JPH07278386A - Low-smoking, low-toxic and flame retardant vinyl chloride compound - Google Patents

Abstract

PURPOSE:To obtain a low-smoking, low toxic and flame retardant vinyl chloride compound suitable as a coating material for electric wires capable of especially minimizing the smoking in combustion without containing a conventional halogen-based flame retardant and antimony trioxide and further suppressing the generation of toxic gases such as carbon monoxide. CONSTITUTION:This low-smoking, low toxic and flame retardant vinyl chloride compound contains 2-10 pts.wt. zinc stannate or 3-15 pts.wt. zinc hydroxystannate as a flame retardant in a flame retardant vinyl chloride compound comprising 100 pts.wt. vinyl chloride resin, 40-60 pts.wt. plasticizer, 3-10 pts.wt. stabilizer and 20-100 pts.wt. flame retardant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low smoke and low toxicity vinyl chloride resin compound mainly used as a material for coating electric wires.

[0002]

2. Description of the Related Art Vinyl chloride (PVC) resin is used in large quantities as a wire coating material by making use of its characteristics such as electric insulation, weather resistance and flame retardancy. Furthermore, the demand for flame retardancy has become stronger due to the serious fire accidents that have occurred in the past, and various flame retardant P
Although VC cables have been developed and put to practical use, these cables generate a large amount of smoke when a fire occurs, and this has hindered evacuation and fire extinguishing activities in enclosed spaces such as underground malls, subways, and ships. Since there is a possibility of causing a disaster, it is desired to develop a low-smoke emitting material that produces less smoke during a fire. In addition, reduction of harmful gases such as carbon monoxide generated during combustion is also strongly desired as another subject of flame retardancy.

Generally, in the combustion of polymer materials, oxygen reacts with the gas decomposed by heat to burn, and if the combustion heat is sufficient at that time, the heat causes a new combustible substance to undergo the next thermal decomposition. Continue the wake cycle. That is, in order to continue burning the material, (1) presence of combustible material, (2) supply of oxygen,
(3) Three elements of maintaining temperature (heat energy) are necessary. Preventing even one of these three factors leads to interruption of combustion. Specific examples of the method for preventing the reaction include addition of a substance that stops the radical reaction (a halogen-based additive, etc.) and addition of a substance that blocks the supply of oxygen (for example, a halogen-based flame retardant represented by a bromine-based flame retardant). , Nitrogen-based flame retardants, phosphorus-based flame retardants, etc.) and addition of substances that cause heat absorption to lower the temperature (addition of aluminum hydroxide, magnesium hydroxide, zinc borate, etc.) Have been going. In particular, halogen-based flame retardants are widely used in combination with antimony trioxide as conventionally used flame retardants. However, in the case of the polymers to which these flame retardants are added, there is a drawback that the amount of smoke generated increases, and various metal compounds such as zinc borate have been proposed instead of antimony trioxide.

[0004]

However, until now, sufficient results have not been obtained regarding flame retardancy, particularly low smoke generation and low toxicity.

The present invention has been made to address the above-mentioned problems, and in particular, it suppresses smoke generation during combustion and carbon monoxide (carbon monoxide) without containing a conventional halogen-based flame retardant and antimony trioxide. An object of the present invention is to provide a flame-retardant PVC compound suitable as an electric wire coating material in which generation of toxic gas such as CO) is suppressed.

[0006]

The low smoke and low toxicity flame retardant PVC compound of the present invention comprises 100 parts by weight of vinyl chloride resin, 40 to 60 parts by weight of a plasticizer, 3 to 10 parts by weight of a stabilizer, and a flame retardant agent. 20-100 other fillers as a combustor
It is a soft PVC compound consisting of 1 part by weight, characterized in that it contains 3 to 15 parts by weight of zinc hydroxystannate and / or 2 to 10 parts by weight of zinc stannate as the flame retardant.

The zinc hydroxystannate has the chemical formula ZnSn.
It is a white powder having a particle size represented by (OH) ₆ of 1 to 10 μm and a decomposition starting temperature of about 180 ° C.

On the other hand, zinc stannate is a white powder having a particle size represented by the chemical formula ZnSnO ₃ of 1 to 10 μm and a decomposition temperature exceeding 570 ° C.

The above-mentioned zinc hydroxystannate and / or zinc stannate can significantly reduce the amount and rate of smoke and CO generated from the resin, as compared with the conventionally used antimony trioxide. Do you get it. The mechanism is that zinc contained in the structural formula promotes the formation of a carbonized layer as a catalyst for the dehydrohalogenation reaction of the resin and suppresses the generation of smoke, and the endothermic reaction due to the volatilization of water accompanying thermal decomposition burns. Lower the temperature. Furthermore, the vapor phase flame retardant effect of partial volatilization of zinc (Zn) and tin (Sn) at 550 ° C. or higher brings about the effect of reducing CO, and the vapor phase produced by the condensed layer for forming a carbonized layer and the volatile flame retardant gas. It is considered that the flame-retardant effect in Example 1 is synergistic to obtain an excellent effect.

As described above, ZnSn (OH) ₆ has a decomposition initiation temperature of about 180 ° C. and undergoes primary thermal decomposition at 190 to 285 ° C. to release water to become ZnSnO ₃ . This ZnSnO ₃ decomposes at a temperature of 580 ° C. or higher to produce Zn ₂
SnO ₄ and SnO ₂ . Therefore, ZnSn (O
H) ₆ is mainly on the low temperature side of the pyrolysis temperature range, and ZnS
nO ₃ is effective on the high temperature side.

The above zinc hydroxystannate and / or zinc stannate are more preferably used in combination with other conventionally known inorganic flame retardants such as metal hydroxides. That is, by using a combination of aluminum hydroxide, a metal hydroxide typified by magnesium hydroxide, and / or zinc borate, it is possible to significantly reduce the amount of smoke and improve the oxygen index. .
The metal hydroxide dissociates water during combustion and absorbs heat to lower the temperature. Further, zinc borate serves to form a carbonized layer by promoting dehydrochlorination in vinyl chloride resin as well as absorbing heat by releasing crystal water during combustion. By combining these flame retardants or auxiliaries with zinc hydroxystannate and / or zinc stannate, it is possible to obtain a soft vinyl chloride compound which is slow in ignition at the time of combustion, has little smoke, and is nontoxic.

The amount of the metal hydroxide added is in the range of 10 to 50 parts by weight with respect to 10 parts by weight of the resin. Further, zinc hydroxystannate and / or zinc borate added at the same time as zinc stannate are in the range of 0 to 15 parts by weight with respect to 10 parts by weight of the resin.

In the flame-retardant PVC compound of the present invention, the amount of zinc hydroxystannate is limited to 3 to 15 parts by weight. When the amount is less than 3 parts by weight, sufficient flame retardancy cannot be obtained, and 15 parts by weight is used. If it exceeds the above range, the dynamic thermal stability required for producing the compound and for coating the electric wire cannot be obtained, and the general physical properties after the processing are deteriorated. It is preferably in the range of 5 to 10 parts by weight. On the other hand, the amount of zinc stannate is limited to the range of 2 to 10 parts by weight is 2
If it is less than 10 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 10 parts by weight, the dynamic thermal stability required for producing a compound or for coating an electric wire cannot be obtained. The general physical properties are inferior. Therefore, the range of 3 to 8 parts by weight is preferable.

The vinyl chloride resin used in the present invention has a polymerization degree Mw of about 1300, but not only a straight polymer but also a copolymer such as vinyl acetate can be used.

Although a general-purpose DOP is used as a plasticizer, since this soft vinyl chloride resin contains a large amount of an inorganic flame retardant, it is subjected to shearing when used for compound processing, wire coating, etc. Since it is easy to generate heat and work is sometimes forced to be performed at high temperatures, it is desirable to endure processing at the highest temperature possible.
Plasticizers such as DINP and DIDP having more excellent heat resistance are more preferable.

Further, the production of a PVC compound using zinc hydroxystannate and / or zinc stannate and the wire coating process are conventional flame-retardant PV containing aluminum hydroxide.
It is carried out in the same way as the production of C compound.

[0017]

[Function] An inorganic flame retardant containing zinc hydroxystannate and / or zinc stannate is used in place of the conventional halogen flame retardant-antimony trioxide to delay the ignition time during combustion of PVC compound. Can be
In addition, it has become possible to achieve low smoke generation and low toxicity.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Examples 1 to 6) As test materials, 50 parts by weight of a general-purpose plasticizer DOP in accordance with a general-purpose electric wire coating material and 100 parts by weight of a general-purpose lead-based stabilizer are used with respect to 100 parts by weight of PVC having a polymerization degree of 1300. The composition of the flame retardant system is such that zinc borate is 20 parts by weight and the total amount of aluminum hydroxide and zinc hydroxystannate or zinc stannate is 50 parts by weight. Selected. Table 1
The above flame-retardant PVC compounding composition is shown.

[0020]

[Table 1] These compositions were mixed in a blender, then kneaded by a two-roll mill, and press-molded to obtain a test sample.

The evaluation of the test sample includes flame retardancy, smoke generation,
Corrosion and thermal stability were performed.

The flame retardancy was evaluated based on JIS K7201 (oxygen index method), and the oxygen index OI was measured.

The smoke emission property is determined by measuring the optical smoke concentration according to ASTM E662-83 (a method for measuring smoke concentration of combustion gas).
E1354-90 (Cone Calorimeter method) was used to measure the heat generation rate and heat generation amount of the material from the oxygen consumption amount during the combustion of the material, and the ignition time, smoke concentration, generated gas, etc. were measured.

The corrosiveness was evaluated by quantifying the amount of HCl gas generated during PVC combustion in accordance with JCS C53.

Regarding the thermal stability, JIS K6723
Dehydrate the sample by immersing the sample in an oil tank kept at 180 ° C
The static thermal stability test to measure the time of 1 and the dynamic thermal stability test to measure the time when the sample starts thermal decomposition and the kneading torque rises at 100 revolutions using a Labo Plastomill at a mixer temperature of 180 ° C. went.

Comparative Examples 1 to 3 As Comparative Example 1, as in Examples 1 to 6, 15 parts by weight of a bromine-based flame retardant and 10 parts by weight of antimony trioxide were added to the base composition, and oxygen was added. A sample having an index of 33 was used. Further, as Comparative Example 2, 35 parts by weight of aluminum hydroxide was used as a flame retardant, and as Comparative Example 3, a sample having a compounding composition in which 50 parts by weight of aluminum hydroxide and 20 parts by weight of zinc borate were added was used. The test was conducted in the same manner as.

[0027]

[Table 2] The test results are shown in Table 2.

First, regarding the oxygen index, Examples 1 to 6 were used.
Shows values exceeding 35, which means that the oxygen index 33 of Comparative Example 1 of the conventional flame-retardant PVC compound containing a halogen-based flame retardant and antimony trioxide as a flame retardant can be sufficiently substituted. . Further, as shown in Comparative Example 2, when aluminum hydroxide alone is blended as a flame retardant, the oxygen index is significantly lowered, and aluminum hydroxide alone cannot provide sufficient flame retardancy. Further, when aluminum hydroxide and zinc borate are used in place of the halogen-based flame retardant and antimony trioxide as in Comparative Example 3, a value equivalent to an oxygen index of 33.8 is shown.
There is a clear difference compared to ~ 6. As described above, by replacing a part of the flame retardant system of aluminum hydroxide + zinc borate with zinc hydroxystannate or zinc stannate as described in Examples 1 to 6, the flame retardancy represented by the oxygen index can be obtained. It has become clear that further improvements will be made.

Next, regarding the concentration of smoke generated during combustion, in the case of Comparative Example 1 containing only an organic halogenated flame retardant, a large amount of halogen gas was generated during combustion and further reacted with antimony to halogenate. Since it forms antimony and shuts off oxygen in the gas phase, the amount of smoke generated is larger than that of a general-purpose PVC compound. Further, in the case of Comparative Example 2 containing aluminum hydroxide alone as a flame retardant, although an endothermic effect by the crystal water of aluminum hydroxide was expected, no effect was observed on the amount of smoke generated. In the case of this example, it was confirmed that the same amount of smoke generation as in Comparative Example 3 in which 50 parts of zinc borate was added to the PVC resin exhibited the same amount of smoke emission.

Regarding the ignition time at the time of combustion, in comparison with the conventional flame-retardant PVC compound Comparative Example 1 in which a halogen-based flame retardant and antimony trioxide were added as flame retardants, Comparative Example 2 using aluminum hydroxide alone was used. By comparison, both were able to be significantly delayed.

Regarding the amount of generated HCl gas, in Examples 4, 5 and 6 containing 7 parts or more of zinc stannate, a considerable reduction was observed as compared with the composition of Comparative Example 3.

Next, regarding the peak calorific value and the total calorific value at the time of combustion determined from the combustion characteristics by a cone calorimeter, the aluminum hydroxide of Comparative Example 3 containing 50 parts of aluminum hydroxide and 20 parts of zinc borate as a flame retardant was used. Example 1 substituted with zinc hydroxystannate or zinc stannate
It was found that the compound of -6 reduced both the peak calorific value and the total calorific value.

(Examples 7 to 13) As in Examples 1 to 6, a system consisting of 100 parts of PVC resin, 50 parts of plasticizer DOP and 8 parts of stabilizer was added to 40 parts of aluminum hydroxide as a flame retardant. And zinc borate and zinc stannate in the amounts shown in Table 3. As a comparative example, zinc stannate-free zinc borate alone is added, and as a flame retardant system, it is composed of 15 parts of a conventional organic halogen-based flame retardant (HFR), 10 parts of antimony trioxide, and 40 parts of aluminum hydroxide. A compound was also prepared for comparison of workability.

[0034]

[Table 3] For the compositions shown in Table 3, a rapid rise of torque due to thermal decomposition was measured under the conditions of a temperature of 180 ° C. and a rotation speed of 100 rpm by using a Labo Plastomill mixing device to obtain dynamic thermal stability. A test sample was prepared in the same manner as in Example 1,
Tensile strength, 100% modulus and elongation were measured as mechanical strength. Further, a heat aging test was carried out at 100 ° C. for 120 hours to measure the strength after aging. Moreover, the amount of smoke generation and the amount of heat generation were measured similarly to the samples 1-6.

Table 4 shows the measurement results.

[0036]

[Table 4] From Table 4, it is possible to confirm a sufficient decrease in the amount of smoke generation and the decrease in the amount of heat generation even in the present experiment in which 40 parts of aluminum hydroxide, 15 parts of zinc borate and 15 parts of zinc stannate were used. Examples 14 to 15 As in Example 1, 8 parts by weight of a lead-based stabilizer was used per 100 parts by weight of PVC resin, and D was used as a plasticizer instead of DOP.
50 parts by weight of INP was used, magnesium hydroxide was used as the flame retardant instead of aluminum hydroxide, and zinc borate and zinc stannate were used as the flame retardant aids of the present invention. In addition, the amount of the inorganic filler containing a flame retardant other than the stabilizer was reduced to 35 parts, and the test was conducted on a compound usable as a general-purpose electric wire cable sheath. As comparative examples, a flame retardant magnesium hydroxide alone to the plasticizer DOP, a flame retardant magnesium hydroxide alone to the plasticizer DINP, and a flame retardant magnesium hydroxide and a flame retardant auxiliary to the plasticizer DINP. As a result, a combination of only zinc borate was prepared. The above composition is shown in Table 5.

[0037]

[Table 5] The above composition was molded in the same manner as in Example 1 and subjected to the test.

Tensile test and oxygen index of the sample were measured, and further the tensile test after heat aging at 100 ° C. × 120 hr and the volatilization loss were measured. The results are shown in Table 6.

[Table 6] From the above results, it was confirmed that Examples 14 and 15 have the same mechanical strength as Comparative Examples 8 and 9 which have been conventionally used. In addition, the heat aging property also has a plasticizer DINP.
It is improved by adopting. Moreover, regarding the flame retardancy in question, a remarkable improvement in the oxygen index was observed. That is, zinc stannate was used in place of a part of magnesium hydroxide as compared with the use of mere magnesium hydroxide as a flame retardant (Comparative Example 9) or the use of magnesium hydroxide and zinc borate (Comparative Example 10). In both Example 15 and Example 14 in which zinc stannate and zinc borate were used in place of a part of magnesium hydroxide, the oxygen index was clearly improved.

[0039]

As a novel flame retardant, the halogen type flame retardant and the antimony trioxide type flame retardant which have been used conventionally are replaced by
By containing zinc stannate or zinc hydroxystannate as a flame retardant, the ignition time is delayed and the smoke generation is low.
It has become possible to achieve low toxicity.

[0040]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasushi Kato 1-4-4 Shintoda, Hamamatsu City, Shizuoka Prefecture Incorporated Electric Cable Technical Center

Claims (7)

[Claims] 1. A vinyl chloride resin 100 parts by weight, a plasticizer 40 to 60 parts by weight, a stabilizer 3 to 10 parts by weight, and a flame retardant 20.
To 100 parts by weight of a flame-retardant soft vinyl chloride compound, wherein the flame retardant contains 2 to 10 parts by weight of zinc stannate. A low-smoke / low-toxicity flame-retardant vinyl chloride compound. 2. A vinyl chloride resin 100 parts by weight, a plasticizer 40 to 60 parts by weight, a stabilizer 3 to 10 parts by weight, and a flame retardant 20.
To 100 parts by weight of a flame-retardant soft vinyl chloride compound, the flame retardant comprises zinc hydroxystannate in an amount of 3 to
Low smoke and low toxicity flame retardant vinyl chloride compound characterized by containing 15 parts by weight. 3. The vinyl chloride compound according to claim 1 or 2, wherein the flame retardant further comprises a metal hydroxide.
Low smoke and low toxicity flame retardant vinyl chloride compound characterized by containing 50 to 50 parts by weight. 4. The vinyl chloride compound according to claim 3, wherein the metal hydroxide is aluminum hydroxide, which is a low smoke and low toxicity flame retardant vinyl chloride compound. 5. The low-smoke / low-toxicity flame-retardant vinyl chloride compound according to claim 3, wherein the metal hydroxide is magnesium hydroxide. 6. The low smoke / low toxicity flame retardant vinyl chloride compound according to claim 1, wherein the flame retardant further contains 0 to 15 parts by weight of zinc borate. . 7. The vinyl chloride compound according to claim 1, wherein the vinyl chloride compound has a tensile strength of 1.5 kgf / mm ² or more, an elongation of 200% or more, and an oxygen index of at least 32 or more. A low-smoke, low-toxic flame-retardant vinyl chloride compound.