portion where the fibers are arranged substantially in parallel. It is desirable to form a bundled fused fiber. By forming a structure in which these fibers are fused at the intersections of single fibers, the intersections of bundled fibers, or the intersections of single fibers and bundles of fibers, it has a structure like a “scrum”. Thus, the intended bending behavior and surface smoothness can be expressed. In the present invention, it is desirable that such a structure is distributed substantially uniformly along the surface direction and the thickness direction.

  Here, “almost parallel to the fiber web surface” means that there are repeated portions where a large number of fibers are locally arranged along the thickness direction, such as a needle punched nonwoven fabric. Indicates a state where there is no such thing. More specifically, it refers to a state in which when an arbitrary cross section of the fiber web is observed with a microscope, the existing ratio of fibers continuously extending over 30% or more of the thickness is 10% or less.

  The fibers are arranged in parallel to the fiber web surface because if there are many fibers oriented along the thickness direction (perpendicular to the fiber web surface), the fiber arrangement is disturbed in the surrounding area and is not woven. This is because an unnecessarily large gap is formed in the fiber board, and the bending strength and difficulty of bending of the non-woven fiber board are reduced using this gap as a starting point.

  Therefore, the smooth and lightweight board material of the present invention forms the small gaps by arranging and dispersing the constituent fibers in parallel along the plane direction so that the fibers intersect each other and are bonded and fused at the intersection. In this way, the lightness is ensured and it is difficult to break. Furthermore, as a result, these air gaps can be continued to have an appropriate air permeability.

  Here, in order to express a stronger resistance to breakage, it is necessary to fix the fibers at other portions together with the fiber adhesion at the fiber intersection. For this purpose, it is preferable to form a bundle-like fiber fused in parallel in the length direction at a location where the fibers are arranged in parallel and not intersecting with other fibers. Ideally, it is most preferable to form a bundle of fibers between the intersections while adhering at the intersections where the fibers cross one another.

With such a structure, it is possible to achieve both moderate hardness and deformation followability, the fibers interact with each other, and when bent, they can easily “fold” with permanent distortion. It is difficult to prevent the stress from dropping at once.
In other words, the fiber is not 100% bonded, it has a non-bonded part, and a lot of small voids in the interior make it possible to create a escape space consisting of voids in the board when a strong bending stress is applied. The unbonded fibers move to bend and withstand without bending.

The board material of the present invention is useful for partitioning or reinforcing portable containers such as bags, and for that purpose, it is important to be lightweight. From such a viewpoint, the board material of the present invention has an apparent density of 0.2 to 0.7 g / cm ³ , preferably 0.25 to 0.65 g / cm ³ , and more preferably. 0.3 to 0.6 g / cm ³ . When the apparent density is less than 0.2 g / cm ³ , although it has lightness, it is difficult to ensure sufficient bending hardness and surface hardness. Conversely, when it exceeds 0.7 g / cm ³ , Although it can be secured sufficiently, it is difficult to say that it is a lightweight board material.
In addition, in the application of the present invention, when a thick board material is used, the volume of the bag or container is reduced accordingly, so that a thicker one is not preferable, and is in the range of 0.5 to 6.0 mm. It is preferably 0.5 to 5.5 mm, more preferably 0.6 to 4.5 mm. If the thickness is less than 0.5 mm, it is difficult to ensure the hardness. If the thickness exceeds 6.0 mm, the container space is wasted, which is not preferable.

As described above, the performance of the board material of the present invention depends on the presence of bundled fused fibers in the nonwoven fabric, but each fiber is bonded or fused at a bundle or at an intersection. Therefore, it may be difficult to observe as a single fiber. For this reason, in this invention, the area ratio which the cross section which the fiber in a board cross-section after a process and a bundle-form fiber forms forms, ie, a cross-section resin filling rate, shall be used as a value reflecting this degree of fiber fixation.
In the present invention, in this cross section, the resin filling rate extending from one surface to the opposite surface in the thickness direction (hereinafter referred to as “total thickness filling rate”) is 40 to 80%, preferably 50 to 80%. %, And more preferably 50 to 70%. When the total thickness filling rate is less than 40%, there are too many voids in the board, and it becomes difficult to ensure bending difficulty. Conversely, if it exceeds 80%, a sufficient bending stress can be secured, but this fiber board is unfavorable because it is heavy and difficult to handle.

  Furthermore, in the board material of the present invention, in order to balance the high bending strength, lightness and surface smoothness at a higher level, the constituent fibers are bonded and fused at the bundled fibers or fiber intersections as described above. Are preferably distributed uniformly in the thickness direction without being concentrated as much as possible. As a result, fine voids and passages are secured in the board material, and light weight and air permeability are ensured. Therefore, in order to develop a large bending stress, surface hardness and air permeability with as few contacts as possible, the bonding point is uniform along the thickness direction from the fiberboard surface to the center and the opposite surface. It is preferable that they are distributed.

  Usually, in order to give bending hardness to a thick sheet material, a method of melting the resin by applying pressure and heat from the table by calendering or flat plate heat press, etc., and fusing to high density is common. However, since heat press time is shortened when processing is performed efficiently while maintaining sufficient lightness, resin fusion on the sheet surface is remarkably promoted, and fibers in the central part in the thickness direction are almost fused. It becomes difficult, there is less fiber fusion at the center in the thickness direction, and there are more voids left, so even if sufficient hardness is obtained, permanent deformation will occur at the bend amount when bent When the bending amount of the maximum load is exceeded, the weight is almost zero. On the other hand, if the resin is sufficiently fused in the center in the thickness direction of the sheet by heating and pressing for a long time, the bending hardness of the sheet after processing can be secured, but the resin flows by heating for a long time. Thus, there is a high risk that the sheet form will collapse, and even if the form can be ensured well, the product will be very dense and inferior in weight.

  Therefore, in the board material of the present invention, when the board cross-section is divided into three equal parts along the thickness direction, the fiber cross-section filling rate in the central region (hereinafter referred to as “center filling rate”), that is, In the area ratio of the fiber cross section in the board cross section, the value is preferably in the range of 30% to 80%. More preferably, it is 30%-70%, More preferably, it is 40-70% or less. The fiber cross-section filling rate (“full thickness filling rate” and “center filling rate”) referred to in the present invention is calculated by the method described later.

  In order to represent the bending behavior of the board material of the present invention, it was used in accordance with JIS K7017 “Fiber Reinforced Plastics—How to Obtain Bending Properties” by measuring the repulsive force of the sample, that is, the bending load, which is generated when the sample is bent gradually. . That is, it can be said that the larger the bending load is, the harder the structure is, and furthermore, the larger the amount of bending until the measurement object is broken, the better the structure is bent.

  The board material of the present invention needs to have a maximum bending stress in at least one direction of 1.0 N / 25 mm or more, preferably 2.0 to 30 N / 25 mm, and more preferably 5 to 15 N / 25 mm. is there. If this maximum bending stress is less than 1.0N / 25mm, it will easily break due to its own weight and slight load when used as a board material. The body as a material is lost. Further, in order to obtain a hardness exceeding 30 N / 25 mm, it is necessary to increase the density of the board, and there may be cases where it is difficult to ensure light weight.

  Looking at the correlation between the bending amount and the bending stress caused by the bending amount, the stress increases as the bending amount increases. In the board material of the present invention, when the bending amount inherent to the measurement sample is reached, the stress gradually decreases thereafter. That is, it shows a correlation that draws an upwardly convex parabolic curve. The nonwoven fiber board of the present invention is also characterized by having a so-called “stickiness” without causing a rapid stress drop even when attempting to bend beyond the maximum bending stress (bending load peak). One. As an index representing such “stickiness”, the present inventors used the bending stress remaining in a state exceeding the bending amount (displacement) at the peak of bending stress. That is, the non-woven fiber board of the present invention has a stress when bent to a displacement of 1.5 times the bending amount indicating the maximum bending stress (hereinafter sometimes referred to as “1.5 times displacement stress”). 1/3 or more of the maximum bending stress is maintained, preferably 2/5 or more, more preferably 3/5 or more.

  This is related to the easiness of the development of permanent strain when bent. Usually, a plate with voids inside has the property that the stress rapidly decreases when bending occurs with permanent strain. Therefore, it is used as a guide. For example, a plate with a high value will not enter if it is too hard, such as when it is used as a bowl, or when the contents are packed in a form different from that of the storage part of the bowl. If it breaks and breaks, it will be a problem. While maintaining the shape of the ridge, the shape of the partition material itself is maintained while being appropriately deformed so as not to be destroyed, and the properties of returning to the original state after taking out the contents are exhibited.

  Furthermore, it is important that at least one surface of the board material of the present invention is smooth. As an index indicating the smoothness, the center line average roughness Ra is calculated by detecting the displacement of the vertical movement that occurs in accordance with the unevenness of the surface of the object when the needle in contact with the surface of the object is moved parallel to the surface. The value was used. In the present invention, this value is preferably 100 μm or less. More preferably, it is 50 micrometers or less, Most preferably, it is 20 micrometers or less. In the case of a bag or the like, the surface is generally covered with a cloth, film, leather or the like, and in this case, if this value exceeds 100 μm, the surface covering of the material covering the surface is uneven. Appears as a trace, it appears that there are wrinkles and irregularities on the surface material at the corner, which is not preferable because of poor appearance. In addition, there is a case where the partition material is used in an exposed state without performing such treatment on some members for the purpose of weight reduction and price reduction. Things are necessary.

Next, the board | substrate material manufacturing method of this invention is demonstrated.
The above-mentioned wet heat adhesive fiber or composite fiber containing wet heat adhesive resin as a component is made into a fiber web, and the fiber is fixed to obtain a target board. For web formation, the spunbond method and the melt blow method are used. A direct method may be used, or a web may be formed by using a dry method such as a card method or an air lay method using staple fibers. As the staple fiber web, a random web, a semi-random web, a parallel web, a cross-wrap web, and the like are used. As will be described later, a semi-random web that can easily secure bundled fiber fusion required in the present invention. Or a parallel web is preferable.

  The fiber web formed in this way is sent to the next process by a belt conveyor, and then exposed to a high-temperature steam (high-pressure steam) flow, whereby the board material of the present invention is obtained. The belt conveyor used here is not particularly limited as long as it can be subjected to high-temperature steam treatment while compressing the fiber web used for processing to a desired density, and an endless conveyor is suitable. Used.

  A steam injection device for supplying steam to the web is mounted in one conveyor and supplies steam to the web through a conveyor net. A suction box may be attached to the opposite conveyor. In this case, excess steam that has passed through the web can be sucked and discharged. Furthermore, in order to steam the front and back of the web at the same time, a suction box is installed on the downstream side of the conveyor where the steam injection device was installed, and a steam injection device is installed in the opposite conveyor May be. If there is no downstream steam injection device and suction box, if the front and back of the fiberboard are to be steamed, it can be substituted by reversing the front and back of the fiberboard once treated and passing through the processing device again.

  The endless belt used for the conveyor is not particularly limited as long as it does not hinder the conveyance of the web or the high-temperature steam treatment. However, when high-temperature steam treatment is performed, the surface shape of the belt may be transferred to the board surface obtained depending on the conditions. In particular, when it is desired to obtain a board having a flat surface, a net with a fine mesh may be used. In this case, the upper limit is about 90 mesh. Finer mesh than this is not preferable because it has low air permeability and is difficult for vapor to pass through. The belt material is preferably a mesh belt made of metal, heat-treated polyester, polyphenylene sulfide, or heat-resistant resin such as polyarylate or wholly aromatic polyester from the viewpoint of heat resistance against steam treatment.

  Since this high-temperature steam is an air flow, the fiber in the web that is the object to be treated enters the inside of the web without being largely moved (as in the water entangling process or the needle punching process). It is considered that the vapor flow enters the inside of the web so that the vapor flow efficiently covers the surface of each fiber existing in the web in a wet heat state, thereby enabling uniform thermal bonding and heat fusion. In addition, since this treatment is performed in a very short time under a high-speed air stream, the fiber surface becomes hot and humid, but the heat and moisture conduction to the inside of the fiber is not so much, so it is treated by the pressure and heat of the high-temperature steam. Wet heat bonding is completed before deformation that causes the entire fiber to collapse occurs.

In order to ensure the light weight and bending strength of the board material of the present invention, when the high temperature steam is supplied to the web and processed, the processed web is subjected to a desired apparent density between the conveyor belt or the rollers, that is, It is important to expose to high temperature steam in a state compressed to a density of about 0.2 to 0.7 g / cm ³ . In particular, when trying to obtain a high-density board, it is necessary to compress the web with sufficient pressure when processing with high-temperature steam. Furthermore, by securing an appropriate clearance between the rollers or between the conveyors, it is possible to match the target thickness and density. In the case of a conveyor, since it is difficult to compress the web at a stretch, it is preferable to set the belt tension as high as possible and gradually narrow the clearance from the upstream of the steam treatment point. In addition to this, by adjusting the steam pressure and the processing speed, it is processed into a board having a desired bending hardness, surface hardness, light weight and air permeability.

The nozzle for injecting the steam may be a plate or die in which predetermined orifices are continuously arranged in the width direction, and may be arranged so that the orifices are arranged in the width direction of the web to be supplied. At this time, the number of the orifice rows may be one or more, and a plurality of rows may be arranged in parallel. Of course, a plurality of nozzle dies having a single orifice array may be installed in parallel.
For example, when using a type of nozzle in which an orifice is formed in a plate, the thickness of the plate is mainly about 0.5 to 1.0 mm. In this case, the diameter and pitch of the orifice are not particularly limited as long as the target fiber can be fixed, but usually, those having a diameter of 0.05 to 2.0 mm are often used. Is 0.1 to 1.0 mm, more preferably 0.2 to 0.5 mm. On the other hand, the pitch of the orifices is usually 0.5 to 3.0 mm in many cases, but is preferably 1.0 to 2.5 mm, more preferably 1.0 to 1.5 mm.

Further, the high-temperature steam used for fiber bonding is not particularly limited as long as the target fiber fixation can be realized, and may be set depending on the material and form of the fiber to be used, but steam at a pressure of 0.1 MPa to 2.0 MPa is used. It is preferably used, more preferably 0.2 to 1.5 MPa, and still more preferably 0.3 to 1.0 MPa. If the pressure of the steam is too high or too strong, the fibers forming the web will move, causing disturbance of the formation, and the fibers will melt too much to partially retain the fiber shape. May occur.
Also, if the pressure is too weak, it will not be possible to give the workpiece the amount of heat necessary for fiber adhesion or fusion, or steam will not penetrate the web, causing fiber fusion spots in the thickness direction, etc. The above problems occur, and it is easy to cause problems such as difficulty in controlling the uniform ejection of steam from the nozzle.

However, in order to impart surface smoothness to the board material of the present invention, a slight fiber fusion is expressed by treating the web with steam at a slightly lower pressure in advance, and afterwards between the web thickness adjusting rolls. A desired thickness and surface smoothness are imparted by passing the original high-temperature steam immediately after passing through. At this time, it is necessary to secure the clearance between the web thickness adjustment rolls according to the thickness of the target product and to compress the web on which the sent fibers are temporarily fixed to the thickness of the target product. It is.
The pressure of the steam for temporarily fixing the fiber is a pressure that can maintain the form so that the thickness does not greatly recover after passing through the thickness adjusting roll, and is particularly limited if it is lower than the pressure at the time of original fiber fixing. However, it is preferably in the range of 0.05 to 1.2 MPa.

  After the fibers of the fiber web are partially wet-heat bonded in this way, moisture may remain on the resulting board and must be dried as necessary. As for drying, it is necessary that the board surface in contact with the heating element for drying maintains the fiber form without forming a film after drying, and any method can be used as long as this can be achieved. For example, you may use a large-scale drying facility such as a cylinder dryer or a tenter that is used for drying nonwoven fabrics. When it is at a dryable level, a non-contact method such as far-infrared irradiation, microwave irradiation, or electron beam irradiation, or a method using hot air is preferred.

  Necessary after drying the board in a hot air oven, winding it, and then heating the raw material with hot air, etc., then controlling the thickness and improving the smoothness by processing with a cold calendar with clearance Cut into a single plate in size.

If necessary, the board made at this stage is passed between rollers with clearance, and the surface is smoothed by calendering, and controlled to a certain thickness. It is also possible to give a design property to a board product obtained by giving predetermined conveyor patterns, letters, pictures, etc. to the conveyor belt and transferring them.
Further, it can be laminated with other materials or formed into a desired form by molding.

  Furthermore, in order to further improve the surface smoothness and to impart the intention, it is also possible to coat a resin or coat a film on the board surface. Since the surface of the board is smooth, the resin coat and film can be easily laminated.

  In the case of a resin coat type, the method of the resin coat is not particularly limited as long as this purpose is achieved. For example, the resin coat type is uniformly applied to the surface of the board by a spray coater, a gravure coater, a roll coater, etc. If necessary, the target board material is obtained by smoothing the surface using a calendar process.

  The resin liquid to be coated on the surface is not particularly limited as long as it can express the effect of improving the surface smoothness of the board material of the present invention, a thermosetting resin liquid, a modified thermosetting resin liquid, Alternatively, a mixed resin liquid obtained by mixing a thermoplastic resin with a thermosetting resin or the like can be used. Examples include melamine resins, urea resins, urea-melamine resins, phenol resins, polyester resins, epoxy resins, acrylic resins, vinyl acetate resins, or modified products and mixtures of these resins. it can. Furthermore, these resin liquids are preferably aqueous such as emulsions and aqueous solutions from the standpoints of resin handling and working environment in processing.

These resins need to be coated after being controlled to ensure a stable form of the coating layer, such as adjusting the viscosity of the resin by dissolving in water or an organic solvent as necessary. Depending on the type, a solvent-free resin ratio of 100% can also be used. However, in many cases, if the resin content is less than about 50% by weight, the curing time becomes longer and the productivity becomes worse, or the resin shrinks at the time of curing and the production becomes worse. Warpage is likely to occur. In particular, when applying in the form of an aqueous emulsion or aqueous solution, this tendency is remarkable, so care must be taken. On the other hand, when the resin content exceeds 80% by mass, uniform coating treatment on the board surface becomes difficult depending on the type of resin used, and therefore 55% by mass to 80% by mass is usually desirable.
Further, the amount of resin coating, it is difficult to form a stable resin layer on the surface insufficient amount of resin is less than 20 g / m ^2, whereas the formation of the coating layer exceeds 200 g / m ² is it is easy, with increasing risk of causing cracking or peeling of the coating resin, so productivity is uneconomical decreases, it is desirable to coat a 20g / m ² ~200g / m ² degree.

  Furthermore, a resin film can be bonded to the board surface for the purpose of reinforcing or improving the appearance and ensuring smoothness.

As a resin film to be bonded, a film made of various conventionally known resins such as a film made of a polyester resin, a polyolefin resin, a polyurethane resin, a polystyrene resin, a polyvinyl chloride resin or the like, as long as the object and effect of the present invention are not impaired. However, in order to prevent the user from feeling uncomfortable in the hardness, stiffness balance, appearance, etc. of the board to be bonded, the same type of resin as the fiber used for the board is preferable. Moreover, by using the same kind of resin, a more preferable result can be given with respect to the adhesion between a board and a resin film described later. Further, the design can be imparted by a method such as printing or coloring before or after the resin film is bonded to the board.
The basis weight of the resin film to be bonded is preferably as thin as possible so as not to impair the lightness of the board, but if it is too thin, it is easily affected by fine irregularities on the board surface, and preferably 10 to 50 μm, more preferably It is good to select in the range of about 15-30 micrometers.

  As a method of adhering the resin film to the board surface, it is possible to use an ethylene-vinyl acetate copolymer resin, a polyolefin resin, a polyamide resin, a hot melt resin such as a polyester resin, a crosslinked type such as an epoxy resin or a urethane resin, or a moisture curing type. , Reactive resin such as UV curable type, or silicon resin, chloroprene rubber, etc., are selected as appropriate from the viewpoint of adhesion between the resin film and the board, and used as an adhesive resin. Adhesive resin for either resin film or board Conventionally known methods such as a method of continuously coating and adhering them and a method of sandwiching a film-like or nonwoven-like adhesive resin between the resin film and the board can be employed. As the state of the adhesive resin at the interface between the resin film and the board, a discontinuous equidot shape, a continuous film shape, a nonwoven fabric shape, or the like can be obtained by the above-described method. If the board application is particularly lightweight, the resin film to be bonded to the board surface must be thin, so the smoothness of the board is more important and the smoothness can be fully utilized. Thus, a method in which various hot melt resins are continued in the form of a film or a nonwoven fabric at the interface between the board and the resin film is the most preferable method.

  The use of the board material of the present invention, in particular, the partitioning material for cocoons, is also an important factor in design, so it may be necessary to color the fibers as necessary, and coloring by original or dyeing. You can also. Alternatively, for the purpose of ensuring the design of the surface, films decorated with various characters or patterns may be bonded together, or a colored resin may be coated on the board surface.

  As described above, the board material of the present invention has extremely high bending stress and surface hardness while having a hardness and stiffness sufficient for light work products and a low density similar to that of a general nonwoven fabric. In addition, it also has breathability, it is possible to give lightness, smoothness, and even design, and as a secondary effect, the boards and between the board and other materials are stacked Excellent post-processability such as bonding and sewing. Therefore, it is used for partitioning and reinforcing sheets for general goods such as bags, wallets, notebooks, etc. that are often carried on a daily basis, clothing such as collars and belts, boxes for storing decorative items, etc. It can be preferably used. Among them, there are miscellaneous goods such as handbags, shoulder bags, backpacks, etc. In addition, in a main body such as a business bag or a suitcase, it can be suitably used not only for a reinforcing material in an unexposed portion but also for an exposed member such as a partition material because it has an excellent appearance.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In addition, each physical-property value in an Example was measured with the following method.

(1) Melt index (MI) of ethylene-vinyl alcohol copolymer
According to JIS K6760, it measured using the melt indexer on the conditions of 190 degreeC and a 2.16kg load.

(2) Fabric weight, thickness, and apparent density Fabric weight and thickness were measured according to JIS L1913, and the apparent density was calculated from these values.

(3) Air permeability According to JIS L1096, it measured by the fragile type method.

(4) Surface smoothness Based on JIS B0601 “Definition and display of surface roughness”, the surface smoothness was measured by “Surf Test 501” manufactured by Mitutoyo Corporation. The surface roughness in this invention was taken as the average value of the value (RaMD) of the length direction (MD) and the value of the width direction (CD) (RaCD) of a nonwoven fabric-like thing.
Surface roughness (Ra) = (RaMD + RaCD) / 2
At this time, the cut-off value was 0.8 mm and the measurement length was 2.4 mm.

(5) Bending load It measured according to A method (three-point bending method) among the methods as described in JIS K7017. At this time, a measurement sample having a width of 25 mm × 80 mm was used, the distance between fulcrums was 50 mm, and the measurement was performed at a test speed of 2 mm / min. In the present invention, the maximum stress (peak stress) in this measurement result chart is defined as the maximum bending stress. In addition, the bending stress measurement was measured about MD direction and CD direction. Here, the MD direction refers to a state in which the measurement sample is collected so that the web flow direction (MD) is parallel to the long side of the measurement sample, while the CD direction refers to the web with respect to the long side of the measurement sample. A state in which a measurement sample is taken so that the width direction (CD) is parallel.

(6) 1.5 times displacement load In the measurement of the bending stress in (5), the load when the bending amount (displacement) indicating the maximum bending load is exceeded and further bending to 1.5 times the displacement is continued. The displacement load was 1.5 times.

(7) Bendability evaluation In the bending load test of (5), after bending to a bending displacement of 10 mm, the sample is opened, the bent part is visually observed, and traces remain even if the sample is stretched straight, such as folds and wrinkles. It was determined whether or not deformation occurred.

(8) Cross-section resin filling rate Using a scanning electron microscope (SEM), a photograph of the board cross-section magnified 100 times was taken. Trace paper was overlaid on this photograph, and the photographed area and fiber (bundle) cross section were traced using transmitted light.
Using this image analyzer (manufactured by Toyobo Co., Ltd.), the trace figure is taken into a computer from a CCD camera, binarized, and the percentage of the fiber cross-sectional area in the observed cross-sectional area is calculated and expressed as a percentage. It was.
At this time, an average value at three arbitrary locations in a region corresponding to an area of 1 mm ^{2 in} a cross section extending from one surface to the opposite side in the thickness direction was defined as “total thickness filling rate”.
Also, the board cross-section is divided into three equal parts in the thickness direction, and the average value at any three locations for the area corresponding to the area of 1 mm ^{2 at} the center of each area (surface, center, opposite surface) divided into three equal parts. Was defined as “center filling rate”.
However, even when only a part of the fiber cross section was shown in the observation area of each photograph, the portion included in the observation area was measured as the fiber cross-sectional area.

As the wet heat adhesive fiber, the core component is polyethylene terephthalate, and the sheath component is an ethylene-vinyl alcohol copolymer (ethylene content 44 mol%, saponification degree 98.4 mol%, core-sheath mass ratio = 50/50). A core-sheath type composite staple fiber (manufactured by Kuraray Co., Ltd., “Sophista”, 3 dtex, 51 mm length) was prepared.
Using 100% by mass of the core-sheath type composite staple fiber, a card web having a basis weight of about 300 g / m ² was produced by a card method.
The card web was transferred to a belt conveyor equipped with a 50 mesh, 500 mm wide polycarbonate endless net.

The belt conveyor is composed of a pair of conveyors, an upper conveyor and a lower conveyor, and a metal roll for adjusting the web thickness (hereinafter referred to as a web thickness) on the upstream side from the steam injection nozzle located at the middle part of the conveyor belt on both the lower and upper conveyors. Each may be abbreviated as an adjustment roll). The lower conveyor has a flat shape on the upper surface, that is, the surface through which the web passes, and the upper conveyor has a shape in which the lower surface is bent along the web thickness adjusting roll, and the web thickness adjusting roll of the upper conveyor is It arrange | positions so that it may pair with the roll for web thickness adjustment of a lower conveyor.
Further, the upper conveyor can be moved up and down, whereby the distance between the web thickness adjusting rolls of the upper conveyor and the lower conveyor can be adjusted to a predetermined interval. Furthermore, the upstream side of the upper conveyor process is bent at an angle of 30 degrees (relative to the lower surface of the upper conveyor downstream of the process) with respect to the downstream part, with the web thickness adjusting roll as the base point, and the downstream part is the lower side It is arranged to be parallel to the conveyor. When the upper conveyor moves up and down, it moves while keeping this parallel.

  Each of these belt conveyors rotates in the same direction at the same speed, and the two conveyor belts and the web thickness adjusting rolls can be pressurized while maintaining a predetermined clearance. This is to adjust the web thickness before steaming by working like a so-called calendar process. That is, the card web fed from the upstream side travels on the lower conveyor, but the interval with the upper conveyor is gradually narrowed before reaching the web thickness adjusting roll. And when this space | interval becomes narrower than web thickness, a web is pinched | interposed between an up-and-down conveyor belt, and it drive | works while being compressed gradually. This web is subjected to steam treatment at a pressure of 0.4 MPa from the lower side as a preliminary treatment so that a lighter fiber adhesion than that of the original sheet is exhibited, and is substantially equivalent to the clearance provided in the web thickness adjusting roll. It is compressed until it reaches the thickness, and at the outlet between these rolls, it is steamed at a pressure of 0.8 MPa from the upper side in this thickness state. After that, it runs while maintaining the thickness at the downstream part of the conveyor. It is structured. Here, the roll for adjusting the web thickness was adjusted to have a linear pressure of 50 kg / cm.

Next, the card web is introduced into the steam jetting device provided in the lower conveyor, and 0.4 MPa of high-temperature steam is jetted from the device so as to pass in the thickness direction of the card web to perform steam treatment. An inventive board was obtained. In the steam injection device, a nozzle was installed in the lower conveyor so as to blow high temperature steam toward the web via a conveyor net, and a suction device was installed in the upper conveyor. Further, another jetting device, which is a combination in which the arrangement of the nozzle and the suction device is reversed, is installed on the downstream side of the jetting direction of the jetting device, and steam treatment is performed on both the front and back sides of the web. .
In addition, the hole diameter of the vapor | steam injection nozzle was 0.3 mm, and this nozzle used what was arranged in 1 row at 1 mm pitch in the conveyor width direction. The processing speed was 3 m / min, and the distance between the nozzle and the conveyor belt on the suction side was 1 mm.
The obtained board had a very hard plate shape, and did not break even when the bending amount exceeding the maximum bending stress was exceeded or bent, and there was no extreme decrease in stress. The results are shown in Table 1. Furthermore, the school bag that uses this board as a partitioning material in the pocket part is lightweight, and even if it is put in a form that pushes it into the pocket part, it will not easily bend with a fold. It was.

Example except that a card web having a basis weight of about 300 g / m ² mixed with 95% by mass of the wet heat adhesive fiber used in Example 1 and 5% by mass of polyethylene terephthalate fiber (1.7 dtex, 51 mm length) was used. In the same manner as in No. 1, a board of the present invention was obtained. The results are shown in Table 1.
Although the obtained board was slightly softer than the board obtained in Example 1, it showed the same bending stress and good bending evaluation results.

Example 1 except that a card web having a basis weight of about 300 g / m ² mixed with 85% by mass of the wet heat adhesive fiber used in Example 1 and 15% by mass of the polyethylene terephthalate fiber used in Example 2 was used. Similarly, the board of the present invention was obtained. The results are shown in Table 1.
The obtained board was softer than the board obtained in Example 2, but showed similar bending stress and good bending evaluation results.

A board was obtained in the same manner as in Example 1 except that the basis weight of the card web was about 150 g / m ² and the distance between the steam nozzle and the suction side conveyor was 0.5 mm. The results are shown in Table 1.
Although this board has a lower basis weight than the board of Example 1, it shows a lower bending stress than the board obtained in Example 1 by ensuring a slightly higher apparent density and resin filling rate. As a partition material, the bending stress without any practical problem and the result of good bending evaluation were shown.

A board was obtained in the same manner as in Example 1 except that the basis weight of the card web was about 450 g / m ² and the distance between the steam nozzle and the suction side conveyor was 2.0 mm. The results are shown in Table 1.
Compared to the board of Example 1, this board shows the result of good bending evaluation despite the low density by securing the resin filling rate by increasing the basis weight instead of increasing the thickness. It was.

A board was obtained in the same manner as in Example 1 except that the basis weight of the card web was about 1400 g / m ² and the distance between the steam nozzle and the suction side conveyor was 6.0 mm. The results are shown in Table 1.
Although the board of Example 6 was thicker than the board of Example 5, it showed the result of the favorable bending evaluation similarly to Example 5 by increasing a fabric weight further.

A board of the present invention was obtained in the same manner as in Example 1 except that the distance between the steam nozzle and the suction side conveyor was 0.5 mm. The results are shown in Table 1.
Despite its thin thickness, high density ensures a high resin filling rate, ensuring good bending stress, especially high bending stress at 1.5 times displacement, and good bending evaluation results. It was.

Comparative Example 1
A web was prepared using 100% by mass of a core-sheath type composite fiber (3 dtex, 51 mm length) having a sheath component of a modified polyester having a melting point of about 140 ° C. by copolymerizing isophthalic acid and a core component of polyethylene terephthalate, Steam treatment was performed in the same manner as in Example 1 to obtain a board. The results are shown in Table 1.
The resulting board was in the shape of a board, but the adhesion between the fibers was not sufficiently developed, so the surface was not smooth enough, and this pocket was used when used as a partition material in the pocket part of the school bag. When the textbooks were repeatedly put in and out, the surface became fuzzy and could not be used for a long time.

Comparative Example 2
A board was obtained by calendering the web of Comparative Example 1 at 125 ° C. The results are shown in Table 1.
Although this board has a smooth surface compared to Comparative Example 1, the bending stress is 1.5 times lower because the resin filling rate in the center of the thickness is particularly low, and it is easy to break when bent. When it was used as a partition material for the pocket portion of the school bag, if the article was put in such a state that the pocket portion was pushed and spread, it was easily bent and bent.

Comparative Example 3
A board was obtained by calendering the web obtained in Example 1 in the same manner as in Comparative Example 2. The results are shown in Table 1.
Although this board has surface smoothness as in Comparative Example 2, the bending stress is 1.5 times lower because the resin filling rate is particularly low in the center of the thickness, and it is easily bent when bent. When it was used as a partition material for the pocket portion of the school bag, it was easy to produce eyes, and if the product was put in a state where the pocket portion was pushed and spread, it would be easily bent and bent.

A hot melt adhesive was applied to the surface of the board obtained in Example 1, and a polyester film having a thickness of 25 μm was laminated thereon to obtain a board. The results are shown in Table 1.
The board has become slightly heavier than the board of Example 1, but when used as a partition material for the inner pocket of a business bag, it is slippery due to the film. The sheet of paper on the surface was kept clean with no resistance.

  As is clear from the above results, the smooth and lightweight board of the present invention has a substantially uniform resin filling rate in the thickness direction while having a low density, and also ensures a high resin filling rate in the central region. It shows that it has excellent bending behavior, does not cause a sudden stress drop even if it exceeds the bending amount showing the maximum bending stress, and has excellent surface smoothness and lightness. .

Claims (7)

A board material mainly composed of a fiber nonwoven fabric containing 80 to 100% by mass of wet heat adhesive fibers, having a thickness of 0.5 to 6.0 mm and an apparent density of 0.2 to 0.7 g / cm ^3. A smooth and lightweight board material characterized by satisfying the following (1) to (3).
(1) Filling ratio of fiber resin in cross section is 40-80%
(2) On at least one surface, the average center line roughness is 100 μm or less. (3) The maximum bending stress in at least one direction is 1.0 N / 25 mm or more, and the bending amount is 1.5 times the maximum bending stress. It has a bending stress of 1/3 or more of the maximum bending stress. The smooth and lightweight board material according to claim 1, wherein the wet heat adhesive fiber is made of an ethylene-vinyl alcohol copolymer having an ethylene unit content of 10 to 60 mol%. The wet heat adhesive fiber is composed of an ethylene-vinyl alcohol copolymer having an ethylene unit content of 10 to 60 mol% and a fiber-forming polymer different from this, and the mass ratio of each component is The smooth light weight according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer occupies a part of the fiber surface continuously in the length direction. Board material. The wet heat adhesive fiber is a core-sheath type composite fiber, the sheath component is made of an ethylene-vinyl alcohol copolymer, the core component is made of a fiber-forming polymer, and the fiber-forming polymer is polyester. The smooth lightweight board | substrate material in any one of Claims 1-3. The smooth and lightweight board material according to any one of claims 1 to 4, wherein a filling ratio of the fiber resin in the central portion is 30 to 80% when the cross section is divided into three equal parts in the thickness direction. The smooth lightweight board material according to any one of claims 1 to 5, wherein a resin coat or a film is pasted on the surface. A fence partition material using the smooth and lightweight board material according to any one of claims 1 to 6.