JP2012126771A - Flame-retardant polyvinyl chloride raw material composition, and vinyl chloride molded article molded from the composition and having excellent flame retardancy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant polyvinyl chloride raw material composition capable of exhibiting high flame retardancy while coming into harmony with an environment without using the conventional halogen-based flame retardant, and exhibiting having high fluidity and excellent workability, and to provide a flame-retardant fired product molded from the composition.SOLUTION: The composition is prepared by incorporating a binary flame retardant as a flame retardant comprising a first flame retardant made of carbon and a second flame retardant made of phosphorus into a vinyl chloride raw material. The first flame retardant comprises a high conductive carbon black and expanded graphite; and the second flame retardant comprises red phosphorus and an organic phosphorus compound.

Description

  The present invention provides a flame retardant polymer that can exhibit high flame retardancy while harmonizing with the environment without using a conventional halogen flame retardant, and can exhibit excellent workability with good fluidity. The present invention relates to a raw material composition of vinyl chloride and a fired product having excellent flame retardancy.

  Vinyl chloride resin is not only inexpensive, but also has well-balanced physical properties such as processability, chemical resistance, weather resistance, scratch resistance, and electrical characteristics. In addition, it is widely used in various fields such as for architectural use, upholstery, and automobile parts (see, for example, Patent Document 1 and Patent Document 2). With the diversification of the purpose of use, vinyl chloride resin products are required to have a high level of flame retardancy, and the required performance, safety, and consideration for the environment are becoming stricter. It was. In addition, there are cases where the standard value is obligated by laws and regulations.

  Originally, the vinyl chloride resin itself is self-extinguishing with 56% chlorine, but the vinyl chloride paste contains a large amount of combustible plasticizer and has an average chlorine content of 30%. It is said that it will lose its self-extinguishing properties if it becomes below. For this reason, when a general vinyl chloride resin is exposed to a flame, it melts and thermally decomposes due to heat, generates a combustible gas, ignites and drip the resin while continuing combustion. become.

  Therefore, it has been proposed to improve the flame retardancy by adding a flame retardant. For example, there are magnesium hydroxide and aluminum hydroxide as flame retardants, but these have a problem that the amount of heat absorbed at the time of decomposition is small, so a large amount of addition is required, resulting in a decrease in mechanical strength, and also against weight reduction. It was. In the case of halogen-based flame retardants, high flame retardancy can be obtained by blending in a relatively small amount, but there is a lot of soot and smoke generation, which causes corrosion of processing machines and adverse effects on the human body. There was a problem of concern. Accordingly, development of a flame retardant polyvinyl chloride raw material composition using a new flame retardant has been desired.

JP-A-9-302593 JP-A-9-241460

  The combustion mechanism of vinyl chloride resin is as follows. First, when the surface of the molded body is heated by radiant heat emitted from a fire source, it is considered that the polymer melts due to heat conduction inside and undergoes thermal decomposition through low molecular weight. Most of the thermal decomposition of a polymer occurs by radical cleavage, and the higher the binding energy, the more difficult the thermal decomposition of the polymer. Vinyl polymers generally have a small C—C bond energy, and random decomposition and depolymerization easily occur. For this reason, combustible gas is generated by decomposition, the generated gas diffuses inside the molded body, and further, when the combustible gas reaches the surface of the molded body, it diffuses into the gas phase and ignites and burns. Will continue.

Therefore, the inventor of the present invention investigates what kind of material is effective in exhibiting a high degree of flame retardancy with a small amount of flame retardant composition, having no drip phenomenon during combustion, low smoke generation The combustion mechanism was analyzed.
The most noticeable part of the combustion cycle is the melt decomposition of polymers. Thermal decomposition occurs through a chain of radical reactions. That is, in the combustion phenomenon, the combustible gas generated by the thermal decomposition of the polymer becomes the subsequent combustion. This means that the reaction can be suppressed if the object uses a compound that traps radicals, and further, if the amount of combustible gas generated can be suppressed, a high degree of flame retardancy can be exhibited.

  From this, the first condition for exhibiting flame retardancy is that the ignition temperature is high, the thermal stability is excellent, the volatilization loss is small, and itself does not ignite. The second condition is the generation of a carbonized layer (char) by dehydration carbonization and radical trapping. The third condition is that the plasticizer is composed of a heat-resistant plasticizer (trimellitic acid mixed alkyl ester, dipentaerythritol, pyromellitic acid) and a flame-retardant plasticizer (cresylphenyl phosphate, resorcinol diphosphate, aromatic condensation). (Phosphate ester) is used together. The fourth condition is that when the viscosity is increased by the addition of the flame retardant, the fluidity in the mold is deteriorated and a molded product having the dimensions cannot be obtained, so that the addition amount is small. The fifth condition is that the environment is not hindered and there is no problem in health and safety. The sixth condition is to be compatible with the vinyl chloride paste raw material so as to ensure the fluidity of the raw material in molding.

The inventor of the present application satisfies the above first to sixth conditions, selects various materials as a low flame retardant advanced flame retardant having no drip phenomenon at the time of combustion, and repeated a lot of experiments on the blending amount. As a result, as a material that satisfies all the conditions, it is preferable to use a flame retardant composed of a binary system of a first flame retardant composed of fine particle carbon and a second flame retardant composed of phosphorus. I found.
More specifically, the first flame retardant made of carbon is preferably made of a combination of highly conductive carbon black and expanded graphite, and the second flame retardant made of phosphorus is made of red phosphorus and phosphorus. What consists of combined use with an acid ester is preferable. Furthermore, if the phosphoric acid ester is a mixture of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate, it not only exhibits an effect as an advanced flame retardant, but also as a plasticizer for polyvinyl chloride paste raw material. This is also preferable because it can exhibit the above-mentioned action.

  In addition, a composite flame retardant composed of the above-mentioned binary system of carbon and phosphorus (phosphate ester also acts as a plasticizer for the polyvinyl chloride paste raw material) is added to the polyvinyl chloride raw material. As a result of conducting a flame retardant test of the obtained molded product, it was confirmed that high flame retardancy (effect equivalent to V0 of “UL94”) without drip phenomenon during combustion can be secured. In addition, it was confirmed that the smoke generation was greatly reduced for the low smoke generation effect.

  The present invention is based on the facts found by the above-mentioned inventors, and without using a conventional halogen flame retardant or antimony trioxide flame retardant aid, a composite flame retardant comprising an environmentally friendly binary system. The present invention has been completed for the purpose of providing the flame-retardant polyvinyl chloride raw material used and a molded article excellent in flame retardancy formed thereby.

  This invention made in order to solve the said subject contains the flame retardant which consists of a binary system of the 1st flame retardant which consists of carbon as a flame retardant in the polyvinyl chloride raw material, and the 2nd flame retardant which consists of phosphorus. It is a flame retardant polyvinyl chloride raw material composition characterized by having been made.

  The first flame retardant made of carbon is preferably made of highly conductive carbon black and expanded graphite, and this is the invention according to claim 2.

  The second flame retardant made of phosphorus is preferably made of red phosphorus and an organic phosphorus compound, and this is the invention according to claim 3.

  The organic phosphorus compound is preferably a mixture of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate, which is an invention according to claim 4.

  Highly conductive carbon black: 0.1 to 2.0 parts by mass, expanded graphite: 2.0 to 10.0 parts by mass, red phosphorus: 0.5 to 10.0 parts by mass with respect to 100 parts by mass of the polyvinyl chloride raw material What is contained in the ratio of a part is preferable, and let this be the invention which concerns on Claim 5.

  Moreover, with respect to 100 mass parts of polyvinyl chloride raw materials, it is contained in the ratio of trimellitic acid mixed alkyl ester: 30.0-70.0 mass parts, cresyl phenyl phosphate: 10.0-40.0 mass parts. This is preferable, and this is the invention according to claim 6.

  Furthermore, the flame retardant polyvinyl chloride raw material composition described above is injected into a mold and molded by heating and firing. Invention.

  In the invention according to claim 1, a composite flame comprising a binary system of a first flame retardant comprising nano (nm) fine particle size carbon as a flame retardant and a second flame retardant comprising red phosphorus and phosphate ester. By containing a flame retardant, excellent flame retardancy can be exhibited with a small amount of flame retardant added, and it can be halogen-free and harmonized with the environment.

  In the invention according to claim 2, since the first flame retardant composed of carbon having a nano (nm) fine particle size is composed of highly conductive carbon black and expanded graphite, It is possible to suppress the expansion of combustion on the surface, prevent the melt from dripping and reduce the amount of smoke generated during combustion.

  In the invention which concerns on Claim 3, since the 2nd flame retardant which consists of phosphorus shall consist of red phosphorus and an organic phosphorus compound, the flame retardance excellent by the synergistic effect with the said carbon can be exhibited.

  In the invention according to claim 4, since the organic phosphorus compound is a mixture of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate, it not only acts as a flame retardant, but also as a plasticizer for the polyvinyl chloride paste raw material. Therefore, it is possible to have both functions of plasticization and flame retardancy (shortening of flame length and afterflame time) by ensuring fluidity without impeding plasticization efficiency.

  In the invention according to claim 5, since the content of the flame retardant is within a predetermined range, the amount of the flame retardant added can be reduced, the compatibility with the polyvinyl chloride raw material and the fluidity are good, and the molding is efficient. It can be performed.

  In the invention according to claim 6, since the contents of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate are within a predetermined range, the functions of plasticization and flame retardancy can be sufficiently exhibited.

  In the invention according to claim 7, at the time of combustion, a drip phenomenon does not occur, the after-flame time, the flame length is shortened, and the flame retardancy is low smoke generation, and the product according to the mold is efficiently used. Can be molded well.

It is a graph which shows the relationship between the amount of plasticizers and viscosity in the polyvinyl chloride raw material composition of this invention. It is a graph which shows the relationship between the organic phosphorus compound addition amount and the viscosity in the polyvinyl chloride raw material composition of this invention. It is a graph which shows the relationship between the organic phosphorus compound addition amount and after flame time in the polyvinyl chloride raw material composition of this invention. It is a graph which shows the relationship between the organic phosphorus compound addition amount and flame length in the polyvinyl chloride raw material composition of this invention.

Hereinafter, preferred embodiments of the present invention will be described.
The polyvinyl chloride raw material composition of the present invention is a binary system comprising a soft liquid (sol) polyvinyl chloride raw material as a first flame retardant comprising carbon as a flame retardant and a second flame retardant comprising phosphorus. And a composite flame retardant.
The first flame retardant made of carbon is a combination of high conductivity carbon black and carbon of the same group called expanded graphite, and the second flame retardant made of phosphorus is red phosphorus and organic phosphorus of an inorganic phosphorus compound. This is a combination of phosphorus compounds belonging to the same genera of the phosphate ester of the compound. When a composite flame retardant composed of such a binary system of carbon and phosphorus and composed of two types of the same group of materials is used for both carbon and phosphorus, all the above conditions 1 to 6 are satisfied. In addition to exhibiting a high degree of flame retardancy, it has been confirmed that it exhibits a great effect particularly in reducing flame and suppressing combustion.

Examples of the highly conductive carbon black include ketjen black, acetylene black, and oil furnace black. Ketjen black is particularly preferable. This ketjen black is nano (nm) level ultra fine particles with high conductivity and stable quality, and with the addition amount less than half compared with other highly conductive carbon black, the performance is equivalent or better. Obtainable.
The carbon element is an element having a melting point as high as 3550 ° C. In particular, the ketjen black and expanded graphite used in the present invention are ignited and combusted even if the flame by the Bunsen burner is directly contacted. It has been confirmed that it exhibits excellent heat resistance.

Red phosphorus and organic phosphorus compounds promote the formation of a carbonized film on the surface of the solid phase by dehydration carbonization. In addition, since the organic phosphate ester generates PO.radicals during combustion, the effect of capturing the generated radicals and suppressing the thermal decomposition of the polymer can be obtained.
In addition, organic phosphorous compounds mixed with trimellitic acid mixed alkyl ester and phosphoric acid ester are used, and these also act as a plasticizer for the polyvinyl chloride paste raw material, so that the plasticization efficiency is not hindered. It also functions as a combination of two functions: plasticization and flame resistance (reduction of flame length and afterflame time).
The above flame retardants of the present invention can be harmonized with the environment as halogen-free in place of conventional flame retardants of halogen compounds such as bromine chlorine, fluorine and iodine.

Highly conductive carbon black: 0.1 to 2.0 parts by mass, expanded graphite: 2.0 to 10.0 parts by mass, red phosphorus: 0.5 to 10.0 parts by mass with respect to 100 parts by mass of the polyvinyl chloride raw material It is preferably contained in a proportion of parts. When the content is less than the lower limit, the flame length is increased, the afterflame time is increased, and further, a drip phenomenon is also observed and the desired flame retardancy cannot be obtained. On the other hand, even if the content is higher than the upper limit, the flame retardant effect reaches a peak, and the upper limit is sufficient as the content.
The total content of the flame retardant is preferably in the range of 3.0 to 20 parts by mass. When the amount is less than the lower limit, sufficient flame retardancy cannot be obtained. On the other hand, when the amount is more than the upper limit, uniform mixing into the urethane raw material becomes difficult.

It is contained in a proportion of trimellitic acid mixed alkyl ester: 30.0 to 70.0 parts by mass and cresyl phenyl phosphate: 10.0 to 40.0 parts by mass with respect to 100 parts by mass of the polyvinyl chloride raw material. preferable. When the content is less than the lower limit, the action of the polyvinyl chloride paste raw material as a plasticizer cannot be sufficiently exhibited. On the other hand, if the content is higher than the upper limit, the fluidity of the vinyl chloride paste raw material is lowered, which is not preferable.
Moreover, it is preferable that these total content is the range of 50.0-80.0 mass parts with respect to 100 mass parts of polyvinyl chloride raw materials. If it is less than 50.0 parts by mass, the action as a plasticizer becomes insufficient, and if it exceeds 80.0 parts by mass, the mechanical strength is lowered, which is not preferable.

As described above, when a flame retardant comprising a binary system of a first flame retardant composed of highly conductive carbon black and expanded graphite and a second flame retardant composed of red phosphorus and an organic phosphorus compound is contained as a flame retardant. The reason for the flame retardant action is not clear, but is understood to be as follows.
In the oxidation reaction, oxygen reacts with oxygen, but if there is an inorganic substance with a very low enthalpy of the reaction, the substance itself becomes irrelevant to combustion, and the material per unit volume, that is, the polymer part. Decreases, the proportion of volatile combustible gas decreases, and the flame in the oxidation reaction field is suppressed. Furthermore, if the reaction between carbon and oxygen occurs, the oxygen concentration in the solid phase will decrease.
This action is mainly made of highly conductive carbon black (that is, nanoparticle-sized Ketjen black). In addition, for expanded graphite, as the temperature rises rapidly, the volume expands significantly to form a carbonized layer, and the carbonized shape exhibits a curled shape, which promotes the joint effect of the curled shape and strengthens the matrix. It works as a drip prevention during combustion.

In the present invention, a mixture of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate is used as the organic phosphorus compound. This organic phosphorus compound forms a carbonized layer on the surface of the organic material during combustion, and radicals such as HPO ₂ -PO generated by decomposition during combustion trap active H radicals and OH radicals in the gas phase. There exists an effect | action and there exists an effect which suppresses a combustion reaction. Furthermore, since these also act as plasticizers for the polyvinyl chloride paste raw material, the plasticity and flame retardancy (reduction of flame length and afterflame time) are ensured by preventing fluidization efficiency and ensuring fluidity. It functions as having both functions.
As described above, due to the synergistic effect of the composite flame retardant comprising the binary system of the first flame retardant comprising the highly conductive carbon black and the expanded graphite and the second flame retardant comprising the red phosphorus and the organic phosphorus compound, It is understood that it exhibits high flame retardancy and low smoke generation.

Examples of the present invention will be described below.
Table 1 shows materials used for the polyvinyl chloride raw material composition of the present invention. Table 2 shows the properties of the materials used, and Table 3 shows the ignition / flammability characteristics of the materials used by the Bunsen burner.

The materials shown in Table 1 were blended in the proportions shown in Table 4, and were uniformly mixed with a propeller stirrer at 1000-1500 rpm / min for 3 minutes. Next, this mixed solution is cast into a metal mold (150 W × 250 L × 10 H, unit: mm) for a predetermined thickness, and then heated and fired at 190 ° C. × 8 minutes in a gear oven to obtain a fired product (sheet). Obtained.
A test piece (10 W × 125 L × 1.6 t (thickness), unit: mm) was collected from the obtained fired product, and a combustion test according to “UL94 (20 mm vertical combustion test)” was performed.
"UL94" is an American flame test method that has become an international standard. The upper end of the burner tube is 10 ± 1 mm from the lower end of the test piece, and a flame is applied vertically to the center of the test piece. This is a method in which the distance is maintained for 10 ± 0.5 seconds, and the presence or absence of ignition of the absorbent cotton by the burning of the test piece and the molten fallen object is examined. The test conditions are as shown in Table 5 below.

  Table 4 shows the results of the obtained flame retardancy test. In the present invention, the ignition of the test piece was not recognized, and the phenomenon that the test piece melted and drip (dropped) on the absorbent cotton underneath was not observed. It was confirmed that there was a corresponding effect.

FIG. 1 shows the relationship between the addition amount (parts by mass) of an organic phosphorus compound (only trimellitic acid mixed alkyl ester) and the viscosity (MPa · s). From this graph, it can be seen that the viscosity decreases linearly as the amount of plasticizer added increases.
FIG. 2 shows the relationship between the addition amount of organic phosphorus compounds (in the case of only trimellitic acid mixed alkyl ester and in the case of mixing trimellitic acid mixed alkyl ester and cresyl phenyl phosphate) and the viscosity. From this graph, it can be seen that the plasticization efficiency is improved by the addition of cresylphenyl phosphate. This means that fluidity is improved and is an important factor for moldability.
FIG. 3 shows the relationship between the addition amount of the organic phosphorus compound and the after flame time. From this graph, it can be seen that the afterflame time can be shortened by the addition of cresylphenyl phosphate.
FIG. 4 shows the relationship between the amount of organic phosphorus compound added and the flame length. From this graph, it can be seen that the flame length can be shortened by the addition of cresylphenyl phosphate.

Next, the manufacture of automobile interior materials will be described as an example.
Polyvinyl chloride raw material compositions shown in the examples of Table 4 were prepared. This polyvinyl chloride raw material was poured into an aluminum mold coated with a release agent (URH-580 manufactured by Konishi Co., Ltd.). The mold is heated to a mold temperature of 45 ° C. in a hot air circulating heating furnace.
The mold after the injection was placed in a hot-air circulating heating furnace, and baked at 190 ° C. for 8 minutes. Thereafter, the molded product was taken out of the mold, and an automotive interior material having a predetermined shape made of polyvinyl chloride foam resin was obtained.
As a result of cutting out a test piece from this product and conducting a flame retardancy test by the combustion test method shown in Table 5, the test piece was not ignited. Moreover, the test piece melt | dissolved and the phenomenon of dripping (dropping) on the absorbent cotton set under was not seen, but it has confirmed that the outstanding flame retardance was exhibited.

Claims (7)

  A flame retardant polyvinyl chloride comprising a polyvinyl chloride raw material containing a binary flame retardant of a first flame retardant made of carbon and a second flame retardant made of phosphorus as a flame retardant. Raw material composition.   The flame retardant polyvinyl chloride raw material composition according to claim 1, wherein the first flame retardant comprising carbon is composed of highly conductive carbon black and expanded graphite.   The flame retardant polyvinyl chloride raw material composition according to claim 1, wherein the second flame retardant comprising phosphorus is composed of red phosphorus and an organic phosphorus compound.   The flame retardant polyvinyl chloride raw material composition according to claim 3, wherein the organic phosphorus compound is a mixture of trimellitic acid mixed alkyl ester and cresyl phenyl phosphate.   Highly conductive carbon black: 0.1 to 2.0 parts by mass, expanded graphite: 2.0 to 10.0 parts by mass, red phosphorus: 0.5 to 10.0 parts by mass with respect to 100 parts by mass of the polyvinyl chloride raw material The flame retardant polyvinyl chloride raw material composition according to claim 2 or 3 which is contained in a proportion of parts.   The trimellitic acid mixed alkyl ester: 30.0-70.0 parts by mass, cresyl phenyl phosphate: 10.0-40.0 parts by mass with respect to 100 parts by mass of the polyvinyl chloride raw material. 4. The flame retardant polyvinyl chloride raw material composition according to 4.   A flame retardant polyvinyl chloride raw material composition according to any one of claims 1 to 6, which is injected into a mold, heated and fired, and molded with excellent flame retardancy. .

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