JP5367290B2 - Thermoplastic resin foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin foam which has high reflectance and excellent fire retardance combined with each other, and which is suited for the backlight of an illumination billboard, lighting equipment, a display and so on, and for the light reflection plate of a lighting box. <P>SOLUTION: The thermoplastic resin foam is manufactured by a manufacturing method comprising: a step to hold a resin sheet composed of a thermoplastic resin (A), a non-decabromo-based fire retardant (B), a flame-retardant aid (C), and a thermoplastic resin (D) in a pressurized inert gas atmosphere so as to make the resin sheet include the inert gas; and a step to foam the resin sheet including the inert gas by heating it to a temperature higher than the softening temperature of the thermoplastic resin under normal atmospheric pressure. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a thermoplastic resin foam containing a flame retardant and a flame retardant aid and having fine pores with an average cell diameter of 20 μm or less inside. The thermoplastic resin foam of the present invention not only has high light reflectivity, but also has good flame retardancy, so it is suitable as a light reflector for lighting signs, lighting fixtures, displays, etc. Can be used.

  Conventionally, a light reflector made by processing a synthetic resin film or sheet that reflects light into a three-dimensional shape has been proposed as a light reflector used in backlights and lighting boxes for electrical signs, lighting fixtures, displays, etc. (For example, refer to Patent Document 1).

  As a film or sheet made of a synthetic resin that reflects light, a film or sheet of a thermoplastic resin foam having many fine bubbles or pores therein (for example, see Patent Documents 2 and 3), and heat containing a filler A film or sheet of a plastic resin, in which a large number of voids are formed with a filler as a core, is known (for example, see Patent Document 4).

  The former foam with a large number of fine bubbles or pores is made by bringing the molten or solid thermoplastic resin into contact with an inert gas under pressure, then depressurizing and softening the resin under normal pressure. It can be obtained by foaming by heating above the temperature. The obtained thermoplastic resin foam film or sheet is excellent because it has a high light reflectance and a thickness of 200 μm or more because the average cell diameter is as fine as 50 μm or less. It has shape-retaining properties and can be processed into a three-dimensional shape using a thermoplastic resin foam film or sheet alone. The light reflectance of the thermoplastic resin foam film or sheet generally tends to show a higher value as the number of bubbles per unit volume increases. Therefore, the smaller the bubble diameter, the higher the light reflectivity can be achieved, and the film or sheet can be made thinner. Therefore, there is a need for a thermoplastic resin foam having a larger number of finer bubbles or pores. Yes.

  On the other hand, the thermoplastic resin film or sheet containing the latter filler is formed by forming an unstretched film or sheet containing a filler such as calcium carbonate or barium sulfate and stretching the unstretched film or sheet. It is obtained by forming a large number of voids with nuclei as a nucleus. However, since the stretching process is performed, the thickness of the obtained film or sheet becomes as thin as less than 200 μm, and the film or sheet alone does not have shape retention, and more light leaks to the back of the film or sheet. . Therefore, a plate having sufficient strength and light shielding property is disposed on the back surface of the film or sheet.

  By the way, a thermoplastic polyester resin foam obtained by mixing an elastomer with a thermoplastic polyester resin is known (for example, see Patent Document 5). However, Patent Document 5 only describes that impact resistance is improved by mixing an elastomer with a polyester-based resin, and there is no description or suggestion about the cell diameter of the obtained foam. . In the extrusion foaming method described in Patent Document 5, it is difficult to achieve finer and uniform dispersion of bubbles. Actually, a sheet prepared by mixing an elastomer with a polyester resin and extruding and foaming is used. Even if the light reflection plate is made of this extruded foam sheet with a large bubble diameter, the light reflection rate is low, so that it does not have a sufficient function as a light reflection plate.

JP 2002-122863 A JP-A-6-344457 WO97 / 01117 Publication Japanese Patent Laid-Open No. 4-296619 JP 11-49883 A

  In recent years, power saving has been demanded, and a resin film or sheet having higher light reflectance has been demanded. In particular, in the field of electric signboards and displays, there is an increasing need for space saving, and a reduction in thickness and flame resistance of a resin film or sheet that reflects light is required.

  On the other hand, Patent Document 2 describes that various additives may be added to the resin within a range that does not impair the original characteristics of the resin. Since it changes, it is necessary to select an appropriate additive.

  The present invention has been made in view of the above-described circumstances. By selecting an appropriate additive, a thermoplastic resin foam having both high light reflectance and shape retention and further excellent flame retardancy is provided. The purpose is to provide the technology to obtain.

  As a result of intensive studies to solve the above-described problems, the inventors of the present invention have added a non-decabromo flame retardant (B), a flame retardant aid (C), and a thermoplastic resin (A) to the thermoplastic resin (A). By adding a thermoplastic resin (D) having a functional group having some interaction (affinity such as polarity, hydrogen bonding or reaction) with respect to A), the thermoplastic resin (D) Obtaining a thermoplastic resin composition having the property of enabling finer bubbles by being finely dispersed in the thermoplastic resin (A) and serving as a starting point for crystal nucleation or a starting point for generating bubble nuclei. It was found that by foaming this thermoplastic resin composition, a thermoplastic resin foam having fine pores with an average cell diameter of 20 μm or less inside can be obtained.

This invention was made | formed based on the said knowledge, and provides the thermoplastic resin foam of following (1)-( 5 ).
( 1 ) For 100 parts by mass of polyethylene terephthalate as the thermoplastic resin (A),
2-10 parts by mass of a non-decabromo flame retardant (B),
Flame retardant aid (C) 0.8-4 parts by mass;
A sheet made of a thermoplastic resin to which 0.1 to 10 parts by mass of a styrene-ethylene / butadiene-styrene block copolymer as a thermoplastic resin (D) is added,
A thermoplastic resin foam having a plurality of pores therein and an average cell diameter of 20 μm or less.
(2) The thermoplastic resin foam according to (1), wherein the specific gravity is 0.7 or less.
( 3 ) The thermoplastic resin foam according to (1) or ( 2 ), wherein the non-decabromo flame retardant (B) is ethylenebispentabromobenzene.
( 4 ) The thermoplastic resin foam of (1) to ( 3 ), wherein the flame retardant aid (C) is antimony trioxide.
( 5 ) Thermoplastic resin (A), non-decabromo flame retardant (B), flame retardant aid (C), and thermoplastic resin (D) having a functional group having an affinity for thermoplastic resin (A) And holding the resin sheet containing the inert gas in a pressurized inert gas atmosphere and causing the resin sheet to contain an inert gas, and heating and foaming the resin sheet containing the inert gas under normal pressure A thermoplastic resin foam according to any one of (1) to ( 4 ), wherein the thermoplastic resin foam is produced by a production method comprising steps.

  In the present invention, the thermoplastic resin (D) has a functional group that interacts with the thermoplastic resin (A), so that the thermoplastic resin (D) is uniformly in the thermoplastic resin (A). Fine dispersion. In particular, when the thermoplastic resin (A) is a polyester-based resin, the polyester-based resin is induced to crystallize by an inert gas during the gas permeation process, and the finely dispersed thermoplastic resin (D) becomes a starting point for crystal nucleation. When this resin sheet is foamed, it has effects such as the formation of crystals, the starting point of bubble nucleation during the foaming process, and the thermoplastic resin (D) being microfoamed. In the interior, fine pores having an average cell diameter of 20 μm or less are uniformly present, and a foam having a high reflectance can be obtained. For other resins, it is considered that fine pores are generated by the same mechanism.

  The thermoplastic resin foam of the present invention has a fine average cell diameter of 20 μm or less, and thus has high light reflectance, can be made thin, and exhibits good flame retardancy. It can be suitably used as a reflector. Furthermore, since the thermoplastic resin foam of the present invention is light and rigid and has excellent dielectric properties, it can be suitably used as a speaker diaphragm or a radio wave absorber.

In the present invention, as the thermoplastic resin (A), the use of polyethylene terephthalate.

  The non-decabromo flame retardant (B) used in the present invention is not particularly limited. For example, ethylene bispentabromobenzene, TBA-bis [2,3-dibromopropyl ether], bis (3,5-dibromo-4 -Dibromopropyloxyphenyl) sulfone, tris (2,3-dibromopropyl) isocyanurate, 1,1,2,2-tetrabromoethane, 2,3-dibromo-1-propanol, hexabromobenzene, 2,4, Examples include 6-tribromoaniline, 2,4,6-tribromophenol, 2,4,6-tribromophenyl allyl ether, tetrabromophthalic anhydride, etc. Among them, ethylenebispentabromobenzene has a melting point of around 350 ° C. In addition, it is preferable because the dispersibility is good when blended with a thermoplastic resin.

In the present invention, to the thermoplastic resin (A) 100 parts by mass of the added amount of Nondekaburomu based flame retardant (B) is Ru 2-10 parts by der. More preferably, it is 2-8 mass parts. When the addition amount of the non-decabromo flame retardant (B) is less than 2 parts by mass, the flame retardancy tends to decrease, whereas when the addition amount of the non-decabromo flame retardant (B) is more than 10 parts by mass, the elongation rate is increased. There is a tendency for the mechanical strength of the sheet to decrease, such as reduction and cracking.

  The flame retardant aid (C) used in the present invention is not particularly limited, and examples thereof include compounds such as antimony and tin. Among them, antimony trioxide is preferable because it is stable in supply and inexpensive.

In the present invention, the thermoplastic resin (A) with respect to 100 parts by weight, flame retardant agent addition amount of (C) is Ru 0.8 to 4 parts by der. More preferably, it is 0.8-3.6 mass parts. When the addition amount of the flame retardant aid (C) is less than 0.8 parts by mass, the flame retardancy tends to decrease, while when the addition amount of the flame retardant aid (C) is more than 4 parts by mass, There is a tendency to be disadvantageous in terms of cost and to decrease the mechanical strength of the sheet.

In the present invention , SEBS (styrene-ethylene-butylene-styrene copolymer) is used as the thermoplastic resin (D) having a functional group having an affinity for the thermoplastic resin (A) .

In the present invention, to the thermoplastic resin (A) 100 parts by mass of the added amount of the thermoplastic resin having a functional group (D) is Ru 0.1 to 10 parts by der. More preferably, it is 0.5-5 mass parts, More preferably, it is 0.5-3 mass parts. When the addition amount of the thermoplastic resin (D) is less than 0.1 parts by mass, the foam diameter of the foam obtained tends to be large, and the dispersion of the foam tends to be non-uniform. On the other hand, when the addition amount of the thermoplastic resin (D) exceeds 10 parts by mass, it is disadvantageous in terms of cost.

  In the present invention, when the specific gravity of the foam increases, that is, the expansion ratio decreases, as a result, the light reflectance decreases due to the decrease in the bubble rate, the moldability decreases, and the weight reduction effect decreases. The specific gravity of the plastic resin foam is preferably 0.7 or less. More preferably, it is 0.65 or less, and further preferably 0.5 or less. The specific gravity of the light reflecting plate is preferably 0.05 or more.

  In the present invention, the crystallization nucleating agent, the crystallization accelerator, the cell nucleating agent, the antioxidant, the antistatic agent, and the ultraviolet ray prevention are added to the thermoplastic resin before foaming as long as the properties of the foam are not affected. Various additives such as additives, light stabilizers, optical brighteners, pigments, dyes, compatibilizers, lubricants, reinforcing agents, cross-linking agents, cross-linking aids, plasticizers, thickeners, thickeners, etc. Also good. Moreover, the resin containing the said additive may be laminated | stacked on the obtained thermoplastic resin foam, and the coating material containing the said additive may be coated.

  The method for producing the thermoplastic resin foam of the present invention is not particularly limited, but considering the mass productivity, for example, the following method is preferably used. That is, a thermoplastic resin (A), a non-decabromo flame retardant (B), a flame retardant aid (C), and a thermoplastic resin (D) having a functional group having an affinity for the thermoplastic resin (A) A roll is formed by stacking and winding the resin sheet and a separator, and the roll is held in an inert gas atmosphere with a gauge pressure of 3 MPa or more, and is not attached to the resin sheet. This is a method in which an active gas is contained and a resin sheet containing an inert gas is heated to a temperature equal to or higher than the softening temperature of the thermoplastic resin and foamed under normal pressure.

  Examples of the inert gas include helium, nitrogen, carbon dioxide, and argon. The inert gas permeation time and the inert gas permeation amount until the resin sheet is saturated vary depending on the type of resin to be foamed, the type of inert gas, the permeation pressure, and the thickness of the sheet. Carbon dioxide is particularly preferred in view of gas permeability (rate, solubility) into the resin.

  In the above method, the resin sheet may contain an organic solvent before the roll made of the resin sheet and the separator is held in the pressurized inert gas atmosphere and the resin sheet contains the inert gas. . Examples of the organic solvent include benzene, toluene, methyl ethyl ketone, ethyl formate, acetone, acetic acid, dioxane, m-cresol, aniline, acrylonitrile, dimethyl phthalate, nitroethane, nitromethane, and benzyl alcohol. Of these, acetone is more preferable from the viewpoints of handleability and economy.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to the following Example. First, measurement items and evaluation items in Examples and Comparative Examples will be described.
(Shape retention)
Using the obtained thermoplastic resin foam, a semispherical light reflecting plate having an opening diameter of 100 mm and a depth of 70 mm as shown in FIG. 1 was thermoformed by a vacuum molding machine. The obtained light reflection plate was held by hand and force was applied to observe the presence or absence of deformation to evaluate shape retention.
(Foaming ratio)
The specific gravity (ρf) of the foam sheet was measured by an underwater substitution method and calculated as a ratio ρs / ρf with respect to the specific gravity (ρs) of the resin before foaming.
(Average bubble diameter)
It calculated | required according to ASTMD3576-77. That is, an SEM photograph of a sheet cross section was taken, a straight line was drawn on the SEM photograph in the horizontal direction and the vertical direction, and the length t of the bubble chord crossed by the straight line was averaged. Assuming that the magnification of the photograph is M, the average bubble diameter d was determined by substituting it into the following equation.
d = t / (0.616 × M)
(Total reflectance)
The total reflectance at a wavelength of 550 nm was measured using a spectrophotometer (U-4100: manufactured by Hitachi High-Tech). In Table 1, the total reflectance of a white plate made of hardened aluminum oxide fine powder is defined as 100%, and the total reflectance of each thermoplastic resin foam is shown as a relative value.
(Flame retardance)
UL94HB (horizontal combustion test) was evaluated according to the UL94 standard. The flammability determination criteria are in the order of (HF1)>(HF2)>HBF> fail.
(Elongation)
For mechanical properties, a sheet having a thickness of 1.0 mm was used, a sample of length × width × thickness = 100 mm × 5 mm × 1.0 mm was cut out, and a tensile elongation test was performed at a distance between chucks of 20 mm and a tensile speed of 50 mm / min. .

Example 1
100 parts by mass of polyethylene terephthalate (grade: RP560, manufactured by Toyobo), 3.8 parts by mass of ethylenebispentabromobenzene (grade: FCP-801, manufactured by Suzuhiro Chemical), 1.3 parts by mass of antimony trioxide, functional After adding 1 part by mass of SEBS having a base (Dynalon 8630P, manufactured by JSR) and kneading, it was molded into a sheet of 0.6 mm thickness × 430 mm width × 180 m length. This resin sheet is overlapped with an olefin-based nonwoven fabric separator (grade: FTC-50, manufactured by Nippon Vilene) with a thickness of 280 μm × 420 mm width × 180 m length and a basis weight of 50 g / m ² , and the surfaces of the resin sheets are in contact with each other. It was rolled into a roll shape so that there was no part to do.

  Thereafter, the roll was placed in a pressure vessel, pressurized to 5 MPa with carbon dioxide gas, and carbon dioxide gas was permeated into the resin sheet. The carbon dioxide gas permeation time into the resin sheet was 48 hours.

  Next, the roll was taken out from the pressure vessel, and while removing the separator, the resin sheet alone was continuously supplied to a hot-air circulating foaming furnace set at around 220 ° C. so that the foaming time was 1 minute, and foamed.

  The obtained foam was uniformly foamed, and the average cell diameter was as very fine as 10 μm. The total reflectance of the foam sheet was as high as 99.8%. Moreover, the flame retardance of the obtained foam was as good as HBF, and the elongation was as high as 117%. The shape retention was good.

(Example 2)
The same as Example 1 except that the addition amount of ethylenebispentabromobenzene was 7.5 parts by mass and the addition amount of antimony trioxide was 2.5 parts by mass with respect to 100 parts by mass of polyethylene terephthalate (same as above). .

  The obtained foam was uniformly foamed, and the average cell diameter was as fine as 15 μm. The total reflectance of the foam sheet was as high as 99.6%. Moreover, the flame retardance of the obtained foam was as good as HF-1, and the elongation was as high as 84%. The shape retention was good.

(Example 3)
The same as Example 1 except that the addition amount of ethylenebispentabromobenzene was 11.3 parts by mass and the addition amount of antimony trioxide was 3.8 parts by mass with respect to 100 parts by mass of polyethylene terephthalate (same as above). .

  Although the obtained foam had slightly non-uniform bubbles, the average bubble diameter was as fine as 18 μm. The total reflectance of the foam sheet was 99.0%. Moreover, although the flame retardance of the obtained foam was as favorable as HF-1, elongation showed the low value as 56%. The shape retention was good.

(Comparative Example 1)
Except for adding 7 parts by mass of ethylenebispentabromobenzene to 100 parts by mass of polyethylene terephthalate (same as above) and adding 3 parts by mass of modified PE (Mitsubishi Chemical) as the thermoplastic resin (D). Same as 1.

  The obtained foam had slightly non-uniform bubbles, and the average bubble diameter was 20 μm. The total reflectance of the foam sheet was 98.0%. Moreover, although the flame retardance of the obtained foam was as favorable as HF-1, elongation showed the low value as 40%. The shape retention was good.

(Comparative Example 2)
Example 1 was the same as Example 1 except that ethylene bispentabromoben and a flame retardant aid were not added to polyethylene terephthalate (same as above).

  The obtained foam was very uniformly foamed, and the average cell diameter was very fine as 3 μm. The total reflectance of the foam sheet was as high as 100.3%. However, the flame retardancy was bad and bad. The elongation was as high as 150%. The shape retention was good.

(Comparative Example 3)
The same as Example 1 except that the addition amount of ethylene bispentabromobenzene with respect to 100 parts by mass of polyethylene terephthalate (same as above) was 1.5 parts by mass and the addition amount of antimony trioxide was 0.5 parts by mass. .

  The obtained foam was uniformly foamed, and the average cell diameter was very fine at 5 μm. The total reflectance of the foam sheet was as high as 100.2%. However, the flame retardancy was unacceptable. The elongation was as high as 140%. The shape retention was good.

The results are shown in Table 1. Judgment is that the bubble diameter is 20 μm or less, the specific gravity is 0.7 or less, the reflectance is 99% or more, the elongation is 56 % or more, the flame retardancy is HBF or more, and the shape retainability is all good. But what did not satisfy was made into x.

It is sectional drawing which shows the light reflection board produced in the Example of this invention.

Explanation of symbols

1 Polycarbonate foam

Claims (5)

As a thermoplastic resin (A), 100 parts by mass of polyethylene terephthalate,
2-10 parts by mass of a non-decabromo flame retardant (B),
Flame retardant aid (C) 0.8-4 parts by mass;
From a thermoplastic resin to which 0.1 to 10 parts by mass of a styrene-ethylene-butadiene-styrene block copolymer is added as a thermoplastic resin (D) having a functional group having an affinity for the thermoplastic resin (A) A sheet of
A thermoplastic resin foam having a plurality of pores therein and an average cell diameter of 20 μm or less.   2. The thermoplastic resin foam according to claim 1, wherein the specific gravity is 0.7 or less. The thermoplastic resin foam according to claim 1 or 2 , wherein the non-decabromo flame retardant (B) is ethylene bispentabromobenzene. The thermoplastic resin foam according to any one of claims 1 to 3, wherein the flame retardant aid (C) is antimony trioxide. Contains a thermoplastic resin (A), a non-decabromo flame retardant (B), a flame retardant aid (C), and a thermoplastic resin (D) having a functional group having an affinity for the thermoplastic resin (A) Holding the resin sheet in a pressurized inert gas atmosphere to contain the inert gas in the resin sheet, and heating and foaming the resin sheet containing the inert gas under normal pressure The thermoplastic resin foam according to any one of claims 1 to 4 , wherein the thermoplastic resin foam is produced by a production method.

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