JP2002069341A - Ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition having an excellent performance and biodegradation property. SOLUTION: This ink composition contains an aliphatic polyester containing a structural unit expressed by formula (1) [R1 is an alkylene or polyalkylene group; R2 is an alkylene group; and (n) is >=1 integer] and containing a tertiary amino group in its main chain, an ink pigment and a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an ink composition, and more particularly to an ink composition improved to have biodegradability.

[0002]

2. Description of the Related Art In recent years, with the increasing awareness of environmental issues, products using natural materials or biodegradable synthetic materials have been actively developed.

[0003] When biodegradable films such as polylactic acid films have been used as packaging materials due to such trends in the world, urethane-based, acrylic-based, aromatic-based polyesters and the like which have been conventionally used are used as ink binders. Instead of the non-biodegradable ink used, a biodegradable ink is required.

In view of the above circumstances, the present applicant has already proposed a biodegradable ink using a lactic acid-based polyester as an ink binder (Japanese Patent Application Laid-Open No. 8-92518).

[0005]

However, ordinary organic solvent-soluble polylactic acid has problems in ink pigment dispersibility, ink stability, etc., and the emergence of a biodegradable ink excellent in these characteristics. Was desired.

[0006] Therefore, an object of the present invention is to provide an ink composition which is superior to conventional polylactic acid-based inks in ink pigment dispersibility and ink stability.

Another object of the present invention is to provide an ink composition having biodegradability.

[0008]

The ink composition according to the present invention comprises: an aliphatic polyester having a tertiary amino group in the main chain and containing a structural unit represented by the following formula (1): And a solvent.

[0009]

Embedded image

The aliphatic polyester of the formula (1) is obtained by copolymerizing a tertiary amine and a hydroxy acid.

The aliphatic polyester includes the tertiary tertiary compound.
Amino group is 5-100 equivalent / 10 ⁶g
Preferably it is rare. 5 equivalent / 10⁶g or less
Good pigment dispersibility and ink stability
No. In addition, 100 equivalent / 10⁶above g, good raw
Biodegradable ink with degradability and physical properties of coating film cannot be obtained.
No.

[0012] When the aliphatic polyester is a lactic acid-based polyester, it must contain at least 80 mol% of lactic acid residues, and preferably at least 90 mol%. If it is less than 80 mol%, good biodegradability and physical properties of the coating film cannot be obtained.

As lactic acid, any of L-lactic acid, D-lactic acid and DL-lactic acid can be used.

Further, the molar ratio of L-lactic acid to D-lactic acid (L / lactic acid)
D) needs to be 1 to 9, preferably 1 to 9.
5.6. If the L / D exceeds 9, the solubility of the polyester in the solvent used becomes poor, and the polyester cannot be used as an ink binder. If L / D is less than 1 (D-lactic acid excess), the raw material cost increases.

If the tertiary amino group is contained in the polylactic acid in an amount of 5 equivalents / 10 ⁶ g or more, the content of a hydroxy acid (copolymer component) other than lactic acid described later may be 0%.

The tertiary amine used in the present invention is
A tertiary amine represented by the following general structural formula (2) and having at least one hydroxyl group in the molecule. Of these, tertiary amines having at least two hydroxyl groups in the molecule are preferred. As the aliphatic tertiary amine preferably used in the present invention, triethanolamine, monoalkyldiethanolamine, dialkylmonoethanolamine and the like can be mentioned.

[0017]

Embedded image

The hydroxy acid copolymerized in the present invention is a compound having an alcoholic hydroxyl group and a carboxyl group in one molecule. Examples of the hydroxy acid include lactic acid described above, glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 16-hydroxyhexadecanoic acid, 2-hydroxy-2-methylbutyric acid, and 10-hydroxystearic acid. , Malic acid, citric acid, gluconic acid and the like are used.
In addition, intramolecular esters of hydroxy acids such as caprolactone, and cyclic esters formed by losing water molecules from α-hydroxy acids such as lactide are also used.

Next, a method for producing the above aliphatic polyester will be described. The method for producing the aliphatic polyester is not particularly limited, and a conventionally known method can be used. For example, lactide, which is a dimer of hydroxy acid, and the above tertiary amine are melt-mixed, and heated ring-opening polymerization is performed using a known ring-opening polymerization catalyst (for example, tin octylate, aluminum acetylacetonate, etc.). And a method of performing direct dehydration polycondensation by heating and reduced pressure.

Next, the characteristics of the obtained aliphatic polyester will be described. The reduced viscosity of the aliphatic polyester is preferably in the range of 0.3 to 1.5 dl / g. If the reduced viscosity is lower than 0.3 dl / g, repelling or the like at the time of printing may be caused, and if the reduced viscosity is too high, the ink viscosity increases and good printability cannot be obtained.

Incidentally, the reduced viscosity is determined by measuring the sample concentration at a concentration of 0.
It is a value measured using an Ubbelohde viscosity tube at 125 g / 25 ml, a measurement solvent of chloroform, and a measurement temperature of 25 ° C.

The glass transition temperature Tg of the aliphatic polyester according to the present invention is preferably 35 to 60 ° C. More preferably, it is 40 to 55 ° C. Within the range of 35 to 60 ° C, good adhesion strength to the biodegradable film and blocking resistance can be obtained.

The aliphatic polyester thus obtained preferably has biodegradability. Here, the term "biodegradable" refers to the property of being converted into a low-molecular-weight compound in the course of decomposition by involving the metabolism of an organism.

The glass transition point Tg can be adjusted, for example, by changing the proportion of the polyester copolymer component. The Tg is a value measured by a DSC (differential scanning calorimeter) method.

Next, the method for producing the ink composition will be described. The method is not particularly limited as long as it is a conventionally known method. For example, an ink can be produced by dissolving an aliphatic polyester in a solvent, adding an ink pigment thereto, and dispersing the resulting mixture using a ball mill or a paint shaker.

The ink pigment used in the production of the ink is not particularly limited as long as it is commonly used. Examples thereof include titanium oxide, calcium carbonate, barium sulfate, yellow iron oxide, red iron oxide, carbon black, aluminum powder, and mica. , Titanium powder, phthalocyanine and the like.
These can be used alone or in combination of two or more.

As the solvent used in the production of the ink, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, and the like are preferable from the viewpoints of solubility of aliphatic polyester, workability, drying speed and the like.
Toluene, xylene, isopropyl alcohol and the like are used. These can be used alone or in combination of two or more.

The amounts of the above components in the ink composition according to the present invention are 1 to 1000 parts by weight of the ink pigment and 100 parts by weight of the solvent with respect to 100 parts by weight of the aliphatic polyester.
It is preferable to add ２０００2000 parts by weight. More preferably, it is 2 to 500 parts by weight of the ink pigment and 200 to 1500 parts by weight of the solvent with respect to 100 parts by weight of the aliphatic polyester.

The ink composition according to the present invention may further contain, if necessary, a crosslinking agent such as a polyfunctional isocyanate, a polyfunctional epoxy, or melamine, a pigment dispersant, or a viscosity modifier in addition to the above components. Can be.

The ink composition of the present invention can be used, for example, for printing labels and packaging films based on a biodegradable film such as a polylactic acid film, and is widely used as a biodegradable ink for paper. Can be used.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 A four-necked flask was charged with 100 parts of DL-lactide, 100 parts of L-lactide, 1.357 parts of methyl-diethanolamine, and 0.1 part of aluminum acetylacetonate as a ring-opening polymerization catalyst. At 190 ° C. for 1 hour to effect ring-opening polymerization to obtain a polyester (I) containing a tertiary amine in the main chain.

Next, 100 parts of the above-mentioned polyester (I) was dissolved in 200 parts of toluene, and 10 parts of carbon black were mixed and dispersed in a ball mill.
The mixture was diluted with 0 parts to obtain a black ink (I).

Example 2 A four-necked flask was charged with 100 parts of DL-lactide, 100 parts of L-lactide, 0.452 part of triethanolamine, and 0.1 part of aluminum acetylacetonate as a ring-opening polymerization catalyst. Polymerization was carried out in the same manner as in the above to obtain polyester (II).

Example 1 was also applied to polyester (II).
Ink ink (II) was obtained in the same manner as described above.

Comparative Example 1 100 parts of L-lactide, 100 parts of DL-lactide, and aluminum acetylacetonate 0.1 as a ring-opening polymerization catalyst.
One part was charged into a four-necked flask and polymerized in the same manner as in Example 1 to obtain a polyester (III).

With respect to the polyester (III), a black ink (III) was obtained in the same manner as in Example 1.

Comparative Example 2 A black ink (IV) was obtained in the same manner as in Example 1 using Byron RV103 (registered trademark: manufactured by Toyobo Co., Ltd.) which was an aromatic polyester resin.

Table 1 shows the composition and physical properties of the polyester used in the above Examples and Comparative Examples.

[0040]

[Table 1]

The reduced viscosity was determined to be 0.12 in sample concentration.
5 g / 25 ml, measurement solvent chloroform, measurement temperature 25
At 0 ° C., it was measured using an Uberose viscosity tube. Also, Tg
Was measured by the DSC method. Further, in Table 1, the lactic acid residue in the lactic acid-based polyester composition defines the charged amount. However, NMR at 500 MHz confirmed that the same amount was contained in the polyester.

Further, L-lactic acid and D in the polyester
-The molar ratio of lactic acid is determined from the charged amount, and is the same as the molar ratio of L-lactic acid and D-lactic acid in the polyester determined using a polarimeter (HORIBA SEPA-200). Was confirmed.

Experimental Example Using the inks obtained in the above Examples and Comparative Examples, printing was performed on a polylactic acid film with a gravure printing machine to obtain a printed film. Using this printed film, the ink performance (pigment dispersibility, ink stability, printability, adhesiveness) and biodegradability were evaluated as follows. Adhesiveness and biodegradability were evaluated on a 5-point scale, from 5 (very good) to
1 (bad). In practice, it is 4 or more.

1) Pigment dispersibility: The dispersibility of the pigment was evaluated using a gloss meter. 2) Ink stability: The change over time of the ink is visually inspected,
The degree of separation and sedimentation of the pigment was visually evaluated.

3) Printability: Gravure printing was performed on the polylactic acid film, and the presence or absence of cissing was visually evaluated.

4) Adhesion: The grid was cut, and the adhesion was evaluated by peeling off Cellotape (registered trademark). 5) Biodegradability: 10 cm x 10 cm of the above printed film
The poster (garbage disposal machine, manufactured by Mitsui Home Co., Ltd. [MA
M]), and after 7 days, the morphology (degree of decomposition) of the sample was visually evaluated. The larger the degree of decomposition, the better.

Table 2 shows the results.

[0048]

[Table 2]

[0049]

As described above, according to the present invention, since an aliphatic polyester containing a tertiary amino group in the main chain is used as a binder, excellent ink performance and biodegradability were exhibited.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takashi Miyamoto 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. Research Institute (72) Inventor Takeshi Ito 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. (72) Inventor Katsuya Shidano 2-1-1 Katata, Otsu City, Shiga Prefecture Inside Toyobo Co., Ltd. (72) Inventor Toshiko Shibasaki 2-1-1 Katata, Otsu City, Shiga Prefecture No. Within Toyobo Co., Ltd. Research Laboratory (72) Inventor Yasutori Hotta 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory (72) Inventor Jiro Watanabe 1-5-Taito, Taito-ku, Tokyo No. 1 Letterpress Printing Co., Ltd. (72) Inventor Shunichi Kato 2-3-13-1 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd. (72) Akita Yoshito Ichikawa 2-3-113 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd. (72) Inventor Fumio Watanabe 2-3-113 Kyobashi, Chuo-ku, Tokyo F-term in Toyo Ink Manufacturing Co., Ltd. 4J029 AA02 AB07 AC02 AD01 AD07 AE11 BH01 DA07 EA05 EH03 4J039 AE06 BA04 BA06 BA13 BA16 BA18 BA23 BA32 BA35 BA37 BA39 BC04 BC08 BC18 BC22 BC23 BC60 BE01 CA07 DA02 EA44 EA48 FA02

Claims (8)

[Claims] 1. The following formula (1) containing a tertiary amino group in the main chain:
An ink composition comprising: an aliphatic polyester containing a structural unit represented by the formula: an ink pigment; and a solvent. Embedded image 2. The ink composition according to claim 1, wherein the tertiary amino group is contained in the aliphatic polyester in a concentration range of 5 to 100 equivalent / 10 ⁶ g. 3. The aliphatic polyester has a lactic acid residue of 8
The ink composition according to claim 1, which contains 0 mol% or more. 4. The ink composition according to claim 3, wherein the aliphatic polyester contains an L-lactic acid residue and a D-lactic acid residue, and the L / D molar ratio is selected from 1 to 9. 5. The reduced viscosity (η) of the aliphatic polyester
_sp / c) is selected to be 0.3 to 1.5 dl / g.
The ink composition according to claim 1. 6. The ink composition according to claim 1, wherein the aliphatic polyester has a glass transition point (Tg) of 35 to 60 ° C. 7. The ink composition according to claim 1, wherein the tertiary amino group includes an aliphatic tertiary amino group. 8. The aliphatic polyester is biodegradable.
The ink composition according to claim 1.