JPH0778171B2 - Flame-retardant thermoplastic composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to thermoplastic compositions.
In particular, the present invention relates to a thermoplastic composition containing a silicone-based additive that imparts unexpectedly improved flame retardant properties to the thermoplastic composition.

[0002]

Aluminum trihydrate (aluminum hydroxide, ATH) is widely used in the plastics industry as a flame retardant filler for thermoplastic resins and elastomeric compositions. ATH for thermoplastics and elastomers
Although filled, the copolymers are economical, but lack good fire resistance and good physical properties.

Various efforts have been made in the past to increase the flame retardancy of thermoplastic compositions containing aluminum trihydrate. See, for example, US Pat. No. 4,387,176 to Frye, US Pat. No. 4,496,680 to Ashby, and US Pat. No. 4,536,529 to Frye et al. I want to.

Frye US Pat. No. 4,387,1
No. 76 discloses a flame-retardant thermoplastic composition comprising a thermoplastic polymer, a silicone fluid or gum, a Group IIA metal organic salt, a silicone resin and, optionally, aluminum trihydrate. It is disclosed. This flame-retardant composition is most effective when a halogen is added.

The discovery that formed the basis of this Frye invention was that "some metal soaps (eg magnesium stearate) were added in the correct proportions to some silicone resins (eg polytriorganosilylsilyl). It is possible to obtain an efficient flame-retardant plastic by combining it with a mixture of a cation) and a polydiorganosiloxane polymer. [Frye, column 2, column 4]
~ Line 8]. The invention of Frye's patent
"In some respects, and in particular in that the use of a combination of polyorganosiloxane silicone and silicone resin achieves a synergistic flame retardant effect not taught in the prior art. It's different. "
Is stated.

Ashby US Pat. No. 4,49
No. 6,680, diphenylsilanediol, low molecular weight phenyl-substituted siloxanediols or mixtures thereof, Group IIA metal carboxylates, aluminum trihydrate, and organic halides. As an optional ingredient,
A nylon composition which becomes substantially flame retardant when combined with an additive composition comprising a silicone resin as disclosed in Frye's U.S. Pat. No. 4,387,176 is disclosed. It is disclosed.

Frye et al., US Pat. No. 4,536,36
No. 529 discloses a flame retardant composition containing a thermoplastic polymer, a silicone fluid, a metal soap precursor, a silicone resin, and, optionally, alumina trihydrate.

The invention of Frye et al. Discloses certain metal soap precursors (eg, stearic acid, a precursor of magnesium stearate, and a reactive magnesium compound),
Efficient flame retardant thermoplastics can be made by mixing certain silicone fluids and silicone resins in the correct proportions during compounding and adding this mixture to the thermoplastic. [Frye et al., Column 1, lines 46-55]. This fly (F
The additives of rye) et al. reduce mechanical properties less than conventional flame retardants and improve impact resistance, gloss and processability.

Another patent, Lovgren
Et al., U.S. Pat. No. 4,487,858, claims a propylene / polydimethylsiloxane / MQ resin blend containing aluminum trihydrate, talc and a cross-linking agent, at column 6 thereof. , Lines 35-41, the blend is further described as "Group IIA metal organic compounds or salts (magnesium stearate, calcium stearate, barium stearate, which enhance the flame retardancy of the thermoplastic / silicone fluid blends. Etc.) ”may be included.

All of the above-discussed patents indicate that the presence of Group IIA metal organic salts in addition to the silicone fluid and silicone resin is required to improve the flame retardancy of the thermoplastic composition. I am teaching. The presence of the Group IIA metal organic salt enhances the melt flow properties of the thermoplastic composition. However, for certain applications, such as sheet extrusion, it is desirable to use a thermoplastic composition having lower melt flow properties.

[0011]

OBJECTS OF THE INVENTION Accordingly, one object of the present invention is to
A with improved flame retardancy and reduced melt flow
It is to provide a thermoplastic composition filled with TH.

Another object of the invention is improved flame retardancy,
An object is to provide an ATH filled thermoplastic composition having reduced melt flow and good or acceptable physical properties.

These objects are achieved by the present invention.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a Group IIA metal carboxylic acid by adding to a thermoplastic resin a specific amount of silicone fluid and silicone resin taught in the above-mentioned patents. It is based on the discovery that the flame retardancy and certain physical properties of thermoplastic compositions can be improved without the use of salts.

In one aspect, the present invention provides a thermoplastic composition consisting essentially of the following components with improved flame retardant properties. A. About 30 to about 60 parts by weight of a thermoplastic resin, B. About 40 to about 70 parts by weight of aluminum trihydrate [provided that the total of (A) and (B) is 100 parts], C.I. Silicone oil, and D.I. Silicone resin soluble in silicone of component C [provided that the ratio of (C) to (D) is about 2: 1 to about 2.5: 1, and that of (C) and (D) The total is 1 of (A) + (B)
About 4 to about 12 parts per 00 parts].

In another aspect, the present invention relates to a method of improving the flame retardancy of a thermoplastic composition consisting essentially of components A and B of the above composition, which method comprises essentially the following:
It comprises the step of adding components C and D to the thermoplastic composition in the above amounts.

The invention further relates to an article consisting of a substrate coated with the thermoplastic composition of the invention.

In addition to improved flame retardancy, the compositions of the present invention also have improved low temperature impact strength and anti-dripping properties and reduced melt flow.

The composition of the present invention is used in the construction industry, the construction industry,
And useful in the wire insulation and cable insulation industries.

[0020]

DETAILED DESCRIPTION OF THE INVENTION As already mentioned, the discovery on which the present invention is based is that the addition of a predetermined amount of silicone oil and silicone resin to a thermoplastic composition filled with ATH results in a Group IIA compound. This means that the flame retardancy of the thermoplastic composition can be improved without the use of metal carboxylates.

The present invention has improved flame retardancy and is essentially (A) a thermoplastic polymer, (B) aluminum trihydrate, and a specified amount of (C) silicone oil. And (D) a thermoplastic resin composition comprising a silicone resin.

Thermoplastic polymers suitable as component (A) of the composition of the present invention include, for example, polyethylene [eg low density polyethylene (LDPE), high density polyethylene (HDPE)], polypropylene, polybutylene, and the like, and these copolymers - polyolefins, such as, polystyrene, Lexan (Lexan ^R) polycarbonate, such as brand - Bonnet - door and Varox (V
alox ^R) thermoplastic polyester such as resin [Both General Electric Company (General Electric Co
mpany)], and polyamide [for example, Nylon 66, Nylon 12, etc.], polycaprolactam, ionomer, polyurethane, acrylonitrile-butadiene-styrene copolymers and terpolymers, acrylic polymers. , Acetal resins, ethylene-vinyl acetate, polymethylpentene, flexible polyvinyl chloride, polyphenylene oxide, polyphenylene oxide-polystyrene blends or copolymers [eg General Electric Company
Noryl ^R polymer made by lectric Company)],
There are other polymers such as Monsanto's Santoprene and Uniroyal TPR thermoplastic polyesters. Thermoplastic polymers suitable for use in the present invention are referred to herein as "thermoplastic resins".
Sometimes referred to collectively. One skilled in the art will be able to adapt and optimize the flame retardant composition of the present invention for a wide variety of thermoplastic formulations including engineering plastics. The above list is not exhaustive and the invention is not limited thereto.

The composition of the present invention contains a thermoplastic polymer, ie, component (A), in an amount of about 30 to about 60 parts by weight, preferably about 30 to about 40 parts by weight, most preferably about 40 parts by weight.

Component (B) of the composition of the present invention is aluminum trihydrate, which imparts flame retardancy to the thermoplastic composition by dehydration when exposed to the heat of the combustion process. To do.

Generally, the aluminum trihydrate will range from about 40 to about 70 parts by weight, preferably from about 60 to about 70.
It can be present in the compositions of this invention in the range of parts by weight, most preferably in an amount of about 60 parts by weight.

The total of components (A) and (B) in the composition of the present invention is 100 parts.

Component (C) of the composition of the present invention is silicone oil. The term "silicone oil" as used herein is a general term for a wide range of polysiloxane materials that can be advantageously utilized in the compositions of the present invention. For the purpose of describing the present invention in detail, the expression "silicone oil" is referred to as "MacLaur"
It is to be understood to include the effective silicone materials described in US Pat. No. 4,273,691 to y) et al., which are hereby incorporated by reference. In general, effective silicone materials are silicone fluids or gums such as: That is, typically R ₃ SiO
_0.5 , R ₂ SiO, R ¹ SiO _1.5 , R ¹ R ₂ SiO
_0.5 , RR ¹ SiO, (R ¹ ) ₂ SiO, RSi
It is an organopolysiloxane with chemically bonded siloxy units selected from the group consisting of O _1.5 and SiO ₂ units and combinations thereof. However, each R independently represents a saturated or unsaturated monovalent hydrocarbon group, and R ¹ is a group such as R, or a hydrogen atom, a hydroxyl group, an alkoxy group, an aryl group, It represents a group selected from the group consisting of a vinyl group, an allyl group and the like. Further, the organopolysiloxane is 2
It has a viscosity of about 600-300,000,000 centipoise at 5 ° C. The preferred silicone material is 25 ° C
Is a polydimethylsiloxane having a viscosity of about 90,000 to 150,000 centipoise. Such effective silicone materials are collectively referred to as silicones or silicone oils and should be distinguished from the group of materials known as silicone resins. Such silicone oils are readily available in various brands and grades.

Component (D) is a silicone resin, which is the silicone oil (ie, fluid or gum).
It is soluble in water and is effective in imparting improved flame retardancy to the composition of the present invention. Among the preferred silicone resins is the MQ silicone resin. The expression "MQ silicone resin" means that typical of such resins are composed mainly of monofunctional M units of the formula R ₃ SiO _0.5 and tetrafunctional Q units of the average formula SiO _2. , Specific M
Refers to the fact that it has a / Q unit ratio. A particularly effective silicone resin for use in the present invention is a polytrimethylsilyl silicate that can have a ratio of about 0.3 to 4.0 M units per 1 Q unit. A particularly effective formulation is preferably about 0.02 per Q unit.
It may have a ratio of 6 to 2 M units. An example of a commercially available MQ silicone resin is General Electric SR545 (M in toluene).
Q resin solid content 60%). A preferred method of utilizing such MQ resin solution is to mix it with the silicone oil component and then remove the solvent. This solvent can be removed by known methods, for example by distillation at moderate temperatures.

Components (C) and (D) comprise about 2: 1 to about 2.
It is present in the composition of the invention in a ratio of 5: 1, preferably about 2.3: 1. The sum of components (C) and (D) in the composition of the present invention is about 4 to about 12 parts, preferably about 5 to about 10 parts, most preferably about 100 parts of (A) + (B). It ranges from about 5 to about 7 parts.

It is particularly important that components (C) and (D) are present in the composition of the present invention within the above proportions and amounts. If the proportion and amount of the above-mentioned parameters deviate, flame retardancy and other properties are inferior.

Other silicone oil soluble forms of the solid silicone resin are also believed to be effective for use in the flame retardant compositions of the present invention. In fact, MT and TQ silicone resins (where T is trifunctional RSiO
_1.5 units), and mixtures and copolymers with the above resins would also be effective. These silicone resins are well known materials and are easily available. The criterion for suitability is whether such effective silicone resinous materials are soluble or dispersible in silicone oil bases.

Further, the above thermoplastic composition defines the (nearly D-functional) silicone oil and the (M, D, T or Q functional) silicone resin as separate components to be mixed. However, it should be noted that the present invention also includes reaction products of such materials which may be similarly effective as flame retardant additives. Also, instead of the separate silicone oil component and silicone resin component, the required M,
It is also envisioned that copolymers containing D, T or Q functionality may be used.

The composition of the present invention may further contain various fillers such as talc, clay, calcium carbonate, fumed silica, wollastonite and the like. Other suitable fillers will be apparent to those skilled in the art.

In practicing the present invention, the flame retardant composition is prepared using any of the conventional melt compounding equipment such as a Banbury mixer, a twin screw extruder, or a two roll rubber mill. It can be made by mixing a thermoplastic polymer with silicone oil and silicone resin. The twin-screw extruder is expected to be the most reproducible for obtaining the product. An example of a suitable blending technique is Lovgren et al., US Pat. No. 4,4.
87,858, which is incorporated herein by reference.

The order of addition of the individual components does not appear to have any particular significance. However, one of ordinary skill in the art can optimize the flame retardant composition of the present invention without undue experimentation. Silicone resin and silicone polymer are
Prior to compounding with the thermoplastic / ATH composition in the extruder, it is preferable to premix to form a homogeneous mixture.

The thermoplastic resin and aluminum trihydrate are also typically pre-blended prior to adding the silicone blend thereto. The thermoplastic resin / ATH composition, silicone resin and silicone oil are typically compounded at temperatures in the range of about 100-200 ° C. The preferred compounding temperature is in the range of about 120-160 ° C.

The flame-retardant composition according to the invention can be extruded onto a conductor and, in special cases, crosslinked depending on the presence or absence of a peroxide curing agent. Of course, there are many other applications where the flame retardant composition of the present invention can be used to great advantage. The composition of the present invention can be easily processed into an end product such as an extrusion coating of a wire or a cable, and a sheet-like extruded product as various construction materials.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order that those skilled in the art may better understand the embodiments of the present invention, the following examples are given by way of illustration and not limitation.

[0039]Practical experiment  In the following examples and tables and the accompanying figures, "SFR1
"00" means a silano having a viscosity of about 120,000.
54 parts by weight of polydimethylsiloxane terminated at the end
And MQ resin dissolved in toluene or xylene 60% solution
It means a blend containing 46 parts by weight of liquid. "LDP
"E" is for Union Carbide Compa
manufactured under the trademark "DPDA-1682" by
Made of ethylene-ethyl acrylate copolymer
Means low density polyethylene, and "phr" is 100
It means the part per copy.

As will be appreciated by those skilled in the art, there are several ways to test and compare the relative flame retardancy of thermoplastics. Among the best known are the limiting oxygen index and horizontal and vertical burn tests.

US Insurer Institute Standards (Underwriters' L
abaratories Bulletin) UL-94, "Burning Test for Classifying
Materials) "is described (hereinafter," UL-94 ").
Called). According to this test procedure, the material is divided into Y-0, VI and V-II based on the test results of 5 test pieces. The test results are evaluated according to the following criteria. V-0: A flame that does not exceed 5 seconds in average combustion and / or glow time after excluding the flame for ignition, and any test piece ignites absorbent cotton or burns it for more than 10 seconds. No particles are dropped. VI: Average flame and / or glow time after extinguishing the flame for ignition must not exceed 25 seconds and any test piece will ignite absorbent cotton or burn longer than 30 seconds. No particles are dropped. VI: Average burning and / or glow time after extinguishing the flame for ignition must not exceed 25 seconds (no test piece should burn longer than 30 seconds) and ignite absorbent cotton Flame particles drip from the test piece.

The vertical flammability tests performed on the following examples generally follow the test procedure described in UL-94.

Example 1 is for making a composition within the scope of the present invention.
The structure is illustrated.Example 1  Thermoplastics [eg ethylene-acrylic acid
-Based low density polyethylene (ie LDP
E), Union Carbide Compan
manufactured under the trade name "DPDA-6182" by y)
Has been added] and LD with a mixture of aluminum trihydrate
Manufactured with PE: ATH = 40: 60, Banbury (B
anbury) compounding machine. Mix for 5 minutes at 160 ° C
Heated to melt. Next, 40:60 LDPE: A
5 phr silicone fluid to 100 parts of TH composition
Was introduced and the resulting mixture was blended for 5 minutes. All cyclists
After 10 minutes, take out the material and cut it into small pieces.
ASTM test specimen for injection molding of small pellets by polishing
AndExamples 2-9  Using the general procedure described in Example 1,
Eight samples having the composition shown were produced. Stearin
SF with and without MgO
R100 is a base resin (ie, low density polyethylene
40 parts len (LDPE) and 6 parts aluminum trihydrate
Determine the effect on various characteristics including flammability (part 0)
Decided The concentration of SFR100 used was in the range of 5-15%.
It was a fence. SFR100 and magnesium stearate
The ratio with (when used) is the previously mentioned Frye
As in U.S. Pat. No. 4,387,176 of 2:
I kept it at 1.

[0044]

[Table 1]Table 1  Example LDPE ATH SRF100 Magnesium stearateNumber % % phr phr  2 100 − −− − 3 40 60 −− − 4 40 60 5 − 5 40 60 5 5 2.5 6 40 60 10 10 − 7 40 60 10 10 5.0 8 40 60 60 15 −9 40 60 15 7.5  Table 2 shows the physical properties of the blends prepared in Examples 2-9.
I will give you. In Table 2, "MFI" is the melt flow index.
, "LOI" is the limiting oxygen index, "UL94"
Means each of the tests already described.

[0045]

[Table 2]Table 2  MFI at break Tensile Izod Example (c) LOI UL94 Tensile strength coefficient Elongation Bending rate -20 ℃ -50 ℃Number g / 10 minutes % Second Psi psi % psi ft.lb/in 2 12.32 ---- 1600 4260 29 5707 5.27 0.88 3 1.72 24.5 --2080 20500 71 101998 7.81 3.52 4 0.31 28.5 23.2 1625 18060 46 43330 8.94 7.61 5 4.48 28.7 30.3 633 17720 56 40720 10.43 8.8 6 0.3 28.0 14.3 1243 13855 39 81939 5.51 5 7 5.94 27.8 23.8 329 11173 65 98770 8.8 7.28 8 0.4 27.8 19.8 770 7874 36 181080 6.25 5.629 9.94 27.8 16.5 230 8060 40 32923 6.41 5 Examples 10-20  SFR100 and Silicone / Steary
Magnesium oxide is pure (ie contains no ATH)
Proof of effect of propylene on melt flow characteristics
In order to do so, 11 compositions having the compositions shown in Table 3 were
Manufactured.

[0046]

[Table 3]Table 3  ImplementationComposition (%) Example of melt index Stearic acid (a)number polypropylene SFR100 magnesium (G / min)  10 100.0 −−−− 7.0 11 97.5 2.5 −− 11.1.83 12 96.25 2.5 1.25 10.62 13 95.0 5.0 −− 12.0 14 92 .5 5.0 2.5 13.14 15 92.5 7.5 --- 14.0 16 88.75 7.5 3.75 16.21 17 90.0 10.0 --- 14.75 18 85 0.0 10.0 5.0 21.6 19 80.0 20.0 --20.3620 70.0 30.0 --- 52.5  (a) Melt index = flow rate at 230 ° C, 44 psi (load of 2.164 kgs) using a capillary die with the following dimensions: Die inner diameter = 0.0825 "Die length = 0.315" Tables 1 and 2 above And as can be seen from FIGS.
"40 LDPE / 60 ATH" resin (herein,
Also called "LDPE / ATH resin" / SFR100
The physical properties of lend show some unique trends.
You This will be described below.

The flammability of this blend is unique. AT
The H-LDPE resin itself has poor flame retardancy as shown in FIGS. 2, 3 and 4. Aluminum trihydrate 6
Addition of 0% does not improve the flame retardancy of polyethylene. However, the addition of SFR100 or silicon / magnesium stearate at various concentrations improves the limiting oxygen index and the extinguishing time (UL94 test). The oxygen index appears to be independent of the addition of magnesium stearate (Fig. 2), but the fire-extinguishing time appears to decrease at lower magnesium stearate concentrations (ie less than 5%,
(Figure 3).

That is, Tables 1 and 2 and FIGS.
In general, the data presented in section IIA
Group metal salts are not necessary to impart improved flame retardancy to high filler filler copolymers of polyethylene containing aluminum trihydrate and a critical amount of SFR100. is there.

Table 2 and FIGS. 5 to 8 show that SFR100 and silicon / magnesium stearate are LDPE / AT.
It shows the effect of H resin on various physical properties. The low temperature impact strength is outstanding for the sample containing SFR100 alone. Tensile elongation and tensile modulus do not appear to be affected by the further addition of magnesium stearate (Figures 7 and 8).

Overall, the evidence provided in the above table and figures suggests that in the case of a thermoplastic composition filled with ATH, a certain amount of SFR100 was present alone, ie without magnesium stearate. Then,
It is that many of the properties studied for flame retardancy of the thermoplastic composition are improved.

Modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that changes may be made in the above specific embodiments of the invention which fall within the fully intended scope of the invention as defined in the appended claims.

[Brief description of drawings]

FIG. 1 Combination of silicone oil and silicone resin (ie, “Silicone” and silicone)
3 is a graph showing the effect of silicone / magnesium stearate on the melt flow index of 40 parts ethylene-ethyl acrylate / 60 parts aluminum trihydrate copolymer (“40EEA / 60ATH”).

[Figure 2] Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
7 is a graph showing the effect of TH on the limiting oxygen index.

[Figure 3] Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
It is a graph which shows the effect which TH has on flammability.

[Fig. 4] Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
6 is a graph showing the effect of TH on impact strength at −20 ° C.

[Fig. 5] Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
6 is a graph showing the effect of TH on impact strength at −50 ° C.

[Fig. 6] Silicone (Silicone) and Silicone (Silicone)
one) / Magnesium stearate is 40EEA / 60A
7 is a graph showing the effect of TH on the tensile strength.

Fig. 7 Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
It is a graph which shows the effect which it has on the tensile coefficient of TH.

Fig. 8 Silicone and Silicon
one) / Magnesium stearate is 40EEA / 60A
7 is a graph showing the effect of TH on the tensile elongation.

Claims (16)

[Claims] 1. A. About 30 to about 60 parts by weight of a thermoplastic resin, B. About 40 to about 70 parts by weight of aluminum trihydrate [provided that the total of (A) and (B) is 100 parts by weight], C.I. Silicone oil, and D.I. Silicone resin soluble in silicone of component C [provided that the ratio of (C) to (D) is about 2: 1 to about 2.5: 1, and that of (C) and (D) The total is 1 of (A) + (B)
From about 4 to about 12 parts by weight per 00 parts by weight]. 2. The sum of the components (C) and (D) is (A) +
The composition of claim 1 which is from about 5 to about 10 parts per 100 parts of (B). 3. The sum of the components (C) and (D) is (A) +
3. About 5 to about 7 parts per 100 parts of (B).
The composition as described. 4. The ratio of component (C) to component (D) is about 2.
The composition of claim 1 which is 3: 1. 5. The silicone resin has an average formula R ₃ Si.
Monofunctional M unit of O _0.5 and tetrafunctionality Q of average formula SiO ₂
It is composed of units, and each Q unit averages about 0.3-
An MQ silicone resin having 4.0 M units,
The composition of claim 1. 6. The thermoplastic resin is polypropylene,
The composition of claim 1 selected from the group consisting of polyethylene, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene terpolymer, polyphenylene oxide-polystyrene blends, acrylic polymers, polyurethanes and polyamides. 7. Silicone oil is R₃SiO_0.5,
R₂SiO, RSiO_1.5, R¹R₂SiO_0.5, RR
¹SiO, (R¹)₂SiO, R¹SiO_{1. Five},and
SiO₂Of units and groups of combinations of these
An organopo in which siloxy units selected from
Lisiloxane, provided that each R is independent
Represents a saturated or unsaturated monovalent hydrocarbon group, R¹Is
Independently saturated or unsaturated monovalent hydrocarbons
Group, or hydrogen atom, hydroxyl group, alkoxy group,
Of the group consisting of aryl, vinyl or allyl groups
Represents a group selected from the group consisting of:
Is about 600 to 300,000,000 cm at 25 ° C
The composition of claim 1 having a poise viscosity. 8. Silicone oil at 90 ° C. at 25 ° C.
The composition of claim 7 which is an essentially linear polydimethylsiloxane copolymer having a viscosity of from 0 to 150,000 centipoise. 9. The composition of claim 1 wherein the thermoplastic resin is present in an amount of about 30 to about 40 parts by weight. 10. The composition of claim 9 wherein the thermoplastic resin is present in an amount of about 40 parts by weight. 11. The aluminum trihydrate is about 60 to about 7.
The composition of claim 1 present in an amount of 0 parts by weight. 12. The composition of claim 11, wherein the aluminum trihydrate is present in an amount of about 60 parts by weight. 13. A. About 40 parts by weight of a thermoplastic resin, B. About 60 parts by weight of aluminum trihydrate, C.I. Silicone oil, and D.I. Silicone resin soluble in silicone of component C [where the ratio of (C) to (D) is about 2.3: 1, (C)
And (D) is from about 5 to about 7 parts by weight per 100 parts by weight of (A) + (B)], a thermoplastic composition having improved flame retardant properties. 14. A method of improving flame retardancy of a thermoplastic composition comprising (A) about 30 to about 60 wt% thermoplastic resin and (B) about 40 to about 70 wt% aluminum trihydrate. And the thermoplastic composition is (C) a silicone oil, and (D) a silicone resin soluble in the component C, wherein the ratio of (C) to (D) is about 2 1 to about 2.5: 1 and the sum of (C) and (D) is about 4 to about 12 parts by weight per 100 parts by weight of (A) + (B)] from the step of mixing with How to be. 15. A product comprising a substrate coated with the flame retardant composition of claim 1. 16. The article of claim 15 wherein the substrate is a conductor.