JPH1160761A - Saponification treatment of cellulose-based plastic molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To subject a cellulose-based plastic molding product to saponification treatment in a way to allow partial saponification, not damaging luster, smoothness, anti-fogging properties, etc., maintaining an excellent operation environment and workability, not deforming a molding product after treatment, by using a specific alkali alcohol aqueous solution. SOLUTION: A cellulose-based plastic molding product (a molding product such as cellulose acetate plastic such as swimming goggles, ski goggles, various light screening tools, a mirror, etc.), is made into a swollen state by using an alkali alcohol aqueous solution (one having 0.01-10 normal alkali concentration and containing 0.1-50 wt.% of an alcohol) consisting essentially of an alkali compound such as potassium hydroxide or sodium hydroxide and an ether bond-containing alcohol [one preferably shown by the formula HO-(-R1 -O-)n -R2 ((n) is 1-3; R1 is a 1-3C alkylene; R2 is H or a 1-4C alkyl) such as preferably 2-methoxyethanol or the like] and subiected to saponification treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for saponifying a fibrous plastic molded article, and more particularly, to an excellent anti-fog method applied to underwater glasses, ski goggles, various light-shielding protective devices, mirrors and the like. The present invention relates to a method for saponifying a fibrous plastic molded article having a property.

[0002]

2. Description of the Related Art Cellulosic plastic moldings are excellent in transparency, toughness at low temperature, gloss, weather resistance, and processing characteristics. Since it can be obtained, it is commercialized and used for underwater glasses, goggles and the like.

Conventionally, as a method for improving the antifogging property by saponifying the surface of a fibrous plastic molded article,
A method using sodium hydroxide or potassium hydroxide is known. Also, to shorten the saponification time,
Swelling action methyl alcohol, ethyl alcohol,
It has been proposed to add a small amount of alcohol such as isopropyl alcohol (Japanese Patent Publication No. 60-56739). By the way, by this treatment method, the surface of the fibrous plastic molded article can be provided with anti-fogging properties, but alcohol such as methyl alcohol has high volatility, so it is difficult to control the concentration of the saponification treatment liquid, and However, there is a problem that the working environment is adversely affected.

Further, for example, when it is necessary to saponify only one side or a part of a plate-shaped molded product, hydrolysis of an ester, generation of hydrogen bonds, elution of a plasticizer, etc. occur on the treated surface. Since the mechanical balance with the untreated surface is lost due to the shrinkage of the treated surface, the plate-like molded product after the saponification treatment is warped or deformed. Therefore, at present, there is no processing method capable of saponifying only one side or a part of the processed plate-like molded product without deformation.

[0005]

SUMMARY OF THE INVENTION The present invention can maintain a clean working environment and good workability without impairing gloss, smoothness, anti-fog properties, etc. It is an object of the present invention to provide a method for saponifying a fibrous plastic molded article which can be saponified on one side or only a part without being deformed.

[0006]

According to the present invention, a fibrous plastic molded product is saponified by using an aqueous alkaline alcohol solution mainly composed of an alkaline compound and an alcohol having an ether bond. This is a method for saponifying a plastic molded product. Here, the alkaline compound is preferably potassium hydroxide and / or sodium hydroxide. Further, the alcohol having an ether bond preferably has a general structural formula represented by the following formula (1). HO-(-R ₁ -O-) _n -R ₂ (1) (where n is an integer of 1 to 3, and R ₁ has 1 to ₁ carbon atoms)
And R ₂ represents a group selected from the group consisting of hydrogen, methyl, ethyl, propyl and butyl. )

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a fibrous plastic molded product is subjected to a saponification treatment in a swollen state using a specific alkaline alcohol aqueous solution.
By sufficiently washing with an acidic aqueous solution or water and drying, a molded article excellent in gloss, smoothness, anti-fogging property and the like can be easily obtained.

Examples of the fibrous plastic molded product used in the present invention include molded products such as cellulose acetate plastic, cellulose triacetate plastic, cellulose acetate propionate plastic, and cellulose acetate butyrate plastic. , Underwater glasses, ski goggles, various light-shielding protective gears, mirrors and the like.

The aqueous alkaline alcohol solution used in the present invention is a mixture of an alkaline aqueous solution and an alcohol having an ether bond. This mixture has an alkali concentration in the range of 0.01 to 10 N and contains 0.1 to 50% by weight of alcohol.

Here, as the alkaline compound used in the alkaline alcohol aqueous solution, sodium hydroxide and / or potassium hydroxide are preferable, and the alkali concentration is suitably in the range of 0.01 normal to 10 normal as described above. It is. When the alkali concentration is low, the saponification treatment takes a long time, and the molded product may be deformed by long-term immersion. On the other hand, if the alkali concentration is too high,
A saponification reaction may occur rapidly, causing whitening of the surface and cracking.

As described above, the alcohol having an ether bond used in the present invention has the general structural formula represented by the following formula (1). HO-(-R ₁ -O-) _n -R ₂ (1) (where n is an integer of 1 to 3, and R ₁ has 1 to ₁ carbon atoms)
And R ₂ represents a group selected from the group consisting of hydrogen, methyl, propyl and butyl. )

Specific examples thereof include 2-methoxyethanol, 2-ethoxyethanol, 2,2-dimethoxyethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, and triethylene glycol monomethyl ether. And the like. Among alcohols having an ether bond, it is preferable to use dielene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether in view of gloss, smoothness, workability, economy, and the like. The alcohol having the above ether bond is
One type may be used alone, or two or more types may be used in combination.

Here, the alcohol has an effect of promoting swelling of the molded product. Lower alkyl alcohols, such as methyl alcohol, ethyl alcohol and isopropyl alcohol, mix well with water and have a swelling effect, but have the disadvantage of high volatility. On the other hand, if the carbon chain of the alcohol is long, it becomes difficult to dissolve in water, so that an alcohol aqueous solution cannot be obtained.

[0014] However, the alcohol containing an ether bond described above has a solubility in water even if the carbon chain is somewhat longer, and behaves significantly different from a higher alcohol. First, because of its high molecular weight, it is much less volatile than lower alkyl alcohols. Furthermore, according to the study of the present inventors, when it is necessary to saponify only one side or a part of a molded product, it plays a large role in preventing the molded product after saponification from warping or deforming. I have. That is, the deformation of the molded product after the saponification treatment is, as described above,
Elution of a decomposition product due to the hydrolysis reaction of the ester on the treated surface, elution of a plasticizer, and the like occur, and the mechanical balance with the untreated surface is lost.

Alcohol containing an ether bond has the same plasticizing effect as a plasticizer, and, because of its high molecular weight, is not easily eluted even when washed with water or the like. Therefore, alcohol containing an ether bond can suppress the mechanical imbalance with the untreated surface as a result of simultaneously compensating for the loss of the decomposed product and the plasticizer eluted from the treated surface and the plasticizing effect and as a result. It became.

As described above, the alcohol concentration is usually 0.1 to 50% by weight, preferably 0.5 to 50% by weight.
-10% by weight. If it is less than 0.1% by weight, the rate of swelling saponification is low, and concentration control is difficult due to absorption into molded products. On the other hand, if it exceeds 50% by weight, whitening of the treated surface is likely to occur.

[0017] The saponification temperature is preferably in the range of 10 to 60 ° C. If the temperature is lower than 10 ° C., the saponification rate of the surface of the molded product is slow, while if it is higher than 60 ° C., the molded product may be deformed in a sheet form. The saponification reaction time is in the range of 10 seconds to 24 hours, preferably 3 hours.
0 seconds to 2 hours. If the time is less than 10 seconds, the surface of the molded product does not swell sufficiently, and the saponification reaction does not sufficiently proceed. Meanwhile, 2
If it exceeds 4 hours, the gloss and smoothness of the surface may be impaired.

In the present invention, a surfactant may be added to the aqueous alkaline alcohol solution in order to smoothly carry out the saponification treatment.

[0019]

The present invention will be described below in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The compositions in Examples and Comparative Examples are parts by weight unless otherwise specified. Examples 1 to 12, Comparative Examples 1 to 6

A pellet of cellulose acetate propionate [307E0 manufactured by Eastman Kodak Company]
9 "] is extruded, and a test piece (100 mm × 10
0 mm × 0.5 mm).

The test piece of the formed product was immersed in a saponification solution shown in Table 1 and treated under the same processing conditions as shown in Table 1. In addition, when performing saponification treatment only on one side, a masking film was stuck on one side of a molded product test piece, and saponification treatment similar to the double-sided treatment was performed. The test specimen of the molded product was taken out of the saponification treatment solution, sufficiently washed with water or a 5% hydrochloric acid aqueous solution, and dried naturally or with hot air (40 ° C., 2 hours) to obtain a treated test specimen of the molded product. For each test piece, the physical properties of the molded product were measured. Table 2 shows the results.

Evaluation Method The following test items were measured in a test room at a temperature of 25 ° C. and a humidity of 65%. After standing 1 hour the breath test room temperature 25 ° C., 65% humidity environment,
Those which did not produce cloudiness due to exhalation were regarded as passed. (Pass; o) 40 ° C steam test A test piece was placed 5 cm directly above a 40 ° C hot water bath, and the occurrence of fogging was visually observed. Those which did not produce fogging even after 3 minutes or more passed were judged as acceptable. (Pass; ○, cloudy appearance; ×)

[0023] After immersing the test piece in a container containing the wetting test room temperature tap water for 30 minutes, taken out, the existence of repelling water droplets of treated surface was observed with the naked eye. Those which did not repel water droplets were accepted. (Pass; ○, Partially repelled; △) 5 ° C cloudiness test A test piece left standing in a refrigerator at 5 ± 2 ° C for 30 minutes in an atmosphere at room temperature of 25 ° C and humidity of 65% was taken out. The occurrence of fogging was visually observed. Those without fogging were judged as acceptable. (Pass; 、, clouding occurred; ×) Deformation warpage The molded product after the saponification treatment was placed on a horizontal plate, and deformation warpage was observed with the naked eye. Those without deformation warpage were accepted.
(Pass; ○, with warpage; ×)

[0024]

[Table 1]

In Table 1, the types of alcohol used are as follows. A: diethylene glycol monoethyl ether B: diethylene glycol monobutyl ether C: methyl alcohol D: ethyl alcohol

[0026]

[Table 2]

[0027]

The method for saponifying a fibrous plastic molded article of the present invention has the following features. Since an alcohol having an ether bond having a low volatility is used as the saponification treatment liquid, the adverse effect on the environment is substantially reduced, and a clean working environment and good workability can be maintained. The saponification treatment does not cause deterioration in physical properties such as gloss, smoothness and anti-fogging property of the surface of the molded product. The saponification treatment can be performed not only on both sides but also one side or a part of the molded product, and the molded product after the treatment does not warp or deform. In spite of the low alcohol concentration, a molded article having a good antifogging property in a short time can be obtained at low cost.

Claims (3)

[Claims] The method according to claim 1] Cellulose plastic moldings, saponification of cellulose-based plastics moldings, characterized in that saponification with an alkaline alcohol aqueous solution containing as a main component an alcohol having an alkali compound and an ether bond Method. 2. The method according to claim 1, wherein the alkaline compound is sodium hydroxide and / or potassium hydroxide. 3. The method for saponifying a fibrous plastic molded product according to claim 1, wherein the alcohol having an ether bond has a general structural formula represented by the following formula (1). HO-(-R ₁ -O-) _n -R ₂ (1) (where n is an integer of 1 to 3, and R ₁ has 1 to ₁ carbon atoms)
And R ₂ represents a group selected from the group consisting of hydrogen, methyl, ethyl, propyl and butyl. )