JP2020055223A - Filter device and method for producing thermoplastic resin molded article using the same - Google Patents

Abstract

To provide a filter device capable of producing a thermoplastic resin molded article in which an amount of stagnant part generated in a housing is reduced and an amount of foreign matters such as burns and gels is small.SOLUTION: A filter device has: a flow path of processed fluid; an inflow port provided at one end of the flow path; a wall surface provided at the other end of the flow path; a housing having an outflow port provided on the wall surface; and a filter element that covers the outflow port and projects toward the flow path. The wall surface has a taper part that tapers continuously or discontinuously in a direction away from the inflow port as it approaches the outflow port side, and an angle formed with a plane orthogonal to a flow path direction exceeds 10°. A ratio {B/A} of a projected area B of the taper part in the flow path direction to a projected area A of the wall surface except the outflow port in the flow path direction is 0.7 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a filter device and a method for producing a thermoplastic resin molded article using the filter device.

  When a thermoplastic resin molded article is used for decoration of automobiles and home appliances, optical applications, and building materials, the appearance and quality of the final product are impaired if minute foreign matters are mixed in the thermoplastic resin molded article.

  As a method for removing foreign matter in a thermoplastic resin molded body, for example, a method of performing filtration using a screen mesh of 200 to 600 mesh in an extrusion step of an acrylic resin is known (see Patent Document 1). However, in the method using a screen mesh, since the filtration area is small and the strength of the mesh itself is also small, the resin pressure rises when trying to make the mesh openings fine in order to increase the filtration accuracy. And continuous productivity is limited.

  As another method for removing foreign substances in a thermoplastic resin molded body, a method of filtering a molten resin using a candle-type filter as a filter device is known. The candle-type filter has the advantage that one or more filter elements can be mounted in the housing, so that the filtration area is large and the rise in resin pressure is small even when filtering a high-viscosity molten resin. On the other hand, a stagnant portion where the resin does not easily flow is generated at the corner in the housing, and the deterioration of the resin proceeds in such a stagnant portion. Therefore, it is possible to reduce foreign substances such as burns and gel-like bodies in a long-term operation. It will be difficult.

  As a method of reducing foreign matter caused by the stagnation of the resin in the housing, an angle between a center line of a cylindrical flow path connecting the filter element and the outlet and a straight line parallel to the flow direction of the fluid at the outlet. However, a filter device in which the angle is 20 ° or more and less than 75 ° has been proposed (see Patent Document 2). Further, a filter device has been proposed in which the distance between the center of the inlet and the joint between the cap member and the support member is shorter than the radius of the inlet (see Patent Document 3).

JP-A-9-263614 JP 2017-170620 A JP 2009-196233 A

  However, when the candle type filters proposed in Patent Literatures 2 and 3 are used, the resin stagnation before the filter element cannot be solved, and the thermoplastic resin molded article may still contain foreign matter.

  The present invention has been made in view of such circumstances, and a filter device capable of reducing a stagnant portion generated in a housing and manufacturing a thermoplastic resin molded body with few foreign matters such as burns and gel-like bodies. And a method for producing a thermoplastic resin article using the filter device.

  The present inventors have studied the above problem and found that when a molten thermoplastic resin discharged from an extruder is filtered by a filter element to produce a thermoplastic resin molded body, an inlet is provided at one end of a flow path. And a wall having a wall provided with an outlet at the other end, in a direction in which the wall continuously or discontinuously separates from the inlet provided at one end of the flow path as the wall approaches the outlet. And has a tapered portion at an angle of more than 10 ° with a plane perpendicular to the flow channel direction, and the projected area in the flow channel direction of a portion of the wall surface excluding the outlet. By finding that the ratio {B / A} of the projected area B of the tapered portion in the flow path direction to A is equal to or more than a specific ratio, it has been found that foreign matters in the thermoplastic resin molded article can be suppressed. Further based on This has led to the completion of the present invention repeated studies.

That is, the present invention provides the following [1] to [13].
[1] A housing having a flow path of a fluid to be treated, an inlet provided at one end of the flow path, a wall provided at the other end of the flow path, and an outlet provided at the wall. A filter element that covers the outflow port and protrudes toward the flow path, and wherein the wall surface is continuously or discontinuously inclined in a direction away from the inflow port as approaching the outflow side. And a taper part whose angle with a plane perpendicular to the flow path direction exceeds 10 °, and the taper with respect to the projected area A in the flow direction of a portion of the wall surface excluding the outlet. The ratio {B / A} of the projected area B of the portion in the flow channel direction is 0.7 or more.
[2] The filter device according to the above [1], wherein the filtration accuracy of the filter element is 1 μm or more and 50 μm or less.
[3] A method for producing a thermoplastic resin molded article by a melt extrusion method, wherein the filter device according to [1] or [2] is arranged between an extruder and a die, and is discharged from the extruder. A method for producing a thermoplastic resin molded article, comprising a step of passing a molten thermoplastic resin through the filter device.
[4] The method for producing a thermoplastic resin article according to the above [3], wherein the residence time of the thermoplastic resin in the filter device is from 50 seconds to 1,800 seconds.
[5] The method for producing a thermoplastic resin article according to the above [3] or [4], wherein the set temperature of the housing of the filter device is 230 ° C or more and 300 ° C or less.
[6] The method for producing a thermoplastic resin molded article according to any one of [3] to [5], wherein the initial pressure difference at the inflow port and the outflow port of the filter device is from 0.1 MPa to 10 MPa.
[7] The above-mentioned [3] to [6], wherein the thermoplastic resin has a melt viscosity at a temperature of 270 ° C. and a shear rate of 122 sec− ¹ of not less than 100 Pa · s and not more than 1,500 Pa · s. A method for producing a thermoplastic resin molded article.
[8] The method for producing a thermoplastic resin article according to any one of [3] to [7], wherein the thermoplastic resin contains a (meth) acrylic resin.
[9] The (meth) acrylic resin is a homopolymer of methyl methacrylate (A); a copolymer of methyl methacrylate and acrylate (C); a homopolymer of methyl methacrylate (A) and acrylic A mixture of an acid ester homopolymer (B); a mixture of methyl methacrylate homopolymer (A) and a copolymer of methyl methacrylate and acrylate (C); 8] The method for producing a thermoplastic resin article according to [8].
[10] The method for producing a thermoplastic resin article according to any one of [3] to [9], wherein the thermoplastic resin contains rubber particles.
[11] The method for producing a thermoplastic resin article according to any one of the above [3] to [10], wherein the thermoplastic resin article is a film.
[12] The method for producing a thermoplastic resin molded article according to any of [3] to [11], wherein the thermoplastic resin molded article is an optical molded article.
[13] The method for producing a thermoplastic resin molded article according to any of [3] to [11], wherein the thermoplastic resin molded article is a decorative molded article.

  ADVANTAGE OF THE INVENTION According to this invention, the stagnation part which arises in a housing is reduced, and the filter apparatus which can manufacture the thermoplastic resin molded body with few foreign substances, such as a burn or a gel-like body, and the thermoplastic resin molding using the filter apparatus A method for producing a body can be provided.

It is a sectional view of a filter device concerning a first embodiment of the present invention. FIG. 2 is a projection view of a wall surface shown in FIG. 1 from a flow channel direction. It is a projection view corresponding to Drawing 2 of a first embodiment of a filter device concerning a second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing one embodiment of a schematic cross-sectional view along the line II of FIG. 3. FIG. 5 is a schematic sectional view showing another mode of the II schematic sectional view shown in FIG. 4.

[Filter device]
The filter device of the present invention includes a flow path for the fluid to be treated, an inlet provided at one end of the flow path, a wall provided at the other end of the flow path, and an outlet provided on the wall. A housing having
A filter element that covers the outlet and protrudes toward the flow path,
The wall surface is inclined continuously or discontinuously in a direction away from the inflow port as it approaches the outflow port side, and an angle formed by a plane perpendicular to the flow path direction exceeds 10 °. Part,
The ratio {B / A} of the projected area B of the tapered portion in the flow direction to the projected area A of the portion of the wall surface excluding the outlet in the flow direction is 0.7 or more. And
Here, that the wall surface is discontinuously inclined means that the inclined portion is separated by a non-inclined portion.
The wall surface may have a corner, but is preferably a smooth surface having no corner.

  Hereinafter, a filter device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the filter device according to the first embodiment of the present invention.
The filter device 10 includes a flow path 1 for a fluid to be treated (molten resin), an inlet 2 provided at one end of the flow path 1, a wall surface 3 provided at the other end of the flow path 1, 3 includes a housing 8 (typically, a cylindrical shape such as a cylindrical shape) having an outlet 4 and a filter element 5 that covers the outlet 4 and protrudes toward the flow path 1. The wall surface 3 constituting a part of the inner surface of the housing 8 is continuously or discontinuously inclined in a direction away from the inflow port 2 as approaching the outflow port side, and with respect to the flow path direction. The tapered portion has an angle of more than 10 ° with respect to an orthogonal plane.
Note that a support member 6 that supports the filter element 5 may be provided inside the filter element 5.
Here, the flow of the molten resin in the filter device 10 is indicated by arrows. The molten resin flowing from the inlet 2 moves inside the housing 8, passes through the filter element 5, and the filtered molten resin flows out to the outlet 4.

FIG. 2 is a projection view of the wall surface shown in FIG. The wall surface 3 has an inclined portion 7 that is continuously inclined in a direction away from the inflow port 2 as approaching the outflow port 4. The inclined portion 7 includes a tapered portion having an angle of more than 10 ° with a plane orthogonal to the flow path direction (typically, the axial direction of the cylindrical housing). The shape of the inclined portion 7 is not particularly limited as long as the inclined portion 7 is continuously or discontinuously inclined toward the outlet 4 and at least a part of the inclined portion 7 is the tapered portion. (For example, as shown in FIG. 2 as an example, when the inclined portion 7 is divided into the region 7a, the region 7b, and the region 7c, the inclination of the region 7a, the inclination of the region 7b, and the inclination of the region 7c) are the same. May be present or different. Further, at an arbitrary position, one or more portions having an angle of 10 ° or less with a plane perpendicular to the flow path direction may be provided, but all of the inclined portions 7 are tapered portions. Is preferred.
The wall may include a portion that is not inclined, but preferably does not include a portion that is not inclined.

FIG. 3 is a projection view of the filter device according to the second embodiment of the present invention, corresponding to FIG. 2 of the first embodiment. Here, an example is shown in which the wall surface 13 includes a portion P that is not inclined or has an angle of 10 ° or less with a plane orthogonal to the flow path direction even if it is inclined. The filter device 20 differs from the filter device 10 according to the first embodiment in that four filter elements are provided on the wall surface 13. A cross-sectional view corresponding to FIG. 1 of the filter device according to the second embodiment is omitted.
The wall 13 has a ramp 17 around four filter elements. The shape of the inclined portion 17 is not particularly limited as long as the inclined portion 17 is continuously or discontinuously inclined toward the outlet 14 and at least a part of the inclined portion 17 is the tapered portion. (For example, when the inclined portion 17 is divided into the region 17a, the region 17b, and the region 17c as an example, the inclination of the region 17a, the inclination of the region 17b, and the inclination of the region 17c) may be the same or different. May be. Further, at an arbitrary position, one or more portions having an angle of 10 ° or less with a plane perpendicular to the flow path direction may be provided, but all the inclined portions are tapered portions. Is preferred. The wall may include a portion that is not inclined, but preferably does not include a portion that is not inclined.

FIG. 4 is a schematic cross-sectional view showing one embodiment of a schematic cross-sectional view along the line II of FIG.
In FIG. 4, a gap is provided between the inclined surface 15 a of the filter element 15 and the inclined portion 17 of the wall surface 13. In the inclined portion 17, the region 17a, the region 17b, and the region 17c shown in FIG.

FIG. 5 is a schematic sectional view showing another mode of the II schematic sectional view shown in FIG. As shown in FIG. 5A, the inclination of the region 17a of the inclined portion 17, the inclination of the region 17b, and the inclination of the region 17c may be different. Although not shown, a portion that is not inclined may be interposed between the region 17a and the region 17b and between the region 17b and the region 17c as long as the effects of the present invention are not impaired. Is preferred.
In addition, as shown in FIG. 5B, the inclined surface 15a of the filter element 15 and the inclined portion 17 of the wall surface 13 may be partially in contact with each other, and as shown in FIG. The inclined portion 17 of the wall surface 13 may be in contact with the entire surface 15a.

  The ratio {B / A} of the projected area B of the tapered portion in the flow direction to the projected area A of the portion of the wall surface excluding the outlet in the flow direction is 0.7 or more. In the wall surface of the filter device, the larger the angle between the wall surface and the plane perpendicular to the flow direction is 0 ° or more and 10 ° or less, the larger the area from the inlet to the wall without reaching the filter element. The melted resin hardly flows inside the filter element and tends to stay there. Therefore, when the ratio {B / A} is less than 0.7, a region (stagnation portion) where the molten resin tends to stay near the wall surface becomes large, and the degradation of the molten resin proceeds in the staying portion, and the thermoplastic resin molded body There is a possibility that a large amount of foreign substances such as burns and gel-like substances may be contained in the powder. From such a viewpoint, the ratio {B / A} is preferably 0.8 or more, more preferably 0.9 or more, further preferably 0.95 or more, and more preferably 1. Particularly preferred.

(housing)
It is preferable to use a cylindrical housing as the housing. Examples of the shape of the cylindrical housing include a column, a straight column such as a square column, and the like. Especially, a cylinder is preferable.

(Filter element)
It is preferable to use a cylindrical filter element.
The cylindrical filter element usually includes a filtration part for filtering the fluid from the outer peripheral surface, a hollow part through which the filtered fluid flows, a discharge part at an end for discharging the fluid from the hollow part, and a tip part of the filter element. Examples of the tubular filter element include a tube type and a candle type. Among them, a candle type filter element is preferable.
The shape of the filtering portion of the candle type filter element is not particularly limited, and a known type such as a corrugated type or a pleated type can be used. The pleats in the pleat type may extend in the radial direction of the filter element, or may be so-called spiral pleats extending obliquely to the radial direction and having a curved or arched cross-sectional shape.

  Although there is no particular limitation on the material of the filter element, stainless steel is preferred from the viewpoint of rust resistance, corrosion resistance and strength, and SUS304 and SUS316L are more preferred. SUS316L is more preferred from the viewpoint of corrosion resistance.

  Examples of the form of the filter medium of the filter element include a powder sintered body and a fiber sintered body. These may be used in combination.

  The filter device of the present invention includes one or more filter elements. There is no particular limitation on the number of filter elements, but by increasing the number, the filtration area increases and the life of the filter elements can be extended. For example, in the production of a thermoplastic resin film, a filter device having four filter elements can be suitably used.

  The filtration accuracy of the filter element is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and still more preferably 7 μm or more and 30 μm or less, from the viewpoint of the balance between productivity and foreign matter size. . By setting the filtration accuracy to 1 μm or more, there is a tendency that thermal degradation due to shear heat generation when passing the thermoplastic resin in a molten state can be suppressed. By setting the filtration accuracy to 50 μm or less, effective removal of foreign substances can be prevented. It becomes possible.

The larger the filtration area of the filter device, the longer the filtration life, but may cause deterioration due to stagnation of the molten thermoplastic resin.
In order to exhibit the performance of the filter device of the present invention more effectively, the discharge rate of the extruder described below is Q (kg / h), the total filtration area of the filter device is S (m ² ), and the diameter of the filter element is Is D _E (mm), and the length of the filter element is L _E (mm). The total filtration area can be adjusted by the diameter, length and number of each filter element.
^{50 ≦ Q / S (kg /} m 2 · h) ≦ 200 and _{5 ≦ L E / D E ≦} 10

By setting the Q / S to 50 or more, the residence time of the thermoplastic resin in the molten state is shortened, and deterioration due to the residence of the thermoplastic resin can be suppressed. On the other hand, by setting Q / S to 200 or less, deterioration of the thermoplastic resin due to shear heat generation can be suppressed. From such a viewpoint, the Q / S is more preferably 100 or more and 180 or less, and further preferably 120 or more and 160 or less.
The residence time (s) of the thermoplastic resin in the molten state can be determined by (space volume (L) of the housing) / (ejection amount of thermoplastic resin (kg / h) / 3600 / specific gravity).

Further, by setting L _E / D _E to 10 or less, it is possible to suppress the filter element from becoming too long, shorten the residence time of the thermoplastic resin in a molten state, and suppress thermal degradation. . On the other hand, when L _E / D _E is 5 or more, the filter element can be prevented from becoming too thick, and the housing can be easily designed. From this point of _view, it is more preferred L E / _{D E} is 5 to 8.

The shape of the cylindrical filter element is usually a straight column or a frustum, and examples of the straight column include a circular column and a square column. Examples of the frustum include a truncated cone and a truncated square pyramid. Especially, a cylinder is preferable.
When two or more cylindrical filter elements are provided, it is preferable that all of the cylindrical filter elements have the same shape and the same size.
There is no particular limitation on the shape of the connection between the filter element and the housing (wall surface) and the shape of the junction after the filter element flows out.

[Method for producing thermoplastic resin molded article]
INDUSTRIAL APPLICABILITY The filter device of the present invention can be suitably used for producing a thermoplastic resin molded article by a melt extrusion method using an extruder and a die.
In the method for producing a thermoplastic resin molded article of the present invention, the filter device of the present invention is disposed between an extruder and a die, and the molten thermoplastic resin discharged from the extruder is passed through the filter device. Having a process.

  The die is not particularly limited, and can be selected according to the shape of a thermoplastic resin molded body such as a pellet, a film, a sheet, and a plate. The extruder for melting the thermoplastic resin is not particularly limited, and may be a single-screw extruder or a twin-screw extruder, and may be one unit or plural units. The extruder preferably has a vent from the viewpoint of removing moisture contained in the thermoplastic resin and monomers decomposed by the thermoplastic resin and reducing foreign matters. The vented extruder is preferably operated under reduced pressure or by flowing nitrogen. Further, if necessary, a gear pump or the like may be arranged before and / or after the filter device to measure the molten resin. When the extruder has a vent, it is preferable to arrange a gear pump between the extruder and the filter device from the viewpoint of suppressing vent up and increasing productivity.

  In the case of producing a film as a thermoplastic resin molded body, an unstretched film is obtained by extruding a molten thermoplastic resin using a T-die or the like and cooling it on a cooling roll. Stretching can be performed by optionally combining stretching devices such as a transverse stretching device and a simultaneous biaxial stretching device to obtain a stretched film. Further, from the viewpoint of the surface smoothness and the thickness uniformity of the film, it is preferable that the extruded film-like molten resin is pulled and pinched between a mirror roll or a mirror belt. It is preferable that both the mirror roll and the mirror belt are made of metal. The mirror roll is preferably a combination of a metal rigid roll and a metal elastic roll from the viewpoints of surface smoothness and thickness uniformity. The linear pressure between the mirror roll or the mirror belt is preferably 10 N / mm or more, more preferably 30 N / mm or more, from the viewpoint of surface smoothness. The surface temperature of the mirror roll or the mirror belt is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, from the viewpoint of surface smoothness, haze, appearance, and the like. Further, the temperature is preferably 130 ° C. or lower, more preferably 100 ° C. or lower.

In the method for producing a thermoplastic resin molded article of the present invention, the set temperature of the housing of the filter device is preferably 230 ° C or more and 300 ° C or less, more preferably 240 ° C or more and 280 ° C or less, and 250 ° C or more. More preferably, it is 270 ° C. or lower.
By setting the set temperature of the housing of the filter device to 230 ° C. or higher, the melt viscosity can be reduced, the rise in resin pressure is suppressed, and the continuous productivity of the thermoplastic resin molded article is improved. On the other hand, by setting the set temperature of the housing of the filter device to 300 ° C. or less, the deterioration of the resin due to heat can be further suppressed.

In the method for producing a thermoplastic resin molded article of the present invention, the residence time of the thermoplastic resin (molten resin) in the filter device is preferably 50 seconds or more and 1,800 seconds or less, and 70 seconds or more and 1,200 seconds. The time is more preferably not more than 100 seconds and more preferably not more than 100 seconds and not more than 900 seconds.
By setting the residence time of the thermoplastic resin to 50 seconds or more, the unevenness of the resin temperature is reduced, and the deterioration of the resin can be further suppressed. On the other hand, by setting the residence time of the thermoplastic resin to 1,800 seconds or less, deterioration of the resin can be further suppressed.

The initial pressure difference ((differential pressure) = (pressure on the inlet side) − (pressure on the outlet side)) at the inlet and outlet of the filter device is preferably from 0.1 MPa to 10 MPa, preferably from 1 MPa to 8 MPa. More preferably, it is 3 MPa or more and 7 MPa or less.
By setting the initial differential pressure at the inflow port and the outflow port of the filter device to 0.1 MPa or more, the drift of the molten resin can be suppressed, and the deterioration of the resin can be further suppressed. On the other hand, by setting the initial pressure difference at the inflow port and the outflow port of the filter device to 10 MPa or less, the continuous productivity of the thermoplastic resin molded article is improved, and further, the foreign matters collected by the filter element pass through the filter element. And the amount of foreign substances in the thermoplastic resin molded article can be further reduced.

(Thermoplastic resin)
The method for producing a thermoplastic resin molded article of the present invention includes a step of passing a molten thermoplastic resin (molten resin) through a filter device to remove foreign substances and the like. Here, the thermoplastic resin may be composed of only one kind of thermoplastic resin, or may be a mixture containing two or more kinds of thermoplastic resins. The thermoplastic resin has a melt viscosity at a temperature of 270 ° C. and a shear rate of 122 sec ⁻¹ of preferably 100 Pa · s or more and 1,500 Pa · s or less, more preferably 300 Pa · s or more and 1,000 Pa · s or less. preferable.
Since the melt viscosity of the thermoplastic resin at a temperature of 270 ° C. and a shear rate of 122 sec ⁻¹ is 100 Pa · s or more, when the molten resin passes through the filter device, the back pressure is sufficiently large to effectively remove foreign substances. can do. On the other hand, when the melt viscosity at a temperature of 270 ° C. and a shear rate of 122 sec ⁻¹ of the thermoplastic resin is 1,500 Pa · s or less, it is possible to prevent the filter device from being damaged due to excessive pressure applied to the filter device. In addition, the continuous productivity of the thermoplastic resin molded article is improved.
The melt viscosity can be measured by a capillograph or the like, and specifically, can be measured by the method described in Examples.

The type of the thermoplastic resin is not particularly limited, and examples thereof include (meth) acrylic resins, polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1 and polynorbornene; ethylene ionomer; methacrylic acid Methyl-styrene copolymer (MS resin); polystyrene, high-impact polystyrene, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-ethylenepropylene-styrene copolymer (AES resin), acrylonitrile-acrylic elastomer-styrene copolymer (AAS resin), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS resin), and methyl methacrylate-butadiene-styrene copolymer Resins such as polyethylene (MBS resin); polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as polyamide 6, polyamide 66, polyamide 12, polyamide 46, polyamide 9T, polyamide 10T and polyamide elastomer; polycarbonate; Vinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl phenol and ethylene-vinyl alcohol copolymer; polyacetal; polyurethane; modified polyphenylene ether and polyphenylene sulfide; acrylic thermoplastic elastomer; Ethylene / propylene-styrene copolymer (SEPS), styrene-ethylene / butylene Styrene-based thermoplastic elastomers such as styrene copolymer (SEBS) and styrene-isoprene-styrene copolymer (SIS); those composed of only polymer components such as olefin-based thermoplastic elastomers; Examples include a resin composition containing one or more kinds.
In this specification, the (meth) acrylic resin refers to a methacrylic resin and / or an acrylic resin.

The method for producing a thermoplastic resin molded article of the present invention is not particularly limited as long as it is a thermoplastic resin. Among the thermoplastic resins, (meth) acrylic resins are preferably used for various applications from the viewpoint of excellent optical properties, heat resistance, moldability and the like.
Examples of the (meth) acrylic resin include, for example, a homopolymer (A) of methyl methacrylate, a copolymer (C) of methyl methacrylate and acrylate, a homopolymer (A) of methyl methacrylate, and acrylic acid Examples include a mixture of an ester homopolymer (B), a methyl methacrylate homopolymer (A), and a mixture of methyl methacrylate and an acrylate copolymer (C).
The proportion of methyl methacrylate units contained in the copolymer of methyl methacrylate and acrylate (C) is preferably from 60% by mass to 99% by mass, and more preferably from 70% by mass to 98% by mass. Is more preferable, and it is still more preferable that it is 80 to 97 mass%.

  The acrylate is not particularly limited. Examples of the acrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.

The weight average molecular weight (Mw) of the (meth) acrylic resin is preferably from 50,000 to 150,000, more preferably from 60,000 to 150,000, and more preferably from 70,000 to 120,000. More preferably, it is not more than 2,000.
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic resin is preferably 1.5 or more and 2.6 or less, and is 1.6 or more and 2.3 or less. More preferably, it is 1.7 or more and 2.2 or less. By setting the molecular weight distribution to 1.5 or more, the moldability of the thermoplastic resin is improved, which is advantageous in that the resin is prevented from staying in the filter device. Further, by setting the molecular weight distribution to 2.6 or less, the impact resistance of the obtained thermoplastic resin molded article is improved.
The weight average molecular weight (Mw) and number average molecular weight (Mn) are values calculated by analyzing with gel permeation chromatography (GPC) and converting to the molecular weight of standard polystyrene.

  As the (meth) acrylic resin, those produced by a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be used. Among them, those obtained by the bulk polymerization method or the solution polymerization method are preferably used, and those obtained by the bulk polymerization method are more preferable from the viewpoint of obtaining a thermoplastic resin molded article having less impurities.

  The content of the (meth) acrylic resin in the thermoplastic resin is preferably from 70% by mass to 95% by mass, and more preferably from 73% by mass to 90% by mass with respect to 100% by mass of the thermoplastic resin. More preferably, it is more preferably 75% by mass or more and 85% by mass or less. The content of the (meth) acrylic resin does not include rubber particles.

The method for producing a thermoplastic resin molded article of the present invention can be suitably applied particularly to the production of a thermoplastic resin molded article containing rubber particles. This is because rubber particles tend to generate foreign matters due to stagnation. A thermoplastic resin molded article containing rubber particles can be produced by using a thermoplastic resin containing rubber particles.
The rubber particles include particles containing a polymer containing a structural unit derived from an acrylate ester (hereinafter, referred to as “acrylic elastic particles”), and a polymer containing a structural unit derived from a conjugated diene. Examples include particles, particles containing a polymer containing a structural unit derived from an acrylate ester, and a structural unit derived from a conjugated diene. In addition, these polymers may have a structural unit derived from a crosslinkable monomer as needed. In particular, when a resin containing a (meth) acrylic resin is used as the thermoplastic resin, the rubber particles are preferably acrylic elastic particles.

  The rubber particles are preferably rubber particles having a multilayer structure, and a plurality of layers are laminated in a substantially concentric manner from the core of the particles toward the outer shell, and the rubber particles are graft-bonded between the layers. Is more preferred.

  Acrylic elastic particles, which are a preferred embodiment of the rubber particles, may be particles composed of a single polymer, or particles in which polymers having different elastic moduli form at least two layers. From the viewpoint of the impact resistance of the thermoplastic resin molded article, the acrylic elastic particles are a polymer having a structural unit derived from a conjugated diene and / or an acrylic elastic polymer (for example, derived from an acrylic acid acyclic alkyl ester). Core-shell particles having a multilayer structure composed of a layer containing a polymer containing a structural unit as a main component) and a layer containing another polymer, and a layer containing an acrylic elastic polymer (core Layer) and a layer containing a methacrylic polymer (outermost layer) covering the outside (core layer) or a layer containing the methacrylic polymer (core layer) and an acrylic covering the outside. Core-shell particles having a three-layer structure consisting of a layer (intermediate layer) containing an elastomeric polymer and a layer (outermost layer) containing a methacrylic polymer that further covers the outer layer More preferably, from the viewpoint of heat resistance, and more preferably a core-shell particles having a three-layer structure.

The methacrylic polymer constituting the core-shell particles is preferably a polymer containing a structural unit derived from a non-cyclic alkyl methacrylate as a main component. In the methacrylic polymer, the content of the structural unit derived from the methacrylic acid acyclic alkyl ester is preferably from 50% by mass to 100% by mass, and more preferably from 80% by mass to 100% by mass from the viewpoint of fluidity and heat resistance. It is more preferable that the content is not more than mass%.
The methacrylic acid acyclic alkyl ester is preferably methyl methacrylate from the viewpoint of fluidity and heat resistance, and the methacrylic polymer constituting the core-shell particles has a methyl methacrylate unit content of 80% by mass or more and 100% by mass or less. Most preferably, it is contained.

  The method for producing the acrylic elastic particles is not particularly limited, and the particles can be produced by a method according to a known method (for example, International Publication No. WO 2016/121868).

  The content of the rubber particles in the thermoplastic resin is preferably 5% by mass or more and 30% by mass or less, more preferably 10% by mass or more and 25% by mass or less based on 100% by mass of the thermoplastic resin. More preferably, the content is 15% by mass or more and 23% by mass or less.

The thermoplastic resin may contain additives. The type of additive is not particularly limited, and examples thereof include an ultraviolet absorber, a polymer processing aid, a light stabilizer, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a pigment, a dye, a matting agent, and a filler. , Impact aids, plasticizers and the like. One type of additive may be used, or two or more types may be used in combination at an arbitrary ratio.
The additive may be an organic compound or an inorganic compound, but is preferably an organic compound from the viewpoint of dispersibility in a thermoplastic resin.
When the additive is contained in the thermoplastic resin, the content thereof is not particularly limited, but is preferably 0.01% by mass or more and 10% by mass or less with respect to 100% by mass of the thermoplastic resin, more preferably The content is 0.1% by mass or more and 8% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less. When the content of the additive is 0.01% by mass or more, the effect of the additive can be sufficiently exhibited, and when the content is 10% by mass or less, the inherent properties of the thermoplastic resin molded article are sufficiently maintained. it can.

Since the thermoplastic resin molded product obtained by the production method of the present invention has few foreign matter defects, it is used for decoration of automobiles and home appliances; polarizer protective film, polarizing plate protective film, retardation film, brightness enhancement film, liquid crystal substrate, light It can be suitably used for optical applications such as diffusion sheets and prism sheets; and for building materials such as wall materials, window films, window frames and bathroom wall materials. That is, the thermoplastic resin molded article obtained by the present invention can be suitably used as a decorative molded article, an optical molded article, a building material molded article, or the like.
When the thermoplastic resin molded article is an optical molded article, the total light transmittance of the optical molded article is preferably 85% or more, more preferably 90% or more, and even more preferably 92% or more.
The total light transmittance of the optical molded article can be measured in accordance with JIS K7375 (2008).

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

(Weight average molecular weight (Mw), number average molecular weight (Mn))
4 mg of the resin to be measured was dissolved in 5 mL of tetrahydrofuran (THF) and filtered with a filter having a pore size of 0.1 μm to obtain a sample solution. As the GPC device, "HLC-8320" manufactured by Tosoh Corporation equipped with a differential refractive index detector (RI detector) was used. As the column, a column in which two “TSKgel Super Multipore HZM-M” manufactured by Tosoh Corporation and “Super HZ4000” were connected in series was used. Tetrahydrofuran (THF) was used as an eluent. The temperature of the column oven was set at 40 ° C., and 20 μL of the sample solution was injected into the apparatus at an eluent flow rate of 0.35 mL / min, and the chromatogram was measured. The chromatogram is a chart in which the electric signal value (intensity Y) derived from the difference in the refractive index between the sample solution and the reference solution is plotted against the retention time X.
GPC measurement was performed using 10 standard polystyrenes having a molecular weight in the range of 400 to 5,000,000, and a calibration curve showing the relationship between the retention time and the molecular weight was created. Based on this calibration curve, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the resin to be measured were determined. Note that the baseline of the chromatogram is the point where the slope of the peak on the high molecular weight side of the GPC chart changes from zero to plus when viewed from the earlier holding time, and the slope of the peak on the low molecular weight side is the one where the holding time is earlier. The line connecting the points that change from negative to zero when viewed from above. If the chromatogram shows multiple peaks, draw a line connecting the point where the slope of the peak with the highest molecular weight changes from zero to plus and the point where the slope of the peak with the lowest molecular weight changes from minus to zero. The baseline was set.

(Melt viscosity)
After the measurement target resin (pellet) was dried at 80 ° C. for 12 hours, the melt viscosity was measured using “Capillograph 1D” manufactured by Toyo Seiki Co., Ltd. at a temperature of 270 ° C. and a shear rate of 122 sec− ¹ .

(Amount of foreign matter in film)
The film obtained in each of the Examples and Comparative Examples was cut out to a size of 1 mx 1 m on a matte black cloth (manufactured by Kawashima Textile Cellcon Co., Ltd.), and the fluorescent light was reflected from the vertical surface of the film surface. The number of foreign substances detected due to the difference in surface unevenness when visually observed using light was counted, and the number of foreign substances per 1 m ² was calculated. Note that the foreign material here refers to a foreign material having a value of width × length exceeding 0.03 mm ² .

(Production Example 1: Production of thermoplastic resin)
(1) Synthesis of (meth) acrylic resin A polymerization initiator (2,2′-azobis (2-methylpropionitrile)) was added to a monomer mixture consisting of 95 parts by mass of methyl methacrylate and 5 parts by mass of methyl acrylate. 0.1 parts by mass of hydrogen abstraction ability: 1%, 1 hour half-life temperature: 83 ° C.) and 0.21 parts by mass of a chain transfer agent (n-octyl mercaptan) were added and dissolved to obtain a raw material liquid. Separately, 100 parts by mass of ion-exchanged water, 0.03 parts by mass of sodium sulfate, and 0.45 parts by mass of a suspending and dispersing agent were mixed together to obtain a mixed solution. 420 parts by mass of the mixed solution and 210 parts by mass of the raw material liquid were charged into a pressure-resistant polymerization tank, and the temperature was increased to 70 ° C. while stirring under a nitrogen atmosphere to start a polymerization reaction. After 3 hours from the start of the polymerization reaction, the temperature was raised to 90 ° C., and stirring was continued for 1 hour to obtain a liquid in which the bead copolymer was dispersed. The obtained copolymer dispersion is washed with an appropriate amount of ion-exchanged water, the beaded copolymer is taken out by a bucket type centrifugal separator, and dried with a hot-air dryer at 80 ° C. for 12 hours to obtain a weight average molecular weight (Mw). Was 110,000 and a bead-like (meth) acrylic resin having a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 2.0 was obtained.

(2) Synthesis of rubber particles (acrylic elastic particles) A reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a monomer inlet tube, and a reflux condenser was charged with 1050 parts by mass of ion-exchanged water and dioctyl sulfo-succinic acid. After 0.5 part by mass of sodium acid and 0.7 part by mass of sodium carbonate were charged and the inside of the vessel was sufficiently replaced with nitrogen gas, the internal temperature was set to 80 ° C. After 0.25 parts by mass of potassium persulfate was added thereto and the mixture was stirred for 5 minutes, a monomer composed of methyl methacrylate: methyl acrylate: allyl methacrylate = 94: 5.8: 0.2 (mass ratio) 245 parts by mass of the mixture was continuously dropped over 50 minutes, and after the completion of the dropping, a polymerization reaction was further performed for 30 minutes.
Next, 0.32 parts by mass of potassium peroxodisulfate was charged into the reactor and stirred for 5 minutes, and then butyl acrylate: styrene: allyl methacrylate = 80.6: 17.4: 2 (mass ratio). 315 parts by mass of the resulting monomer mixture was continuously dropped over 60 minutes, and after the completion of the dropping, the polymerization reaction was further performed for 30 minutes.
Subsequently, 0.14 parts by mass of potassium peroxodisulfate was charged into the reactor and stirred for 5 minutes, and then 140 parts by mass of a monomer mixture consisting of methyl methacrylate: methyl acrylate = 94: 6 (mass ratio). Was continuously supplied dropwise over 30 minutes, and after the completion of the dropwise addition, a polymerization reaction was further performed for 60 minutes to obtain acrylic elastic particles having a three-layer structure.

(3) Production of thermoplastic resin 80 parts by mass of the methacrylic resin synthesized in the above (1) and 20 parts by mass of the acrylic elastic particles having a three-layer structure synthesized in the above (2) were mixed with a Henschel mixer. A (meth) acrylic resin pellet was obtained using a vented twin-screw extruder with a screw diameter of 58 mm set at 260 ° C. The melt viscosity of the obtained (meth) acrylic resin was 830 Pa · s.

(Adjustment of the ratio {B / A} of the projected area B of the tapered portion of the wall surface in the flow direction to the projected area A of the portion of the wall surface excluding the outlet in the flow direction)
The wall surface of the housing of the filter device is cut so as to be inclined in a direction away from the inflow port provided at one end of the flow path as approaching the outflow port provided on the wall surface, and the flow direction of a portion of the wall surface excluding the outflow port The ratio {B / A} of the projected area B in the flow direction of the tapered portion provided on the wall surface to the projected area A on the wall was adjusted.

(Example 1)
A single-screw extruder with a 65 mmφ vent, a gear pump, a filter device equipped with four filter elements shown in FIG. 3, a static mixer, and a film manufacturing device equipped with a T-die in this order are provided with an extruder, a gear pump, and a housing for the filter device. The thermoplastic resin ((meth) acrylic resin) obtained in Production Example 1 was extruded under the conditions of a set temperature of 260 ° C. and a discharge rate of 165 kg / h, and a mirror-surface metal rigid roll and a mirror-surface metal set at 90 ° C. A film having a thickness of 100 μm was produced by being sandwiched between elastic rolls.
The filter device has a housing having an inlet and an outlet for molten resin to flow in and a wall having a ratio {B / A} adjusted as described above, and four candle-shaped filter elements in the housing. The one with was used.
The candle type filter element had a length of 360 mm, a diameter of 60 mm, a filtration accuracy of 10 μm, a total filtration area of four filter elements of 1.21 m ² , and a ratio {B / A} of 0.96.
Table 1 shows the evaluation results of the amount of foreign substances in the film obtained 10 hours after the start of film formation.

(Example 2)
A film having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the ratio {B / A} was changed to 0.85.
Table 1 shows the evaluation results of the amount of foreign substances in the film obtained 10 hours after the start of film formation.

(Example 3)
A film having a thickness of 100 μm was obtained in the same manner as in Example 2 except that the discharge rate of the extruder was changed to 200 kg / h.
Table 1 shows the evaluation results of the amount of foreign substances in the film obtained 10 hours after the start of film formation.

(Comparative Example 1)
A film having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the ratio {B / A} was changed to 0.25.
Table 1 shows the evaluation results of the amount of foreign substances in the film obtained 10 hours after the start of film formation.

(Comparative Example 2)
A film having a thickness of 100 μm was obtained in the same manner as in Comparative Example 1, except that the discharge rate of the extruder was changed to 200 kg / h.
Table 1 shows the evaluation results of the amount of foreign substances in the film obtained 10 hours after the start of film formation.

In Examples 1 to 3 using the filter device in which the ratio {B / A} satisfies 0.7 or more, the amount of foreign matters in the obtained film was small because there were few staying portions where the molten resin easily stayed in the housing. . On the other hand, in Comparative Examples 1 and 2 using the filter device in which the ratio {B / A} does not satisfy 0.7 or more, the amount of foreign matters in the obtained film is large because there are many staying portions where the molten resin easily stays in the housing. There were many.
In addition, when the filter device having the same ratio {B / A} is used, it can be seen that the shorter the residence time, the smaller the amount of foreign matter in the film (see Examples 2 and 3, and Comparative Examples 1 and 2).

REFERENCE SIGNS LIST 1 flow path 2 inflow port 3, 13 wall surface 4, 14 outflow port 5, 15 filter element 15 a slope of filter element 6 support member 7, 17 slope 7 a, 7 b, 7 c, 17 a, 17 b, 17 c slope area 8 Housing 10, 20 Filter device P A portion where the wall surface is not inclined or the angle between the wall surface and a plane perpendicular to the flow path direction is 10 ° or less even if the wall surface is inclined.

Claims (13)

A flow path for the fluid to be treated, an inlet provided at one end of the flow path, a wall provided at the other end of the flow path, and a housing having an outlet provided at the wall.
A filter element that covers the outlet and protrudes toward the flow path,
The wall surface is inclined continuously or discontinuously in a direction away from the inflow port as it approaches the outflow port side, and an angle formed by a plane perpendicular to the flow path direction exceeds 10 °. Part,
A filter device wherein a ratio {B / A} of a projected area B of the tapered portion in the flow direction to a projected area A of the portion of the wall surface excluding the outlet in the flow direction is 0.7 or more. .   The filter device according to claim 1, wherein the filtration accuracy of the filter element is 1 m or more and 50 m or less. A method for producing a thermoplastic resin molded article by a melt extrusion method,
Thermoplastic resin molding, comprising: disposing the filter device according to claim 1 between an extruder and a die, and passing a molten thermoplastic resin discharged from the extruder through the filter device. How to make the body.   The method for producing a thermoplastic resin molded article according to claim 3, wherein the residence time of the thermoplastic resin in the filter device is 50 seconds or more and 1,800 seconds or less.   The method for producing a thermoplastic resin molded product according to claim 3, wherein a set temperature of a housing of the filter device is 230 ° C. or more and 300 ° C. or less.   The method for producing a thermoplastic resin article according to any one of claims 3 to 5, wherein an initial pressure difference at the inflow port and the outflow port of the filter device is from 0.1 MPa to 10 MPa. The thermoplastic resin molding according to any one of claims 3 to 6, wherein a melt viscosity of the thermoplastic resin at a temperature of 270 ° C and a shear rate of 122 seconds ^-1 is 100 Pa · s or more and 1,500 Pa · s or less. How to make the body.   The method for producing a thermoplastic resin article according to any one of claims 3 to 7, wherein the thermoplastic resin contains a (meth) acrylic resin. The (meth) acrylic resin,
Homopolymer of methyl methacrylate (A);
Copolymer of methyl methacrylate and acrylate (C);
A mixture of a homopolymer (A) of methyl methacrylate and a homopolymer (B) of an acrylate ester;
Mixture of homopolymer (A) of methyl methacrylate and copolymer (C) of methyl methacrylate and acrylate;
The method for producing a thermoplastic resin article according to claim 8, wherein the method is selected from the group consisting of:   The method for producing a thermoplastic resin article according to any one of claims 3 to 9, wherein the thermoplastic resin contains rubber particles.   The method for producing a thermoplastic resin molded article according to any one of claims 3 to 10, wherein the thermoplastic resin molded article is a film.   The method for producing a thermoplastic resin article according to any one of claims 3 to 11, wherein the thermoplastic resin article is an optical article.   The method for producing a thermoplastic resin article according to any one of claims 3 to 11, wherein the thermoplastic resin article is a decorative article.