JPH072861B2 - Flame-retardant resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant resin composition, and more particularly to a flame-retardant resin composition obtained by blending a chlorine-containing polymer with a flame retardant containing zinc borate.

[0002]

2. Description of the Related Art In order to prevent a great social confusion caused by a recent cable fire, it is required that an electric wire coating resin be provided with flame retardancy. The chlorine-containing polymer is one of various thermoplastic resins that is relatively incombustible, but it is not yet sufficiently satisfactory in that once the resin molded product catches a flame, it easily self-combusts. .

Conventionally, in order to impart flame retardancy to resins,
Various inorganic compounds or organic compounds have been blended as flame retardants. Among these flame retardants,
Zinc borate is known to leave a sticky combustion residue with electrical insulation after burning the compounded resin composition,
For example, in Japanese Examined Patent Publication No. 56-67363, zinc borate is used as a resin, and Al ₂ O ₃ , SiO ₂ , Sb ₂ O ₃ , and ZnO are used.
Alternatively, it has been described to blend with ZrO metal oxide, and it is also shown that this composition is useful as a coating for electric wires, cables and the like.

[0004]

However, it has been found that there are still problems to be solved in terms of heat resistance and flame retardancy when blending zinc borate with a chlorine-containing polymer such as vinyl chloride resin. That is, it is recognized that when a mixture of a polymer containing zinc borate and a chlorine-containing polymer is exposed to a high temperature, the resin composition rapidly changes its color to black and the mechanical properties of the resin are significantly deteriorated after a certain period of time. Such rapid discoloration to black and deterioration are the same as the phenomenon called zinc burning observed when a zinc-based heat stabilizer is used in vinyl chloride resin, and the heat resistance or heat stability of the chlorine-containing polymer is high. It is an important sexual issue.

Therefore, an object of the present invention is to provide a flame-retardant resin composition which is excellent in heat resistance and flame retardancy and does not cause discoloration or deterioration even when exposed to high temperatures.

[0006]

According to the present invention, the chlorine-containing polymer is coated with zinc borate particles having a surface area of 1 to 40 per entire surface.
There is provided a flame-retardant resin composition comprising a flame-retardant treated with an oxide of an alkaline earth metal, a hydroxide or a basic carbonate in a weight percentage.

[0007]

In the present invention, the alkaline earth metal oxide, hydroxide or basic carbonate present on the surface of the zinc borate particles remarkably improves the heat resistance of the basic polymer containing the zinc borate particles. It is based on the finding that it acts to improve For example, as shown in Table 1, vinyl chloride resin, zinc borate 10 PHR (parts by weight per 100 parts by weight of resin)
The composition obtained by blending with a stabilizer for vinyl chloride resin and discolored black when subjected to heat treatment at a temperature of 200 to 202 ° C. for 30 minutes, whereas zinc borate alone instead of zinc borate. A composition containing the same amount of particles treated with calcium hydroxide or magnesium hydroxide on the surface thereof does not discolor to black even when about twice or more time elapses upon heat treatment at the same temperature. It was confirmed.

The above-mentioned remarkable improvement in heat resistance of the flame-retardant resin composition of the present invention can be achieved only by using a flame-retardant agent having an alkaline earth metal hydroxide or the like on the surface of zinc borate particles. This is achieved, and it is not achieved at all by simply coexisting zinc borate and a hydroxide of an alkaline earth metal in the resin (see Table 3 described later). In the present invention, the presence of an alkaline earth metal hydroxide or the like on the surface of the zinc borate particles,
The reason why the heat resistance of the resin composition is remarkably improved is not yet fully clear, but it is considered as follows. That is,
The reason why zinc borate causes zinc burning (black discoloration and deterioration) of a chlorine-containing polymer is that zinc chloride is produced by the interaction of the two at high temperature, and this zinc chloride is a polyene produced by the dehydrochlorination reaction of the chlorine-containing polymer. This is probably because it has a catalytic effect on the formation of structures and carbonization. In the flame-retardant resin composition of the present invention, does the alkaline earth metal hydroxide or the like present on the surface of the zinc borate particles preferentially trap the generated hydrogen chloride to suppress the formation of zinc chloride? Or, even if zinc chloride is produced, it is considered to act to promote the decomposition thereof.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the zinc borate, all the zinc borate conventionally used as a flame retardant can be used. However, as a particularly excellent flame retardancy, the molecular formula 2ZnO.3B ₂ O ₃ .3. Examples thereof include zinc borate represented by 3 to 3.7H ₂ O. This zinc borate can have a wide range of particle diameters, but it significantly improves flame retardancy (oxygen index), improves mechanical properties such as elongation and impact strength, and improves surface smoothness of molded products. In order to further lower the embrittlement temperature and improve the cold resistance, the average particle size is 10
It is desirable to use those having a thickness of less than μm, particularly 0.5 to 6 μm. The zinc borate having such a minute particle size is obtained by subjecting the synthesized zinc borate to pulverization treatment by a jet mill, a ball mill, or the like, or by synthesizing zinc borate so that the primary particle size is as large as possible. It can be obtained by carrying out under the condition that aggregation between primary particles is suppressed as much as possible.

As the alkaline earth metal oxide, hydroxide or basic carbonate, quick lime, slaked lime, magnesium hydroxide, basic magnesium carbonate, barium hydroxide, etc. may be used alone or in combination of two or more kinds. obtain. The most effective compounds are magnesium hydroxide and calcium hydroxide in order of importance. It is desirable that the hydroxide or the like used has a particle size as fine as possible from the viewpoint of heat resistance. Generally, the particle size should be 10 μm or less.

In the flame retardant used in the present invention, the above-mentioned alkaline earth metal compound is contained in an amount of 1 to 40% by weight, particularly 5 to 30% by weight, based on the total amount (total amount of zinc borate and alkaline earth metal compound). It is also important, most preferably to use in an amount of 7 to 25% by weight. When the amount of the alkaline earth metal compound is less than the above range, even if the compound is present on the surface of the zinc borate particles,
The degree of improvement in heat resistance is extremely low. Further, when the amount of the alkaline earth metal compound is larger than the above range, the heat resistance is further improved but the flame retardancy (oxygen index) tends to be reduced as compared with the case where it is within the above range. According to the present invention, by setting the amount of the alkaline earth metal compound in the above range,
The heat resistance (blackening time) can be significantly increased while maintaining almost the same oxygen index as in the case of zinc borate alone.

[0012] To treat the surface of the zinc borate particles with the alkaline earth metal compound, any treatment means is employed, but preferably a substantially dry method and mixing under milling conditions are employed. . Mixing under milling conditions means mixing such that the alkaline earth metal compound is milled with zinc borate particles, and the fine particles of the alkaline earth metal compound produced by this milling sprinkle the zinc borate particles. means. It will be appreciated that in this milling mixture, the zinc borate particles are significantly harder than the alkaline earth metal compound and therefore the zinc borate particles act as a kind of grinding medium for the alkaline earth metal compound.

Examples of equipment used for milling and mixing include a Henschel mixer, super mixer, tube mill, ball mill, vibration mill, pin mill, grinder, atomizer and the like. The degree of milling and mixing can be known by measuring the bulk density of the mixture. That is, the bulk density of the mixture increases as the degree of milling and mixing increases and approaches a certain upper limit. Thus, by measuring the bulk density of the milling mixture, the end point of milling mixing can be known. It is recognized that this increase in bulk density is caused by the fine particles of the alkaline earth metal compound entering into the spaces between the zinc borate particles. In fact, when the relationship between the bulk density and the heat resistance of the ground mixture was examined, it was found that a mixture having a higher bulk density gave better results. The absolute value of the bulk density varies considerably depending on the particle size and particle shape of zinc borate, the type and blending of the alkaline earth metal compound, and cannot be unconditionally specified. It is easy to set the bulk density so that the degree of milling of the mixture will be a predetermined level in the combination of and a certain alkaline earth metal compound.

In the present invention, the above flame retardant is added to the chlorine-containing polymer in an amount of 1 to 40 PHR, particularly 5 to 30 P.
Used by blending in the amount of HR. The chlorine-containing polymer used in the present invention is not limited thereto, and examples thereof include polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polypropylene, chlorinated rubber, vinyl chloride-vinyl acetate copolymer, vinyl chloride- Ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride ternary copolymer Polymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate ternary copolymer Combined, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid Ter copolymers, vinyl chloride-methacrylic acid ester copolymers, vinyl chloride-acrylonitrile copolymers, polymers such as internally plasticized polyvinyl chloride, and these chlorine-containing polymers and polyethylene, polypropylene, polybutene, poly- Α-Olefin polymers such as 3-methylbutene or ethylene-vinyl acetate copolymers, polyolefins such as ethylene-propylene copolymers and copolymers thereof,
Polystyrene, acrylic resin, copolymer of styrene and other monomer (for example, maleic anhydride, butadiene, acrylonitrile, etc.), acrylonitrile-butadiene-styrene copolymer, acrylic ester-butadiene-styrene copolymer, methacryl Examples thereof include blended products of acid ester-butadiene-styrene copolymer.

In the flame-retardant resin composition of the present invention, the flame retardant may be blended in the chlorine-containing polymer alone with the other flame retardant, in addition to being blended in the chlorine-containing polymer alone. Other flame retardants that can be used in combination can include antimony, zircon, molybdenum, aluminum, oxides of silica, hydroxides and sulfides, etc. Often obtained.

The flame-retardant resin composition of the present invention contains various additives known per se, such as stabilizers, plasticizers, antioxidants, light stabilizers, nucleating agents, fillers, organic chelates and pigments. , Antistatic agent, basic inorganic acid salt, antifogging agent, plateout prevention agent, surface treatment agent, lubricant, fluorescent agent, antifungal agent, bactericide, photodegradation agent, processing aid, release agent, etc. can do.

These additives may be preliminarily blended in the chlorine-containing polymer, or may be simultaneously mixed at the time of kneading the chlorine-containing polymer and the flame retardant.

[0018]

【Example】

Preparation of zinc borate A solution containing 663 g of boric acid and 5980 g of water was prepared.
This solution was heated to 85 ° C., and zinc borate (2
10 g of ZnO.3B ₂ O ₃ .3.5H ₂ O) was added as a seed. Boric acid 19 with vigorous stirring of the heated solution
82 g and 936 g of zinc oxide were added to the heated solution over about 1 hour, and a stirring reaction was carried out for 5 hours while maintaining the temperature at 85 ° C. The reaction was then filtered and separated into crystals and filtrate. The crystalline substance is washed with about 5 liters of water and then at 120 ° C.
It was dried in a constant temperature dryer for 12 hours. The obtained zinc borate was 2300 g. The analysis result of this is Zn
_{O: 37.91%, B 2 O} 3: 47.70%, H 2 O:
It was 14.39%. The average particle size of the particle size distribution measured by the Coulter Counter method was 8 μm (zinc borate a). This zinc borate a was crushed by a jet mill to obtain a powder having an average particle size of 2 μm (zinc borate b). Example 1 45 g of the above zinc borate a and 5 g of commercially available calcium hydroxide
1 to 1.5 mmφ in a 1.5 liter porcelain pot mill
0.5 g of alumina balls was added and the mixture was ground and mixed for 4 hours to obtain about 43 g of flame retardant A. The flame retardant A obtained here is mixed with a polyvinyl chloride resin (PVC) together with other additives in a predetermined ratio to obtain a flame retardant resin composition A ₁ -A.
₃ was obtained (additives and compounding amounts are also shown in Tables 1 to 3).

The following tests were conducted on the flame-retardant resin compositions A _{1 to} A ₃ to evaluate heat resistance and flame retardancy. The results are shown in Tables 1 to 3. (Heat resistance test) A very thin silicone oil was applied to the surface of a hard glass plate, and a 0.7 mm-thick kneading sheet was cut into 40 mm x 30 mm so as to be in close contact with the hard glass plate. It was placed in a gear oven maintained at 0 ° C., taken out at each time, and heat resistance was evaluated by the coloring degree of the sheet surface. Heat resistance evaluation method ○ No discoloration to black color at all △ Partial discoloration to black color × Whole discoloration to black color (flame retardancy test) Toyo Seiki Co., Ltd. Using a candle manufacturing combustion tester, the method was carried out according to JIS-K-7201B method, and the limiting oxygen index (OI%) was obtained. The larger the oxygen index (%), the better the flame retardancy. Example 2 270 g of zinc borate b and commercially available magnesium hydroxide 30
g in a porcelain pot mill of 7 liters together with 2.5 liters of porcelain balls of 10 to 20 mmφ for 5 hours of milling and mixing, and then pulverized by an atomizer to obtain flame retardant B about 300
g was obtained.

This flame retardant B was added to PVC together with other additives in the same manner as in Example 1 to obtain flame retardant resin compositions B _{1 to} B ₃
Was obtained, and the same test as in Example 1 was performed. The results and blending ratios are shown in Tables 1 to 3. Example 3 320 g of zinc borate b and reagent primary calcium hydroxide 80
g was preliminarily mixed in a polyethylene bag, and then triturated and mixed three times with an atomizer having a 0.5 mmφ screen to obtain about 400 g of flame retardant C.

This flame retardant C was blended with PVC together with other additives in the same manner as in Example 1 to obtain flame retardant resin compositions C _{1 to} C ₃
Was obtained, and the same test as in Example 1 was performed. The results and blending ratios are shown in Tables 1 to 3. Example 4 360 g of zinc borate b and 40 g of commercially available magnesium hydroxide
Was put into a super mixer with an internal capacity of 5 liters manufactured by Kawada Mfg. Co., Ltd., and the mixture was ground and mixed for 3 minutes to obtain a flame retardant D. The flame retardant D was ground and mixed 1 to 4 times with an atomizer having a 0.5 mmφ screen. And the following flame retardants E to H about 400
g was obtained.

[0022]For each of the flame retardants D to H, other additives are added to PVC.
Flame retardant resin composition D₁ ~ D₃ , E
₁ ~ E₃ , F₁ ~ F₃ , G₁ ~ G₃ , H₁ ~ H ₃ Got
It was The test was conducted in the same manner as in Example 1. Results and formulation
The ratios are shown in Tables 1 to 3. Example 5 270 g of fine zinc borate b and commercially available basic magnesium carbonate
30 g of the mixture was placed in the same super mixer as in Example 4 and 3
Milling and mixing was performed for 0 minutes to obtain about 300 g of flame retardant I.

This flame retardant I was added to PVC together with other additives.
Flame retardant resin composition I formulated in the same manner as in Example 1₁ ~ I₃ 
Was obtained, and the same test as in Example 1 was performed. As a result and distribution
The combined ratios are shown in Tables 1 to 3. Comparative Example 1 Zinc borate a as a flame retardant was directly compounded in PVC
Flame-retardant resin composition J obtained in the case₁ ~ J₃ about
The results are shown in Tables 1 to 3 as in Example 1. Comparative Example 2 Zinc borate b as a flame retardant was directly compounded in PVC
Flame-retardant resin composition K obtained in some cases₁ ~ K₃ about
The results are shown in Tables 1 to 3 as in Example 1. Comparative Example 3 100 g of zinc borate b and reagent primary calcium hydroxide 10
0g was premixed in a polyethylene bag beforehand
Crush with an atomizer of 0.5mmφ screen 3 times
Mixing was performed to obtain about 200 g of flame retardant L. This flame retardant L
Was mixed with PVC in the same manner as in Example 1 together with other compounding agents,
Flame-retardant resin composition L₁ ~ L₃ Obtained and tested in the same manner as in Example 1.
Test was carried out. The results and blending ratios are shown in Tables 1 to 3.
You Comparative Example 4 Commercially available zinc borate (average particle size 13μ) 180 g and reagent first grade
Calcium hydroxide 20g made of polyethylene beforehand
After premixing in a bag, use a screen with a 0.5 mmφ screen.
Grind and mix three times with a mizer to add about 200 g of flame retardant M
Obtained. Example of this flame retardant M in PVC together with other compounding agents
Flame retardant resin composition M ₁ ~ M₃ Got
These were tested in the same manner as in Example 1. That conclusion
The fruits and blending ratios are shown in Tables 1 to 3. Comparative Example 5 Zinc borate a18PHR and commercially available calcium hydroxide 2PH
R and Sb₂ O₃ 10 PHR, Al (OH)₃ 20 PHR
(Parts by weight per 100 parts by weight of resin)
Kneading with a kneading roll kept at 0 ℃ for 8 minutes
We made a 0.7mm sheet and the heat resistance of this sheet
The results of the test and the measurement of oxygen index are shown in Table 3.

As can be seen from Tables 1 to 3, the flame retardant having a composition different from that of the flame retardant used in the present invention (Comparative Examples 1 and 2) and a compounding amount (Comparative Examples 3 and 4) were used. In Comparative Examples 1, 2 and 4, the resin composition is excellent in flame retardancy (oxygen index) but inferior in heat resistance, and Comparative Example 3 is excellent in heat resistance but inferior in flame retardancy. However, unlike the product of the present invention, it did not have both heat resistance and flame retardancy.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

EFFECTS OF THE INVENTION According to the present invention, a chlorine-containing polymer is blended with a flame retardant having a surface of zinc borate particles containing an alkaline earth metal hydroxide or the like to improve heat resistance and flame retardancy. It was possible to provide a resin composition which was excellent and did not discolor or deteriorate even when exposed to high temperatures.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C09K 21/14 (72) Inventor Hiroshi Sawada 11-52 Shinkaimachi, Tsuruoka City, Yamagata Prefecture

Claims (1)

[Claims] 1. A chlorine-containing polymer is blended with a flame retardant obtained by treating the surface of zinc borate particles with 1 to 40% by weight based on the total amount of an alkaline earth metal oxide, hydroxide or basic carbonate. A flame-retardant resin composition comprising: