JP3261452B2 - Biodegradable plastic laminate and surface processing method for biodegradable plastic molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable plastic laminate and a method for processing the surface of a molded biodegradable plastic.

[0002]

2. Description of the Related Art Biodegradable plastics are composed of a biodegradable polymer, and this kind of polymer is a series of macromolecules that are digested and decomposed by microorganisms existing in soil when buried in soil or the like. It is. The polymer having a biodegradable function contains a structural portion containing oxygen such as a hydrophilic ether bond or an ester bond which is digested in the polymer. Aliphatic hydrocarbon-based polymers having such a structure are generally known as biodegradable polymers.

[0003] When a biodegradable polymer is brought into contact with water, a liquid mixture thereof, or water vapor for a certain period of time, it absorbs moisture or absorbs moisture. In spite of this, a sudden decrease in mechanical properties such as breaking strength may be caused. Therefore, in the case of a biodegradable polymer, when the molded article is in use, it is necessary to take measures to prevent the mechanical properties from suddenly lowering based on the property of hydrophilicity.

[0004] As a measure for this, means for coating the surface of a molded article or the like with a hydrophobic layer is employed. In general, it is known that the coating means can be formed as a polymer thin film directly on the surface of a polymer or plastic molded product by plasma polymerizing an organic monomer gas. It is known that a surface coated with a plasma-polymerized thin film using a fluorine-based compound exhibits hydrophobicity. Therefore, in a process for imparting hydrophobicity, plasma treatment with a fluorine-based compound is performed. Coating formation by polymerization is effective. However, monomers containing elemental fluorine generally have low polymerization ability due to the dissociation of elemental fluorine, so it is difficult to polymerize and deposit as a polymer film. Further, it is impossible to use a saturated fluorine compound such as perfluoromethane or perfluorohexane for polymerization. Originally, since these substances have the property of decomposability, they are not suitable for polymerization, as can be seen from being used as an etching source. Further, a plasma polymerized thin film made of a fluorine-based compound has a problem that mechanical strength is poor and cracking occurs, so that the film is easily peeled off from the substrate surface. Therefore, even if a plasma polymerized film of a conventionally known fluorine-based compound can be formed, a satisfactory result cannot be obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable polymer laminate which can prevent a decrease in mechanical strength of a biodegradable plastic molded article due to the hydrophilic property of the biodegradable polymer. , Molded articles and methods for producing them.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on a polymer thin film coating treatment by plasma polymerization on the surface of a biodegradable plastic. The present invention has been completed by a method of providing an aqueous plasma copolymer thin film layer. Specifically, a certain amount of a silicon-based organic compound is mixed during plasma polymerization of a fluorine-based organic compound, and a coating treatment is performed with a polymer layer obtained by plasma-copolymerizing the mixed gas. Since such a plasma copolymer polymer layer has a cross-linked structure with high mechanical stability, coating with this layer can prevent the property of biodegradable plastic from being hydrophilic and provide sufficient mechanical properties. The present inventors have found that they have a specific strength and do not cause peeling due to cracking, and have completed the present invention.

According to the present invention, the following inventions are provided. Polylactic acid, polycaprolactone, poly (3-hydro
Xybutyrate), poly (butylene succinate),
Selected from the group consisting of starch and cellulose
Both are characterized by being a laminate formed by laminating a copolymer thin film composed of a fluorine-based organic compound containing a silicon-based compound at a fixed ratio on one or more biodegradable polymers. Biodegradable plastic laminate. The biodegradable plastic laminate according to the above, wherein the copolymer thin film is a copolymer thin film formed by plasma-polymerizing a fluorine-based organic compound containing a silicon-based compound at a certain ratio. The biodegradable plastic laminate according to the above, wherein the silicon-based compound is at least one kind or two or more kinds selected from the group consisting of silanes, siloxanes, and silazanes. The biodegradable plastic laminate as described above, which is a copolymer thin film in which the mixing ratio of the silicon-based compound to the fluorine-based organic compound is 0.1 to 0.8. The biodegradable polymer is a mixture containing one or more selected from the group consisting of polylactic acid, polycaprolactone, poly (3-hydroxybutyrate), poly (butylene succinate), starch and cellulose. The biodegradable plastic laminate according to the above, which is characterized in that: The biodegradable plastic laminate according to the above, wherein the biodegradable polymer is a plastic molded product processed into a film, a fiber, or a block. Polylactic acid, polycaprolactone, poly
(3-hydroxybutyrate), poly (butylene succinate)
Nart), starch and cellulose
At least one or more biodegradable polymers
The method is characterized in that a copolymer thin film is formed on the surface of a biodegradable polymer molded body by plasma polymerizing a mixture of a fluorine-based organic compound containing a silicon-based compound in a fixed ratio with respect to the molded body . Surface processing method of biodegradable plastic moldings. The surface of the biodegradable plastic molded article as described above, wherein the copolymer thin film is a copolymer thin film formed by plasma-polymerizing a fluorine-based organic compound containing a silicon-based compound at a certain ratio. Processing method. The method for processing a surface of a molded biodegradable plastic as described above, wherein the silicon-based compound is one or more selected from the group consisting of silanes, siloxanes, and silazanes. The surface processing method for a biodegradable plastic molded product according to the above description, wherein the copolymer thin film is a copolymer thin film in which a mixing ratio of a silicon-based compound to a fluorine-based organic compound is 0.1 to 0.8. The biodegradable polymer is polylactic acid, polycaprolactone, poly (3-hydroxybutyrate), poly (butylene succinate),
The surface processing method for a molded biodegradable plastic as described above, wherein the molded product is a mixture containing one or more selected from the group consisting of starch and cellulose. The method for processing a surface of a molded biodegradable plastic as described above, wherein the biodegradable polymer is a plastic molded product processed into a film, a fiber, or a block.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable plastic of the present invention
Constituting biodegradable polymers are polylactic acid and polycaprol
Couton, poly (3-hydroxybutyrate), poly (butyrate)
Chilensuccinate), from starch and cellulose
Consisting of one or more components selected from the group consisting of
It is a mixture of the above components. These biodegradable polymers constitute a plastic containing component polymers at various locations and various additives, and the polymer or plastic molded body can be a film, a sheet, a plate, a sphere, a line, or a cylinder. Various shapes such as shapes are used. The coating treatment of the present invention is possible on surfaces of any of these shapes.

In the present invention, a coating is applied to the surface of the polymer or plastic molded body. The coating method comprises adding a certain amount of a gaseous silicon-based compound to a gaseous fluorine-based organic compound, supplying the mixed gas into a plasma gas stream, performing plasma polymerization, and forming a molded body provided in the gas stream. Is intended to form a polymer thin film on the surface of the substrate.

[0010] The plasma polymerization of the present invention can be carried out using a conventionally known plasma polymerization apparatus having a plasma generator. The conditions for plasma polymerization are not particularly limited. In plasma polymerization, a plasma discharge is generated by applying a sufficient discharge output to a plasma generator. The organic monomer gas is supplied into an air stream generated by the generated plasma discharge. As a result, the organic monomer gas is activated, and the polymerization reaction is accelerated.
By installing a molded article to be coated at a site after the polymerization reaction has occurred, a desired coating treatment can be performed.

In order to generate plasma, radio waves of 13.56 MHz are usually applied under high vacuum conditions to generate plasma. A higher frequency wave can be used, and a lower frequency kilohertz-order audio wave can be used. Appropriate discharge output depends on conditions such as the pressure of the supplied monomer gas,
It is also affected by the shape of the polymerization apparatus. It is also possible to introduce helium gas into the reaction system and perform plasma discharge at a frequency on the order of kilohertz under normal pressure conditions, thereby performing plasma polymerization.

The fluorine-based organic compound used in the plasma polymerization, which is supplied into the plasma stream, is a hydrocarbon having an elemental fluorine, or a fluorine-substituted hydrocarbon, or a fluorinated carbon compound. Specifically, the following compounds can be mentioned. Perfluorohexane, perfluoroheptane, perfluoro-1,3
-Dimethylcyclohexane, hexafluorobenzene,
Pentafluorotoluene, 4-fluorinated ethylene and at least one or more compounds selected from the group consisting of these.

Among the fluorine compounds, the fluorine compounds having a skeleton having a saturated structure such as saturated tetrafluoromethane, perfluorohexane, perfluoroheptane and the like cannot be polymerized alone. However, there are some which can be used depending on the conditions even if they are not plasma-polymerized by themselves. The condition is the case where plasma polymerization is performed in the co-presence of a polymerizable monomer.For example, a silicon-based compound having high polymerizability is used as a silicon compound used as another component with respect to a fluorine-based compound. If they are made to coexist, they will copolymerize to give deposits, so that even the above compounds can be used.

The silicon compound to be added to the fluorine-based organic compound is a compound in which silicon is bonded to a hydrocarbon skeleton, and which evaporates at a temperature of up to about 50 ° C. under a high vacuum to become gaseous. If it is, it can be used as appropriate and is not particularly limited. Specifically, siloxane compounds such as hexamethyldisiloxane, tetramethyldisiloxane, hexamethylcyclosiloxane, and tetramethyldisiloxane, silane compounds such as hexamethyldisilane, and silazane compounds such as hexamethyldisilazane are used. Can be mentioned.

Some fluorine-based compounds have poor polymerizability or do not polymerize at all because of the high dissociation of fluorine constituting the fluorine-containing compound. On the other hand, the silicon-based organic compound generally shows high polymerizability. Therefore, in a reaction in a mixed gas system in which a monomer such as a silicon-based organic compound having a high polymerization activity coexists, the fluorine-based monomer is incorporated into this and copolymerization becomes possible. In the copolymer, the component of the fluorine-based compound is taken in, and a film-like substance having properties unique to the fluoropolymer is obtained. For copolymerization, generally any mixing ratio of both components is possible, but the mixing ratio (molar ratio) of the silicon compound to the fluorine organic compound is preferably 0.1 to 0.8, more preferably 0 to 0.8. The range of .1 to 0.6 is appropriate. If conditions outside of this range are adopted, satisfactory results cannot be obtained.

The polymerization conditions are affected not only by the discharge output but also by the pressure of the monomer gas in the reaction system. In order to perform plasma polymerization more effectively, the total partial pressure of the mixed gas comprising the raw material compounds is preferably introduced so as to be in the range of 1 to 10 Pascal, and the discharge power is applied within a certain range. And the gas must be activated.

In the plasma polymerization reaction in the method of the present invention, the radical species activated by the plasma serve as a growth point to start the reaction. In other words, the electrons generated under discharge collide with the gaseous organic compound, which dissociates the chemical bonds that make up this compound to generate radicals, and the generated gas-phase radicals recombine. Generally, a polymer having a crosslinked structure is formed. The copolymer thin film of the present invention,
The hydrophobic effect of fluorine is exerted in a state of being tightly fixed by the crosslinkable polymer of silicon, and a film having a desired function can be effectively formed. Such a crosslinked structure is dense and is useful for protecting the surface of the molded biodegradable plastic.

A polymer film made under low power gives a highly organic product film with a low degree of crosslinking. On the other hand, in the opposite case, a film having a high degree of cross-linking is provided, and when the degree of cross-linking is extremely increased, an inorganic structure is considered. Generally, 2 to 20
By supplying power in the range of 0 W, discharge occurs and plasma polymerization is enabled. In this case, the polymerization time is not particularly limited, and the length of the time may be appropriately selected depending on the desired thickness of the thin film to be formed. Further, the thickness of the coating layer of the polymer thin film can be changed by adjusting the supply amount of the monomer used for the plasma polymerization or the time of the polymerization.

In the present invention, the thickness of the polymer thin film to be coated is not particularly limited, and there is no particular problem as long as it can function as a protective layer. However, from the original purpose of controlling the degradability of the biodegradable plastic by hydrophilicity by coating the biodegradable plastic molded body, the range of 0.1 μm to 10 μm is preferable. A thickness in this range can be said to be sufficient for the purpose. In addition, the biodegradable plastic does not impair the inherent property of biodegradability.

As described above, most of the polymers constituting the biodegradable plastic contain oxygen in the form of ethers, esters and the like. These groups are hydrophilic and are generally susceptible to the action of plasma, and are liable to be etched by the action of ultraviolet rays or radicals in the plasma, which breaks the bond chains. However, when an organic gas compound such as silicon is introduced, polymerization proceeds under the plasma, and a thin film is formed on the substrate, so that the plastic is stabilized by this layer. For this reason, unlike the case of the surface treatment using only an inorganic gas such as oxygen or nitrogen, the thin coating layer is not etched by the protective action and does not deteriorate.

[0021]

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

Example 1 A 0.3 mm thick polylactic acid sheet prepared by extrusion was placed in a Pyrex glass cylindrical reaction tube having an inner diameter of 4.4 cm and a length of 40 cm, and was previously vacuum-degassed. Thereafter, a mixed gas of perfluorofuran (hereinafter, referred to as PFF) having a gas pressure of 2.0 Pascal and hexamethyldisiloxane (hereinafter, referred to as HMSO) having a gas pressure of 2.0 Pascal was introduced through a precision valve. The mixture molar ratio of HMSO added at this time is about 0.495. In this mixed gas state, an inductively coupled plasma processing apparatus using radio waves of 13.56 MHz is used,
A polymerization reaction was performed by generating a plasma discharge at a power of 50 watts. By the treatment for 20 minutes, a copolymer layer formed by plasma polymerization having a thickness of about 1.25 μm was formed.
Measurement of the contact angle with water on the treated film resulted in an advancing contact angle of 102 degrees. This treatment could impart water resistance to the polylactic acid sheet.

Example 2 In the same manner as in Example 1, a gas pressure P of 3.0 Pa was applied.
A mixed gas consisting of FF and 2.0 Pascal HMSO was introduced. The mixture molar ratio of the HMSO added at this time was about 0.357. In this mixed gas state, 13.56
Using an inductively coupled plasma processing apparatus using a radio wave of MHz, a plasma discharge was generated at a power of 50 watts to perform a polymerization reaction on the polylactic acid sheet. After about 20 minutes of treatment, a copolymerized layer formed by plasma polymerization having a thickness of about 1.82 microns was formed. As a result of measuring the contact angle with water on the treated film, an advancing contact angle of 105 degrees was obtained, and it was revealed that the film had a surface with high hydrophobicity. By this treatment, the polylactic acid sheet could be processed with excellent water resistance.

Example 3 In the same manner as in Example 1, a P gas having a gas pressure of 4.0 Pascal was used.
A mixed gas composed of FF and 1.0 Pascal HMSO was introduced. The mixture molar ratio of HMSO added at this time was about 0.113. In this mixed gas state, 13.56
Using an inductively coupled plasma processing apparatus using a radio wave of MHz, a plasma discharge was generated at a power of 50 watts to perform a polymerization reaction on a polylactic acid sheet. 20
A minute treatment produced a copolymerized layer of about 1.20 microns thick by plasma polymerization. An advancing contact angle of 108 degrees was obtained on the treated film, and a water-resistant polylactic acid sheet having a highly hydrophobic surface was obtained.

Comparative Example 1 In the same manner as in Example 1, 4.0 Pascal of PFF gas was introduced, and plasma irradiation was performed under 50 watts.
However, when the reaction was carried out in the PFF-only system, the decomposition was prioritized, the polymer was not polymerizable, and the coating treatment on the polylactic acid sheet could not be performed substantially.

Example 4 Poly (butylene succinate) was prepared in the same manner as in Example 1.
A mixed gas (mixed molar ratio of about 0.5) of 2.0 Pascal HMSO and 2.0 Pascal pentafluorotoluene (hereinafter abbreviated as PFT) is placed on a molded film composed of a sheet (hereinafter referred to as PBS). A plasma polymerization process under 50 watts was used to obtain a film having a layer thickness of about 2.4 microns. By this treatment, a transparent laminated composite film having adhesiveness could be obtained. The contact angle of the obtained polymer film surface was 105 degrees, indicating hydrophobicity. The surface was found to be water resistant.

Comparative Example 2 In the same manner as in Example 2, 4.0 Pascal of PFT gas was introduced, and plasma polymerization was carried out under an atmosphere of this gas alone at 50 watts. Since this monomer was composed of an unsaturated benzene skeleton, polymerization proceeded differently from the system of PFF alone in Comparative Example 1, and a thin film was formed on the sheet. However, in this case, although the hydrophobicity of the surface of the coating layer was recognized, cracking gradually occurred from the surface when the coating layer was brought into contact with water, and a tendency of peeling was observed, so that the treatment effect was significantly deteriorated. In addition, brown coloring was observed in the polymer coating layer. Therefore, when this monomer was polymerized alone, it was not suitable as a durable coating.

Example 5 In the same manner as in Example 2, 2.0 Pascal of hexamethyldisilane (hereinafter referred to as HMS) was placed on a PBS sheet.
And a molar ratio of 0.5 with a 2.0 Pascal PFF gas introduced.
10 under the mixed monomer gas atmosphere of 2 and the output of 40 W
Plasma copolymerization was performed for minutes. By this polymerized thin film, P
A coating consisting of a layer about 0.66 microns thick was formed on the BS sheet. This composite sheet exhibited water repellency and did not peel even in boiling water.

Example 6 In the same manner as in Example 5, 2.0 pascal of hexamethyldisilazane (hereinafter, referred to as HMSZ) was introduced, and a molar ratio of 2.0 Pascal of PFT gas to 0.1 Pascal was used. 51
Was subjected to plasma copolymerization in a mixed gas atmosphere. A coating thin film having a thickness of 1.07 μm was formed on the PBS sheet by a treatment for 10 minutes. The contact angle of water on the surface of the film obtained by this treatment was 103 degrees, indicating hydrophobicity.

[0030]

According to the present invention, it is possible to impart water repellency, water resistance and durability by coating a thin film on a biodegradable polymer. That is, when a fluorine-based compound is used alone, a polymerized thin film cannot be obtained, or even if it is obtained, it may cause cracking or the like and peel off. The present invention can solve these problems. A thin film coating treatment with a plasma copolymer consisting of a silicon compound contained in a fixed proportion of these fluorine-based organic compounds can adhere to the surface of the biodegradable plastic molded body. -It can impart functions such as water resistance and durability.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-221240 (JP, A) JP-A-62-111739 (JP, A) JP-A-59-1505 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (12)

(57) [Claims] 1. Polylactic acid, polycaprolactone, poly (3
-Hydroxybutyrate), poly (butylene succinator)
G), selected from the group consisting of starch and cellulose
To at least one or two or more biodegradable polymers ,
A biodegradable plastic laminate characterized by being a laminate formed by laminating a copolymer thin film comprising a fluorine-based organic compound containing a silicon-based compound at a fixed ratio. 2. The green thin film according to claim 1, wherein the copolymer thin film is formed by plasma polymerizing a fluorine-based organic compound containing a silicon-based compound at a certain ratio. Degradable plastic laminate. 3. The method according to claim 1, wherein the silicon-based compound is at least one compound selected from the group consisting of silanes, siloxanes, and silazanes.
3. The biodegradable plastic laminate according to any one of claims 1 to 2. 4. The copolymer thin film according to claim 1, wherein the mixing ratio of the silicon compound to the fluorine organic compound is 0.1 to 0.8. The biodegradable plastic laminate according to any one of the above items. 5. The biodegradable polymer is at least one or more selected from the group consisting of polylactic acid, polycaprolactone, poly (3-hydroxybutyrate) , poly (butylene succinate), starch and cellulose. The biodegradable plastic laminate according to any one of claims 1 to 4, wherein the laminate is a mixture containing the biodegradable plastic. 6. The biodegradable polymer is in the form of a film, a fiber,
The biodegradable plastic laminate according to any one of claims 1 to 5, wherein the laminate is a plastic molded body processed into a block shape. 7. Polylactic acid, polycaprolactone, poly (3
-Hydroxybutyrate) , poly (butylene succinate), at least one or more biodegradable polymer moldings selected from the group consisting of starch and cellulose, containing a silicon-based compound at a certain ratio. A method of processing a surface of a biodegradable plastic molded product, comprising forming a copolymer thin film on the surface of a biodegradable polymer molded product by subjecting a mixture comprising a fluorine-containing organic compound to plasma polymerization. 8. The green thin film according to claim 7, wherein the copolymer thin film is formed by plasma-polymerizing a fluorine-based organic compound containing a silicon-based compound at a predetermined ratio. Surface processing method for degradable plastic moldings. 9. The method according to claim 7, wherein the silicon compound is one or more selected from the group consisting of silanes, siloxanes, and silazanes.
9. The surface processing method for a biodegradable plastic molded article according to any one of items 1 to 8. 10. The copolymer thin film according to claim 7, wherein the mixture ratio of the silicon compound to the fluorine organic compound is 0.1 to 0.8. Surface processing method of a molded biodegradable plastic. 11. The biodegradable polymer is polylactic acid or polycap.
Lolactone, poly (3-hydroxybutyrate), poly
(Butylene succinate), a mixture containing at least one selected from the group consisting of starch and cellulose.
Item 14. The method for surface treating a biodegradable plastic molded article according to any one of the above items. 12. The method for processing a surface of a biodegradable plastic molded product according to claim 7, wherein the plastic molded product is a film, a fiber, or a block.