Method for separating foreign material from interlayer with foreign material attached, and device for separating foreign material from interlayer with foreign material attached

Abstract

To provide a method for separating a foreign material from an interlayer with foreign material attached, obtainable from a glass laminate, in a shorter time.SOLUTION: A method for separating a foreign material from an interlayer with foreign material attached, obtainable from a glass laminate having an interlayer includes a swelling step of swelling the interlayer piece with foreign material attached, obtainable from a glass laminate, with a swelling solvent, a dissolving step of dissolving polyvinyl butyral contained in the interlayer piece with foreign material attached, with a dissolving solvent, and a separation step of separating the foreign material and the polyvinyl butyral-containing solution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for separating foreign matter from a foreign matter-containing interlayer film, and an apparatus for separating foreign matter from a foreign matter-containing interlayer film. [Background technology]

[0002] In order to reuse unnecessary laminated glass, it is necessary to appropriately recover the glass sheets and the interlayer film used in the laminated glass. However, many laminated glasses in recent years contain foreign matter such as metal wires, and such foreign matter also adheres to the interlayer film obtained from the laminated glass. Since the presence of foreign matter can make it difficult to reuse the material, various studies have been conducted on technologies for separating the foreign matter from the interlayer film containing the foreign matter.

[0003] As a method for separating foreign matter from a foreign matter-containing interlayer film obtained from laminated glass, for example, Patent Document 1 discloses a method including a step of dissolving interlayer film pieces with glass particles attached thereto obtained from waste laminated glass in an organic solvent to obtain an interlayer film solution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-285042 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method described in Patent Document 1 is not practical because the process of dissolving the interlayer film pieces in an organic solvent alone takes more than one day.

[0006] In view of the above, an object of one aspect of the present invention is to provide a method for separating foreign matter from a foreign matter-containing interlayer film obtained from laminated glass in a shorter time. [Means for solving the problem]

[0007] In order to solve the above problems, a method according to one aspect of the present invention is a method for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass having an interlayer film, the method including: a swelling step of swelling a foreign matter-containing interlayer film piece obtained from the laminated glass with a swelling solvent; a dissolving step of dissolving polyvinyl butyral contained in the foreign matter-containing interlayer film piece with a dissolving solvent; and a separation step of separating the foreign matter from a solution containing the polyvinyl butyral.

[0008] An apparatus according to one embodiment of the present invention is an apparatus for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass having an interlayer film, and includes a swelling section that swells the foreign matter-containing interlayer film pieces obtained from the laminated glass with a swelling solvent, a dissolving section that dissolves polyvinyl butyral contained in the foreign matter-containing interlayer film pieces with a dissolving solvent, and a separation section that separates the foreign matter from a solution containing the polyvinyl butyral. Effect of the Invention

[0009] According to one aspect of the present invention, foreign matter can be separated in a shorter time from a foreign matter-containing interlayer film obtained from laminated glass. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of laminated glass, and the interlayer film with foreign matter to be treated according to an embodiment of the present invention originates from the laminated glass. [Diagram 2] FIG. 2 is a flow diagram of a method for separating foreign matter from a foreign matter-containing interlayer film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted.

[0012] [Laminated glass and interlayer film with foreign particles] The interlayer film with foreign matter to be treated in one embodiment of the present invention is obtained by crushing laminated glass or the like. First, laminated glass will be described with reference to Fig. 1. Fig. 1(a) is a plan view of laminated glass 1 as viewed from the vehicle interior side, Fig. 1(b) is a cross-sectional view taken along line II in Fig. 1(a), and Fig. 1(c) is an enlarged view of part II in Fig. 1(a). As shown in Fig. 1(b), laminated glass 1 has a structure in which a glass sheet 11 on the vehicle exterior side and a glass sheet 12 on the vehicle interior side are bonded together with an interlayer film 20 interposed therebetween.

[0013] The glass plates 11 and 12 used in the laminated glass 1 may be glass plates such as soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, etc. The glass plates are preferably formed by the float method. The glass plates 11 and 12 may be untempered or may be tempered glass that has been subjected to air-cooling tempering or chemical tempering treatment.

[0014] The intermediate film 20 contains polyvinyl butyral (PVB). In addition, the intermediate film 20 contains a plasticizer in addition to polyvinyl butyral (PVB), and therefore has excellent plasticity and flexibility. The plasticizer may be a phthalate ester, a phosphate ester, a fatty acid ester, a glycol derivative, or the like, and a specific example thereof is triethylene glycol di-2-ethylhexyl ester. Furthermore, the intermediate film 20 may contain a thermoplastic resin other than polyvinyl butyral (PVB), a resin other than a thermoplastic resin, an additive other than a plasticizer, or the like. The amount of polyvinyl butyral (PVB) contained in the intermediate film 20 may be 50% by mass or more and 90% by mass or less with respect to the total amount of the intermediate film 20. In addition, the amount of the plasticizer contained in the intermediate film 20 may be 10% by mass or more and 50% by mass or less with respect to the total amount of the intermediate film 20. As described above, since the intermediate film 20 is made of a highly flexible material, when obtaining an intermediate film piece from the intermediate film for the method according to the present embodiment, it is preferable to use cutting with a cutter or the like.

[0015] The thickness of the interlayer film 20 may be 0.6 mm or more and 1.6 mm or less. By having a thickness in this range, the strength of the laminated glass can be ensured and handling properties can be prevented from being impaired due to an excessive increase in thickness. The interlayer film piece treated by the method of the present embodiment can also have a thickness in the above range.

[0016] The laminated glass 1 illustrated in Fig. 1 is an automobile window glass in which an electric heating wire 30 is enclosed. Although the electric heating wires 30 are not shown in Fig. 1(a), as shown in Figs. 1(b) and (c), a plurality of electric heating wires 30 are arranged spaced apart from each other inside the laminated glass 1. The electric heating wire 30 is sandwiched between the glass sheet 12 on the vehicle interior side and a single layer of interlayer film 20, and is partially embedded in the interlayer film 20. Such an electric heating wire 30 is also connected to a bus bar 40 shown in Fig. 1(a) and the like to form a heating device such as a deicer or defogger.

[0017] The heating wire 30 may be a wire made of a metal such as tungsten, nickel-chromium, or iron-chromium. Of these, tungsten wire is often used because of its high electrical resistance and low thermal expansion coefficient. When the heating wire is a tungsten wire, the laminated glass 1 becomes a tungsten wire-laminated glass for automobiles, and the foreign matter is the tungsten wire.

[0018] When the laminated glass 1 is crushed, the heating wire 30 is not crushed together with the glass sheet, but is separated from the glass sheet while remaining attached to the interlayer film 20. Furthermore, even when the interlayer film with foreign matter is crushed to obtain interlayer film pieces with foreign matter, the heating wire 30 remains attached to the interlayer film pieces.

[0019] In this specification, the term "foreign matter" in "interlayer film with foreign matter" refers to a material other than the interlayer film that is attached to the surface of the interlayer film removed from the laminated glass or embedded in the interlayer film. Therefore, the foreign matter is not limited to tungsten wires or heating wires. For example, when a heat generating device, an antenna, a liquid crystal device, a light control device, an image projection layer, a light emitting layer, a photovoltaic layer, a heat reflecting layer, or the like is provided in the laminated glass, if the above-mentioned components are attached to the interlayer film obtained when the laminated glass is crushed, the components become foreign matter in the interlayer film with foreign matter and the interlayer film piece with foreign matter. In addition, when an antenna, a liquid crystal device, or the like is provided in the laminated glass before crushing, the above-mentioned foreign matter may be a resin (PET, etc.) with a metal pattern, a metal oxide pattern, or the like. Regardless of the type of foreign matter, the thickness of the foreign matter attached to the interlayer film or the interlayer film piece from the surface of the interlayer film or the interlayer film piece may be 10 μm or more and 500 μm or less. For example, when the foreign matter is a heating wire 30, the thickness of the heating wire may be the above-mentioned thickness.

[0020] As shown in Fig. 1(a), the laminated glass 1 may have a shielding layer 50, also called a black ceramic layer, formed on the periphery of the glass sheet 12 on the vehicle interior side. The shielding layer 50 serves to protect a sealant or the like for mounting and holding the laminated glass 1 to the vehicle body from ultraviolet rays or the like. The shielding layer 50 is preferably a layer formed by applying and firing a ceramic color paste, for example, black, gray, dark brown, or the like.

[0021] The laminated glass 1 to be treated in this embodiment is not limited to the automobile window glass exemplified in Fig. 1. It may be any laminated glass for automobiles, such as a front glass, rear glass, side glass, roof glass, or laminated glass for vehicles other than automobiles, such as a train, or laminated glass for buildings other than vehicles, as long as it contains a substance that may become a foreign object when the interlayer film is recycled.

[0022] [Method of separating foreign objects] One embodiment of the present invention is a method for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass as described above. FIG. 2 shows a flow diagram of a specific method according to this embodiment. The method according to this embodiment includes a swelling step (S20) in which the foreign matter-containing interlayer film pieces are swelled with a swelling solvent, a dissolving step (S30) in which the polyvinyl butyral contained in the foreign matter-containing interlayer film pieces is dissolved with a dissolving solvent, and a separation step (S40) in which the foreign matter and the solution containing polyvinyl butyral are separated from each other. The method according to this embodiment can be performed in a batch manner or a continuous manner. As shown in FIG. 2, the method according to this embodiment may further include a crushing step (S10) in which the foreign matter-containing interlayer film obtained by separating the interlayer film from the laminated glass is crushed to obtain the foreign matter-containing interlayer film pieces before the swelling step (S20). Each step will be described in more detail below.

[0023] <Crushing process (S10)> In the crushing step (S10), the interlayer film is first separated from the laminated glass. Specifically, for example, the laminated glass 1 shown in FIG. 1 is crushed by a crusher or the like, and the glass cullet attached to the interlayer film is separated by wet processing or the like. By crushing the laminated glass 1 and separating the glass cullet, the glass plates 11 and 12 are collected as glass cullet, and the interlayer film to which the foreign matter (the heating wire 30 in the example of FIG. 1) is attached can be taken out. In the crushing step (S10), such an interlayer film with foreign matter is further crushed to obtain interlayer film pieces with foreign matter. Since the interlayer film contains a plasticizer, it has low hardness and high flexibility. Therefore, cutting with a cutter or the like is preferably used as a method for crushing the interlayer film with foreign matter. Furthermore, by cutting with a cutter or the like, even if the foreign matter contained is a hard material that is difficult to crush, the foreign matter can be easily cut together with the interlayer film. An example of a method for crushing the interlayer film is a method in which the interlayer film is cut into a plurality of interlayer film pieces by passing the interlayer film through a pair of rolls having cutters on their surfaces. Specifically, a device such as a shredder can be used.

[0024] When the crushing step (S10) is performed by shredding using a pair of rolls, the shredding method may be a straight cut method in which shredding is performed along multiple cutting lines along one direction, or a cross cut method in which shredding is performed along multiple cutting lines along two or more intersecting directions. In the cross cut method, forces are simultaneously applied along the intersecting cutting lines to cut the interlayer film, so that even if the interlayer film is soft, interlayer film pieces can be easily obtained. The cross cut method may include a method called a micro cross cut method or a one cut cross method.

[0025] The interlayer film pieces with foreign matter obtained by the crushing step (S10) may not be completely flat, but may have a somewhat curved shape. In that case, the volume of the interlayer film pieces with multiple foreign matter will be somewhat large. The weight per unit volume of the interlayer film pieces with foreign matter will be somewhat small, and may be, for example, 800 g / L or less. This creates gaps between the interlayer film pieces, which facilitates the flow of the solvent in the subsequent swelling step (S20) and / or dissolution step (S30). This promotes the interaction between the interlayer film pieces and the solvent, allowing the swelling and / or dissolution of the interlayer film pieces to proceed more quickly. In addition, the weight per unit volume of the interlayer film pieces with foreign matter may be 200 g / L or more. This makes it possible to avoid the need for a large amount of solvent to immerse most of the interlayer film pieces with foreign matter, and prevents the concentration of the solution containing polyvinyl butyral obtained through the subsequent dissolution step (S30) from becoming excessively small. The volume of the interlayer film pieces with foreign matter can be adjusted by the thickness of the interlayer film, the shape and size of the interlayer film pieces with foreign matter, the method for crushing the interlayer film with foreign matter, etc.

[0026] The shape of the interlayer film piece with foreign matter is preferably a shape with acute apexes, such as a polygon such as a triangle, a rectangle, a pentagon, etc., in plan view, or in plan view when the interlayer film piece is curved and stretched flat. A shape with acute apexes allows the subsequent swelling step (S20) and / or dissolving step (S30) to proceed more quickly, enabling processing in a shorter time.

[0027] The area of ​​one interlayer film piece with a foreign object is preferably 1 mm2 or less in plan view, or in plan view when the interlayer film piece is curved and stretched flat. 2 More than 2500mm 2 Less than 4mm, more preferably 2 More than 100mm 2 By having an area in the above range, the subsequent swelling step (S20) and / or dissolving step (S30) can proceed more quickly, and the time and cost in the crushing step (S10) can be reduced.

[0028] The maximum length of one interlayer film piece with foreign matter may be preferably 1 mm to 50 mm, more preferably 2 mm to 10 mm, in plan view, or in plan view when the interlayer film piece is curved and stretched flat. By having a maximum length in the above range, the subsequent swelling step (S20) and / or dissolving step (S30) can be carried out more quickly, and the time and cost in the crushing step (S10) can be reduced.

[0029] <Swelling step (S20)> In the swelling step (S20), the interlayer film pieces with foreign matter obtained in the crushing step (S10) are swelled with a swelling solvent. The swelling solvent penetrates into the interlayer film pieces with foreign matter, increasing the volume of the interlayer film pieces. Therefore, in the subsequent dissolving step (S30), polyvinyl butyral contained in the interlayer film pieces is easily diffused into the dissolving solvent. In addition, the swelling also promotes the diffusion of components other than polyvinyl butyral (plasticizer, etc.) contained in the interlayer film pieces into the dissolving solvent, making it easier for the entire interlayer film pieces to dissolve in the dissolving solvent. In this way, by performing the swelling step (S20) before the dissolving step (S30), the dissolution rate of polyvinyl butyral in the dissolving step (S30) can be significantly increased, and the time required for the method of separating the foreign matter from the interlayer film with foreign matter can be significantly reduced compared to the conventional method. The volume of the interlayer film pieces with foreign matter after swelling is about 1.5 to 3 times the volume of the interlayer film pieces with foreign matter before swelling.

[0030] The swelling solvent is not particularly limited as long as it can swell the interlayer film pieces containing polyvinyl butyral. 3 ) 1 / 2 More than 9(cal / cm 3 ) 1 / 2 The following solvents are preferred. The swelling solvent preferably contains one or more of carboxylate esters and aromatic hydrocarbons. Examples of carboxylate esters include acetate esters such as butyl acetate, ethyl acetate, propyl acetate, and amyl acetate, and examples of aromatic hydrocarbons include monocyclic aromatic hydrocarbons having 1 to 3 substituents substituted with methyl groups, such as toluene, xylene, and trimethylbenzene. Of these solvents, it is preferred to use butyl acetate, since it allows good swelling of polyvinyl butyral and is highly safe.

[0031] The amount of swelling solvent used in the swelling step (S20) may be preferably 150 parts by mass or more and 2000 parts by mass or less, more preferably 400 parts by mass or more and 1100 parts by mass or less, relative to 100 parts by mass of the interlayer film pieces with foreign matter to be treated. By using an amount of swelling solvent of 150 parts by mass or more, a sufficient swelling effect can be obtained, and by using an amount of swelling solvent of 2000 parts by mass or less, the use of an excessive amount of solvent can be avoided, thereby reducing costs.

[0032] The swelling step (S20) is preferably carried out while heating. Heating increases the rate at which the swelling solvent penetrates into the interlayer film pieces, allowing for more rapid swelling. When heating, the interlayer film pieces with foreign matter or the swelling solvent, or both, are heated. The heating means is not particularly limited. For example, a container containing the interlayer film pieces with foreign matter and the swelling solvent is heated by a heater. The swelling step (S20) can further use a stirrer, a vibrator, or a condenser for refluxing the solvent.

[0033] The heating temperature may be any temperature below the boiling point of the swelling solvent, and is preferably 40° C. to 80° C., and more preferably 50° C. to 70° C. By setting the heating temperature at 50° C. or higher, the penetration speed of the swelling solvent into the intermediate film pieces can be further increased, and the swelling step (S20) can be carried out quickly. In addition, by setting the heating temperature at 70° C. or lower, the volatilization of the swelling solvent can be suppressed, and safety can be ensured.

[0034] In addition, the swelling step (S20) is preferably performed while moving the contents of the container, i.e., the swelling solvent and / or the interlayer film pieces with foreign matter. Specifically, a means for placing inside the container, such as a stirring means, such as a stirring blade, a magnetic stirrer, or a stirring ball, may be used, or a means for applying vibration to the container from the outside, such as an ultrasonic generating means or a shaking means, may be used. Among these, it is preferable to use a stirring means, since it can smoothly flow the swelling solvent and is easy to handle.

[0035] Prior to the swelling step (S20), the resin contained in the intermediate film piece, specifically polyvinyl butyral, may be subjected to a pretreatment such as chemical modification.

[0036] <Dissolution process (S30)> In the dissolving step (S30), the intermediate film pieces swollen in the swelling step (S20) are dissolved in a dissolving solvent. By dissolving the intermediate film pieces, even if foreign matter is embedded in the intermediate film pieces, it is possible to separate the foreign matter from the intermediate film pieces.

[0037] The dissolving solvent is not particularly limited as long as it can dissolve polyvinyl butyral. It is preferable that the dissolving solvent is a solvent that can also dissolve resin components other than polyvinyl butyral contained in the intermediate film pieces, such as plasticizers. The solubility parameter of the dissolving solvent is 9 (cal / cm 3 ) 1 / 2 More than 15(cal / cm 3 ) 1 / 2The dissolution solvent may be lower alcohols having 4 or less carbon atoms, as well as chloroform, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, etc. Specific examples of lower alcohols include methanol, ethanol, propanol (including n-propyl alcohol and isopropyl alcohol (IPA)), and butanol. Of these, it is preferable that the dissolution solvent contains ethanol, since it can dissolve polyvinyl butyral well. Furthermore, it is preferable to use denatured alcohol containing ethanol and isopropyl alcohol as the dissolution solvent, since it is inexpensive and easy to handle.

[0038] The amount of the dissolving solvent used in the dissolving step (S30) may be preferably 150 parts by mass or more and 2000 parts by mass or less, more preferably 400 parts by mass or more and 1100 parts by mass or less, relative to 100 parts by mass of the interlayer film pieces with foreign matter to be treated. By setting the amount of the dissolving solvent to 150 parts by mass or more, the interlayer film pieces to be treated can be sufficiently dissolved, and by setting the amount to 2000 parts by mass or less, the use of an excessive amount of solvent can be avoided, thereby reducing costs.

[0039] The ratio (w3 / w2) of the mass (w3) of the dissolving solvent used in the dissolving step (S30) to the mass (w2) of the swelling solvent used in the swelling step (S20) may be preferably 0.5 to 2, more preferably 0.75 to 1.25. By setting the ratio within the above range, necessary and sufficient swelling can be achieved, increasing the dissolution rate, and preventing either the swelling solvent or the dissolving solvent from becoming excessively large and being wasted.

[0040] The dissolving step (S30) is also preferably performed with heating, as in the swelling step (S20). Heating activates the components contained in the intermediate film pieces, increasing the dissolution rate of the intermediate film pieces and enabling more rapid dissolution. When heating, the intermediate film pieces with foreign matter or the dissolving solvent, or both, are heated. In addition, the heating means in the dissolving step (S30) can be the same as the heating means used in the swelling step (S20).

[0041] When heating is performed in the dissolving step (S30), the heating temperature may be equal to or lower than the boiling point of the dissolving solvent, and is preferably 40° C. to 80° C., and more preferably 50° C. to 70° C. By setting the heating temperature at 50° C. or higher, the dissolution rate of the intermediate film pieces in the dissolving solvent can be further increased, and the dissolving step (S30) can be performed quickly. In addition, by setting the heating temperature at 70° C. or lower, the volatilization of the dissolving solvent can be suppressed, and safety can be ensured.

[0042] In the dissolving step (S30), similarly to the swelling step (S20), it is preferable to move the contents of the container, i.e., the dissolving solvent and / or the intermediate film pieces with foreign matter. In the dissolving step (S30), the means for moving the dissolving solvent and / or the intermediate film pieces with foreign matter can be the same as the means used in the swelling step (S20).

[0043] The ratio of the mass of the intermediate film pieces to the sum of the mass of the intermediate film pieces obtained by subtracting the mass of the foreign matter from the mass of the intermediate film pieces with foreign matter and the mass of the total solvent added until the end of the dissolving step (S30) may be preferably 2.5% by mass or more and 25% by mass or less, more preferably 3.5% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less. The mass of the total solvent added until the end of the dissolving step (S30) may be the sum of the mass of the swelling solvent and the mass of the dissolving solvent. By making the ratio of the mass of the intermediate film pieces 2.5% by mass or more, it is possible to prevent the solvent from becoming excessive and to increase the efficiency of the treatment. In addition, by making it 25% by mass or less, it is possible to avoid the interference with the operation such as stirring for increasing the swelling rate and / or dissolving rate in the swelling step (S20) and / or dissolving step (S30). In the method according to the present embodiment, in addition to the swelling solvent and dissolving solvent, other solvents may be added to the extent that they do not affect the swelling step (S20) and the dissolving step (S30). In that case, the other solvents are also included in the above "total solvents."

[0044] At the time when the dissolving step (S30) is completed, the liquid portion of the contents of the container, i.e., the concentration of polyvinyl butyral in the solution containing polyvinyl butyral, can be preferably 2.5% by mass or more and 25% by mass or less, more preferably 3.5% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less. By making the concentration 5% by mass or more, it is possible to prevent the solvent from becoming excessive and to increase the efficiency of the treatment. In addition, by making the concentration 10% by mass or less, it is possible to avoid the interference with the operation such as stirring for increasing the swelling rate and / or dissolution rate in the swelling step (S20) and / or dissolving step (S30).

[0045] The viscosity of the solution containing the polyvinyl butyral was 2.4 s -1 It is preferable that the viscosity is 30 mPa s or more and 3000 mPa s or less under the above conditions. By setting the viscosity within the above range, the efficiency of the treatment can be increased, and it is also possible to avoid interference with operations such as stirring for increasing the swelling rate and / or dissolution rate.

[0046] <Separation process (S40)> By the dissolving step (S30), the polyvinyl butyral contained in the interlayer film piece with foreign matter is dissolved in the dissolving solvent, and preferably the interlayer film portion of the interlayer film piece with foreign matter is dissolved in the dissolving solvent. In the separation step (S40), the foreign matter is separated into a solid component that is not dissolved in the dissolving solvent and a solution containing polyvinyl butyral. In addition to polyvinyl butyral, the solution may contain components that are soluble in the dissolving solvent. The components that are soluble in the dissolving solvent may be, for example, components such as plasticizers contained in the interlayer film, or components that constitute the liquid crystal contained in the liquid crystal cell when the foreign matter originates from the liquid crystal cell.

[0047] The separation method used in the separation step (S40) is not particularly limited. In the separation step (S40), filtration, decantation, etc. can be used, but since foreign matter can be efficiently separated, it is preferable to perform the above separation by filtration. When filtration is used, in addition to gravity filtration at normal pressure, reduced pressure filtration (vacuum filtration), pressure filtration, etc. may be used. Also, a filter bag can be used for filtration, and in that case, it is preferable to use one with a filtration accuracy of 0.5 μm to 50 μm.

[0048] As described above, the viscosity of the solution containing the polyvinyl butyral was 2.4 s -1 By controlling the viscosity within the above range, foreign matter can be separated in a short time by gravity filtration without the need for equipment specifications for pressure filtration.

[0049] As shown in FIG. 2, the above-mentioned separation step (S40) can obtain foreign matter and a solution containing polyvinyl butyral (PVB solution). If the foreign matter obtained has been filtered through a filter bag in the separation step (S40), it can be scraped off and collected from the filter bag. The foreign matter obtained may be collected after being washed with water or the like. The foreign matter is treated or processed according to its type and the purpose of reuse. For example, if the foreign matter originates from a metal wire, it can be treated according to a known metal regeneration process. In that case, it can be processed again as a metal wire and used. The filter bag can be reused by washing it with the dissolving solvent used in the dissolving step (S30) immediately after the separation step (S40) to prevent clogging of the filter.

[0050] The solution containing polyvinyl butyral may be provided to a reuse destination in the form of a solution without any additional treatment. The solution containing polyvinyl butyral may also be subjected to some additional treatment. For example, the solution containing polyvinyl butyral may be heated and the evaporated solvent cooled in a condenser to recover a part of the solvent contained in the solution (S50). This results in a solution containing polyvinyl butyral at a higher concentration. This concentration can be adjusted depending on the purpose of reusing the polyvinyl butyral. The concentration of the solution containing polyvinyl butyral after concentration can be 15% by mass or more and 30% by mass or less.

[0051] The recovered polyvinyl butyral can be used as an adhesive, a binder for inks or paints, etc. It is also expected that the recovered polyvinyl butyral can be used to produce an interlayer film for laminated glass.

[0052] In the above-mentioned recovery step (S50), for example, distillation or the like can be used to recover the solvent. In that case, it is possible to recover each type of solvent. This allows, for example, the swelling solvent and the dissolving solvent to be recovered separately. The solvent recovered in the step (S50) of recovering a part of the solvent may be reused. For example, as shown in FIG. 2, the recovered swelling solvent may be returned to the swelling step (S20) and reused. Also, the recovered dissolving solvent may be returned to the dissolving step (S30) and reused. That is, the method according to the present embodiment may further include recovering the solvent contained in the polyvinyl butyral solution as a recovered solvent, and using the recovered solvent in the above-mentioned swelling step (S20) and / or dissolving step (S30).

[0053] [Device for separating foreign matter from interlayer film with foreign matter] One embodiment of the present invention is an apparatus used in the above-mentioned method for separating foreign matter from a foreign matter-containing interlayer film. Specifically, one embodiment is an apparatus for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass having an interlayer film, and includes a swelling section that swells the foreign matter-containing interlayer film pieces obtained from the laminated glass with a swelling solvent, a dissolving section that dissolves the polyvinyl butyral contained in the foreign matter-containing interlayer film pieces with a dissolving solvent, and a separation section that separates the foreign matter from a solution containing the polyvinyl butyral.

[0054] The parts of the inner wall of the device that come into contact with the solvent are made of a material that is not likely to swell, dissolve, or corrode due to the solvent under the conditions of the treatment temperature, time, etc. Specifically, metal, glass, polyethylene, or polypropylene are used. Metal lined with glass, polyethylene, or polypropylene may also be used. The dissolving solvent used in the dissolving step is used to wash the above contact parts. The washing liquid can be reused in the dissolving step, or can be used to adjust the concentration of the polyvinyl butyral solution after separation in the separation section. EXAMPLES

[0055] Hereinafter, the embodiment of the present invention will be further described based on experimental examples.

[0056] (Example 1) =Pre-process= The laminated glass used was an automobile window glass with a tungsten wire, which is a thermoelectric wire, embedded therein. The automobile window glass was made by sandwiching an interlayer film containing polyvinyl butyral as a main component between two glass sheets, and the tungsten wire was disposed between the glass sheet facing the inside of the vehicle and the interlayer film. The automobile window glass was crushed by being sandwiched between two bladed rolls, and was further rocked in an aqueous surfactant solution to separate the glass cullet remaining on the surface of the interlayer film, thereby obtaining an interlayer film with foreign matter (an interlayer film with a tungsten wire).

[0057] =Crushing process= The interlayer film with foreign matter obtained as described above was shredded using a cross-cut shredder (Micro-Cut Shredder PSD039, manufactured by Sanwa Supply Co., Ltd.) to obtain interlayer film pieces with foreign matter that were rectangular in plan view when stretched out flat and had an average size of 5 mm x 20 mm.

[0058] =Swelling process= 90 g of the resulting interlayer film pieces with foreign matter attached were placed in a 5 L glass container, and 900 g of butyl acetate, a swelling solvent, was added. The contents, with the interlayer film pieces with foreign matter attached immersed in butyl acetate, were stirred for 1 hour with a mechanical stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) using four pitched paddle blades at 100 rpm while maintaining the liquid temperature at 50°C. One hour after the start of stirring, swelling of the interlayer film pieces with foreign matter was visually confirmed.

[0059] =Dissolution process= Next, 800 g of denatured alcohol (Mixed Ethanol NP manufactured by Yamaichi Chemical Industry Co., Ltd., ethanol 85.5%, isopropyl alcohol 9.6%, methanol 4.9%) was added as a dissolution solvent, and the mixture was stirred at 200 rpm with four pitched paddle blades using the mechanical stirrer described above, while maintaining the liquid temperature at 50 ° C. One hour after the start of the dissolution process, it was visually confirmed that the intermediate film pieces were almost completely dissolved in the dissolution solvent. A tungsten wire was visually observed at the bottom of the container. The ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces obtained by subtracting the mass of the foreign matter from the mass of the intermediate film pieces with foreign matter and the mass of all the solvent added by the end of the dissolution process (the ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces, swelling solvent, and dissolution solvent) was 5.0 mass%.

[0060] =Separation process= The contents of the container were transferred to a filter bag (polypropylene nonwoven fabric manufactured by 3M, nominal filtration accuracy 10 μm), and the tungsten wire was filtered out of the polyvinyl butyral-containing solution under normal pressure due to the weight of the liquid (gravity filtration). The time required for filtration was 2 minutes. As a result, approximately 0.5 g of tungsten wire was recovered. The mass of the polyvinyl butyral-containing solution that passed through the filter bag was 1600 g. The concentration of polyvinyl butyral in the polyvinyl butyral-containing solution was 5 mass%. The viscosity of the polyvinyl butyral-containing solution was 1.0 g at a shear rate of 2.4 s -1 The viscosity was 35 mPa·s under the above conditions.

[0061] (Example 2) The experiment was carried out in the same manner as in Example 1, except that the mass of the interlayer film piece with foreign matter (interlayer film piece with tungsten wire) was 185 g. In the dissolution process, it was visually confirmed that the interlayer film piece was almost completely dissolved in the dissolution solvent 3 hours after the start of the process. In the separation process, the time required for filtration was 15 minutes. The mass of the recovered tungsten wire was about 1 g. The mass of the polyvinyl butyral-containing solution that passed through the filter bag was 1600 g.

[0062] The ratio of the mass of the intermediate film pieces to the sum of the mass of the intermediate film pieces obtained by subtracting the mass of the foreign matter from the mass of the intermediate film pieces with foreign matter and the mass of all the solvent added until the end of the dissolution process (the ratio of the mass of the intermediate film pieces to the sum of the mass of the intermediate film pieces, swelling solvent, and dissolution solvent) was 10 mass%. In addition, the concentration of polyvinyl butyral in the polyvinyl butyral-containing solution separated in the separation process was 10 mass%. In addition, the viscosity of the polyvinyl butyral-containing solution was 10% by mass at a shear rate of 2.4 s -1 The viscosity was 2600 mPa·s under the above conditions.

[0063] (Example 3) The experiment was carried out in the same manner as in Example 1, except that an antenna was embedded in the laminated glass instead of a tungsten wire. In the laminated glass used, a polyethylene terephthalate (PET) film with a metal (copper line) pattern constituting the antenna was placed between the glass sheet on the inside of the vehicle and the interlayer. In the dissolution process, it was visually confirmed that the interlayer piece was almost completely dissolved in the dissolution solvent two hours after the start of the process. The mass of the PET film with the metal pattern collected was about 1 g. The mass of the polyvinyl butyral-containing solution that passed through the filter bag was 1500 g.

[0064] The ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces obtained by subtracting the mass of the foreign matter from the mass of the intermediate film pieces with foreign matter and the mass of all the solvents added until the end of the dissolving process (the ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces, swelling solvent, and dissolving solvent) was 4.5 mass%. In addition, the concentration of polyvinyl butyral in the polyvinyl butyral-containing solution separated in the separation process was 4.5 mass%.

[0065] (Example 4) The experiment was carried out in the same manner as in Example 1, except that a laminated glass in which a liquid crystal cell was enclosed, instead of a tungsten wire, was used as the laminated glass. In the laminated glass used, a liquid crystal cell containing a liquid crystal portion and a PET film with a metal pattern was disposed between the glass sheet on the inside of the vehicle and the interlayer. In the dissolution process, it was visually confirmed that the interlayer film pieces were almost completely dissolved in the dissolution solvent 3 hours after the start of the process. In addition, the mass of the recovered PET film with the metal pattern was about 30 g. The mass of the polyvinyl butyral-containing solution that passed through the filter bag was 1500 g. The liquid crystal portion of the liquid crystal cell was dissolved in the dissolution solvent in the dissolution process.

[0066] The ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces obtained by subtracting the mass of the foreign matter from the mass of the intermediate film pieces with foreign matter and the mass of all the solvents added until the end of the dissolving process (the ratio of the mass of the intermediate film pieces to the total mass of the intermediate film pieces, swelling solvent, and dissolving solvent) was 4.0 mass%. In addition, the concentration of polyvinyl butyral in the polyvinyl butyral-containing solution separated in the separation process was 4.0 mass%.

[0067] According to the above examples, it was found that the foreign matter, such as a tungsten wire or a PET film, and the polyvinyl butyral contained in the interlayer film can be separated and recovered in a short period of time from the interlayer film to which the foreign matter is attached. [Explanation of symbols]

[0068] 1. Laminated glass 11, 12 Glass plate 20 Interlayer 30 heating wire 40 Busbar 50 shielding layer

Claims

1. A method for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass having an interlayer film, comprising the steps of: a swelling step of swelling the interlayer film piece having the foreign matter obtained from the laminated glass with a swelling solvent; A dissolving step of dissolving the polyvinyl butyral contained in the interlayer film piece with foreign matter in a dissolving solvent; and a separation step of separating the foreign matter from the solution containing the polyvinyl butyral.

2. The method of claim 1 , wherein the swelling solvent comprises one or more of a carboxylic acid ester and an aromatic hydrocarbon.

3. The method of claim 1 or 2, wherein the dissolution solvent comprises a lower alcohol.

4. The method according to claim 1 or 2, wherein the ratio of the mass of the intermediate film piece to the sum of the mass of the intermediate film piece obtained by subtracting the mass of the foreign matter from the mass of the intermediate film piece with foreign matter and the mass of the total solvent added until the end of the dissolution process is 2.5 mass% or more and 25 mass% or less.

5. The viscosity of the solution containing the polyvinyl butyral is 2.4 s -1 The method according to claim 1 or 2, wherein the viscosity is 30 mPa·s or more and 3,000 mPa·s or less under the condition of

6. 3. The method according to claim 1 or 2, wherein the separating step is carried out by filtration.

7. The method further includes a crushing step of crushing the interlayer film having foreign matter obtained by separating the interlayer film from the laminated glass, thereby obtaining the interlayer film pieces having foreign matter, The method according to claim 1 or 2, wherein in the crushing step, the interlayer film with foreign matter is shredded along cutting lines in two intersecting directions.

8. Recovering the solvent contained in the polyvinyl butyral solution as a recovered solvent; 3. The method of claim 1 or 2, further comprising utilizing the recovery solvent in the swelling step and / or the dissolving step.

9. The laminated glass is a tungsten wire laminated glass for automobiles, The method of claim 1 or 2, wherein the foreign object is a tungsten wire.

10. An apparatus for separating foreign matter from a foreign matter-containing interlayer film obtained from a laminated glass having an interlayer film, comprising: a swelling section for swelling the interlayer film piece having the foreign matter obtained from the laminated glass with a swelling solvent; A dissolving section that dissolves the polyvinyl butyral contained in the interlayer film piece with foreign matter using a dissolving solvent; a separation section that separates the foreign matter from the solution containing the polyvinyl butyral.

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