TWI472564B - A thermoplastic resin foam, a thermoplastic resin foam manufacturing method, and a light reflection material - Google Patents

Description

Thermoplastic resin foam, method for producing thermoplastic resin foam, and light reflecting material

The present invention relates to a thermoplastic resin foam having uniform and fine bubbles and a method for producing the same. Further, the present invention relates to a light reflecting material using a thermoplastic resin foam having uniform and fine bubbles.

Conventionally, as a reflector for illumination or liquid crystal backlight, a coating material having excellent light reflectivity is applied to a metal plate, or a resin film having excellent light reflectivity is laminated on a metal plate. In recent years, in the fields of lighting fixtures, liquid crystal displays, and the like, further power saving and high efficiency have been demanded. Especially in the field of electronic billboards or displays, the need for space saving is also increasing, and the above-mentioned reflectors are difficult to cope with space saving.

Therefore, a resin sheet having fine bubbles (for example, about 1 μm) having excellent light reflectivity is used as a reflector for illumination or liquid crystal backlight (for example, see Patent Document 1). However, the resin sheet described in Patent Document 1 is obtained by foaming a polyethylene terephthalate of a crystalline resin, which causes an obstacle in moldability.

On the other hand, a foam in which an amorphous resin is used without using a crystalline resin is excellent in moldability, but at the time of foaming, not only fine bubbles but also large bubbles of 1 mm or more are likely to be generated, which is difficult. It is used as a molded article of various materials such as a light-reflecting material.

Therefore, an amorphous thermoplastic resin sheet having a uniform cell diameter by foaming at a glass transition temperature (Tg) which is less than the amorphous thermoplastic resin has been proposed (for example, see Patent Document 2). However, if foaming is carried out at a temperature lower than Tg, the expansion ratio cannot be increased, so that not only the desired properties are not obtained, but also the cost is disadvantageous.

Patent Document 1: Japanese Patent No. 2713556

Patent Document 2: Japanese Patent No. 3459447

An object of the present invention is to provide a thermoplastic resin foam having a fine and uniform cell diameter and excellent moldability, and a light-reflecting member having high light reflectance using the same. Further, an object of the present invention is to provide a method for producing a thermoplastic resin foam having a fine and uniform cell diameter.

In order to solve the above problems, the inventors of the present invention have found that by adding a specific amount of a molten crystal nucleating agent to an amorphous thermoplastic resin, it is possible to produce a amorphous having a fine and uniform bubble diameter. Thermoplastic resin foam. The present invention has been completed on the basis of this finding.

That is, the present invention provides:

<1> A thermoplastic resin foam containing 0.25 to 2.5 parts by mass of a molten crystal nucleating agent (B) per 100 parts by mass of the amorphous thermoplastic resin (A). The composition was obtained by foaming, and had bubbles having an average cell diameter of 10 μm or less inside.

<2> The thermoplastic resin foam according to the above-mentioned item (1), wherein the molten crystal nucleating agent (B) is a compound represented by the following formula (1).

General formula (1) R ¹ -(CONHR ² ) _a

[Wherein, R ¹ represents a saturated or unsaturated, having 2 to 30 carbon atoms of the aliphatic polycarboxylic acid residue, a saturated or unsaturated 4 to 28 carbon atoms of the alicyclic polycarboxylic acid residue, or a C 6 ～28 aromatic polycarboxylic acid residue. R ² represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms or a cycloalkenyl group, a phenyl group, a naphthyl group or an anthracenyl group. a represents an integer from 2 to 6. ]

<3> The thermoplastic resin foam according to <1> or <2>, wherein the molten crystal nucleating agent (B) is selected from the group consisting of 1,3,5-benzenetricarboxylic acid three (three-stage) Butyl decylamine), 1,3,5-benzenetricarboxylic acid tricyclohexyl decylamine, 1,3,5-benzenetricarboxylic acid tris(2-methylcyclohexyl decylamine), 1,3,5-benzene Tris(4-methylcyclohexyldecylamine) formic acid, 1,4-cyclohexanedicarboxylic acid dianilide, 1,4-cyclohexanedicarboxylic acid dicyclohexyl Indoleamine, 1,4-cyclohexanedicarboxylic acid dibenzyl decylamine, 2,6-naphthalene dicarboxylic acid dicyclohexyl decylamine, 1,2,3,4-butane tetracarboxylic acid tetracyclohexyl fluorene At least one guanamine compound of an amine and tetrakis-aniline of 1,2,3,4-butanetetracarboxylic acid.

The thermoplastic resin foam according to any one of <1> to <3> wherein the thermoplastic resin foam is V-0, V in the vertical burning test method of UL-94. -1 or V-2.

The thermoplastic resin foam according to any one of <1> to <4> wherein the amorphous thermoplastic resin (A) is a polycarbonate.

<6> A light-reflecting material which is formed by using the thermoplastic resin foam according to any one of <1> to <5>. as well as

<7> A method for producing a thermoplastic resin foam, comprising: melt-dispersing 0.25 to 2.5 parts by mass of a molten crystal nucleating agent to obtain heat by 100 parts by mass of the amorphous thermoplastic resin; a step of plasticizing the composition of the resin; curing the composition, impregnating the composition with an inert gas under pressure, thereby precipitating the molten crystal nucleating agent; and treating the composition impregnated with the inert gas The step of heating at a temperature equal to or higher than the glass transition temperature of the amorphous thermoplastic resin under open pressing.

Here, the above polycarboxylic acid residue means a residue in which all carboxyl groups are removed from each polycarboxylic acid.

According to the present invention, it is possible to provide a thermoplastic resin foam having a fine and uniform cell diameter and excellent moldability, a method for producing the same, and a light-reflecting member having a high light reflectance using the same.

The above and other features and advantages of the present invention will be apparent from the description.

The thermoplastic resin foam of the present invention can be obtained by foaming a thermoplastic resin composition containing the amorphous thermoplastic resin (A) and the molten crystal nucleating agent (B). First, an amorphous thermoplastic resin used in the thermoplastic resin foam of the present invention will be described.

(A) Amorphous thermoplastic resin

In the present invention, the amorphous thermoplastic resin means a thermoplastic resin which does not contain a crystalline component. The amorphous thermoplastic resin in the present invention may, for example, be a polyphenylene ether, a polymer alloy of polyphenylene ether and polystyrene, a polymethyl methacrylate, a polycarbonate, a polyether quinone, or a polyether oxime. Polyallyl sulfone, polyarylate, polyamidoximine, cyclic olefin copolymer, norbornene resin, thermoplastic elastomer, and the like. These may be used singly or in combination of two or more. Among them, polycarbonate is preferred from the viewpoint of easiness of flame retardation and mechanical properties of the foamed sheet.

In the present invention, from the viewpoint of recycling, the thermoplastic resin is preferably non-crosslinked. In the thermoplastic resin of the present invention, the mass fraction of the crosslinked portion in the thermoplastic resin (hereinafter, also referred to as the degree of crosslinking in the present specification) is preferably less than 10%. It is also possible to add a crosslinking agent or a crosslinking assistant so that the degree of crosslinking of the thermoplastic resin is preferably less than 10%.

(B) Melt-type crystal nucleating agent

The crystallization nucleating agent is a nucleating agent which is characterized in that it is melt-dispersed in a resin during melt-kneading when it is added to a thermoplastic resin, and is solidified (crystallized) during precipitation and solidification. . In the present invention, the molten crystal nucleating agent (B) is melt-dispersed in the amorphous thermoplastic resin (A) during heat molding. The molten crystal nucleating agent (B) is precipitated in the amorphous thermoplastic resin (A) during the temperature-lowering curing after molding or during gas impregnation. As a result, the molten crystal nucleating agent (B) is crystallized. During the foaming process, the precipitated molten crystal nucleating agent (B) becomes the starting point of bubble nucleation. As a result, it is possible to obtain a foam having a uniform internal bubble diameter of 10 μm or less and a large number of bubbles having a diameter of 1 mm or more. By forming the above-mentioned foam, a reflector having high reflectance can be obtained.

The molten crystal nucleating agent used in the present invention is preferably a guanamine compound having a guanamine bond. For example, nylon 6, nylon 66, nylon 6.66, nylon 6.6T, nylon 610, nylon 612, nylon MDX6, nylon 11, nylon 12, nylon 46 (all are trade names), etc. A nylon-based polymer, an amino acid, a polypeptide, an indoleamine, and the like. The guanamine compound to be used is particularly preferably a guanamine compound represented by the following formula (1).

General formula (1) R ¹ -(CONHR ² ) _a

In the formula, R ¹ represents a saturated or unsaturated, having 2 to 30 carbon atoms of the aliphatic polycarboxylic acid residue, a saturated or unsaturated 4 to 28 carbon atoms of the alicyclic polycarboxylic acid residue, or a C 6 ~ 28 aromatic polycarboxylic acid residues. R ² represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms or a cycloalkenyl group, a phenyl group, a naphthyl group or an anthracenyl group. a represents an integer from 2 to 6.

The guanamine compound in the present invention may, for example, be tris(tert-butyl decylamine) 1,3,5-benzenetricarboxylic acid, tricyclohexyl decylamine 1,3,5-benzenetricarboxylic acid, 1,3,5 -tris(3-methylcyclohexyldecylamine), 1,3,5-benzenetricarboxylic acid tris(4-methylcyclohexyldecylamine), 1,4-cyclohexanedicarboxylic acid diterpene Aniline, 1,4-cyclohexanoic acid dicarboxylic acid dicyclohexyl decylamine, 1,4-cyclohexanoic acid dicarboxylic acid bis(2-methyldicyclohexyl decylamine), 1,4-cyclohexanoic acid dicarboxyl Acid dibenzyl decylamine, 2,6-naphthalene dicarboxylic acid dicyclohexyl decylamine, 1,2,3,4-butane tetracarboxylic acid tetracyclohexyl decylamine and 1,2,3,4-butane Tetrabenzoic acid tetracarboxylic acid may be used alone or in combination of two or more. Among them, tricyclohexyl decylamine 1,3,5-benzenetricarboxylic acid or N,N'-dicyclohexyl-2,6-naphthalene dicarboxylic acid dicyclohexyl decylamine is particularly preferred.

The amount of the guanamine compound to be added in the present invention is 0.25 to 2.5 parts by mass, preferably 0.5 to 1.5 parts by mass, more preferably 0.5 to 1.0 part by mass, per 100 parts by mass of the amorphous thermoplastic resin. If the amount is too small, the suppression effect of the large bubbles cannot be expected. On the other hand, if the compounding amount is too large, the guanamine compound cannot be melted, and thus the surface of the product is precipitated as a foreign matter.

In the present invention, the thermoplastic resin foam is preferably V-0, V-1 or V-2 which satisfies the vertical burning test method of UL-94. In order to satisfy the above criteria, the resin composition before foaming preferably contains a flame retardant. The type of the flame retardant which can be used in the present invention is not particularly limited, and may be any flame retardant used for a polymer such as rubber or resin. For example, a bromine-based flame retardant, a phosphorus-based flame retardant, a nitrogen-based flame retardant, an inorganic flame retardant, an organic metal salt compound, a polyoxygen resin-based flame retardant, a fluororesin-based flame retardant, and a terpene A resin-based flame retardant, a non-flammable amorphous thermoplastic resin, and the like. In the present invention, the above-mentioned flame retardant may be used alone or in combination of two or more.

Examples of the flame retardant of the bromine-based compound include brominated bisphenol A type epoxy polymer, pentabromobenzyl acrylate, brominated polycarbonate oligomer, and three Flame retardant, tetrabromobisphenol A, bis(tribromophenoxy)ethane, tetrabromobisphenol A-bis(2-hydroxyethyl ether), tetrabromobisphenol A-bis (2,3-dibromo) Propyl ether), tetrabromobisphenol A-bis(diallyl ether), hexabromocyclododecane, polydibromophenyl ether, decabromodiphenyl ether, brominated phthalate, etc. Not limited to this. Among them, decabromodiphenyl ether is preferred.

When a bromine-based compound is used as the flame retardant, the content of the flame retardant is 0.1 to 20 parts by mass, preferably 0.5 to 15 parts by mass, more preferably 1 to 100 parts by mass of the amorphous thermoplastic resin. ~10 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

A flame retardant of a phosphorus compound is preferably a phosphate compound. The phosphate compound in the present invention may, for example, be trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributyloxyethyl phosphate, triphenyl phosphate, tricresyl phosphate or toluene phosphate. Diphenyl ester, octyl diphenyl phosphate, tris(2-ethylhexyl) phosphate, diisopropylphenyl phosphate, trixyl phosphate, cisplatin phosphate, trinaphthyl phosphate , bisphenol A diphosphate, hydroquinone diphosphate, resorcinol diphosphate, resorcinol-diphenyl phosphate, trioxyphenyl triphosphate, toluene diphenyl phosphate, ammonium polyphosphate (ammonium Polyphosphate), etc., but is not limited to this. Further, a compound obtained by introducing various substituents thereto or the like, or an oligomer or a polymer thereof may be mentioned. Among them, ammonium polyphosphate is preferred.

When a phosphorus-based compound is used as the flame retardant, the content of the flame retardant is 1 to 30 parts by mass, preferably 3 to 25 parts by mass, more preferably 5 parts by mass based on 100 parts by mass of the amorphous thermoplastic resin. ~ 15 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

Examples of the nitrogen-based flame retardant include melamine, cyanuric acid, melamine cyanurate, and melamine phosphate. The compound, melamine polyphosphate, melamine sulfate, urea, isocyanurate, etc., but is not limited thereto. Among them, melamine polyphosphate is preferred.

When a nitrogen-based compound is used as the flame retardant, the content of the flame retardant is 1 to 100 parts by mass, preferably 5 to 75 parts by mass, more preferably 10 parts by mass based on 100 parts by mass of the amorphous thermoplastic resin. ~50 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

Examples of the inorganic flame retardant include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, magnesium carbonate, antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonite, and guanidine sulfamate. Sulfamate), guanidine phosphate, guanylurea phosphate, melamine phosphate, cesium salt, zinc borate, ammonium borate, boric acid, aluminum ammonium hydrogencarbonate, ammonium molybdate, molybdenum oxidation , molybdenum oxide, benzoylferrocene, iron strontium, tin oxide, hydrated tin compound, tin stannate and other tin compounds, aromatic sulfoximine, acetamidine, aldehyde, 8-hydroxyquinoline Inorganic complexes such as metal salts of dimethylglyoxime, phosphorus-nitrogen compounds, calcium-aluminate hydrates, calcium-aluminum-tellurates, zirconium compounds, dawsonite, aliphatic sulfonic acids a salt, an aromatic sulfonate, an aromatic sulfonamide salt, a sulfimide salt, a quinone imine diphosphate salt, a fluorinated aliphatic sulfonate, an alkali or an alkaline earth metal salt, But it is not limited to this. Among them, magnesium hydroxide is preferred.

When an inorganic compound is used as the flame retardant, the content of the flame retardant is 10 to 200 parts by mass, preferably 30 to 150 parts by mass, more preferably 50% by mass based on 100 parts by mass of the amorphous thermoplastic resin. ~100 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

The organometallic salt compound may, for example, be a metal salt of an aromatic sulfonic acid or a metal salt of a perfluoroalkanesulfonate. The type of the metal of the metal salt may, for example, be an alkali metal or an alkaline earth metal. The organometallic salt compound in the present invention may, for example, be a potassium salt of 4-methyl-N-(4-methylphenyl)sulfonyl-benzenesulfonamide, potassium dibenzoin-3-sulfonate or the like. Potassium phenylhydrazine-3-3-disulfonate, sodium p-toluenesulfonate, potassium perfluorobutanesulfonate, etc., but is not limited thereto. Among them, potassium perfluorobutanesulfonate is preferred.

When the organometallic salt compound is used as the flame retardant, the content of the flame retardant is 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, more preferably 100 parts by mass based on 100 parts by mass of the amorphous thermoplastic resin. 0.1 to 2 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

Examples of the polyoxygenated resin-based flame retardant include polyorganosiloxanes such as poly(dimethyloxane), poly(diphenylphosphoxane), and poly(methylphenyloxane), and rings. Oxygen-denatured polyorganosiloxane, methacryl-based polyorganosiloxane, amine-modified polyorganosiloxane such as eucalyptus oil, oxime resin, ruthenium rubber, ruthenium powder, etc., but are not limited thereto. Among them, poly(dimethyloxane) is preferred.

When a polyoxygenated resin-based flame retardant is used as the flame retardant, the content of the flame retardant is 0.05 to 8 parts by mass, preferably 0.1 to 5 parts by mass, per 100 parts by mass of the amorphous thermoplastic resin. More preferably, it is 0.1 to 2 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

The fluororesin-based flame retardant may, for example, be a fluorine-based metal salt, polytetrafluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, or a fluorine-based sulfimine, but is not limited thereto. Among them, polytetrafluoroethylene is preferred.

When a fluororesin-based flame retardant is used as the flame retardant, the content of the flame retardant is 0.05 to 8 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the amorphous thermoplastic resin. Preferably, it is 0.1 to 2 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

The terpene resin-based flame retardant may, for example, be an α-pinene resin, a β-pinene resin, an anthracene resin, a dipentene resin, a β-pinene/indene resin, a hydrogenated hydrazine resin, an aromatically modified terpene resin, or a phenol. Denatured terpene resin or the like, but is not limited thereto. Among them, α-pinene resin is preferred.

When a terpene resin-based flame retardant is used as the flame retardant, the content of the flame retardant is 1 to 30 parts by mass, preferably 2 to 20 parts by mass, based on 100 parts by mass of the amorphous thermoplastic resin. More preferably, it is 5 to 15 parts by mass. If the amount is too small, the desired flame retardancy cannot be maintained, and if it is too large, the mechanical properties are affected.

The non-flammable amorphous thermoplastic resin may, for example, be polyvinyl chloride, polyether quinone, polyether oxime, polyfluorene or polyamidoximine, but is not limited thereto. Among them, polyvinyl chloride is preferred.

For other flame retardants, ammonium borate or zinc borate can also be used. Further, in the present invention, the flame retardant may be used alone or in combination of two or more.

In the present invention, the thermoplastic resin before foaming may be appropriately blended with a crystallization nucleating agent, a crystallization accelerator, or a bubble nucleation in addition to the molten crystal nucleating agent without impairing the object of the present invention. Agents, antioxidants, antistatic agents, anti-UV agents, light stabilizers, fluorescent brighteners, pigments, dyes, compatibilizers, lubricants, enhancers, plasticizers, tackifiers, viscosity reducers, etc. . Further, a resin layer containing the above additive may be laminated on the reflective material composed of the obtained amorphous thermoplastic resin foamed sheet, or a coating material containing the above additive may be applied. In view of the deterioration of the amorphous thermoplastic resin by the ultraviolet ray, it is preferable to apply a layer containing an ultraviolet ray-resistant agent or the like to the reflective material composed of the amorphous thermoplastic resin foamed sheet. At least on one surface.

Hereinafter, a method for producing the amorphous thermoplastic resin foamed sheet of the present invention will be described.

The amorphous thermoplastic resin (A) is added to a mixture of the molten crystal nucleating agent (B) and, if necessary, other resins or additives, and is melt-kneaded by, for example, a kneader or an extruder, thereby producing Resin composition. The kneading conditions such as the kneading temperature or the kneading time can be appropriately set in the melting temperature of the amorphous thermoplastic resin (A) and the molten crystal nucleating agent (B). For example, in the case of polycarbonate, it is preferably at least 270 °C. Further, the pressure can be appropriately set. The resin composition is formed into a sheet shape by using an extruder or the like, and the resin sheet and the separator are superposed and wound to form a roll. The roller is held in a pressurized inert gas atmosphere, whereby the resin sheet contains an inert gas. In addition, the resin sheet containing an inert gas is heated under normal pressure to a glass transition temperature (Tg) of the amorphous thermoplastic resin (A) to be foamed. By heating to a temperature higher than Tg, generation of uneven bubbles can be suppressed. Thus, a thermoplastic resin foamed sheet can be obtained. In the foamed sheet of the thermoplastic resin, the mass fraction of the crosslinked portion is less than 10%. The degree of crosslinking can be determined by immersing the foamed sheet in a solvent capable of dissolving the non-crosslinked portion, and calculating the weight fraction of the insoluble portion relative to the total weight of the original foam. For example, in the case of a polycarbonate foam, the soluble portion can be removed by stirring the foam in a dichloromethane solution while stirring for about 12 hours.

In the present invention, the inert gas may, for example, be hydrazine, nitrogen, carbon dioxide or argon. Among them, carbon dioxide is preferred from the viewpoint of gas permeability (speed, solubility) of the resin.

The inert gas permeation time and the inert gas impregnation amount of the resin sheet to the saturated state differ depending on the type of the resin to be foamed, the type of the inert gas, the permeation pressure, and the thickness of the sheet.

Further, in this method, the resin sheet may contain an organic solvent before the drum composed of the resin sheet and the separator contains an inert gas in a pressurized inert gas atmosphere.

The organic solvent may, for example, be benzene, toluene, methyl ethyl ketone, ethyl formate, acetone, acetic acid, or the like. Alkane, m-cresol, aniline, acrylonitrile, dimethyl phthalate, nitrate, methane, benzyl alcohol, and the like. Among them, acetone is preferred from the viewpoint of operability and economy.

In the present invention, the bubbles of the thermoplastic resin foam of the present invention have an average diameter of 10 μm or less. Among them, it is preferably 5 μm or less, and particularly preferably 2 μm or less. If the average bubble diameter is too large, the desired high reflectance cannot be obtained.

The foaming ratio of the foam of the present invention is preferably from 1.1 to 10, more preferably from 2 to 5.

In the present invention, the total reflectance of the light of the thermoplastic resin foam is preferably 97% or more. Among them, it is more preferably 98.5% or more, and particularly preferably 99% or more. In addition, the total reflectance described here is a 550 nm wavelength of an alumina white plate (210-0740: manufactured by Hitachi High-Tech Fielding Corporation) using a spectrophotometer (U-4100: manufactured by Hitachi Advanced Technology Co., Ltd.). The reflectance is 100%, and is expressed as a relative value.

Next, the light reflecting material of the present invention will be described.

In the thermoplastic resin foam of the present invention, bubbles having a fine and uniform bubble diameter are formed. The thermoplastic resin foam of the present invention has high reflectance by the fine and uniform bubbles. The thermoplastic resin foam of the present invention can be used for, for example, a reflector for illumination, a reflector for an electronic signboard, a reflector for a liquid crystal television or a backlight for a mobile phone, etc., in order to utilize high reflectance and good formability.

[Examples]

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

[Examples 1 to 9 and Comparative Examples 1 to 7]

Table 1 shows the contents of the respective components of the resin compositions of Examples 1 to 9 and Comparative Examples 1 to 7 (the numbers in the table refer to parts by mass unless otherwise specified). Each of the components shown in the table was melt-kneaded by a co-rotating extruder to obtain a sheet before foaming. The temperature at the time of extrusion is shown in the table of the examples and the comparative examples at the extrusion temperature.

The ingredients of the ingredients shown in the table are as follows.

Amorphous thermoplastic resin (A)

A1: "SI8000L" (trade name, Sumitomo Dow Industrial Co., Ltd.), flame retardant polycarbonate, amorphous

A2: "NOVAREX S2000" (trade name, manufactured by Mitsubishi Engineering Plastics Co., Ltd.), polycarbonate, amorphous

A3: FS1300 (trade name, manufactured by SUMITOMO BAKELITE Corporation), polyether oxime, amorphous

A4: SA1206 (trade name, manufactured by Unitika), polyethylene terephthalate, crystallinity

Melt crystal nucleating agent (B)

B1: "NJSTAR TF-1" (trade name, manufactured by Nippon Chemical and Chemical Co., Ltd.), tris-hexyl decylamine 1,3,5-benzenetricarboxylate

B1: "NJSTAR NU100" (trade name: manufactured by Nippon Chemical and Chemical Co., Ltd.), N,N'-dicyclohexyl-2,6-naphthalene dicarboxylic acid dicyclohexyl decylamine

Flame retardant

C1: "X-40-9805" (trade name: Shin-Etsu Chemical Co., Ltd.), polyoxygenated compound

C2: "Hostaflon TF1620" (trade name, manufactured by Sumitomo 3M), Teflon

Next, the sheet before foaming was placed in a pressure vessel, and impregnated with carbon dioxide gas at a pressure of 6 MPa at 17 ° C to permeate it. The penetration time is more than 48 hours.

The sheet in which the carbonic acid gas was permeated was taken out from the pressure vessel, and immediately placed in a thermostatic chamber set at a predetermined temperature to be foamed. The foaming time is within 60 seconds. The temperature at the time of foaming is shown in Table 1 as the foaming temperature.

The film after foaming was subjected to the following evaluation. The evaluation results of the obtained Examples 1 to 9 and Comparative Examples 1 to 7 are shown in Table 1.

(1) Melt dispersibility

The surface of the pre-expanded sheet obtained by extrusion was visually observed. When the molten crystal nucleating agent was melt-dispersed at the time of kneading, the aggregate of the nucleating agent could not be visually observed, and it was judged that the melt dispersibility was good, and if it was aggregated, it was judged to be defective. Further, in the case where a molten crystal nucleating agent is not used, the melt dispersibility is not evaluated.

(2) Whether there are huge bubbles

The surface of the sheet before foaming obtained by extrusion was visually observed, and if there were bubbles having a diameter of more than 1 mm, it was judged that there was a large bubble, and if not, it was judged that there was no large bubble.

(3) Foaming ratio

The ratio ρs/ρf of the specific gravity (ρf) of the foamed sheet measured by the water substitution method to the specific gravity (ρs) of the resin before foaming was calculated.

(4) Bubble diameter

It is obtained according to ASTM D3576-77. A scanning electron microscope (SEM) photograph of the cross section of the photographing sheet was drawn in a horizontal direction and a vertical direction on the photographed SEN photograph, and the average value of the straight line spanning the chord length t of the bubble was obtained. Let the magnification of the photograph be M, and substitute the following formula to obtain the average bubble diameter d.

d=t/(0.616×M)

Among them, the large bubble portion has a large difference in the diameter of the bubble with respect to the fine portion, and is removed for measurement.

(5) Reflectivity

The total reflectance at a wavelength of 550 nm was measured using a spectrophotometer (U-4100: manufactured by Hitachi Advanced Technology Co., Ltd.) under the condition of a slit slit of 4 nm. In Table 1, the total reflectance of each of the foamed sheets when the total reflectance of the white plate (210-0740: manufactured by Hitachi High-Tech Fielding Corporation) to which the fine powder of alumina was fixed was displayed as a relative value.

(6) Formability

The type reproducibility (sharpness of the edge, depression of the bottom surface, etc.) of the foamed sheet after molding was visually judged. When the type reproducibility is high, it is judged to be good, and when it is not good, it is judged to be bad.

(7) Flame retardancy

The sheet after foaming and before forming was cut into a predetermined size, and evaluated according to the 50W (20 mm) vertical burning test method of Underwriter Laboratories UL-94, 5th Edition (1996).

(8) Crosslinking degree

The foamed sheet was immersed in a dichloromethane solution and stirred for 12 hours. The weight of the foamed sheet before and after the immersion was measured, and the degree of crosslinking was determined by dividing the weight after immersion by the weight before immersion.

As is apparent from the results of Table 1, the addition of the molten crystal nucleating agent to the amorphous thermoplastic resin reduces the generation of large bubbles. At the same time, this foam has a high reflectance.

The present invention can provide a thermoplastic resin foam having a fine and uniform cell diameter and excellent moldability, and a light-reflecting member having high light reflectance using the same.

The present invention is described with respect to the embodiments thereof, and the invention is not intended to limit the scope of the invention, and the spirit and scope of the invention as set forth in the appended claims. Next, it should be interpreted broadly.

Claims (9)

A thermoplastic resin foam containing a thermoplastic resin composition containing 0.25 to 2.5 parts by mass of the molten crystal nucleating agent (B) in an amount of 100 parts by mass based on 100 parts by mass of the amorphous thermoplastic resin (A). It is obtained by foaming, and has bubbles having an average cell diameter of 10 μm or less inside. The thermoplastic resin foam of the first aspect of the invention, wherein the molten crystal nucleating agent (B) is a compound represented by the following formula (1); and the formula (1) R ¹ - ( CONHR ² ) _a [wherein R ¹ represents a saturated or unsaturated aliphatic polycarboxylic acid residue having 2 to 30 carbon atoms, a saturated or unsaturated alicyclic polycarboxylic acid residue having 4 to 28 carbon atoms, Or an aromatic polycarboxylic acid residue having 6 to 28 carbon atoms; R ² represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms or a cycloalkenyl group; Phenyl, naphthyl, anthracenyl; a represents an integer from 2 to 6]. The thermoplastic resin foam according to claim 1, wherein the molten crystal nucleating agent (B) is selected from the group consisting of tris(tert-butyl decylamine) 1,3,5-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid tricyclohexyl decylamine, 1,3,5-benzenetricarboxylic acid tris(2-methylcyclohexyl decylamine), 1,3,5-benzenetricarboxylic acid tris(4-A Cyclohexyl decylamine, 1,4-cyclohexanedicarboxylic acid dianilide, 1,4-cyclohexanedicarboxylic acid dicyclohexyl decylamine, 1,4 - dibenzyl decylamine cyclohexanedicarboxylate, dicyclohexyl decylamine 2,6-naphthalene dicarboxylate, tetracyclohexyl decylamine 1,2,3,4-butanetetracarboxylic acid and 1,2, At least one guanamine compound of 3,4-butane tetracarboxylic acid tetraterpene aniline. The thermoplastic resin foam of claim 2, wherein the molten crystal nucleating agent (B) is selected from the group consisting of tris(tert-butyl decylamine) 1,3,5-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid tricyclohexyl decylamine, 1,3,5-benzenetricarboxylic acid tris(2-methylcyclohexyl decylamine), 1,3,5-benzenetricarboxylic acid tris(4-A Cyclohexyl decylamine, 1,4-cyclohexanedicarboxylic acid dianilide, 1,4-cyclohexanedicarboxylic acid dicyclohexyl decylamine, 1,4 - dibenzyl decylamine cyclohexanedicarboxylate, dicyclohexyl decylamine 2,6-naphthalene dicarboxylate, tetracyclohexyl decylamine 1,2,3,4-butanetetracarboxylic acid and 1,2, At least one guanamine compound of 3,4-butane tetracarboxylic acid tetraterpene aniline. The thermoplastic resin foam according to any one of claims 1 to 4, wherein the thermoplastic resin foam satisfies V-0 and V- of the UL-94 vertical burning test method. 1 or V-2. The thermoplastic resin foam according to any one of claims 1 to 4, wherein the amorphous thermoplastic resin is polycarbonate. The thermoplastic resin foam of claim 5, wherein the amorphous thermoplastic resin is polycarbonate. A light-reflecting material which is formed by using a thermoplastic resin foam according to any one of claims 1 to 7. A method for producing a thermoplastic resin foam, which comprises the steps of: melt-dispersing 0.25 to 2.5 parts by mass of a molten crystal nucleating agent for 100 parts by mass of an amorphous thermoplastic resin to obtain a thermoplastic resin composition; a step of solidifying the composition, impregnating the composition with an inert gas under pressure, thereby precipitating the molten crystal nucleating agent; And a step of foaming the composition impregnated with the inert gas at a temperature equal to or higher than a glass transition temperature of the amorphous thermoplastic resin under an open pressure.