JPH07147884A - Base paper for casing - Google Patents

Abstract

PURPOSE:To obtain a base paper for a casing, having excellent wet strength, impregnation characteristics, transparency and alkali resistance and suitable for the packaging of edible meat products such as ham and sausage by impregnating a prescribed amount of gelatin in a sheet-formed paper base material. CONSTITUTION:A sheet-formed paper base material manufactured from cellulose pulp is incorporated with 1.0-20.0wt.% (based on the bone-dry weight of the material) of gelatin and, more preferably, 0.3-5.0wt.% (based on the bone-dry weight) of a water-resistance improving agent such as a polyamide epichlorohydrin resin. The gelatin is preferably the one having a molecular weight of 100,000-300,000 and prepared by treating cattle bone and cow hide with lime.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has good wet strength and impregnation properties, and is used for producing a casing for filling meat products such as ham and sausage, which has excellent transparency and wetness. The present invention relates to a casing base paper that can impart strength to the casing.

[0002]

2. Description of the Related Art Processed meat products such as ham and sausages are manufactured by filling a tube-shaped casing with a kneaded product prepared by mixing raw materials and then subjecting it to heat treatment, sterilization treatment, smoke treatment and the like. There are natural casings and artificial casings (cellulose casings, collagen casings, plastic casings, fibrous casings, etc.), and artificial casings are cheaper and more hygienic than natural casings, and their product size is constant. Widely used due to its advantages.

However, the cellulose casing has the drawbacks of low strength and weakness to humidity, and the plastic casing cannot be smoked. Therefore, large-sized loin ham and press ham have hitherto been used. A strong fibrous casing that can smoke is used for this purpose.

The fibrous casing is a paper base material made of cellulose pulp impregnated with viscose, coagulated,
It has been regenerated, and this method is described in US Pat.
No. 105,273. Viscose is 7% by weight cellulose and 6% sodium hydroxide.
It is an aqueous solution containing and, therefore, the paper base material is required to have wet strength and alkali resistance. Such a paper substrate is disclosed in U.S. Pat. Nos. 3,135,613 and 3,275,456 in order to impart wet strength and alkali resistance capable of withstanding the above viscose impregnation. As described above, the dilute viscose liquid (cellulose content of about 1%) is pre-impregnated and regenerated.

Further, in Japanese Patent Publication No. 4-16129, when a sheet-like paper base material composed of cellulose pulp such as hemp pulp and wood pulp is produced, it is used together with pulp or a sheet of paper, non-woven fabric or the like. It is disclosed that chitosan or a chitosan salt is added, applied or immersed in the above-mentioned aqueous solution after being formed into a cardboard substrate. However, only by treating the pulp or sheet-like paper base material with only chitosan or chitosan salt, the wet strength is relatively high, but the alkali resistance is low and the strength is still insufficient.

On the other hand, a method of increasing paper strength by adding chitosan salt and polyamide epichlorohydrin resin together to a pulp slurry is disclosed in Japanese Patent Laid-Open No. 335008/53. The strength of paper made is not yet practically sufficient.

Further, in order to impart high wet strength and alkali resistance using chitosan, it is necessary to hold the chitosan in a high ratio in the pulp fibers constituting the sheet-like paper base paper. The external addition method of dipping or applying the chemicals on the sheet-shaped paper base is more efficient than the internal addition method of adding the chemicals to the papermaking. However, in the case of the external addition method, it is necessary to secure a high chemical content, and then it is necessary to use a high concentration chitosan-dissolved aqueous solution. The viscosity of the aqueous solution in which chitosan is dissolved has a relatively high viscosity, as can be seen by measuring it with a B-type viscometer, and a high concentration chitosan-dissolved aqueous solution showing a viscosity of more than 100 cps is impregnated in actual operation. Alternatively, it is inconvenient because it is difficult to handle at the time of application, unevenness of impregnation occurs, and the obtained quality varies.

The present inventors have diligently studied such a problem,
A method for producing a fibrous casing base paper in which a sheet-like base material made of cellulose pulp is treated with an aqueous solution in which chitosan or a chitosan salt and a water-proofing agent are mixed has been proposed (Japanese Patent Application No. 5-101397). According to this method, the viscosity of the chitosan-dissolved aqueous solution for impregnation can be suppressed to 100 cps or less (B-type viscometer), the operation becomes relatively easy, and the variation in the obtained quality can be relatively reduced. However, in order to maintain the wet strength and alkali resistance at a high level, it is necessary to use relatively high values for the content of chitosan and the content of waterproofing agent per sheet-shaped paper substrate after impregnation. Inevitably, therefore, the viscosity of the aqueous solution of chitosan is 100 cps or less,
It could not be lowered to a level that was slightly lower than 00cps.

In addition to the above, by using a water-proofing agent in combination with chitosan, the wet strength, alkali resistance and impregnation unevenness of the sheet-shaped paper base material could be improved considerably, but especially impregnation unevenness in pre-impregnation is still insufficient. Met. Occurrence of unevenness in pre-impregnation causes final unevenness of impregnation due to viscose.When a meat product such as ham and sausage is filled in a casing manufactured using such casing base paper, the diameter of the filled product becomes uniform. The quality is remarkably impaired, and this uniformity is one index for determining the quality of the product. Therefore, chitosan or chitosan can be used as an impregnation method that further reduces the viscosity of the chitosan-dissolved aqueous solution, facilitates adjustment during pre-impregnation, has no impregnation unevenness, and can achieve equivalent strength quality even when the chitosan content is low. A method has been proposed in which a polyvinyl alcohol-based resin (hereinafter referred to as PVA) is used in combination with a mixed solution of a salt and a water-proofing agent (Japanese Patent Application No. 5-161034).

In US Pat. No. 5,108,546, a sheet-like paper base material is treated with a combination of polyvinyl alcohol having a saponification degree of 95% or more and a cationic resin to improve wet strength and alkalinity. In US Pat. No. 5,067,104, there is disclosed a method for improving the above-mentioned properties by performing a first treatment with a thermoplastic material and a second treatment with an insolubilizing agent.

However, in these treatment methods, although the wet strength and the alkali resistance of the paper base material are relatively high, the affinity with the viscose used in the post-treatment is deteriorated, and the viscose used in the casein is processed. There remains a drawback that the impregnation of the course into the paper base material becomes poor and the integration of the paper base material and viscose is impaired, so that the strength of the casing decreases. The strength of the casing is
This is a very important item required for filling the casing with meat, and if the casing has low strength, the casing may burst when the meat is loaded. From the viewpoint of the strength of the casing, the sheet-shaped paper base material that has not been subjected to any preliminary treatment has the best affinity with viscose, and the strength of the casing is also high. However, the sheet-shaped paper base material that has not been pretreated is not practical because of its low wet strength and alkali resistance. Therefore, under the present circumstances, even if the strength of the casing is lowered to some extent, it is unavoidable to use a base paper for casing that has high wet strength and alkali resistance and good operability, but the strength of the casing is also high and other characteristics In particular, the emergence of excellent casing base paper is strongly desired.

[0012]

In view of the above situation, the present inventors have found that the wet strength and alkali resistance of the base paper for casing using a sheet-like base material composed of cellulose pulp as a raw material can As a result of extensive research on a method of improving the impregnating ability of the course, the disadvantage of the prior art is solved by containing gelatin or a mixture of gelatin and a water-proofing agent in a sheet-shaped substrate, The present invention has been completed by finding that a base paper for casing that can exhibit excellent casing strength can be obtained.

The object of the present invention is to provide a base paper for a casing comprising a sheet-like paper base material which has good viscose impregnation property in the post-treatment of the base material, excellent wet strength, and can improve the strength of the casing. To provide.

[0014]

The first aspect of the present invention is a base paper for casing, characterized in that the sheet-shaped paper base material contains gelatin in an amount of 1.0 to 20.0% by weight based on the absolute dry weight. A second aspect of the present invention is the casing base paper according to claim 1, wherein the sheet-like paper base material contains a water-proofing agent in an amount of 0.3 to 5.0% by weight based on the absolute dry weight.

The gelatin used in the present invention is a protein obtained by partially hydrolyzing a main protein (collagen) that constitutes animal skins and bones, and is used for the production of jellies, marshmallows and the like. , Pharmaceuticals used for manufacturing hard capsules, soft capsules, films,
Edible gelatin is selected from among those used for photography such as photographic paper and for industrial use such as adhesives and abrasives. In particular,
Edible gelatin produced by lime (alkali) treatment method from beef bone and cowhide and acid treatment method from pigskin is preferably used, and its molecular weight is preferably selected from the range of 100,000 to 300,000. There is no limit.

One of the indexes showing the quality of gelatin is "jelly strength", which is the hardness of the jelly when a 6.2 / 3% solution of gelatin is hardened, as specified in JISK6503. It usually indicates 50 to 30
Although it is in the range of 0 Bloom, there is no particular limitation on the jelly strength in the present invention, but gelatin having a relatively high jelly strength of 200 Bloom or more is preferably used.

As a method for obtaining an aqueous solution in which gelatin is used in the present invention, it is necessary to first dissolve gelatin in water to form an aqueous solution. Two methods of dissolving gelatin are a swelling dissolution method and a direct dissolution method. There is. The swelling dissolution method is a method in which a commercially available gelatin powder is previously swollen with water and then heated and dissolved, but gelatin after swelling in water is not easy to stir, and it takes time to raise the temperature. Because it requires
The dissolution time is slightly longer. For example, as an example of this method, when the solid content concentration of gelatin is less than 10% by weight, the gelatin is swollen with stirring at 10 to 25 ° C. for 30 to 60 minutes to allow the gelatin particles to absorb water sufficiently, The temperature is raised to 40 to 7 by indirect heating or direct heating.
Dissolve the gelatin at 0 ° C. with continuous stirring.

On the other hand, the direct dissolution method is a method in which gelatin powder is directly added to warm water while stirring and dissolved, but gelatin can be dissolved in an extremely short time. In this method, it is necessary to consider so that the gelatin can be sufficiently dispersed, but the dissolution time is, for example, 1 to 50-70 ° C.
0 to 15 minutes.

In the present invention, any of the above-mentioned methods may be adopted as the method for dissolving gelatin. However, in order to ensure sufficient dispersion, the type, volume, number, etc. of the vessel and agitator for dissolution should be gelatin. It needs to be decided depending on the scale of dissolution and time factors. In particular, local heating or excessive heating, whether direct or indirect heating, causes deterioration of the physical properties of gelatin, so it is necessary to pay close attention.

The concentration of the gelatin aqueous solution used in the present invention is in the range of 0.5 to 10.0% by weight, preferably 1.0 to 5.0% by weight in terms of solid content concentration. When the concentration is less than 0.5% by weight, the workability is very good, but the gelatin cannot be contained in the paper base material to the extent that the strength is sufficiently expressed. Conversely, when the concentration exceeds 10% by weight. The higher the temperature, the higher the viscosity of the aqueous gelatin solution as the pretreatment liquid, the difficulty in controlling the gelatin content and the handling of the pretreatment liquid, and the poor operability. The aqueous gelatin solution used in the present invention has a viscosity of the aqueous solution as compared with a known pretreatment solution such as an aqueous solution in which chitosan is dissolved, for example, the solid content concentration of the aqueous gelatin solution predicted to give the highest solution viscosity. Even at 10% by weight, the viscosity at 35 ° C. measured by the B-type viscometer can be kept as low as about 35 cps.

The content of gelatin is 1.0 to 20.0% by weight, preferably 2.5, based on the absolute dry weight of the sheet-shaped paper base material.
˜13.0% by weight. When the content is less than 1.0% by weight, the transparency of the casing is excellent, but the wet strength is not sufficiently expressed, and when the content exceeds 20% by weight, the wet tensile strength after containing gelatin increases. For that reason, the wet tensile strength of the casing after treated with the post-treatment viscose aqueous solution does not become high, so that it is wasted in terms of cost, and the transparency of the casing is lost, which is not suitable.

If the wet tensile strength of the sheet-shaped paper base material after containing gelatin is 0.70 kg / 15 mm or more, no paper breakage will occur in the next step and the viscose aqueous solution will be treated without impairing operability. It can be applied onto the pretreated sheet-shaped paper substrate. The wet tensile strength of the casing after applying the coating treatment in this way is 5.5 kg.
/ 15 mm or more, and the strength as a casing product is sufficiently practical.

On the other hand, in the present invention, the sheet-shaped paper base material can be pretreated with gelatin alone, but if a water resistant agent is mixed with an aqueous gelatin solution and used in combination, the amount of expensive gelatin used is reduced. be able to. Therefore, the viscosity of the gelatin aqueous solution used for the pretreatment can be reduced by that much, and gelatin can be uniformly contained in the paper base material, which is advantageous in terms of manufacturing cost, workability, and quality. In this case, the combination with the gelatin content is such that the content of the water-proofing agent in the content of gelatin is 0.3 to 5.0% by weight, preferably 0.7 to 5.0% based on the absolute dry weight of the sheet-shaped paper base material.
Used together in the range of 1.8% by weight.

If the content of the waterproofing agent is less than 0.3% by weight, the effect of using the waterproofing agent together is not exhibited, and it is meaningless to use the waterproofing agent together, which is not suitable. When it exceeds 5.0% by weight, the wet strength of the paper base material after pretreatment with an aqueous solution containing gelatin and a water-proofing agent can be made to be an extremely high level. The wet strength of the casing after the treatment is not high, which is not economical and is unsuitable because the transparency of the casing is impaired. In addition, excessive use of the water-proofing agent causes the viscosity of the aqueous solution for pretreating the sheet-shaped paper base material to rise conversely, causing unevenness of impregnation into the paper base material and subsequent application / impregnation of the viscose aqueous solution. Is unfavorable because it causes the deterioration of the wet strength of the casing and causes the quality variation.

On the other hand, examples of the water-proofing agent which can be used together with gelatin include urea formaldehyde resin, melamine formaldehyde resin, glyoxal, dial starch, polyamide epichlorohydrin resin, polyethyleneimine and the like. Formalin-free polyamide epichlorohydrin resin is preferably used as the waterproofing agent. When gelatin is used in combination with a water-proofing agent, it is preferable to first prepare an aqueous solution in which gelatin is dissolved and then add the water-proofing agent to the aqueous solution.

The sheet-shaped paper base material for the present invention includes:
For example, wood pulp such as bleached kraft pulp, hemp pulp (manila, sisal, flax, cannabis, jute), pulp from non-wood fibers such as Kozo and Mitsumata, etc., or these pulps are appropriately selected. Paper obtained by making a paper by a known wet paper machine using the mixed pulp, preferably hemp pulp as a paper stock is suitably used.

Since pulp is used to make porous paper, it is preferably used in an unbeaten state (freeness of 650 to 750 mlcsf). However, since beating increases binding strength, the freeness is lowered to 500 mlcsf depending on the application. All or part of the pulp may be used.
Further, in order to impart further strength to the sheet-shaped paper base material, it is preferable to add a known paper-making chemical such as a water resistant agent or a wet paper strength enhancer to the paper stock for papermaking. The basis weight of the sheet-shaped paper base material varies depending on the desired application, but is appropriately selected and used in the range of 15 to 30 g / m ² for the casing base paper.

As a method of incorporating gelatin or gelatin and a water-proofing agent into the sheet-shaped paper base material, a method of impregnating the sheet-shaped paper base material with an aqueous solution in which the above compound is dissolved, a size press, a roll coater, a brush coater or the like is used. Examples thereof include a method of applying the aqueous solution, but the method is not particularly limited thereto, and other treatment methods can be adopted.

Since the present invention has the above-mentioned constitution, it becomes extremely easy to add gelatin or gelatin and a water-proofing agent to the sheet-shaped paper base material when producing the base paper for casing, and the paper containing the above-mentioned compound. It is possible to obtain a base paper for a casing which has excellent wet strength of the substrate and, after finishing into a casing, can give excellent wet strength and transparency.

[0030]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the examples and comparative examples,% means% by weight unless otherwise specified.

Example 1 Commercially available Philippine hemp pulp (product number: S-2B) that had not been beaten (freeness of 690 mlcsf) had a slurry concentration of 2.
Polyamide epichlorohydrin resin (WS-570, manufactured by Japan PMC) per weight of absolutely dry pulp at 5% was 1.5.
%, And sufficiently stirred to prepare a paper material, and a sheet-shaped paper base material having an absolute dry basis weight of 23 g / m ² was prepared in a laboratory paper machine.

On the other hand, a commercially available gelatin (product number: MJ, made by Nitta Gelatin, jelly strength: 220 Bloom) produced by a lime treatment method using beef bone as a raw material is stirred at a temperature of 60.
Pour into warm water at ℃ at a rate of 11.1 parts per 100 parts of water, continue stirring for 15 minutes to dissolve by direct dissolution method, prepare a gelatin aqueous solution having a solid content concentration of 10.0%, and prepare this aqueous solution. Was further diluted with water to give an aqueous solution having a solid content concentration of 1.0%.

The sheet-shaped paper base material was impregnated with the aqueous gelatin solution in an experimental impregnation machine, and the excess liquid was squeezed out using a squeezing machine made of a rubber roll, and the wet impregnation weight was set to 50 g / m ² . Then, it was dried in a hot-air circulation type oven adjusted to a temperature of 105 ° C. until the water content became 3.8%. The content of gelatin in the obtained impregnated paper base material was 2.2% based on the weight of the absolutely dry sheet-like paper base material before the impregnation treatment.

On one side of this gelatin-treated paper base material, an aqueous viscose solution having a cellulose content of 7% in terms of solid content (solution viscosity: 5000 cps by B-type viscometer) was applied with an applicator roll to give a wet weight of 993 g / m 2.
² (69.5 g / m ^{2 in} terms of solid content) was applied, and after 30 seconds, it was immersed in an aqueous ammonium sulfate solution having a concentration of 30% in terms of solid content for 20 minutes without being dried. Then, the paper base material was taken out, further immersed in a 5% concentration sulfuric acid aqueous solution in terms of solid content for 20 minutes, then taken out and washed with water,
Dry until the water content becomes 6.0% and the absolute dry basis weight is 9
A 3.0 g / m ² casing was prepared.

Wet tensile strength and casing transparency of a gelatin-treated sheet-shaped paper substrate (hereinafter, not coated with viscose) and a casing were measured and evaluated by the following methods. (1) Wet tensile strength Measured according to JIS P 8135, the wet tensile strength of the gelatin-treated and untreated sheet-shaped paper base materials is 0 from the viewpoint of operability in the step of finishing the casing.
A value of 70 g / 15 mm or more was evaluated as good, and a value of 70 g / 15 mm or more was evaluated as unacceptable. On the other hand, the wet tensile strength of the casing is 5.5 kg from the viewpoint of preventing deformation and damage of the product.
If it is / 15 mm or more, it is shown as good, and if it is less than that, it is shown as x and it is shown as x. (2) By visually observing the transparent casing, those with excellent transparency are marked with ⊚, those with good transparency are marked with ○, and there is unevenness in transparency, but there is no problem in practical use. Is indicated by a triangle, and those that are completely opaque and are not suitable for practical use are indicated by an x.

Example 2 The same gelatin aqueous solution as in Example 1 was used, and a polyamide epichlorohydrin resin (trade name: W
S570, manufactured by Japan PMC) were mixed so that the concentrations of the mixed gelatin and water-proofing agent aqueous solutions after conversion into solids were 0.6% and 0.5%, respectively. Example 1
The sheet-shaped paper base material was impregnated with the prepared mixed aqueous solution in the same manner as in 1. to prepare a gelatin-treated paper base material. The contents of gelatin and waterproofing agent in the obtained base material were 1.3% and 1.1%, respectively, based on the weight of the absolutely dry paper base material before treatment.
Met. This gelatin and water-proofing agent-treated paper base material were treated with an aqueous viscose solution in the same manner as in Example 1 (wet weight 993 g / m ² , solid content weight 69.5 g).
/ M ² ), and a casing having an absolute dry basis weight of 93.1 g / m ² was prepared, and wet tensile strength and transparency were evaluated.

Example 3 An aqueous solution containing gelatin alone at a concentration of 8.0% in terms of solid content was used, and the coating amount of viscose was 94 by wet weight.
A gelatin-treated paper base material (gelatin content is the weight of the absolutely dry paper base material before gelatin treatment) in the same manner as in Example 1 except that the amount was 3 g / m ² (66.0 g / m ^{2 in} terms of absolute dry weight). 1 hit
7.4%) and an absolute dry weight of 93.0 g / m ² were prepared, and the quality of each was evaluated.

Example 4 The same gelatin aqueous solution as in Example 1 was used, and a polyamide epichlorohydrin resin (trade name: W
S570, manufactured by Nippon PMC Co., Ltd.) were mixed so that the concentrations of the gelatin and the water-proofing agent aqueous solution after mixing were 8.0% and 0.5% in terms of solid content, respectively. Example 1
The sheet-shaped paper base material was impregnated with the prepared mixed aqueous solution in the same manner as in 1. to prepare an impregnated paper base material. The contents of gelatin and water-proofing agent in the obtained substrate were 17.4% and 1.1%, respectively, based on the absolute dry weight of the untreated paper substrate. This treated substrate was treated with an aqueous viscose solution in the same manner as in Example 1 (wet weight: 939 g /
m ² , solid content weight: 65.7 g / m ² ), absolutely dry weight 9
A casing of 3.0 g / m ² was prepared, and the wet tensile strength and transparency were evaluated.

Example 5 An aqueous solution containing gelatin alone at a solid content concentration of 9.0% was used, and the coating amount of viscose was 93 by wet weight.
A gelatin-treated paper base material was used in the same manner as in Example 1 except that the amount was 6 g / m ² (65.5 g / m ^{2 in} terms of absolute dry weight). .6%)
A casing having an absolutely dry weight of 93.0 g / m ² was prepared, and the wet tensile strength and the transparency were evaluated.

Example 6 An aqueous solution of gelatin alone having a solid concentration of 2.0% was used, and the coating amount of viscose was 986 g / m 2 by wet weight.
Example ² except ² (absolute dry weight of 69.0 g / m ² ).
In the same manner as above, a gelatin-treated base material (gelatin content was 4.3% based on the absolute dry weight of the untreated paper base material) and a casing having an absolute dry weight of 93.0 g / m ² were prepared, and the wet tensile strength was And the transparency was evaluated.

Example 7 The same aqueous gelatin solution as in Example 1 was used, and a polyamide epichlorohydrin (trade name: WS5) was used as a waterproofing agent.
70, manufactured by Japan PMC), and the concentrations of the gelatin and the water-proofing agent aqueous solution after the mixing are calculated to be 0.
It was adjusted to 6% and 2.2%. The sheet-like paper base material was impregnated with the prepared mixed aqueous solution in the same manner as in Example 1 to prepare an impregnated paper base material. The contents of gelatin and water-proofing agent in the resulting cuts were 1.3% and 4.8%, respectively, based on the absolute dry weight of the untreated paper substrate.
This treated base material was treated with a viscose aqueous solution in the same manner as in Example 1 (wet weight: 980 g / m ² , solid content weight: 68.6 g / m ² ) to obtain an absolute dry weight of 93 g / m ^2.
A m ² casing was prepared and evaluated for wet tensile strength and transparency.

COMPARATIVE EXAMPLE 1 Using an aqueous solution containing 0.4% gelatin based on the solid content, the amount of viscose applied was 98 by wet weight.
A gelatin-treated substrate was used in the same manner as in Example 1 except that the amount was 7 g / m ² (absolute dry weight of 69.1 g / m ² ). 9%) and an absolutely dry weight of 93.0 g / m ² were prepared, and wet tensile strength and transparency were evaluated.

Comparative Example 2 The same gelatin aqueous solution as in Example 1 was used, and a polyamide epichlorohydrin resin (trade name: W
S570, manufactured by Japan PMC) were mixed so that the concentrations of the mixed gelatin and the water-proofing agent aqueous solution in terms of solid content were 0.3% and 0.5%, respectively. Example 1
A sheet-shaped paper base material was impregnated with the prepared mixed aqueous solution in the same manner as in (1) to prepare an impregnated paper base material. The contents of gelatin and water-proofing agent in the obtained paper substrate were 0.7% and 1.1%, respectively, based on the absolute dry weight of the untreated paper substrate. This treated base material was treated with an aqueous viscose solution in the same manner as in Example 1 (wet weight: 994 g / m 2).
² , solid content weight: 69.6 g / m ² ), and an absolute dry weight of 93.
A 0 g / m ² casing was prepared and evaluated for wet tensile strength and transparency.

Comparative Example 3 The same gelatin aqueous solution as in Example 1 was used, and a polyamide epichlorohydrin resin (trade name: W
S570, manufactured by Japan PMC) were mixed so that the concentrations of the gelatin and the water-proofing agent aqueous solution after mixing were 8.1% and 2.7% in terms of solid content, respectively. Example 1
A sheet-shaped paper base material was impregnated with the prepared mixed aqueous solution in the same manner as in (1) to prepare an impregnated paper base material. The contents of gelatin and waterproofing agent in the obtained paper substrate were 17.6% and 5.9%, respectively, based on the absolute dry weight of the untreated paper substrate. This treated base material was treated with an aqueous viscose solution in the same manner as in Example 1 (wet weight: 923 g / m 2).
² , solid content weight: 64.6 g / m ² ), and an absolute dry weight of 93.
A 0 g / m ² casing was prepared and evaluated for wet tensile strength and transparency.

Comparative Example 4 The same gelatin as in Example 1 had a concentration of 11.
A 0% aqueous solution was prepared and used, and the applied amount of viscose was 921 g / m ² in wet weight (64.5 g / m in absolute dry weight).
m ² ), except that the gelatin-treated base material (gelatin content is 23.9% based on the absolute dry weight of the untreated paper base material) and the absolute dry weight are 93.0 g / m in the same manner as in Example 1. The casing of No. ² was prepared, and the wet tensile strength and the transparency were evaluated.

Comparative Example 5 The same sheet-like paper substrate used in Example 1 was tested for wet tensile strength without pretreatment with gelatin and then this paper substrate was processed in the same manner as in Example 1 Apply the course (wet weight 1000 g / m ² , solid content weight 70 g / m ²
m ² ), and a casing having an absolutely dry weight of 93.0 g / m ² was prepared, and wet tensile strength and transparency were evaluated.

Comparative Example 6 The same sheet-like paper base material used in Example 1 was impregnated in the same manner as in Example 1 with an aqueous viscose solution in which 2% of the cellulose was dissolved in terms of solid content, followed by solidification. 5% in minutes
Cellulose was regenerated with an aqueous sulfuric acid solution having a concentration, washed with water, and then dried to prepare a pretreated paper base containing regenerated cellulose in an amount of 4.3% based on the absolute dry weight of the untreated paper base. Then, (986 g / m ² wet weight, 69 g / m ² in solid weight) viscose applied in the same manner as in Example 1 to the paper substrate, and oven-dry weight of 93.0 g / m ² A casing was prepared and evaluated for wet tensile strength and transparency.

Table 1 shows the measurement and evaluation results obtained in the examples and comparative examples.

[0049]

[Table 1]

As can be seen from Table 1, the base paper for casein of the present invention containing gelatin or gelatin and a water-proofing agent in a predetermined amount is excellent in wet tensile strength and has good affinity with viscose, so that it is finished into a casing. After that, the casing can be imparted with high transparency and excellent wet tensile strength (Examples 1 to 6). On the other hand, when the content of gelatin or gelatin and water-proofing agent is small, there is no particular problem after finishing the casing, but the wet strength is poor at the stage of the base paper for casing (0.7 kg / 15 mm
The following) may cause a problem in workability when applying viscose (Comparative Examples 1 and 2).

On the other hand, when the content of gelatin or gelatin and the water-proofing agent is large, the wet tensile strength of the base paper for casing is remarkably high, but the transparency of the casing is low after finishing the casing and the wet tensile strength is poor ( 5.5k
g / 15 mm or less) (Comparative Examples 3 and 4). When the sheet-shaped paper base material is not subjected to any pretreatment, the transparency of the casing after finishing the casing is high and the wet tensile strength is excellent, but the wet strength at the stage of the base paper for casing is extremely low, Since the paper breaks when applying viscose, it cannot be put to practical use (Comparative Example 5). In the conventional method of pretreating the sheet-shaped paper base material with a dilute aqueous solution of viscose, there is no problem at the stage of the base paper for casing, but the transparency and wet strength are slightly inferior after finishing the casing,
Although it can be barely put into practical use, it is not at a satisfactory level (Comparative Example 6).

[0052]

As described in detail above, the base paper for casing of the present invention is excellent in wet tensile strength. Therefore, when this base paper is used, excellent workability at the stage of processing into a casing can be secured, The effect is that a casing having excellent transparency and wet tensile strength after being finished into a casing can be provided.

Claims (2)

[Claims] 1. A base paper for casing, characterized in that the sheet-shaped paper base material contains gelatin in an amount of 1.0 to 20.0% by weight based on the absolute dry weight. 2. The base paper for casing according to claim 1, wherein the sheet-like paper base material contains a water-proofing agent in an amount of 0.3 to 5.0% by weight based on the absolute dry weight.