CN1993410B

CN1993410B - Foamed sheet, and method and apparatus for producing same

Info

Publication number: CN1993410B
Application number: CN2005800258633A
Authority: CN
Inventors: 西林利弥
Original assignee: DUELLER CORP
Current assignee: DUELLER CORP
Priority date: 2004-07-30
Filing date: 2005-07-27
Publication date: 2012-05-30
Anticipated expiration: 2025-07-27
Also published as: TWI347334B; WO2006011521A1; JP4093419B2; TW200615317A; KR100842524B1; CN1993410A; JP2006045259A; KR20070039106A

Abstract

Disclosed is an unstretched foamed sheet containing a thermoplastic resin. Not less than 80% of air bubbles contained in the sheet has a diameter of 0.1-20 mum, and the porosity of the foamed sheet is 20-80%. Also disclosed are a method for producing such a foamed sheet and an apparatus suitable for producing such a foamed sheet. Further disclosed are a light-reflecting plate using such a foamed sheet and a display.

Description

Foaming plate, its method of manufacture and manufacturing installation

Technical field

The present invention relates to the plate that foams.Say in detail to be exactly to the present invention relates to separator materials such as light reflecting board, battery, packing material, steel plate lamination with material etc.; The foaming plate that particularly can appropriately use with light reflecting board with the flat light source that uses in the backlight mechanism, be adapted at the device that uses in its method of manufacture and its manufacturing installation and light reflecting board and the display unit of using this foaming plate as display unit such as liquid crystal.

Background technology

In recent years as the display equipment of the indicating meter of notebook computer or desktop computer, TV, portable phone etc., mostly use can slimming display unit such as liquid crystal.For example liquid crystal indicator is not owing to himself being twinkler, so be just can show from the rear side irradiates light through the flat light source that is called backlight is set.This backlight normally takes to be called the flat light source structure of side lamp type or full run-down type for the uniform irradiation whole image.Particularly because notebook computer etc. is hoped slim, miniaturized, so in the possible purposes of slim liquid-crystal display, side lamp type (being the form of irradiates light from the side for picture promptly) backlight is suitable for (with reference to patent documentation 1,2) usually.On the other hand, in the so big picture of LCD TV is used, because the side lamp mode can not reach high brightnessization, so be to adopt full run-down type lamp mode.

Usually under the situation of side lamp mode; Cold cathode ray tube as light source; Make light in the inner face of light guiding plate, evenly propagate, spread from the light guiding plate edge; And for handle reflects to the liquid crystal panel direction to the light with the diffusion of liquid crystal panel reverse direction from light guiding plate expeditiously, so below light guiding plate, be provided with reflector.And full run-down type lamp mode is to be set up in parallel cold cathode ray tube in the bottom of liquid crystal panel, cold cathode ray tube abreast and be listed on the reflector.As reflector can use plane or cold cathode ray tube partially-formed as the semicircle concavity etc.

As stated, for the whole image of uniform irradiation liquid crystal indicator, the reflector role is big.Just require high reflection characteristic for the reflector that satisfies this effect, existing is to use inside thin slice that contains micro bubble and the thin slice that has added white pigment etc. separately, or these sheet adherings in metal sheet, the first-class use of plastic plate.As the thin slice that this reflector uses, be to use the two spool extension white polyester sheet smaller mostly to reflected light directive property.Extending white polyester sheet in length and breadth is absorb fillers in resin, extends after being shaped through plate and forms fine voids.

But the existing main application of LCD device is a notebook computer, but adds in recent years in the various machines such as display equipment of desktop computer and TV, mobile phone etc. and be used and expansion to some extent.Just seeking to obtain brighter distinct image, be used to realize that the improvement of high brightness, high degree of accuracy liquid crystal panel makes progress, also stricter for the desired characteristic of reflector.Therefore, be used for improving the discussion of extending the white polyester sheet reflection characteristic and carrying out (with reference to patent documentation 2,3) with keen determination.

But when the extension white polyester sheet is wanted to increase number of bubbles in order to improve reflection characteristic, just need in polyester, increase the use level of the resin and the particle of non-conforming.Therefore, this non-conforming resin and particle become the reason that reduces reflection characteristic on the contrary as light absorbing impurity, therefore, are difficult to hope to improve reflection characteristic.And,, consequently produce unfavorable phenomenons such as luminous reflectance factor reduction sometimes to specific wavelength so the general size of bubble is even owing to be through extending to form bubble.And under the situation of full run-down type lamp mode backlight, need carry out the shaping processing of waveform, but because the residual extensibility of the white polyester sheet that is extended is little, so be not suitable for this shaping processing to reflector.

As the substitute of above-mentioned extension white polyester sheet, that knows has: remain on roller in the pressurized inert gas, after rare gas element being contained be dipped in the vibrin plate, heating makes foaming and the polyester resin foamed plate (with reference to patent documentation 4) that obtains under normal pressure.[title with MCPET (login trade mark) can obtain from The Furakawa Electric Co., Ltd.].

The polyester resin foamed plate that obtains through this method is owing to be the mechanism that produces bubble when utilizing the pressure that discharges rare gas element, so contain impurity or bubble size is in full accord unlike the foaming that kind that is obtained by extension.Consequently with extend white polyester sheet mutually specific energy improve reflection characteristic.And owing to be not to extend thin slice, the processing that is shaped is also easy.

Like this, above-mentioned polyester resin foamed plate has just been filled up the shortcoming of extending white polyester sheet.But owing to just need expend time in, so productivity is bad in order to contain rare gas element to be dipped in the vibrin plate.And because the plate surface is easy to generate brokenly bubble, so shaggy shortcoming is arranged.If further non-foam layer is set, then only after making the foaming of vibrin plate,, the shortcoming of bringing bad influence to reflection characteristic is arranged also then there not being the method that the foaming plate is pasted on the surface.

Know TEB 3K to be that polymer and whipping agent melt to mix through forcing machine and obtain foam cylindraceous in addition, then through extend, cooling, and cut and be distracted into tabular and method of manufacture (with reference to the patent documentation 5) plate that obtains foaming.And know and extrude the micro bubble polymer materials of plate form and the method (with reference to patent documentation 6) of form layers compound article.But these methods so bubble size is big, can not fully improve reflection characteristic owing to can not control the size of bubble.

In the patent documentation 6 disclosed methods, the foaming plate is to set to close through the bonding layer that carries out with the laminate that does not have the foaming plate.But the bonding layer that is laminated in closes the border is arranged at the interface, thus producing reflection, refraction at the interface, even the absorption that also produces light, consider to have and bring the unfavorable condition of bad influence for easily whole reflection characteristic.

Also know the method (with reference to patent documentation 7～9) that in forcing machine, makes gas the resin combination effect obtained porous matter and even lathering property thin slice and plate is arranged.But in the patent documentation 7 disclosed methods, even suppress low to the inert gas concentration in the polymkeric substance, bubble is not only big, nor can in the light reflecting board of micro bubble, use.In the patent documentation 8 disclosed methods, in case also be to emit gas after forming plate, then the two sides gas concentration of plate has deviation, and the foaming part produces inhomogeneous with the partially mixed existence that does not have too foaming.Even in patent documentation 9 disclosed methods, considering has the unfavorable condition that bubble size becomes to grow up when extending.

Like this, although the control of size or the shape of bubble is not only extremely important in the foaming plate, and be difficult.

Patent documentation 1: the spy of Japan opens clear 63-62104 communique

Patent documentation 2: the spy of Japan opens the 2003-160682 communique

Patent documentation 3: the spy of Japan opens the 2001-305313 communique

Patent documentation 4: Japan speciallys permit communique No. 2713556

Patent documentation 5: the spy of Japan opens the 2000-86795 communique

Patent documentation 6: the special table 2001-510749 of Japan communique

Patent documentation 7: the spy of Japan opens the 2002-338726 communique

Patent documentation 8: the spy of Japan opens the 2000-119432 communique

Patent documentation 9: Japan speciallys permit communique No. 2902242

Therefore; Just have and develop following problem, that is, and the above-mentioned existing boundary of white polyester sheet reflection characteristic and the difficulty of the processing that is shaped of extending in length and breadth; And then appropriately change the size of bubble, shape according to purposes; Productivity is good, the surface beautiful, as light reflecting board with suitable fine foaming plate.

Summary of the invention

Above-mentioned problem solves through the present invention of following record.

That is, the present invention contains thermoplastic resin and the nothing that constitutes is extended the foaming plate, have the bubble footpath of 0.1～20 mu m range in the bubble that relates in the plate being comprised more than 80%, and voidage is 20～80% foaming plate.

Other forms of the present invention relate to foam method of manufacture of plate, it comprises: the melt polymer of the thermoplastic resin that has dissolved gas under acomia blister attitude, form plate operation, make the operation that produces bubble in a vacuum through under 50～200 ℃ temperature condition, exposing plate.

Other forms again of the present invention relate to foam method of manufacture of plate, its thermoplastic resin that has dissolved gas with do not have the thermoplastic resin of gas dissolved to extrude together.

Extrusion device is used in other forms again of the present invention relate to foam manufacturing of plate; It is the forcing machine that possesses screw rod, cylinder barrel and cylinder barrel thermoregulation mechanism; At a part of inner face of this cylinder barrel, possess and be used for from being arranged on the nozzle that the outside high pressure gas feed unit gas supplied of this cylinder barrel imports.

Other forms again of the present invention relate to the foaming plate and use manufacturing installation, dispose: vacuum chamber device, and it possesses the chamber and the sealing mechanism that can reduce pressure inside at the casting roller of sheet forming machine and/or after casting roller; Vacuum generating device, it is attached to this vacuum chamber device.

Description of drawings

Fig. 1 is the diagrammatic illustration figure of expression the present invention embodiment plate with manufacturing installation;

Fig. 2 is the diagrammatic illustration figure in expression the present invention embodiment extrusion device nozzle segment longitudinal section;

Fig. 3 is that expression is the diagrammatic illustration figure in extrusion device nozzle segment shown in Figure 2 transverse section of cut-out in the A position.

Nomenclature

1 extrusion device 11a extrusion device, 22 infeed means

3 molds, 4 casting rollers, 5 take off roll 1

5a take off roll 26 Vakuumkammers 7 vacuum pumps

The cylinder body of 8 plates, 11 cylinder body 11a nozzle segments

12 screw rods, 13 well heaters, 14 jet elements

14a nozzle medium

14b ventilating pit 15 gas inlets

Embodiment

The result that the present inventor discusses has with keen determination found following content: the micro bubble that when not having the extension cast panel, also has 0.1～20 mu m range; And the voidage of representing the gas phase occupation rate for certain above bubble density is in 20～80% scope, then as the foaming plate that should in light reflecting board etc., use can obtain that the unexistent surface of said existing foaming plate is beautiful, easy shaping processability and good productivity.

Foaming plate of the present invention is owing to be do not have to extend the foaming plate, so according to the purposes that is suitable for the foaming plate and the processing that is shaped easily.Extend in this said nothing and to be meant and not carry out, follow casting or form plate and the extension that produces degree and admit of so that plate produces single shaft or two extensions that are oriented to purpose and carry out.

Owing to foaming plate of the present invention, has the bubble footpath of 0.1～20 mu m range in the bubble that is comprised in the plate more than 80%, so can obtain good reflection characteristic.The bubble footpath that has 0.4 μ m～8 mu m ranges in the bubble that is preferably comprised in the plate more than 80%.Because the bubble footpath can cause interference of light effect etc. when too small, so can not obtain enough reflections.When excessive as if the bubble footpath on the contrary, then need become the thickness of plate greatly owing to have a certain amount of interface number, consequently the physical strength of plate dies down, and needs than hopes the thick design of film thickness etc., and it is practical to be difficult to supply.

In the existing extension board because bubble footpath evenly; So the unfavorable condition of the luminous reflectance factor reduction etc. of pair specific wavelength is arranged; But the bubble that foaming plate of the present invention is in the plate and is comprised is directly expressed proper distribution, and can obtain good reflection characteristic, and is favourable in this.

Foaming plate of the present invention is because voidage is in the scope that is 20～80%, so can obtain good reflection characteristic.Voidage is suitable with foaming bubble density that plate contained, expression be the gas phase occupation rate of plate, can ask it according to plate and the density of the resin that uses and the volume of plate.Preferably the voidage of plate is 50～70%.This is owing to be spherical shape in order to keep bubble shape, and theoretic maximum interspace rate is about 70%, if too surpass it, then bubble is destroyed and can not obtains the cause of good reflection characteristic.On the contrary, if voidage is low excessively, then the density of bubble is just low excessively, the reflection characteristic that can not obtain hoping.

When using the reflector that uses in the backlight unit of foaming plate as full run-down type lamp mode, usually the foaming plate is applied the processing that is shaped with the forming temperature more than 100 ℃.Because this shaping handling ease and show good reflection characteristic, be more than 100% so foaming plate of the present invention is preferably in the extension elongation at failure that 100 ℃ environment measures down, and the extension stress under 100 ℃, 100% elongation is below the 50Mpa.Extending elongation at failure is to be ideal more than 150%, and extending stress is the ideal below 0～30Mpa.

The main thermoplastic resin that formation the present invention foams plate in order to promote fine foaming, then preferably melts the high resin of tension force.Therefore, represent that preferably the mobile melt flow dose rate (being as the criterion with ASTM D 1238-98) of melted state is 0.5～44g/10 minute a thermoplastic resin, the flowability of melted state is that 1.4～30g/10 minute thermoplastic resin is better.The flowing property of thermoplastic resin is as the criterion and decides with the measuring condition of putting down in writing among the ASTM D1238-98 about various polymkeric substance (temperature, load).

Object lesson as the thermoplastic resin that can use in the present invention; Can enumerate; For example; Vinyl resin, methacrylic resin, polyolefine, polymeric amide, polyester, polycarbonate, styrene resin, polyethers, urethane, polyphenylene sulfide, polyesteramide, polyether ester, SE, Noryl, polyarylester, polysulfones, polyimide, polyetherimide, polyamidoimide, be the multipolymer of staple and their mixture etc., but be not limited to these with them.

Particularly; Owing to use vinyl resin and/or methacrylic resin when constituting the main thermoplastic resin of foaming sheet of the present invention; Can obtain good especially fine lathering property, formability, thus preferred, in addition; Because the transparency of resin itself is high, therefore final reflection at the bubble interface also becomes good.In addition, photostabilization is also excellent, and material resin can also obtain less expensively.

As the such vinyl resin or the object lesson of methacrylic resin; Can enumerate; For example; The homopolymer of propenoate or methacrylic ester, or the multipolymer of the above propenoate of 50 weight % or methacrylic ester and other more than one vinyl monomers; Wherein, The multipolymer of the methacrylic ester that preferred 50 weight % are above and more than one other vinyl monomers, the alkyl methacrylate that especially preferred 50 weight % are above and below alkyl acrylate below the 50 weight % and the 49 weight % can with the multipolymer of more than one vinyl monomers of at least one copolymerization of alkyl methacrylate and alkyl acrylate.The preferred 0.1 weight % of the alkyl acrylate that contains in the multipolymer～40 weight % is more preferably 1 weight %～15 weight %.Aforesaid propylene acid resin or methacrylic resin can be distinguished independent use, also can mix use.

As such propenoate; Can enumerate; For example, methyl acrylate, ethyl propenoate, Bing Xisuandingzhi, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-EHA, vinylformic acid 2-hydroxy methacrylate etc., preferred especially methyl acrylate, ethyl propenoate.In addition; As methacrylic ester; Can enumerate; For example, TEB 3K, Jia Jibingxisuanyizhi, NSC 20956, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methylacrylic acid 2-ethylhexyl, 2-hydroxyethyl methacrylate etc., special preferable methyl methyl acrylate, Jia Jibingxisuanyizhi.As other vinyl monomers that can copolymerization; Except above-mentioned propenoate or the methacrylic ester; Can also enumerate; For example, unsaturated acids such as vinylformic acid, methylacrylic acid, vinylbenzene, alpha-methyl styrene, vinyl cyanide, methacrylonitrile, maleic anhydride, phenyl maleimide, cyclohexyl maleimide etc.

The weight average molecular weight of aforesaid propylene acid resin or methacrylic resin (Mw) preferably 40,000～400,000, better is 60,000～300,000.If Mw is too small, and the physical strength of the foaming plate that then obtains is insufficient sometimes, and if Mw is excessive, and then melt viscosity uprises, and extrusion performance reduces sometimes.

Above-mentioned vinyl resin or methacrylic resin also can contain the rubber-like polymer.Through cooperating the rubber-like polymer to vinyl resin or methacrylic resin, can improve the viscosity and the toughness of resin, so can obtain the good foaming plate of shock-resistance.

Also can be in the scope of not damaging foaming plate reflection characteristic to thermoplastic resin of the present invention with a spot of; Various additives below preferably 0～3% weight range cooperates, i.e. crystal nuclear agent, crystal promotor, the agent of bubble nuclear, inhibitor, stablizer, processing aids, plasticizer, charged preventor, shock-resistant auxiliary, whipping agent, weighting agent, matting agent, parting agent, fire retardant, UV light absorber, ultraviolet ray prevent agent, pigment, dyestuff, lubricant, white dyes etc.

Wherein as the agent of bubble nuclear and acting inorganic fine particles; Preferably can form the hole as nuclear, for example can use: lime carbonate, magnesiumcarbonate, zinc carbonate, titanium oxide (Detitanium-ore-type, rutile-type), zinc oxide, permanent white, zinc sulphide, alkaline carbonic acid tin, mica titanium, weisspiessglanz, Natural manganese dioxide, calcium phosphate, silicon-dioxide, aluminum oxide, mica, talcum, kaolin etc. with himself.Wherein it is desirable to use visible region to absorb few lime carbonate, permanent white especially to 400～700nm.If there is absorption the visible region, then produce the problem that brightness reduces sometimes.

In order in plate, to form bubble, for example can enumerate carbonic acid gas, nitrogen, butane, helium, argon etc. as the gas that in forcing machine, is dissolved in the thermoplastic resin.Wherein carbonic acid gas, nitrogen low at gas permeation rate, cheap and can the point of safe handling on for well, also can be used alone or in combination them.

Foaming plate of the present invention is set the reflectivity of visible-range more than 85% for, is set in total light transmittance below 10%, and this is beautiful as the surface, and the foaming plate that particularly suitable light reflecting board is used is an ideal.

Foaming plate of the present invention also can duplicate the embossing decorative pattern at least on single face.This embossing processing can be carried out through following method; Promptly through on the casting roller that is formed with fine decorative pattern from the teeth outwards decorative pattern after method that the thermoplastic resin plate duplicates or the casting roller through no decorative pattern are wound up into the foaming plate that has formed plate on the roller quickly, be re-applied to the method for duplicating decorative pattern to plate on the calender device that the surface has fine decorative pattern.Can enumerate as fine decorative pattern and to be used to carry out wrinkle pattern, grid pattern, hemispherical pattern, chevron pattern, the pyramid shape pattern that the high-level efficiency luminous reflectance is used, or their Compound riffled etc.

Foam thickness 20～500 μ m preferably of plate of the present invention, 35～350 μ m are then better.Thickness then is difficult to guarantee the flatness of plate as if too small, is easy to generate bright inhomogeneous when using as light reflecting board.If thickness is excessive on the other hand, and then plasticity is bad sometimes.

Said foaming plate of the present invention, also can dispose one deck to it at least according to application target becomes two-layer above laminated wood.Set for when being laminated wood, preferably 1/200～1/3,1/50～1/4 better for the ratio of its secondary layer portion/main stor(e)y portion.Portion/main stor(e)y portion/when pair layer portion was three-layered lamination plate or the laminated wood more than three layers, this ratio was represented with the total/main stor(e)y portion of two secondary layer portion at secondary layer.Except above-mentioned foaming plate, also can dispose one deck non-foam layer at least in the laminated wood.Foaming plate of the present invention preferably is configured in the laminated wood as above-mentioned main stor(e)y portion.

Laminated wood of the present invention also can be through coextrusion, extrude range upon range of, heat lamination, coating, vapor deposition waits and forms.Particularly the laminated wood of coextrusion is best.This laminated wood for example can through from foaming layer with main extruder and non-foam layer with the polymkeric substance of secondary forcing machine in mold mouth mould manifold portion or be arranged on the entering mould before feeding portion converge formation.This coextrusion laminated wood is not owing to need be provided with bond layer, so favourable for reflection characteristic, productivity is also good simultaneously.Better is for example can make in the foaming part and not have foaming through setting for the main raw material of main extruding layer and secondary extruding layer composition identical partly not have border etc. in the place; Can reduce the influence of main stor(e)y and secondary layer boundary surface, can be favourable when particularly using as light reflecting board.

This coextrusion laminated wood can not only be the double-layer structure of main stor(e)y (A layer) and secondary layer (B layer); And can also be the three-decker of (B layer) (A layer) (B layer); And then can be to have (B layer) (A layer) (B layer) (A layer) ... The multilayered structure of (B layer) (A layer) (B layer), very effective on the point of the easy control thickness direction bubble formation state of ability.

Extrusion device is used in other forms of the present invention relate to foam manufacturing of plate; It is the forcing machine that possesses screw rod, cylinder barrel and cylinder barrel thermoregulation mechanism; At a part of inner face of this cylinder barrel, possess and be used for from being arranged on the nozzle that the outside high pressure gas feed unit gas supplied of this cylinder barrel imports.This extrusion device is fit to the manufacturing of above-mentioned foaming plate of the present invention or laminated wood.At this, said high pressure is the pressure of postcritical state preferably, for example be to the situation of extruding the favourable carbonic anhydride of gas foaming under, stagnation point is 31.3 ℃ of temperature, 7.52Mpa firmly.Therefore, the high pressure gas feed unit preferably can be all gases to surpass the device that the state of stagnation point is separately supplied with.

The employable extrusion device of the present invention also can be any of series connection forcing machine of series connection forcing machine, combination biaxial extruder and the single shaft forcing machine of single shaft forcing machine, biaxial extruder, binding single shaft forcing machine.The cylinder barrel of forcing machine partly possesses: the well heater that is used to heat, comprise the register that is used for refrigerative air cooling device, water cooling plant or oil cooling device, they preferably can be divided into 5～10 sections and control.Cylinder barrel preferably can be distinguished with the temperature adjustment control section and by sectionization identically.Screw rod mainly is divided into district, the district of fusing press resin, the compression district of mixing of feeding material resin usually.The size of screw rod etc. can be carried out optimum design according to employed resin.

The set inside of said extrusion device is useful on and in forcing machine, makes the nozzle of gas dissolving in the resin that has melted, and preferably is configured in the fusing compression zone of screw size.Be exactly specifically, this nozzle is set in place on the inner face of the cylinder barrel one section part of fusing compression zone, is used for importing from being arranged on outside high pressure gas feed unit gas supplied.

Its shape of nozzle preferably spreads all over the minute aperture in full week on the inner face of cylinder barrel one section part; For example be to have following, the structure of voidage below 25% of bubble footpath 30 μ m; Be exactly that the nozzle that can load and unload the ring-type of metal or pottery formation is installed on the cylinder barrel inner face specifically.This annular metal preferably is made up of the material of sintering metal powder or steel fiber.

Other forms again of the present invention relate to the foaming plate and use manufacturing installation, dispose: vacuum chamber device, and it possesses the chamber and the sealing mechanism that can reduce pressure inside at the casting roller of sheet forming machine and/or after casting roller; Vacuum generating device, it is attached to this vacuum chamber device.This manufacturing installation is fit to the manufacturing of above-mentioned foaming plate of the present invention or laminated wood.

The foaming plate of this vacuum chamber device in order to obtain hoping preferably can reduce pressure the chamber interior that can reduce pressure to below the 30Mpa.

The employable sheet forming machine of the present invention generally includes: be used for molten resin forcing machine, be used to form plate flat-die, be used for the casting roller of cooling plate, the towing mechanism and the wind2 of plate.Flat-die is T shape mould preferably, can enumerate: possess range upon range of infeed mean device in the branch manifold type of mould inner laminated with in front of mould.The casting roller possesses temperature adjustment function usually, and method for regulating temperature makes water coolant, warm water or wet goods carry out round-robin, also has further to make up with induction heating mode.The plate towing mechanism also can then be cast the temperature adjustment function that roller has roller, also can possess: apparatus for measuring thickness, shortcoming proofing unit, prevent surface processing devices such as Charging system, corona treatment and framework processing.Wind2 also can possess: swiveling head mechanism, touch roll mechanism, change of lap mechanism, tenslator etc.

The employable chamber device of the present invention is to be positioned at casting roller or the top that then casts the towing mechanism central roll of roller, has along the section of the curvature of roller, and meets the case shape device of plate width, can discharge the air of chamber interior through the vacuum pump of outer setting and reduce pressure.Chamber has the sealing mechanism that is used to keep vacuum, is made up of a plurality of spaces as required.

The sealing mechanism of the employable subsidiary chamber device of the present invention comprises: for the moving direction of plate current be inlet seal, the outlet of inlet side exit seal, be configured in the side seal of both sides, can adopt labyrinth seal type, contact roller mode closed type etc. for inlet seal and exit seal.Can adopt labyrinth seal type, contact guidance type etc. as side seal.

About the foam method of manufacture of plate of the present invention, at its concrete example of following explanation, but the present invention is not limited to these concrete examples.

At first as required the moldable resin sheet that becomes heating and/or dry raw material heat, respectively to preheated can foam main extruder of extruding (A) and the secondary forcing machine (B) that foams supply.Main extruder (A) is through being positioned at the outer gas supply device of machine preferably with the condition supply gas more than the super critical condition.In main extruder (A) inside, the thermoplastic resin and the gas that have melted are fully mixed, and make gas dissolving in thermoplastic resin and be extruded.

The polymkeric substance of extruding the polymkeric substance of extruding from main extruder (A) (a) with from secondary forcing machine (B) (b) merges into (b) (a) after (b) three layers through infeed mean, supplies with to T shape mould, and becomes tabular and spue.At this moment adjust gas delivery volume so that polymkeric substance (a) becomes and is dissolved with gas and is the nothing foaming board status that does not have foaming.

The plate land that spue from T shape mould are cooled off at the casting roller.At this moment the plate uniform plate of vitreous state normally.After the temperature that is cooled to stipulate on the casting roller, import plate to the take off roll of then casting roller.Be exposed to plate under the vacuum state through the Vakuumkammer that is arranged on the take off roll then.Like this, plate is varied to the plate of ultrawhite look with regard to producing fine foaming.Afterwards through up-coiler this coiled sheet on roller.

Said foaming plate of the present invention or laminated wood can be made through comprising the method for extruding the operation that makes foaming to the thermoplastic resin that has dissolved gas.At this moment, also can not use vacuum chamber device to foam, also can make the plate of acomia blister attitude or foamed state pass through vacuum chamber device.

Certain form of the present invention relate to foam method of manufacture of plate, it comprises: the melt polymer of the thermoplastic resin that has dissolved gas under acomia blister attitude, form plate operation, make the operation that produces bubble in a vacuum through under 50～200 ℃ temperature condition, exposing plate.This method of manufacture is fit to the manufacturing of above-mentioned foaming plate of the present invention or laminated wood, and above-mentioned each operation is successive preferably.At this, temperature condition it would be desirable 70～120 ℃.

" forming plate with acomia blister attitude " among the present invention, is to make gas dissolving in the molten resin polymkeric substance, and when partly being spued by mold, forms plate with acomia blister attitude, can carry out through the amount and/or the control condition of spuing that reduce gas dissolved.The plate of blister attitude that this is acomia is owing to having gas dissolving in the polymkeric substance, so through just making foaming easily to stimulations such as plate reduce pressure.

Form the foaming method behind plate according to this, the condition of temperature through the adjustment plate or decompression etc. just can be controlled the generation state of bubble easily, therefore, makes optimized some coideal of bubble size and number of bubbles easily.

The foaming plate is to have dissolved the thermoplastic resin of gas and do not had the thermoplastic resin of gas dissolved to extrude the manufacturing gained together through handle in certain form of the present invention.This method of manufacture is fit to the manufacturing of above-mentioned foaming plate of the present invention or laminated wood.

Like this, foaming plate of the present invention can obtain through using then gas to supply with formation panel assembly and the vacuum chamber device extruded.Therefore, can productivity on flow line make reflection characteristic, processibility, plate that surface smoothing property is good well.

Said foaming plate of the present invention or laminated wood can use as light reflecting board rightly.This light reflecting board also can have been implemented the processing that is shaped to said foaming plate or laminated wood.

Shaping processing of the present invention is meant the mould of use ability attemperation, through carrying out vacuum forming, pressing empty shaping or drawing or rolling press processing etc. to obtain molding.

Embodiment

Followingly specify the present invention, but the present invention is not limited to this embodiment according to embodiment.

[evaluation method]

1, reflectivity

Reflectivity is to go up to continue to get the state of φ 60 integrating sphere 130-0632 [(strain) Hitachi system] and 10 ℃ of inclination liners at spectrophotometer U-3410 [(strain) Hitachi system]; For the two sides of foaming plate or laminated wood obtain visible-range (380～780nm) reflectivity, high value as reflectivity.

2, voidage

Voidage is the ratio of the relative resin board volume of bubble volume, is the volume of obtaining sample according to the thickness and the area of plate, and gravimetry uses following formula as voidage.

Voidage (%)=[1-(weight/resin density)/volume] * 100

3, plate thickness

Thickness measurement about foaming plate or laminated wood; Be on the width of foaming plate or laminated wood, 10 measuring points to be set equally spaced; After used thickness meter (teclock society system thickness gauge) has been measured the thickness of measuring point, the average thickness of each point measured value as the foaming plate.

4, total light transmittance

Total light transmittance is as the criterion with JIS K7150:1981 and estimates foaming plate or laminated wood.

5, extend elongation at failure

Extend elongation at failure and be to use (strain) Ou Lienteke (オリエ Application テ Star Network) system day western sieve (テ Application シロ Application) UCT-100 elongation test machine; The plate of width 10mm, length 100mm after keeping 5 minutes under 100 ℃ the environment; When making elongation with 300mm/ minute, the MV of elongation at failure on plate length direction and the transverse direction.

6, extend stress

Extend stress and be to use (strain) Ou Lienteke (オリエ Application テ Star Network) system day western sieve (テ Application シロ Application) UCT-100 elongation test machine; The plate of width 10mm, length 100mm after keeping 5 minutes under 100 ℃ the environment; When making elongation with 300mm/ minute, the MV of the stress value of 100% elongation moment point of plate length direction and transverse direction.

[embodiment 1]

Under the condition of 120 ℃ of preheatings, heat four hours to optics as raw material with vinyl resin [this close peck of Sumitomo Chemical (strain) is thought (スミペ Star Network ス) MGSS]; Is it that 34 single shaft forcing machine, second section 50mm, L/D are that the series connection forcing machine of 28 single shaft forcing machine is supplied with to first section 35mm, L/D; And the high pressure gas feedway outside being arranged on the forcing machine machine is to cross 38 ℃, 15Mpa of super critical condition; Supply with the nozzle of carbonic anhydride on the bore section that is arranged on first section forcing machine fusing compression unit, make in resin dissolving and mix.At this moment the feed rate of carbonic anhydride is the discharge-amount 14.7kg/h of relative forcing machine and set the ratio of carbonic anhydride for 0.38kg/h.At this moment be that extrusion temperature is 240 ℃ at first section, is 200 ℃ at second section.

Spue it and the result that forms plate is from the mould of slit width 150mm, interval of slit 0.8mm, obtained the white foaming plate of mean thickness 230 μ m, width 88mm.

With slicing machine the thin slice section is not cut off with destroying; Use the section that cuts off scanning electron microscope S-2100A type [(strain) Hitachi system] to observe with 500 times; The result is that the center in bubble footpath is 14 μ m, the bubble footpath that has the following scope of 20 μ m more than 80% of bubble.The voidage of bubble is 76% according to density calculation.

The result who removes shaggy part the reflectivity of back this plate visible-range of mensuration is 85%, and total light transmittance is 6%.

Use the strong elongation apparatus for automatically measuring of thin slice [Ou Lienteke (オリエ Application テ Star Network) system day western sieve (テ Application シロ Application) AMF/RTA-100]; Condition with test portion dimension width 10mm * test portion intervals of lengths 100mm, 100 ℃ of temperature, extension speed 200mm/ minute is measured; The result is that to extend elongation at failure be 141%, is 12.0Mpa at 100 ℃, extension stress during 100% elongation.For the purpose of prudent, implemented simple and easy forming test, the result is that plasticity is good.

[embodiment 2]

Except setting the discharge-amount of forcing machine for 14.3kg/h, supplying with carbonic anhydride with the ratio of 0.03kg/h, likewise carry out with embodiment 1, the result who has formed plate has obtained transparent level and smooth plate.On one side be heated to 90 ℃ to this plate, be, foam and bleach turbid Yi Bian put the result of the 28kPa that reduces pressure in the moisture eliminator (Vakuumkammer) into.

Use the white plate that obtains (mean thickness 205 μ m) with embodiment 1 same method and to observe, the result is that the center in bubble footpath is 10 μ m, the bubble footpath that has the following scope of 20 μ m more than 85% of bubble.And voidage is 56%.The reflectivity of this plate visible-range is 88%, and total light transmittance is 7%.Some is coarse a little for condition of surface, but it is low to be unlikely to reflectivity.

Extension elongation at failure under 100 ℃ is 195%, is 12.5Mpa at 100 ℃, extension stress during 100% elongation.

[embodiment 3]

Being heated to 50 ℃ on one side, Yi Bian put the 28kPa that reduces pressure in the moisture eliminator into the transparent panel that obtains with embodiment 2 same methods.

The bubble size of the foaming plate that consequently obtains diminishes, and the center in bubble footpath is 7 μ m, and 100% of bubble has the bubble footpath of the following scope of 20 μ m.And voidage is 32%.The reflectivity of this plate visible-range is 89%, and total light transmittance is 10%.Condition of surface is no problem.

[embodiment 4]

Be being heated to 140 ℃ on one side, Yi Bian put the 28kPa that reduces pressure in the moisture eliminator into specifically with the transparent panel that obtains with embodiment 2 same methods.

It is big that the bubble size of the foaming plate that consequently obtains becomes, and deviation becomes big.The center in bubble footpath is 18 μ m, and 80% of bubble has the bubble footpath of the following scope of 20 μ m.And voidage is 61%.The reflectivity of this plate visible-range is 86%, and total light transmittance is 9%.The surface has the vestige of broken bubble everywhere.

[embodiment 5]

Use main extruder to extrude (A layer) to carry out two sections with embodiment 1 same material, device, operating condition; Also have that to be to use 45mm, L/D as secondary forcing machine be 34 single shaft forcing machine; Supply with carbonic anhydride to the resin identical [this close peck of Sumitomo Chemical (strain) is thought (スミペ Star Network ス) MGSS] with main extruder; And extrude (B layer); Utilization is arranged on the three-decker of infeed mean synthetic (B layer)/(A layer)/(the B layer) of layer through carrying out coextrusion to both in front of the mould, likewise forms plate with embodiment 2.And likewise in moisture eliminator, be exposed in the decompression with embodiment 2, make foaming.

(mean thickness 245 μ m) are different with embodiment 2 for the white layer plywood that obtains, and the surface is level and smooth in the extreme.Use with embodiment 1 same method and observe, the result is that the center in bubble footpath is 8 μ m, and 90% of bubble has the bubble footpath of the following scope of 20 μ m.And voidage is 50%.The reflectivity of this plate visible-range is 89%, and total light transmittance is 9%.

Extension elongation at failure under 100 ℃ is 163%, is 13.3Mpa at 100 ℃, extension stress during 100% elongation.

[comparative example 1]

Except the carbonic anhydride increment to 0.6kg/h, likewise carry out with embodiment 1, carried out forming plate and the foaming plate that obtains white.But will behind mould, constantly break bubble, produce plosive.Fluctuation is seen on surface at plate, and voidage also is increased to 85%.

[comparative example 2]

Except the carbonic anhydride decrement to 0.1kg/h, likewise carry out with embodiment 1, carried out the formation plate and obtained translucent plate.Bubble directly is distributed in the scope of 20～100 μ m, and particularly big bubble accounts for more than 50% more than the 50 μ m.

[comparative example 3]

Except further the carbonic anhydride decrement to 0.05kg/h, likewise carry out with embodiment 1, carried out forming plate and obtained roughly transparent plate.But there is bubble big more than the 2mm irregularly to occur everywhere.

[comparative example 4]

Except not supplying with the carbonic anhydride, likewise carry out with embodiment 1, carry out forming plate and obtained transparent plate.Likewise in moisture eliminator, reduce pressure this plate and embodiment 2, but do not see bubble generation.

[comparative example 5]

Put into the transparent plate that do not foam that embodiment 2 obtains in the moisture eliminator and reduce pressure while being heated to 40 ℃, but do not see bubble generation.

[comparative example 6]

Put into the transparent plate that do not foam that embodiment 2 obtains in the moisture eliminator and reduce pressure while being heated to 210 ℃, the result is that there is the such foaming of balloon on the surface everywhere.

[comparative example 7]

The transparent plate that do not foam that obtains embodiment 2 on one side likewise is heated to 90 ℃ of one side with embodiment 2 and puts in the moisture eliminator and reduce pressure, and this state held one hour.The plate that the plate that obtains obtains than embodiment 2, bubble growth big, the center in bubble footpath is 30 μ m, 60% of bubble has the bubble footpath of the following scope of 20 μ m.The reflectivity of this plate visible-range is 75%, and total light transmittance is 6%.

Foaming buttress of the present invention can be useful in reflector, packing material, steel plate lamination with in material, the separator material etc. according to its white property, adverse environment resistant property, heat retaining property, insulativity, micro bubble contain sexual, but its scope of application is not limited thereto.Foaming plate of the present invention is used light reflecting board as the employed flat light source of backlight mechanism of liquid crystal indicator, can use rightly especially.

Claims

1. light reflecting board, its nothing that contains thermoplastic resin is extended the foaming plate, the bubble that has 0.1～20 mu m range in the bubble that is comprised in the plate of this foaming plate more than 80% directly, and voidage is 20～80%.

2. light reflecting board as claimed in claim 1, wherein, the extension elongation at failure under 100 ℃ environment, measured of foaming plate is more than 100%, and is below the 50Mpa at 100 ℃, the extension stress of 100% elongation.

3. light reflecting board as claimed in claim 1, wherein, the melted state flowability that is as the criterion with ASTMD1238-98 of thermoplastic resin is 0.5～44g/10 minute.

4. light reflecting board as claimed in claim 1, wherein, thermoplastic resin is vinyl resin and/or is methacrylic resin.

5. light reflecting board as claimed in claim 1, wherein, the foaming plate contains the nuclear agent of 0～3% weight.

6. light reflecting board as claimed in claim 1, wherein, the foaming plate has duplicated embossing at least on single face.

7. light reflecting board as claimed in claim 1, wherein, the reflectivity of the visible-range of foaming plate is more than 85%, total light transmittance is below 10%.

8. light reflecting board as claimed in claim 1, wherein, the foaming plate is two-layer above laminated wood, disposes each described foaming plate of one deck such as claim 1～7 in this two-layer laminated wood at least.

9. light reflecting board as claimed in claim 8, wherein, the foaming plate is the laminated wood that disposes one deck non-foam layer at least.

10. light reflecting board as claimed in claim 8, wherein, the reflectivity of the visible-range of foaming plate is more than 85%, total light transmittance is below 10%.

11. light reflecting board as claimed in claim 1, wherein, it has executed the processing that is shaped to described foaming is firm and hard.

12. a display unit, wherein, it has used each described light reflecting board of claim 1～11.

13. the method for manufacture like each described light reflecting board of claim 1～11 wherein, comprises the thermoplastic resin that has dissolved gas through extruding the operation that makes foaming.

14. the method for manufacture like each described light reflecting board of claim 1～11 wherein, comprising:

Under acomia blister attitude, form the melt polymer of the thermoplastic resin that has dissolved gas the operation of plate and make the operation that produces bubble in a vacuum through under 50～200 ℃ temperature condition, exposing plate.

15. the method for manufacture of light reflecting board as claimed in claim 13 is characterized in that, it has dissolved the thermoplastic resin of gas and has not had the thermoplastic resin of gas dissolved to extrude together.

16. one kind like claim 1～11 each described light reflecting board manufacturing use extrusion device; It is the forcing machine that possesses screw rod, cylinder barrel and cylinder barrel thermoregulation mechanism; It is characterized in that; At the inner face of the part of this cylinder barrel, possess and be used for from being arranged on the nozzle that the outside high pressure gas feed unit gas supplied of this cylinder barrel imports.

17. extrusion device is used in light reflecting board manufacturing as claimed in claim 16, wherein, said nozzle is made up of annular metal with minute aperture or pottery.

18. light reflecting board as claimed in claim 17 is made all extrusion devices, wherein, said annular metal is made up of the material of sintering metal powder or steel fiber.

19. use manufacturing installation like each described light reflecting board of claim 1～11 for one kind, wherein, dispose: vacuum chamber device, it possesses the chamber and the sealing mechanism that can reduce pressure inside after the casting roller of sheet forming machine and/or casting roller; Vacuum generating device, it is attached to this vacuum chamber device.

20. light reflecting board as claimed in claim 19 is used manufacturing installation, wherein, said vacuum chamber device can reduce pressure the chamber interior that can reduce pressure to below the 30Kpa.