JP2018161354A - Filter material for food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide while retaining conventional powder leakage property and heat sealability, a nonwoven fabric which is excellent in bag-making suitability of preventing slip-down from a conveyance arm in packaging and collapse in overlapping, caused by the low basis weight of a nonwoven fabric, aiming at improvement of an extraction speed, reduction of a cost, and improvement of beauty of exterior appearance such as transparency and glossiness during a general bag-making step of food filter application or the like.SOLUTION: A filter material for food has an average fiber diameter of a thermoplastic synthetic fiber constituting a nonwoven fabric of 10-30 μm, and a total basis weight of 10-50 g/m, and comprises a laminated nonwoven fabric whose flexural rigidity index obtained by following formula of [a flexural rigidity index {(gf cm)/(g/m)}×10={flexural rigidity (gf cm) with a KES flexural rigidity test machine/total basis weight (g/m)}×10] is 54-206.SELECTED DRAWING: Figure 1

Description

  The present invention is used in food filter materials, particularly for beverage extraction and soup extraction, and is a general product that occurs due to a decrease in flexural rigidity accompanying a reduction in weight per unit for the purpose of improving extraction speed and reducing costs. It is related with the filter material for foodstuffs which consists of a nonwoven fabric which eliminates the problem in a bag process.

  Conventionally, nonwoven fabrics of thermoplastic synthetic fibers have been widely used as filter materials for foods for extracting components of extraction materials such as green tea, black tea, barley tea, oolong tea, regular coffee, koji soup and koji soup. In recent years, nonwoven fabrics with a low basis weight tend to be required in order to improve the extractability of the extraction sheet, reduce costs, and improve the beauty of the appearance such as transparency and gloss.

  However, a commercial filter material made of a nonwoven fabric having a low basis weight is generally thin and has a low rigidity, so that it is difficult to handle in a general bag-making machine and has low mechanical suitability. For example, an extraction bag containing an extraction material such as tea leaves generally has a shape that bulges unevenly due to the extraction material when it is a pillow type. It is easy to become. In particular, in the case of an extraction bag made of a non-woven fabric with a low basis weight, this becomes more prominent, and there is a problem that the handleability is low due to slippage from the transport arm during packing or collapse during stacking.

  On the other hand, generally an extraction sheet made of paper has high bending rigidity even at a low basis weight, and the shape retaining property of the extraction bag becomes high, so that it is easy to handle when manufacturing an extraction bag or the like. However, paper is low in transparency and extraction speed is slow. Furthermore, there is a problem that the bitter component derived from paper is eluted at the time of extraction, and the flavor is impaired. These points are disadvantages of using paper as an extraction bag.

The following Patent Document 1 discloses a filter material for food that has less powder leakage and is excellent in heat sealability, component extractability, bending rigidity, and the like, and a method for producing a food-filled tare using the same as a non-woven fabric. . However, the bending rigidity with respect to the fabric weight is small, and when the fabric weight is lowered for the purpose of improving the extractability and reducing the cost, in particular, when the fabric weight is 15 g / m ² or less, the bag-making suitability is not sufficiently satisfied.

  In addition, Patent Document 2 below uses a property that a crease is easily formed by lowering the crystallinity of a melt-blown nonwoven fabric made of polylactic acid resin fibers, and makes a crease line or bends. In addition, it is disclosed that a tight and straight state is provided to improve the shape retention of the extraction bag. However, melt-blown fibers having low crystallinity have a broad melting peak on the low melting point side, and the resin tends to adhere to the heat seal bar during heat sealing in a general bag making process. In particular, PLA resin has a very high heat decomposability compared to PP resin and PET resin, and the quality is reduced due to degradation products adhering to the extraction bag, and it is necessary to wipe off the dirt at regular intervals. It also leads to a decline.

  Furthermore, the following Patent Document 3 discloses a spunbonded nonwoven fabric specializing in a parameter called bending rigidity and having an excellent texture. However, only the technical idea of reducing the bending rigidity in order to ensure the texture is disclosed.

JP 2008-54840 A International Publication No. 2016/147978 JP 2014-141752 A

  In view of the above-described problems of the prior art, the problem to be solved by the present invention is to improve the extraction speed and reduce the cost in a general bag making process such as food filter use, and further, the appearance such as transparency and gloss. Non-woven fabrics with excellent bag-making properties that do not cause slippage from the transfer arm during packing or collapse during stacking due to the low weight of nonwoven fabrics for the purpose of improving the beauty of the fabric. It is to provide while maintaining.

As a result of intensive studies to solve the above problems, the present inventors have devised a heat bonding method using an embossing roll, increasing the number of yarn-thread bonding points at non-embossed portions, and further maintaining the thickness of the nonwoven fabric. The present inventors have found that the bending rigidity is dramatically improved and have completed the present invention.
That is, the present invention is as follows.

[1] The average fiber diameter of the thermoplastic synthetic fibers constituting the nonwoven fabric is 10 to 30 μm, the total basis weight is 10 to 50 g / m ² , and the following formula:
Bending stiffness index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ⁶ = {Bending stiffness (gf · cm) / total basis weight (g / m ² ) by KES bending stiffness tester ^2.5 } × 10 ⁶
A food filter material comprising a laminated nonwoven fabric, wherein the flexural rigidity index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ^{6 determined} by the formula ( ¹ ) is 54 to 206.
[2] The food filter material according to [1], wherein the number of adhesion points between yarns from the embossed end of the laminated nonwoven fabric to a point of 0.3 mm is 10 or more.
[3] The food filter material according to [1] or [2], wherein the thickness of the laminated nonwoven fabric is 0.06 mm or more.
[4] The food filter material according to any one of [1] to [3], wherein the laminated nonwoven fabric has a crystallinity of 30% or more.
[5] The laminated nonwoven fabric is composed of a plurality of layers, at least one of the plurality of layers is a nonwoven fabric layer composed of fibers of thermoplastic synthetic resin, and the other layer is the at least one layer. The food filter material according to any one of [1] to [4], wherein the filter material is a nonwoven fabric layer composed of fibers of a thermoplastic synthetic resin having a melting point lower by 30 ° C to 150 ° C than the melting point of the thermoplastic rigid resin. .
[6] The food filter material according to any one of [1] to [5], wherein the seal strength is 2 to 50 N / 25 mm.

  The filter material for foods comprising the laminated nonwoven fabric of the present invention is a low-weight nonwoven fabric for the purpose of improving the extraction rate and lowering the weight for the purpose of cost reduction, and further improving the appearance of the appearance such as transparency and gloss. In weighting, the conventional food filter non-woven fabric retains powder leakage and heat sealability, and eliminates slipping from the transport arm during packing and collapse during stacking.

It is a graph which shows the relationship between bending rigidity index {(gf * cm) / (g / m < ² >) ^2.5 } * 10 < ⁶ > and a fabric weight. It is a graph which shows the relationship between the bending rigidity (gf * cm) in 15 g / m < ² > of fabric weight, and thickness (mm). It is a SEM photograph which shows that there are many adhesion points of thread | yarns. It is a SEM photograph which shows that there is no number of adhesion points of yarns.

Hereinafter, embodiments of the present invention will be described in detail.
The filter material for food of this embodiment has an average fiber diameter of 10 to 30 μm, a total basis weight of 10 to 30 g / m ² , and the following formula:
Bending stiffness index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ⁶ = {Bending stiffness (gf · cm) / total basis weight (g / m ² ) by KES bending stiffness tester ^2.5 } × 10 ⁶
Is a food filter material comprising a laminated nonwoven fabric, wherein the flexural rigidity index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ^{6 determined} by the formula ( ¹ ) is 54 to 206.
In the laminated nonwoven fabric, for example, the first layer is a thermoplastic fiber (S) having a high melting point, the second layer is a resin constituting the first layer, the core side, and a resin having a melting point lower by 30 ° C. or more than the melting point of the resin is the sheath side. A laminated nonwoven fabric having an S / W structure in which the thermoplastic sheath-core rigid fibers (W) are laminated and integrated by thermocompression bonding.
In particular, in the second-layer sheath-core fiber ultra-fine fiber (W), by providing a difference in melting point between the first layer and the second layer, the bonding between the layers can be strengthened by thermocompression bonding, and the heat seal strength and temperature range are wide. Features such as can be obtained.

  The laminated nonwoven fabric may be obtained by laminating ultrafine fibers between these layers for the purpose of improving powder leakage between the first layer and the second layer.

  The high-melting thermoplastic synthetic fiber layer of the first layer is usually composed of thick fibers having a fiber diameter of 10 to 30 μm, preferably 12 to 20 μm, and is preferably excellent in strength and breathability and has high wear strength. Examples of such constituent fibers include synthetic fibers such as polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, and copolyester, and polyamide fibers such as nylon 6, nylon 66, and copolyamide fibers.

  The thermoplastic synthetic fiber layer of the second layer is made of fibers having a melting point lower than that of the fibers of the first layer by 30 ° C. or more, preferably 50 ° C. or more, and serves as a heat seal surface of the bag structure. A thick fiber having a fiber diameter of 10 to 30 μm, preferably 12 to 20 μm is preferable. Examples of the constituent fiber include olefin fibers such as low density polyethylene, high density polyethylene, polypropylene, copolymer polyethylene, copolymer polypropylene, polyethylene terephthalate, phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol, 1,4 -Synthetic fibers such as aromatic polyester copolymers obtained by copolymerizing one or more butanediol compounds, polyester fibers such as aliphatic polyesters, and copolymerized polyamide fibers are used. Furthermore, a composite fiber composed of two components such as a core-sheath structure and side-by-side, for example, a composite fiber having a high melting point in the core and a low melting point in the sheath, specifically, the core is polyethylene terephthalate, polybutylene terephthalate, copolymer polyester, High melting point fibers such as nylon 6, nylon 66, copolymerized polyamide, and the like, and low melting point fibers such as low density polyethylene, high density polyethylene, polypropylene, copolymerized polyethylene, copolymerized polypropylene, copolymerized polyester, and aliphatic polyester as the sheath are preferable.

  Although the manufacturing method of a laminated nonwoven fabric is not specifically limited, Preferably a 1st layer and a 2nd layer can be a spunbond method, and an ultrafine fiber layer can be a meltblown method.

  The crystallinity of the laminated nonwoven fabric is 30% or more, preferably 35% or more. When the degree of crystallinity is less than 30%, thermal shrinkage at the time of heat sealing increases, leading to powder leakage and poor quality due to poor sealing. Moreover, it has a broad melting peak on the low temperature side, and the resin tends to adhere to the heat seal bar during heat sealing in the bag making process. As a result, the pyrolyzate adheres to the extraction bag, leading to a reduction in quality.

  The fiber diameter of the ultrafine fiber is preferably 7 μm or less, more preferably 1 to 5 μm, and serves to reduce the fiber gap and the maximum opening diameter, thereby reducing powder leakage. In particular, by laminating the fine fiber gaps so that the fine fibers are covered, the fiber gaps can be reduced with a small fine fiber ratio. When the fiber diameter exceeds 7 μm, the effect of covering the fiber gap decreases.

Basis weight of the microfibers, 1 g / ^{m 2} or more, more preferably 1.5~10g / ^{m 2,} more preferably from 2~7g / ^{m 2.} When the basis weight of the ultrafine fiber is less than 1 g / m ² , the dispersibility of the ultrafine fiber layer becomes insufficient.

  The crystallinity of the ultrafine fibers is preferably 10% or more, more preferably 20% or more, and further preferably 30% or more. When the crystallinity is less than 10%, the melting point has a broad melting peak on the low temperature side, the resin adheres to the seal bar during heat sealing in the bag making process, and the thermal decomposition product adheres to the extraction bag. This leads to a decline in quality.

  The content ratio of the ultrafine fibers with respect to the entire laminated nonwoven fabric is usually 5 to 50 wt%, preferably 7 to 30 wt%. Examples of the ultrafine fibers include polyolefin fibers such as polyethylene and polypropylene, polyamide fibers such as nylon 6 and nylon 66, polyethylene terephthalate, polybutylene terephthalate, copolymerized polyester, and aliphatic polyester.

  The laminated nonwoven fabric has a melting point difference between the fibers of the first layer and the second layer, but the melting point of the fibers constituting the second layer is preferably 30 ° C. or higher, more preferably in the range of 50 to 150 ° C. The temperature is preferably lower than the melting point of the fibers constituting the first layer. The roll temperature range at the time of partial thermocompression bonding can be set wide due to such a melting point difference. When the difference between the upper and lower sides of the thermocompression-bonding roll temperature exceeds 150 ° C., the low-melting fiber tends to deteriorate due to the influence of the roll temperature on the high melting point side. On the other hand, when the melting point difference between the first layer and the second layer is less than 30 ° C., the thermocompression bonding temperature range becomes narrow, and the strength and the friction fluff strength are easily affected by the roll temperature conditions.

  The integration of the laminated nonwoven fabric by thermocompression bonding means, for example, heating and pressure bonding between a known embossing roll and a smooth roll to join them. The heating temperature is in the temperature range from the temperature above the softening temperature of the fiber to the melting point. However, in consideration of thermal degradation of the low melting point fiber, the temperature difference between the upper and lower rolls is preferably 150 ° C. or less, and more preferably 130 ° C. or less. The pressure for thermocompression bonding is preferably 10 to 1000 kPa / cm, more preferably 50 to 700 kPa / cm.

In the laminated nonwoven fabric constituting the food filter material of the present embodiment, by controlling the pattern, pitch, repeat, depth, and adhesion area ratio of the embossing roll, the yarns within 0.3 mm from the embossed end can be bonded to each other. By increasing the number of points and maintaining the thickness, as shown in FIG. 1, the bending stiffness per unit weight, that is, the value of the bending stiffness index (cm ⁻¹ ) is improved by one step as compared with the conventional nonwoven fabric. ing. Specifically, the number of adhesion points between yarns is increased by decreasing the pitch and repeat, and the thickness is maintained by increasing the depth, thereby greatly improving the bending rigidity.

  In the laminated nonwoven fabric, the number of adhesion points between yarns within 0.3 mm from the embossed end is preferably 10 or more, more preferably 15 or more. If it is 10 or less, the effect of improving the bending rigidity is reduced. In addition, the adhesion | attachment point of thread | yarns is the location enclosed in FIG. FIG. 3 shows an example in which the number of adhesion points is large, and FIG. 4 shows an example in which there is no number of adhesion points.

  The thickness of the laminated nonwoven fabric is preferably 0.06 mm or more, more preferably 0.07 mm or more. When the thickness is 0.06 mm or less, the effect of improving the bending rigidity is reduced.

  KES flexural rigidity (quasi-bending test air KES FB2-AUTOA) is a characteristic necessary to maintain the shape during transportation, storage, and extraction when the bag is made into a bag such as a Tetra Pak containing the extract. . The KES bending rigidity of the food filter material of the present embodiment is preferably 0.03 to 0.5 (gf · cm), more preferably 0.045 to 0.22 (gf · cm), and still more preferably. Is 0.065 to 0.22 (gf · cm). If the KES bending rigidity is less than 0.03 (gf · cm), the rigidity is low, and the workability deteriorates during bag making. On the other hand, the side with high bending rigidity has good bag-making processability and shape retention, and if it is 0.5 (gf · cm) or less, it will swell due to hot water of the extractable when used in food bags. , Problems such as restraining expansion do not occur.

In the laminated nonwoven fabric constituting the food filter material of the present embodiment, the following formula:
Bending stiffness index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ⁶ = {Bending stiffness (gf · cm) / total basis weight (g / m ² ) by KES bending stiffness tester ^2.5 } × 10 ⁶
The flexural rigidity index determined by is from 54 to 206, preferably from 66 to 206, more preferably from 66 to 150.

  The above-mentioned KES bending stiffness and bending stiffness index can be achieved by increasing the basis weight or increasing the embossed area ratio. However, in these methods, the air permeability and the aperture diameter are made smaller than necessary. This leads to a decrease in extraction speed and transparency. In the food filter material of this embodiment, by controlling factors that do not affect the extraction speed, such as the number of adhesion points and thickness between yarns, the bending rigidity and the pore diameter, that is, the bending rigidity without changing the extraction speed and transparency are maintained. It aims to improve.

In the food filter material of this embodiment, the number of adhesive points between yarns is increased and the thickness is maintained to dramatically improve the bending rigidity. Especially, it is necessary for bag making even with a light weight of 15 g / m ² or less. Can ensure high bending rigidity.

The air permeability of the food filter material of the present embodiment is preferably 50 to 700 cm ³ / cm ² / s, more preferably 200 to 600 cm ³ / cm ² / s, and even more preferably 300 to 600 cm ³ / cm ² / s. It is. If it exceeds 700 cm ³ / cm ² / s, the extraction speed is improved, but powder leakage is liable to occur, and the seal strength, rigidity, etc. are reduced. On the other hand, if it is less than 50 cm ³ / cm ² / s, powder leakage is difficult, seal strength and rigidity increase, and component extractability decreases.

  The pore diameter of the food filter material of the present embodiment is preferably 60 to 200 μm, more preferably 100 to 200 μm, and still more preferably 140 to 200 μm. If it exceeds 200 μm, powder leakage is liable to occur, and the sealing strength, rigidity, etc. decrease. On the other hand, if it is less than 60 μm, it is difficult for powder to leak, seal strength and rigidity increase, and component extractability decreases.

  In the production of laminated nonwoven fabrics, the angle formed with the roll surface of the embossed roll pin is characterized by the fact that the greater the number of adhesion points between the yarns, the greater the durability, depending on the distance to the adjacent embossed pitch. The optimum angle may be selected according to the repeat and adhesion area ratio.

The embossing roll pattern may be a texture pattern, a silk pattern, a turtle shell pattern, or a point pattern, and is not particularly limited.
You may use the clearance roll which can maintain thickness more by providing a gap between rolls at the time of thermocompression bonding. In addition to using an embossing roll, an air-through method in which hot air is passed through the web and the yarns are heat-bonded may be performed as post-processing.

  The bag making process using the food filter material of the present embodiment is performed by stacking with the second layer of the filter material on the inside, and sealing the end portion as a seal by a known sealing method. Done. For example, it can be performed by a heat sealing method such as a three-pack sealing machine or a four-pack sealing machine, or an ultrasonic sealing method such as an ultrasonic sealing machine. Furthermore, it is possible to form a bag into two or more continuous continuous bags.

  For example, the bag body needs to have a high sealing strength because the filling material filled in the bag does not drop or breaks when a heavy material is loaded. Therefore, the sealing strength of the bag body is 1 N / 25 mm or more, preferably 1.5 N / 25 mm or more, more preferably 2 to 50 N / 25 mm. When the seal strength is less than 1 N / 25 mm, the seal portion is easily peeled off, causing problems such as leakage of contents to the outside.

  In order to carry out the bag making process stably, it is necessary that the sealing temperature range is wide. For example, the temperature range is preferably 50 ° C. or higher and 150 ° C. or lower. This is because it is difficult to control the temperature of the sealing portion of the sealing machine to a constant temperature, for example, the temperature gradually increases from the start and further changes depending on the environmental temperature. When the temperature range needs to be set in a narrow range of less than 50 ° C., there arises a problem that the seal strength changes due to the influence of the environmental temperature, the heat storage of the heater portion, and the like. On the other hand, in a temperature range exceeding 150 ° C., physical properties are reduced due to thermal deterioration of the low melting point fiber.

  In the food filter material of this embodiment, a wide sealing temperature range can be obtained, and a high and stable sealing strength can be obtained. This is because, for example, a difference in melting point of 30 ° C. or more is provided between the fibers of the first layer and the second layer, so even if the fibers of the low melting point layer soften or melt, the high melting point fibers have a predetermined fiber shape. This is because it is maintained. Accordingly, the fiber melt does not adhere to the heat seal bar during bag making.

  In the filter material for food of the present embodiment, even when the laminated nonwoven fabric is a laminated sheet containing ultrafine fibers, the crystallinity is high and the melting point does not broaden to the low melting point. Things do not stick.

The food filter material and the bag of the present embodiment have high sealing strength, and are excellent in rigidity and component extractability. The total basis weight of the laminated nonwoven fabric is 10 to 30 g / m ² , preferably 10 to 20 g / m ² , more preferably 10 to 16 g / m ² . When the total basis weight is less than 10 g / m ² , powder leakage is likely to occur, and the seal strength, rigidity, and the like are reduced. On the other hand, when the total basis weight exceeds 30 g / m ² , powder leakage becomes difficult, seal strength and rigidity increase, and component extractability decreases.

  The extract to be filled in the bag body is not particularly limited as long as it is a solid substance such as a powder shape or a granular sheet. For example, tea leaves such as green tea, oolong tea, barley tea, black tea, etc. for taste drinks, regular coffee fine ground, medium fine ground, coarse ground powder, etc. Such mixed powders.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. The measurement method and evaluation method used were as follows.

(1) Weight per unit area (g / m ² )
A sample of 20 cm in length and 25 cm in width is cut out at three places, the weight is measured, and the average value is calculated by converting it into mass per unit. (JIS-L-1906)

(2) Average fiber diameter (μm)
Take a 500 times magnified photograph with a microscope and obtain the average value of 10 pieces.

(3) KES bending rigidity (gf · cm): As a measuring device, KES · FB2-AUTO-A manufactured by Kato Tech Co., Ltd. is used. The sample is 20 cm × 20 cm and the KES bending stiffness is measured.

(4) Number of adhesion points between yarns A sample is observed with a microscope, and the number of fusion points between yarns from the embossed end to the 0.3 mm point is counted. Three embosses are selected at random for each sample, and the average value of N = 3 is defined as the number of adhesion points between the yarns of the sample. The magnification may be selected appropriately, but in the present invention, it is 350 times that makes it easy to determine the fusion between the yarns. The number of adhesion points is counted. 3 and 4 are taken from the front, but if it is difficult to see the fusion between the yarns, they may be taken slightly tilted.

(5) Air permeability (cm ³ / cm ² / s)
Conforms to JIS-L-1906 Fraule Law.

(6) Opening diameter (μm)
Take a 100x magnified photograph of the platinum-deposited sample with a microscope, calculate the area of the voids seen by binarizing the captured image, and calculate the equivalent circle when the area is 2.3% of the total area Is calculated.

(7) Thickness (mm)
Measure thickness at 100 g load using a thickness gauge manufactured by Mitsutoyo.

(8) Crystallinity (%)
Measurement is performed with a differential scanning calorimeter (DSC6000, manufactured by PerkinElmer). Measurement program: 1) Incubate at 30 ° C for 1 minute, 2) Increase to 300 ° C at 10 ° C / min. The amount of heat in the cold crystal part and the melted part is calculated, and the crystallinity is obtained by the following equation.
Amount of crystals = calorie of melting part (J / g)-calorie of cold crystal part (J / g)
Crystallinity (%) = Crystal content (J / g) /126.4×100

(9) Seal strength (N)
Using a constant-length tensile tester, cut a sample width of 25 mm and a length of 200 mm, peel off the heat seal part about 50 mm in the vertical direction, and attach each piece so as to peel 180 °. The peel strength was measured at three points each for length and width, and the average value of the maximum strengths is shown. However, the seal temperature is 120 ° C., the time is 1 second, the pressure is 5500 kPa, and the seal area is 7 mm × 25 mm.

[Examples 1-7]
As a second layer, a composite fiber web having an average fiber total of 14 μm in a core-sheath structure in which a core is polyethylene terephthalate and a sheath is an aromatic polyester copolymer (melting point 210 ° C.) is formed from a two-component spinneret for spunbond, On top of that, as a first layer, a general polyethylene terephthalate is spun from a spinneret for spunbond, a thermoplastic fiber web having an average diameter of 14 μm at a spinning temperature of 300 ° C. is laminated as a laminated fiber web on the collection net, and the total weight is obtained. Adjusting the conveyance speed to 15g / m ² , thermocompression bonding with an embossing pattern of any embossed pattern, bonding area ratio, pitch, repeat, depth, up and down temperature of 210 ° C / 110 ° C, linear pressure of 350N / cm And the filter material for foodstuffs of Examples 1-7 was obtained.

  The characteristics of the obtained filter material are shown in Table 1 below. From the result of Table 1, the filter material for foodstuffs of Examples 1 to 7 with respect to the nonwoven fabric of the comparative example is from the embossed end to the 0.3 mm point while maintaining the air permeability, the powder leakage rate, and the seal strength. It can be seen that the number of adhesion points between the yarns is increased, and the filter material has excellent bending rigidity. On the other hand, when the depth of the embossing roll is made too small as in Examples 5-7, which are the same weight, the thickness decreases and the number of bonding points between the yarns increases, but the effect of improving the bending rigidity is slightly low. It has become. That is, as shown in FIG. 2, the bending rigidity improvement effect by increasing the number of adhesion points between yarns and the bending rigidity improvement effect by maintaining the thickness are combined, and the bending rigidity is dramatically improved.

[Examples 8 and 9]
The foods of Examples 8 and 9 were prepared by changing the conveyance speed so that the basis weight was 10 and ²⁰ g / m ^{2 in} the fiber configuration of Example 1, and thermocompression bonding with the embossing roll of Example 3 under the same temperature conditions. A filter material was obtained.

  The characteristics of the obtained filter material for food are shown in Table 1 below. From the results of Table 1 below, the food filter material of the present embodiment has an increased number of bonding points between yarns from the embossed end to the 0.3 mm point for both the low weight and the high weight, and further maintains the thickness. Thus, it can be seen that the effect of improving the bending rigidity is obtained.

[Examples 10 and 11]
Examples 10 and 11 were prepared by embossing rolls having different embossed patterns, bonding area ratios, pitches, repeats, and depths in the fiber configuration of Example 1 at a vertical temperature of 210 ° C./110° C. and a linear pressure of 350 N / cm. A filter material for food was obtained.

[Example 12]
20 wt% of the total weight of polyethylene terephthalate having an average fiber diameter of 2 μm by the melt blown method was inserted between the fiber layers of Example 1, and the conveyance speed was adjusted so that the basis weight was 15 g / m ^2. The food filter material of Example 12 was obtained by thermocompression bonding under the same temperature conditions.

  The characteristics of the food filter material obtained in Examples 10 to 12 are shown in Table 1 below. From the results shown in Table 1, the filter material for food according to the present embodiment is a yarn from the embossed end to the 0.3 mm point by appropriately selecting the embossed pitch, repeat, and depth even if the embossed roll pattern is changed. It can be seen that the number of adhesion points between each other increased and the thickness was also maintained, and an effect of improving the bending rigidity was obtained.

[Comparative Examples 1-7]
The conveyance speed was changed so that various fabric weights were obtained in the fiber configuration of Example 1, the embossed pattern was a textured pattern, the bonding surface seating ratio was 14.4%, the pitch was 2 mm, the repeat mm, and the depth was 0.32 mm. The filter material for foodstuffs of Comparative Examples 1-7 was obtained by thermocompression bonding at a temperature of 210 ° C / 110 ° C and a linear pressure of 350 N / cm.

[Comparative Example 8]
The conveyance speed was adjusted so that the basis weight was 15 g / m ^{2 in} the fiber configuration of Example 12, and thermocompression bonding was performed under the same embossing conditions as in Comparative Examples 1 to 7 to obtain a food filter material for Comparative Example 8.

  The characteristics of the food filter materials obtained in Comparative Examples 1 to 8 are shown in Table 2 below. From the results shown in Table 2, the obtained filter material has a small number of yarn-thread adhesion points, and has a low bending stiffness per unit weight (that is, a bending stiffness index).

The food filter material of the present invention is excellent in powder leakage, heat seal processability, seal strength, bending rigidity, etc., and can therefore be used in a wide range of applications as a packaging material for an extractable substance such as powder and granular materials. . For example, it can be suitably used as a filter material for extracting components for taste drinks and for soup stock.
In particular, even if the basis weight is low, the rigidity is high and the bag making is excellent, making it possible to improve the extractability of the extraction sheet, reduce the cost, and lower the basis weight to improve the beauty of the appearance such as transparency and gloss. It is suitable for.

Claims (6)

The average fiber diameter of the thermoplastic synthetic fiber constituting the nonwoven fabric is 10 to 30 μm, the total basis weight is 10 to 50 g / m ² , and the following formula:
Bending stiffness index {(gf · cm) / (g / m ² ) ^2.5 } × 10 ⁶ = {Bending stiffness (gf · cm) / total basis weight (g / m ² ) by KES bending stiffness tester ^2.5 } × 10 ⁶
The foodstuff filter material which consists of a laminated nonwoven fabric characterized by the bending rigidity index calculated | required by 54-206 being characterized by the above-mentioned.   The filter material for food according to claim 1, wherein the number of adhesion points between yarns from the embossed end of the laminated nonwoven fabric to a point of 0.3 mm is 10 or more.   The filter material for foodstuffs of Claim 1 or 2 whose thickness of the said laminated nonwoven fabric is 0.06 mm or more.   The filter material for foodstuffs of any one of Claims 1-3 whose crystallinity degree of the said laminated nonwoven fabric is 30% or more.   The laminated nonwoven fabric is composed of a plurality of layers, at least one of the plurality of layers is a nonwoven fabric layer composed of thermoplastic synthetic resin fibers, and the other layer is the at least one thermoplastic layer. The filter material for foodstuffs of any one of Claims 1-4 which is a nonwoven fabric layer comprised from the fiber of a thermoplastic synthetic resin which has 30 to 150 degreeC melting | fusing point lower than melting | fusing point of rigid resin.   The food filter material according to any one of claims 1 to 5, wherein the seal strength is 2 to 50 N / 25 mm.