JPH0819639B2 - Freshness maintaining paper and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a water-absorbent paper having absorptive and absorbing properties, and in particular, vegetables and other fresh foods and frozen foods that adhere water to the surface or emit water vapor. The present invention relates to a water-absorbent freshness-maintaining paper used for transporting products and the like.

(Prior art) Traditionally, vegetables are packed in a cardboard box for transportation immediately after harvesting with a lotus, or washed with soil and bundled in a fixed amount and packed in a cardboard box. In order to make it possible, newspapers etc. are packed between vegetables and transported,
In addition, vegetables, flowers and fruits are sometimes transported by putting a bag containing ice etc. in the packaging box to maintain freshness, but newspapers etc. are laid in the packaging box to absorb the generated water droplets. I came.

However, recently, the solid content of acrylic resin etc. is 10
A highly water-absorbent resin that absorbs 0 to 1000 times the amount of water has been developed, and a sheet sandwiched with granular particles of these resins with water-permeable paper or non-woven fabric is used as an underlay that absorbs water for transportation such as cardboard boxes. It has come to be used for boxes.

(Problems to be Solved by the Invention) As described above, when transporting vegetables, flowers, fruits, etc., particularly those that are cultivated in the stalk and packed in the cardboard box immediately after harvesting have good water resistance in the cardboard box itself. Although water drops are attached to the inner surface of the box due to that, the water may reattach to vegetables etc. and the part may rot and be damaged. , I wrapped vegetables directly, but the paper got wet and broke, and it took a lot of time to remove these papers when opening, and the contents could be damaged.

Recently, the developed high-quality water-based resin has come to be used by being sandwiched between papers, but it is difficult to handle because it is held by a soft water-absorbent paper, and it also holds fine powder of super-water-absorbent resin. For emphasizing, paper and paper are joined by embossing, etc. Furthermore, since water-absorbent paper easily breaks when absorbing water, wrap the outside with water-permeable and strong non-woven fabric even if wet with water, etc. Therefore, it does not become expensive, how cheap and easy it is to handle, it has good water absorption, and the absorbed water does not reattach to the package and does not break. The development of paper has become desired.

(Means for Solving the Problem) The present invention is particularly harvested in a state where many water droplets are attached,
As a result of various studies aimed at obtaining a highly water-absorbing freshness-keeping paper used for insole of fresh vegetables packed in a cardboard box and transported, the present applicant invented it in June 1988. What can be solved by further improving the applied water-absorbent sheet, that is, a highly water-absorbent resin, for example, vinyl acrylate vinyl copolymer, fine spherical particles or powder of synthetic resin polymer such as sodium acrylate polymer However, thermoplastic resins such as polyethylene and polypropylene are incompatible in the molten state,
Moreover, they have found that they can be retained in a state of being embedded without being welded and obtained a water-absorbent sheet. However, they also absorb water from both sides and have water absorption or water permeability between two sheets of paper on both sides, and Using paper with a good basis weight of 30-60 g / m ² with good wet strength,
When laminating with a thermoplastic resin, fine powder of superabsorbent resin is previously spread and carried on the pasting surface of two sheets of paper, and the superabsorbent resin carrying surface is provided on both sides of the molten film of thermoplastic resin. It can be solved by pressure bonding, cooling and laminating. The water-absorbent freshness-maintaining paper of the present invention uses wood pulp, is added with a chemical such as an epoxy-based synthetic resin to obtain wet strength, and is manufactured without adding a sizing agent. m ² paper can be used, and the thermoplastic resin
The amount of superabsorbent resin retained on both sides of the thermoplastic resin increases or decreases depending on the required amount of water absorption so that the thickness is 50μ, but it can be made proportional to that amount so that two sheets of paper can be pasted and not peeled off. The total amount of super absorbent resin is 300-150
It may be supported so as to absorb 0 g of water.

(Function) The water-absorbent freshness-maintaining paper according to the present invention has fine particles of a highly water-absorbent resin held between the paper layer and the thermoplastic resin layer, and the paper layer has no water absorption or water permeability. Since it is made of paper or non-woven fabric that has wet strength while having,
Water drops attached to vegetables have the function of absorbing water in the paper layer or passing through the paper layer and being absorbed by the superabsorbent resin, and the paper layer also has wet strength, so it will be broken even when rubbed during transportation. It has the effect of preventing this.

(Examples) The present invention will be described according to examples.

Example 1. Water-resistant paper 2 having a basis weight of 43 g / m ² which was made from softwood bleached kraft pulp as a main raw material and polyamide epichlorhydrin as a water resistance enhancer was added to the pulp in an amount of 0.5% by weight.
When laminating the sheets with molten polyethylene, the water-absorbent resin powder consisting of a sodium acrylate polymer with an average particle size of 40μ is applied to the laminating surfaces of the two waterproof papers at a rate of about 1 per square meter.
It was evenly dispersed and supported so as to have a weight of 4 g, and a molten thin film of molten polyethylene having a thickness of about 30 μ was superposed so as to be sandwiched, compressed, and cooled to obtain a freshness maintaining paper.

In addition, as a bonding device, a device capable of manufacturing a bonding paper by using a T-die, a melted film flowing down to a contact point between a cooling roll and a press roll, and supplying paper from both sides of the T-die may be used. .

The freshness-maintaining paper obtained has a basis weight of about 100 g / m ² and 33 cm x 55 c.
The thing that can be cut to the size of m is just a thin paperboard shape, so even if you hold one, it will not hang from the middle,
It is easy to handle, and when actually storing lettuce rain and dew wet in a cardboard box, one sheet was placed as an underlay or an insole and sealed. Absorbs water and leaves are not damaged due to wetness.

Example 2. Waste paper pulp obtained by deinking newspaper waste paper was used, and polyamide picrol hydrin was used as a water resistance enhancer against pulp.
4% by weight was added, and polyacrylic amide as a paper strength additive was added to 0.5% by weight of pulp, and when paper-making was performed using two sheets of water-resistant paper having a basis weight of 50 g / m ² and fused polyethylene,
A powder of super-absorbent resin consisting of acrylic acid and vinyl alcohol copolymer with an average particle size of 10μ was sprayed and supported so that the average particle size was 3g / m ² on the pasting surface. After pressing and crimping more, cool down,
A freshness-maintaining paper of about 115 g / m ² was obtained.

It was used as an insole of a corrugated cardboard for transporting lettuce and transported in the same manner as in Example 1. The contact surface was good without damage.

(Effects of the invention) As described above, the present invention is easy to handle because it is water-absorbent or water-permeable and has a wet strength paper laminated with a thermoplastic resin. Since the resin powder is held between the paper and the thermoplastic resin film, it absorbs excess water such as vegetables, flowers, fruits, etc. of the package that causes putrefaction, and transports it without damaging the package again. It is possible. In addition, since the paper itself is rigid, the conventional product is thin and it is too flexible, so workability is poor and it bends according to the shape of the package, especially about 20% of the inner dimension in the longitudinal direction of the packaging box. Although it was necessary to use long ones, the cost can be reduced because it can be the same size as the inner size of the packaging box, and the wet strength of the paper on both sides is good, and the thermoplastic resin is used for bonding. Therefore, even if it gets wet, there is no fear of it breaking or peeling off and sticking to the package. Furthermore, by utilizing the property that it does not break even if it contains water, it is equivalent to the water absorption of super absorbent polymer. It is useful in that it can be used as a cold insulating paper by absorbing water and then freezing the sheet.

Claims (2)

[Claims] 1. A laminated paper obtained by fusing two sheets of water-absorbing or water-permeable and wet-strength with a thermoplastic resin, wherein a thermoplastic resin layer formed between the paper layers and both sides thereof are formed. Freshness-maintaining paper made by holding a fine superabsorbent resin between it and the paper layer. 2. A step of pre-spraying and carrying a fine super absorbent polymer on the bonding surface of two sheets of paper having water absorption or water permeability and having wet strength, and on both surfaces of a molten film of a thermoplastic resin. A method for producing freshness-maintaining paper, which comprises the steps of pressing and cooling the superabsorbent resin-supporting surface of two sheets of paper, that is, the bonding surface, and then bonding them together.