JP4077893B2 - Methyl methacrylate resin extruded plate and molded product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a methyl methacrylate resin extruded plate having excellent matting properties. Furthermore, the present invention relates to a methyl methacrylate-based resin extruded plate with little change in matte property on the plate surface even when heat-stretching is performed by secondary processing.
[0002]
[Prior art]
Conventionally, as a technology for imparting matte properties to a methyl methacrylate-based resin extruded plate, the surface of the base resin is provided with irregularities, or an inorganic or organic transparent material that is insoluble in the base resin is dispersed. Have been proposed and are widely used for light diffusion applications such as lighting covers.
In many cases, these light diffusing materials are formed into a desired shape by forming a plate material and then subjecting it to secondary heat stretching.
[0003]
Examples of the secondary heat stretch molding include free blow molding, free vacuum molding, push-up molding, ridge molding, straight molding, drape molding, reverse draw molding, air slip molding, plug assist molding, and plug assist reverse draw molding. Etc.
Although these forming methods involve stretching of the material, as a recent trend, in the lighting cover material, molding including a highly stretched region represented by a corner undercut portion is increasing.
[0004]
[Problems to be solved by the invention]
When these plate materials are subjected to secondary heat stretch molding, the materials are once heated to a temperature higher than the heat distortion temperature to be softened, and shapes such as decompression, pressurization, plug assist, etc. are given alone or in combination. Is generally done. However, when performing these heat moldings, it is very difficult to stretch uniformly, and there is a tendency that the stretching is biased.
[0005]
When this heat stretch molding is performed on a conventional material, the following problems often occur.
When a material having unevenness on the surface of the extruded plate is stretch-molded, the surface unevenness of the highly stretched portion is returned, and the texture of the molded product is uneven.
In addition, when a transparent material insoluble in the base resin is dispersed in the extruded plate, irregularities appear conversely when stretch molding is performed, and this also causes unevenness in the molded product. If a large amount of transparent material insoluble in the base resin is added to prevent this as much as possible, the difference in texture before and after stretch molding will be reduced, but the strength of the molded product itself will be greatly reduced. It was.
[0006]
In view of such circumstances, the present inventor has conducted intensive studies on a methyl methacrylate-based resin extruded plate with excellent matting properties and little change in matting properties of the plate surface even when heat-stretching is performed by secondary processing. By specifying the particle size, content and embossing pattern roughness of the surface of the insoluble resin particles contained in the methyl methacrylate resin extruded plate, matteness (texture) can be achieved even in molded products with different draw ratios depending on the position. ) And the strength of the molded product itself can be maintained, and the present invention has been achieved.
[0007]
[Means for Solving the Problems]
That is, the present invention contains 1 to 6 parts by weight of a crosslinked resin particle having an average particle diameter (Dp) of 10 to 50 μm in 100 parts by weight of a methyl methacrylate resin as a base resin, and a plate thickness of 0.5 to 5 mm. A methyl methacrylate-based resin extruded board having an embossed pattern with a ten-point average roughness (Rz) in the range of 0.2 Dp to 0.5 Dp on at least one side of the resin extruded board It is a board.
Hereinafter, the present invention will be described in detail.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The methyl methacrylate-based resin in the present invention contains 50% by weight or more, preferably 70% by weight or more of a methyl methacrylate unit as its structural unit, and as long as it contains 50% by weight or more of a methyl methacrylate unit. A part thereof may be replaced with a monofunctional unsaturated monomer unit copolymerizable with methyl methacrylate.
[0009]
Examples of the copolymerizable monofunctional unsaturated monomer include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and the like. Methacrylic acid esters, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and the like, Examples thereof include unsaturated acids such as methacrylic acid and acrylic acid, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like.
The copolymer may further contain a glutaric anhydride unit and a glutarimide unit. Further, a blend of diene rubber or acrylic rubber with the aforementioned polymer or copolymer may be used.
[0010]
The resin particles insoluble in the base resin in the present invention are resin particles that do not melt even if extrusion molding is performed, specifically, crosslinked or high molecular weight acrylic resin particles, crosslinked or high molecular weight styrene resin particles, Crosslinked siloxane-based resin particles and the like can be mentioned, but there is no particular limitation as long as the particle size conditions described in the present invention are satisfied.
Among these, crosslinked acrylic resin particles are preferably used.
[0011]
The crosslinked resin particles referred to here are particles having a gel fraction of 10% or more when dissolved in acetone, and the high molecular weight resin particles have a weight average molecular weight (Mw) of 500,000 to 500. It shows 10,000 particles.
[0012]
Acrylic resin particles are monomers containing 50% by weight or more of acrylic monomer units and having one radical-polymerizable double bond in the molecule, and other radical-polymerizable double bonds in the molecule. The particles are polymerized by mixing at least two monomers as necessary.
[0013]
Acrylic monomers are methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, acrylic Examples include ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methacrylic acid, and acrylic acid.
Two or more of these monomers may be used in combination.
[0014]
The monomer having one radical-polymerizable double bond in the molecule is not particularly limited as long as it is other than the above-mentioned acrylic monomer component, and examples thereof include styrene and its monomer. Examples of the styrene derivative include halogenated styrene such as chlorostyrene and bromostyrene, vinyltoluene, and alkyl-substituted styrene such as α-methylstyrene.
Of these, styrene is particularly preferably used.
Two or more of the above monomers may be used in combination.
[0015]
The monomer having at least two double bonds capable of radical polymerization in the molecule is one that is copolymerizable with the above-mentioned monomer and excludes a conjugated diene. For example, 1, 4-butanediol di (meth) acrylate, alkyl di (meth) acrylates such as neopentyl glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetra Alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate; aromatic polyfunctional compounds such as divinylbenzene and diallyl phthalate; And (meth) acrylates of polyhydric alcohols such as trimethylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate.
Two or more of these monomers may be used in combination.
[0016]
Styrenic resin particles are monomers containing 50% by weight or more of styrene monomer units and having one radical-polymerizable double bond in the molecule, and other radical-polymerizable double bonds. It is a particle obtained by polymerizing a monomer having at least two monomers therein if necessary.
[0017]
Styrene monomers are styrene and its monomers. Examples of the styrene derivative include, but are not limited to, halogenated styrene such as chlorostyrene and bromostyrene, alkyl-substituted styrene such as vinyltoluene, and α-methylstyrene.
Two or more kinds of the styrene monomers may be used in combination.
[0018]
The monomer having one double bond capable of radical polymerization in the molecule is not particularly limited as long as it is other than the styrene monomer component described above. For example, methyl methacrylate, ethyl methacrylate, methacrylic acid Methacrylic acid esters such as butyl, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, acrylic Examples thereof include acrylic acid esters such as phenyl acid, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and acrylonitrile.
Among these, alkyl methacrylates such as methyl methacrylate are particularly preferably used.
Two or more of the above monomers may be used in combination.
[0019]
A monomer having at least two radically polymerizable double bonds in the molecule is one that can be copolymerized with the above-mentioned monomer and excludes a conjugated diene, and can be selected from the monomers described above. It ’s fine.
[0020]
Both the styrene resin particles and the acrylic resin particles are polymerized by a method such as a suspension polymerization method or a micro suspension polymerization method to obtain the desired particles.
[0021]
The cross-linked siloxane-based resin is generally called a silicone rubber or a silicone resin, and indicates a solid at room temperature.
Siloxane polymers are mainly produced by hydrolysis and condensation of chlorosilanes. For example, a (crosslinked) siloxane-based polymer can be obtained by condensing chlorosilanes represented by dimethyldichlorosilane, diphenyldichlorosilane, phenylmethyldichlorosilane, methyltrichlorosilane, and phenyltrichlorosilane with hydrolysis.
Moreover, these (crosslinking) siloxane polymer benzoyl peroxide -2, 4-dichlorobenzoyl benzoyl peroxide -p- chlorobenzoyl peroxide Jikyumiru peroxide di -t- butyl, 2,5 -Crosslinking with a peroxide such as dimethyl-2,5-di (t-butylperoxy) hexane, or introducing a silanol group at the terminal of a polysiloxane compound to cause condensation crosslinking with alkoxysilanes. Can be manufactured.
Among these, a crosslinked siloxane polymer in which 2 to 3 organic groups are bonded per silicon atom is preferable.
[0022]
In order to form a crosslinked siloxane-based resin in the form of particles, a method of mechanically pulverizing the crosslinked polymer or a curability containing a specific linear organosiloxane block as described in JP-A-59-68333 A method for obtaining spherical particles by curing a polymer or a curable polymer composition in a spray state, or a specific alkyltrialkoxysilane or a partially hydrolyzed condensate thereof as described in JP-A-60-13813, A method of hydrolyzing and condensing into spherical particles in an aqueous solution of ammonia or amines can be used.
[0023]
The average particle diameter of the insoluble resin particles is 10 to 50 μm. If it is less than 10 μm, even if stretch-molded, it will hardly appear as irregularities, and if it exceeds 50 μm, the mechanical strength of the resin plate will be reduced.
[0024]
The content of the insoluble resin particles in the base resin is 1 to 6 parts by weight. If the amount is less than 1 part by weight, unevenness is hardly generated even if stretch-molded, and if it exceeds 6 parts by weight, the mechanical strength of the resin plate is lowered.
[0025]
The refractive index of the insoluble resin particles of the present invention is not particularly limited, although the absolute value of the difference in refractive index between the base material and the methyl methacrylate resin is about 0 to 0.13. The closer the absolute value of the difference in refractive index from the base resin is to 0, the higher the light transmittance of the resin plate. The refractive index of the resin particles may be appropriately selected depending on the purpose of use of the resin extruded plate (emphasis on permeability and importance on diffusibility).
[0026]
The thickness of the resin extruded plate is most suitable for the combined use of resin particles and an embossed pattern in the range of 0.5 to 5 mm. If the thickness is less than 0.5 mm, the strength is reduced, and if it exceeds 5 mm, the insoluble resin particles hardly protrude on the surface even if stretch molding is performed, and the texture of the molded product is difficult to maintain.
[0027]
As a method for imparting an emboss pattern to the surface of the generally extruded resin plate, a method is adopted in which a soft resin is pressed and transferred to a hard material with irregularities to cure the resin.
This method is a method of manufacturing a resin plate by so-called extrusion molding in which a resin is extruded from a T-die to form a plate and cooled by being sandwiched between rolls. Japanese Patent Publication No. 60-1185, Plastic Material Course [12] Acrylic Resin (Showa) As described in March 25, 45, published by Nikkan Kogyo Shimbun, this is a method using a typed roll, so-called embossing roll.
The embossed pattern in the present invention indicates random unevenness, which is also referred to as mat, satin, or texture. Ten-point average roughness (Rz) is used as an index indicating the roughness of the embossed pattern. This Rz conforms to JIS-B0601.
[0028]
Rz on the surface of the extruded resin plate of the present invention must be in the range of 0.2 Dp to 0.5 Dp in a state where resin particles that are already insoluble in the base resin are already contained. Even if it is less than 0.2 Dp or more than 0.5 Dp, a difference in matte texture between the low stretch portion and the high stretch portion of the molded product appears.
[0029]
In this invention, the roll temperature at the time of transferring the embossing pattern provided to the embossing roll to a resin extrusion board is not specifically limited. In the prior art, for example, Japanese Examined Patent Publication No. 60-1185, it is described that the surface temperature of the shibo roll needs to be close to or higher than the heating temperature at the time of heat forming the sheet. Even if it is transferred at a roll temperature lower than the heating temperature at the time of thermoforming, insoluble resin particles get into the recesses of the embossing roll and solidify by cooling while forming irregularities, so even if secondary molding at high temperature, matte The change in texture is reduced.
[0030]
In order to include resin particles in a methyl methacrylate resin to form an extruded plate, a known mixing / molding method can be used.
One is a method in which each component is melt-kneaded and then formed into an extruded plate. The composition is obtained by using a kneading apparatus such as a commonly used single-screw or twin-screw extruder or various kneaders, and further. After melt-kneading with a single-screw or twin-screw extruder or the like, it is processed into a plate shape via a T die and an emboss roll unit.
It is also possible to obtain an extruded plate directly by omitting the above-described melt-kneading step.
[0031]
Further, the extruded plate of the present invention has an inorganic barium sulfate, calcium carbonate, glass, clay, talc, mica, titanium oxide, aluminum hydroxide, alumina, zinc oxide as an internal light diffusing agent, and an organic crosslinked styrene resin. There is no problem even if particles, crosslinked siloxane-based resin particles, and the like are included, but it is desirable in terms of maintaining mechanical strength that the average particle diameter is less than 10 μm and the content in the plate is suppressed to 3 parts by weight or less.
In addition, there is no particular problem even if known additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a release agent, a flame retardant, and an antistatic agent are dispersed.
[0032]
【The invention's effect】
Even if the methyl methacrylate resin extruded plate of the present invention is subjected to secondary heating stretch molding in which the stretch ratio is different within the same molded product, the difference in matte texture on the surface of the molded product can be reduced.
Accordingly, the methyl methacrylate-based resin extruded plate is suitably used for applications involving secondary molding with relatively complicated and uneven stretch ratios such as lighting covers.
[0033]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not restrict | limited at all by these Examples.
The evaluation method is as follows.
(1) Average particle diameter optical diffraction scattering particle size measuring apparatus (Nikkiso Co., Ltd., Microtrac particle size analyzer Model 9220 FRA) measured by and the average particle size values of D _50.
(2) The side of the molded product obtained by impact-resistant push-up molding is cut out at 7 cm × 7 cm, the periphery is supported, a steel ball weighing 200 g is dropped at the center, and the cracked height (cm) Was made impact resistant.
(3) Surface roughness (Rz)
Ten-point average roughness (Rz) was measured with a surface roughness shape measuring instrument (Surfcom 550A manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS-B0601.
(4) Visual evaluation The side of the molded molded product that had been stretched was compared with the unstretched portion, where the change in the matte state on the surface was small, and the change was marked as x.
[0034]
The equipment used is as follows.
・ Extruder: Screw diameter 40mm, uniaxial, manufactured by Tanabe Plastics Co., Ltd. ・ T die: Width 220mm, Lip distance 4mm
Roll unit: diameter 200 mm, width 300 mm, set of 3 vertical, upper and lower stages are polishing rolls, middle stage is embossing roll, a roll (Rz = 5 μm), b roll (Rz = 17 μm) depending on the surface roughness ), C roll (Rz = 50 μm), and d roll (polishing roll).
[0035]
Reference example Cross-linked methacrylic resin beads (Sumipex XC-1A, manufactured by Sumitomo Chemical Co., Ltd., refractive index 1.49, average particle size 35 μm: particle A) wind classifier (TC-15N manufactured by Nissin Engineering Co., Ltd.) And classified into particles B having an average particle diameter of 25 μm, particles C having an average particle diameter of 47 μm, and particles D having an average particle diameter of 71 μm.
[0036]
Examples 1-6, Comparative Examples 1-6
100 parts by weight of methacrylic resin beads (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd., refractive index 1.49) and the amount of crosslinked particles prepared in Reference Example shown in Table 1, calcium carbonate particles (Sipron A, Cypro Kasei Co., Ltd.) After mixing 2 parts by weight with an average particle diameter of 8 μm and a refractive index of 1.51) with a Henschel mixer, an extruded plate having a resin temperature of 265 ° C. and a thickness of 2 to 4 mm is passed through an extruder, a T-die, and a roll unit. Was made.
Next, a 30 cm × 20 cm extruded plate was heated to a surface temperature of 180 ° C. with a far-red panel heater from both sides, and a push-up molding machine (TF-300 type manufactured by Osaka Sheet Machine Co., Ltd., push-up area 10 cm × 5 cm, bump Using a raised height of 10 cm, a molded product having a matte property was obtained.
The evaluation results are shown in Table 1.
[0037]
Example 7
To 100 parts by weight of the same methacrylic resin beads as in Example 1, 5 parts by weight of crosslinked siloxane-based resin particles (Tospearl 3120, manufactured by Toshiba Silicone Co., Ltd., average particle diameter 12 μm, refractive index 1.43) were mixed with a Henschel mixer. An extruded plate having a resin temperature of 265 ° C., a thickness of 2 mm, and a width of 20 cm was produced from the material through an extruder, a T die, and a roll unit.
Further, a molded product having a matte property was obtained in the same manner as in Example 1.
The evaluation results are shown in Table 1.
[0038]
[Table 1]

Claims (2)

A resin extruded plate containing 1 to 6 parts by weight of crosslinked resin particles having an average particle diameter (Dp) of 10 to 50 μm and 100 parts by weight of a methyl methacrylate resin as a base resin and having a thickness of 0.5 to 5 mm A methyl methacrylate resin extruded plate having an embossed pattern having a ten-point average roughness (Rz) in the range of 0.2 Dp to 0.5 Dp on at least one surface of the resin extruded plate.   A molded article having matte properties obtained by subjecting the methyl methacrylate-based resin extruded plate according to claim 1 to heat stretch molding.