JP3252657B2 - Biodegradable paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating composition such as a printing ink or a coating agent. More particularly, it relates to a biodegradable coating composition.

[0002]

2. Description of the Related Art Many conventional plastics have a property that they remain in the environment as they are without undergoing biodegradation even if they are disposed of in the soil as garbage, which has a serious adverse effect on the global environment. Problem.

For this reason, biodegradable plastics have been developed which are naturally degraded by microorganisms in the soil even if they are disposed of in the environment, and some of them are commercially available (trade name: Biopol, manufactured by Zeneca, UK; (Bionore, manufactured by Showa Kogyo; polylactic acid, manufactured by Shimadzu Corporation). These are all aliphatic polyesters having a number average molecular weight of 35,000 or more, and are used in melt thermoforming applications, for example, injection moldings such as various plastic bottles, and films such as garbage bags.

[0004] Incidentally, biodegradable plastic products molded from these biodegradable plastics usually include:
Printing of characters and patterns and surface coating are performed. In this case, various binder resins are contained in the printing ink and various coating agents to be used, and non-biodegradable binder resins have been used as such binder resins. For this reason, even if it is a biodegradable plastic product, the printed portion and the surface coat layer become non-biodegradable, and when discarded in the soil, they remain in the soil without being decomposed and pollute the environment. There is a problem.

[0005] For this reason, such degradable plastic products as well as binder resins for coating inks such as printing inks or surface coating agents for various printing media such as cards and posters, as well as the above-mentioned degradable plastics. Attempts have been made to impart biodegradability to a coating film by using plastic.

[0006]

By the way, the above-mentioned conventional biodegradable plastics are easily dissolved in a chlorine-based solvent which has a strong adverse effect on the human body and the environment. However, such as ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, etc. It has the property that it is hardly soluble in industrial general-purpose solvents. For this reason, when preparing a coating composition using a biodegradable plastic, there is a problem that an industrial general-purpose solvent having less pollution problem cannot be used.

In addition, since conventional biodegradable plastics do not exhibit thermosetting properties, there is a problem that the strength of a coating film formed therefrom is insufficient.

The present invention is intended to solve the above-mentioned problems of the prior art, and provides a coating composition using a biodegradable polymer as a resin binder with good solubility in general-purpose industrial solvents. Another object is to form a tough coating film from the coating composition.

[0009]

Means for Solving the Problems The present inventors have found that a biodegradable polymer having a molecular weight in a specific range includes ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene,
Completed the present invention by finding that it is soluble in various industrial solvents such as xylene, tetrahydrofuran, and cyclohexanone, and that a tough coating film can be formed by reacting the polymer with a crosslinking agent in the presence of a crosslinking catalyst. It led to.

That is, the present invention provides a number average molecular weight of 15,000.
In the following , the hydroxyl value of the molecular terminal is 5 to 100, or the acid value
A biodegradable coating composition comprising an aliphatic polyester having a molecular weight of 5 to 100, a soil biodegradable polymer, a crosslinking catalyst, and a non-halogen solvent.

Hereinafter, the present invention will be described in detail.

The biodegradable polymer which is a resin binder of the biodegradable coating composition of the present invention has a number average molecular weight of 15 in order to ensure solubility in general-purpose industrial solvents.
000 or less, preferably 2000 to 10000. Therefore, the concept of the biodegradable polymer used in the present invention includes its oligomer.

As such a biodegradable polymer, it is preferable to use an aliphatic polyester from the viewpoint of coating film strength. In this case, if the number of hydroxyl groups or carboxyl groups at the molecular terminals is too small, the amount of the cross-linking agent that reacts is small, so that the coating film cannot be made sufficiently tough,
On the other hand, if it is too much, it excessively reacts with the crosslinking agent and the coating film becomes too hard. Therefore, as the aliphatic polyester, those having a hydroxyl value or an acid value at the molecular terminal of preferably 5 to 100, more preferably 10 to 90 are used.

Specific examples of such a biodegradable polymer having a hydroxyl group or a carboxyl group at its terminal include polypropylene succinate, polypropylene adipate, polypropylene pimerate, polypropylene suberate, polypropylene azelate, polypropylene malonate, and polypropylene diethyl. Glutarate, polyethylene succinate, polyethylene adipate, polyethylene pimerate, polyethylene suberate, polyethylene azelate, polyethylene malonate, polyethylene diethyl glutarate, polybutylene succinate,
Polybutylene adipate, polybutylene pimerate, polybutylene verate, polybutylene azelate, polybutylene malonate, polybutylene diethyl glutarate, polyhexamethylene succinate, polyhexamethylene adipate, polyhexamethylene pipe Melate, polyhexamethylene suberate, polyhexamethylene azelate, polyhexamethylene malonate, polyhexamethylene diethyl glutarate, polydiethylene succinate, polydiethylene adipate, polydiethylene pimerate, polydiethylene suberate, polydiethylene Azelate, polydiethylene malonate, polydiethylene diethyl glutarate, polytriethylene succinate,
Aliphatic polyesters such as polytriethylene adipate, polytriethylene pimerate, polytriethylene suberate, polytriethylene azelate, polytriethylene malonate, polytriethylene diethyl glutarate, and polycaprolactone are preferred. Also, although the biodegradation rate is somewhat inferior to aliphatic polyesters, polyesters having alicyclic compounds in the molecular structure, for example, polybutylenecyclohexadimetallate, polyhexamethylenecyclodimetallate, polycyclohexanecyclohexanate, etc. Alternatively, polyesters containing aromatics in the structure can also be used. These polyesters may be used alone or as a blend of two or more. Further, it may be used as a copolymer.

The crosslinking agent used in the present invention includes:
Isocyanate compounds and epoxy compounds which initiate a crosslinking reaction upon heating can be preferably used. Therefore, the biodegradable coating composition of the present invention using these crosslinking agents is a thermosetting coating composition.

The isocyanate compound can be preferably used for crosslinking an aliphatic polyester having a hydroxyl value of 5 to 100, preferably 10 to 90. Epoxy compounds can be preferably used for crosslinking aliphatic polyesters having an acid value of 5 to 100, preferably 10 to 90.

Preferred examples of such isocyanate compounds include hexamethylene diisocyanate and its trimer type, buret type, TMP adduct type, isophorone diisocyanate, tolylene diisocyanate, tetramethyl xylene diisocyanate, and the like. In this case, as a crosslinking catalyst, triethylamine, triethylenediamine, tin octoate, dibutyltin diacetate, dibutyltin 2
-Ethylhexoate, zinc 2-ethylenehexoate, sodium o-phenolphenate, potassium oleate, tetra (2-ethylhexyl) titanate,
Ferric 2-ethylhexoate, 2-ethylhexoate cobalt, zinc naphthenate, antimony trioxide, and the like can be used.

Epoxy compounds include trifunctional epoxy compounds such as trimethylolpropane triglycidyl ether and glycerin diglycidyl ether, and propylene glycol glycidyl ether, 1,6-hexanediol diglycidyl ether and ethylene glycol glycidyl ether. And bifunctional epoxy compounds. Among them, it is preferable to use a trifunctional epoxy compound for forming a tough coating film. in this case,
Crosslinking catalysts that promote the crosslinking reaction include acetylacetonate chromium, zinc acetylacetonate, nickel acetylacetonate, cobalt acetylacetonate, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, benzyldimethylamine, tetraethylammonium tetrafluoroborate , Triethanolamine borate, triethanolamine titanate, tin octylate, quaternary phosphonium salts, quaternary organic arsonium salts, imidazolium salts,
Amine imide and the like can be used.

As the non-halogen solvent used in the biodegradable coating composition of the present invention, it is preferable to use general industrial solvents such as ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, tetrahydrofuran, and the like. And cyclohexanone. These may be used as a mixture of two or more.

The biodegradable coating composition of the present invention may contain various additives depending on the intended use, such as inorganic pigments, dyes,
A dispersant or the like may be added.

The biodegradable coating composition of the present invention can be produced by a conventional method. For example, it can be produced by dissolving or dispersing a biodegradable polymer, a cross-linking agent, a cross-linking catalyst, and if necessary, other additives in a non-halogen solvent.

When a film is formed using the biodegradable coating composition thus obtained, known coating (or printing) methods such as a wire bar coating method, a roll bar coating method, a screen printing method, and a gravure printing method are used. The composition is applied to a medium to be coated (printed) by using the method, and after drying or simultaneously with drying, the composition is subjected to a crosslinking reaction. Thereby, a biodegradable and tough coating film is obtained.

[0023]

The biodegradable coating composition of the present invention has a molecular weight of 150
It contains a biodegradable polymer of 00 or less as a resin binder. Therefore, the solubility in industrial general-purpose solvents is improved. Further, since this composition contains a crosslinking agent and a crosslinking catalyst, it can be rapidly crosslinked by heating to give a tough coating film.

Further, since the coating film formed from the biodegradable coating composition contains a biodegradable polymer as a main component, when it is discarded, it is decomposed and lost by microorganisms in the environment.

[0025]

The present invention will be described below in more detail with reference to examples.

Example 1 As a biodegradable polymer, 100 parts by weight of polytetramethylene adipate having a number average molecular weight of 2,300 and a hydroxyl value of about 53 (KOH mg / g) was sufficiently dissolved in a toluene solvent. Further, 18 parts by weight of hexamethylene diisocyanate trimer type as a crosslinking agent and 0.5 parts by weight of dibutyltin diacetate as a crosslinking catalyst are added to the solution, and the mixture is sufficiently stirred to obtain a biodegradable resin coating composition. Was.

The obtained coating composition was applied on a glass substrate to a thickness of about 10 μm in a dry thickness, and then dried at 70 ° C. for about 2 hours with an electric dryer and at the same time sufficiently thermally crosslinked.

The biodegradability of the coating film formed on the glass substrate was evaluated by a soil burial method. That is, when this glass substrate was buried at a depth of about 10 cm in the soil of Sugito-machi, Kita-Katsushika-gun, Saitama, the coating film on the glass substrate completely disappeared after about 6 months.

Example 2 As a biodegradable polymer, 100 parts by weight of polyhexamethylene succinate having a number average molecular weight of 4,200 and a hydroxyl value of about 82 (KOH mg / g) was sufficiently dissolved in an ethyl acetate solvent. To the solution, 29 parts by weight of hexamethylene diisocyanate trimer type as a crosslinking agent and 1 part by weight of dibutyltin diacetate as a crosslinking catalyst were further added,
Subsequently, 250 parts by weight of magnetic iron oxide was dispersed to obtain a biodegradable resin magnetic coating composition.

This magnetic coating composition is applied on a paper web having a thickness of about 180 μm to a dry thickness of about 10 μm, and then dried at 70 ° C. for about 2 hours in an electric dryer and simultaneously thermally crosslinked. Was. Then, a paper magnetic card was produced by punching the paper stock into a card type.

The biodegradability of the magnetic coating film formed on the surface of the paper magnetic card was evaluated by the soil burial method. That is,
When this paper magnetic card was buried at a depth of about 10 cm in the soil of Sugito-cho, Kita-Katsushika-gun, Saitama Prefecture, it completely disappeared after about 8 months including the paper as the card base material.

Example 3 As a biodegradable polymer, 100 parts by weight of polyethylene adipate having a number average molecular weight of 10,000 and a hydroxyl value of about 73 (KOH mg / g) was dissolved in methyl ethyl ketone.
The solution was further added with 12 parts by weight of hexamethylene diisocyanate as a crosslinking agent and dibutyltin 2 as a crosslinking catalyst.
-0.8 parts by weight of ethylhexoate was added thereto, and the mixture was sufficiently stirred to obtain a biodegradable resin coating composition.

The obtained coating composition was applied on a glass substrate in a dry thickness of about 10 μm, and then dried at 70 ° C. for about 2 hours with an electric drier, and sufficiently thermally crosslinked.

[0034] The biodegradability of the coating film formed on the glass substrate was evaluated by the soil burying method. That is, when this glass substrate was buried at a depth of about 10 cm in the soil of Sugito-machi, Kita-Katsushika-gun, Saitama, the coating film on the glass substrate completely disappeared after about 6 months.

Example 4 As a biodegradable polymer, polycaprolactone 1 having a number average molecular weight of 2000 and a hydroxyl value of about 50 (KOH mg / g) was used.
00 parts by weight were dissolved in methyl ethyl ketone. To the solution, 30 parts by weight of a TMP adduct of hexamethylene diisocyanate as a cross-linking agent and 0.8 part by weight of a cross-linking catalyst dibutyltin 2-ethylhexoate are added, and the mixture is sufficiently stirred to obtain a biodegradable resin. A coating composition was obtained.

The obtained coating composition was applied on a glass substrate in a dry thickness of about 10 μm, and then dried at 70 ° C. for about 2 hours with an electric drier, and sufficiently thermally crosslinked.

The biodegradability of the coating film formed on the glass substrate was evaluated by the method of burying in soil. That is, when this glass substrate was buried at a depth of about 10 cm in the soil of Sugito-cho, Kita-Katsushika-gun, Saitama, the coating film on the glass substrate completely disappeared after about one year.

Example 5 As a biodegradable polymer, 100 parts by weight of polytetramethylene adipate having a number average molecular weight of 5,500 and an acid value of about 54 (KOH mg / g) was dissolved in methyl ethyl ketone. To this solution, 14 parts by weight of trimethylolpropane diglycidyl ether as a crosslinking agent and 1 part by weight of benzyltrimethylammonium chloride as a crosslinking catalyst were further added, and sufficiently stirred to obtain a biodegradable resin coating composition. .

The obtained coating composition was applied on a glass substrate in a dry thickness of about 10 μm, and then dried at 100 ° C. for about 2 hours with an electric drier, and sufficiently thermally crosslinked.

The biodegradability of the coating film formed on the glass substrate was evaluated by a soil burying method. That is, when this glass substrate was buried at a depth of about 10 cm in the soil of Sugito-cho, Kita-Katsushika-gun, Saitama, the coating film on the glass substrate completely disappeared after about 8 months.

Example 6 As a biodegradable polymer, polyhexamethylene succinate having a number average molecular weight of 4,500 and an acid value of about 81 (KOH mg / g) was dissolved in toluene. To this solution, 21 parts by weight of trimethylolpropane diglycidyl ether as a cross-linking agent and 1 part by weight of benzyltrimethylammonium chloride as a cross-linking catalyst were further added, and sufficiently stirred to obtain a biodegradable resin coating composition. .

The obtained coating composition was applied on a glass substrate at a dry thickness of about 10 μm, and then dried at 100 ° C. for about 2 hours with an electric drier, and sufficiently thermally crosslinked.

The biodegradability of the coating film formed on the glass substrate was evaluated by a soil burying method. That is, when this glass substrate was buried at a depth of about 10 cm in the soil of Sugito-cho, Kita-Katsushika-gun, Saitama, the coating film on the glass substrate completely disappeared after about one year.

[0044]

The biodegradable coating composition of the present invention can be prepared using a general-purpose industrial solvent. The coating film obtained from this coating composition is tough and biodegradable.

Claims (4)

(57) [Claims] 1. A compound having a number average molecular weight of 15,000 or less and a molecular terminal
From an aliphatic polyester having a hydroxyl value of 5 to 100
A biodegradable coating composition comprising a biodegradable polymer in soil, a crosslinking catalyst, and a non-halogen solvent. 2. A compound having a number average molecular weight of 15,000 or less and a molecular terminal
Consisting of an aliphatic polyester having an acid value of 5 to 100
Soil biodegradable polymer, cross-linking catalyst, non-halogen solvent
And a biodegradable coating composition comprising: 3. The method according to claim 1, wherein the crosslinking agent is an isocyanate compound.
The biodegradable coating composition according to claim 1. 4. The cross- linking agent is an epoxy compound.
The biodegradable coating composition as described in the above.