JPH03199201A - Prevention of deterioration of cellulose acetate - Google Patents

Abstract

PURPOSE:To impart excellent weather resistance, moist heat resistance, dark- moist heat resistance and shelf stability and usefully prevent deterioration of a substrate of a photographic material, an optical filter, a protecting layer for a polarizing film, etc., by adding a metal deactivator to cellulose acetate. CONSTITUTION:Prevention of deterioration is contrived by addition of a metal deactivator (e.g. compound of formula I) to cellulose acetate. In addition, a peroxide decomposer (e.g. compound of formula II) and a radical chain terminator (e.g. compound of formula III) are preferably added in combination therewith.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is directed to the production of cellulose acetate suitable for use in supports for photographic light-sensitive materials, optical filters, films for protective layers of polarizing films, release films, etc. It concerns the Deterioration Prevention Act.

[Conventional technology]

Fatty acid cellulose esters, such as cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate, are usually produced using sulfuric acid as a catalyst, but this sulfuric acid reacts with the hydroxyl groups of cellulose to form sulfuric esters. to make.

This bound sulfuric acid and ai! remaining in the fiber tissue! The sulfuric acid of IIl is desorbed and removed as much as possible by boiling stabilization treatment, but extremely small amounts of sulfuric ester and free silicic acid remain in the fatty acid cellulose ester and act as a catalyst for hydrolysis, so it may not last long. This is the main cause of deterioration due to storage, especially poor thermal stability, that is, coloring or decomposition due to heat, and molecular chain scission. This can be neutralized and stabilized by adding acid salts, carbonates, oxalates, etc. of potassium, sodium, calcium, barium, aluminum, etc. (US Pat. Nos. 3047561 and 30898).
No. 71, No. 2614941, etc.) are known. However, when producing fatty acid cellulose esters industrially, salts of these weak acids are gradually added in excess, so they remain in the fiber tissue without bonding with sulfuric esters or free sulfuric acid, causing decomposition and molecular chain formation. Although deterioration such as cutting can be prevented, on the contrary, it acts as a catalyst for the production of colored substances, which has the disadvantage of significantly impairing the hue.

Furthermore, since cellulose as a raw material for fatty acid cellulose ester is made from natural products such as linter and pulp, it contains many impurities that cause coloration. Therefore, in order to remove this coloring agent, it is necessary to perform various treatments such as bleaching, high-temperature pressurization, and filtration when refining linter or pulp or producing fatty acid cellulose ester. In addition, fatty acid cellulose ester usually contains a plasticizer,
The effects of heat on these substances must also be considered.

Common plasticizers include dimethyl phthalate, diethyl phthalate, triphenyl phosphate,
Examples include tricresyl phosphate, dimethoxyoxyethyl phthalate, glycerol triacetate, 0-1 or p-)luene ethyl sulfonamide, butylphthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, etc. .

In addition, Japanese Patent Publication No. 61-14168 describes polycaprolactone polyol as a plasticizer for acetyl cellulose, and Japanese Patent Publication No. 47-760 describes mixing a polyester urethane resin into a triacetic acid cellulose coating. Further, JP-A-61-69845 describes mono- or dialkyl phosphates in which non-esterified hydroxyl groups are in the form of m-superacids as peeling aids for cellulose ester films.

In order to obtain a fatty acid cellulose ester with excellent transparency and heat resistance, it is necessary to use highly purified cellulose as a raw material, and also to absorb sulfuric acid, which is a reaction catalyst, into the fiber tissue in the form of bound sulfuric acid. It is desirable to use a fatty acid cellulose ester that has a small residual amount and ash content and from which coloring substances have been removed, and it is also desirable to use additives such as plasticizers that have high thermal stability.

However, as mentioned above, there are technical and economical limits to preventing the deterioration of fatty acid cellulose esters solely by relying on the purity and quality of the constituent raw materials. Therefore, it is generally done to mix and match appropriate deterioration inhibitors, and conventional deterioration inhibitors for fatty acid cellulose esters include epoxy compounds, weak organic acids, saturated polyhydric alcohols, and oxidation inhibitors for organic materials used in boat fishing. For example, sulfur-based antioxidants such as phosphite compounds, hindered phenols, and thioethers are known (U.S. Pat. No. 2,917,398, U.S. Pat. No. 3,723,147,
4,269,629, 4,137,201, 3,723,147, JP 6F-128036,
No. 57-78431, No. 55-13765, Special Publication No. 61-45654, etc.).

In the case of neutralization and stabilization treatment with a weak acid salt, even when the ash content of the fatty acid cellulose ester was 0.01% by weight or more, which was a large amount of impurities, the effect of preventing the resin from discoloring during heating was achieved. Because it acts to cleave molecular chains, the degree of polymerization decreased significantly and physical properties deteriorated. In addition, when a weak organic acid, an epoxy compound, and a phosphite compound are added to fatty acid cellulose ester, the deterioration of physical properties is considerably improved compared to when a weak organic acid and a phosphite compound are added. This was not completely satisfactory, and furthermore, the coloring property upon heating deteriorated.

Furthermore, when a saturated polyhydric alcohol was added to this material, the deterioration characteristics worsened due to heat treatment when it was placed in an iron container, which is a standard storage container for silver halide photosensitive materials that use fatty acid cellulose ester as a support. .

According to the Antioxidant Handbook (co-authored by Kenichi Saruwatari, Takashi Nishino, Yutaka Tabata, Showa, 51, 10.10, pp. 12-31, Daikaisha), antioxidants have the following functions: They can be classified into four types: absorbers, light stabilizers, metal deactivators, ozone deterioration inhibitors, etc.), radical chain inhibitors, peroxide decomposers (secondary antioxidants), and carrier agents. . According to this, among the above methods, hindered phenol is classified into ■, and phosphite ester compound and thioether are classified into ■.
Organic acids can be classified as ■.

In addition to the above methods, a method of applying ultraviolet absorbers and light stabilizers is known (Japanese Patent Application Laid-open No. 59-12703, No. 5).
However, since the present invention is based on the premise that deterioration occurs even in a dark room, such a method is clearly insufficient.

Of (2), metal deactivators have the function of chelating and inactivating metal catalysts, but have not been studied so far. However, it is known that iron as a metal catalyst, for example, transfers to fatty acid cellulose ester from a storage container and significantly accelerates deterioration (N, S, Al
1en etal, J. Photogr.

Sci, 36 194-198, 1988), we investigated this type of deterioration inhibitor that has the function of deactivating metals, and found that a remarkable deterioration prevention effect was observed when combined with the above-mentioned deterioration inhibitor. It's arrived.

"Problem to be solved by the invention" Literature (N, S, Allen etol, J, Photo
gr, Sci.

36.194-198.1988), cellulose acetate is an excellent product that is extremely resistant to deterioration when stored properly, but it is not sealed in a metal case. If it is stored under high temperature and high humidity, the degree of polymerization and acetylation will decrease due to hydrolysis.

An object of the present invention is to prevent cellulose acetate from deteriorating under harsh conditions such as being stored in a metal case or hermetically sealed at high temperature and high humidity.

SUMMARY OF THE INVENTION These objects of the present invention were achieved by adding a metal deactivator to cellulose acetate. Furthermore, by using a radical chain inhibitor and a peroxide decomposer in combination, cellulose acetate was able to be significantly prevented from deteriorating.

In the present invention, (A) peroxide decomposer is of the form (
A-1), (A-11), (A-111), and (B) radical chain inhibitor is a compound represented by -form (B-1), (B-11). and
(C) Metal deactivator has the general formula (C-■), (C-1
1), (C-111).

General formula (A-1) - Format (6-■) - Format (A-
I[1)H Rz+ Rs. -3Ih+ X-P-R,.

)1 Rho P RZZ General formula (B-1) General formula (B-n) H SI 42 General formula (C-1) General formula (C-11) R6゜-NHC-CNH-R&II 11 0 R4゜- CNHNIICR6 111 0 General formula (C-I[1) il General formula (A-1) to (C-111) where x represents a hydrogen atom, an alkali metal, or an alkaline earth metal. R
5° represents an alkyl group, an alkenyl group and an aryl group. R2゜, R111 and Rz□ may be the same or different, and each represents an alkyl group, an alkenyl group,
It represents an aryl group, an alkoxy group, an alkenoxy group, an aryloxy group, an alkylthio group, an alkenylthio group and an arylthio group.

R3° and R1 may be the same or different and represent an alkyl group, an alkenyl group and an aryl group, respectively. R4° represents an alkyl group. R41, R12 and Y may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkenoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, or an alkenyl group. thio group, arylthio group, hydroxy group, amino group which may have a substituent, carbamoyl group, sulfamoyl group,
Represents an alkoxycarbonyl group, an aryloxycarbonyl group, a halogen atom, a nitro group, a cyano group, an acyl group, and an acyloxy group. m represents an integer from 0 to 2.

R2° and R51 may be the same or different from each other,
Each represents an alkyl group, an alkenyl group, and an aryl group. R52 represents a hydrogen atom or a group defined as R5°. R6° and R1 may be the same or different and represent an alkyl group, an alkenyl group, an aryl group, and a heterocyclic group, respectively. Z represents the group defined for Y, and n represents an integer of 0 to 4. When m is 2, multiple Y
may be the same or different from each other, and similarly when n is 2 to 4, the plurality of Z's may be the same or different from each other. R2° and R3, R5° and Ro, and R6° and R5I may be bonded to each other to form a 5- to 7-membered ring.

- The substituents represented by formats (A-1) to (C-1ff) will be explained in more detail.

X represents a hydrogen atom, an alkali metal (for example, lithium, sodium, potassium), or an alkaline earth metal (for example, calcium, barium, magnesium). R1゜, Rz
o, R□, R2□, R3゜, R31, R4゜, R□, R
4□, Y, R,. ,R5,,R,. And the alkyl group defined for R1 is a straight chain, branched or cyclic alkyl group (
For example, methyl, ethyl, propyl, i-propyl, L-
butyl, cyclohexyl, t-hexyl, t-octyl, dodecyl, hexadecyl, octadecyl, benzyl)
represents RIG, RZO1R21, Rzz, R30,
R31, Ro, R4□, Y, R,. , Rsl, Rh.

The alkenyl group defined by
%R2□, R3゜, R31% R41, R4□, Y, R
s. , R51, R6° and R1 represent a benzene monocyclic or fused polycyclic aryl group (e.g. phenyl, naphthyl, anthranyl), R41, R4□, Y,
R.

The heterocyclic group defined as R1 and R1 is a 5- to 7-membered cyclic group containing at least one atom selected from nitrogen atom, sulfur atom, and oxygen atom as a ring constituent atom (e.g., furyl, pyrrolyl, imidazolyl, pyridyl, purinyl, chromanyl). , pyrrolidyl, morpholinyl).

R1° represents an alkyl group, an alkenyl group or an aryl group. R2゜, R1 and R2□ may be the same or different, and each represents an alkyl group, an alkenyl group, an aryl group, an alkoxy group (for example, methquine, ethoxy,
methoxyethoxy, octyloxy, hensyloxy,
cyclohexylthione, i-propoxy, tetradecyloxy, octadecyloxy), alkenoxy groups (e.g. vinyloxy, propenyloxine, cyclohexenyloxy, dodecenyloxy, octadecenyloxy),
Ori-ruoxy group (e.g. phenoxy, naphthoquine),
Alkylthio groups (e.g. methylthio, ethylthio, i-
propylthio, cyclohexylthio, benzylthio, octylthio, dodecylthio, hexadecylthio, octadecylthio), alkenylthio groups (e.g. vinylthio,
Allylthio, cyclohexenylthio, hexadecenylthio), and allylthio groups (eg, phenylthio, naphthylthio). R1° and R31 may be the same or different and represent an alkyl group, an alkenyl group, and an aryl group, respectively. R4° represents an alkyl group. R41, R4□ and Y may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkenyl group,
Aryl group, heterocyclic group, alkoxy group similar to R2゜, alkenoxy group, aryloxy group, alkylthio group, alkenylthio group, arylthio group, heterocyclic oxy group (e.g. imidazolidinyloxy, morpholinyloxy, tetrahydropyran) -3-yloxy, 1.3゜5
-triazin-2-yloxy), hydroxy group, amino group which may have a substituent (e.g. amino, alkylamino, arylamino, dialkylamino, acylamino, sulfonamide, ureido, urethane), carbamoyl group (e.g. N-methyl carbamoyl, N-phenylcarbamoyl, N,N-diethylcarbamoyl), sulfamoyl groups (e.g. N-ethylsulfamoyl, N-phenylsulfamoyl), alkoxycarbonyl groups (e.g. methoxycarbonyl, butoxycarbonyl, ncrohexyloxycarbonyl) , octyloxycarbonyl, hexyloxycarbonyl, octadecyloxycarbonyl), aryloxycarbonyl groups (e.g. phenyloxycarbonyl, naphthyloxycarbonyl), halogen atoms (e.g. fluorine atom, chlorine atom, bromine atom)
, nitro group, cyano group, acyl group (eg acetyl, hendiyl, naphthoyl), acyloxy group (eg acetyloxy, henzoyluoquine, naphthoyloxy). m represents an integer from 0 to 2. R1° and R5
I may be the same or different, and each represents an alkyl group, an alkenyl group, or an aryl group. Rsz represents a hydrogen atom and a group defined as R2°. R&O and R61 may be the same or different and represent an alkyl group, an alkenyl group, an aryl group and a heterocyclic group, respectively. Z represents the group defined for Y, and n is 0 to 4
represents an integer. When m is 2, the plurality of Y's may be the same or different from each other (Similarly, when n is 2 to 4, the plurality of Z's may be the same or different from each other.

R2゜ and R2゜R3゜ and Rff+, Rs. and R5I may combine with each other to form a 5- to 7-membered ring.

-a Among the compounds represented by the formula (A-11), it is preferable that all of R2° to R1z are selected from an alkyl group, an aryl group, an alkoxy group, and an aryloxy group. It is more preferable that R2゜ to R2□ are all selected from an alkyl group, an aryl group, and an aryloxy group. Among these, when an aryloxy group is present, a substituent is added to the ortho position of the Hensen ring of the aryloxy group. It is preferable to have one.

Further, when at least two of R2° to R2□ are aryloxy groups, it is preferable that the two aryloxy groups are bonded to each other at the ortho positions of the benzene rings, or to substituents at the ortho positions.

Among the compounds represented by the -form (B-1), preferred compounds can be represented by the following -forms (B-1-1) and (B-1-n).

-Form rule (B-1 ■) General formula (B-1-n) H H H 42 In the formula, R1゜' represents a tertiary alkyl group, and R4゜〃
and R4゜'l/ may be the same or different and each represents an alkyl group. L is single R43R4
4 represents -3--0--N--C-.

45 Here, R4ff represents a hydrogen atom, an alkyl group, or an aryl group. Raa and RAS may be the same or different and represent a hydrogen atom, an alkyl group, and an allyl group, respectively. R4□, R4□, Y and m have the same meaning as in general formula (B-1), and Y' has the same meaning as Y. m′
and m# have the same meaning as m.

Among the compounds represented by the general formula (B-It), a more preferable compound can be represented by the general formula (B-ff-1).

General formula (B-If-1) 1st A'' In the formula, A represents a nonmetallic atomic group necessary to form a 5- to 7-membered ring, and R52 has the same meaning as general formula (B-11). R53 to R5& may be the same or different and each represents an alkyl group.

Specific examples of compounds represented by general formulas (A-■) to (C-I[1) of the present invention are shown below, but the present invention is not limited thereto.

(A 1> 11 NaP C411Jn) 1 (A 2) ft NaP Cs1l+7(n) j (A 3) 11 NaP CIJzs(n) 1 (A 4) H LiP C+a11. (n) 1 (A 11) H (A 12) 11 (A 13) 11 (A 14) H (A 15) 11 (A 16) Pi0C1oHz+)s (A 6) (A 7) H (A 8 ) H (A 17) P i OC + Jz7): + (A 24) (A-35) (A-36) (A-37) (A-38) (A-39) (A-40) (A-41 ) S + CHzCHzC (hC+ 2Hzs) zS
+ CHzC1hCOtC+ Jz,)! S+CHz
CHzC (hczlhJz S + CHzCHzCOzC+ aLt) zH3 S +CHC) IzCOzC+5lht)z3Ht S +C112CH2CO□H)z S + CH2CH20CH2CH20 )1)2S+
oco! cl1goct+2co2oIOff(B-
1 canq(t) (B ■ 3) H (B ■ 4) 11 (B ■ 5) H (B ■ 6) 11 Js (B ■ 11) H H (B ■ 12) 11 CHzCLC(hc+++tl+t (B ■ 13) ) 11 (B ■ 7) (B ■ 8) (B ■ 9) (B ■ 10) (B ■ 15) (B ■ 16) H 0 ■ R H H (B ■ 21) (B ■ 22) C, 11° (B ■ 27) (B ■ 28) (B-1 29) t-C,H,+ (B ■ 23) 11 C3117(+) R (B ■ 24> C, 11.

(B ■ 25) 11 H aH9 4H9 (B +-30) (B 1-31) H (B-1 32) H H Cl1□OH C) I20H (B ■ 1) (n ■ 2) Cl1゜ Hs ShiH3 Shih Go (B ■ 8) (B ■ 6) H Cl1l+ , (t) Molecular weight 2500 or more (B ■ 7) C) IcO□C 3H1゜ Cll2C02CI:IH2F (B ■ 10) L CIICO□C+Jz.

CIl□CO□C, ffl+□7 (B ■ 11) C11゜ (B ■ 17) (B ■ 18) (B ■ 19) (B ■ 20) (B ■ 21) H3 C1(.

(B ■ 12) (B-It 13) N(C4L)z (B ■ 14) N + CaH2)* (B ■ 22) (B ■ 23) (C ■) OC, Hl C2II 5 (C 2) u Shizus U υ ShiJs (C 3> OCHff (C 7) (C 4) H Ca1lq (L) 11 (C 8) 0I (■ (C 9) 110 CCII□CI+, -C 111 0 NHN) I -C -C11□C1,GO,HI3 (C-10) HOCIIzCL Nll CCNHCHzCHz
OH1110 Since most of these compounds are commercially available, they can be easily obtained.

The present invention provides compounds (C) or (A) and (B) and (C
), but is it a method of adding this to cellulose acetate when obtaining a film molded product? '8 A method of adding during the liquid film forming process is mentioned.

Film forming is a method of producing a film by casting a dope obtained by adding cellulose acetate (into a medium) onto a support, and (1) containing cellulose acetate in the dope. Solid content is 18-35
(2)) The volume is 65-82% by weight, and the 7-vehicle composition is (2-1) 75-87% by weight of a good solvent such as methylene chloride (2-2) Cellulose triacetate Poor solvent 0-25
It is preferable to use a mixed solvent consisting of % by weight.

The acetyl group of cellulose acetate used in the present invention is 3
A range of 7 to 62.5% is preferred.

It is preferable to use a tope with a high degree of cellulose acetate as the dope, and the concentration of the sum of cellulose triacetate and other components that become solid after drying is 18% by weight or more, preferably 20 to 35% by weight.

Other components that become solid after drying include cellulose derivatives such as cellulose acetate propionate and cellulose acetate butyrate, plasticizers such as triphenyl phosphate, and various additives that may be added as necessary.

(C) or (A) and CB) and (C) can be added as one type of these additives.

As the solvent, a good solvent for cellulose triacetate such as methylene chloride is used. Furthermore, the mixed solvent of the present invention can contain a poor solvent for cellulose triacetate, such as alcohols having 1 to 4 carbon atoms and cyclohexane. These may be used alone or in combination of two or more. In particular, as described below, it is desirable to contain an alcohol such as n-butanol or a poor solvent such as cyclohexane in order to promote cooling gelation of the dope.

As a preferable solvent composition, methylene chloride is 75%
-87% by weight, and 0-25% by weight of poor solvent. The concentration of cellulose triacetate and the composition of the solvent in No. 2 make it easy to produce a dope by the method described below. It is also preferable to cool the support to a temperature of 10° C. or lower because it causes gelation of the dope and facilitates recognition. In addition, at this time, it is necessary to make the gelling temperature of the dope, which depends on the concentration of cellulose triacetate and the solvent composition, higher than the support temperature. Such a dope is produced, for example, by putting cellulose triacetate and the above-mentioned solvent in a pressurized container, sealing it, heating it under pressure to a temperature above the boiling point of the solvent at normal pressure and within a range where the solvent does not boil, and stirring. obtained by

Cellulose triacetate, a solvent, and other additives added as necessary may be roughly mixed in advance and then placed in a pressurized container, or may be charged separately.

The type of pressurized container does not matter, as long as it can withstand a predetermined pressure. This pressurized container needs to be able to be pressurized and also stirred.

Pressurization may be carried out by injecting an inert gas such as nitrogen gas, or may be carried out only by increasing the vapor pressure of the solvent by heating.

In addition, it is also possible to utilize the reduction in gas phase volume within the container by pressurizing the pressurized container with some or all of the cellulose triacetate, solvent, and other additives after the container is sealed.

Preferably, the heating is performed from the outside, and for example, a jacket type one is suitable.

In addition, it is also possible to provide heating by providing an external plate heater or the like and connecting it with piping for circulation.

The stirring blade is preferably long enough to reach near the container wall, and it is preferable to provide a scraping blade at the end to renew the liquid film on the container wall.

In addition, other gauges such as pressure gauges and thermometers should be installed as appropriate in the pressurized container.

The above raw materials are placed in a pressurized container and heated under pressure.

The heating temperature is a temperature above the boiling point of the solvent and within a range where the solvent does not boil. This temperature is preferably 60°C or higher, particularly preferably about 80 to 110°C. The pressure is determined so that the solvent does not boil at this set temperature.

After melting, it is cooled and then taken out from the container, or taken out from the container with a pump or the like, cooled with a heat exchanger or the like, and then used for film formation.

In this dissolution method, by applying pressure, it is possible to heat the material above the boiling point at normal pressure, and boiling is suppressed to prevent the formation of an overconcentrated state, thereby preventing gel formation. Heating increases solubility and melting rate, making it possible to completely melt in a short time.

The dope casting method may be either a band casting method or a drum casting method. When cooling the casting part, any method using a refrigerant or cold air, a method using a heat pipe, etc. can be used, as disclosed in Japanese Patent Laid-Open No. 62-37113.

The cooling temperature is such that the surface temperature of the support is 10°C or less, preferably 5°C.
Keep the temperature below ℃.

Although it is not necessary to use drying air, it may be used as long as it does not increase the surface temperature of the support.

After being peeled off after casting, the film is dried while applying a certain tension in the direction of the film, as disclosed in JP-A No. 62-115035, to produce a film with a predetermined amount of residual solvent. preferable.

(A) peroxide decomposer, (B) radical chain inhibitor, and (C) metal deactivator are cellulose acetate 100
It is preferable to mix 0.05 to 2.0 parts by weight with respect to each part by weight. More preferably, each is from 0.1 to
It is preferable to add 1.0 parts by weight.

In the present invention, if the amount of (A), (B), or (C) added is less than this, the deterioration prevention effect will not be sufficiently exhibited, and as the amount added increases, the deterioration prevention effect will gradually increase, but if the amount added is If the amount exceeds this amount, not only will the deterioration prevention effect decrease, but especially (C) will exceed the compatibility limit and become cloudy and bleed onto the surface of the film-formed product, so it should not be added in an amount greater than the above amount. is not appropriate.

Although the method of adding and blending raw materials in the present invention has been described above, the present invention is not limited thereby.

"Effects of the Invention" According to the present invention, cellulose acetate can be obtained that exhibits a small decrease in viscosity, that is, a decrease in the degree of polymerization, even under severe conditions such as being sealed in a metal case or under high temperature and high humidity. That is, it is possible to obtain cellulose acetate having excellent weather resistance, heat and humidity resistance, heat resistance and storage stability.

"Example" Deterioration inhibitors (A) and/or (B) or and (C) shown in Table 1 were added to prepare the following compositions.

Cellulose triacetate 100 parts by weight (triphenyl phosphate) 19 parts by weight (A) Peroxide decomposer (Table 1) 0.25 parts by weight (or 0) (B) Radical chain inhibitor (Table 1) 0.25 parts by weight Part (or 0) (C) Metal deactivator (Table 1) 0.50 parts by weight Methylene chloride 270 parts by weight Butanol 7 parts by weight Methanol
70 parts by weight of the above-mentioned precipitate was placed in a closed container and stirred under pressure while maintaining the temperature at 80° C. to completely dissolve it.

The dope was then filtered, cooled and cast onto a rotating jacketed drum having a diameter of 30c11 while being maintained at 25°C. The drum is made of SB material, which is required to have heat conductivity, corrosion resistance, and flatness, and is plated with a Ni layer of about 50 μm, and then hard chrome plated twice with a thickness of about 40 μm.
A super-mirror-polished product with a polishing diameter of 0.01 to 0.053 was used. At this time, cold water is passed through the jacket of the drum to maintain the surface temperature at 0°C. Casting speed is 3m
/min, and the film was peeled off using a peeling roll at a position rotated 270 degrees in the casting direction from the casting position.
The base is drawn off at a speed of 5 m/min and cast by 5% in the casting direction. The stripped base is fixed on both sides and 70
It was dried with hot air at 0.degree. C. to obtain a film with a thickness of 140 .mu.m.

In addition, as a comparative example, compounds (A) (B) (
It was prepared with the composition excluding C), that is, the following composition.

Cellulose acetate 100 parts by weight Triphenyl phosphate) 2 omt parts Methylene chloride 270 parts by weight Butanol
7 parts by weight methanol
A film having a thickness of 140 μm was obtained as a comparative example by forming a film using 70 parts by weight of the above dope in the same manner as above.

Next, a method for evaluating the deterioration prevention effect will be explained.

1.5 g of the sample and 0.2 g of iron wire were placed in a 15 jd glass container, and the humidity was controlled for 1 hour at 90°C and 100% relative humidity.The container was then sealed and heated at 90°C and 100% relative humidity. Heat treatment for an hour. After rinsing the obtained sample three times with methyl alcohol and removing the plasticizer, it was dried at 120°C for 2 hours to absolute dryness, and the relative viscosity was determined according to ASTM D871.
Measure according to the viscosity method shown in .

Next, viscosity measurement will be explained in detail.

Dissolve 1 g of an absolutely dry sample in 100 g of a mixed solvent of 900 parts of methylene chloride and 100 parts of methanol, and place this in an Ubbelohde viscometer (with a flow time of about 90 seconds for water). The flow time was measured. The ratio of the flow time of the sample solution to the flow time measured with only the mixed solvent was taken, and this was calculated as the relative viscosity.

The obtained relative viscosity is expressed as a percentage ratio to the relative viscosity of the sample before thermal treatment, that is, a viscosity decrease, and is used as an index of a decrease in the degree of polymerization, that is, deterioration.

The intrinsic viscosity of these samples was measured, and the viscosity reduction was calculated from the ratio with the sample before heat treatment. The above results are shown in Table ■.

The sample without the deterioration prevention method shown in Comparative Example 11 showed a large viscosity drop of 9%, but when a metal deactivator was added, the viscosity drop was clearly improved as shown in Examples 1 to 3. Ru. Further, by using a peroxide decomposer and a radical chain inhibitor in combination, as shown in Examples 4 to 10, the decrease in viscosity is significantly improved and is almost no longer observed.

Here, the fluctuation range of viscosity measurement is ±0.2% range, and 1%
The difference is extremely significant. Further, a decrease in viscosity means a decrease in the degree of polymerization, but a decrease in the degree of acetylation also occurs at the same time. Therefore, the solubility of the sample deteriorates, and the apparent decrease in viscosity due to gelation becomes smaller. That is, comparative example Mai
The viscosity difference between the viscosity reduction of 9% and the example is 1 to 2
% difference is considered to be a large difference6 4. Subject of amendment "Detailed Description of the Invention" column of the specification

Claims (2)

[Claims] (1) A method for preventing deterioration of cellulose acetate, which comprises adding a metal deactivator to cellulose acetate. (2) A method for preventing deterioration of cellulose acetate, which comprises adding the following (A), (B), and (C) to cellulose acetate. (A) Peroxide decomposer (B) Radical chain inhibitor (C) Metal deactivator