JPH09241571A - Uv absorbing film and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film which can be mass produced on a commercial scale and possesses a heat sealing property and an ecological ultraviolet absorbing property to provide a process for preparing the same. SOLUTION: This film comprises benzylated cellulose or benzylated lignocellulose soluble in an org. solvent. The process for preparing the above film comprises the steps of: making a dissolving pulp or a wood fiber alkaline; reacting the pulp or fiber with benzyl chloride to prepare benzylated cellulose or benzylated lignocellulose; dissolving the benzylated cellulose or benzylated lignocellulose in an org. solvent; and solidifying the solution into a thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film that absorbs ultraviolet rays and a method for producing the same.

[0002]

2. Description of the Related Art Since the discovery of an ozone hole in the ozone layer above Antarctica in 1985, various techniques for avoiding the adverse effects of ultraviolet rays have been developed. An example is a UV-reflecting material mixed with titanium oxide powder, and the applicant previously described in JP-A-4-33986 that lignocellulose as a UV-absorbing material utilizing a natural polymer material having biodegradability. Proposed a membrane.

The present invention is formed by solidifying a film of a mutual solution of lignin and cellulose. Specifically, the wood chips are vapor-deposited and blasted to be fibrous, and after extraction with water and alkali or organic acid to obtain lignocellulosic fibers,
For example, this is made into a viscose purified by a viscose method, and a functional film having an ultraviolet absorbing property is obtained through a conventional continuous production process of cellophane.

[0004]

However, the lignocellulosic membrane described above has a low efficiency of dissolving the cellulose and thus has a low efficiency of producing the membrane. In addition, the lignocellulosic membrane is difficult to apply to the existing cellophane production process during production, and is difficult to industrialize. Further, since the film itself does not have a heat-sealing property, processing and application range are limited. In view of these problems of the conventional technology, an object of the present invention is to provide a coating that can be industrially mass-produced, has a heat-sealing property, and has an ecological ultraviolet absorbing property, and a manufacturing method thereof. is there.

[0005]

The present invention is characterized in that it has the following constitution in order to achieve the above object. That is, the coating film of the present invention is composed of benzylated cellulose or benzylated lignocellulose soluble in an organic solvent. Further, the method of the present invention, alkalizing the dissolving pulp or wood fiber, to react with benzyl chloride to obtain benzylated cellulose or benzylated lignocellulose, after dissolving the benzylated cellulose or benzylated lignocellulose in an organic solvent , To form a film by solidifying into a thin film.

Benzylated cellulose is produced by alkalizing cellulose with a concentrated aqueous solution of sodium hydroxide and reacting the alkali cellulose with benzyl chloride. 90 ° C
It has a softening point and a melting point at ~ 150 ° C, and has desirable properties as a heat seal or hot melt adhesive. Although the solubility in an organic solvent varies depending on the degree of substitution of benzyl groups and the degree of polymerization of cellulose, for example, the synthesis of benzylated cellulose which is soluble in tetrahydrofuran is relatively easy.

Benzylated lignocellulose is produced by applying the above-mentioned method for producing benzylated cellulose to wood fibers (lignocellulose). Cellulose in wood fibers is benzylated, and hemicellulose and lignin are also benzylated. Since benzylated hemicellulose and lignin act as plasticizers, they have a lower softening point and melting point than benzylated cellulose. The benzylated wood fiber tends to have a lighter coloration derived from lignin. In addition to lignin, the benzyl group also absorbs UV light, so the UV wavelength and near UV wavelength are completely cut, and a UV absorption film with a slightly yellowish, nearly ideal UV absorption film with a good rise in transmittance over the visible wavelength can be obtained. .

The film is obtained by solidifying on the surface of a plate material such as glass, but it may be solidified on the surface of a film such as cellophane. For example, by coating cellophane with the above-mentioned thin film, it is possible not only to block ultraviolet rays but also to impart heat sealability, moisture resistance and water repellent property. Conventional cellophane may be coated with a moisture-proof resin (a vinyl chloride-based resin or a vinylidene chloride-based resin), but as compared with these, the present invention has an easily disintegrating property in a natural environment. In addition, since the moisture-proof resin generally has a lower calorific value than the petroleum-based synthetic film, it tends to damage the furnace during incineration. In particular, since moisture-proof resins such as vinyl chloride and vinylidene chloride contain chlorine, they not only damage the incinerator but also cause air pollution. Benzylated cellulose is
Purification to remove benzyl chloride sufficiently avoids these problems. Furthermore, since hydroxyl groups remain in both benzylated cellulose and benzylated lignocellulose, the adhesive force to the surface of the film or plate material such as cellophane is strong.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the present invention will be described below.

Example 1 30 parts by weight of dissolving pulp (99% or more of α-cellulose) was alkalized into 150 parts by weight of 40 (w / w)% sodium hydroxide at room temperature in a nitrogen stream for 1 hour. To this, 200 parts by weight of benzyl chloride was added, and the temperature was raised to 105 ° C. in about 1 hour. This was kept at 105 ° C. for 6 hours for benzylation, and the benzylated product was washed successively with methanol and water to obtain 60 parts by weight of benzylated cellulose. Next, 10 parts by weight of this benzylated cellulose was dissolved in 500 parts by weight of tetrahydrofuran, the insoluble part was filtered off, and the filtrate was concentrated to 100 parts by weight with a rotary evaporator. The concentrate was coated on cellophane (10 g of concentrate / 30 × 30 cm 2 of cellophane), and the tetrahydrofuran solvent was evaporated, whereby a film of benzyl cellulose was formed on cellophane.

Example 2 Hinoki chips were cooked at 220 ° C. for 5 minutes, the crushed sample was extracted with water and extracted with 70% acetone. 30 parts by weight of residual fiber (lignin content 32.9%) was added to 40 (w / w). w) Alkalinized in 250 parts by weight of% sodium hydroxide at room temperature in a nitrogen stream for 1 hour. To this, 300 parts by weight of benzyl chloride was added, and the temperature was raised to 105 ° C. in about 1 hour. 6 hours 1
After the mixture was maintained at 05 ° C. to be benzylated, the benzylated product was washed with methanol and water successively to obtain 55 parts by weight of hinoki steamed and exploded residue fiber benzylated product. Next, 10 parts by weight of the benzylated product of the cypress cooking and explosion residue fiber obtained by the above operation was dissolved in 500 parts by weight of tetrahydrofuran, and the insoluble portion was removed by filtration, and the filtrate was concentrated to 50 parts by weight with a rotary evaporator.
The cellophane was coated with the concentrate (concentrate 10
g / cellophane 30 × 30 cm ² ), when the tetrahydrofuran solvent was evaporated, cypress was steamed on cellophane.
A benzylated coating of the blast residue fibers was formed.

Example 3 Beech chips were steam-cooked at 20 kg / cm 2 for 6 minutes and the crushed sample was extracted with water and extracted with 1% aqueous sodium hydroxide solution. 20 parts by weight of residual fiber (lignin content 15.3%) was added to 40 parts by weight.
100 parts by weight of (w / w)% sodium hydroxide was alkalized at room temperature in a nitrogen stream for 1 hour. To this, 100 parts by weight of benzyl chloride was added, and the mixture was kept at 105 ° C. for 4 hours for benzylation, and the benzylated product was washed successively with methanol and water to give 34 parts by weight of beech-cooking / explosion residue fiber benzylation product. Obtained. Next, 10 parts by weight of the beech-cooked / explosion residue fiber benzylated product obtained by the above operation was dissolved in 500 parts by weight of tetrahydrofuran, and the filtrate obtained by removing insoluble matter by filtration was concentrated to 800 parts by weight with a rotary evaporator. The concentrated solution was coated on cellophane (concentrated solution 10 g / cellophane 30 × 30 cm ² ) and the tetrahydrofuran solvent was evaporated. As a result, a film of the benzylated product of the beech-boiled / explosion residue fiber was formed on the cellophane.

Table 1 shows the anti-fading performance due to ultraviolet rays of the plant-dyed textiles produced by the ultraviolet-absorbing coatings obtained in Examples 1 to 3. Place the sample film on the fabric dyed with Akane and expose it to ultraviolet light with a wavelength of 253 nm.
The presence or absence of discoloration after long-time irradiation was evaluated by visual angle. As a control, the fabric was directly exposed to UV light for the same time without placing the film, the commercial cellophane was placed on the fabric for UV light irradiation for the same time, and the fabric covered with Saran wrap was exposed to UV light. What was irradiated for the same time was used.

[0014]

[Table 1]

As is clear from this table, all the fabrics in the control group were completely decolorized, but Examples 1 to 3 according to the present invention were used.
No bleaching of the woven fabric was observed in any of the films coated with the above, which shows the ultraviolet absorbing ability of these films.

[0016]

As described above, according to the present invention, since it is made of benzylated cellulose or benzylated lignocellulose which is soluble in an organic solvent, it has a low softening point and a low melting point, so that a thin film is provided with heat sealability. It can be given and its application range can be expanded. Also, the method of the present invention,
Alkalizing pulp or wood fiber for dissolution and reacting with benzyl chloride to obtain benzylated cellulose or benzylated lignocellulose, which is dissolved in an organic solvent and then solidified into a thin film. Since it is a film, industrial mass production can be performed relatively easily. Furthermore, since the thin film according to the present invention is easily disintegrated in a natural environment, it is possible to provide a coating film having ecological UV absorption. In addition, this coating has a lower calorific value than moisture-proof resins and does not contain chlorine, so it does not damage the furnace or generate chlorine gas when incinerated, and it is easy and safe to incinerate. It is possible.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 97/02 LSW C08L 97/02 LSW C09D 5/32 PRB C09D 5/32 PRB C09K 3/00 104 C09K 3/00 104Z

Claims (7)

[Claims] 1. An ultraviolet-absorbing film comprising benzylated cellulose or benzylated lignocellulose soluble in an organic solvent. 2. The ultraviolet absorbing film according to claim 1, wherein the organic solvent is tetrahydrofuran. 3. A solubilized pulp or wood fiber is alkalized and reacted with benzyl chloride to obtain benzylated cellulose or benzylated lignocellulose. The benzylated cellulose or benzylated lignocellulose is dissolved in an organic solvent, and then a thin film is formed. A method for producing an ultraviolet-absorbing coating, which comprises solidifying into a shape. 4. The method for producing an ultraviolet absorbing coating according to claim 3, wherein the thin film is solidified on the surface of the film. 5. The method for producing an ultraviolet absorbing coating according to claim 3, wherein the coating is solidified on the surface of a plate material such as glass. 6. The method for producing an ultraviolet absorbing film according to claim 3, wherein the organic solvent is tetrahydrofuran. 7. The method for producing an ultraviolet absorbing film according to claim 4, wherein the film is cellophane.