JP2017113368A - Resin sheet for driving nail, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet for driving a nail capable of suppressing cracks when washing a sheet surface into which nails driven.SOLUTION: A resin sheet for driving a nail is formed of a transparent thermoplastic resin. In the resin sheet for driving the nail, a thickness is 5-20 mm, and an absolute value of residual stress of a front layer part and a rear layer part, when viewed from a thickness direction, is 70 kg/cmor less. The resin is preferably a methacrylic resin (A) and/or a polycarbonate-based resin. The resin is a methacrylic resin (A), and further preferably contains an acrylic rubber (B).SELECTED DRAWING: None

Description

  The present invention relates to a nailing resin sheet and a method for producing the same.

In a ball game machine, nails for changing the falling direction of the game ball are driven into a plurality of holes (usually through holes) formed by NC (numerical control machining) processing or the like on the game board.
In recent years, in order to enhance the entertainment characteristics of ball game machines, a configuration in which a transparent resin sheet is used as a material for the game board and a lighting panel such as a liquid crystal display panel and / or an LED (light emitting diode) is combined. Has been.

Examples of the transparent resin include polycarbonate resins and methacrylic resins.
Since the polycarbonate-based resin sheet has a relatively low surface hardness, it tends to be easily damaged by friction with the game ball or collision of the game ball.
Since the methacrylic resin sheet has a relatively high surface hardness, it is difficult to be damaged even by friction with the game ball or collision of the game ball. However, general methacrylic resins have insufficient impact resistance, and there is a risk of resin cracking when nailing. Therefore, Patent Documents 1 and 2 disclose a resin sheet for nailing in which impact resistance is improved by adding acrylic rubber particles to a methacrylic resin in order to suppress resin cracking during nailing. (Claim 1 of Patent Document 1 and Claim 1 of Patent Document 2).

JP 2006-320705 A JP 2008-049137 A

In the conventional nail driving resin sheet, when the sheet surface on which the nail is driven is cleaned using a cleaning agent containing a solvent, the sheet surface may be cracked. This crack is particularly likely to occur around the nail.
Although the addition of acrylic rubber particles can improve the impact resistance of the resin sheet and suppress resin cracking during nailing, there are cases where cracking during cleaning of the sheet surface into which the nail is driven cannot be eliminated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin sheet for nailing that can suppress cracking during cleaning of the sheet surface on which the nail is driven.

The resin sheet for nailing of the present invention is
Made of transparent thermoplastic resin,
The thickness is 5-20 mm,
When viewed in the thickness direction, the resin sheet for nailing has an absolute value of residual stress of the surface layer portion and the back layer portion of 70 kg / cm ² or less.

The manufacturing method of the resin sheet for nailing of the present invention,
A method for producing the above-described nail-forming resin sheet of the present invention,
Extruding means for heating and melting the transparent thermoplastic resin and extruding it into a sheet,
A cooling roll unit composed of a plurality of cooling rolls arranged adjacent to each other and cooled while pressurizing the sheet-like material extruded by the extrusion molding means;
Using a manufacturing apparatus provided with a pair of take-up rolls that are arranged to face each other and express the force of taking up the manufactured resin sheet,
Adjusting the overall temperature of the resin sheet within a range of 115 to 165 ° C. at the time of leaving the cooling roll on the most downstream side of the plurality of cooling rolls of the cooling roll unit;
Among the plurality of cooling rolls of the cooling roll unit, when the peripheral speed of the second cooling roll located second from the upstream side is V2, and the peripheral speed of the pair of take-up rolls is VX,
Adjusting the ratio (VX / V2) of the peripheral speed VX of the pair of take-up rolls to the peripheral speed V2 of the second cooling roll within a range of 0.98 to 1.01;
Between the cooling roll unit and the pair of take-up rolls, the resin sheet is gradually cooled by passing through an environment adjusted in a range of 5 to 50 ° C.

In the present specification, the “main component” is defined as a component exceeding 50 mass%.
In this specification, the “sheet” is a plate-like object having no flexibility.
In this specification, the “front surface” of the nail driving resin sheet is the sheet surface on the side where the nail is driven, and the “back surface” is the sheet surface on the opposite side. Before hitting the nail, the front surface is one sheet surface, the back surface is the other sheet surface, and “front surface” and “back surface” are not clearly distinguished.
The “surface layer portion” refers to a portion from the surface to a depth of 0.5 mm. Similarly, the “back layer portion” refers to a portion from the back surface to a depth of 0.5 mm.

  In the present specification, unless otherwise specified, the “residual stress of the surface layer portion and the back layer portion of the resin sheet for nailing” is the residual stress of the surface layer portion and the back layer portion before nailing.

  In the present specification, unless otherwise specified, “residual stresses in the surface layer portion and the back layer portion” before and after nail driving are measured by the method described in the section “Examples”.

  In this specification, “weight average molecular weight (Mw) and number average molecular weight (Mn)” are values obtained by converting a chromatogram measured by gel permeation chromatography (GPC) into a molecular weight of standard polystyrene.

In this specification, unless otherwise specified, the “glass transition temperature (Tg)” is an intermediate glass transition temperature measured by the following method.
Using a differential scanning calorimeter (“DSC-50” manufactured by Shimadzu Corporation), the temperature of the sample was once raised to 230 ° C. and cooled to room temperature, and then increased again from room temperature to 230 ° C. at a rate of 10 ° C./min. The DSC curve is measured under the condition of raising the temperature at. An intermediate point obtained from the obtained DSC curve is defined as a glass transition temperature (Tg). When a plurality of shoulders appear in the DSC curve, the glass transition temperature (Tg) is determined based on the highest temperature side shoulder.

  ADVANTAGE OF THE INVENTION According to this invention, the resin sheet for nailing which can suppress the crack at the time of washing | cleaning of the sheet | seat surface in which the nail was nailed can be provided.

It is a schematic diagram which shows the manufacturing apparatus of the resin sheet for nailing of one Embodiment which concerns on this invention. 2 is a schematic perspective view of a resin sheet after forming a through hole in Example 1. FIG. 3 is a schematic perspective view of four cut samples in Example 1. FIG. 3 is a schematic perspective view of a resin sheet after nailing in Example 1. FIG. 3 is a schematic perspective view of a resin sheet after spraying a cleaning agent in Example 1. FIG. 3 is a schematic perspective view of a resin sheet after nailing and cleaning agent spraying in Example 1. FIG. It is explanatory drawing (schematic top view) of the measuring method of the residual stress in the comparative example 1.

"Plastic sheet for nailing"
The present invention relates to a nailing resin sheet (hereinafter sometimes simply referred to as “resin sheet” or “sheet”).
The nail driving application is not particularly limited, and examples thereof include a ball game machine.
In a ball game machine, nails for changing the falling direction of the game ball are driven into a plurality of holes (usually through holes) formed by NC (numerical control machining) processing or the like on the game board.
Other nailing applications include building materials such as resin sashes and joint materials.

  The nailing resin sheet of the present invention is made of a transparent thermoplastic resin. In this specification, unless otherwise specified, the “transparent thermoplastic resin” has a transparency of 80% or more of visible light (wavelength range: 360 to 830 nm) when processed into a 10 mm thick resin sheet. Resin.

Even under a temperature environment of 40 ° C. or higher, warping of the sheet and nail removal or change in the position of the nail are effectively suppressed. Therefore, the resin sheet for nailing of the present invention has a thickness t of 5 mm or more. is there.
If the thickness t is less than 5 mm, the sheet is likely to warp, particularly under a temperature environment of 40 ° C. or more, and this tends to cause nail removal or nail position change.
The upper limit of the thickness t is about 70 mm in view of sheet formability and the like.

In applications such as a ball game machine, the thickness t of the resin sheet for nailing of the present invention is preferably 5 to 30 mm, more preferably 5 to 20 mm.
In applications such as ball game machines, if the thickness t is less than 5 mm, the sheet tends to warp, particularly under a temperature environment of 40 ° C. or higher, and this tends to cause nail removal or nail position change. When the thickness t is more than 30 mm or more than 20 mm, the sheet becomes heavy and the handling property tends to be lowered.

In the nailing resin sheet of the present invention, the absolute value of the residual stress in the surface layer portion and the back layer portion is 70 kg / cm ² or less as viewed in the thickness direction.

The nailing resin sheet of the present invention is produced by a known molding method such as an extrusion molding method, a cast molding method, and an injection molding method.
Depending on the manufacturing method and manufacturing conditions, residual stress may remain in the surface layer portion and the back layer portion of the manufactured nailing resin sheet. The residual stress in the surface layer portion and the back layer portion is a compressive stress and / or a tensile stress.
As the residual stress in the surface layer portion and the back layer portion increases, when the sheet surface on which the nail is driven is cleaned using a cleaning agent containing a solvent, the sheet surface tends to be cracked. This crack is particularly likely to occur around the nail.
When the absolute value of the residual stress in the surface layer portion and the back layer portion is 70 kg / cm ² or less, it is possible to suppress cracks during cleaning of the sheet surface on which the nail is driven.
The absolute value of the residual stress in the surface layer portion and the back layer portion is preferably 65 kg / cm ² or less.

The nailing resin sheet is manufactured using a known sheet molding method such as an extrusion molding method, a cast molding method, and an injection molding method.
By devising the manufacturing method and manufacturing conditions, the absolute value of the residual stress in the surface layer portion and the back layer portion can be adjusted to 70 kg / cm ² or less, preferably 65 kg / cm ² or less.
The extrusion molding method is particularly preferable because the residual stress in the surface layer portion and the back layer portion can be effectively reduced. Specific preferred manufacturing conditions will be described later.

(Transparent thermoplastic resin)
The transparent thermoplastic resin is preferably a transparent resin such as a methacrylic resin (A) and a polycarbonate resin.
The methacrylic resin (A) is particularly preferred because it has a relatively high surface hardness and is not easily damaged by friction with the game ball or collision of the game ball.

  The methacrylic resin (A) contains a methacrylic polymer. The content of the methacrylic polymer in the methacrylic resin (A) is preferably 55 to 85% by mass, more preferably 70 to 85% by mass.

The methacrylic polymer includes a monomer unit derived from methyl methacrylate (MMA). The methacrylic polymer is preferably a linear polymer.
In the methacrylic polymer, the content of monomer units derived from methyl methacrylate (MMA) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and particularly preferably 90 to 100%. % By mass.
The methacrylic polymer can contain one or more monomer units in addition to the monomer unit derived from methyl methacrylate (MMA) as necessary.

  Examples of monomer units other than the monomer unit derived from methyl methacrylate (MMA) include, for example, methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, And (meth) acrylic acid alkyl esters such as 2-ethylhexyl (meth) acrylate.

  The methacrylic polymer preferably has an average degree of polymerization of 500 to 3000, more preferably 520 to 2500, and particularly preferably 550 to 2000.

The methacrylic resin (A) preferably has a weight average molecular weight (Mw) of 50,000 to 300,000, more preferably 52,000 to 250,000, and particularly preferably 55,000 to 200,000.
When the Mw of the methacrylic resin (A) and the average degree of polymerization of the methacrylic polymer are in the above ranges, a sheet having good mechanical properties such as toughness and impact resistance, a uniform thickness and excellent surface smoothness can be obtained. Easy to obtain.

  From the viewpoint of moldability, the methacrylic resin (A) has a melt flow rate (MFR) measured at 230 ° C. under a load of 3.8 kg in accordance with JIS K 7210, preferably 0.1 g / It is 10 minutes or more, more preferably 0.1 to 30 g / 10 minutes, particularly preferably 0.5 to 20 g / 10 minutes, and most preferably 1.0 to 10 g / 10 minutes.

From the viewpoint of moldability, the glass transition temperature (Tg) of the methacrylic resin (A) is preferably 100 ° C. or higher. The upper limit of the glass transition temperature (Tg) of the methacrylic resin (A) is usually 130 ° C. or lower.
The glass transition temperature (Tg) can be controlled by adjusting the molecular weight or the like.

The production method of the methacrylic resin (A) is not particularly limited, and a known polymerization method such as a radical polymerization method or an anionic polymerization method can be applied.
Solvent-free continuous radical polymerization and anionic polymerization methods are preferred from the viewpoint of obtaining a methacrylic resin having high heat decomposability, little foreign matter, and high transparency.
In the above known polymerization method, by adjusting the polymerization temperature, the polymerization time, the type or amount of the chain transfer agent, or the type or amount of the polymerization initiator, a methacrylic resin (A) having a desired Mw is obtained. Can be manufactured.

(Acrylic rubber (B))
In the nailing resin sheet of the present invention, when the transparent thermoplastic resin contains a methacrylic resin (A), the transparent thermoplastic resin preferably further contains an acrylic rubber (B).
The acrylic rubber (B) can improve the impact resistance of the resin sheet for nailing and suppress the resin cracking during nailing.
The acrylic rubber (B) is not particularly limited, and examples thereof include multilayer structured particles (BX) including at least one rubber layer, and a block copolymer (BY).
The acrylic rubber (B) preferably contains multilayer structure particles (BX) because the effect of improving impact resistance can be obtained effectively.

<Multilayer structured particles (BX)>
The multilayer structured particle (BX) including at least one rubber layer is an acrylic rubber particle having a so-called core-shell structure including a soft layer (rubber layer) and a hard layer.

If the addition amount of the multilayer structured particles (BX) is too small, the effect of improving the impact resistance cannot be obtained effectively, and there is a possibility that a resin crack occurs when nailing.
If the addition amount of the multilayer structured particles (BX) is excessive, the transparency and surface hardness of the resin sheet may be lowered.
Since the effect of improving impact resistance is effectively obtained and the transparency and surface hardness of the resin sheet are improved, the content of the multilayer structured particles (BX) is preferably 15% by mass or more, more preferably 15 to It is 45 mass%, More preferably, it is 15-30 mass%, Most preferably, it is 18-30 mass%, Most preferably, it is 20-30 mass%.

In the present specification, unless otherwise specified, the content of the multilayer structured particles (BX) is measured as follows.
One piece of the resin sheet is sufficiently dried to remove moisture, and then its mass (W1) is measured.
Next, the said sheet piece is put into a test tube, acetone is added and melt | dissolved, and an acetone soluble part is removed.
Then, acetone is removed using a vacuum heat dryer, and the mass (W2) of the residue is measured.
Based on the following formula, the content of the multilayer structured particles (BX) is determined.
[Content of multilayer structure particle (BX)] = (W2 / W1) × 100 (%)

  In addition, when the outermost layer of multilayer structure particle (BX) melt | dissolves in acetone, the compounding quantity of multilayer structure particle (BX) and the content calculated | required by the said measurement may not correspond. However, in this specification, it is assumed that the acetone insoluble portion is a rubber component contributing to impact resistance, and the content of the multilayer structure particles (BX) is obtained.

If the particle diameter of the multilayer structured particles (BX) in the sheet is too small, the effect of improving the impact resistance cannot be obtained, and there is a possibility that a resin crack occurs when nailing.
When the particle diameter of the multilayer structure particles (BX) in the sheet is excessive, the driven nail tends to come off easily, especially when the amount of the multilayer structure particles (BX) added is large.
Since the effect of improving impact resistance is effectively obtained and nail pulling is suppressed, the particle diameter of the multilayer structured particles (BX) in the sheet is preferably 0.05 to 0.3 μm.

In the present specification, unless otherwise specified, the average particle size of the polymer particles in the latex containing the polymer particles is measured using a light scattering photometer DLS-600 manufactured by Otsuka Electronics Co., Ltd.
The average particle diameter in the latex of the polymer particles is determined by measuring by a dynamic light scattering method using a sample collected from the latex after the completion of polymerization, and analyzing by a cumulant method.

In the present specification, unless otherwise specified, the average particle diameter of the multilayer structured particles (BX) in the sheet is determined by cross-sectional observation with a transmission electron microscope (TEM).
Specifically, a part of the resin sheet is cut out, cut in the thickness direction with a microtome under freezing conditions, the obtained section is dyed with ruthenic acid, and the cross section of the dyed rubber particles is observed with a TEM. . The average value of 100 particles is defined as the average particle size.

As multilayer structure particles (BX),
The outermost layer is a hard layer containing 40 to 100% by mass of at least one methacrylate unit and 0 to 60% by mass of another monomer unit that can be copolymerized as necessary,
At least one inner layer (layer inside the outermost layer) is at least one acrylate unit unit of 40 to 99.9% by mass, and, if necessary, other monomer units of 0 to 60% by mass, And the multilayer structure particle (BX-1) which is a soft layer (rubber layer) containing 0.1-5 mass% of polyfunctional monomer units is preferable.

  In the present specification, the “polyfunctional monomer” is a crosslinking agent (crosslinkable monomer) containing two or more polymerizable functional groups.

  The hard layer constituting the outermost layer of the multilayer structured particle (BX-1) preferably has a glass transition temperature (Tg) of 25 ° C. or higher when the layer is formed alone from the viewpoint of heat resistance. . In addition, at least one inner layer is composed of a soft layer (rubber layer), and from the viewpoint of impact resistance, the glass transition temperature (Tg) when the soft layer is formed alone may be less than 25 ° C. preferable.

  The ratio of the outermost layer in the acrylic multilayer structure particles (BX-1) is not particularly limited, but in order to ensure good dispersibility during melt-kneading with the methacrylic resin (A), 10 to 80% by mass. It is preferable to be within the range.

  The monomer for the hard layer of the acrylic multilayer structure particle (BX-1) preferably contains methyl methacrylate from the viewpoint of transparency.

If necessary, a polyfunctional monomer that is a copolymerizable unsaturated monomer and / or a crosslinking agent can be used for the hard layer according to the methacrylic acid ester.
Examples of copolymerizable unsaturated monomers include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and benzyl acrylate.
These can be used alone or in combination of two or more.

  Examples of the polyfunctional monomer include allyl (meth) acrylate, ethylene glycol di (meth) acrylate, divinylbenzene and the like. These can be used alone or in combination of two or more.

  As a monomer for the soft layer (rubber layer) of the acrylic multilayer structure particle (BX-1), from the viewpoint of impact resistance, an acrylate ester, another monomer copolymerizable as necessary, And multifunctional monomers are used.

Examples of the acrylate ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and benzyl acrylate. These can be used alone or in combination of two or more.
The acrylate ester used for the soft layer (rubber layer) preferably contains butyl acrylate and / or 2-ethylhexyl acrylate.

  Examples of other monomers copolymerizable with acrylic acid esters include diene compounds such as 1,3-butadiene and isoprene; aromatic vinyl compounds such as styrene, vinyltoluene, and α-methylstyrene. These can be used alone or in combination of two or more.

  As a polyfunctional monomer, the same thing as the said hard layer is mentioned.

  The multilayer structure of the acrylic multilayer structure particles (BX-1) is optional as long as the outermost layer is a hard layer and at least one inner layer is a soft layer. As the multilayer structure, from the inner layer to the outer layer, a soft layer-hard layer two-layer structure, a hard layer-soft layer-hard layer three-layer structure, a soft layer-hard layer-soft layer-hard layer And a four-layer structure of hard layer-soft layer-soft layer-hard layer.

  The acrylic multilayer structure particle (BX-1) can be produced by a known emulsion polymerization method. First, one or two or more kinds of raw material monomers are emulsion-polymerized to form core particles, and then one or two or more other monomers are emulsion-polymerized in the presence of the core particles to form core particles. Form a shell around. Next, if necessary, one or more monomers are further emulsion-polymerized in the presence of particles consisting of a core and a shell to form another shell. By repeating such a polymerization reaction, the target acrylic multilayer structure particles (BX-1) can be produced as an emulsified latex.

  A known surfactant can be used for the emulsion polymerization. The surfactant can be selected according to the purpose from the viewpoint of the stability of the polymerization system and the particle diameter of the acrylic multilayer structure particles to be produced. As the surfactant, an anionic surfactant is preferable.

  Examples of anionic surfactants include carboxylates such as sodium stearate, sodium myristate, and sodium N-lauroyl sarcosinate.

  The polymerization initiator used in the emulsion polymerization is not particularly limited, and examples thereof include inorganic peroxides such as potassium persulfate and ammonium persulfate.

  A chain transfer agent can be used for emulsion polymerization as needed. Examples of the chain transfer agent include alkyl mercaptans such as n-dodecyl mercaptan, n-lauryl mercaptan, tert-dodecyl mercaptan, and sec-butyl mercaptan.

  The acrylic multilayer structure particles (BX-1) are produced by emulsion polymerization, and can be recovered as a powdered polymer by coagulation, dehydration, drying and the like by a known method.

<Block copolymer (BY)>
The block copolymer (BY) is not particularly limited, and a methacrylic ester polymer block (b1) mainly composed of a methacrylic ester such as methyl methacrylate and an acrylic based mainly on an acrylate ester such as butyl acrylate. A block copolymer (BY-1) containing an acid ester polymer block (b2) is preferred. The number of the methacrylic ester polymer block (b1) in the block copolymer (BY) is not particularly limited, and may be singular or plural. Similarly, the number of acrylic ester polymer blocks (b2) in the block copolymer (BY) is not particularly limited, and may be one or more.

(Optional component)
The nailing resin sheet of the present invention can contain optional components other than those described above, if necessary.
The nailing resin sheet of the present invention can contain one or more other resins.
The nailing resin sheet of the present invention can contain one or more additives.

  Other resins include silicone rubbers; styrene thermoplastic elastomers such as SEPS, SEBS, and SIS; and olefinic rubbers such as IR, EPR, and EPDM.

  The amount of other resin that can be contained in the nailing resin sheet of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and most preferably 0% by mass.

  Additives include lubricants, UV absorbers, fillers, antioxidants, thermal degradation inhibitors, light stabilizers, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes and pigments, light diffusing agents, Organic dyes, matting agents, phosphors and the like can be mentioned.

In applications such as ball game machines, cutting processing for cutting a resin sheet into a predetermined shape using a saw or the like for a resin sheet for nailing, a hole for nailing and various game members using a drill, etc. A drilling process for opening a mounting hole and an outer shape process for adjusting the shape using a router or the like are performed.
The lubricant is a component that imparts lubricity to the resin sheet and lowers the coefficient of friction of the resin sheet. By adding this component, the resin sheet can be combined with the resin sheet by a lubricating effect in processing such as cutting or perforating the resin sheet. The frictional heat with the tool can be suppressed, and the deterioration of the appearance quality of the processed surface of the resin sheet and the resin fusion to the tool can be suppressed.

  Examples of the lubricant include hydrocarbons, fatty acids, aliphatic alcohols, fatty acid esters, fatty acid amides, and metal soaps. These can use 1 type (s) or 2 or more types.

As the fatty acid used as the lubricant, fatty acids having 12 or more carbon atoms such as lauric acid, palmitic acid, stearic acid, behenic acid, oleic acid, and erucic acid are preferable. Among these, fatty acids having 16 to 24 carbon atoms such as palmitic acid, stearic acid, behenic acid, oleic acid, and erucic acid are more preferable, and saturation with 16 to 24 carbon atoms such as palmitic acid, stearic acid, and behenic acid. Fatty acids are particularly preferred.
The aliphatic alcohol used as a lubricant is more preferably a saturated aliphatic alcohol having 12 to 18 carbon atoms such as lauryl alcohol, palmityl alcohol, and stearyl alcohol, and 16 to 18 carbon atoms such as palmityl alcohol and stearyl alcohol. The saturated aliphatic alcohol is particularly preferred.

  The fatty acid ester used as a lubricant is preferably an ester (including a partial ester) of a monovalent or polyhydric (divalent or higher) alcohol containing the fatty acid and the aliphatic alcohol, and a fatty acid having 16 to 22 carbon atoms. Fatty acid monoglyceride which is a partial ester with glycerin is more preferable.

  Examples of fatty acid amides used as lubricants include amides and bisamides of the above fatty acids. Such fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxyl stearic acid amide, oleic acid amide, erucic acid amide, N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N -Stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide, methylene bis stearic acid amide, methylene bis capric acid amide, ethylene bis lauric acid amide, etc. are mentioned.

The ultraviolet absorber is a compound having an ability to absorb ultraviolet rays. The ultraviolet absorber is a compound that is said to have a function of mainly converting light energy into heat energy.
Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, succinic anilides, malonic esters, and formamidines.
These can use 1 type (s) or 2 or more types.
Among these, benzotriazoles, triazines, or ultraviolet absorbers having a maximum molar extinction coefficient ε _{max at a} wavelength of 380 to 450 nm of 1200 dm ³ · mol ⁻¹ cm ⁻¹ or less are preferable.

  Benzotriazoles are highly effective in suppressing deterioration of optical properties such as coloring due to ultraviolet irradiation. Examples of benzotriazoles include 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF; trade name TINUVIN329), 2- (2H- Benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234) and 2,2′-methylenebis [6- (2H-benzotriazole 2-yl) -4-tert-octylphenol] (manufactured by ADEKA; LA-31) and the like are preferable.

An ultraviolet absorber having a maximum molar extinction coefficient ε _{max at a} wavelength of 380 to 450 nm of 1200 dm ³ · mol ⁻¹ cm ⁻¹ or less can suppress yellowness of the resulting molded article. Examples of such an ultraviolet absorber include 2-ethyl-2′-ethoxy-oxalanilide (manufactured by Clariant Japan, trade name: Sundebore VSU).

  Among the above-described ultraviolet absorbers, benzotriazoles and the like are preferably used from the viewpoint that resin degradation due to ultraviolet irradiation can be suppressed.

  Further, when it is desired to efficiently absorb a wavelength around 380 nm, a triazine ultraviolet absorber is preferably used. Examples of such ultraviolet absorbers include 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (manufactured by ADEKA; LA-F70), and Examples thereof include hydroxyphenyltriazine-based ultraviolet absorbers (manufactured by BASF; TINUVIN477-D and TINUVIN460).

  The antioxidant alone has an effect of preventing oxidative deterioration of the resin in the presence of oxygen. Examples thereof include phosphorus antioxidants, hindered phenol antioxidants, and thioether antioxidants. These antioxidants can be used alone or in combination of two or more. Among these, from the viewpoint of the effect of preventing deterioration of optical properties due to coloring, a phosphorus-based antioxidant and a hindered phenol-based antioxidant are preferable, and a combined use of a phosphorus-based antioxidant and a hindered phenol-based antioxidant is more preferable. .

  Examples of phosphorus antioxidants include 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite (manufactured by ADEKA; trade name: ADK STAB HP-10), tris (2,4-dit -Butylphenyl) phosphite (manufactured by BASF; trade name: IRGAFOS168) and 3,9-bis (2,6-di-tert-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3 , 9-diphosphaspiro [5.5] undecane (manufactured by ADEKA; trade name: ADK STAB PEP-36) and the like.

  As the hindered phenol-based antioxidant, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name: IRGANO01010), and octadecyl-3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF; trade name IRGANO01076) is preferred.

The thermal degradation inhibitor can prevent thermal degradation of the resin by scavenging polymer radicals generated when exposed to high heat in a substantially oxygen-free state.
As the thermal degradation inhibitor, 2-t-butyl-6- (3′-t-butyl-5′-methyl-hydroxybenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumilyzer GM), and 2,4-di-t-amyl-6- (3 ′, 5′-di-t-amyl-2′-hydroxy-α-methylbenzyl) phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumitizer GS) preferable.

As the polymer processing aid, polymer particles having a particle diameter of 0.05 to 0.5 μm, usually produced by an emulsion polymerization method, are used. Such polymer particles may be single layer particles composed of a single composition and single intrinsic viscosity polymer, or may be multilayer particles composed of two or more polymers having different compositions or intrinsic viscosities. .
In particular, particles having a two-layer structure having a polymer layer having a relatively low intrinsic viscosity in the inner layer and a polymer layer having a relatively high intrinsic viscosity of 5 dl / g or more in the outer layer are preferable.
The average degree of polymerization of the polymer processing aid is preferably 3,000 to 40,000.

  The total amount of additives that can be contained in the nailing resin sheet of the present invention is preferably 7% by mass or less, more preferably 5% by mass or less, and particularly preferably 4% by mass or less.

(Manufacturing method of resin sheet for nailing)
The nailing resin sheet of the present invention is produced by a known molding method such as an extrusion molding method, a cast molding method, and an injection molding method.
As described above, since the internal residual stress and the residual stress difference between the front and back surfaces can be effectively reduced, the extrusion molding method is preferable.

  The method for producing a nailing resin sheet of the present invention preferably includes an extrusion process (1) in which a transparent thermoplastic resin is heated and melted and extruded into a sheet shape.

<Step (1)>
With reference to drawings, the structure of the manufacturing apparatus of the resin sheet of one Embodiment concerning this invention and a manufacturing method using the same are demonstrated. FIG. 1 is a schematic diagram of a manufacturing apparatus.

As shown in FIG. 1, the resin sheet manufacturing apparatus 1 includes an extrusion molding unit 110 that heat-melts a raw material transparent thermoplastic resin 210M and extrudes it into a sheet shape.
In this embodiment,
The extrusion means 110 is
A raw material charging part 111 such as a hopper into which the raw material transparent thermoplastic resin 210M is charged;
A screw portion 112 for melting and extruding the transparent thermoplastic resin 210M, and extruding;
It is an extruder with a T die provided with a T die 113 including a discharge port 113A for discharging the heated and melted transparent thermoplastic resin 210M into a sheet shape.

  The temperature of the resin sheet 210 discharged from the T die 113 is preferably 160 to 270 ° C, more preferably 220 to 260 ° C.

The nail driving resin sheet manufacturing apparatus 1 also adds a sheet-like material that is disposed adjacent to each other with a separation portion having a separation distance corresponding to a desired thickness of the resin sheet 210 and extruded by the extrusion molding means 110. It has the cooling roll unit 120 which consists of several cooling rolls cooled while pressing.
The cooling roll unit 120 includes at least a first cooling roll 121 and a second cooling roll 122 having a separation portion below the discharge port 113 </ b> A of the T die 113.

  The sheet-like material extruded from the T-die 113 is sandwiched between the first cooling roll 121 and the second cooling roll 122, pressurized and cooled, and becomes a resin sheet 210. At this time, the resin sheet 210 is not sufficiently cooled and is not completely solidified.

In the illustrated example, the cooling roll unit 120 includes a first cooling roll 121, a second cooling roll 122, a third cooling roll 123, and a fourth cooling roll 124.
The obtained resin sheet 210 sandwiched between the first cooling roll 121 and the second cooling roll 122 and pressurized and cooled is separated from the first cooling roll 121 by the second cooling roll 122. It is cooled while passing on the surface, and is supplied between the second cooling roll 122 and the third cooling roll 123 and pressurized.
The resin sheet 210 is further cooled while passing on the surface of the third cooling roll 123 away from the second cooling roll 122, and is provided between the third cooling roll 123 and the fourth cooling roll 124, Pressurized.
The resin sheet 210 is further cooled while passing through the surface of the fourth cooling roll 124 away from the third cooling roll 123 and then moves away from the fourth cooling roll 124 and proceeds to the next step. At this point, the resin sheet 210 has not been sufficiently cooled and has not completely solidified.

In the present embodiment, the T die 113 and the cooling roll unit 120 of the extrusion molding unit 110 are disposed in the first manufacturing chamber R1.
The environmental temperature T1 in the first manufacturing chamber R1 is not particularly adjusted, and is, for example, about 35 to 40 ° C. higher than normal temperature (20 to 25 ° C.) due to the presence of the heated and melted transparent thermoplastic resin 210M.

In the present embodiment, a second manufacturing chamber R2 is provided adjacent to the first manufacturing chamber R1.
The environmental temperature T2 in the second manufacturing chamber R2 is adjusted within the temperature range described below in order to gradually cool the resin sheet 210 obtained by being pressurized and cooled by the cooling roll unit 120.
The environmental temperature T2 in the second manufacturing room R2 can be adjusted using a known air conditioner or the like.

The nail driving resin sheet manufacturing apparatus 1 also includes a protective film bonding means 130 for bonding the protective film 220 to the front and back surfaces of the manufactured resin sheet 210.
The protective film sticking means 130 includes a first protective film roll 131 that supplies the protective film 220 to the surface of the resin sheet 210, and a second protective film roll 132 that supplies the protective film 220 to the back surface of the resin sheet 210. Including.
The protective film sticking means 130 is provided outside the second manufacturing chamber R2.
Since the resin sheet 210 after being gradually cooled in the second manufacturing room R2 is sufficiently cooled and sufficiently solidified, the attaching process of the protective film 220 needs to adjust the environmental temperature in particular. Absent.

  The nail driving resin sheet manufacturing apparatus 1 also includes a pulling means 140 that expresses a force to pull the manufactured resin sheet 210. The take-up means 140 includes a pair of take-up rolls 141 and 142 that are arranged vertically so as to face each other with a separation portion having a separation distance corresponding to a desired thickness of the resin sheet 210.

The nailing resin sheet manufacturing apparatus 1 also includes a known cutting means (not shown) for cutting the resin sheet 210 having the protective film 220 attached on both sides into a plate shape.
In addition, the structure of the manufacturing apparatus 1 of the nailing resin sheet of this embodiment is only an example, and can change a design suitably.

The resin sheet 210 is manufactured as follows by using the manufacturing apparatus 1 for a nail driving resin sheet of the present embodiment.
First, the raw transparent thermoplastic resin 210M is heated and melted by the extrusion molding means 110 and extruded into a sheet shape.
Next, the cooling roll unit 120 pressurizes and cools the sheet-like material extruded by the extrusion molding unit 110 to obtain a resin sheet 210.
Next, the obtained resin sheet 210 is gradually cooled in the second manufacturing chamber R2.
Next, the protective film 220 is attached to both surfaces of the resin sheet 210 by the protective film attaching means 130.

In the above-mentioned extrusion molding method, the present inventors define the following three manufacturing conditions (manufacturing conditions 1 to 3) within a suitable range among a number of manufacturing conditions, whereby the surface layer portion and the back layer portion. It has been found that the absolute value of the residual stress can be adjusted to 70 kg / cm ² or less, preferably 65 kg / cm ² or less.
In the case where the post-process (2) is performed, the absolute value of the residual stress in the surface layer portion and the back layer portion is 70 kg / cm ² or less, preferably 65 kg / cm, regardless of whether the following production conditions 1 to 3 are satisfied. It can be adjusted to ² or less.

  In the present embodiment, as the manufacturing condition 1, the temperature TS of the entire resin sheet 210 is set to 115 at the time when the cooling roll unit 120 moves away from the cooling roll (the fourth cooling roll 124 in the example shown in FIG. 1). It adjusts in the range of -165 degreeC, Preferably it is 120-160 degreeC.

If the temperature TS of the resin sheet 210 at a time point away from the cooling roll at the most downstream side of the cooling roll unit 120 (the fourth cooling roll 124 in the example shown in FIG. 1) is less than 115 ° C., the residual stress in the surface layer portion and the back layer portion The absolute value of tends to increase. This is presumably because the surface of the resin sheet 210 in the cooling roll unit 120 tends to be rapidly cooled.
When the temperature of the resin sheet 210 at the time of moving away from the cooling roll at the most downstream side of the cooling roll unit 120 (the fourth cooling roll 124 in the example shown in FIG. 1) exceeds 165 ° C., the surface smoothness of the obtained nailing resin sheet is obtained. Tend to decrease.

  In this embodiment, at the time of leaving from the most downstream cooling roll of the cooling roll unit 120, the cooling roll is set so that the entire temperature TS of the resin sheet 210 is within a range of 115 to 165 ° C, preferably 120 to 160 ° C. The number of cooling rolls used in the unit 120 and the temperature of each cooling roll are set. The number of cooling rolls is preferably 3-4. As for the temperature of each cooling roll, 70-110 degreeC is preferable.

  The temperature of the resin sheet 210 on the production line can be measured by a known method. For example, the surface temperature of the resin sheet 210 can be measured using a non-contact thermometer such as an infrared radiation thermometer. .

  In the cooling roll unit 120, the peripheral speed of the first cooling roll 121 is V1, the peripheral speed of the second cooling roll 122 is V2, the peripheral speed of the third cooling roll 123 is V3, and the fourth cooling roll The peripheral speed of 124 is set to V4. The peripheral speed of the pair of take-up rolls 141 and 142 is VX. In order to smoothly take out the resin sheet 210, VX is usually set equal to or higher than V1 to V4. The temperature of the resin sheet 210 passing between the pair of take-up rolls 141 and 142 is lower than the temperature of the resin sheet 210 passing through the cooling roll unit 120. In consideration of the thermal contraction amount of the temperature difference resin sheet 210, VX may be set slightly lower than V1 to V4.

In this embodiment, as the manufacturing condition 2, the ratio of the peripheral speed VX of the pair of take-up rolls 141 and 142 to the peripheral speed V2 of the second cooling roll 122 (peripheral speed ratio VR = VX / V2) is 0.98 to 1. 01, preferably within the range of 0.99 to 1.01.
Moreover, in this embodiment, as manufacturing conditions 3, environmental temperature T2 of 2nd manufacturing chamber R2 between the cooling roll unit 120 and a pair of take-up rolls 141 and 142 is 5-50 degreeC, Preferably it is 20-50 degreeC. Adjust the temperature within the range.
By satisfying the production conditions 2 and 3, the absolute value of the residual stress in the surface layer portion and the back layer portion can be adjusted to 70 kg / cm ² or less, preferably 65 kg / cm ² or less.

When the peripheral speed ratio VR (VX / V2) exceeds 1.01 and the environmental temperature T2 of the second manufacturing chamber R2 is less than 5 ° C., the residual tensile stress in the flow direction tends to increase.
This is presumed to be due to the following reason.
When the peripheral speed ratio VR exceeds 1.01, the tensile stress applied to the resin sheet 210 tends to increase. In addition, when the environmental temperature T2 in the second manufacturing chamber R2 is less than 5 ° C., the temperature of the resin sheet 210 passing through the second manufacturing chamber R2 is lowered similarly to the environmental temperature T2. There is a tendency for thermal shrinkage to increase and tensile stress in the flow direction to increase.

When the peripheral speed ratio VR (VX / V2) is less than 0.98, the surface smoothness of the resin sheet 210 tends to decrease. When the peripheral speed ratio VR is less than 0.98, the surface shape unevenness is caused by a change in position when the resin sheet 210 is peeled from the most downstream cooling roll (fourth cooling roll 124 in the example shown in FIG. 1). May occur. This surface shape unevenness is generally called “chatter mark”.
When the environmental temperature T2 of the second manufacturing room R2 exceeds 50 ° C., the nail driving resin sheet is not efficiently cooled, and the manufacturing efficiency tends to be poor.

<Step (2)>
The method for producing a resin sheet for nailing according to the present invention further comprises, after step (1) (extrusion molding step), at a temperature higher than room temperature (20 to 25 ° C.) with respect to the obtained resin sheet. A step (2) of heating at a temperature lower than the glass transition temperature (Tg) of the resin can be included. In the step (2), for example, the protective film 220 is attached to both surfaces of the resin sheet 210 obtained after the step (1) (extrusion molding step), and further preferably cut to a length of 0.5 to 5 m. Can be implemented.
The resin sheet may be cut after step (2).

The present inventors carry out the step (2) after the step (1) regardless of the satisfaction of the production conditions 1 to 3 in the step (1), so that the absolute values of the residual stresses in the surface layer part and the back layer part are obtained. Has been found to be able to be adjusted to 70 kg / cm ² or less, preferably 65 kg / cm ² or less.
The heating method is not particularly limited, and examples include an infrared method, a warm air method, and an electric heater method. A plurality of heating methods may be combined.
The heating temperature in this step is preferably 60 to 100 ° C.
The heating time in this step is not particularly limited and is determined according to the heating temperature, and is preferably 5 minutes to 60 minutes.
In order to maintain the reduced residual stress, the resin sheet after the heat treatment is preferably cooled (including natural cooling) in an environment where no stress is generated. For example, the resin sheet after the heat treatment is preferably naturally cooled in a stationary state in an environment of 25 to 30 ° C.
As described above, the plate-like resin sheet 210 is manufactured.

  As described above, according to the present invention, it is possible to provide a resin sheet for nailing that can suppress cracking during cleaning of the sheet surface on which the nail is driven.

  Examples and comparative examples according to the present invention will be described.

Example 1
<Production of Acrylic Three-Layer Structure Particle (BX-1a)>
In a reactor equipped with a reflux condenser, 145 parts by mass of ion-exchanged water, 0.45 parts by mass of sodium stearate (SS), 0.08 parts by mass of sodium lauryl sarcosinate (LSS), and 0.05% of sodium carbonate (SC) After adding parts by mass and stirring and dissolving, 32.9 parts by mass of methyl methacrylate (MMA), 2.1 parts by mass of methyl acrylate (MA), and allyl methacrylate (ALMA) 0.07 as a crosslinking agent. A mass part was added and the temperature was raised to 80 ° C. while stirring. Next, 1.8 parts by mass of a 2% potassium persulfate aqueous solution was added, and the temperature was raised to 80 ° C. and held for 60 minutes to obtain a latex.
In the presence of the latex, 2.2 parts by mass of a 2% aqueous potassium persulfate solution was added, and 36.99 parts by mass of butyl acrylate (BA), 8.01 parts by mass of styrene (ST), and methacryl as a crosslinking agent. A monomer mixture consisting of 0.9 parts by mass of allyl acid (ALMA) was continuously added over 60 minutes, and held for 30 minutes after completion of the addition.
Next, 1.0 part by mass of a 2% aqueous potassium persulfate solution was added in the presence of the latex, 18.8 parts by mass of methyl methacrylate (MMA), 1.2 parts by mass of methyl acrylate (MA), and n-octyl mercaptan. (N-OM) A monomer mixture consisting of 0.04 parts by mass was continuously added over 30 minutes, and held for 60 minutes after completion of the addition.
As described above, an acrylic having an average particle diameter of 0.23 μm, which is composed of a hard layer (first layer), a soft layer (second layer, rubber layer), and a hard layer (third layer) from the center side. A latex containing 40% by mass of system three-layer structured particles (BX-1a) was obtained.
The monomer composition of each layer and the mass ratio of each layer of the resulting acrylic three-layer structured particle (BX-1a) are as shown in Table 1.

<Manufacture of raw material resin>
For dispersing the acrylic three-layer structure particles (BX-1a) obtained in Production Example 1, 90 mass parts of MMA and 10 mass parts of MA are obtained by emulsion polymerization, and the average particle diameter is 0.13 μm. A latex of the first methacrylic resin (A-1) having a polymerization degree of 960 was prepared.
A latex obtained by mixing the acrylic three-layer structured particle (BX-1a) latex obtained in Production Example 1 and the first methacrylic resin (A-1) latex at a mass ratio of 67:33 is coagulated by a known method. Filtration, washing, dehydration and drying yielded a first impact-resistant methacrylic resin (C-1). The MFR (melt flow rate) of the first impact-resistant methacrylic resin (C-1) was 1.5 g / 10 minutes.

  Separately, a powdery second methacrylic resin (A-2) obtained by suspension polymerization of 94 parts by mass of MMA and 6 parts by mass of MA and having a polymerization degree of 1550 was prepared. The MFR of the second methacrylic resin (A-2) was 1.3 g / 10 minutes.

Using a mixer mixer manufactured by Kubota Corporation, the first impact-resistant methacrylic resin (C-1) and the second methacrylic resin (A-2) were mixed in a mass ratio of 43:57. The mixture was melt-mixed to obtain a second impact-resistant methacrylic resin (C-2). This second impact-resistant methacrylic resin (C-2) was used as a raw material resin for the resin sheet.
Content C of acrylic three-layer structure particles (BX-1a) in the second impact-resistant methacrylic resin (C-2) was 23% by mass.

<Manufacture of resin sheet>
Using the above-obtained second impact-resistant methacrylic resin (C-2), using a production apparatus as shown in FIG. 1 and having polymethyl methacrylate (PMMA) as a main component, a sheet thickness t A methacrylic resin sheet having a thickness of 10 mm was extruded.
As the extrusion molding means 110, a 150 mmφ single screw extruder manufactured by Toshiba Machine Co., Ltd. was used.
By adjusting the temperature of the second cooling roll 122 and the fourth cooling roll 124, the overall temperature of the methacrylic resin sheet at the time of leaving from the most downstream cooling roll (in this example, the fourth cooling roll 124) TS was adjusted to 140 ° C.
The environmental temperature (environment temperature between the cooling roll unit and the pair of take-up rolls) T2 of the second manufacturing chamber R2 was 25 ° C.
The ratio of the peripheral speed VX of the pair of take-up rolls 141 and 142 to the peripheral speed V2 of the second cooling roll 122 (peripheral speed ratio VR = VX / V2) was 1.00.

  When the cross section of the obtained resin sheet was observed using TEM, the average particle diameter of the rubber layer of the acrylic three-layer structured particles (BX-1a) in the sheet was 0.21 μm.

Table 2 shows the main production conditions.
Each abbreviation in Table 2 is as follows.
PMMA: polymethyl methacrylate,
PC: Polycarbonate,
C: Content of acrylic three-layer structure particles (BX-1a) in the raw material resin,
t (mm): thickness of the produced resin sheet,
TS: the overall temperature of the resin sheet at the time of leaving the most downstream cooling roll,
VR: ratio of the peripheral speed VX of the pair of take-up rolls 141 and 142 to the peripheral speed V2 of the second cooling roll 122 (peripheral speed ratio, VX / V2),
T2: Environmental temperature of the second manufacturing chamber R2 (environment temperature between the cooling roll unit and the pair of take-up rolls).

After melt extrusion molding, the methacrylic resin sheet was cut to prepare four plate-shaped resin sheets having a length of 530 mm, a width of 470 mm, and a thickness of 10 mm.
As shown in FIG. 2, drilling using a drilling machine was performed on each plate-like resin sheet 11.
Four through holes 11H were formed at equal intervals in the longitudinal direction with respect to each resin sheet 11 using a drill having a diameter of 1.73 mmφ. The hole positions of the four resin sheets 11 were the same.
FIG. 2 is a schematic perspective view of a resin sheet in which four through holes are formed.
Four resin sheets 11 formed with four through holes 11H were subjected to the following evaluation.

<Measurement of residual stress in surface layer and back layer before nailing>
First, the residual stress of the surface layer portion and the back layer portion before nailing was measured for one resin sheet 11 in which four through holes 11H were formed.
As shown in FIG. 3, a square sample of 1 cm square in plan view was cut out in the thickness direction from one resin sheet 11 having four through holes 11H around each through hole 11H. Four cut samples 12A to 12D, and the size of each cut sample is 1 cm long × 1 cm wide × 10 mm thick).
FIG. 3 is a schematic perspective view of a total of four cut samples.
Note that sample cutting was performed as follows in order to prevent processing distortion.
Using a low-speed cutting machine “MC-201N” manufactured by Marto Co., Ltd. equipped with a diamond blade, cutting was performed in the “low-speed rotation / low-speed feeding” mode while cooling with cooling water of about 25 ° C. At this time, the blade was fed by the weight of the sample.
As shown in the figure, the cutting direction was parallel to the sheet extrusion direction (longitudinal direction) or the sheet width direction (short direction).
In each of the cut samples 12A to 12D, the residual stress of the surface layer portion and the back layer portion was measured from the side surface in the sheet extrusion direction and the sheet width direction.
In FIG. 3, the measurement direction is schematically shown by a thick arrow.
Using a Babinet corrector type precision strain gauge using a sodium light source (“Toshiba Strain Tester SVP-30-II” manufactured by Toshiba Glass Co., Ltd.) The retardation R of the surface layer part and the back layer part was measured, and the residual stress of the surface layer part and the back layer part was calculated based on the following formula.
Residual stress = R / (3.8 × T)
(In the above formula, R is retardation and T is sheet thickness (cm). 3.8 is the photoelastic constant of polymethyl methacrylate (PMMA) ((nm / cm) / (kg / cm ² )).)
As the residual stress of the surface layer portion, a maximum value of 55 kg / cm ² out of a total of 8 measured values obtained by measuring the four cut samples 12A to 12D in the sheet extrusion direction and the sheet width direction, It was set as the residual stress of the surface layer part.
Similarly, the maximum value of 55 kg / cm ² among the total of eight measured values obtained by measuring the four cut samples 12A to 12D in the sheet extrusion direction and the sheet width direction as the residual stress in the back layer portion, respectively. The residual stress in the back layer of this sheet was taken as the residual stress.

<Measurement of residual stress in surface layer and back layer after nailing>
Next, the residual stress of the surface layer portion and the back layer portion after nailing was measured for another resin sheet 11 in which the four through holes 11H were formed.
As shown in FIG. 4, for each through hole 11H of each resin sheet 11, "Autograph AG-2000B" manufactured by Shimadzu Corporation is used, and a brass screw nail round tip at a speed of 500 mm / min. (1.85 mmφ diameter, length of the portion excluding the nail head 26.5 mm, length of the screw portion 5.5 mm) was driven by the depth of the sheet thickness.
In FIG. 4, reference numeral 13 denotes a nail.

For each of the four nail driven parts, the surface layer part was observed by the sensitive color plate method using “Toshiba Strain Tester SVP-10-II” manufactured by Toshiba Glass Co., Ltd., and the correlation between the observed color and stress Residual stress was determined in increments of 5 kg / cm ² from a comparative diagram showing the relationship. The maximum value among the four measured values was defined as the residual stress in the surface layer after nailing. The residual stress in the surface layer after nailing was 55 kg / cm ² .
In the same manner as described above, when the residual stress of the back layer portion after nailing was measured, the residual stress of the back layer portion after nailing was 55 kg / cm ² .

<Evaluation of detergent resistance before nailing>
Next, with respect to another one resin sheet 11 in which four through holes 11H were formed, evaluation of the detergent resistance before nailing was performed.
As shown in FIG. 5, a commercially available spray-type solvent-containing cleaning agent generally used for cleaning the ball game machine was sprayed in the form of foam around each through hole 11H. The cleaning agent was sprayed in a range of about 10 cm diameter around each through hole 11H, and the spraying amount per spot was about 3.0 g.
The following cleaning agents A to D were evaluated using one through hole 11H for each type of cleaning agent.
Cleaning agent A: “Selquick” manufactured by Taihei Shosha Co., Ltd.
Detergent B: “Maxell” manufactured by Kosei Shinsha,
Cleaning agent C: “Serpica” manufactured by Takara Shoji Co., Ltd.
Cleaning agent D: “Refreshing” manufactured by Takara Shoji Co., Ltd.
In FIG. 5, reference signs A to D respectively indicate cleaning agents A to D sprayed in a foam shape.
After leaving the resin sheet 11 sprayed with the cleaning agents A to D at room temperature (20 to 25 ° C.) for 24 hours, the presence or absence of cracks around the through hole 11H is visually observed and before nailing according to the following criteria. The detergent resistance was evaluated.
Judgment standard ○ (good): No crack was seen.
Δ (OK): A relatively small crack of less than 1 mm occurred.
X (impossible): A relatively large crack of 1 mm or more occurred.
For any of the cleaning agents A to D, no crack was observed.

<Evaluation of detergent resistance after nailing>
Next, with respect to another resin sheet 11 in which four through holes 11H were formed, evaluation of the detergent resistance after nailing was performed.
As shown in FIG. 6, for each through hole 11H of the resin sheet 11, using “Autograph AG-2000B” manufactured by Shimadzu Corporation at a speed of 500 mm / min, A 1.85 mmφ diameter, the length of the portion excluding the nail head 26.5 mm, and the length of the screw portion 5.5 mm) were driven by the depth of the sheet thickness. In FIG. 6, reference numeral 13 denotes a nail.
Thereafter, as shown in FIG. 6, the evaluation of the detergent resistance after nailing was performed by the same method as the evaluation of the detergent resistance before nailing. For any of the cleaning agents A to D, no crack was observed.

The evaluation results of Example 1 are shown in Table 3. In Table 3, the unit of residual stress is “kg / cm ² ”.

(Example 2)
In Example 2, a methacrylic resin sheet was obtained in the same manner as in Example 1 except that the production conditions of the extrusion molding step (step (1)) were changed to those shown in Table 2. The obtained methacrylic resin sheet was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

(Examples 3 to 6)
In each of Examples 3 to 6, a methacrylic resin sheet was extruded under the conditions shown in Table 2 in the same manner as in Example 1 (step (1)). Furthermore, in each of these examples, the resin sheet after extrusion molding was cut out to a length of 5 m in the extrusion direction, the sheet cut out by the hot air method was heated under the conditions shown in Table 2, and then placed in an environment of 25 to 30 ° C. It left still and cooled naturally (process (2)). Then, it cut | disconnected in plate shape. The obtained methacrylic resin sheet was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

(Example 7)
As the acrylic rubber (B), “Parapet EB” manufactured by Kuraray Co., Ltd., which is a multilayer structure particle, was used. 30 parts by mass of the multilayer structured particles, 70 parts by mass of methyl methacrylate (MMA), and 0.1 parts by mass of azobisisobutyronitrile were mixed to obtain syrup.
The syrup was degassed and poured into a casting mold. A mold was used in which two glass plates measuring 1000 mm long × 1500 mm wide × 12 mm thick were placed facing each other with a vinyl chloride gasket interposed therebetween.
The mold injected with syrup is immersed in a water bath at 60 ° C. for 4 hours and subjected to primary heating (pre-polymerization), and then secondary heating (post-polymerization) for 2 hours in a hot air oven set at 120 ° C. X A plate-like methacrylic resin sheet having a width of 1500 mm and a thickness of 10 mm was obtained.
The obtained methacrylic resin sheet was evaluated in the same manner as in Example 1. Tables 2 and 3 show the main production conditions and evaluation results.

(Example 8)
In accordance with the method described in Example 1 of Japanese Patent No. 5274840 (Tokuyo No. 2008-523191), a syrup for cast molding containing a block copolymer as an acrylic rubber (B) was obtained.
The syrup was degassed and poured into a casting mold (the same mold as in Example 7). The mold injected with syrup was immersed in a 60 ° C. water bath for 6 hours and subjected to primary heating (pre-polymerization), followed by secondary heating (post-polymerization) for 2 hours in a hot air oven set at 120 ° C. X A plate-like methacrylic resin sheet having a width of 1500 mm and a thickness of 10 mm was obtained. The obtained methacrylic resin sheet was evaluated in the same manner as in Example 1. Tables 2 and 3 show the main production conditions and evaluation results.

(Comparative Example 1)
Using polycarbonate (PC) (“Panlite L-1225Y” manufactured by Teijin Ltd.) as the polycarbonate resin, injection molding was performed under the conditions of a cylinder temperature of 290 ° C. and a mold temperature of 100 ° C. to obtain a polycarbonate resin sheet. Obtained. After injection molding, the polycarbonate resin sheet was cut to prepare four plate-shaped resin sheets having a length of 530 mm, a width of 470 mm, and a thickness of 10 mm. Table 2 shows the main production conditions. Four through holes were formed in each resin sheet by the same method as in Example 1 (see FIG. 2).

<Measurement of residual stress in surface layer and back layer before nailing>
With respect to one resin sheet in which four through holes were formed, the residual stresses of the surface layer portion and the back layer portion before nailing were evaluated.
Since polycarbonate (PC) has a large photoelastic coefficient, the measurement of the residual stress in the surface layer portion and the back layer portion before nailing was performed by the following method different from that in Example 1.
As shown in FIG. 7, a sample was cut out in a cross shape around each through hole from a resin sheet having four through holes (cross width 1 cm, thickness 1 mm).
The cutting direction was parallel to the sheet injection molding direction (longitudinal direction) or the sheet width direction (short direction).
The left figure of FIG. 7 is a partial schematic plan view of one through hole and its vicinity in the resin sheet before cutting out the sample. In the left figure of FIG. 7, a broken line shows a cutting line. The right figure of FIG. 7 is a schematic plan view of the cut sample. In FIG. 7, reference numeral 21 denotes a plate-shaped resin sheet, and reference numeral 21H denotes a through hole. In FIG. 7, reference numeral 22X denotes a cut sample in the width direction of the sheet (two samples in total for one through hole), and reference numeral 22Y denotes a cut sample in the sheet injection molding direction (two in total for one through hole). Sample).
Using one cut sample 22X with respect to one through hole 21H, measurement of the residual stress in the width direction of the surface layer portion and the back layer portion sheet was performed from the side surface. Similarly, using one cut sample 22Y for one through hole 21H, the residual stress in the injection molding direction of the surface layer portion and the back layer portion sheet was measured from the side surface. In the right side of FIG. 7, the measurement direction is schematically shown by a thick arrow.
In the same manner as in Example 1, for each sample 22X and 22Y, the retardation R of the surface layer portion and the back layer portion was measured, and the residual stress of the surface layer portion and the back layer portion was calculated based on the following formula.
Residual stress = R / (55 × T)
(In the above formula, R is retardation, T is sheet thickness (cm), and 55 is the photoelastic constant of polycarbonate ((nm / cm) / (kg / cm ² )).)
The maximum value among the total of 8 measured values obtained as the residual stress of the surface layer portion (a total of 2 cut samples per 4 through holes × 4 through holes) is the residual stress of the surface layer portion of this sheet. did.
Similarly, the maximum value among the total of 8 measured values obtained as residual stress in the back layer portion (total of 2 cut samples × 4 through holes for one through hole) is the back layer of this sheet. It was set as the residual stress of the part.
Table 3 shows the evaluation results of the residual stress before nailing.

<Measurement of residual stress in surface layer and back layer after nailing>
Next, with respect to another resin sheet 21 in which four through holes 21H were formed, the residual stress of the surface layer portion and the back layer portion after nailing was measured by the same method as in Example 1. .
Table 3 shows the evaluation results of the residual stress after nailing.

<Evaluation of detergent resistance before and after nailing>
Next, evaluation of the detergent resistance before nailing was performed using another resin sheet having four through holes formed in the same manner as in Example 1. Further, in the same manner as in Example 1, an evaluation of the detergent resistance after nailing was performed on another resin sheet in which four through holes were formed. The evaluation results are shown in Table 3. Before nailing and after nailing, a relatively large crack of 5 to 40 mm was observed with any cleaning agent.

(Comparative Example 2)
A methacrylic resin sheet was obtained in the same manner as in Example 1 except that the production conditions of the extrusion molding step (step (1)) were changed to those shown in Table 2. The obtained methacrylic resin sheet was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3. In the evaluation of the detergent resistance before and after nailing, no cracks were observed in the cleaning agents A, B, and C, but relatively small cracks of 1 mm or less were observed in the cleaning agent D.

  The present invention is not limited to the above-described embodiments and examples, and can be appropriately modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 110 Extrusion molding means 111 Raw material input part 112 Screw part 113 T die 113A Discharge port 120 Cooling roll unit 121 1st cooling roll 122 2nd cooling roll 123 3rd cooling roll 124 4th cooling roll 130 Protection Film sticking means 131, 132 Protective film roll 140 Take-up means 141, 142 Take-up roll 210 Resin sheet 210M Transparent thermoplastic resin 220 Protective film R1 First manufacturing room R2 Second manufacturing room

Claims (9)

Made of transparent thermoplastic resin,
The thickness is 5-20 mm,
When viewed in the thickness direction, the absolute value of the residual stress in the surface layer portion and the back layer portion is 70 kg / cm ² or less.
Resin sheet for nailing. The transparent thermoplastic resin is a methacrylic resin (A) or a polycarbonate resin,
The nailing resin sheet according to claim 1. The transparent thermoplastic resin is a methacrylic resin (A), and further includes an acrylic rubber (B).
The nailing resin sheet according to claim 1 or 2. The acrylic rubber (B) is a multilayer structure particle including at least one rubber layer.
The nailing resin sheet according to claim 3. Content of the said acrylic rubber (B) is 15-30 mass%,
The nailing resin sheet according to claim 3 or 4. The acrylic rubber (B) contains a block copolymer,
The nailing resin sheet according to claim 3. It is manufactured by extrusion molding or cast molding.
The nailing resin sheet according to any one of claims 1 to 6. Manufactured by an extrusion method,
The resin sheet for nailing according to claim 7. A method for producing a resin sheet for nailing according to any one of claims 1 to 8,
Extruding means for heating and melting the transparent thermoplastic resin and extruding it into a sheet,
A cooling roll unit composed of a plurality of cooling rolls arranged adjacent to each other and cooled while pressurizing the sheet-like material extruded by the extrusion molding means;
Using a manufacturing apparatus provided with a pair of take-up rolls that are arranged to face each other and express the force of taking up the manufactured resin sheet,
Adjusting the overall temperature of the resin sheet within a range of 115 to 165 ° C. at the time of leaving the cooling roll on the most downstream side of the plurality of cooling rolls of the cooling roll unit;
Among the plurality of cooling rolls of the cooling roll unit, when the peripheral speed of the second cooling roll located second from the upstream side is V2, and the peripheral speed of the pair of take-up rolls is VX,
Adjusting the ratio (VX / V2) of the peripheral speed VX of the pair of take-up rolls to the peripheral speed V2 of the second cooling roll within a range of 0.98 to 1.01;
Between the cooling roll unit and the pair of take-up rolls, the resin sheet is gradually cooled by passing through an environment adjusted in a range of 5 to 50 ° C.
Manufacturing method of resin sheet for nailing.

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