JP6334247B2 - Recycled filler-containing plastic sheet and method for producing the same - Google Patents

Description

  The present invention relates to a recycled filler-containing plastic sheet and a method for producing the same.

  For the purpose of improving functionality, mixing of fillers made of particulate or powdery inorganic substances into plastics is gradually spreading. By increasing the content of the filler, the function of the film can be expanded, while the content of the material derived from petroleum raw materials can be reduced, and the cost can be reduced at the same time as reducing the burden on the environment.

  In general, waste plastics used for recycling are washed and pulverized after collection, and used as flaky raw materials. The obtained flaky waste plastic is melted by a molding machine such as an extruder, and formed into a desired shape, for example, a fiber, a sheet or the like, so that resources can be reused. However, due to the thermal history and mechanical load during melt molding, it is oxidized or hydrolyzed, resulting in molecular cutting, resulting in a lower molecular weight of the plastic, etc. In many cases, mechanical properties cannot be obtained. For this reason, the use of recycled products is limited, which has been one of the factors hindering the recycling of waste plastics.

  Therefore, it has been studied to blend with a new (virgin) resin without adding recycled pulverized flakes obtained from waste plastic (Patent Document 1) or adding a modifier (Patent Document). 2). In order to restore the properties of waste plastic with virgin resin, a considerable amount must be added, which is not economical. Also, there has been no modifier that can be used for any waste plastic.

  In addition, plastics containing fillers lose their physical properties as the filler content increases, so it is necessary to add a particularly high amount of virgin resin during recycling, resulting in offsetting the cost reduction of recycled products. It was.

JP-A-10-204207 Japanese Patent Laid-Open No. 05-092430

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a recycled filler-containing plastic sheet in which physical properties such as strength and elongation at break (elongation rate) are improved by reusing waste plastic containing filler. And

  When the present inventors cause a change in the internal structure by applying a vertical force locally while pulling the film in the flow direction on the sheet formed of the raw material plastic including the filler-containing waste plastic, the molded product after the treatment The present inventors have found that the physical properties of the sheet can be improved and have completed the present invention.

  The method for producing a recycled filler-containing plastic sheet according to the first aspect of the present invention is a molding sheet molding step in which 1) a raw material plastic containing filler-containing waste plastic is used and molded into a sheet by kneading and extrusion, 2) In the middle of moving the molding sheet in the flow direction, a solid object is pressed against the surface of the molding sheet and bent at the contact portion to generate stress acting on the inside of the molding sheet. A bending process step for processing the sheet.

  The recycled filler-containing plastic sheet according to the second aspect of the present invention is produced by the method for producing a recycled filler-containing plastic sheet according to the first aspect.

  According to the present invention, there is provided a recycled filler-containing plastic sheet having a physical property such as sufficient strength and elongation at break (elongation rate) by reusing waste plastic having a shape such as particles, powder or fragments containing filler. Can be obtained.

It is a figure which shows typically the one aspect | mode of the solid object cross section of this invention. It is a figure which shows typically another one aspect | mode of the solid object cross section of this invention. It is a figure which shows typically the one aspect | mode of the manufacturing method of the plastics of this invention.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. .

  The method for producing a recycled filler-containing plastic sheet according to the present invention is as follows: 1) Using raw material plastic containing filler-containing waste plastic, and molding into a sheet by kneading and extrusion; 2) Flowing the molded sheet In the middle of moving in the direction, the solid object is pressed against the surface of the molded sheet and bent at the contact portion to generate a stress acting on the molded sheet to process the molded sheet. A processing step.

  The filler-containing waste plastic contains at least a thermoplastic resin and a filler. The filler-containing waste plastic can be used without particular limitation as long as it contains a particulate or powdery filler. For example, plastic molded articles used for plastic film, synthetic paper scraps, housings for home appliances and OA equipment, back covers, base grills, evaporating dishes, partition plates, cases, box covers, wall materials and floors Building materials such as wood, plastic bottles and plastic cans can be used as raw materials for raw plastics.

  As said filler containing waste plastic, what contains 40 mass% or more and 85 mass% or less of filler with respect to the total mass of the waste plastic collect | recovered can be said to be a particularly suitable material. If the filler is contained in an amount of 40% by mass or more, it is preferable because the amount of filler that is newly required during the production of the recycled filler-containing plastic sheet can be reduced. On the other hand, if the filler is contained at 85% by mass or less, it is preferable because the amount of virgin resin newly required at the time of producing the recycled filler-containing plastic sheet can be reduced.

  In addition, it is more advantageous to reduce the color material such as pigment in the filler-containing waste plastic because there is no need for a decoloring process at the time of regeneration, or the influence of the color material can be suppressed. Increased flexibility of application range. The content of the coloring material is more preferably 10% by mass or less, and preferably 5% by mass or less, based on the total mass of the filler-containing waste plastic. If it is 10 mass% or less, decoloring can be performed relatively easily.

  The plastic contained in the filler-containing waste plastic is, for example, at least one selected from the group consisting of olefin resins such as polyethylene and polypropylene, styrene resins, polyamides such as nylon 66, and polyesters such as polyethylene terephthalate. Is preferred. In particular, a crystalline plastic is preferable, and an olefin resin is particularly preferable.

  There is no problem as long as the filler is an inorganic substance powder that is conventionally added as a filler to plastic products, such as calcium carbonate, titanium oxide, silica, clay, talc, kaolin, aluminum hydroxide, or resin particle powder that is incompatible with plastic. . Moreover, in order to improve the dispersibility in the plastic sheet, the surface of these fillers may be modified in advance according to a conventional method.

  The collected filler-containing waste plastic is crushed using a known crusher after washing and removing foreign substances, and the crushed pieces may be used as raw plastic as they are, or either melted or dissolved You may pelletize by performing a well-known process. In that case, you may provide the decoloring process of a filler containing waste plastic as needed. In addition, in the above pelletization, filler-containing waste plastics, such as virgin resin, new filler, lubricant, antioxidant, ultraviolet absorber, coloring pigment, dispersant, compatibilizer, antistatic agent, flame retardant, etc. One or more components selected from various additives can also be added.

  Next, the pelletized raw material plastic is used to form a sheet by kneading and extrusion. The molded sheet of the present invention can be produced by using a conventionally known means such as a calendar method, an extrusion method, an inflation method and the like that are conventionally used. For example, the pelletized raw plastic, or the pelletized raw plastic and other components such as virgin resin are directly charged into an extruder equipped with a biaxial screw and kneaded and molded into a sheet. Further, the material is put into an extrusion molding machine equipped with a biaxial screw and kneaded to once produce an intermediate such as a pellet, and then the intermediate is further fed into a molding machine or the like to form a sheet. It can also be manufactured.

  During the kneading, together with the filler-containing waste plastic pellets, virgin resin, new filler, lubricant, antioxidant, UV absorber, coloring pigment, dispersant, compatibilizer, antistatic agent, flame retardant, etc. One or more components selected from various additives may be added.

  As the virgin resin added to the molding step of the present invention, for example, one or more kinds of resins selected from the group consisting of polyethylene, polypropylene, polystyrene, and polyethylene terephthalate can be used. As the virgin resin, it is particularly preferable to use the same type of plastic as the filler-containing waste plastic matrix in terms of compatibility, but it may be different. When a plastic different from the filler-containing waste plastic matrix is used as the virgin resin, it is preferable to use an appropriate compatibilizing agent.

  Although there is no restriction | limiting in particular in the addition amount of the virgin resin added in a shaping | molding process, It is preferable to add at 80 mass% or less with respect to the molding sheet total mass finally obtained, and 50 mass% or less is more preferable, 30 mass% or less is desirable. If the addition amount of the virgin resin is 80% by mass or less, the mechanical properties of the molded sheet can be improved. The amount of the virgin resin added is preferably as low as possible from the viewpoint of cost, but from the viewpoint of the mechanical properties of the molded sheet, it is preferably higher than 0% by mass, and more preferably 10% by mass or more. preferable.

  The filler added to the molding process of the present invention is particularly limited to inorganic substance powders conventionally added as fillers to plastic products such as calcium carbonate, titanium oxide, silica, clay, talc, kaolin, and aluminum hydroxide. Can be used without It is possible to use resin particle powder that is incompatible with plastic as a filler, but in this case, in order to improve dispersibility in the plastic sheet, the surface of these fillers should be modified in advance according to a conventional method. Is preferred.

  The addition amount of the filler added in the molding step varies depending on the filler content contained in the filler-containing waste plastic to be used and the amount of virgin resin to be added, and is not particularly limited. It is preferable to determine the content of the filler to be added so that the total filler content is 50% by mass or more and 85% by mass or less with respect to the total mass of the molded sheet.

  The content of all fillers in the molded sheet is preferably 50% by mass or more, and more preferably 60% by mass or more with respect to the total mass of the molded sheet. Moreover, it is preferable that content of all the fillers is 85 mass% or less, and 75 mass% or less is further more preferable. If the content of all the fillers is 50% by mass or more, the sheet can be stretched to increase its whiteness to a sufficient level as a processed paper. The strength and elongation rate of the molded sheet are sufficient.

  In order to adjust the surface roughness of the recycled filler-containing plastic sheet to an appropriate range and prevent large filler particles from detaching from the surface of the plastic sheet, coarse particles having a particle diameter of 50 μm or more are included in the particle size distribution range. It is preferable not to contain. On the other hand, if the filler particles are too fine, the viscosity increases remarkably when kneaded with plastic, making it difficult to produce a molded sheet. Therefore, the average particle diameter of the filler is preferably 0.5 μm or more. In addition, the particle diameter of the filler in this invention is a 50% particle diameter (d50) obtained from the distribution curve of integral% measured with the laser diffraction type particle size distribution measuring apparatus.

  In addition to the virgin resin and filler described above, the molded sheet of the present invention is selected from a lubricant, an antioxidant, an ultraviolet absorber, a coloring pigment, a dispersant, a compatibilizer, an antistatic agent, a flame retardant, and the like. One or more adjuvants can be added within a range not detrimental to the purpose. In the following, examples that are considered to be particularly important among these will be described by way of examples, but the present invention is not limited thereto.

  Examples of lubricants include stearic acid, hydroxystearic acid, complex stearic acid, oleic acid and other fatty acid lubricants, fatty alcohol lubricants, stearamide, oxystearamide, oleylamide, erucylamide, ricinolamide, behenamide, methylol Amide, methylene bisstearoamide, methylene bisstearobehenamide, bisamidic acid of higher fatty acid, aliphatic amide type lubricant such as complex amide, stearic acid-n-butyl, methyl hydroxystearate, polyhydric alcohol fatty acid ester, Examples thereof include aliphatic ester lubricants such as saturated fatty acid esters and ester waxes, and fatty acid metal soap group lubricants. These can be used alone or in combination of two or more.

  As the antioxidant, phosphorus antioxidants, phenol antioxidants, and pentaerythritol antioxidants can be used. Phosphorus antioxidants, such as phosphorous esters, more specifically phosphorous esters and phosphate esters, are preferably used. Examples of the phosphite include triphenyl phosphite, trisnonylphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, etc. Can be mentioned.

  Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris (nonylphenyl) phosphate, 2-ethylphenyl diphenyl phosphate, and the like. These phosphorus antioxidants may be used alone or in combination of two or more.

  Examples of phenolic antioxidants include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2- tert-Butyl-6- (3′-tert-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl acrylate, 2,6-di-tert-butyl-4- (N, N-dimethyl) Aminomethyl) phenol, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane Etc., and these can be used alone or in combination of two or more.

  The compatibilizing agent is not particularly limited as long as it is different depending on the combination of the filler-containing waste plastic pellets used and the virgin resin. For example, ethylene-propylene elastomer (EPR), ethylene-propylene-butadiene elastomer (EPDM), ethylene propylene rubber and ethylene propylene terpolymer, SEBC (styrene-ethylene-butadiene-olefin crystal block copolymer), SEBS (styrene-ethylene) -Known copolymers such as butadiene-styrene copolymer).

  The molded sheet of the present invention is adjusted by adding a virgin resin and / or filler to the pelletized raw material plastic, and finally the plastic and filler have a weight ratio in the range of 50:50 to 15:85. It is preferable to mix and mold so that By making the plastic and filler in the above weight ratio range, the whiteness and opacity of the sheet after extrusion can be increased, and it can be used not only in the paper field, but also by utilizing its special properties, a new material Can be processed. In addition, if stretchability is imparted to this plastic sheet, the amount of voids generated around the filler can be set to an appropriate range relatively easily when stretched, so that finally contains recycled filler. It becomes possible to adjust the apparent specific gravity, whiteness, opacity, etc. of the plastic sheet to a desired range.

  In view of productivity, mechanical properties of the obtained molded sheet, ease of control of film thickness, applicability to various resins, environmental load, etc. Is preferred. Among these, in order to arbitrarily adjust the apparent specific gravity and the like by changing the sheet structure, it is preferable to first form a molded sheet by extrusion molding using a T-die method.

  Production of the molded sheet is a method in which the above-described constituent materials are put into a kneading extrusion molding machine in which a T die is set at a predetermined blending ratio, and the constituent materials are melt-kneaded and then directly formed into a film in the same machine. Applicable. Also, once the constituent materials are put into a kneading extruder at a predetermined compounding ratio, melted and kneaded to form pellets, the resulting pellets (compounds) are further put into another extruder with a T-die set, and a film It can also be converted. If the extruder to be used is a twin screw extruder, it is particularly preferable because these components can be uniformly melted and dispersed by the action of the strong shearing force to easily obtain a highly filled sheet. When there is no problem in the dispersibility of the components to be combined, the sheet may be formed with a single screw extruder.

  The average thickness of the molded sheet of the present invention can be arbitrarily selected depending on the application and taking into account the stretch ratio after forming into a sheet. Considering the final thickness of the plastic sheet obtained from the molded sheet, the average thickness of the molded sheet is preferably in the range of 50 μm to 400 μm, and more preferably 100 μm to 300 μm. If the average thickness of the molded sheet is greater than 50 μm, sufficient elongation at break can be ensured, so that the tolerance to stretching is improved and the physical properties of the plastic sheet can be easily adjusted to a desired range. Become. If the thickness is less than 400 μm, the final product can be adjusted to an appropriate thickness, and the load necessary for stretching does not become excessive, and the stretching process becomes easy.

  In addition, when calculating | requiring the average thickness of the sheet | seat correctly in this invention, the thickness in the position of 10 points | pieces selected arbitrarily of the sheet | seat obtained by shaping | molding is dial gauge micrometer which can apply a constant pressure. Measure and average the obtained values.

  Since the above molded sheet has a high filler content and uses waste plastic, it is hard and brittle under normal production conditions, so it is impossible or extremely difficult to apply processing such as stretching. The degree is extremely small.

  The present inventor unexpectedly imparts sufficient flexibility to the molded sheet by adding a bending process described below to the molded sheet, although waste plastic is used as a raw material. As a result, it has been found that the tolerance of the subsequent stretching treatment conditions can be improved.

  In the present invention, a long solid object such as a rod, plate or beam is pressed against the surface of the molded sheet so that the longitudinal direction thereof intersects the flow direction (machine direction, MD direction) of the sheet. The step of bending the molded sheet is provided. At that time, it is preferable to apply stress by relatively moving the object and the molded sheet in a state where the molded sheet is bent and bent at a contact portion of the object with the molded sheet. .

  In this invention, it is necessary to perform a bending process at least once with respect to the surface or back surface of a molded sheet. The bending treatment can be performed on only one or both of the front surface and the back surface of the molded sheet. However, if the bending process is performed only on one side of the molded sheet, it may cause warpage of the plastic sheet, so it is necessary to pay attention to the warpage of the sheet. It is preferable to perform the bending process on both sides of the sheet.

  When performing the bending process on both the front and back surfaces of the sheet, the bending process can be performed continuously on the front surface and the back surface, or after performing the bending process on either the front surface or the back surface, It is also possible to perform a bending process on the surface. Moreover, after winding a forming sheet around a roll and producing an original fabric roll, a bending process can also be performed with respect to this original fabric roll, and manufacture and a bending process of a molded sheet can also be performed continuously.

  Since the solid object in the present invention is brought into contact with a molded sheet having various widths and pressed against the molded sheet with a constant pressing force, it is effective to employ a long member. Specifically, it can be a member having a shape such as a bar, a plate, or a beam. When using a plate member, it uses as a part for pressing the end. In order to apply a pressure without variation to each position in the width direction of the molded sheet, the length of the solid object in the longitudinal direction is sufficiently longer than the width direction (CD direction) of the molded sheet, and the flow of the molded sheet It is preferable to arrange so as to cross the direction. At that time, it is preferable that the longitudinal direction of the solid object and the flow direction of the molded sheet be perpendicular or close to each other in order to apply a pressing force without variation at each position in the width direction of the molded sheet. Although it is desirable that the angle between the longitudinal direction of the solid object and the flow direction of the molded sheet is vertical, for example, it is set within a range of ± 20 degrees, preferably ± 10 degrees, more preferably ± 5 degrees with respect to the vertical. be able to.

  The material of the solid object in the present invention is not particularly limited, and can be selected from well-known materials according to the purpose. For example, various metal materials such as SUS, FRP, and the like can be mentioned, but are not limited thereto. In order to apply a uniform stress without variation in the width direction of the molded sheet, it is preferable to select a material having high rigidity as the material of the solid object.

  The cross-sectional shape when the solid object in the present invention is viewed in the longitudinal direction can be adopted without particular limitation, such as a circle, an ellipse, a triangle, a square, and other polygons. By using triangles, squares, or other polygons, a single solid object can be bent twice or more at the same time.

  Furthermore, it is desirable that the cross-sectional shape of the contact portion between the solid object and the molded sheet has an acute corner that does not break the sheet, or an R portion with a small radius of curvature. By making the shape of the contact portion of the solid object to the molded sheet as described above, a sufficient vertical force (force applied in the thickness direction of the film) can be applied to the molded sheet. As a result, the molded sheet The workability against is improved.

  The solid object will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a polygonal solid object (1) and an enlarged view of a contact portion thereof. The corner portion of the contact portion will be further described. The corner portion indicates a convex portion of a solid object having a polygonal cross-sectional shape, and includes a vertex (4) and two sides (2) sandwiching it. The angle of the corner is an angle (3) formed by the two sides (2) constituting the corner.

  Next, the R part of the solid object will be described. The R portion of the solid object refers to a tip of a solid object (1A) having an elliptical cross-sectional shape or a contact portion of a circular solid object. When the solid object is an ellipse, the radius of curvature refers to the radius of a circle inscribed at the apex at the tip of the ellipse. Further, as shown in FIG. 2, the R portion includes a rounded contact portion of a solid object having a polygonal cross-sectional shape. In this case, the radius of curvature is the radius (5) of the circle (6) inscribed in the apex (4A) of the contact portion.

  When the solid object has corners, the angle is preferably 6 degrees or more and 120 degrees or less when the contact portion is viewed in parallel section with respect to the flow direction of the molded sheet. More preferably, it is 20 degrees or more and 90 degrees or less, desirably 45 degrees or more and 60 degrees or less. If the angle is 6 degrees or more, the molded sheet can be bent without damaging it, and if it is 120 degrees or less, a sufficient vertical force can be applied to the entire molded sheet. In order to give a larger vertical force, it is particularly preferable to set an acute angle of 90 degrees or less.

  When the solid object has an R portion, the curvature radius is preferably 50 mm or less when the abutting portion is viewed in parallel section with respect to the flow direction of the molded sheet. More preferably, it is 10 mm or less, desirably 2.0 mm or less. When the radius of curvature of the R portion is 50 mm or less, the contact pressure per unit area of the contact portion is sufficient, and a necessary vertical force can be applied to the sheet. Further, although there is no particular lower limit value for the radius of curvature, it is preferably 0.5 mm or more from the viewpoint of preventing problems such as wear due to rubbing of the sheet.

  When the bending process is performed in a state where the molded sheet is bent at the contact portion with the solid object while being pulled, the strength and elongation at break of the molded sheet highly filled with the filler can be improved.

  This mechanism is a process in which tensile stress is applied to the inside of the molded sheet. When a strong normal force is applied by the contact of a solid object, the vertical stress acts in the thickness direction of the molded sheet, and as a result, the flow direction of the sheet. It is determined that shear stress is generated in the sheet to relax the sheet internal structure.

  In the bending process of the present invention, only one solid object may be used, but two or more solid objects may be used simultaneously.

  Then, although the manufacturing method of the reproduction | regeneration filler containing plastic sheet which concerns on this invention is demonstrated more concretely using FIG. 3, this invention is not limited to this. The above materials are put into a kneading extrusion molding machine (7) equipped with a biaxial screw at a predetermined blending ratio, heated, melted and kneaded. According to the biaxial kneading extruder, a strong shearing force can be applied to the charged raw material, and each component can be uniformly dispersed. The material put into the kneading extrusion molding machine (7) and in a molten state is supplied from the T die (8) between the pressure roll (9) and the take-up roll (10) to be formed into a sheet shape. A molded sheet (11) is formed by molding. By adjusting the speed of both the pressure roll (9) and the take-up roll (10) and the gap between the rolls, the thickness of the molded sheet (11) can be arbitrarily adjusted.

  A plurality of long solid objects (12) fixed to a frame (not shown) are provided at the tip of the take-up roll (11), and the molded sheet (11) is introduced therebetween. A winding roll (13) is provided at the tip of the solid object 12, and the molded sheet (11) is taken up in the direction indicated by the arrow by the rotation of the winding roll (13). Guide rollers (14) may be provided before and after the solid object (12).

  The long solid object (12) is arranged such that its longitudinal direction crosses the flow direction of the molded sheet (11), and the moving direction of the molded sheet (11) is the molded sheet (12) of the solid object (12). It is turned at an angle such that it can be bent at the pressing part to 11). In FIG. 3, the cross-sectional shape of the solid object (12) is a square, and the direction of motion of the molded sheet (11) is changed so that it is bent at two corners of the solid object (12).

  In FIG. 3, the vertical force and shear stress applied by the solid body (12) acting on the molded sheet (11) are speed differences caused by increasing the rotation of the take-up roll (13) rather than the rotation of the take-up roll (10). Is strengthened by the tension acting on the molded sheet (11).

  The rotational speed of the take-up roll (10) and the take-up roll (13) and the ratio thereof are preferably determined in consideration of the magnitude of the stress acting on the molded sheet (11). Further, when the molded sheet taken from the die outlet of the extruder is directly subjected to the bending process, it is necessary to determine the winding roll speed in accordance with the take-up speed from the die outlet.

  The range of the difference in rotational speed between the take-up roll (10) and the take-up roll (13) is preferably 0.08 m / min or more and 2.0 m / min or less, but the history of the formed sheet to be subjected to the bending treatment (immediately after extrusion molding, It is necessary to determine the optimum rotational speed difference according to conditions such as long-term storage.

  In FIG. 3, the molded sheet that has undergone the above bending treatment step can be once wound on a roll as it is to be a roll original, or the molded sheet can be continuously introduced into a well-known stretching machine (not shown) and stretched. After that, it may be a roll.

  As described above, the description has focused on moving the molded sheet in the flow direction, but it is also possible to adopt a mode in which the molded sheet is fixed and the solid object is moved to apply tensile stress in the sheet.

  By stretching the molded sheet that has undergone the bending process in either the flow direction or the width direction, or in both directions, various properties such as apparent specific gravity, whiteness, air permeability, and water absorption of the recycled filler-containing plastic sheet can be obtained. It can be adjusted to a desired range.

  The said extending process is performed by extending | stretching at least 1 direction of the flow direction or the width direction of the shaping | molding sheet which performed the bending process process, and a uniaxially stretched and biaxially stretched film is provided. Biaxial stretching methods include sequential biaxial stretching and simultaneous biaxial stretching, both of which can be employed.

  The draw ratio of the molded sheet after the bending process is determined in consideration of the intended use of the recycled filler-containing plastic sheet and the characteristics of the plastic used. Since the molded sheet of the present invention is highly filled with a filler, the stretching ratio is preferably 1.2 times or more and 4.0 times or less, and preferably 1.5 times or more and 3.0 times or less. Further preferred.

The necessary draw ratio can also be calculated by calculation. The weight per square meter (also referred to as basis weight) W (g / m ² ) of the molded sheet before being stretched is measured, and the apparent specific gravity D and aspect ratio (longitudinal and lateral) of the product determined in the production plan are measured. Using the following formula to determine the draw ratio (X times in the vertical direction and Y times in the horizontal direction) using the ratio R of the draw ratio in the direction (R) and the target value T (cm) of the product thickness after the transverse draw, Further, it can be easily estimated by operating experience for each apparatus.
X ² = W × 10 ⁻⁴ / (D × Z × R × T)
X = RY
Where D: Apparent specific gravity of the product as defined in the production plan
R: Aspect ratio determined by production plan (ratio of stretching ratio in the longitudinal direction and the transverse direction)
W: Weight per square meter (g) of the sheet before being longitudinally stretched
X: Longitudinal stretch ratio
Y: Stretch ratio in the transverse direction
Z: Shrinkage ratio or expansion ratio of the length in the transverse direction of the sheet by longitudinal stretching

  If this stretching is performed at a temperature lower by about 30 to 40 ° C. than the melting point of the plastic used, voids can be easily formed in the recycled filler-containing plastic sheet, the apparent specific gravity can be further reduced, and it can be made closer to plain paper. It is preferable because it is possible. In particular, when a high-density polyethylene resin is used as the plastic, the stretching is preferably performed at 95 ° C. or more and 105 ° C. or less.

  The specific gravity of the recycled filler-containing plastic sheet is reduced in accordance with void formation accompanying stretching. In addition, the combination of longitudinal stretching and lateral stretching, and as the stretching ratio is increased, the generated independent voids are connected to form a continuous void in part, so various properties such as air permeability and water absorption Can be greatly changed.

  The average thickness of the recycled filler-containing plastic film after the stretching process can be set according to the purpose of use. When used for applications in the normal paper field, the thickness is preferably 30 μm or more and 350 μm or less, preferably 80 μm or more and 300 μm or less. If it is at least 30 μm or more, the mechanical properties of the recycled filler-containing plastic film are sufficient, which is preferable.

  The recycled filler-containing plastic sheet prepared by the production method of the present invention may be subjected to surface modification on both sides or one side depending on the purpose. As such surface modification, many other treatment methods are known, such as hydrophilization, hydrophobization and gas barrier properties, and a method for imparting a desired function can be appropriately selected from these methods. Is possible.

  For example, in order to make the recycled filler-containing plastic sheet hydrophilic after stretching, a method of applying an aqueous treatment agent containing an aqueous polymer as a main ingredient to the plastic sheet, or a method such as oxygen plasma treatment Is applicable. In the former case, it is preferable to crosslink the cationic group-containing aqueous polymer in the aqueous treatment agent with a specific amount of a water-soluble crosslinking agent. Aqueous polymers that can be used are polymers that are inherently water-soluble, such as polyvinyl alcohol and polyacrylic acid, or polymers that have been rendered water-soluble for the first time by introducing various cationic groups. Can do.

  The degree of hydrophilicity imparted to the surface of the recycled filler-containing plastic sheet varies depending on the processed material to be formed thereafter, but in the water contact angle measurement in JIS R3257: 1999, the contact angle is 90 degrees or less, preferably 40 degrees or more and 90 degrees. It is preferable to adjust so that it may become the following. When the water contact angle exceeds 90 degrees, it becomes difficult to form a uniform layer of the processed material.

  When surface modification for imparting various gas barrier properties is performed on the recycled filler-containing plastic film after stretching, for example, a gas barrier layer made of silicon oxide is formed on the surface of the plastic film in a vacuum. In order to develop a high gas barrier property, a plasma chemical vapor deposition (CVD) method is preferred at present, and the film can be formed on one side or both sides of the plastic film. At this time, it is preferable to perform continuous vapor deposition of a roll-shaped plastic film by a winding method. For example, a known winding-type vacuum deposition apparatus can be used. At this time, a low-temperature plasma generator such as direct current (DC) plasma, low-frequency plasma, high-frequency plasma, pulse wave plasma, tripolar plasma, or microwave plasma is used as the plasma generator.

  The gas barrier layer made of silicon oxide laminated by the plasma CVD method can be formed using a silane compound having carbon in the molecule and oxygen gas as raw materials, and can be formed by adding an inert gas to the raw materials. it can. Examples of silane compounds having carbon in the molecule include tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), tetramethylsilane (TMS), hexamethyldisiloxane (HMDSO), tetramethyldisiloxane, and methyltrimethoxysilane. A relatively low molecular weight silane compound can be selected. One or more of these silane compounds can also be used.

  In film formation by the plasma CVD method, the silane compound vaporized and mixed with oxygen gas is introduced between the electrodes, and electric power is applied by a low-temperature plasma generator to form a film. At this time, the film quality of the barrier layer can be changed by various methods such as changing the silane compound and the gas type, mixing ratio of the silane compound and oxygen gas, and increasing or decreasing the applied power.

  Furthermore, it can be set as the laminated | multilayer film which can respond to a wide use by providing a functional layer in the said recycled filler containing plastic sheet. Examples of the functional layer include, but are not limited to, an ink receiving layer, an antistatic layer, a metal layer, a printed coloring layer, and an adhesive layer. Further, a plurality of these can be selected and laminated.

  The recycled filler-containing plastic sheet obtained by the production method of the present invention can be used without particular limitation in the fields of printing paper, packaging paper, insulating paper, packaging containers, bags, labels, tapes and the like.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

<Example 1>
Using a twin-screw kneading extruder equipped with a T die (manufactured by Hitachi Zosen), the high-density polyethylene resin (PE) and calcium carbonate powder are adjusted to a mass ratio of 20:80, and magnesium stearate Was blended to 1% by mass with respect to both raw materials, directly kneaded after kneading to create a sheet filled with 80% calcium carbonate, and this sheet (thickness of about 200 μm) was stored at room temperature for 6 months or more And used as a model of waste plastic containing filler.

  The above sheet is a cutter type pulverizer (3 rotary blades, 4 fixed blades, spindle rotation speed 1,000 rpm) manufactured by Turbo Industry Co., Ltd. (currently Freund Turbo). It was cut into strips and used as raw plastic. The raw plastic strips were kneaded at a preset temperature of 240 ° C. using a small biaxial kneading extrusion molding machine (Technobel) equipped with a T-die, and extruded to produce a molded sheet.

  A rectangular solid object as shown in FIG. 3 was provided at two locations between a take-up roll and a take-up roll of a small biaxial kneading extrusion molding machine, and a part for bending treatment on the back surface and the surface was provided. Using this equipment, the rotation speed of the take-up roll (90 ° C.) is set to 0.60 m / min, and the rotation speed of the take-up roll (30 ° C.) is set to 1.36 m / min. did. Here, the angle of the used solid object corner is 90 °. The thickness of the recycled filler-containing plastic sheet prepared as described above was 0.20 mm.

<Comparative Example 1>
At the time of manufacturing a molded sheet, after the sheet is taken up from the die exit to the take-up roll (90 ° C.), it is immediately taken up by the take-up roll (30 ° C.). A recycled filler-containing plastic sheet was prepared in the same manner as in Example 1 except that it was set to / min. What is the average thickness of the resulting recycled filler-containing plastic sheet? It was 0.20 mm.

<Comparative example 2>
Using the small biaxial kneading extruder used in Example 1, the high density polyethylene resin pellets and calcium carbonate powder were adjusted to a mass ratio of 20:80, and magnesium stearate was used as both raw materials. The mixture was mixed so as to be 3% by mass, kneaded at a set temperature of 220 ° C., and extruded as it was. Bending treatment was performed on the molded sheet from the die outlet under the conditions of the take-up roll rotation speed of 0.63 m / min and the take-up roll rotation speed of 1.47 m / min with the bending treatment equipment used in Example 1. As a result, a bent sheet was obtained. The average thickness of the obtained sheet was 0.20 mm.

<Comparative Example 3>
After taking the molded sheet from the die exit to the take-up roll (90 ° C.), immediately set the rotation speed of the take-up roll and the take-up roll to 0.66 m / min when winding up on the take-up roll (30 ° C.), A sheet was obtained in the same manner as in Comparative Example 3 except that the bending treatment was not performed. The average thickness of the obtained sheet was 0.20 mm.

[Evaluation of strength and elongation of plastic sheet]
From the plastic sheet obtained above, a strip test piece having a width of 15 mm was cut out in the machine direction (MD) and the vertical direction (TD), and a tensile testing machine (manufactured by A & D Co., Ltd.) equipped with a 1000 N load cell was attached. A tensile test was performed at 25 ° C. under the conditions of a tensile speed of 500 mm / min and a distance between chucks of 100 mm, and the strength and elongation at the time of film breakage were measured. The results are shown in Table 1 as tensile strength and elongation rate, respectively.

  A sheet containing 80% calcium carbonate in Table 1 was allowed to stand at room temperature for 6 months or longer, then cut into strips having a long side of 1 to 2 mm or less, kneaded and extruded to form a recycled sheet (Comparative Example 1). Compared with a virgin sheet (Comparative Example 3) formed by kneading and extruding high density polyethylene resin (PE) pellets and calcium carbonate powder, the strength and elongation ratio were significantly reduced. On the other hand, when the bending process step of the present invention described above was performed, both the strength and the elongation rate of the sheet were remarkably improved as is apparent from Example 1 and Comparative Example 2. Moreover, the strength ratio (characteristic improvement rate) of the processed product of the recycled sheet (Example 1) to the untreated product (Comparative Example 1) is high, and the untreated product of the sheet (Comparative Example 2) obtained by bending the virgin sheet (Comparative Example 2) The strength ratio (characteristic improvement rate) with respect to Comparative Example 3) is significantly exceeded.

<Examples 2 to 4>
Without newly replenishing calcium carbonate powder, the filler-containing waste plastic model strip (recycled product) prepared in Example 1 and virgin polyethylene resin pellets were combined into a total amount of high-density polyethylene resin (PE). It mixed so that it might become 40%, 30%, and 20%, and it was set as the raw material plastics of Examples 2-4, respectively. Subsequently, using the same equipment as in Example 1, except for the kneading set temperature, the take-up roll and the rotation speed of the take-up roll, the molded sheets of Examples 2 to 4 were prepared. Table 2 shows the kneading preset temperature and the rotation speed of the roll in each example.

<Comparative Examples 4-6>
Without newly replenishing calcium carbonate powder, the filler-containing waste plastic model strips prepared in Example 1 and the virgin high-density polyethylene resin pellets had a total amount of polyethylene resin (PE) of 40%, 30 % And 20% were mixed to obtain raw material plastics of Comparative Examples 4 to 6, respectively. Subsequently, using the same equipment as in Comparative Example 1, except for the kneading set temperature, the take-up roll, and the rotation speed of the take-up roll, the molded sheets of Comparative Examples 4 to 6 were prepared. Table 2 shows the kneading preset temperature and the rotation speed of the roll of each comparative example.

<Comparative Examples 7-9>
The mass ratio of the virgin high density polyethylene resin (PE) pellets and calcium carbonate powder was changed to 40:60, 30:70, 20:80, the kneading set temperature was 220 ° C., the take-up speed and the take-up speed were 0.80 m / Molded sheets of Comparative Examples 7 to 9 were prepared in the same manner as Comparative Example 3 except that it was set to min. Table 2 shows the kneading preset temperature and roll rotation speed of each comparative example.

[Evaluation of strength and elongation of plastic sheet]
From the plastic sheet obtained above, a strip-shaped test piece having a width of 15 mm was cut out in the machine direction (MD), a tensile test was performed under the same conditions as above, and the strength at the time of film breakage was measured. Shown in

  When the bending treatment is not performed, it is inevitable that the strength of the sheet containing only the recycled material in the matrix (Comparative Example 6) is lower than that of the sheet containing only the virgin material (Comparative Example 9). This strength reduction can be improved to some extent by adding virgin polyethylene, as is apparent from comparison between Comparative Examples 4 and 5 and Comparative Examples 7 and 8. On the other hand, the molded film of Example 4 which has undergone the bending process of the present invention is not inferior to the molded sheet of Comparative Example 9 prepared by the addition of virgin polyethylene resin, even without the addition of virgin polyethylene resin. Intensity was shown. The tensile strengths of the molded sheets of Examples 2 and 3 in which both the addition of the virgin polyethylene resin and the bending treatment were performed were further improved as compared with Example 4 in which the virgin polyethylene resin was not added.

1, 1A Solid object 11 Molded sheet 12 Solid object

Claims (6)

1) Using a raw material plastic including filler-containing waste plastic, forming into a sheet by kneading and extrusion, forming a molded sheet,
2) While moving the molding sheet in the flow direction, a solid object is pressed against the surface of the molding sheet and bent at the contact portion to generate stress acting on the inside of the molding sheet. Bending process for processing molded sheets, and
3) winding process,
A method for producing a recycled filler-containing plastic sheet, which has a continuous in this order . In the bending process step, the solid object is pressed against the surface of the molded sheet that is pulled in the flow direction and tensile stress is applied to the inside thereof. The method for producing a recycled filler-containing plastic sheet according to claim 1, wherein normal stress is applied and shear stress is generated. 3. The method for producing a recycled filler-containing plastic sheet according to claim 1, wherein the contact portion of the solid object has a corner portion having an angle of 6 degrees or more and 120 degrees or less as viewed in a cross section parallel to the flow direction. 3. The method for producing a recycled filler-containing plastic sheet according to claim 1, wherein the contact portion of the solid object has an R portion having a curvature radius of 50 mm or less as viewed in a cross section parallel to the flow direction. The manufacturing method of the recycled filler containing plastic sheet of any one of Claims 1-4 which has the extending process which extends | stretches the said forming sheet which passed through the said bending process process to the flow direction or / and the perpendicular direction. The manufacturing method of the recycled filler containing plastic sheet of any one of Claims 1-5 which adds and shape | molds a virgin resin or a filler with the pellet containing the said filler containing waste plastic in the said formation process.

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