JP3385105B2 - Manufacturing method of fruit packaging sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to fruits such as mandarin oranges,
The present invention relates to a method for producing a fruit packaging sheet used for, for example, shipping before being immature and fully ripening in the transportation process.

[0002]

2. Description of the Related Art When shipping fruits such as oranges for export, it takes a long period of time, for example, about 2 weeks, before they arrive at the export destination. The product is shipped in an immature state so as to be fully ripe under the condition of humidity of 80 to 90%), and when it arrives at the export destination, it can be sold in a fully ripe state.

To prevent the fruit from being damaged during this transportation,
Usually, unripe fruits are individually packaged before shipping and then packed in a cardboard case. The packaging sheet in this case needs air permeability and moisture permeability for the fruit to be fully ripe during the transportation process. Therefore, conventionally, Yankee paper of 18 to 20 g / m ² has been used as a packaging sheet.

[0004]

By the way, due to the recent shortage of manpower or rising labor cost, mechanization of fruit packaging is desired. As a mode of this mechanization, it can be considered that a fruit is packaged by a heat-sealing process, for example, a pillow type bag-making process using a bag-making machine.

In order to carry out this heat-sealing process, it is necessary to use a heat-sealable packaging sheet. Therefore, it is conceivable to use plastic sheets such as polyethylene, polypropylene, polyester, polyamide, vinyl chloride, vinylidene chloride, cellophane, and acetate that are suitable for heat-sealing, but since it has almost no air permeability and moisture permeability, it can be used for fruit packaging. Can not be used for.

It is possible to give air permeability and moisture permeability to these plastic sheets by subjecting them to punching or the like, but in this case, the moisture permeability becomes too high, and dew condensation occurs on the fruit, which may result in a long period of time. This will cause the fruits to rot during transportation.

On the other hand, it is desired that this type of packaging sheet has a paper-like appearance. This is because, for example, when fruits are exported overseas, particularly in the North American region, it is difficult to use non-woven fabric-like products that are difficult to decompose naturally in the soil because the North American region has a strong awareness of environmental protection. On the other hand, even in Japan, although there is not as high a consciousness as in North America, the motivation for environmental protection is increasing year by year
After all, products that look like paper are desired.

[0008] Therefore, the object of the present invention is to have air permeability and moisture permeability necessary for packaging fruits, and to make a bag by a heat sealing process, without peeling off the heat sealed portion during the transportation process. Another object of the present invention is to provide a method for producing a packaging sheet that can be easily peeled off by human power when opened and has a paper-like appearance.

[0009]

In order to solve the above-mentioned problems, the present invention provides a fruit packaging sheet for wrapping fruits and heat-sealing the opening for use in physical distribution, wherein a wood pulp having a freeness of 100 to 600 cc is used. relative to 75% by weight, the a heat-fusible composite fiber comprising a thermal adhesive low-melting resin and a high-melting resin 10 that was 25 wt% blended with fiber elements, the paper machine, the drying temperature The papermaking is performed at a temperature not lower than the melting point of the heat-meltable low-melting resin and lower than the melting point of the high-melting resin.

Preferably, the core-sheath type composite fiber in which the heat-meltable low-melting resin is the sheath and the high-melting resin is the core is the heat-meltable composite fiber.

More preferably, both the heat-fusible low-melting resin and the high-melting resin are polyester resins.

[0012]

As described above, as a fruit wrapping sheet, at least first, it should show appropriate air permeability and moisture permeability,
Second, the balance between the heat-sealing strength that does not peel during packaging and transportation and the heat-sealing strength that peels easily when taking out the fruit. What is shown is a condition.

By using the hot-melt non-woven fabric, it is possible to relatively easily obtain the one satisfying the first condition and the second condition. However, of course, it is not possible to obtain the third paper-like thing. Therefore, it is conceivable to mix the short synthetic fibers into the pulp fibers for papermaking.

However, depending on the amount of the short synthetic fiber added,
When dried with a Yankee dryer, the synthetic fibers are fused and deteriorate air permeability and moisture permeability.

However, according to the present invention, as the fiber to be mixed in the wood pulp, the heat-fusible composite fiber composed of the heat-fusible low-melting resin and the high-melting resin is used, and the melting point of the heat-fusible low-melting resin or higher is used. By drying at a temperature lower than the melting point of the high-melting point resin, the heat-melting low-melting point resin is relatively strongly bonded or entangled with the pulp fibers, and the air permeability and moisture permeability between the fibers are not impaired. be able to.

As the kind of the heat-fusible composite fiber in the present invention, polypropylene having a high melting point resin and polyethylene having a heat-fusible low melting point resin can be used. Since a certain amount of heat is applied, it is preferable that the heating temperature has a small difference from the melting point of the sheath portion, particularly a melting point of about 90 to 117 ° C., and the melting point of the core portion is 125 ° C. or higher.

Depending on the composite state of the composite fiber, there are core-sheath type (concentric type, eccentric type), side-by-side (parallel) type, block mixing type, split type, and the like.
In the present invention, any one may be used, but it is most preferable to use a core-sheath type composite fiber having a sheath portion made of a heat-meltable low melting point resin and a core portion made of a high melting point resin. The reason for this is that in the case of a core-sheath type composite fiber, after the heat-meltable low-melting resin is melted, the core remains circular and the periphery has a uniform adhesive property, so that strength can be obtained and it can be used for fruit packaging. This is because the optimum sheet can be obtained. An example of such a core-sheath type composite resin is "Kuraray Sofit N-720" manufactured by Kuraray Co., Ltd. The melting point of the sheath is 110 ° C. and the melting point of the core is 240 ° C.

On the contrary, the side-by-side type and the block-mixed type are not preferable because they have the same fiber diameter as before the melting even after the heat-fusible low-melting resin is melted, and the air permeability tends to be too high. .

Further, as the fineness of the composite fiber of the present invention,
0.7 to 2.0 d is preferable, and the fiber length is preferably 5 to 10 mm.

It is optimal to use NBKP as the wood pulp, but if it is within 50% of the total pulp, hardwood, hemp, bagasse, bamboo, kenaf, linters, mitsumata and kozo pulp are used. It can also be used together. The pulp freeness of wood pulp is set to 100 to 600 cc. If it is less than 100 cc, the drainage property is deteriorated and the paper-making property is deteriorated. On the contrary, if it exceeds 600 cc, the moisture permeability becomes too high, the dew condensation of the fruit occurs, and it becomes a cause of putrefaction and the air permeability. This is because the fruit cannot be sufficiently matured due to its height. For the same reason, the more preferable range is 200 cc to 400 cc.

The fiber content is 90% wood pulp.
Relative to 75% by weight, the core-sheath type heat fusible conjugate fiber 10
~ 25 % by weight. That is, if the content of wood pulp is less than 10% by weight, the air permeability and moisture permeability necessary for fruit ripening cannot be imparted. On the contrary, if it exceeds 90% by weight, the heat fusion force is It may become too small and the bag may tear during packaging or shipping.

[0022] Moreover, the amount of the pulp is less than 75%, the air permeability too high, variations in ripening occurs. This tendency is particularly noticeable when the fruits used for transportation are mandarin oranges. That is, the mandarin orange emits ethylene gas from the main body, and the maturation proceeds in a chain reaction by being stimulated by the ethylene gas. When the air permeability is too good, the generated ethylene gas is released outside the bag and the maturation does not proceed.
Therefore, in the present invention, the amount of wood pulp is 90 to 7
5% by weight and the compounding amount of the composite fiber was 10 to 25%
It is a thing.

If desired, additives commonly used in papermaking such as (acidic) sizing agents, wet paper strength enhancers, sulfuric acid bands, freshness-retaining agents (coconut husk activated carbon, zeocite, hinokiol, cristobalite powder) are added to the raw materials for papermaking if necessary. Further additions can be made.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples. Fibers composed of composite fibers or single fibers can be
15 kg / pT of an acidic sizing agent (AL120 days; manufactured by Japan PMC Co., Ltd.)
20 kg / pT of a wet paper strength agent (Kamen) and 50 kg / pT of a sulfuric acid band were added, papermaking was performed by a Yankee machine, and an experiment for producing a packaging sheet having a weight of 20 g / m ² of tsubo was performed.

At this time, although the composite fiber was mainly used as the fiber, the fineness, the fiber length, the composite form, the composite composition, and the blending ratio of the composite fiber and the wood pulp were appropriately changed. In addition, the pulp freeness of wood pulp and the dryer temperature during drying were also appropriately changed. In addition, of the core-sheath type composite fibers (concentric circle type) used as the composite fiber, the above-mentioned "SOFIT N-720" was used as the one in which the sheath portion and the core portion are made of polyester. In addition, “NBF (E)” was used as a material in which the core portion was polypropylene and the sheath portion was ethylene vinyl acetate. As an example of a parallel type composite fiber other than the core-sheath type, "SOFIT N-790"
Was used. Furthermore, as a single fiber, "Tepyrus TA
04 ”was used.

Each of the packaging sheets thus produced was processed into a pillow type bag, and the following measurements and evaluations were carried out.
As processing conditions, the center seal was 70 ° C., the end seal was 165 ° C., and a pressure of 6 kg / cm ² was used for 150 shots per minute.

In this experiment, the density and air permeability of the sheet were measured, and the appearance of the sheet was evaluated.
The heat-sealing strength was evaluated by the packaging evaluation, and the strength was evaluated by the transportation test.

Here, the evaluation of packing was carried out as follows.
Pack 4 to 5 mandarin oranges in one bag for bag making, and put 45 bags in one case by hand. 2
I put in one case every minute.

The transportation test was conducted as follows. The case in which the sheets were packed at the time of box evaluation was stored in a container for two weeks, and then the maturity of the oranges was evaluated. The conditions in the container were a temperature of 4 to 5 ° C and a humidity of 80 to 90%.

The suitability as a fruit packaging sheet was comprehensively evaluated by the above measurement items and evaluation items. Table 1 shows the experimental conditions and experimental results of each experimental example.

[0031]

[Table 1]

As can be seen from Table 1, the present invention is
It can be seen that it brings various excellent advantages.

[0033]

As is apparent from the above description, according to the present invention, it has air permeability and moisture permeability necessary for packaging fruits, and can be heat-sealed to make a bag, which is used in the transportation process. It is possible to obtain a packaging sheet that does not peel off the heat-sealed portion, can be easily peeled off by human power when opening, and has a paper-like appearance.

Continuation of front page (56) Reference JP-A-6-248595 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (3)

(57) [Claims] 1. A fruit wrapping sheet for wrapping fruits and heat-sealing the opening for use in distribution, comprising 90-90% wood pulp having a freeness of 100-600 cc.
A material in which 10 to 25 % by weight of the heat-fusible composite fiber composed of the heat-fusible low-melting point resin and the high-melting point resin is blended with 75 % by weight is used as a fiber element, and the drying temperature thereof is determined by a paper machine. A method for producing a fruit packaging sheet, which comprises performing papermaking at a temperature not lower than the melting point of the heat-meltable low-melting resin and lower than the melting point of the high-melting resin. 2. The fruit packaging sheet according to claim 1, wherein the core-sheath type composite fiber in which the heat-fusible low-melting resin is a sheath and the high-melting resin is a core is a heat-fusible composite fiber. Manufacturing method. 3. The heat-fusible low-melting point resin and the high-melting point resin are both polyester resins.
A method for producing a sheet for fruit packaging as described above.