[0001] This invention relates to the use of a neutral paper as a package material for a
photosensitive material or a tube being in contact with or close to a photosensitive
material.
[0002] Papers used as materials for photosensitive materials such as a protecting sheet
or a paper tube are made from chemical pulp (JP-A-58-43730) and therefore, the yield
of the pulp from wood is low resulting in high costs.
[0003] On the other hand, papers made from high yield pulp are used in a wide range for
various packaging materials such as a paperboard because of their low price and high
rigidity. The high yield pulp includes mechanical pulp produced by a mechanical process
such as groundwood pulp, refiner groundwood pulp and thermomechanical pulp and partially
chemically processed pulp produced by a partial chemical process such as chemigroundwood
pulp and chemithermomechanical pulp.
[0004] The mechanical pulp is not preferred for packaging materials for photosensitive materials
because it contains lignin and resin extracts of wood in addition to cellulose. The
partially chemically processed pulp is also not preferred for a packaging material
for a photosensitive material because it contains a high amount of lignin. Therefore,
the partially chemically processed pulp has not been used for packaging materials
for photosensitive materials. If a conventional paper made from partially chemically
processed pulp is used as a packaging material for photosensitive materials, it adversely
affects the photosensitive material such as by fogging.
[0005] It is the object of the present invention to provide a neutral paper which is cheep
and does not adversely affect the photosensitive material.
[0006] Said object is achieved by use of a neutral paper which comprises 20 to 100% of partially
chemically processed pulp produced in a 65 to 95% yield by using a cooking agent consisting
essentially of NaOH, Na₂CO₃, NaHCO₃, Na₂SO₃, NaHSO₃ or a combination thereof and which
has a pH of 6 to 9, as a package material for a photosensitive material, and the use
of said neutral paper as a tube being in contact with or close to a photosensitive
material.
[0007] The use of Na₂S as a cooking agent adversely affects photosensitive materials.
[0008] When Na₂SO₃ and Na₂CO₃ are used in combination as the cooking agent in the monosulfite
process, the sensitivity of a color photographic paper is increased which is caused
by the acidity of the paper.
[0009] When the pH is not less than 6, the increase of the sensitivity is, however, within
a tolerance limit, particularly, when the pH is not less than 7, an increase of the
sensitivity does not occur.
[0010] When NaOH and Na₂CO₃ are used in combination as the cooking agent in the soda process,
the sensitivity of a color photographic paper is decreased which is caused by the
alkali in the paper.
[0011] When the pH is not more than 9, the decrease of the sensitivity is within a tolerance
limit; particularly, when the pH is not more than 8,5, a decrease of the sensitivity
does not occur.
[0012] The partially chemically processed pulp includes semichemical pulp, chemiground pulp
and chemithermo-mechanical pulp produced in a yield of 65 to 95%
, preferably 80 to 90%. The yield is indicated as yield from wood chips to paper, corresponding
to the cooling yield.
[0013] The neutral paper may be composed of the above partially chemically processed pulp
only, and unbleached kraft pulp may be added to the partially chemically processed
pulp in order to prohibit breaking during paper making and to improve the weakness
due to lignin. The partially chemically processed pulp is produced in the partially
chemically processed process and contains a high amount of lignin.
[0014] To increase the quantity of the partially chemically processed pulp is preferred
for products which need light-shielding because of a high opacity.
[0015] The pH of the neutral paper is adjusted to 6 to 9, preferably 6.5 to 8.5 according
to JIS P 8113 § 4,2. If the pH of the neutral paper needs to be raised to 6 to 9,
an addition of NaOH, KOH or other alkalies is suitable.
[0016] The use of NaOH is most preferred. If the pH needs to be lowered, various acids such
as H₂SO₄, HCl and CH₃COOH and salts which are acidic in an aqueous solution such as
aluminum sulfate can be used. Aluminum sulfate is most preferred.
[0017] Some photosensitive materials are not strongly affected by acids and alkalis. In
this case the neutral paper can be blended with corrugated board old papers, unbleached
kraft old papers, or deinked pulp in order to save costs and resources. The above
blending materials are restricted to those which hardly adversely affect the photosensitive
materials. Alternatively they are removed by washing during the breaking process.
[0018] The content of the partially chemically processed pulp is from 20 to 100%, preferably
from 50 to 100%, more preferably from 80 to 100%.
[0019] The neutral paper usually has an area weight in the range of 100 to 800 g/m², desirably
in the range of 200 to 600 g/m². The method for making the neutral paper is not restricted.
When a thick board is made, a modified starch, or a corn starch is preferably blended
in order to improve the ply bond strength during making a multi-ply paper using a
cylinder machine.
[0020] The neutral paper is preferably located to touch the photosensitive material.
[0021] The paper tube is formed by joining the above neutral paper with an emulsion adhesive
or a water-soluble adhesive having a pH of 6 to 9. When the pH of the adhesive is
less than 6 or beyond 9, an increase or decrease of the sensitivity which is out of
the tolerance limit occurs. The paper tube is usually a laminate of the neutral paper.
[0022] The emulsion adhesive includes polyvinyl acetate, polyacryl, ethylene-vinyl acetate
(EVA), and styrene-butadiene rubber (SBR). The water-soluble adhesive includes natural
polymers such as starch, sea wead, and protein, modified substances of cellulose,
and starch, and synthetic polymers such as polyvinyl alcohol (PVA) sodium polyacrylate.
[0023] The paper tube may be utilized as the core for winding a paper, a foil or a web in
addition to a photosensitive strip material.
[0024] The neutral paper may be utilized for packaging materials of various products such
as protection sheets and boxes for protecting photosensitive materials.
[0025] The neutral paper is inexpensive by using a partially chemically processed pulp of
high yield, and does not adversely affect photosensitive materials. Moreover, the
rigidity of the neutral paper is improved by a high content of lignin.
[0026] The paper tube is inexpensive as well and has a high compressive strength, and moreover,
it does not adversely affect photosensitive materials by use of an adhesive having
a pH of 6 to 9.
[0027] The following examples illustrate the invention.
Example 1
Pulp:
[0028]
- Material:
- hardwood (L material)
- Cooking Agent:
- Na₂SO₃ and Na₂CO₃
- Yield:
- 83 %
- pH:
- 7.5 (adjusted with NaOH)
Neutral Paper:
[0029] area weight : 380 g/m².
Example 2
Pulp:
[0030]
- Material:
- hardwood (L material)
- Cooking Agent:
- NaOH and Na₂CO₃ Yield: 90 %
- pH:
- 8.5 (adjusted with Al₂(SO₄)₃)
Neutral Paper:
[0031] area weight : 380 g/m².
Example 3
Pulp:
[0032] The same pulp as Example 2: 80 %
Soft wood unbleached kraft pulp: 20 % (NUKP)
pH: 8.0 (adjusted with Al₂(SO₄)₃)
Neutral Paper:
[0033] area weight : 380 g/m².
Comparative Example 1
[0034] Comparative Example 1 is the same as Example 1 except of using unadjusted pulp of
pH 5.
Comparative Example 2
[0035] Comparative Example 2 is the same as Example 2 except of using unadjusted pulp of
pH 9.5.
Conventional Example 1
Pulp:
[0036] Soft wood bleached sulphite pulp: 100 % (NBSP)
Material: soft wood (N material)
Cooking Agent: H₂SO₃, NaHSO₃ and Na₂SO₃
Yield: 46 %
pH: 5.0
Paper:
[0037] area weight: 400 g/m².
[0038] The above papers were placed in an atmosphere of 20°C and 65 % RH for two days to
adjust the moisture, and were cut into sizes of 4 cm x 15 cm. The papers were packaged
together with color photographic papers in seal by moistureproof bags, kept at 50°C
for five days and then taken out. The color photographic papers were exposed and developed,
and the exposure index according as 0,5 of reflection density was measured. The moistureproof
bags have a water vapor transmission of less than 0,5 g/m² in 24 hours and an aluminum
foil with a thickness of 7 um.
[0039] A package bag with photographic papers alone was provided as a blank. The exposure
index of the blank was subtracted from the exposure index of the above samples and
the results are indicated as variation of exposure index in Table 1.
Table 1
Samples |
Variation of Exposure Index |
Example 1 |
0 |
Example 2 |
-0.01 |
Example 3 |
+0.01 |
Comparative Example 1 |
+0.07 |
Comparative Example 2 |
-0.05 |
Conventional Example 1 |
+0.01 |
Example 4
[0040] Paper tubes were made of the paper of Examples 1, 2 or 3 or Conventional Example
1 using a polyvinyl acetate adhesive with a pH of 6.5. The paper tubes had an inner
diameter of 76,2 mm, a length of 100 mm and were 10 ply. The paper tubes were kept
at 40°C for one day to dry and then at 20°C and 65 % RH for three days to adjust the
moisture. A color photographic paper was wound on the paper tube one time and the
paper tube was placed in the above moistureproof bag in a seal. The above treatments
were conducted and the results were compared.
[0041] Moreover, other paper tubes adjusted in moisture were provided, the paper tube was
pressed in the diameter direction at 10 mm per minute by two parallel plates, and
the maximum load was measured.
[0042] The results are shown in Table 2.
Table 2
Samples |
Variation of Exposure Index |
Strength against Pressure (kg) |
Example 1 |
+0.02 |
105 |
Example 2 |
+0.01 |
97 |
Example 3 |
+0.02 |
98 |
Conventional Example 1 |
+0.02 |
60 |
1. Use of a neutral paper which comprises 20 to 100% of partially chemically processed
pulp produced in a 65 to 95% yield by using a cooking agent consisting essentially
of NaOH, Na₂CO₃, NaHCO₃, Na₂SO₃, NaHSO₃ or a combination thereof and which has a pH
of 6 to 9, as a package material for a photosensitive material.
2. The use of claim 1 wherein the partially chemically processed pulp is produced by
using Na₂SO₃ and Na₂CO₃ as the cooking agent and wherein the pH is adjusted by adding
NaOH.
3. The use of claim 1 wherein the partially chemically processed pulp is produced by
using NaOH and Na₂CO₃ as the cooking agent and wherein the pH is adjusted by adding
aluminum sulfate.
4. The use of claim 1 wherein the neutral paper is located to touch the photosensitive
material.
5. Use of a neutral paper which comprises 20 to 100% of partially chemically processed
pulp produced in a 65 to 95 % yield by using a cooking agent consisting essentially
of NaOH, Na₂CO₃, NaHCO₃, Na₂SO₃, NaHSO₃ or a combination thereof and which has a pH
of 6 to 9, as a tube being in contact with or close to a photosensitive material.
6. The use of claim 5 wherein the neutral paper is joined using an emulsion adhesive
or a water-soluble adhesive having a pH of 6 to 9.
1. Verwendung eines neutralen Papiers, welches 20 bis 100 % teilweise chemisch verarbeitete
Pulpe, hergestellt mit einer Ausbeute von 65 bis 95 % unter Verwendung eines Aufschlußmittels,
bestehend im wesentlichen aus NaOH, Na₂CO₃, NaHCO₃, Na₂SO₃, NaHSO₃ oder einer Kombination
davon, umfaßt und das einen pH-Wert von 6 bis 9 aufweist, als Verpackungsmaterial
für ein lichtempfindliches Material.
2. Verwendung nach Anspruch 1, wobei die teilweise chemisch verarbeitete Pulpe unter
Verwendung von Na₂SO₃ und Na₂CO₃ als Aufschlußmittel hergestellt wird, und wobei der
pH-Wert durch Zugabe von NaOH eingestellt wird.
3. Verwendung nach Anspruch 1, wobei die teilweise chemisch verarbeitete Pulpe unter
Verwendung von NaOH und Na₂CO₃ als Aufschlußmittel hergestellt wird, und wobei der
pH-Wert durch Zufügung von Aluminiumsulfat eingestellt wird.
4. Verwendung nach Anspruch 1, wobei das neutrale Papier so plaziert ist, daß es das
lichtempfindliche Material berührt.
5. Verwendung eines neutralen Papiers, das 20 bis 100 % teilweise chemisch verarbeitete
Pulpe, hergestellt mit einer Ausbeute von 65 bis 95 % unter Verwendung eines Aufschlußmittels,
bestehend im wesentlichen aus NaOH, Na₂CO₃, NaHCO₃, Na₂SO₃, NaHSO₃ oder einem Gemisch
daraus, umfaßt und das einen pH-Wert von 6 bis 9 aufweist, als eine Röhre, die sich
in Kontakt mit einem lichtempfindlichen Material oder in der Nähe eines lichtempfindlichen
Materials befindet.
6. Verwendung nach Anspruch 5, wobei das neutrale Papier unter Verwendung eines Emulsionshaftmittels
oder eines wasserlöslichen Haftmittels mit einem pH-Wert von 6 bis 9 gebunden wird.
1. Utilisation d'un papier neutre, qui comprend de 20 à 100 % d'une pulpe partiellement
élaborée chimiquement produite avec un rendement de 65 à 95 % en utilisant un agent
de cuisson consistant pour l'essentiel en du NaOH, du Na₂CO₃, du NaHCO₃, du Na₂SO₃,
du NaHSO₃ ou en une combinaison de ceux-ci, et qui a un pH de 6 à 9, en tant que matériau
d'emballage pour une matière photosensible.
2. Utilisation selon la revendication 1, dans laquelle la pulpe partiellement élaborée
chimiquement est produite en utilisant du Na₂SO₃ et du Na₂CO₃ en tant qu'agent de
cuisson, et dans laquelle le pH est ajusté par addition de NaOH.
3. Utilisation selon la revendication 1, dans laquelle la pulpe partiellement élaborée
chimiquement est produite en utilisant du NaOH et du Na₂CO₃ en tant qu'agent de cuisson,
et dans laquelle le pH est ajusté par addition de sulfate d'aluminium.
4. Utilisation selon la revendication 1, dans laquelle le papier neutre est place de
manière à toucher la matière photosensible.
5. Utilisation d'un papier neutre, qui comprend de 20 à 100 % d'une pulpe partiellement
élaborée chimiquement produite avec un rendement de 65 à 95 % en utilisant un agent
de cuisson consistant pour l'essentiel en du NaOH, du Na₂CO₃, du NaHCO₃, du Na₂SO₃,
du NaHSO₃ ou en une combinaison de ceux-ci, et qui a un pH de 6 à 9, en tant que tube
qui est en contact avec une matière photosensible ou à proximité immédiate de celle-ci.
6. Utilisation selon la revendication 5, dans laquelle le papier neutre est assemblé
au moyen d'un adhésif émulsion ou d'un adhésif soluble dans l'eau ayant un pH de 6
à 9.