JP2004210892A - Cellulose ester-based bonding or coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester-based bonding or coating composition having various characteristics such as biodegradability. <P>SOLUTION: The bonding or coating composition is prepared by dissolving a cellulose ester-made binding agent in a lactate, and, after application, is heated under decompression for the vaporization of the lactate for the solidification of the binding agent. For the recovery of the lactate vaporized during the binding agent solidifying process, the composition after application is heated under decompression for the lactate to vaporize in a decompression chamber, and the vapor is cooled and then the lactate is recovered. In case water vapor is also produced concurrently, the whole vapor is let through a dehydrating agent layer such as a molecular sieve 5A for the water vapor not to mix with the recovered lactate. A polylactic film is coated with the composition to obtain a laminated film strong against thermal impact. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cellulose ester-based adhesive or coating composition, a method and an apparatus for recovering a solvent in the composition, and a laminate having improved heat resistance of a polylactic acid film or sheet using the composition. It is about the body.
[0002]
[Prior art]
Cellulose acetate, nitrocellulose, etc. are compounds in which the hydroxyl groups contained in cellulose are esterified with an organic or inorganic acid. Cellulose acetate is used as artificial silk (acetate human silk), lacquer (paint), non-combustible film, electrical insulator, etc. Nitrocellulose for resin with a nitrogen content of 10.6-11.2% is used as a film or lacquer. Celluloid made by mixing camphor with nitrocellulose is widely used as toys, stationery and accessories. It is a known resin.
[0003]
[Problems to be solved by the invention]
By the way, with the advent of a variety of synthetic resins, cellulose ester resins have generally been forgotten. That is, cellulose ester is biodegradable and degrades when exposed to air for a long period of time. At present, petroleum-based polyester resins with little deterioration are mainly used as ester-based resins.
[0004]
However, due to problems such as environmental pollution caused by chemicals and industrial waste disposal, there is a new movement to review chemicals such as synthetic resins based on biodegradability as a value standard. As another problem, it is well known that formaldehyde used in building materials is a health problem.
[0005]
For example, polylactic acid has attracted attention because it has excellent mechanical strength and transparency in addition to biodegradability. However, heat resistance is as low as 70 ° C., and there is a drawback that the field of use is limited depending on the application, for example, it cannot be used when hot water disinfection is required. In this regard, cellulose acetate is considered to be a material to be newly investigated for its use, such as being biodegradable and having high heat resistance.
[0006]
However, acetone and nitrocellulose, which have been conventionally used, generally represent acetone, which evaporates even at room temperature, resulting in air pollution, and loss of the solvent greatly affects the manufacturing cost. Therefore, when a cellulose ester resin is used, it is necessary to consider the solvent to be used. The present invention has been completed by focusing on the above-described problems.
[0007]
That is, an object of the present invention is to provide a cellulose ester-based adhesive or coating composition using a lactic acid ester recognized as a food additive as a solvent.
[0008]
A second object of the present invention is to provide a laminate having improved heat resistance by coating a polylactic acid film or sheet having poor heat resistance with cellulose ester.
[0009]
Further, another object of the present invention is to provide an economical solvent recovery method and an apparatus therefor, since a lactic acid ester used as a solvent has a property that it does not easily evaporate at room temperature like a general solvent.
[0010]
[Means for Solving the Problems]
The cellulose ester-based dressing or coating composition of the present invention for achieving the above object comprises a bonding or coating composition obtained by dissolving a binder composed of cellulose ester in lactic acid ester, and after application, is heated under reduced pressure. Then, the lactate ester is evaporated to solidify the binder.
[0011]
The cellulose ester is not particularly limited, and cellulose acetate and nitrocellulose are representative from the past results. However, since nitrocellulose is flammable, a typical cellulose ester is cellulose acetate. Cellulose acetate and nitrocellulose are harmless to humans and animals and are biodegradable. They can be putrefied together with wood and paper-based materials into fertilizer in the fields, and can be completely recycled.
[0012]
As the lactic acid ester, for example, methyl lactate, ethyl lactate, propyl lactate, butyl lactate and the like can be used, and the most common one is ethyl lactate. These lactate esters can be handled as liquids that do not evaporate at room temperature.
[0013]
Various additives can be mixed into the cellulose ester adhesive in addition to the main material, if necessary.
[0014]
The cellulose ester-based coating agent can be used as a paint by mixing necessary pigments, extenders, and other various necessary additives. The term "coating agent" used in the present invention is intended to form a coating such as a so-called paint or a protective film, which is used for both protection and makeup of the surface of various objects.
[0015]
As described above, polylactic acid has a drawback of being inferior in heat resistance, but at the same time is insoluble in lactic acid ester, and cellulose acetate has a property of high adhesiveness to polylactic acid.
[0016]
As a method of applying the coating agent, a brush, a roller, a spatula, a doctor knife, an automatic coating machine and the like which are conventionally used can be used.
[0017]
Therefore, a laminate comprising the polylactic acid and the cellulose ester of the present invention is prepared by coating a coating composition obtained by dissolving a binder composed of the cellulose ester in a lactic acid ester onto a polylactic acid film or sheet, and heating the polylactic acid under reduced pressure to obtain a polylactic acid. The surface heat resistance of the molded product is improved.
[0018]
It is necessary to evaporate the lactic acid ester as a solvent from the cellulose ester-lactic acid ester composition under reduced pressure. Therefore, the method of recovering lactate from the cellulose ester-based dressing or coating composition of the present invention is to apply a bonding or coating composition in which a binder composed of cellulose ester is dissolved in lactate, and then reduce the pressure under heating. To evaporate the lactate ester and cool and collect the lactate ester vapor.
[0019]
Further, the apparatus comprises a reduced-pressure container and a lactate ester recovery device, and the reduced-pressure container has a container heating means in at least a part of the container and a binder made of cellulose ester dissolved in the lactate ester in the container. Heating means for heating the applied material of the bonding or coating composition, wherein the lactate ester recovery device comprises a cooling device for cooling and recovering the lactate ester vapor, and is interposed between the vacuum vessel and the vacuum pump; It was done.
[0020]
In addition, as a target to which the composition for cellulosic ester-based adhesive or coating is applied, there is a substance containing moisture such as wood. Therefore, the lactic acid ester recovery device of the present invention can be provided with a dehydrating device that allows the lactic acid ester vapor or the lactic acid condensate to pass through a dehydrating agent packed layer. There is no particular limitation on the dewatering material that can be used, but molecular sieves 5A or less can be used.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be specifically described with reference to embodiments.
(adhesive)
Ethyl lactate (10 parts by weight) was added to cellulose acetate (1 to 5 parts by weight), and the mixture was stirred well to form a uniform solution, thereby obtaining an adhesive composition A which was transparent and had a high viscosity at room temperature. This adhesive composition can be used as an adhesive for natural materials such as wood.
[0022]
(Coating agent)
One part by weight of cellulose acetate was mixed with 100 parts by weight of ethyl lactate to obtain a coating composition B comprising a uniform, transparent and highly fluid solution. When the coating agent is used as an adhesive, adding 1 part by weight of the calcium carbonate powder increases the bonding area and provides economy.
[0023]
The apparatus shown in FIG. 1 is an apparatus used in the first embodiment. After applying the adhesive and the coating agent, the solvent is evaporated to solidify the cellulose ester in the adhesive or coating agent composition, and This is a device for recovering the solvent separated by evaporation.
[0024]
The symbol C shown in FIG. 1 is prepared by preparing two 20 cm × 20 cm 2 mm thick plates, crossing the grain direction, and applying the adhesive composition A thinly on one surface of one plate with a spatula or the like. This is a sample for adhesion obtained by laminating the above plates.
[0025]
This sample C is placed on a heater 2 (a pedestal and the like is not shown) mounted in a decompression vessel 1 and pressed on a mold (not shown) having a hole made of aluminum thereon to heat the plate. Warpage was suppressed. Therefore, by using the cellulose ester adhesive composition of the present invention, plywood, plywood, tex with hardened fibers, laminated wood, and the like can be produced.
[0026]
The depressurizing device 1 is for bench test, and has a door 5 having a handle 4 attached to one opening of a cylindrical body, and a head plate having a pipe 6a connected to a vacuum pump (not shown) at the other opening. 7 is attached. 1, reference numeral 8 denotes a heating jacket, 10a denotes a heat medium inlet, 10b denotes a heat medium outlet, and 11 denotes a hinge of the door 5.
[0027]
The pipe 6a is connected to a solvent recovery device 12 for the evaporated ethyl lactate. The solvent recovery device 12 includes a solvent condensing unit 13 composed of a coiled cooling tube and a dehydrating unit 14 filled with a molecular sieve 5A or the like. The solvent condensed at the lower part (in this case, ethyl lactate) is collected and a vacuum valve 15 is provided. And a solvent recovery container 16 to which a pipe 6b connected to a vacuum pump is attached. In addition, the code | symbol 12a shown in FIG. 1 is an inflow port of cooling water, and 12b is an outflow port.
[0028]
When the temperature of the heating medium is maintained at 65 ° C. and the heater 2 is maintained at 120 to 130 ° C. and the pressure reducing device 1 is operated, the value of the vacuum gauge (not shown) will be as follows while the ethyl lactate continues to evaporate. There was no change and it changed to the vacuum side as the amount of evaporation decreased, indicating that the evaporation was completed. The vacuum pump was stopped, air was injected into the decompression device 1, and the sample C taken out had an extremely good adhesion.
[0029]
In the second embodiment, a 0.1 to 0.5 mm thick polylactic acid film (20 cm × 20 cm, not shown) is slightly tensioned on the heating device 2 of FIG. 1 so as not to bend. After being attached, the coating composition B was dropped on the surface and spread over the entire polylactic acid film with a doctor knife to obtain a coating sample (not shown).
[0030]
When the temperature of the heating medium of the pressure reducing device 1 was maintained at 60 ° C. and the temperature of the heating device 2 was maintained at 65 ° C., and the vacuum pump was operated, a polylactic acid / acetate cellulose laminated film (not shown) coated with cellulose acetate was obtained. . This film was subjected to a short-term heat shock at a temperature at which the polylactic acid alone softened and became difficult to maintain its shape, and it was observed that the shape stability was improved.
[0031]
FIG. 2 is a diagram illustrating the basic configuration of a continuous coating apparatus 19 for coating cellulose acetate on a polylactic acid film. In FIG. 2, a polylactic acid film 20 is wound on a bobbin 21, pulled out onto a heater 2 by a film feed roller 22, coated, and wound on a winding bobbin 23. The polylactic acid film 20 is coated with a cellulose ester-based coating composition B (not shown) by an automatic coating machine 24 attached to a predetermined position on the vessel 2, and the ethyl lactate is evaporated to form a laminated film. is there. The continuous coating device 19 can be mounted and used in the solvent recovery device shown in FIG.
[0032]
In the third embodiment, a lumber surface (not shown) is coated with the coating composition B, attached to a heater 2 in a decompression device 1 shown in FIG. 1, and ethyl lactate as a solvent is evaporated. A coated film having a good finish was obtained. By adding a paint component such as a pigment to the composition B, it is possible to obtain building materials and furniture without fear of a sick house.
[0033]
The third embodiment is applied to the manufacture of a pair of glass, and a 1 mm wide peripheral portion of a 20 mm × 20 cm square glass plate having a thickness of 2 mm is polished to form a cloudy glass. A string impregnated with the adhesive composition A, an epoxy adhesive and a non-return valve for plastic double glass were prepared (both not shown).
[0034]
An epoxy resin adhesive is thinly applied to the frosted glass portions of the two glass plates with a spatula or the like, the epoxy resin of one glass is applied, and the adhesive composition A is impregnated. An uncured pair made as a sandwich by placing the string as straight as possible and placing the check valve between both ends of the string without gaps, placing the other glass from above and pressing the glass so that there is no gap The glass was mounted on the heater 2 of FIG.
[0035]
When the heater 2 is energized, the temperature is maintained at 110 to 120 ° C., and when it is confirmed that the indicated value of the vacuum gauge has reached a sufficient vacuum and the ethyl lactate has sufficiently evaporated, the vacuum pump is stopped, taken out, and the check valve is exhausted. By closing the mouth with a sealant, the inside was decompressed to obtain a paired glass having soundproofing and heat insulating effects. As described above, the uncured epoxy resin and the cellulose acetate in the adhesive composition A in contact with the uncured epoxy resin have been completed after finding that an extremely good adhesive effect can be obtained after evaporating and removing ethyl lactate.
[0036]
FIG. 3 shows an aluminum die-cast split mold 25 used in the fourth embodiment, in which a through-hole 26 formed of a pinhole is provided on the entire surface of the split mold 25 so that the solvent evaporated inside can be expelled to the outside. Things. The split mold 25 was filled with wood litter, sawdust, etc., which had been sufficiently moistened by adding ethyl lactate to the adhesive composition A to reduce the viscosity (referred to as wood litter clay). Was evaporated for a sufficient time, and a wood-shaped shaping material was obtained according to the pattern. The split mold 25 in FIG. 3 is for testing, and the shape of the mold has no particular meaning.
[0037]
The mold shape of the split mold 25 was set to the shape of the target product, and the wood shaving clay was filled into the mold, and the aggregate formed of wood chips and coated with the adhesive composition A was embedded therein as necessary. By hardening, it is possible to manufacture a product similar to a finely carved woodwork product at low cost.
[0038]
【The invention's effect】
As described above, the cellulose ester-based adhesive or coating composition of the present invention has high safety to the human body, has biodegradability, and can be applied to adhesion and coating of various materials including natural materials such as wood. In addition, it can provide adhesives and coating materials that can be used jointly with other synthetic resin adhesives such as epoxy resin, and can recover various solvents, so that various molded products can be supplied economically. Can play. Further, heat shock resistance can be obtained by coating on a polylactic acid film.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a partially cutaway lactate ester recovery apparatus used for curing a cellulose adhesive and a coating agent according to the present invention.
FIG. 2 is an explanatory diagram of a basic configuration of a continuous coating apparatus for continuously coating cellulose acetate on a polylactic acid film.
FIG. 3 is a sectional view showing an example of a split mold for explaining a shaping method using a mold using the cellulose adhesive and the coating agent of the present invention (hatching is omitted).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Decompression container 2 Heater 8 Heating jacket 12 Solvent recovery unit 13 Solvent condensation unit 14 Dehydration unit 16 Solvent recovery container 19 Continuous coating device

Claims (7)

A cellulose ester-based adhesive or a composition comprising an adhesive or coating composition obtained by dissolving a binder composed of a cellulose ester in a lactic acid ester, after application, heating and evaporating the lactic acid ester under reduced pressure to solidify the binder. Composition for coating. The cellulose ester-based adhesive or coating composition according to claim 1, wherein the cellulose ester is at least one selected from cellulose acetate and nitrocellulose. 3. The cellulose ester adhesive or coating composition according to claim 1, wherein the lactate is ethyl lactate. Polylactic acid and cellulose ester in which a coating composition obtained by dissolving a binder composed of cellulose ester in lactic acid ester is coated on a polylactic acid film or sheet and heated under reduced pressure to improve the surface heat resistance of the polylactic acid molded product. A laminate comprising: After applying a bonding or coating composition obtained by dissolving a binder composed of a cellulose ester in a lactate ester, the lactate ester is evaporated by applying reduced pressure under heating, and the lactate ester vapor is cooled and recovered by cooling. Of recovering lactic acid esters from waste. A decompression container, and a lactate ester recovery device, wherein the decompression container has a container heating means in at least a part of the container, and a bonding or coating composition in which a binder made of cellulose ester is dissolved in the lactate ester inside the container. A lactate ester recovery device, comprising a cooling device for cooling and recovering lactate ester vapor, the cellulose ester-based composition interposed between the vacuum container and a vacuum pump. A device that recovers lactate from materials. The apparatus for recovering a lactate ester from a cellulose ester-based composition according to claim 6, further comprising a dehydration apparatus for passing the lactate ester vapor or the lactic acid condensate through a dehydrating agent packed bed.

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