JP2000327798A - Base film for marking film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent base film for a marking film not having a problem such as volatilization, migration or the like of a plasticizer in the case of adding the plasticizer and utilizing a characteristic of a cellulose ester. SOLUTION: This base film for a marking film comprises a resin containing a fatty acid cellulose ester derivative obtained by ring-opening graft polymerization of a fatty acid cellulose ester having a hydroxy group with cyclic esters as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a base film for a marking film using a resin containing a specific cellulose derivative as a main component. More specifically, the present invention relates to a base film for a marking film comprising a resin having a fatty acid cellulose ester derivative obtained by ring-opening graft polymerization of a cyclic ester as a main component.

[0002]

2. Description of the Related Art A marking film is a base film for a film such as a large outdoor advertisement, a road sign, a street sign, a company name, etc., as well as a pattern for an emblem to be attached to the surface of clothing, daily necessities, toys and the like. Printing, thermal transfer of ink layer, etc., adhesive layer on the other side, refers to a film to be attached to the wall of transportation vehicles, buildings, utility poles, etc. Instead of painting individually, just stick it It is attracting attention as a construction that can be completed efficiently. Although some polyester films and polyurethane films have been conventionally used as the base film for the marking film, there are some films such as a polyester film and a polyurethane film. Easy to wear, easy to attach a film with a curl to a flat surface, waist of the film)
From the viewpoint of cost, a film made of a vinyl chloride resin is typical. A vinyl chloride resin is excellent in various points such as physical properties, weather resistance, film moldability, and printability, and has been preferably used as a base film material for a marking film.

As the vinyl chloride resin as the representative example, those having a polymerization degree of preferably 300 to 2,000, more preferably 600 to 1500 are used, and a polyvinyl chloride resin homopolymer or a vinyl chloride monomer and an olefin are used. System, diene system, vinyl halide system, (meth) acrylate ester system, vinyl ester system, vinyl ether system,
Resins related to copolymerization with various monomers such as styrenes are exemplified.

[0004] Incidentally, as an example of a marking film and its mode of use, a plastisol-cast vinyl chloride film of usually about 50 µm is used as a base film for a marking film, and a desired pattern such as a durable pattern is printed on one surface thereof. If necessary, it is further overprinted with clear ink to impart high durability, and an acrylic adhesive or the like is applied to a thickness of about 30 μm on the other surface, and is backed with a release film as necessary, Wound in a roll as a marking film. A cutting mark is formed by hand cutting, computer machine cutting, uncut cutting, or the like into a specified shape before the above-mentioned bonding work, and the release film is removed at a construction site to perform a bonding work on a vehicle body surface or the like.

[0005] By the way, it has been reported that the above-mentioned vinyl chloride resin most preferably used in the past has a high possibility of generating harmful substances such as dioxin at the time of incineration and disposal. As a result, as a substitute resin material, Research is ongoing. As one of the alternative resins, cellulose ester which satisfies various required characteristics such as toughness, glossiness, transparency, oil resistance, and good weather resistance, such as cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Derivatives have begun to attract attention as resins for marking films, but if they are to be heated and melted alone, coloring and decomposition are likely to occur simultaneously,
Dissolving the above cellulose derivative using various solvents, kneading, pressing, molding to obtain a sheet, even if applying the so-called block method, good thermal fluidity without the addition of a plasticizer,
A resin having plasticity cannot be obtained. in this case,
Examples of the plasticizer include conventionally known phthalic acid esters (eg, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, ethyl phthalyl ethyl glycolate, etc.) and trimellitic acid esters (eg, trimethyl trimellitate, triethyl trimellitate, For example, tri-2-ethylhexyl azelate), orthophosphate (eg, tributyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate), ricinoleate (eg, methyl acetyl ricinolate) and the like are used.

However, cellulose esters containing these plasticizers have a problem that the softening temperature tends to be lowered more than necessary. Cellulose derivatives such as cellulose esters generally have a strong polarity, so it is necessary to select a plasticizer having a strong polarity. However, compatibility between the two, plasticization efficiency, high transparency, non-volatility, non-migration, etc. Plasticizers that meet a wide range of performance are not among the known low molecular weight plasticizers,
Since the plasticizer is liable to volatilize during or after molding, there are also problems such as deterioration of the molding work environment and dimensional stability of the molded product. In addition, the plasticizer migrates to the adhesive layer or the printing surface of the marking film, leading to a decrease in the adhesive force of the former and a dust adhesion contamination of the latter. In the end, the use of low-molecular-weight plasticizers for cellulose derivatives, such as cellulose esters, is limited, and at present it is hindering the expansion of applications to films or sheets using such materials, especially marking films. .

In order to overcome the limit of use of the low molecular weight plasticizer, for example, Japanese Patent Publication No. 43-16305 discloses a cellulose acetate which is a fatty acid cellulose ester having an average molecular weight of 7 obtained from glycol and an aliphatic dibasic acid.
A technique of adding a polyester having a molecular weight of from 4,000 to 4,000 as a polymeric plasticizer is disclosed.
It has excellent compatibility with cellulose acetate having a degree of substitution of 2.2 or more. U.S. Pat. No. 3,781,381 discloses a technique in which a cyclic polymer such as ε-caprolactone is added to cellulose acetate (degree of substitution 2.5) as a cellulose ester. Further, U.S. Pat. No. 4,731,122 discloses that cellulose acetate butyrate and cellulose acetate include:
A thermoplastic resin composition comprising tributyl citrate, triethyl citrate, and polyethylene glycol is disclosed. However, the high-molecular plasticizer is still insufficiently compatible with the cellulose ester, and particularly when applied to a cellulose ester having a low degree of substitution, prevents the plasticizer from oozing out of the molded article and preventing volatilization from the molded article. It is difficult to do so, and this has an adverse effect on the appearance of the molded article, such as opacity due to phase separation, and on the physical properties, such as a decrease in the plastic effect.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent marking film which eliminates the problems relating to the volatility and migration of a conventional plasticizer to which a plasticizer has been added. The task is to do so.

[0009]

Means for Solving the Problems The present inventor has conducted intensive studies in view of the above situation, and as a result, has found that a fatty acid cellulose ester derivative obtained by subjecting a cyclic ester to ring-opening graft polymerization to a fatty acid cellulose ester having a hydroxyl group is not. The inventors have found that they are excellent in volatility and non-migratory property and are suitable for use as a marking film, and have led to the present invention.

Hereinafter, the gist of the present invention will be described. A first invention is a base film for a marking film, comprising a resin containing a fatty acid cellulose ester derivative as a main component obtained by ring-opening graft polymerization of a cyclic ester to a fatty acid cellulose ester having a hydroxyl group.
The second invention is the base film for a marking film according to the first invention, wherein the fatty acid cellulose ester having a hydroxyl group is at least one selected from the group consisting of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. About. The third invention relates to the base film for a marking film according to the first or second invention, wherein the fatty acid cellulose ester having a hydroxyl group is cellulose acetate having an acetyl group substitution degree of 1 to 3. A fourth invention relates to the base film for a marking film according to any one of the first to third inventions, wherein the cyclic ester is ε-caprolactone. The fifth invention is directed to a fatty acid cellulose ester having a hydroxyl group, wherein ε-
The present invention relates to the base film for a marking film according to any one of the first to fourth inventions, wherein 2 to 50 mol of caprolactone is graft-polymerized. The sixth invention is that the fatty acid cellulose ester derivative has a weight average molecular weight of 20.
The present invention relates to the base film for a marking film according to any one of the first to fifth aspects of the present invention, which has a number of 10,000 to 2,000,000.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail. According to the present invention, the fatty acid cellulose ester having a hydroxyl group refers to those in which the hydroxyl group of cellulose is esterified with a fatty acid while leaving a part thereof, and as the fatty acid cellulose ester, for example, cellulose acetate, cellulose acetate propionate, Cellulose esters such as cellulose acetate butyrate, cellulose acetate phthalate, and cellulose nitrate can be exemplified. Of these, cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate are preferred, and cellulose acetate is particularly useful. An average of 1 to 2.9 ester bonds consisting of a fatty acid and a hydroxyl group of a glucose unit of cellulose,
That is, the degree of substitution is preferably from 1 to 2.9, and thus the number of remaining hydroxyl groups is preferably from 0.1 to 2 on average, and particularly preferably from 0.2 to 0.2 on average.
Nine are preferred.

The cyclic ester according to the present invention is not particularly limited as long as it can undergo ring-opening polymerization.
For example, β-propiolactone, δ-valerolactone,
ε-caprolactone, α, α-dimethyl-β-propiolactone, β-ethyl-δ-valerolactone, α-methyllactone, β-methyl-ε-caprolactone, γ-methyl-ε-caprolactone, 3,3 5-trimethyl-
lactones such as ε-caprolactone, 3,5,5-trimethyl-ε-caprolactone, and enantholactone;
And cyclic esters such as glycolide and lactide. The cyclic ester according to the present invention is not limited to a single type, but may be a combination of a plurality of the above various types. As the cyclic ester, ε-caprolactone, which is particularly easily available industrially, is relatively inexpensive, and has excellent compatibility with the fatty acid cellulose ester according to the present invention, such as cellulose acetate, is particularly suitable.

There is no particular limitation on the charging ratio of the fatty acid cellulose ester having a hydroxyl group and the cyclic ester for obtaining the fatty acid cellulose ester derivative according to the present invention.
It can be appropriately selected depending on the form of use as a base film for a marking film. For example, when a marking film is attached to a curved surface, the flexibility of the base film for the marking film is required, so that it is preferable to increase the charging ratio of the cyclic ester. In order to graft polymerize a cyclic ester to a fatty acid cellulose ester having a hydroxyl group, generally, the former is 1 to 85% by weight.
The ratio of the latter is preferably 15 to 99 wt%. When the charged ratio of the fatty acid cellulose ester having a hydroxyl group exceeds 85 wt%, the viscosity of the reaction system becomes extremely high,
It becomes difficult to handle. Conversely, if it is less than 1 wt%, the productivity will decrease. When the viscosity is too high to handle easily, an organic solvent without active hydrogen having good compatibility with fatty acid cellulose acetate and cyclic ester or a polyhydric alcohol having reactivity is added as a third component. Can be reduced to facilitate the reaction.

The catalyst used for the graft polymerization of a cyclic ester, particularly a lactone, to a fatty acid cellulose ester having a hydroxyl group according to the present invention includes a catalyst usually used for a ring opening reaction of a cyclic ester, for example, sodium, potassium, etc. Derivatives such as alkali metals or alkoxides thereof, alkylaluminums and derivatives thereof represented by triethylaluminum, alkoxytitanium compounds represented by tetrabutyl titanate, organic metals or metal complexes such as tin octylate, dibutyltin laurylate, and organic tin And the like. The preferred catalyst used for producing the fatty acid cellulose ester derivative according to the present invention is tin octylate.

In order to obtain the above-mentioned fatty acid cellulose ester derivative which is a graft polymer according to the present invention, a conventional stirrer, a reactor equipped with a reflux condenser (with a drying tube), and a twin-screw extruder are used. It is preferably used. The polymerization temperature for obtaining the above-mentioned derivative according to the present invention is usually preferably the temperature applied to ring-opening polymerization of a cyclic ester, and is preferably from 100 to 210 ° C. Further, the polymerization reaction time, the type of each of the fatty acid cellulose ester having a hydroxyl group and the cyclic ester, the charging ratio, the type and amount of the catalyst, the reaction temperature, further varies depending on the reaction apparatus, is not particularly limited, Preferably, it is 1 to 8 hours.

Further, when obtaining the graft polymer according to the present invention, it is desirable that each raw material, nitrogen, a reactor and the like used in the polymerization reaction are sufficiently dried. Further, the water content of the reaction system is 0.1 wt% or less, preferably 0.1 wt%.
01 wt% or less, more preferably 0.001 wt% or less.

The molecular weight of the reaction product thus obtained also depends on the molecular weight of the starting fatty acid cellulose ester having a hydroxyl group and the type of the cyclic ester to be grafted. Those having a weight average molecular weight in the range of 200,000 to 2,000,000 are preferable, and 300,000 to 1,000,000 are more preferable. When the weight average molecular weight is less than 200,000, the weight average molecular weight of the original cellulose acetate is 1570,000, and the amount of the added cyclic ester is small, and the flexibility of the base film for a marking film obtained from the graft polymer is reduced. Tends to be insufficient. On the other hand, if it exceeds 2,000,000, the viscosity of the graft polymer is too high, and molding problems are likely to occur.

The average graft polymer obtained by the polymerization reaction at the charged ratio of the fatty acid cellulose ester having a hydroxyl group and the cyclic ester is preferably from 2 to 50 mol of ε-caprolactone per residual hydroxyl group in the glucose unit. The compound having a structure obtained by addition polymerization of 5 to 20 mol is more preferable, and the compound having a structure formed by addition polymerization of 5 to 20 mol is most preferable.

The internal plasticizing effect of the fatty acid cellulose ester by adding the cyclic ester can lower the melting temperature of the product and increase the thermal decomposition temperature.
Thus, molding can be performed by a molding means used for processing a normal thermoplastic resin, for example, injection molding, extrusion molding, press molding, or the like, without adding a large amount of a plasticizer. In addition, the molding material internally plasticized with the cyclic ester according to the present invention has no migration property, so that even if the molding material is left under high temperature and high humidity in contact with other moldings, it will attack the other moldings. There is no fear.

In the fatty acid cellulose ester derivative according to the present invention, various stabilizers such as antioxidants and ultraviolet absorbers, dyes and pigments, fillers and lubricants can be used in the same manner as in the case of ordinary resins or resin compositions. , Additives such as antistatic agents, flame retardants,
Depending on the purpose, it may be used alone or in combination of several kinds.

As an optimal molding method of the fatty acid cellulose ester derivative for use as a base film for a marking film according to the present invention, a cast molding method and a calendar molding method are preferred, and a cast molding method is particularly preferred. When forming a film by the cast molding method, it is preferable that a fatty acid cellulose ester derivative composition is once formed by adding an appropriate plasticizer or a solvent to the above fatty acid cellulose ester derivative as necessary and mixing. In this case, the other various additives can be added and mixed as desired. The fatty acid cellulose ester derivative composition thus obtained can flow freely only by gravity to give a desired shape without the need to apply a special external stress, so that the solution is simply heated and dried. It can be formed into a film to give a desired cast film. The heating and drying conditions in this case include, for example, about 30 to about 200 ° C., about 2 to about 1
Conditions such as 20 minutes can be exemplified.

[0022]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these contents. (Examples 1 to 4) In a reactor equipped with a stirrer, a thermometer, and a reflux condenser (with a drying tube at the top), absolute parts of absolutely dry cellulose acetate shown in Table 1 below (Daicel Chemical Industries, Ltd.)
Acetylation degree 55%, substitution degree 2.45, described in the table as cotton wool) and purified ε-caprolactone, the water concentration in the reaction system was adjusted to 0.1 wt% or less, and the mixture was heated to 180 ° C. ,
The cellulose acetate was uniformly dissolved by stirring. After confirming the uniform dissolution state, 0.24 parts of tin (II) octoate was added dropwise as a catalyst, and after allowing the reaction to proceed for 4 hours, the graft was taken out of the reactor. The resulting resin was dried with hot air at 90 ° C. for 8 hours, then melted at 230 ° C. using an injection molding machine, and injection-molded to prepare a test piece for evaluating physical properties. The properties were measured and the presence or absence of migration of components other than the cotton wool was observed and evaluated. Table 2 shows the evaluation results.
(1) to (3). (1) Presence or absence of migration of components other than cotton wool: Observation of the presence or absence of the components adhering to the surface of the molded article. (2) Bleed-out test: The degree of weight loss of a 5 cm × 5 cm square injection molded product was measured under the following measurement conditions. (a) Test using hot air dryer: 80 ° C. × 1 day, 4 days (3) Tensile test: According to JIS K7113.

(Comparative Examples 1-2) Absolutely dried cellulose acetate (manufactured by Daicel Chemical Industries, Ltd., 55% acetylation, substitution degree 2.45) used in Examples 1-4, 100 parts by weight), 40 parts by weight of a plasticizer diethyl phthalate (DEP) (Comparative Example 1) and 40 parts by weight of Cell Green ^™ 3058 (a trifunctional lactone polyol having a molecular weight of 500, manufactured by Daicel Chemical Industries, Ltd.) Various plasticizer-containing compositions to which each of Comparative Example 2) was added were prepared, dried with hot air at 50 ° C. for 12 hours, melted at 230 ° C. using an injection molding machine, and tested in the same manner as in Examples. A piece was prepared, measured for tensile properties and bleed-out properties, and observed for the migration of components other than cotton wool, such as a plasticizer, and evaluated. The composition is shown in Table 1, and the results of each evaluation are shown in Tables 2 (1) to (3).

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

The base film for a marking film according to the present invention using a fatty acid cellulose ester derivative obtained by subjecting a fatty acid cellulose ester having a hydroxyl group to ring-opening graft polymerization with a fatty acid cellulose ester has a conventionally known addition type low molecular weight or Compared to the case of high molecular weight plasticizer,
Since the composition does not contain a migrating additive, it is most suitable for use of the derivative.

Claims (6)

[Claims] 1. A base film for a marking film, comprising a resin containing a fatty acid cellulose ester derivative as a main component obtained by ring-opening graft polymerization of a cyclic ester to a fatty acid cellulose ester having a hydroxyl group. 2. The base film for a marking film according to claim 1, wherein the fatty acid cellulose ester having a hydroxyl group is at least one selected from the group consisting of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. 3. The base film for a marking film according to claim 1, wherein the fatty acid cellulose ester having a hydroxyl group is cellulose acetate having an acetyl group substitution degree of 1 to 3. 4. The base film for a marking film according to claim 1, wherein the cyclic ester is ε-caprolactone. 5. The amount of ε-caprolactone is 2 to 2 per glucose unit of the fatty acid cellulose ester having a hydroxyl group.
The base film for a marking film according to any one of claims 1 to 4, which is graft-polymerized by 50 mol. 6. The base film for a marking film according to claim 1, wherein the fatty acid cellulose ester derivative has a weight average molecular weight of 200,000 to 2,000,000.