JP4301398B2 - Stacked and integrated food absorbent mat - Google Patents

Description

  The present invention relates to a water absorbent mat for foods used as a rug in a dish when a fillet such as meat or fish is placed in a resin dish (tray) and packaged with a polymer film or the like.

  Conventional water-absorbing mats for food use are chemically bonded non-woven fabrics or dry pulp non-woven fabrics as water-absorbing bodies, all of which use acrylic or EVA resin emulsions as adhesives. . As a necessary characteristic of the water-absorbing mat, since strength in a wet state is required, N-methylacrylamide resin or the like is used as a cross-linking agent in a cross-linking step for developing the strength and water resistance of these resins. The occurrence could not be reduced to zero.

Conventionally, there is a literature relating to a food packaging material having air permeability and water absorption, in which through holes are opened with a large number of hot needles in a composite of a plastic film and pulp paper, etc., and both are integrated (for example, patent literature) 1, see Patent Document 2). Among these, in patent document 1, it is only described as "nonwoven fabric", and there is no description about the content.
On the other hand, in Patent Document 2, although an adhesive resin is not used, the drip absorbability of paper is not sufficient, and it is easy to tear after absorbing moisture generated from food, which causes a practical problem.
JP-A-62-109621 (Claims) Japanese Patent Publication No. 3-43053 (Claims)

  The problem to be solved is that the water absorbent mat for food using the conventional pulp paper has insufficient water absorption and strength, and the conventional chemical bond nonwoven fabric using a resin such as acrylic or EVA, or dry type Water-absorbing mats for foods in which pulp nonwoven fabrics are used as water-absorbing bodies require a crosslinking step in order to develop strength and water resistance, so generation of formalin is inevitable, and formalin generation is zero. That was not done.

The present invention relates to a two-layer laminated water-absorbing mat composed of a polyolefin film having an opaque surface on one side and an airlaid nonwoven fabric on the other side containing a thermoadhesive synthetic fiber, wherein the airlaid nonwoven fabric is thermally bonded. Synthetic fiber and pulp fiber are mixed in a ratio of 90/10 to 100/0% by weight, and the heat-adhesive synthetic fiber and / or the heat-adhesive synthetic fiber and the pulp fiber are thermally bonded. The surface layer part of both surfaces whose basis weight exceeds 5 g / m ² and is 12 g / m ² or less, the heat-adhesive synthetic fiber and the pulp fiber are mixed at a ratio of 60/40 to 85/15% by weight. And the inner layer portion having a weight per unit area of 8 to 60 g / m ² , and as a whole, between the surface layer portion and the inner layer portion, the thermoadhesive synthetic fibers Integrated by heat bonding The ratio of the vertical and horizontal tensile strength is 0.7 to 1.1 for both dry and wet conditions, and the ratio of tensile strength (vertical) for dry and wet conditions is 0.6 to 1.1, an airlaid nonwoven fabric with a layered structure integrated with a moisture absorption of 5 to 20 g / g and a total basis weight of 20 to 80 g / m ² , and with a hot needle, The present invention relates to a laminated and integrated water absorbent mat for foods, wherein the polyolefin film and the airlaid nonwoven fabric are melted, thermally bonded and laminated and integrated, and the film is also perforated.

The present invention demonstrates excellent performance by laminating a thermal bond type air laid nonwoven fabric to a polyolefin film, specifying the structure of the air laid nonwoven fabric, and using a hot needle to integrate and punch the film and the nonwoven fabric. A water-absorbing mat for food that can be provided can be provided. That is, no harmful volatile components such as formalin generated in the resin crosslinking step are generated, and a water-absorbing mat for food with high strength when wet can be provided, which is suitable as a drip sheet for food.

Embodiments of the present invention will be described below.
The airlaid nonwoven fabric integrated with the polyolefin film of the present invention has a three-layer structure comprising an inner layer composed of heat-adhesive synthetic fibers and pulp fibers, and a surface layer including the heat-adhesive synthetic fibers sandwiching the inner layer, It is integrated by bonding.
In the nonwoven fabric used in the present invention, the heat-adhesive synthetic fiber that is the main component forming the surface layer or mixed with the pulp may be any material that melts and bonds with each other. Well, the pulp is fixed with a network structure formed by the interfiber bonding, and fibers using a polymer having a high affinity with the pulp fibers are particularly preferable. Examples thereof include polyolefins, polyolefins grafted with unsaturated carboxylic acids, polyesters, polyvinyl alcohol, and the like.

  Among these, as the polyolefin-based heat-bonding synthetic fiber, a core-sheath type or an eccentric side-by-side type composite fiber is preferable. Examples of the polyolefin constituting the sheath or the outer periphery of the fiber include polyethylene and polypropylene. The polymer constituting the core component or the inner fiber layer is preferably a polymer having a melting point higher than that of the sheath and not changing at the heat bonding treatment temperature. Examples of such combinations include polyethylene / polypropylene, polyethylene / polyester, polypropylene / polyester, and the like. These polymers may be modified as long as they do not impair the action / effect of the present invention. Furthermore, it may be a fibrillar fiber. For example, SWP of Mitsui Chemicals, Inc. is mentioned.

  When the heat-adhesive synthetic fiber is thin, the number of constituent fibers increases, so that the number of fallen fibers decreases. When the heat-adhesive synthetic fiber is thick, the gap between the fibers increases and the bulky nonwoven fabric is obtained. The fineness is preferably 0.5 dt to 50 dt, more preferably 0.8 dt to 30 dt. If it exceeds 50 dt, the drop of the pulp cannot be suppressed, which is not preferable. On the other hand, if it is less than 0.5 dt, the productivity of the nonwoven fabric is lacking, which is not practical.

  The length of the heat-bonding synthetic fiber is preferably 1 to 15 mm. If the fibers are short, the mixability with the pulp is improved, and a more uniform non-woven fabric tends to be obtained. This is not preferable because the strength of the resin becomes low and the utility is lacking. On the other hand, if the length is longer than 15 mm, the strength of the nonwoven fabric increases, but the fibers tend to get entangled during pneumatic transportation of the fibers during the production of the nonwoven fabric, which increases the fiber lump defects, which is not preferable. Particularly preferred is 3 to 10 mm.

On the surface layer, in addition to the above heat-adhesive synthetic fibers, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, synthetic fibers such as polyester, polypropylene, polyamide and vinylon, and natural fibers such as pulp, cotton and hemp Other fibers may be included. In this case, the ratio of the heat-bonding synthetic fiber in the surface layer is 90 to 100% by weight . If the amount is less than 90% by weight, the above-mentioned other fibers may be more likely to drop off, and the effect of suppressing the pulp from dropping off from the inner layer may be reduced, and the wet strength may be lowered, causing a practical problem. .
These fibers forming the surface layer of the airlaid nonwoven fabric are heat-bonded, and the pulp is fixed by a network structure formed by bonding between the fibers. The basis weight must be more than 5 g / m ² and not more than 12 g / m ² . When the amount is 5 g / m ² or less, the amount of the synthetic fiber having water resistance and the number of bonding points between the fibers are small, so that not only a sufficient wet strength can be secured, but also adhesion failure occurs or the falling fibers tend to increase. On the other hand, if it exceeds 12 g / m ² , the water-resistant heat-bonding layer becomes too thick, moisture absorption into the inner layer becomes insufficient, and the cost becomes uneconomical.
As the basis weight increases, the strength increases but the water absorption decreases. However, within the scope of the present invention, it is possible to obtain a water-absorbing mat for foods that has sufficient water absorption, has strength even when wet, and does not lose fibers.

In the inner layer portion of the airlaid nonwoven fabric , the heat-bonding synthetic fiber and the pulp fiber are integrated by heat bonding. As the heat-adhesive synthetic fiber, the same one as the surface layer or a different one may be used. As the pulp fiber, a pulverized pulp having a length of 0.2 mm to 5 mm is preferable.
The mixing ratio of the thermoadhesive synthetic fiber and the pulp fiber in the inner layer portion is such that the thermoadhesive synthetic fiber / pulp fiber is 60/40 to 85/15% by weight . When the ratio of the pulp exceeds 40 % by weight, the strength becomes weak and delamination occurs, and the strength when wet is lowered. On the other hand, if it is less than 15 % by weight, the drip absorbability deteriorates.

  As the ratio of the heat-adhesive synthetic fiber increases, the strength increases but the water absorption decreases. Accordingly, it has been difficult to achieve both sufficient strength, particularly when wet, and water absorption. These compatibility is very important for a water absorbent mat for food. For the first time within the range of the ratio of the present invention, a water-absorbing mat for foods that maintains sufficient water absorption and has sufficient strength even when wet is obtained. Moreover, since the ratio of the heat-synthetic fiber is large, the bulk is small and it can be made thin.

In the inner layer, the heat-bonding synthetic fibers and the heat-bonding synthetic fibers and the pulp fibers are heat-bonded. The basis weight of this inner layer is 8 to 60 g / m ² . If it is less than 8 g / m ² , the amount of pulp is too small and water absorption is insufficient. On the other hand, if it exceeds 60 g / m ² , it is not suitable for this application because of excessive absorption. Preferably, it is 25-50 g / m < ² >, More preferably, it is 30-45 g / m < ² >.
In addition, the entire airlaid nonwoven fabric is also integrated between the front and back surfaces and the inner layer portion by heat bonding between the heat-bonding synthetic fibers. Furthermore, it has sufficient heat sealability.

Such an air laid nonwoven fabric is a nonwoven fabric produced by the air laid method. The nonwoven fabric produced by the airlaid method is preferred because the fibers forming the nonwoven fabric are randomly three-dimensionally oriented in the longitudinal direction, width direction and thickness direction of the nonwoven fabric.

Here, the nonwoven fabric by the airlaid method can be obtained as follows.
A fiber mainly composed of a predetermined amount of heat-bonded synthetic fiber that has been defibrated is conveyed while being uniformly dispersed in an air stream, and the fiber blown out from a screen having pores provided in a discharge part is installed at the lower part. The fiber is deposited on a net while dropping into a metal or plastic net and suctioning air at the bottom of the net. Next, a mixture of heat-adhesive synthetic fibers and pulp fibers is similarly deposited on the deposition sheet. Further, fibers mainly composed of heat-adhesive synthetic fibers are deposited on these sheets.
Then, the whole was heated to a temperature which the heat-adhesive synthetic fibers is sufficiently exert its adhesive effect can be obtained airlaid nonwoven fabric of the present invention. In order to fully exhibit the adhesive effect, heat treatment is required at a temperature 15 to 40 ° C. higher than the melting point of the adhesive component of the thermoadhesive synthetic fiber.

Thus, the nonwoven fabric manufactured by the airlaid method can three-dimensionally orient the fibers at random in the flow direction, width direction and thickness direction of the nonwoven fabric. And since these are thermally bonded, delamination does not occur. Moreover, since the non-woven fabric produced by the airlaid method has good uniformity, there is less variation in performance.
If necessary, further calendar processing and embossing processing can be performed.

In the air-laid nonwoven fabric used in the present invention, the ratio of vertical to horizontal strength is 0.7 to 1.1 when dried and wet, preferably 0.75 to 1.05, and more preferably 0.8. -1.0. If either one of the strengths is low, practical problems are likely to occur.
Moreover, the ratio of the tensile strength at the time of drying and wet is 0.6 to 1.1, preferably 0.7 to 1.1, and more preferably 0.8 to 1.1. Those less than 0.6 are non-woven fabrics whose strength when wet is greatly reduced compared to when dry, that is, weakened when wet, and deviates from the intention of the present invention, causing problems in practical use. Further, when wet, the strength increases due to the surface tension between fibers due to the presence of moisture and may exceed 1, which is also within the scope of the present invention, but unless there is another means of binding in the presence of any moisture. It is not normal to exceed 1.1.

The air laid nonwoven fabric used in the present invention needs to have an appropriate water absorbency, and the absorbency of water must be 5 to 20 g / g. Preferably it is 6-18 g / g, More preferably, it is 7-15 g / g. If it is less than 5 g / g, the absorbability is insufficient. On the other hand, if it exceeds 20 g / g, it can be said that it is practically excessive performance.

The basis weight of the entire air laid nonwoven fabric is 20 to 80 g / m ² . Preferably it is 40-70 g / m < ² >, More preferably, it is 50-60 g / m < ² >. If the amount is less than 20 g / m ² , the amount of water to be retained is insufficient. On the other hand, if the amount exceeds 80 g / m ² , the amount of water to be retained is excessive as a food absorbent mat.
In the present invention, the surface layer portions on both sides of the air laid nonwoven fabric are made of heat-adhesive synthetic fibers as described above, because the polyolefin film adhesion surface improves the adhesion when thermally bonded to the film, and the opposite surface. In order to prevent the occurrence of falling fibers.

Examples of the polyolefin film laminated and integrated with the airlaid nonwoven fabric as described above include a polyethylene film and a polypropylene film, and a polypropylene film excellent in rigidity is preferable.
Moreover, as such a polyolefin film , an opaque thing is used. As a means of opacification, a method of blending about 1 to 30% by weight of an inorganic filler such as titanium oxide or calcium carbonate, a method of blending a foaming agent into a film, and making it opaque by using a fine foam cell are applied. can do. By making the polyolefin film opaque, it is possible to conceal the blood paste of fish that migrate to the airlaid nonwoven fabric side. The thickness of the polyolefin film is preferably 15 to 40 μm, more preferably 25 to 35 μm. If it is less than 15 μm, the opacity is insufficient. On the other hand, if it exceeds 40 μm, the thickness of the film used for the water absorbent mat for food is excessive.

The water absorbent mat for food of the present invention is one in which the above polyolefin film and airlaid nonwoven fabric are laminated and integrated in a two-layer structure. These can be integrated with a hot needle. The polyolefin film and the heat-adhesive synthetic fibers in contact with the heat needle are melted and bonded to be integrated, but this heat needle not only heat-bonds but also simultaneously punches the film. Can do.
The punching and thermal bonding can be processed by passing the polyolefin film and the airlaid nonwoven fabric between the hot needle roll and the receiving roll. The temperature of the hot needle roll is preferably 180 to 350 ° C. If the temperature of the hot needle roll is less than 180 ° C., poor perforation or poor adhesion occurs. On the other hand, if it exceeds 350 ° C., it causes troubles such as being fused to the hot roll. More preferably, it is 250-330 degreeC.
The gap between the hot needle roll and the receiving roll is preferably 0.1 to 2 mm. If this distance is less than 0.1 mm, the bulk is crushed and the water retention performance is reduced. On the other hand, if it is more than 2 mm, it may cause poor hole formation or poor adhesion. Preferably it is 0.2-1.5 mm.

Further, in general, the melting hole is preferably circular in shape, the hole diameter φ is 0.1 to 2.0 mm, and the total opening ratio of all the melting holes in the mat area is preferably 3 to 30%. If the hole diameter of the melt hole is less than 0.1 mm, the water absorption is worsened. On the other hand, if it exceeds 2.0 mm, the appearance such as concealment is deteriorated. Further, if the open area ratio is less than 3%, the water absorption is insufficient, while if it exceeds 30%, the concealability is deteriorated and the appearance of the product is deteriorated.
The water absorbent mat for food of the present invention thus obtained is only thermally bonded, and is excellent not only in strength during drying but also in strength when wet. Also, the water absorption is good. Moreover, it does not crosslink to increase strength, and does not generate volatile components such as formalin by crosslinking.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not necessarily limited to these examples, and the present invention includes any design changes that do not depart from the spirit of the present invention. It is.

Example 1
Preparation of airlaid nonwoven fabric As heat-adhesive fibers for the front and back layers, a core-sheath type composite fiber (made by Teijin Fibers Ltd., F6, 2.2 dt, length 5 mm) having a core of polyethylene terephthalate and a sheath is pulp (Weyerhaeuser) Made of NB416 Kraft made by mixing 90% by weight and 10% by weight, respectively, and the inner layer part is a composite fiber having a core of polypropylene and a sheath of copolymer polyethylene (manufactured by Chisso Polypro Fiber Co., Ltd., Intac. 1 .7 dt, length 5 mm) and pulp (Weyerhaeuser, NB416 Kraft) mixed at 80 wt% and 20 wt%, respectively, and a heating temperature of 150 ° C. was used to produce a nonwoven fabric by the airlaid method.
The basis weight of the front and back layers was 11 g / m ² , and the basis weight of the inner layer was 38 g / m ² . The thickness was 0.89 mm.
Table 1 shows the vertical and horizontal strength, the ratio thereof, the ratio between dry and wet conditions, water absorption, and the like.
The tensile strength and water absorption were measured by the following methods.
(1) Tensile strength: According to JIS L-1913. However, the width of the test piece was 25 mm, and the holding interval was 100 mm.
(2) Water absorption (g / g, g / m ² ): On a glass plate tilted at 45 ° after a pre-weighed 100 mm × 100 mm test piece was immersed in water at 20 ° C. for 1 minute For 1 minute, then weigh again and divide the weight of the absorbed water by the weight of the specimen and display as g / g. Also, this is weighted and displayed as g / m ² .

Production of water-absorbing mat for food A water-absorbing mat 10 for food as shown in FIG. 1 was produced from the airlaid nonwoven fabric and polypropylene film (STC pearl film manufactured by SUTTONG) obtained as described above. This water absorbent mat for food is made by bonding a polypropylene film 11 and an airlaid nonwoven fabric 12 with a hot needle. The polypropylene film 11 and the air laid nonwoven fabric 12 are melted by a hot needle to open the melt hole 13, and at the same time, the polypropylene film 11 and the air laid nonwoven fabric 12 are thermally bonded by this melting.
Thermal bonding and punching with a hot needle were performed by passing the polypropylene film 11 and the airlaid nonwoven fabric 12 between a hot needle roll and a receiving roll. The temperature of the hot needle roll was 300 ° C., the gap between the hot needle roll and the receiving roll was 0.4 mm, and the processing speed was 20 m / min. Moreover, the shape of the molten holes is circular, the arrangement is staggered, the hole diameter is 0.6 mmφ, the pitch is 1.8 mm, and the open area ratio is about 17%.
The tensile strength and water absorption of the water absorbent mat for food obtained in this way were evaluated as described above. The evaluation results are shown in Table 1. Further, the obtained water absorbent mat for food did not have harmful volatile components such as formalin.

Comparative Example 1
In Comparative Example 1, the basis weight of the whole nonwoven fabric is 20 g / m ² without changing the structure and composition in Example 1. Since Comparative Example 1 has a small amount of water absorption, it is not suitable for use.

Comparative Example 2
In Comparative Example 2, only the pulp ratio of the inner layer part in Example 1 is changed to 80%. In Comparative Example 2, the wet strength is weak and the strength of the middle layer is particularly low.

  As shown in Table 1, the water absorbent mat for food of the present invention has a high strength even when wet and also has good water absorption.

  The water absorbent mat for foods of the present invention is excellent in strength and water absorbency, has no harmful volatile components such as formalin, and can provide a water absorbent mat suitable as a drip sheet for foods.

It is a perspective view of the water absorption mat for foods concerning the present invention. It is a principal part enlarged view of the water absorption mat for foods concerning this invention.

10 Water-absorbing mat for food 11 Polypropylene film 12 Airlaid nonwoven fabric 13 Melt hole

Claims (1)

A laminated water-absorbing mat having a two-layer structure comprising a polyolefin film with one side opaque and an airlaid non-woven fabric containing a thermoadhesive synthetic fiber on the other side, the airlaid non-woven fabric comprising a thermoadhesive synthetic fiber and The pulp fibers are mixed at a ratio of 90/10 to 100/0% by weight, and the heat-adhesive synthetic fibers and / or the heat-adhesive synthetic fibers and the pulp fibers are thermally bonded, The surface layer part of which both sides are more than 5 g / m ² and 12 g / m ² or less, the heat-adhesive synthetic fiber and the pulp fiber are mixed in a ratio of 60/40 to 85/15% by weight. And is composed of an inner layer portion having a basis weight of 8 to 60 g / m ² , and as a whole, between the surface layer portion and the inner layer portion is also thermally bonded between the heat-adhesive synthetic fibers. Integrated The ratio of the vertical and horizontal tensile strength is 0.7 to 1.1 for both dry and wet conditions, and the ratio of the tensile strength (vertical) for dry and wet conditions is 0.6 to 1.1. The polyolefin film is an airlaid nonwoven fabric with a layered structure integrated, having a moisture absorption of 5 to 20 g / g and a total basis weight of 20 to 80 g / m ² , and a heat needle. A laminate-integrated water absorbent mat for foods, wherein the air-laid nonwoven fabric is melted, thermally bonded and laminated to obtain a hole in the film.

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