JP2009274745A - Polyester resin container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin container provided with a coating film excellent in gas barrier characteristics, adhesive characteristics to a resin substrate and processability. <P>SOLUTION: This polyester resin container is provided with a thin layer coating film containing Si on the resin substrate on its inner face side. The thin layer coating film is provided with a bottom coating film layer and a top coating film layer formed by PICVD method on the resin substrate. The bottom coating film layer contains Si, C and O, is provided with a thickness of at least 7 nm. The Si and O content in the bottom coating film layer increases while C content in the layer decreases toward the part brought into contact with the top coating film layer from the surface of the resin substrate in elementary composition by the HR-RBS depth profile analysis and the content of Si in the area of at least 5 nm thickness from the surface of the resin substrate is 14 atom% or less. The top coating film layer contains Si, C and O and is provided with a thickness in a range of 5-15 nm. The atom number ratio between O relative to Si is between 2.1-2.5 and the content of C is 15 atom% of less in elementary composition by the HR-RBS depth profile analysis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyester resin container provided with a thin layer film containing silicon as a film layer having gas barrier properties on a resin base on the inner surface side of the container.

  Conventionally, as a beverage container, a container blow-molded using a polyester resin such as polyethylene terephthalate is known. The blow molded container made of the polyester resin (hereinafter abbreviated as a polyester resin container) is lightweight, excellent in transparency, and has sufficient strength, and is therefore awarded for beverage containers. On the other hand, the polyester resin container generally cannot be said to have sufficient gas barrier properties, and when the beverage as a content contains carbon dioxide gas, the carbon dioxide gas is released to the outside of the container, or conversely, oxygen in the atmosphere is released. Since it penetrates into the container, there is a problem of deteriorating the quality of the contents.

  In order to solve the above problem, for example, a polyester resin container having an amorphous carbon film as a film having a gas barrier property on a resin base on the inner surface side of the container has been proposed (see, for example, Patent Document 1). In recent years, the polyester resin container having a silicon-containing film formed by a chemical vapor deposition (CVD) method and having excellent transparency has been proposed (see, for example, Patent Document 2).

However, even in a polyester resin container provided with the coating film having the gas barrier property, the gas barrier property is not sufficient, and further improvement is desired. In addition, in the polyester resin container, it is desired that the film having the gas barrier property is excellent in adhesion to the resin base material and workability from the viewpoint of handling in the process of filling and transporting the contents. .
JP 2004-142743 A JP-T-2005-531688

  In view of such circumstances, an object of the present invention is to provide a polyester resin container provided with a coating having excellent gas barrier properties, adhesion to a resin base material, and workability on a resin base material on the inner surface side of the container. To do.

  In order to achieve such an object, the polyester resin container of the present invention is a polyester resin container provided with a thin film containing silicon on a resin base on the inner surface side of the container. A lower coating layer formed by a PICVD (plasma impulse chemical vapor deposition) method using an organosilicon compound on the material, and an upper coating layer formed by a PICVD method on the lower coating layer; The lower coating layer includes silicon, carbon, and oxygen, has a thickness of at least 7 nm, and has an elemental composition by depth profile analysis using high-resolution Rutherford backscattering spectroscopy. While the content of silicon and oxygen increases toward the part in contact with the coating layer, the content of carbon decreases and the surface of the resin substrate In a region having a thickness of at least 5 nm, the silicon content is in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region, and the upper coating layer contains silicon, carbon, and oxygen. And having a thickness in the range of 5 to 15 nm and an elemental composition by depth profile analysis using high-resolution Rutherford backscattering spectroscopy, wherein the ratio of the number of oxygen atoms to the number of silicon atoms is 2.1 to 2.5 The carbon content is in the range of 15 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the upper coating layer.

  In the polyester resin container of the present invention, the thin layer coating includes a lower coating layer formed on the resin substrate and an upper coating layer formed on the lower coating layer. Here, the lower coating layer and the upper coating layer are both formed by the PICVD method, and the lower coating layer acts as a primer for firmly bonding the upper coating layer to the resin substrate, and the upper coating layer Acts as a gas barrier coating.

  The lower coating layer is a coating containing silicon, carbon, and oxygen, and needs to have a thickness of at least 7 nm in order to function as the primer. When the thickness of the lower coating layer is less than 7 nm, it is not possible to obtain an effect of favorably bonding the upper coating layer to the resin base material.

  The lower coating layer has an elemental composition by depth profile analysis (hereinafter abbreviated as HR-RBS depth profile analysis) using high-resolution Rutherford backscattering spectroscopy, and is applied from the resin substrate surface to the upper coating layer. While the content of silicon and oxygen increases toward the contacting portion, the carbon content decreases, and the silicon content is included in the region in a region having a thickness of at least 5 nm from the resin substrate surface. The total amount of silicon, carbon, and oxygen is in the range of 14 atomic% or less. In other words, the closer to the resin substrate surface, the more the carbon content increases to an organic composition, and the closer to the portion in contact with the upper coating layer, the more the silicon and oxygen content increases and the inorganic composition increases. It means having a composition.

  As a result, the lower coating layer adheres firmly to the resin substrate itself by the organic composition in the vicinity of the resin substrate surface, and the inorganic composition in the vicinity of the portion in contact with the upper coating layer. Can firmly adhere to the upper coating layer. Therefore, the lower coating layer is interposed between the upper coating layer and the resin base material, and acts as a primer that adheres the thin layer coating to the resin base material while firmly adhering to both. The thin film can be provided with excellent workability. In the lower coating layer, when the silicon content in the region having a thickness of at least 5 nm from the surface of the resin substrate exceeds 14 atomic% with respect to the total of silicon, carbon, and oxygen contained in the region, the thin layer The primer effect of imparting processability and adhesion to the coating becomes insufficient, and further, the coating of the upper coating layer is hardly formed on the inner surface of the container, and the gas barrier property is lowered.

  On the other hand, the upper coating layer is a coating containing silicon, carbon, and oxygen, and needs to have a thickness in the range of 5 to 15 nm in order to function as the gas barrier coating. If the thickness of the upper coating layer is less than 5 nm, the required gas barrier property cannot be obtained, and if it exceeds 15 nm, the adhesion and workability deteriorate, and in the filling, transporting, and subsequent handling steps of the contents, etc. When deformation processing is applied to the container, problems such as a crack in the thin film and a decrease in gas barrier properties occur.

  Further, the upper coating layer has an elemental composition by HR-RBS depth profile analysis, the ratio of the number of oxygen atoms to the number of silicon atoms is in the range of 2.1 to 2.5, and the carbon content is the upper coating layer. Is in the range of 15 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in. In other words, this means that the upper coating layer has a more inorganic composition, and the upper coating layer can obtain excellent gas barrier properties due to its inorganic composition.

  The upper coating layer has an elemental composition by HR-RBS depth profile analysis, and the ratio of the number of oxygen atoms to the number of silicon atoms is less than 2.1, or the carbon and silicon contained in the upper coating layer When it exceeds 15 atomic% with respect to the total of oxygen and oxygen, the inorganic property of the inorganic composition is reduced, and the required gas barrier property cannot be obtained. In the polyester resin container of the present invention, when the upper film is formed by the PICVD method, the elemental composition is determined by HR-RBS depth profile analysis, and the carbon content is silicon, carbon and oxygen contained in the upper coating layer. It is difficult to form a film having a ratio of the number of oxygen atoms to the number of silicon atoms of more than 2.5 with respect to the total of

  According to the present invention, according to the above-described configuration, it is possible to obtain a polyester resin container provided with a film having excellent gas barrier properties, adhesion to the resin substrate, and workability on the resin substrate on the inner surface side of the container. .

  In the present invention, the lower coating layer has an elemental composition by depth profile analysis using X-ray photoelectron spectroscopy, and the silicon in the lower coating layer is directed from the surface of the resin substrate toward the portion in contact with the upper coating layer. It is preferable to provide a coating composition in which the oxygen bonding ratio is gradually increased and the carbon bonding ratio is gradually decreased. When the lower coating layer has the above-described configuration, the content of silicon and oxygen increases from the surface of the resin substrate toward the portion in contact with the upper coating layer with an elemental composition according to HR-RBS depth profile analysis. On the other hand, the carbon content is reduced, and the silicon content is 14 atomic% with respect to the total of silicon, carbon, and oxygen contained in the region having a thickness of 5 nm or more from the resin substrate surface. It can be set as the structure used as the following ranges.

  In the present invention, the thin layer coating preferably has a ratio of the thickness of the upper coating layer to the thickness of the lower coating layer in the range of less than 2.0. More preferably, it is in the range. When the ratio of the thickness of the upper coating layer to the thickness of the lower coating layer exceeds 2.0, the required adhesion and workability may not be obtained in the thin film, and the polyester resin In the process of filling the container with the contents or transporting the polyester resin container, the thin film may peel off from the resin base material or cause a crack.

  Further, the gas barrier property of the thin film may be lowered when the ratio of the thickness of the upper coating layer to the thickness of the lower film layer is less than 0.4, and when the ratio exceeds 1.8, the required adhesion is obtained. And processability may not be obtained.

  Moreover, in this invention, it is preferable that the sum total of the thickness of the said upper coating layer and the said lower coating layer exists in the range of 12-35 nm. In this case, the thickness of the lower coating layer is set in the range of 7 to 30 nm. When the total thickness of the upper coating layer and the lower coating layer is less than 12 nm, the required thickness of the thin coating layer may not be sufficiently obtained, and when the thickness exceeds 35 nm. Adhesiveness and workability may not be obtained sufficiently.

  In the present invention, the thin film is formed by a PICVD method using an organosilicon compound as a film forming material. However, the thin film may be formed in a single step or may be formed in a plurality of steps. . The thin film is preferably formed by using the PICVD method to form the first silicon-containing film on the resin substrate using a mixture containing 0 to 15 mol of oxygen with respect to 1 mol of the organosilicon compound as the first step. Then, as a second step, a second silicon-containing film is formed on the first silicon-containing film by the PICVD method using a mixture containing 50 to 150 mol of oxygen with respect to 1 mol of the organosilicon compound. It is formed by forming.

  The first step and the second step may be performed continuously or intermittently. Further, the conditions of the PICVD method may be changed between the first step and the second step.

  Furthermore, the polyester resin container of the present invention is provided with a water-resistant coating layer such as an amorphous carbon coating and a hydrophobic organosilicon polymer coating on the upper coating layer, thereby providing excellent water resistance to the thin-layer coating. Since it can be provided and the contents in a wider pH range can be filled, it can be used as a container for more various contents.

  Next, embodiments of the polyester resin container of the present invention will be described in more detail.

  The polyester resin container of the present embodiment includes a thin layer film containing silicon on a resin base material on the inner surface side of a container obtained by blow molding a preform made of a polyester resin such as polyethylene terephthalate. Yes. In the polyester resin container, the thin film is formed by a PICVD (plasma impulse chemical vapor deposition) method.

  In the PICVD method, an untreated polyester resin container obtained by the blow molding is placed in a vacuum chamber, and the inner and outer surfaces of the untreated polyester resin container are respectively maintained at a predetermined degree of vacuum. By introducing the film-forming starting material into the inner surface of the untreated polyester resin container and generating a plasma by optimizing the output, waveform, and on / off time of the microwave, on the resin base material on the inner surface of the container The thin film is formed.

  Specifically, the formation of the thin film by the PICVD method can be performed as follows. First, the untreated polyester resin container is placed in a PICVD plasma processing chamber as a vacuum chamber. The plasma processing chamber is connected to a vacuum pump, and the inner surface side and the outer surface side of the untreated polyester resin container disposed inside can be decompressed freely.

Next, the air inside the untreated polyester resin container and the air outside the container disposed in the plasma processing chamber are removed by the vacuum pump, and the untreated polyester resin product in the plasma processing chamber is removed. The inner surface side and outer surface side of the container are each set to a predetermined degree of vacuum. The degree of vacuum on the inner surface side of the untreated polyester resin container is preferably 10 to 10 ⁻² Pa, for example. If the atmospheric pressure in the plasma processing chamber is less than 10 ⁻² Pa and the degree of vacuum is higher than the above range, it takes time to form a film. On the other hand, if the atmospheric pressure in the plasma processing chamber exceeds 10 Pa and the degree of vacuum is lower than the above range, the adhesion, workability, and gas barrier properties of the obtained film are deteriorated. Further, the degree of vacuum on the outer surface side of the untreated polyester resin container is such that the untreated polyester resin container is not deformed by a pressure difference with the inner surface side of the untreated polyester resin container, and plasma is generated. It is preferable to make it not.

  In the untreated polyester resin container disposed in the plasma processing chamber, a gas supply pipe is inserted from the mouth into the container. Therefore, next, the gaseous film forming starting material is introduced into the untreated polyester resin container through the gas supply pipe.

  Next, the film forming starting material is introduced from the gas supply pipe, while the inner surface side and the outer surface side of the untreated polyester resin container are maintained at the predetermined vacuum degree by the vacuum pump. Next, the thin film is formed on the resin base material on the inner surface side of the untreated polyester resin container by generating plasma in the state as described above.

  When a predetermined film is formed, the decompression by the vacuum pump is released, and the polyester resin container on which the thin film is formed is taken out from the plasma processing chamber.

  The PICVD method differs from the conventionally known PECVD method (plasma enhanced chemical vapor deposition) in terms of microwave output, waveform, and the like.

  According to the PICVD method, the output and waveform of the microwave for generating plasma can be controlled arbitrarily. Therefore, the plasma is generated in a pulse shape, and the coating film formed for each pulse is laminated in multiple layers. Can be formed. In addition, according to the PICVD method, the generation interval of the pulse can be arbitrarily controlled, and the formation of the thin film can be accurately controlled. The PICVD method has a higher output than the conventional PECVD method, and it is suitable to use a rectangular microwave.

  In the PICVD method, when the plasma during the pulse is not generated, it is possible to arbitrarily control the time for removing the side reaction product from the polyester resin container to the outside of the system, so that the plasma is generated. In some cases, the polyester resin container has few by-products and can supply a purer film-forming starting material gas. Therefore, according to the PICVD method, the pure film-forming starting material with a small amount of by-products is present in the vicinity of the substrate surface, and a uniform film is formed from the film-forming starting material. In addition, the film formation time can be shortened.

  Further, the PICVD method is suitable as a film forming means for the resin base material because the temperature can be easily controlled.

  In this embodiment, it is suitable to use an organic silicon compound as the film forming starting material used in the PICVD method. For example, silanes, alkoxysilanes, siloxanes, alkyldisiloxanes, silazanes, alkyldisilanes are used. Examples thereof include silazanes and organosilicon compounds such as silicon-containing compounds having a vinyl group. Examples of the silanes include monoalkyl silane, dialkyl silane, trialkyl silane, and tetraalkyl silane. Examples of the alkoxysilanes include monoalkoxysilane, dialkoxysilane, trialkoxysilane, and tetraalkylsilane. Examples of the alkyldisiloxanes include tetraalkyldisiloxane, hexaalkyldisiloxane, and hexamethyldisiloxane. Examples of the alkyldisilazane include tetraalkyldisilazane, hexaalkyldisilazane, hexamethyldisilazane, and the like.

  The film-forming starting material can be used by mixing one or more of the organosilicon compounds, and is preferably used in combination with oxygen. The film-forming starting material may be diluted with a rare gas such as argon or helium if desired.

  In this embodiment, first, as the film formation starting material, a mixture containing 0 to 15 moles of oxygen with respect to 1 mole of the organosilicon compound is used, and by the PICVD method, the inner surface side of the untreated polyester resin container is used. A first thin silicon-containing film is formed on the resin substrate. For example, hexamethyldisiloxane (HMDSO) can be used as the organosilicon compound for forming the first thin silicon-containing film.

  Next, as the film formation starting material, a mixture containing 50 to 150 mol of oxygen with respect to 1 mol of the organosilicon compound is used, and a second thin film is formed on the first thin silicon-containing film by the PICVD method. A layer silicon-containing coating is formed. As the organosilicon compound used at that time, for example, hexamethyldisilazane (HMDSN) can be used.

  The thin film layer composed of the first and second thin silicon-containing films formed as described above contains silicon, carbon, and oxygen as the lower film layer, and is at least 7 nm, preferably 7 to 30 nm. It has a thickness. At this time, the elemental composition of the thin coating layer can be analyzed by a known high-resolution Rutherford backscattering spectroscopy (HR-RBS) depth profile analysis.

  Next, HR-RBS depth profile analysis will be described. Rutherford backscattering spectroscopy (RBS method) is a method in which ions of light elements such as hydrogen and helium are accelerated at high speed and collide with a solid. The element after lithium on the periodic table is identified by utilizing the fact that helium ions are scattered backward.

  According to this RBS method, the composition and distribution in the depth direction of the solid can be known in a non-destructive manner for the elements after lithium on the periodic table contained in the solid.

  The HR-RBS method is a higher resolution of the RBS method, and the composition of elements after lithium on the periodic table with a resolution of sub-nm, for example, 0.2 to 1 nm level in the depth direction of the solid. Can be quantitatively analyzed. In this specification and the like, the analysis of the composition and distribution of elements in the depth direction of the thin film by the HR-RBS method is referred to as “HR-RBS depth profile analysis”.

  According to the HR-RBS depth profile analysis, the elemental composition of the lower coating layer increases the content of silicon and oxygen from the surface of the resin substrate toward the portion in contact with the upper coating layer, The content is reduced and the silicon content is in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region in a region having a thickness of at least 5 nm from the resin substrate surface. ing.

Further, the bonding state between silicon and carbon or the bonding state between silicon and oxygen in the lower coating layer can be known by depth profile analysis using X-ray photoelectron spectroscopy (XPS method). In the film of the present embodiment, the silicon atom (Si) is between Si (—O _0.5 ) (—C) ₃ and Si (—O ₀ ) between the oxygen atom (O) or the carbon atom (C). _.5 ) ₂ (—C) ₂ , Si (—O _0.5 ) ₃ (—C), and Si (—O _0.5 ) ₄ can be combined. And the bond energy of a silicon atom changes with said each bond state. Therefore, the composition of the four types of bonding states can be known by measuring the change in the bonding energy of silicon atoms in the depth direction of the thin film by depth profile analysis using the XPS method.

According to depth profile analysis using the XPS method, the content of the four bonding state in the lower coating layer, wherein in the resin substrate _{side, Si (-O 0.5) (-} C) 3, Si (-O _0.5 ) ₂ (-C) ₂ , Si (-O _0.5 ) ₃ (-C), Si (-O _0.5 ) ₄ are in this order. When it comes close to the part in contact with, Si (-O _0.5 ) ₄ , Si (-O _0.5 ) ₃ (-C), Si (-O _0.5 ) ₂ (-C) ₂ , _{Si (-O 0.5) (- C} ) a _third order. That is, in the lower coating layer, the oxygen bonding ratio gradually increases in the bonding structure of oxygen and carbon bonded to silicon in the lower coating layer from the surface of the resin substrate toward the portion in contact with the upper coating layer. In addition, the coating composition is such that the carbon bonding ratio gradually decreases.

  The lower coating layer having the above structure has an organic composition with an increase in the carbon content as it approaches the resin substrate surface, and the silicon and oxygen content increases as it approaches the portion in contact with the upper coating layer. It has an inorganic composition. As a result, the lower coating layer adheres firmly to the resin substrate itself by the organic composition in the vicinity of the resin substrate surface, and the inorganic composition in the vicinity of the portion in contact with the upper coating layer. Can firmly adhere to the upper coating layer. Therefore, the lower coating layer can be interposed between the upper coating layer and the resin base material to firmly bond both, and can act as a primer that adheres the thin layer coating to the resin base material. The thin layer coating can be provided with excellent processability.

  Next, the upper coating layer formed as described above contains silicon, carbon, and oxygen, has a thickness of 5 to 15 nm, and has an elemental composition according to HR-RBS depth profile analysis with respect to the number of silicon atoms. The ratio of the number of oxygen atoms is in the range of 2.1 to 2.5, and the carbon content is in the range of 15 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the upper coating layer. . As a result, the upper coating layer has a more inorganic composition, and an excellent gas barrier property can be obtained by the inorganic composition.

  In the polyester resin container according to the present embodiment, the thin layer coating has a ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer of less than 2.0. For example, it is in the range of 0.4 to 1.8. Here, according to the HR-RBS depth profile analysis, the thickness (T2) of the upper coating layer is a region in which the carbon content is 15 atomic% or less with respect to the total of silicon, carbon, and oxygen. Although it can be grasped satisfactorily, the error becomes large with respect to the thickness (T1) of the lower coating layer. Therefore, in this embodiment, the thickness (Ttotal) of the entire thin film is measured with a transmission electron microscope, and the difference (Ttotal−T2) between this and the thickness (T2) of the upper film layer is measured. Is the thickness (T1) of the lower coating layer. The total thickness (Ttotal) of the thin layer coating is, for example, in the range of 12 to 35 nm as the sum of the thickness (T2) of the upper coating layer and the thickness (T1) of the lower coating layer.

  Moreover, the polyester resin container of this embodiment includes a water-resistant coating layer on the thin coating layer. The water resistant coating layer is made of, for example, an amorphous carbon coating, a silicon-containing coating, or the like. When the water-resistant coating layer is a silicon-containing coating, for example, it is preferably a silicon-containing polymer coating having a relatively high carbon content formed by the PICVD method. The silicon-containing polymer film has, for example, a carbon content of 20 to 55 atomic%, a silicon content of 25 to 32 atomic%, and a film thickness in the range of 5 to 30 nm. The water-resistant film may be a single layer or a multilayer.

  Next, examples and comparative examples of the present invention are shown.

In this example, a polyethylene terephthalate resin preform was first blow-molded to obtain a 400 ml PET bottle. Next, the PET bottle as an untreated container is placed in a PICVD plasma processing chamber (vacuum chamber), and air on the inner surface side and outer surface side of the untreated container is removed with a vacuum pump. The degree of vacuum on the inner surface side was a degree of vacuum in the range of 10 to 10 ⁻² Pa. Next, hexamethyldisiloxane (HMDSO) is used as a starting material for forming a gaseous film from the mouth of the untreated container disposed in the plasma processing chamber through a gas supply pipe to the inside of the untreated container. While introducing a mixture containing 3 to 10 moles of oxygen with respect to 1 mole, the plasma is generated in a pulse form by a 2.45 GHz square wave microwave while maintaining the pressure in the plasma processing chamber at the vacuum level. A silicon-containing thin layer coating was formed.

  Next, hexamethyldisilazane (as a starting material for forming a gaseous film) is introduced into the interior of the untreated container from the mouth of the untreated container disposed in the plasma processing chamber through a gas supply pipe. (HMDSN) While introducing a mixture containing 80 to 120 moles of oxygen with respect to 1 mole, the plasma was pulsed by 2.45 GHz rectangular microwaves while maintaining the pressure on the inner surface of the untreated container at the vacuum level. The film was generated a predetermined number of times to form an additional film. As a result, a lower coating layer containing silicon, carbon, and oxygen is provided as a thin coating on the resin base on the inner surface side of the untreated container, and silicon, carbon, and oxygen are contained on the lower coating layer. A plastic bottle with an upper coating layer was obtained.

  Next, for the PET bottle obtained in this example, the flat surface of the body was selected, and the thickness of the thin film was measured by a transmission electron microscope as the sum of the lower film layer and the upper film layer. However, the thickness of the entire thin layer coating was 18 nm.

Next, about the PET bottle obtained in the present Example, the atomic composition of the said lower coating layer and the said upper coating layer was measured by HR-RBS depth profile analysis. The HR-RBS depth profile analysis was performed using HRBS500 (trade name) manufactured by Kobe Steel Co., Ltd. as a measuring instrument and measurement conditions of incident ion species He ⁺ and incident ion energy of 450 keV. The results are shown in FIG.

In the chart obtained by the HR-RBS depth profile analysis, the horizontal axis indicates the surface density of the number of atoms per unit area (number of atoms / cm ² ), and FIG. 1 shows the surface density as the coating density (g / cm ² ). It is converted into the depth (nm) from the coating surface by dividing by ³ ). Furthermore, in order to reduce the error due to the depth from the coating surface, in FIG. 1, the thickness of the region with a carbon content of 15% or less, which is a range with high depth accuracy, is set to the thickness of the upper coating layer (T2). And the difference between the thickness (Ttotal) of the thin film and the thickness of the upper film (T2) measured by the transmission electron microscope was defined as the thickness (T1) of the lower film.

  From FIG. 1, the upper coating layer has a thickness of 8 nm, and the silicon atom (Si) content is in the range of 26 to 29 atomic% with respect to the total of silicon, carbon and oxygen contained in the upper coating layer. It is clear that the content of carbon atoms (C) is in the range of 4 to 15 atomic% and the ratio of the number of carbon atoms to the number of silicon atoms (Si / C) is in the range of 2.2 to 2.4. is there.

  The lower coating layer has a thickness of 10 nm, and the content of silicon and oxygen decreases while the content of silicon and oxygen increases from the resin base material surface of the PET bottle toward the portion in contact with the upper coating layer. It is clear that it has a composition. Further, in the lower coating layer, the silicon content is in a range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region having a thickness of 6 nm from the surface of the resin substrate. ing.

  In the PET bottle obtained in this example, the ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer was 0.8.

Next, with respect to the PET bottle obtained in this example, the change in the binding energy of silicon atoms in the lower coating layer and the upper coating layer was measured by depth profile analysis using X-ray photoelectron spectroscopy, and each bond The composition of the silicon atom in the state was determined. In the X-ray photoelectron spectroscopy (XPS method), ESCA-3400 (trade name) manufactured by KARATOS was used as a measuring instrument, and a silicon analysis method with different bonding states was performed by a publicly known method. The results are shown in FIG. In FIG. 2, each bonding state of silicon atoms is represented by A: Si (—O _0.5 ) (— C) ₃ , B: Si (—O _0.5 ) ₂ (—C) ₂ , C: Si. _{(-O 0.5) 3 (-C)} , D: Si (-O 0.5) shown as _4.

  From FIG. 2, the content of each of the four bonded states in the lower coating layer is in the order of A> B> C> D on the resin base material side. It is clear that when it is close to the portion in contact with the layer, the order is reversed and D> C> B> A. That is, in the lower coating layer, the oxygen bonding ratio gradually increases in the bonding structure of oxygen and carbon bonded to silicon in the lower coating layer from the surface of the resin substrate toward the portion in contact with the upper coating layer. It is clear that the coating composition is such that the carbon bonding ratio gradually decreases.

  In the PET bottle obtained in the present example, the thin film composed of the lower film layer and the upper film layer is firmly adhered to the surface of the base material and has excellent adhesiveness, and against deformation of the bottle. Excellent workability.

  Next, the oxygen permeability of the PET bottle obtained in this example and the untreated container was measured. The oxygen permeability was measured under the conditions of 22 ° C. and 60% RH using OX-TRAN 2/21 (trade name) manufactured by MOCON as a measuring instrument.

As a result, the gas barrier property (oxygen permeability) of the untreated container alone is 0.04 (ml / pg / day), whereas the PET bottle obtained in this example has 0.003 (ml / kg). pkg / day) and had an excellent gas barrier property.
[Comparative Example 1]
In this comparative example, except that the film formation conditions by the PICVD method were adjusted so that the total thickness of the thin film was 19 nm and the thickness of the upper film layer was 4 nm, the same as in Example 1, A PET bottle having a lower coating layer containing silicon, carbon, and oxygen on the substrate on the inner surface side of the untreated container and an upper coating layer containing silicon, carbon, and oxygen on the lower coating layer was obtained.

  In the PET bottle obtained in this comparative example, the thickness of the lower coating layer obtained in exactly the same manner as in Example 1 is 15 nm. Among these, silicon in a region having a thickness of 6 nm from the resin substrate surface. The content was in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region. The ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer was 0.27.

As a result, in the PET bottle obtained in this comparative example, the thin layer coating is excellent in adhesion to the substrate surface and processability against deformation of the bottle, but has a gas barrier property (oxygen permeability). Of 0.02 (ml / pg / day) was insufficient.
[Comparative Example 2]
In this comparative example, in the film formation by the PICVD method using the same apparatus as in Example 1, the amount of oxygen with respect to 1 mol of hexamethyldisilazane (HMDSN) as a gaseous film formation starting material is 80 to 110 mol. Using the mixture, the degree of vacuum on the inner surface of the untreated container is set to a degree of vacuum in the range of 10 to 10 ⁻² Pa, plasma is generated in a pulsed manner by 2.45 GHz rectangular microwaves, and the total thickness of the thin film is 13 nm. And adjusting the conditions so that the thickness of the upper coating layer is 7 nm, and having a lower coating layer containing silicon, carbon, and oxygen on the resin substrate on the inner surface side of the untreated container, A PET bottle having an upper coating layer containing silicon, carbon, and oxygen on the lower coating layer was obtained.

  In the PET bottle obtained in this comparative example, the thickness of the lower coating layer obtained in exactly the same manner as in Example 1 is 6 nm, and among these, silicon in the region of 4 nm thickness from the resin substrate surface. The content was in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region. The ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer was 1.1.

As a result, in the PET bottle obtained in the present comparative example, the thin film is uniform because the thickness (T1) of the lower film layer is thin and the adhesion to the substrate surface is insufficient. A gas barrier property (oxygen permeability) measured in exactly the same manner as in Example 1 was 0.02 (ml / pg / day), which was insufficient.
[Comparative Example 3]
In this comparative example, in the film formation by the PICVD method, as a gaseous film formation starting material, a mixture in which the amount of oxygen with respect to 1 mol of hexamethyldisilazane (HMDSN) is 80 to 110 mol is used, and the total thickness of the thin layer film Is exactly the same as Comparative Example 2 except that the conditions are adjusted so that the thickness of the upper coating layer becomes 18 nm, and silicon, carbon, and oxygen are formed on the substrate on the inner surface side of the untreated container. A PET bottle having a lower coating layer containing, and an upper coating layer containing silicon, carbon, and oxygen was obtained on the lower coating layer.

  In the PET bottle obtained in this comparative example, the thickness of the lower coating layer obtained in exactly the same manner as in Example 1 is 7 nm, and among these, silicon in a region of 3 nm thickness from the resin substrate surface. The content was in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region. The ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer was 2.6.

Next, the plastic bottle obtained in this comparative example is filled with a carbonated beverage as a content, and after capping, a heat treatment is performed at a temperature of 60 ° C. for 15 minutes, and then the content is removed to provide a gas barrier property. (Oxygen permeability) was measured. The gas barrier properties were measured in exactly the same way as in Example 1. As a result, in the PET bottle obtained in this comparative example, the gas barrier property of the thin layer coating was insufficient (0.01 (ml / pg / day)).
[Comparative Example 4]
In this comparative example, in the film formation by the PICVD method, the amount of oxygen with respect to 1 mol of hexamethyldisiloxane (HMDSO) is set to 30 to 50 mol, and the total thickness of the thin film becomes 18 nm, and the thickness of the upper film layer Except that the conditions were adjusted so as to be 8 nm, exactly the same as in Example 1, provided with a lower coating layer containing silicon, carbon and oxygen on the substrate on the inner surface side of the untreated container, A PET bottle having an upper coating layer containing silicon, carbon, and oxygen on the lower coating layer was obtained.

  The PET bottle obtained in this comparative example has a silicon atom (Si) content in the range of 26 to 29 atomic% relative to the sum of silicon, carbon and oxygen contained in the upper coating layer, and carbon atoms (C ) In the range of 16 to 25 atomic%, and the ratio of the number of carbon atoms to the number of silicon atoms (Si / C) was in the range of 2.2 to 2.4.

  Further, in the PET bottle obtained in this comparative example, the thickness of the lower coating layer obtained in exactly the same manner as in Example 1 is 10 nm, and among these, in the region having a thickness of 6 nm from the surface of the resin substrate. The silicon content was in the range of 14 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the region. Further, the ratio (T2 / T1) of the thickness (T2) of the upper coating layer to the thickness (T1) of the lower coating layer was 0.8.

  As a result, in the PET bottle obtained in this comparative example, the thin film is excellent in adhesion to the surface of the base material and workability against deformation of the bottle, but is exactly the same as in Example 1. The gas barrier property (oxygen permeability) measured in this manner was 0.02 (ml / pg / day) and was insufficient.

  In this example, instead of hexamethyldisiloxane (HMDSO), a mixture of hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSN) (HMDSO: HMDSN = 1: 1 (molar ratio)) was used. Except that the amount of oxygen relative to 1 mol of the mixture was changed to 2 to 10 mol, a lower coating layer containing silicon, carbon and oxygen was formed on the substrate on the inner surface side of the untreated container exactly as in Example 1. In addition, a PET bottle having an upper coating layer containing silicon, carbon, and oxygen on the lower coating layer was obtained.

  In the PET bottle obtained in the present example, the thin film composed of the lower film layer and the upper film layer is firmly adhered to the surface of the base material and has excellent adhesiveness, and against deformation of the bottle. Excellent workability. Moreover, the gas barrier property (oxygen permeability) of the PET bottle obtained in this example was 0.003 (ml / pg / day), and had an excellent gas barrier property.

  In this example, instead of hexamethyldisiloxane (HMDSO), a mixture of hexamethyldisiloxane (HMDSO) and tetramethyldisiloxane (TMDSO) (HMDSO: TMDSO = 3: 1 (molar ratio)) was used. Except that the amount of oxygen relative to 1 mol of the mixture was changed to 2 to 10 mol, a lower coating layer containing silicon, carbon and oxygen was formed on the substrate on the inner surface side of the untreated container exactly as in Example 1. In addition, a PET bottle having an upper coating layer containing silicon, carbon, and oxygen on the lower coating layer was obtained.

  In the PET bottle obtained in the present example, the thin film composed of the lower film layer and the upper film layer is firmly adhered to the surface of the base material and has excellent adhesiveness, and against deformation of the bottle. Excellent workability. Moreover, the gas barrier property (oxygen permeability) of the PET bottle obtained in this example was 0.003 (ml / pg / day), and had an excellent gas barrier property.

  In this example, a mixture of 1 mol of hexamethyldisiloxane (HMDSO) and 2 to 10 mol of oxygen was used as a starting material for forming a gaseous film on the upper coating layer of the PET bottle obtained in Example 1. A water content coating layer having a carbon content of 20 to 55 atomic% and a silicon content of 25 to 32 atomic% by a PICVD method and having a thickness of 10 nm is formed on the resin substrate on the inner surface side of the untreated container. A PET bottle comprising a lower coating layer containing carbon, oxygen and carbon, an upper coating layer containing silicon, carbon and oxygen on the lower coating layer, and further comprising the water-resistant coating layer on the upper coating layer Got.

  In addition to the performance of the PET bottle obtained in Example 1, the PET bottle obtained in this example has excellent water resistance and good gas barrier properties even when the liquidity of the content is close to neutral. Met.

The graph which shows the result of the HR-RBS depth profile analysis with respect to the polyester resin container of this invention. The graph which shows the result of the depth profile analysis by the X-ray photoelectron spectroscopy with respect to the polyester resin container of this invention.

Claims (7)

In a polyester resin container provided with a thin film containing silicon on the resin base on the inner surface side of the container,
The thin layer coating includes a lower coating layer formed by a PICVD method using an organosilicon compound on the resin substrate, and an upper coating layer formed by a PICVD method on the lower coating layer,
The lower coating layer includes silicon, carbon, and oxygen, has a thickness of at least 7 nm, and has an elemental composition by depth profile analysis using high-resolution Rutherford backscattering spectroscopy. While the silicon and oxygen contents increase toward the portion in contact with the coating layer, the carbon content decreases, and the silicon content is at least 5 nm thick from the resin substrate surface. 14 atomic percent or less of the total of silicon, carbon, and oxygen contained in the region,
The top coating layer includes silicon, carbon, and oxygen, has a thickness in the range of 5 to 15 nm, and has an elemental composition by depth profile analysis using high-resolution Rutherford backscattering spectroscopy. The ratio of the number of atoms is in the range of 2.1 to 2.5, and the carbon content is in the range of 15 atomic% or less with respect to the total of silicon, carbon, and oxygen contained in the upper coating layer. A polyester resin container.   The lower coating layer has an elemental composition obtained by depth profile analysis using X-ray photoelectron spectroscopy, and oxygen bonded to silicon in the lower coating layer from the surface of the resin substrate toward a portion in contact with the upper coating layer. 2. The polyester resin container according to claim 1, further comprising: a coating composition in which the oxygen bond ratio gradually increases and the carbon bond ratio gradually decreases in the carbon bond structure.   The ratio of the thickness of the said upper coating layer with respect to the thickness of the said lower coating layer exists in the range in which the said thin layer coating film is less than 2.0, The polyester resin product of Claim 1 or Claim 2 characterized by the above-mentioned. container.   The ratio of the thickness of the said upper coating layer with respect to the thickness of the said lower coating layer exists in the range of 0.4-1.8, The said thin layer coating film of Claim 1 or Claim 2 characterized by the above-mentioned. Polyester resin container.   5. The polyester according to claim 1, wherein the thin-layer coating has a total thickness of the upper coating layer and the lower coating layer in the range of 12 to 35 nm. Resin container. The thin-layer coating is a first step in which a first silicon-containing coating is formed on the resin substrate by the PICVD method using a mixture containing 0 to 15 moles of oxygen with respect to 1 mole of an organosilicon compound as a first step.
Next, as a second step, a second silicon-containing film is formed on the first silicon-containing film by the PICVD method using a mixture containing 50 to 150 mol of oxygen with respect to 1 mol of the organosilicon compound. The polyester resin container according to any one of claims 1 to 5, wherein the container is made of polyester resin.   The polyester resin container according to any one of claims 1 to 6, further comprising a water-resistant coating layer on the upper coating layer.

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